Gene Summary

Gene:KPNA2; karyopherin subunit alpha 2
Aliases: QIP2, RCH1, IPOA1, SRP1alpha, SRP1-alpha
Summary:The import of proteins into the nucleus is a process that involves at least 2 steps. The first is an energy-independent docking of the protein to the nuclear envelope and the second is an energy-dependent translocation through the nuclear pore complex. Imported proteins require a nuclear localization sequence (NLS) which generally consists of a short region of basic amino acids or 2 such regions spaced about 10 amino acids apart. Proteins involved in the first step of nuclear import have been identified in different systems. These include the Xenopus protein importin and its yeast homolog, SRP1 (a suppressor of certain temperature-sensitive mutations of RNA polymerase I in Saccharomyces cerevisiae), which bind to the NLS. KPNA2 protein interacts with the NLSs of DNA helicase Q1 and SV40 T antigen and may be involved in the nuclear transport of proteins. KPNA2 also may play a role in V(D)J recombination. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2016]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:importin subunit alpha-1
Source:NCBIAccessed: 11 March, 2017


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Nuclear Proteins
  • Chromosome 17
  • Gene Knockdown Techniques
  • MicroRNAs
  • RNA Interference
  • Staging
  • Cell Proliferation
  • Breast Cancer
  • Up-Regulation
  • Neoplasm Grading
  • Tissue Array Analysis
  • Disease Progression
  • Western Blotting
  • Immunohistochemistry
  • Y-Box-Binding Protein 1
  • Neoplasm Proteins
  • Oligonucleotide Array Sequence Analysis
  • Messenger RNA
  • Disease-Free Survival
  • Proportional Hazards Models
  • Transcription Factors
  • Gene Expression Profiling
  • siRNA
  • Cancer Gene Expression Regulation
  • Gene Expression
  • Lung Cancer
  • Prostate Cancer
  • DNA-Binding Proteins
  • Cell Cycle Proteins
  • Sodium Selenite
  • beta-Transducin Repeat-Containing Proteins
  • Esophageal Cancer
  • Multivariate Analysis
  • Biomarkers, Tumor
  • Tumor Microenvironment
  • Cell Cycle
  • Mutation
  • Active Transport, Cell Nucleus
  • Base Sequence
  • Cell Movement
  • Cell Nucleus
Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: KPNA2 (cancer-related)

Hass HG, Vogel U, Scheurlen M, Jobst J
Gene-expression Analysis Identifies Specific Patterns of Dysregulated Molecular Pathways and Genetic Subgroups of Human Hepatocellular Carcinoma.
Anticancer Res. 2016; 36(10):5087-5095 [PubMed] Related Publications
BACKGROUND: Hepatocellular carcinoma comprises of a group of heterogeneous tumors of different etiologies. The multistep process of liver carcinogenesis involves various genetic and phenotypic alterations. The molecular pathways and driver mutations involved are still under investigation.
MATERIALS AND METHODS: DNA micorarray technology was used to identify differentially expressed genes between human hepatocarcinoma and non-tumorous liver tissues to establish a unique specific gene-expression profile independent of the underlying liver disease. The validity of this global gene-expression profile was tested for its robustness against biopsies from other liver entities (cirrhotic and non-cirrhotic liver) by diagnosing HCC in blinded samples.
RESULTS: Most of the consistently and strongly overexpressed genes were related to cell-cycle regulation and DNA replication [27 genes, e.g. cyclin B1, karyopherin alpha 2 (KPNA2), cyclin-dependent kinase 2 (CDC2)], G-protein depending signaling [e.g. Rac GTPase activating protein 1 (RACGAP1), Rab GTPase YPT1 homolog (RAB1), and ADP-ribosylation factor-like 2 (ARL2)] and extracellular matrix re-modelling or cytoskeleton structure [22 genes, e.g. serine proteinase inhibitor 1 kazal-type (SPINK1), osteopontin (OPN), secreted protein acidic and rich in cysteine (SPARC), collagen type 1 alpha2 (COL1A2), integrin alpha6 (ITGA6), and metalloproteinase 12 (MMP12)]. Furthermore, significantly differentially expressed genes (e.g. calcium-binding proteins, G-proteins, oncofetal proteins) in relation to tumor differentiation were detected using gene-expression analysis.
CONCLUSION: It is suggested that these significantly dysregulated genes are highly specific and potentially utilizable as prognostic markers and may lead to a better understanding of human hepatocarcinogenesis.

Stelma T, Chi A, van der Watt PJ, et al.
Targeting nuclear transporters in cancer: Diagnostic, prognostic and therapeutic potential.
IUBMB Life. 2016; 68(4):268-80 [PubMed] Related Publications
The Karyopherin superfamily is a major class of soluble transport receptors consisting of both import and export proteins. The trafficking of proteins involved in transcription, cell signalling and cell cycle regulation among other functions across the nuclear membrane is essential for normal cellular functioning. However, in cancer cells, the altered expression or localization of nuclear transporters as well as the disruption of endogenous nuclear transport inhibitors are some ways in which the Karyopherin proteins are dysregulated. The value of nuclear transporters in the diagnosis, prognosis and treatment of cancer is currently being elucidated with recent studies highlighting their potential as biomarkers and therapeutic targets.

Takada T, Tsutsumi S, Takahashi R, et al.
KPNA2 over-expression is a potential marker of prognosis and therapeutic sensitivity in colorectal cancer patients.
J Surg Oncol. 2016; 113(2):213-7 [PubMed] Related Publications
BACKGROUND: Karyopherin α 2 (KPNA2) is a member of the Karyopherin α family and has recently been reported to play an important role in tumor progression. The aim of the current study was to elucidate the clinicopathological significance of KPNA2 over-expression in colorectal cancer (CRC).
PATIENTS AND METHODS: KPNA2 expression was evaluated by immunohistochemistry in 122 surgically resected CRC and 13 biopsy specimens obtained at colonoscopy during screening for preoperative hyperthermochemoradiation therapy (HCRT). The association between KPNA2 expression and clinicopathological features and preoperative HCRT efficacy were examined.
RESULTS: The high and low KNPA2 expression groups were comprised of 91 (74.6%) and 31 CRC patients, respectively. A significant association was observed between high expression and lymphatic invasion (P = 0.0245). KPNA2 high expression group had decreased overall survival (P = 0.00374). Multivariate analysis demonstrated high KPNA2 expression was independently associated with poor prognosis. Histological examinations revealed 11 (84.6%) and 2 (15.4%) of cases were KPNA2 positive and negative, respectively. Pathological complete response (pCR) was observed in 9.1% of KPNA2-positive cases and 100% of KPNA2-negative cases.
CONCLUSION: High KPNA2 expression was found to be associated with poor prognosis and resistance to HCRT.

