Gene Summary

Gene:PRKCD; protein kinase C delta
Aliases: MAY1, PKCD, ALPS3, CVID9, nPKC-delta
Summary:The protein encoded by this gene is a member of the protein kinase C family of serine- and threonine-specific protein kinases. The encoded protein is activated by diacylglycerol and is both a tumor suppressor and a positive regulator of cell cycle progression. Also, this protein can positively or negatively regulate apoptosis. Defects in this gene are a cause of autoimmune lymphoproliferative syndrome. [provided by RefSeq, Aug 2017]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:protein kinase C delta type
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
Show (66)
Pathways:What pathways are this gene/protein implicaed in?
Show (6)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 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.

  • Carrier Proteins
  • Cell Survival
  • Melanoma
  • Cancer RNA
  • Signal Transduction
  • Xenograft Models
  • RNA Interference
  • Ubiquitin-Protein Ligase Complexes
  • Extracellular Signal-Regulated MAP Kinases
  • Cancer Gene Expression Regulation
  • Neoplasm Proteins
  • Trastuzumab
  • Breast Cancer
  • bcl-X Protein
  • Histiocytoma, Benign Fibrous
  • Transcriptional Activation
  • p53 Protein
  • src-Family Kinases
  • Tetraspanin 30
  • Chromosome 3
  • Mutation
  • Phosphorylation
  • MicroRNAs
  • Up-Regulation
  • Tyrosine
  • Transcription
  • Protein Kinase C
  • Translocation
  • Drug Resistance
  • Western Blotting
  • Dose-Response Relationship, Drug
  • Tetradecanoylphorbol Acetate
  • Protein Kinase C-delta
  • Isoenzymes
  • Antineoplastic Agents
  • Apoptosis
  • Cervical Cancer
  • Tumor Escape
  • Tissue Fixation
  • Transfection
  • Enzyme Activation
Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

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: PRKCD (cancer-related)

Yang F, Qiu W, Li R, et al.
Genome-wide identification of the interactions between key genes and pathways provide new insights into the toxicity of bisphenol F and S during early development in zebrafish.
Chemosphere. 2018; 213:559-567 [PubMed] Related Publications
Bisphenol F (BPF) and bisphenol S (BPS) have been widely used as alternatives to bisphenol A (BPA). With their increasing use, BPF and BPS have also been released into the environment; thus, their potential risks to aquatic organisms and humans are drawing attention. The objective of this study was to identify the interactions between key pathways and hub genes in zebrafish following BPF and BPS exposure, and to evaluate the potential risks to human health. We identified three key pathways using KEGG over-representation test and Gene Set Enrichment Analysis (GSEA): 'Necroptosis,' 'Adipocytokine signaling pathway,' and 'C-type lectin receptor signaling pathway.' Moreover, three hub genes (mst1ra, prkcdb, and pik3cb) and detailed interactions among the pathways were examined by the analyses of PPI network, subcellular location, and shortest-pathway. Surprisingly, all three pathways were strongly associated with a potential risk of cancer, as reported previously. In addition, the results of KOBAS shown in 'Pathways in Cancer' and 'Cancers' belong to the top 10 terms in pathway enrichment analyses using genes related to BPF or BPS in human, as was found using GenCLiP. Moreover, the Kaplan-Meier survival analysis was performed using homologenes (MST1R, PIK3CB and PRKCD) of hub genes in human to evaluate whether exposure to bisphenols may adversely affect breast cancer. Taken together, these studies demonstrate the potential carcinogenicity of BPF and BPS. To our knowledge, this is the first study on three overlapping key pathways and three hub genes to investigate BPF and BPS exposure-related mechanisms and subsequent interactions in zebrafish.

Lan J, Lu H, Samanta D, et al.
Hypoxia-inducible factor 1-dependent expression of adenosine receptor 2B promotes breast cancer stem cell enrichment.
Proc Natl Acad Sci U S A. 2018; 115(41):E9640-E9648 [PubMed] Free Access to Full Article Related Publications
Breast cancer stem cells (BCSCs), which are characterized by a capacity for unlimited self-renewal and for generation of the bulk cancer cell population, play a critical role in cancer relapse and metastasis. Hypoxia is a common feature of the cancer microenvironment that stimulates the specification and maintenance of BCSCs. In this study, we found that hypoxia increased expression of adenosine receptor 2B (A2BR) in human breast cancer cells through the transcriptional activity of hypoxia-inducible factor 1. The binding of adenosine to A2BR promoted BCSC enrichment by activating protein kinase C-δ, which phosphorylated and activated the transcription factor STAT3, leading to increased expression of interleukin 6 and NANOG, two key mediators of the BCSC phenotype. Genetic or pharmacological inhibition of A2BR expression or activity decreased hypoxia- or adenosine-induced BCSC enrichment in vitro, and dramatically impaired tumor initiation and lung metastasis after implantation of MDA-MB-231 human breast cancer cells into the mammary fat pad of immunodeficient mice. These data provide evidence that targeting A2BR might be an effective strategy to eradicate BCSCs.