Zhang Y, Zhang M, Yu F, et al.
Karyopherin alpha 2 is a novel prognostic marker and a potential therapeutic target for colon cancer.
J Exp Clin Cancer Res. 2015; 34:145 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Karyopherin alpha 2 (KPNA2), a member of the karyopherin family, plays a vital role in carcinogenesis. Yet its role in colon cancer is poorly characterized. We sought to clarify the clinical significance of its dysregulated expression in human colon tumor specimens.
METHODS: We evaluated KPNA2 mRNA and protein expression by real-time polymerase chain reaction and Western blotting in 40 primary colon cancer tissues and paired adjacent normal colon mucosa specimens. KPNA2 protein expression in colon tissue microarray of tumor and normal tissue specimens and lymph node metastasis specimens obtained from 195 colon cancer patients were analyzed immunohistochemically. The effect of KPNA2 knockdown on carcinogenesis potential of human colon cancer cells was determined using Cell Counting Kit-8 (CCK8), colony formation, cell migration, and tumorigenesis in nude mice.
RESULTS: KPNA2 was expressed at higher levels in colon tumors and lymph node metastasis specimens than in normal tissues. Patients with KPNA2-positive tumors were significantly correlated with the American Joint Committee on Cancer (AJCC) stage (p = 0.01), T-classification (p = 0.018), regional lymph node metastasis (p = 0.025), distant metastasis (p = 0.014), and differentiated degree (p = 0.001). KPNA2 was shown to be an independent prognostic indicator of disease-free survival (HR 1.681; 95 % CI: 1.170-2.416; p = 0.005) and overall survival (HR 2.770; 95 % CI: 1.314-5.837; p = 0.007) for patients with colon cancer. Knockdown of KPNA2 expression inhibited colon cancer cell proliferation, colony formation, and migration.
CONCLUSION: KPNA2 might play an important role in colorectal carcinogenesis and functions as a novel prognostic indicator and a potential therapeutic target for colorectal cancer.

Lu Y, Xiao L, Liu Y, et al.
MIR517C inhibits autophagy and the epithelial-to-mesenchymal (-like) transition phenotype in human glioblastoma through KPNA2-dependent disruption of TP53 nuclear translocation.
Autophagy. 2015; 11(12):2213-32 [PubMed] Free Access to Full Article Related Publications
The epithelial-to-mesenchymal (-like) transition (EMT), a crucial embryonic development program, has been linked to the regulation of glioblastoma (GBM) progression and invasion. Here, we investigated the role of MIR517C/miR-517c, which belongs to the C19MC microRNA cluster identified in our preliminary studies, in the pathogenesis of GBM. We found that MIR517C was associated with improved prognosis in patients with GBM. Furthermore, following treatment with the autophagy inducer temozolomide (TMZ) and low glucose (LG), MIR517C degraded KPNA2 (karyopherin alpha 2 [RAG cohort 1, importin alpha 1]) and subsequently disturbed the nuclear translocation of TP53 in the GBM cell line U87 in vitro. Interestingly, this microRNA could inhibit autophagy and reduce cell migration and infiltration in U87 cells harboring wild-type (WT) TP53, but not in U251 cells harboring mutant (MU) TP53. Moreover, the expression of epithelial markers (i.e., CDH13/T-cadherin and CLDN1 [claudin 1]) increased, while the expression of mesenchymal markers (i.e., CDH2/N-cadherin, SNAI1/Snail, and VIM [vimentin]) decreased, indicating that the EMT status was blocked by MIR517C in U87 cells. Compared with MIR517C overexpression, MIR517C knockdown promoted infiltration of U87 cells to the surrounding structures in nude mice in vivo. The above phenotypic changes were also observed in TP53(+/+) and TP53(-/-) HCT116 colon cancer cells. In summary, our study provided support for a link between autophagy and EMT status in WT TP53 GBM cells and provided evidence for the signaling pathway (MIR517C-KPNA2-cytoplasmic TP53) involved in attenuating autophagy and eliminating the increased migration and invasion during the EMT.

Lin J, Zhang L, Huang H, et al.
MiR-26b/KPNA2 axis inhibits epithelial ovarian carcinoma proliferation and metastasis through downregulating OCT4.
Oncotarget. 2015; 6(27):23793-806 [PubMed] Free Access to Full Article Related Publications
Karyopherin alpha 2 (KPNA2) is a nuclear transport protein upregulated in many cancers. Our previous study has identified KPNA2 overexpression in epithelial ovarian carcinoma (EOC) tissues, which predicts poor prognosis. However, the mechanism of KPNA2 overexpression in EOC remains unclear. This study aimed to examine the role of miRNA in KPNA2 dysregulation. Our results showed that miR-26b was downregulated in EOC samples, and correlated inversely with KPNA2 expression. Low expression of miR-26b was associated with advanced FIGO stage, poor differentiation, higher risk of distant metastasis and recurrence. Downregulation of miR-26b predicted poor disease-free survival and overall survival in EOC patients. KPNA2 was validated as a direct target of miR-26b. Knockdown of KPNA2 or ectopic expression of miR-26b could downregulate OCT4, vimentin and upregulate E-cadherin. Reintroduction of KPNA2 partially abrogated the suppression effect induced by miR-26b. We further verified that miR-26b/KPNA2/OCT4 axis inhibited EOC cell viability, migratory ability and sphere-forming capacity in vitro and in vivo. In conclusion, our results reveal that miR-26b is downregulated in EOC, and directly targets KPNA2. miR-26b/KPNA2 axis suppresses tumor proliferation and metastasis through decreasing OCT4 expression, which is indicative of the important role of miR-26b/KPNA2/OCT4 axis in EOC carcinogenesis and progression.

Diniz MG, Silva Jde F, de Souza FT, et al.
Association between cell cycle gene transcription and tumor size in oral squamous cell carcinoma.
Tumour Biol. 2015; 36(12):9717-22 [PubMed] Related Publications
Higher tumor size correlates with poor prognosis and is an independent predictive survival factor in oral squamous cell carcinoma (OSCC) patients. However, the molecular events underlining OSCC tumor evolution are poorly understood. We aimed to investigate if large OSCC tumors show different cell cycle gene transcriptional signature compared to small tumors. Seventeen fresh OSCC tumor samples with different tumor sizes (T) were included in the study. Tumors were from the tongue or from the floor of the mouth, and only three patients were nonsmokers. Samples were categorized according to clinical tumor size in tumors ≤2 cm (T1, n = 5) or tumors >2 cm (T2, n = 9; T3, n = 2; T4, n = 1). The group of tumors ≤2 cm was considered the reference group, while the larger tumors were considered the test group. We assessed the expression of 84 cell cycle genes by qRT-PCR array and normalized it to the expression of two housekeeping genes. Results were analyzed according to the formula 2(^-DeltaCt). A five-fold change cutoff was used, and p values <0.05 were considered statistically significant. Ki-67 immunohistochemistry was performed to estimate cell proliferation index. Twenty-nine genes were downregulated in the test group (larger tumors) compared to the reference group (smaller tumors). Among these genes, 13 reached statistical significance: ANAPC4, CUL1, SUMO1, KPNA2, MAD2L2, CCNG2, E2F4, NBN, CUL2, PCNA, TFDP1, KNTC1, and ATR. Ki-67 labeling index was similar in both tumor groups. Our findings suggest that the transcriptional activity of specific cell cycle genes varies according to the size of OSCC tumor, which probably reflects tumor molecular evolution and adaptation to the microenvironment.

Fontemaggi G, Bellissimo T, Donzelli S, et al.
Identification of post-transcriptional regulatory networks during myeloblast-to-monocyte differentiation transition.
RNA Biol. 2015; 12(7):690-700 [PubMed] Free Access to Full Article Related Publications
Treatment of leukemia cells with 1,25-dihydroxyvitamin D3 may overcome their differentiation block and lead to the transition from myeloblasts to monocytes. To identify microRNA-mRNA networks relevant for myeloid differentiation, we profiled the expression of mRNAs and microRNAs associated to the low- and high-density ribosomal fractions in leukemic cells and in their differentiated monocytic counterpart. Intersection between mRNAs shifted across the fractions after treatment with putative target genes of modulated microRNAs showed a series of molecular networks relevant for the monocyte cell fate determination, as for example the post-transcriptional regulation of the Polo-like kinase 1 (PLK1) by miR-22-3p and let-7e-5p.

Shi B, Su B, Fang D, et al.
High expression of KPNA2 defines poor prognosis in patients with upper tract urothelial carcinoma treated with radical nephroureterectomy.
BMC Cancer. 2015; 15:380 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: To analyze the expression of karyopherin alpha 2 (KPNA2) in upper tract urothelial carcinoma (UTUC) and to investigate whether the KPNA2 expression provides additional prognostic information following radical nephroureterectomy (RNU).
METHODS: A tissue microarray (TMA) containing samples from 176 patients with UTUC who underwent RNU at our institute was analyzed for KPNA2 expression using immunohistochemistry. KPNA2 expression in normal urothelial cell line and urothelial carcinoma cell lines was evaluated by western blot analysis. Using RNA interference in vitro, the effects of KPNA2 inhibition on cellular viability, migration and apoptosis were determined.
RESULTS: KPNA2 expression was significantly upregulated in the UTUC samples compared with the adjacent normal urothelial tissues. High KPNA2 immunoreactivity was identified as a predictor of bladder recurrence (hazard ratio [HR]: 2.017, 95% CI 1.13-3.61, p = 0.018), poor disease-free survival (DFS, HR: 2.754, 95% CI 1.68-4.51, p = 0.001) and poor overall survival (OS, HR: 4.480, 95% CI 1.84-10.89, p = 0.001) for patients with UTUC after RNU. Furthermore, high KPNA2 immunoreactivity was independent of the conventional predictive factors in a multivariate analysis. Additional in vitro experiments revealed that KPNA2 expression was higher in urothelial carcinoma cell lines than in normal urothelial cell line. KPNA2 inhibition with a specific siRNA decreased cell viability and migration and increased apoptosis in urothelial carcinoma cell lines.
CONCLUSIONS: KPNA2 is a novel independent prognostic marker for bladder recurrence, DFS and OS of UTUC patients who have undergone RNU. Moreover, these data suggest that KPNA2 may be a promising therapeutic target for UTUC.

Al-Kaabi MM, Alshareeda AT, Jerjees DA, et al.
Checkpoint kinase1 (CHK1) is an important biomarker in breast cancer having a role in chemotherapy response.
Br J Cancer. 2015; 112(5):901-11 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Checkpoint kinase1 (CHK1), which is a key component of DNA-damage-activated checkpoint signalling response, may have a role in breast cancer (BC) pathogenesis and influence response to chemotherapy. This study investigated the clinicopathological significance of phosphorylated CHK1 (pCHK1) protein in BC.
METHOD: pCHK1 protein expression was assessed using immunohistochemistry in a large, well-characterized annotated series of early-stage primary operable invasive BC prepared as tissue microarray (n=1200).
RESULT: pCHK1 showed nuclear and/or cytoplasmic expression. Tumours with nuclear expression showed positive associations with favourable prognostic features such as lower grade, lower mitotic activity, expression of hormone receptor and lack of expression of KI67 and PI3K (P<0.001). On the other hand, cytoplasmic expression was associated with features of poor prognosis such as higher grade, triple-negative phenotype and expression of KI67, p53, AKT and PI3K. pCHK1 expression showed an association with DNA damage response (ATM, RAD51, BRCA1, KU70/KU80, DNA-PKCα and BARD1) and sumoylation (UBC9 and PIASγ) biomarkers. Subcellular localisation of pCHK1 was associated with the expression of the nuclear transport protein KPNA2. Positive nuclear expression predicted better survival outcome in patients who did not receive chemotherapy in the whole series and in ER-positive tumours. In ER-negative and triple-negative subgroups, nuclear pCHK1 predicted shorter survival in patients who received cyclophosphamide, methotrexate and 5-florouracil chemotherapy.
CONCLUSIONS: Our data suggest that pCHK1 may have prognostic and predictive significance in BC. Subcellular localisation of pCHK1 protein is related to its function.

Ma S, Zhao X
KPNA2 is a promising biomarker candidate for esophageal squamous cell carcinoma and correlates with cell proliferation.
Oncol Rep. 2014; 32(4):1631-7 [PubMed] Related Publications
Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignant cancers worldwide, with a poor 5-year prognosis. Karyopherin α 2 (KPNA2) is a nuclear membrane protein that mediates nucleus-to-cytoplasm shuttling. Its expression is elevated in multiple forms of cancer, and it can be secreted into the serum. However, the concentration of KPNA2 in serum from ESCC patients and the role of KPNA2 in ESCC cells remains unclear. The aim of the present study was to determine the concentration of KPNA2 in serum from ESCC patients and to investigate the effect of KPNA2 silencing on ESCC cell proliferation. KPNA2 protein expression was detected at the tissue level by immunohistochemistry, in cell lines by western blotting and at the serum level by enzyme linked immunosorbent assay (ELISA). Cell proliferation was determined by cell growth curve and colony formation assay. Stages of the cell cycle were analyzed by flow cytometry. The effect of KPNA2 knockdown on E2F1 translocation was determined by subcellular fractionation. KPNA2 was overexpressed in both ESCC tissues and cell lines compared with controls. The concentration of KPNA2 in serum from ESCC patients was significantly higher than that from healthy controls. The AUC was determined to be 0.804. The sensitivity and specificity of the assay were 76.7 and 75.0%, respectively. To determine the significance of KPNA2 function, small interfering RNA (siRNA) against KPNA2 was used to knock down KPNA2 levels in the ESCC using siRNA in the Kyse510 cell line. KPNA2 siRNA inhibited Kyse510 cell proliferation and colony formation ability and induced a G2/M phase arrest. The nuclear translocation of E2F1 was also reduced in siRNA-treated Kyse510 cells. The KPNA2 protein levels were high in ESCC tumors, and siRNA against KPNA2 could inhibit the growth of ESCC cells, suggesting it may be a new potent marker and therapeutic target for ESCC.

Hu ZY, Yuan SX, Yang Y, et al.
Pleomorphic adenoma gene 1 mediates the role of karyopherin alpha 2 and has prognostic significance in hepatocellular carcinoma.
J Exp Clin Cancer Res. 2014; 33:61 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Karyopherin alpha 2 (KPNA2) promotes tumor growth in hepatocellular carcinoma (HCC). We aimed to determine the content and clinical significance of mechanism underlying.
METHODS: The association of transcriptional factor pleomorphic adenoma gene 1 (PLAG1) with KPNA2 was explored by co-immunoprecipitation. In vitro gain- and loss-of-function models were established to explore the functional interaction. Clinical samples from 314 HCC patients were applied to explore the clinical significance.
RESULTS: We found that PLAG1 could associate with KPNA2 and be promoted into nucleus by KPNA2. The increment of proliferative and metastatic abilities by KPNA2 over-expression can be significantly retarded by PLAG1 inhibition. The co-enrichment of KPNA2 and PLAG1 in nucleus is observed in clinical samples and can distinguish patients with the worst prognosis. The positive PLAG1 expression is an independent risk factor of recurrence free survival (HR: 1.766, 1.315-2.371; P = 0.000) and overall survival (HR: 1.589, 1.138-2.220; P = 0.007). Especially for patients with positive KPNA2 staining (N = 152), the positive PLAG1 expression is the sole risk factor for both recurrence free survival (HR: 1.749, 1.146-2.670; P = 0.010) and overall survival (HR: 1.662, 1.007-2.744; P = 0.047).
CONCLUSIONS: The nuclear import of PLAG1 by KPNA2 is essential for the role of KPNA2 in HCC cells and is significant to predict poor survival of HCC patients after hepatectomy.

Yang S, Zhang H, Guo L, et al.
Reconstructing the coding and non-coding RNA regulatory networks of miRNAs and mRNAs in breast cancer.
Gene. 2014; 548(1):6-13 [PubMed] Related Publications
microRNAs (miRNAs) are a class of small non-coding RNAs that deregulate and/or decrease the expression of target messenger RNAs (mRNAs), which specifically contribute to complex diseases. In our study, we reanalyzed an integrated data to promote classification performance by rebuilding miRNA-mRNA modules, in which a group of deregulated miRNAs cooperatively regulated a group of significant mRNAs. In five-fold cross validation, the multiple processes flow considered the biological and statistical significant correlations. First, of statistical significant miRNAs, 6 were identified as core miRNAs. Second, in the 13 significant pathways enriched by gene set enrichment analysis (GSEA), 705 deregulated mRNAs were found. Based on the union of predicted sets and correlation sets, 6 modules were built. Finally, after verified by test sets, three indexes, including area under the ROC curve (AUC), Accuracy and Matthews correlation coefficients (MCCs), indicated only 4 modules (miR-106b-CIT-KPNA2-miR-93, miR-106b-POLQ-miR-93, miR-107-BTRC-UBR3-miR-16 and miR-200c-miR-16-EIF2B5-miR-15b) had discriminated ability and their classification performance were prior to that of the single molecules. By applying this flow to different subtypes, Module 1 was the consistent module across subtypes, but some different modules were still specific to each subtype. Taken together, this method gives new insight to building modules related to complex diseases and simultaneously can give a supplement to explain the mechanism of breast cancer (BC).

Gousias K, Niehusmann P, Gielen G, et al.
KPNA2 predicts long term survival in patients with anaplastic oligoastrocytomas.
J Clin Neurosci. 2014; 21(10):1719-24 [PubMed] Related Publications
The family of karyopherins comprises importins and exportins which are both involved in nucleocytoplasmic shuttling. Increased levels of karyopherin a2/importin 1 (KPNA2) and chromosome region maintenance protein 1/exportin 1 (CRM1) have been associated with poorer prognosis in patients with infiltrative astrocytomas. Isocitrate dehydrogenase 1 gene (IDH1) R132H mutation status was also recently identified as a prognostic factor for malignant gliomas. We evaluated KPNA2 and CRM1, as well as the IDH1 mutation status, as possible novel biomarkers for World Health Organization grade III anaplastic oligoastrocytomas (AOA). We analyzed nuclear expression of KPNA2 by immunohistochemistry in 72 primary anaplastic gliomas (29 AOA, 24 anaplastic astrocytomas, 19 anaplastic oligodendrogliomas). The IDH1 mutation status was also determined in patients with anaplastic astrocytomas and AOA, and AOA patients were additionally evaluated for CRM1 nuclear expression. Long term survivors (LTS; >8 years) with AOA showed lower KPNA2 expression levels compared to non-LTS (p=0.005). KPNA2 expression (⩾ 5% versus <5%, 1-<5%, median) was found to correlate inversely with overall survival (OS) and progression-free survival (PFS) in our overall series as well as in the AOA group (anaplastic gliomas: OS p=0.017; PFS p=0.033; AOA: OS p=0.017, PFS p=0.040). Mutant IDH1-R132H was detected in 69% of the AOA cohort; a combination of KPNA2 low expression and mutant IDH1-R132H was only seen in LTS (p=0.050). No differences between the histological subtypes were observed in terms of KPNA2 expression and IDH1-R132H mutation status. To our knowledge this is the first time it has been shown that KPNA2 expression may have potential as a prognostic biomarker for AOA as well.

Zhu YX, Braggio E, Shi CX, et al.
Identification of cereblon-binding proteins and relationship with response and survival after IMiDs in multiple myeloma.
Blood. 2014; 124(4):536-45 [PubMed] Free Access to Full Article Related Publications
Cereblon (CRBN) mediates immunomodulatory drug (IMiD) action in multiple myeloma (MM). Using 2 different methodologies, we identified 244 CRBN binding proteins and established relevance to MM biology by changes in their abundance after exposure to lenalidomide. Proteins most reproducibly binding CRBN (>fourfold vs controls) included DDB1, CUL4A, IKZF1, KPNA2, LTF, PFKL, PRKAR2A, RANGAP1, and SHMT2. After lenalidomide treatment, the abundance of 46 CRBN binding proteins decreased. We focused attention on 2 of these-IKZF1 and IKZF3. IZKF expression is similar across all MM stages or subtypes; however, IKZF1 is substantially lower in 3 of 5 IMiD-resistant MM cell lines. The cell line (FR4) with the lowest IKZF1 levels also harbors a damaging mutation and a translocation that upregulates IRF4, an IKZF target. Clinical relevance of CRBN-binding proteins was demonstrated in 44 refractory MM patients treated with pomalidomide and dexamethasone therapy in whom low IKZF1 gene expression predicted lack of response (0/11 responses in the lowest expression quartile). CRBN, IKZF1, and KPNA2 levels also correlate with significant differences in overall survival. Our study identifies CRBN-binding proteins and demonstrates that in addition to CRBN, IKZF1, and KPNA2, expression can predict survival outcomes.

Wang L, Huang J, Jiang M, et al.
CAMK1 phosphoinositide signal-mediated protein sorting and transport network in human hepatocellular carcinoma (HCC) by biocomputation.
Cell Biochem Biophys. 2014; 70(2):1011-6 [PubMed] Related Publications
We data-analyzed and constructed the high-expression CAMK1 phosphoinositide signal-mediated protein sorting and transport network in human hepatocellular carcinoma (HCC) compared with low-expression (fold change ≥ 2) no-tumor hepatitis/cirrhotic tissues (HBV or HCV infection) in GEO data set, using integration of gene regulatory network inference method with gene ontology (GO). Our result showed that CAMK1 transport subnetwork upstream KCNQ3, LCN2, NKX2_5, NUP62, SORT1, STX1A activated CAMK1, and downstream CAMK1-activated AFP, ENAH, KPNA2, SLC4A3; CAMK1 signal subnetwork upstream BRCA1, DKK1, GPSM2, LEF1, NR5A1, NUP62, SORT1, SSTR5, TBL3 activated CAMK1, and downstream CAMK1-activated MAP2K6, SFRP4, SSTR5, TSHB, UBE2C in HCC. We proposed that CAMK1 activated network enhanced endosome to lysosome transport, endosome transport via multivesicular body sorting pathway, Golgi to endosome transport, intracellular protein transmembrane transport, intracellular protein transport, ion transport, mRNA transport, plasma membrane to endosome transport, potassium ion transport, protein transport, vesicle-mediated transport, anion transport, intracellular transport, androgen receptor signaling pathway, cell surface receptor-linked signal transduction, hormone-mediated signaling, induction of apoptosis by extracellular signals, signal transduction by p53 class mediator resulting in transcription of p21 class mediator, signal transduction resulting in induction of apoptosis, phosphoinositide-mediated signaling, Wnt receptor signaling pathway, as a result of inducing phosphoinositide signal-mediated protein sorting, and transport in HCC. Our hypothesis was verified by CAMK1 functional regulation subnetwork containing positive regulation of calcium ion transport via voltage gated calcium channel, cell proliferation, DNA repair, exocytosis, I-kappaB kinase/NF-kappaB cascade, immunoglobulin-mediated immune response, mast cell activation, natural killer cell-mediated cytotoxicity directed against tumor cell target, protein ubiquitination, sodium ion transport, survival gene product activity, T cell-mediated cytotoxicity, transcription, transcription from RNA polymerase II promoter, transcription initiation from RNA polymerase II promoter, transcription via serum response element binding, exit from mitosis, ubiquitin ligase activity during mitotic cell cycle, regulation of angiogenesis, apoptosis, cell growth, cell proliferation, cyclin-dependent protein kinase activity, gene expression, insulin secretion, steroid biosynthesis, transcription from RNA polymerase II promoter, transcription from RNA polymerase III promoter, cell cycle, cell migration, DNA recombination, and protein metabolism; also by CAMK1 negative functional regulation subnetwork including negative regulation of apoptosis, cell proliferation, centriole replication, fatty acid biosynthesis, lipoprotein lipase activity, MAPK activity, progression through cell cycle, transcription, transcription from RNA polymerase II promoter, cell growth, phosphorylation, and ubiquitin ligase activity during mitotic cell cycle in HCC.

Pavlou MP, Dimitromanolakis A, Martinez-Morillo E, et al.
Integrating meta-analysis of microarray data and targeted proteomics for biomarker identification: application in breast cancer.
J Proteome Res. 2014; 13(6):2897-909 [PubMed] Related Publications
The development of signature biomarkers has gained considerable attention in the past decade. Although the most well-known examples of biomarker panels stem from gene expression studies, proteomic panels are becoming more relevant, with the advent of targeted mass spectrometry-based methodologies. At the same time, the development of multigene prognostic classifiers for early stage breast cancer patients has resulted in a wealth of publicly available gene expression data from thousands of breast cancer specimens. In the present study, we integrated transcriptome and proteome-based platforms to identify genes and proteins related to patient survival. Candidate biomarker proteins have been identified in a previously generated breast cancer tissue extract proteome. A mass-spectrometry-based assay was then developed for the simultaneous quantification of these 20 proteins in breast cancer tissue extracts. We quantified the relative expression levels of the 20 potential biomarkers in a cohort of 96 tissue samples from patients with early stage breast cancer. We identified two proteins, KPNA2 and CDK1, which showed potential to discriminate between estrogen receptor positive patients of high and low risk of disease recurrence. The role of these proteins in breast cancer prognosis warrants further investigation.

Gao R, Singh R, Kaul Z, et al.
Targeting of DNA Damage Signaling Pathway Induced Senescence and Reduced Migration of Cancer cells.
J Gerontol A Biol Sci Med Sci. 2015; 70(6):701-13 [PubMed] Related Publications
The heat shock 70 family protein, mortalin, has pancytoplasmic distribution pattern in normal and perinuclear in cancer human cells. Cancer cells when induced to senesce by either chemicals or stress showed shift in mortalin staining pattern from perinuclear to pancytoplasmic type. Using such shift in mortalin staining as a reporter, we screened human shRNA library and identified nine senescence-inducing siRNA candidates. An independent Comparative Genomic Hybridization analysis of 35 breast cancer cell lines revealed that five (NBS1, BRCA1, TIN2, MRE11A, and KPNA2) of the nine genes located on chromosome regions identified as the gain of locus in more than 80% cell lines. By gene-specific PCR, these five genes were found to be frequently amplified in cancer cell lines. Bioinformatics revealed that the identified targets were connected to MRN (MRE11-RAD50-NBS1) complex, the DNA damage-sensing complex. We demonstrate that the identified shRNAs triggered DNA damage response and induced the expression of tumor suppressor protein p16(INK4A) causing growth arrest of cancer cells. Furthermore, cells showed decreased migration, mediated by decrease in matrix metalloproteases. Taken together, we demonstrate that the MRN complex is a potential target of cancer cell proliferation and migration, and staining pattern of mortalin could serve as an assay to identify senescence-inducing/anticancer reagents.

Tan S, Ding K, Li R, et al.
Identification of miR-26 as a key mediator of estrogen stimulated cell proliferation by targeting CHD1, GREB1 and KPNA2.
Breast Cancer Res. 2014; 16(2):R40 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: Estrogen signaling is pivotal in the progression of estrogen receptor positive breast cancer primarily by the regulation of cell survival and proliferation. Micro (mi)RNAs have been demonstrated to be regulated by estrogen to mediate estrogenic effects. Herein, we determined the role of estrogen regulated miR-26 and its underlying molecular mechanisms associated with estrogen receptor (ER)+ breast cancer proliferation.
METHODS: The expression of miR-26a and miR-26b was evaluated by real-time quantitative (RT)-PCR. The expression of miR-26a or miR-26b was modulated in ER+ breast cancer cells (MCF-7 and T47D) and tumor cell growth in vitro and an in vivo xenograft model was determined. Bioinformatics analyses were utilized to screen for estrogen responsive genes, which were also predicted to be targeted by miR-26. Luciferase reporter assays were performed to confirm miR-26 regulation of the 3' UTR of target genes. The levels of miR-26 target genes (CHD1, GREB1 and KPNA2) were evaluated by western blotting and immunohistochemistry.
RESULTS: Estrogen reduced the expression of miR-26a and miR-26b in ER+ breast cancer cells. Forced expression of miR-26a or miR-26b significantly inhibited the estrogen stimulated growth of ER+ breast cancer cells and tumor growth in xenograft models, whereas miR-26a/b depletion increased the growth of ER+ breast cancer cells in the absence of estrogen treatment. Screening of estrogen responsive genes, which were also predicted to be targeted by miR-26, identified GREB1 and nine other genes (AGPAT5, AMMECR1, CHD1, ERLIN1, HSPA8, KPNA2, MREG, NARG1, and PLOD2). Further verification has identified nine genes (AGPAT5, CHD1, ERLIN1, GREB1, HSPA8, KPNA2, MREG, NARG1 and PLOD2) which were directly targeted by miR-26 via their 3' UTR. Functional screening suggested only three estrogen regulated miR-26 target genes (CHD1, GREB1 and KPNA2) were involved in the regulation of estrogen promoted cell proliferation. Depletion of either CHD1, GREB1 or KPNA2 significantly abrogated the enhanced growth of ER+ breast cancer cells due to miR-26 depletion. We further demonstrated that estrogen stimulated c-MYC expression was both sufficient and necessary for the diminished expression of miR-26a and miR-26b.
CONCLUSIONS: We have identified a novel estrogen/MYC/miR-26 axis that mediates estrogen stimulated cell growth via CHD1, GREB1 and KPNA2.

Alshareeda AT, Negm OH, Green AR, et al.
SUMOylation proteins in breast cancer.
Breast Cancer Res Treat. 2014; 144(3):519-30 [PubMed] Related Publications
Small Ubiquitin-like Modifier proteins (or SUMO) modify the function of protein substrates involved in various cellular processes including DNA damage response (DDR). It is becoming apparent that dysregulated SUMO contribute to carcinogenesis by affecting post-transcriptional modification of key proteins. It is hypothesised that SUMO contributes to the aggressive nature of breast cancer particularly those associated with features similar to breast carcinoma arising in patients with BRCA1 germline mutations. This study aims to assess the clinical and biological significance of three members of SUMO in a well-characterised annotated series of BC with emphasis on DDR. The study cohort comprised primary operable invasive BC including tumours from patients with known BRCA1 germline mutations. SUMO proteins PIAS1, PIAS4 and UBC9 were assessed using immunohistochemistry utilising tissue microarray technology. Additionally, their expression was assessed using reverse phase protein microarray utilising different cell lines. PIAS1 and UBC9 showed cytoplasmic and/or nuclear expression while PIAS4 was detected only in the nuclei. There was a correlation between subcellular localisation and expression of the nuclear transport protein KPNA2. Tumours showing positive nuclear/negative cytoplasmic expression of SUMO featured good prognostic characteristics including lower histologic grade and had a good outcome. Strong correlation with DDR-related proteins including BRCA1, Rad51, ATM, CHK1, DNA-PK and KU70/KU80 was observed. Correlation with ER and BRCA1 was confirmed using RPPA on cell lines. SUMO proteins seem to play important role in BC. Not only expression but also subcellular location is associated with BC phenotype.

Grupp K, Boumesli R, Tsourlakis MC, et al.
The prognostic impact of high Nijmegen breakage syndrome (NBS1) gene expression in ERG-negative prostate cancers lacking PTEN deletion is driven by KPNA2 expression.
Int J Cancer. 2014; 135(6):1399-407 [PubMed] Related Publications
The Nijmegen breakage syndrome (NBS1) gene was suggested as a prostate cancer susceptibility gene. This study was undertaken to determine, whether NBS1 expression is linked to clinically or molecularly relevant subgroups of prostate cancer. NBS1 expression was analyzed by immunohistochemistry on a tissue microarray containing 11,152 prostate cancer specimens. NBS1 expression was absent or only weakly detectable in benign prostate. In prostate cancers, NBS1 expression was found in 81.3% of interpretable tumors and was considered strong in 41.3% of cases. NBS1 upregulation was tightly linked to ERG-positive cancers (p<0.0001). Within ERG-negative cancers, strong NBS1 immunostaining was linked to advanced pathological tumor stage, high Gleason grade, and positive nodal status (p<0.0001 each), while high NBS1 immunostaining was only weakly associated with advanced pathological tumor stage in ERG-positive cancers (p=0.0099). A comparison with chromosomal deletions revealed a strong NBS1 upregulation in PTEN-deleted cancers, while deletions of 3p13, 5q21 and 6q15 did not affect NBS1 expression. High NBS1 expression was linked to biochemical recurrence in ERG-negative and PTEN non-deleted cancers (p<0.0001), which was largely driven by high KPNA2 karyopherin alpha 2 expression. In conclusion, our study identifies an association of NBS1 expression with surrogates of genomic instability in prostate cancer including TMPRSS2-ERG rearrangements and PTEN deletion. The prognostic impact of NBS1 expression in ERG-negative, PTEN non-deleted cancers was dependent of the expression status of its interaction partner KPNA2.

Li XL, Jia LL, Shi MM, et al.
Downregulation of KPNA2 in non-small-cell lung cancer is associated with Oct4 expression.
J Transl Med. 2013; 11:232 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Oct4 is a major transcription factor related to stem cell self-renewal and differentiation. To fulfill its functions, it must be able to enter the nucleus and remain there to affect transcription. KPNA2, a member of the karyopherin family, plays a central role in nucleocytoplasmic transport. The objective of the current study was to examine the association between Oct4 and KPNA2 expression levels with regard to both the clinicopathological characteristics and prognoses of patients with non-small-cell lung cancer (NSCLC).
METHODS: Immunohistochemistry was used to detect the expression profile of Oct4 and KPNA2 in NSCLC tissues and adjacent noncancerous lung tissues. Real-time polymerase chain reaction and western blotting were used to detect the mRNA and protein expression profiles of Oct4 and KPNA2 in lung cancer cell lines. Small interfering RNAs were used to deplete Oct4 and KPNA2 expressions. Double immunofluorescence was used to detect Oct4 expression in KPNA2 knockdown cells. Co-immunoprecipitation was used to detect the interaction of Oct4 and KPNA2.
RESULTS: Oct4 was overexpressed in 29 of 102 (28.4%) human lung cancer samples and correlated with differentiation (P = 0.002) and TNM stage (P = 0.003). KPNA2 was overexpressed in 56 of 102 (54.9%) human lung cancer samples and correlated with histology (P = 0.001) and differentiation (P = 0.045). Importantly, Oct4 and KPNA2 expression levels correlated significantly (P < 0.01). Expression of Oct4 and KPNA2 was associated with short overall survival. In addition, depleting Oct4 and KPNA2 expression using small interfering RNAs inhibited proliferation in lung cancer cell lines. Real-time polymerase chain reaction and western blotting analysis indicated that reduction of KPNA2 expression significantly reduced mRNA and nucleoprotein levels of Oct4. Double immunofluorescence analysis revealed that nuclear Oct4 signals were reduced significantly in KPNA2 knockdown cells. Co-immunoprecipitation experiments revealed that KPNA2 interacts with Oct4 in lung cancer cell lines.
CONCLUSION: Oct4 and KPNA2 play an important role in NSCLC progression. Oct4 nuclear localization may be mediated by its interaction with KPNA2.

Grupp K, Habermann M, Sirma H, et al.
High nuclear karyopherin α 2 expression is a strong and independent predictor of biochemical recurrence in prostate cancer patients treated by radical prostatectomy.
Mod Pathol. 2014; 27(1):96-106 [PubMed] Related Publications
Increased levels of karyopherin α2 (KPNA2) expression have been described to be linked to poor prognosis in a variety of malignancies. This study was undertaken to evaluate the clinical impact of KPNA2 expression and its association with key genomic alterations in prostate cancers. A tissue microarray containing samples from 11 152 prostate cancers was analyzed for KPNA2 expression by immunohistochemistry. Results were compared with oncological follow-up data and genomic alterations such as TMPRSS2-ERG fusions and deletions of PTEN, 5q21, 6q15 or 3p13. KPNA2 expression was absent or weak in benign prostatic glands and was found to be in weak, moderate or strong intensities in 68.4% of 7964 interpretable prostate cancers. KPNA2 positivity was significantly linked to the presence of ERG rearrangement (P<0.0001). In ERG-negative and -positive prostate cancers, KPNA2 immunostaining was significantly associated with advanced pathological tumor stage (pT3b/pT4), high Gleason grade and early biochemical recurrence (P<0.0001 each). Multivariate analysis including all established prognostic criteria available after surgery revealed that the prognostic role of KPNA2 (P=0.001) was independent of high Gleason grade, advanced pathological tumor stage, high preoperative prostate-specific antigen level and positive surgical margin status (P<0.0001 each). The comparison of KPNA2 expression with deletions of PTEN, 5q21, 6q15 and 3p13 in ERG-positive and -negative cancers revealed a strong link to PTEN deletions in both subgroups (P<0.0001). In conclusion, the strong independent prognostic impact of KPNA2 expression raises the possibility that measurement of KPNA2 expression alone or in combination with other molecular parameters might possibly result in clinically useful information. The data also emphasize a critical role of the functionality of the nuclear import machinery for prostate cancer biology.

Altan B, Yokobori T, Mochiki E, et al.
Nuclear karyopherin-α2 expression in primary lesions and metastatic lymph nodes was associated with poor prognosis and progression in gastric cancer.
Carcinogenesis. 2013; 34(10):2314-21 [PubMed] Related Publications
Karyopherin-α2 (KPNA2) functions as an adaptor that transports several proteins to the nucleus. We investigated the clinical and functional significance of KPNA2 in gastric cancer (GC). Immunohistochemistry was performed to examine KPNA2 expression in primary GC and metastatic lymph nodes. Next, KPNA2 was suppressed by small interfering RNA (siRNA) to examine KPNA2 function in proliferation and cisplatin-induced apoptosis of GC cell lines. Nuclear expression of KPNA2 in marginal regions of primary GC was stronger than in central regions of GC and normal tissues. The high expression of marginal KPNA2 was significantly associated with β-catenin accumulation in the nucleus and poor prognosis in two independent GC cohorts (discovery cohort, n = 90, P = 0.018; validation cohort, n = 89, P = 0.0125). We detected correlations between nuclear KPNA2 expression in marginal region and progression of macroscopic type (P = 0.036), tumor depth (P = 0.013), lymph node metastasis (P = 0.0064), venous invasion (P = 0.034) and clinical stage (P = 0.0006). Nuclear KPNA2 expression in marginal regions of metastatic lymph nodes was significantly higher than in the central region. It was associated with poor survival of GC patients with lymph node metastasis (n = 96; center, P = 0.4384; marginal, P < 0.0001). KPNA2 suppression enhanced cisplatin-induced apoptosis and reduced proliferation in the KPNA2 siRNA group compared with the control siRNA group. The expression of the DNA repair gene NBS1 (NBN) in the nucleus was suppressed in KPNA2-suppressed cells. KPNA2 might be a useful prognostic marker and an effective therapeutic target for GC.

Rachidi SM, Qin T, Sun S, et al.
Molecular profiling of multiple human cancers defines an inflammatory cancer-associated molecular pattern and uncovers KPNA2 as a uniform poor prognostic cancer marker.
PLoS One. 2013; 8(3):e57911 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Immune evasion is one of the recognized hallmarks of cancer. Inflammatory responses to cancer can also contribute directly to oncogenesis. Since the immune system is hardwired to protect the host, there is a possibility that cancers, regardless of their histological origins, endow themselves with a common and shared inflammatory cancer-associated molecular pattern (iCAMP) to promote oncoinflammation. However, the definition of iCAMP has not been conceptually and experimentally investigated.
METHODS AND FINDINGS: Genome-wide cDNA expression data was analyzed for 221 normal and 324 cancer specimens from 7 cancer types: breast, prostate, lung, colon, gastric, oral and pancreatic. A total of 96 inflammatory genes with consistent dysregulation were identified, including 44 up-regulated and 52 down-regulated genes. Protein expression was confirmed by immunohistochemistry for some of these genes. The iCAMP contains proteins whose roles in cancer have been implicated and others which are yet to be appreciated. The clinical significance of many iCAMP genes was confirmed in multiple independent cohorts of colon and ovarian cancer patients. In both cases, better prognosis correlated strongly with high CXCL13 and low level of GREM1, LOX, TNFAIP6, CD36, and EDNRA. An "Inflammatory Gene Integrated Score" was further developed from the combination of 18 iCAMP genes in ovarian cancer, which predicted overall survival. Noticeably, as a selective nuclear import protein whose immuno-regulatory function just begins to emerge, karyopherin alpha 2 (KPNA2) is uniformly up-regulated across cancer types. For the first time, the cancer-specific up-regulation of KPNA2 and its clinical significance were verified by tissue microarray analysis in colon and head-neck cancers.
CONCLUSION: This work defines an inflammatory signature shared by seven epithelial cancer types and KPNA2 as a consistently up-regulated protein in cancer. Identification of iCAMP may not only serve as a novel biomarker for prognostication and individualized treatment of cancer, but also have significant biological implications.

He L, Ding H, Wang JH, et al.
Overexpression of karyopherin 2 in human ovarian malignant germ cell tumor correlates with poor prognosis.
PLoS One. 2012; 7(9):e42992 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The aim of this study was to identify a biomarker useful in the diagnosis and therapy of ovarian malignant germ cell tumor (OMGCT).
METHODS: The karyopherin 2 (KPNA2) expression in OMGCT and normal ovarian tissue was determined by standard gene microarray assays, and further validated by a quantitative RT-PCR and immunohistochemistry. The correlation between KPNA2 expression in OMGCT and certain clinicopathological features were analyzed. Expression of SALL4, a stem cell marker, was also examined in comparison with KPNA2.
RESULTS: KPNA2 was found to be over-expressed by approximately eight-fold in yolk sac tumors and immature teratomas compared to normal ovarian tissue by microarray assays. Overexpression was detected in yolk sac tumors, immature teratomas, dysgerminomas, embryonal carcinomas, mature teratomas with malignant transformation and mixed ovarian germ cell tumors at both the transcription and translation levels. A positive correlation between KPNA2 and SALL4 expression at both the transcription level (R = 0.5120, P = 0.0125), and the translation level (R = 0.6636, P<0.0001), was presented. Extensive expression of KPNA2 was positively associated with pathologic type, recurrence and uncontrolled, ascitic fluid presence, suboptimal cytoreductive surgery necessity, resistance/refraction to initial chemotherapy, HCG level and SALL4 level in OMGCT patients. KPNA2 was found to be an independent factor for 5-year disease-free survival (DFS) of OMGCT (P = 0.02). The 5-year overall survival (OS) and DFS rate for KPNA2-low expression patients (88% and 79%, n = 48) were significantly higher than the OS and DFS rate for KPNA2-high expression patients (69% and 57.1%, n = 42)(P = 0.0151, P = 0.0109, respectively). The 5-year OS and DFS rate for SALL4-low expression patients (84% and 74%, n = 62) was marginally significantly higher than the high expression patients (78.6% and 71.4%, n = 28)(P = 0.0519, P = 0.0647, respectively).
CONCLUSIONS: KPNA2 is a potential candidate molecular marker and important prognostic marker in OMGCT patients.

Wang CI, Chien KY, Wang CL, et al.
Quantitative proteomics reveals regulation of karyopherin subunit alpha-2 (KPNA2) and its potential novel cargo proteins in nonsmall cell lung cancer.
Mol Cell Proteomics. 2012; 11(11):1105-22 [PubMed] Free Access to Full Article Related Publications
The process of nucleocytoplasmic shuttling is mediated by karyopherins. Dysregulated expression of karyopherins may trigger oncogenesis through aberrant distribution of cargo proteins. Karyopherin subunit alpha-2 (KPNA2) was previously identified as a potential biomarker for nonsmall cell lung cancer by integration of the cancer cell secretome and tissue transcriptome data sets. Knockdown of KPNA2 suppressed the proliferation and migration abilities of lung cancer cells. However, the precise molecular mechanisms underlying KPNA2 activity in cancer remain to be established. In the current study, we applied gene knockdown, subcellular fractionation, and stable isotope labeling by amino acids in cell culture-based quantitative proteomic strategies to systematically analyze the KPNA2-regulating protein profiles in an adenocarcinoma cell line. Interaction network analysis revealed that several KPNA2-regulating proteins are involved in the cell cycle, DNA metabolic process, cellular component movements and cell migration. Importantly, E2F1 was identified as a potential novel cargo of KPNA2 in the nuclear proteome. The mRNA levels of potential effectors of E2F1 measured using quantitative PCR indicated that E2F1 is one of the "master molecule" responses to KPNA2 knockdown. Immunofluorescence staining and immunoprecipitation assays disclosed co-localization and association between E2F1 and KPNA2. An in vitro protein binding assay further demonstrated that E2F1 interacts directly with KPNA2. Moreover, knockdown of KPNA2 led to subcellular redistribution of E2F1 in lung cancer cells. Our results collectively demonstrate the utility of quantitative proteomic approaches and provide a fundamental platform to further explore the biological roles of KPNA2 in nonsmall cell lung cancer.

van der Watt PJ, Ngarande E, Leaner VD
Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.
PLoS One. 2011; 6(11):e27723 [PubMed] Free Access to Full Article Related Publications
The Karyopherin superfamily comprises nuclear transport proteins, involved in the shuttling of certain cargo proteins into and out of the nucleus. Karyopherin β1 (Kpnβ1) and Karyopherin α2 (Kpnα2) are importin proteins, which work in concert to transport their cargo into the nucleus. We previously identified increased expression of Kpnβ1 and Kpnα2 in cervical tumours compared to normal epithelium and in transformed cells compared to their normal counterparts. This study therefore aimed to identify the transcription regulatory mechanisms associated with high Kpnβ1 and Kpnα2 levels in cancer cells. Kpnβ1 (-2013 to +100) and Kpnα2 (-1900 to +69) promoter fragments were separately cloned into the reporter vector, pGL3-basic, and luciferase assays revealed both as significantly more active in cancer and transformed cells compared to normal. A series of deletion constructs identified the -637 to -271 Kpnβ1 and -180 to -24 Kpnα2 promoter regions as responsible for the differential promoter activity, and a number of highly conserved E2F binding sites were identified within these regions. Mutation analysis confirmed the requirement of E2F sites for promoter activity, and ChIP analysis confirmed E2F2/Dp1 binding to the Kpnβ1 and Kpnα2 promoters in vivo. Dp1 inhibition resulted in decreased levels of the respective proteins, confirming the role of E2F in the overexpression of Kpnβ1 and Kpnα2 proteins in cancer. E2F activity is known to be deregulated in cervical cancer cells due to the inhibition of its repressor, Rb, by HPV E7. The inhibition of E7 using siRNA resulted in decreased Kpnβ1 and Kpnα2 promoter activities, as did the overexpression of Rb. In conclusion, this study is a first to show that elevated Kpnβ1 and Kpnα2 expression in cancer cells correlates with altered transcriptional regulation associated with deregulated E2F/Rb activities.

Mortezavi A, Hermanns T, Seifert HH, et al.
KPNA2 expression is an independent adverse predictor of biochemical recurrence after radical prostatectomy.
Clin Cancer Res. 2011; 17(5):1111-21 [PubMed] Related Publications
PURPOSE: To analyze rates of expression of karyopherin alpha 2 (KPNA2) in different prostate tissues and to evaluate the prognostic properties for patients with primary prostate cancer.
EXPERIMENTAL DESIGN: Tissue microarrays (TMA) contained 798 formalin-fixed, paraffin-embedded prostate tissue cores from two different institutes of pathology. TMAs were stained immunohistochemically for KPNA2 and NBS1. SiRNA technologies were used to inhibit KPNA2 expression in vitro, and the effect of this inhibition on cellular viability was determined. Efficiency of knockdown experiments was determined by Western blot analysis.
RESULTS: KPNA2 expression was significantly upregulated in carcinomas of the prostate, especially in metastatic and castration-resistant prostate cancer samples. Positive nuclear KPNA2 immunoreactivity was identified as a novel predictor of biochemical recurrence after radical prostatectomy (n = 348), and was independent of the well-established predictive factors preoperative PSA value, Gleason score, tumor stage, and surgical margin status. These results were validated by analyzing a second and independent prostate cancer cohort (n = 330). Further, in vitro experiments showed that the cell proliferation and viability of PC3 cells was significantly reduced when KPNA2 expression was inhibited. KPNA2 knockdown did not induce PARP cleavage as marker for apoptosis. No significantly increased sub-G(1) fraction could be found by FACS analysis.
CONCLUSIONS: KPNA2 is a novel independent prognostic marker for disease progression after radical prostatectomy. This allows to identify patients who need more aggressive treatment. It can moreover be speculated that patients not suited for surveillance regimens might be identified at initial biopsy by a positive KPNA2 immunohistochemistry.

Jiang J, Sliva D
Novel medicinal mushroom blend suppresses growth and invasiveness of human breast cancer cells.
Int J Oncol. 2010; 37(6):1529-36 [PubMed] Related Publications
Mushrooms are an integral part of Traditional Chinese Medicine (TCM), and have been used for millennia to prevent or treat a variety of diseases. Currently mushrooms or their extracts are used globally in the form of dietary supplements. In the present study we have evaluated the anticancer effects of the dietary supplement, MycoPhyto® Complex (MC), a novel medicinal mushroom blend which consists of a blend of mushroom mycelia from the species Agaricus blazei, Cordyceps sinensis, Coriolus versicolor, Ganoderma lucidum, Grifola frondosa and Polyporus umbellatus, and β-1,3-glucan isolated from the yeast, Saccharomyces cerevisiae. Here, we show that MC demonstrates cytostatic effects through the inhibition of cell proliferation and cell cycle arrest at the G2/M phase of highly invasive human breast cancer cells MDA-MB-231. DNA-microarray analysis revealed that MC inhibits expression of cell cycle regulatory genes (ANAPC2, ANAPC2, BIRC5, Cyclin B1, Cyclin H, CDC20, CDK2, CKS1B, Cullin 1, E2F1, KPNA2, PKMYT1 and TFDP1). Moreover, MC also suppresses the metastatic behavior of MDA-MB-231 by the inhibition of cell adhesion, cell migration and cell invasion. The potency of MC to inhibit invasiveness of breast cancer cells is linked to the suppression of secretion of the urokinase plasminogen activator (uPA) from MDA-MB-231 cells. In conclusion, the MC dietary supplement could have potential therapeutic value in the treatment of invasive human breast cancer.

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