Mazzio EA, Soliman KFA
Whole-transcriptomic Profile of SK-MEL-3 Melanoma Cells Treated with the Histone Deacetylase Inhibitor: Trichostatin A.
Cancer Genomics Proteomics. 2018 Sep-Oct; 15(5):349-364 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Malignant melanoma cells can rapidly acquire phenotypic properties making them resistant to radiation and mainline chemotherapies such as decarbonize or kinase inhibitors that target RAS-proto-oncogene independent auto-activated mitogen-activated protein kinases (MAPK)/through dual specificity mitogen-activated protein kinase (MEK). Both drug resistance and inherent transition from melanocytic nevi to malignant melanoma involve the overexpression of histone deacetylases (HDACs) and a B-Raf proto-oncogene (BRAF) mutation.
MATERIALS AND METHODS: In this work, the effects of an HDAC class I and II inhibitor trichostatin A (TSA) on the whole transcriptome of SK-MEL-3 cells carrying a BRAF mutation was examined.
RESULTS: The data obtained show that TSA was an extremely potent HDAC inhibitor within SK-MEL-3 nuclear lysates, where TSA was then optimized for appropriate sub-lethal concentrations for in vitro testing. The whole-transcriptome profile shows a basic phenotype dominance in the SK-MEL-3 cell line for i) synthesis of melanin, ii) phagosome acidification, iii) ATP hydrolysis-coupled proton pumps and iv) iron transport systems. While TSA did not affect the aforementioned major systems, it evoked a dramatic change to the transcriptome: reflected by a down-regulation of 810 transcripts and up-regulation of 833, with fold-change from -15.27 to +31.1 FC (p<0.00001). Largest differentials were found for the following transcripts: Up-regulated: Tetraspanin 13 (TSPAN13), serpin family i member 1 (SERPINI1), ATPase Na+/K+ transporting subunit beta 2 (ATP1B2), nicotinamide nucleotide adenylyl transferase 2 (NMNAT2), platelet-derived growth factor receptor-like (PDGFRL), cytochrome P450 family 1 subfamily A member 1 (CYP1A1), prostate androgen-regulated mucin-like protein 1 (PARM1), secretogranin II (SCG2), SYT11 (synaptotagmin 11), rhophilin associated tail protein 1 like (ROPN1L); down-regulated: polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3), carbonic anhydrase 14 (CAXIV), BCL2-related protein A1 (BCL2A1), protein kinase C delta (PRKCD), transient receptor potential cation channel subfamily M member 1 (TRPM1), ubiquitin associated protein 1 like (UBAP1L), glutathione peroxidase 8 (GPX8), interleukin 16 (IL16), tumor protein p53 (TP53), and serpin family H member 1 (SERPINH1). There was no change to any of the HDAC transcripts (class I, II and IV), the sirtuin HDAC family (1-6) or the BRAF proto-oncogene v 599 transcripts. However, the data showed that TSA down-regulated influential transcripts that drive the BRAF-extracellular signal-regulated kinase (ERK)1/2 oncogenic pathway (namely PRKCD and MYC proto-oncogene which negatively affected the cell-cycle distribution. Mitotic inhibition was corroborated by functional pathway analysis and flow cytometry confirming halt at the G
CONCLUSION: TSA does not alter HDAC transcripts nor BRAF itself, but down-regulates critical components of the MAPK/MEK/BRAF oncogenic pathway, initiating a mitotic arrest.

Feng X, Zhang C, Yang Y, et al.
Role of miR-181a in the process of apoptosis of multiple malignant tumors: A literature review.
Adv Clin Exp Med. 2018; 27(2):263-270 [PubMed] Related Publications
It has been recognized that miR-181a expression is dysregulated and intimately associated with clinical prognosis in a variety of human cancers. However, the direct role of miR-181a in tumor progression has been elusive. Moreover, mounting evidence has demonstrated that cellular apoptosis, a physiological process of programmed cell death, is disrupted in various categories of human malignancies. Multiple apoptosisrelated genes have been proven to act as the target genes of miR-181a. In this study, we hypothesize that miR-181a probably plays a potential role in modulating the procession and apoptosis of cancer cells. We performed a literature review and elucidated how miR-181a modulated cellular apoptosis, especially the malignant neoplasm cells. We also unraveled the potential role of miR-181a in the diagnosis, treatment and clinical prognosis of multiple human malignancies - miR-181a plays a pivotal role in the development, treatment and prognosis of patients suffering from malignant tumors. It also participates in the development of cancer partially by modulating cellular apoptosis.

Singh R, Dagar P, Pal S, et al.
Significant alterations of the novel 15 gene signature identified from macrophage-tumor interactions in breast cancer.
Biochim Biophys Acta Gen Subj. 2018; 1862(3):669-683 [PubMed] Related Publications
BACKGROUND: Tumor microenvironment is composed of a largely altered extracellular matrix with different cell types. The complex interplay between macrophages and tumor cells through several soluble factors and signaling is an important factor in breast cancer progression.
METHODS: We have extended our earlier studies on monocyte and macrophage conditioned medium (MϕCM) and have carried out proteomic analysis to identify its constituents as well as validation. The 8-gene signature identified through macrophage-breast cancer cell interactions was queried in cBioportal for bioinformatic analyses.
RESULTS: Proteomic analysis (MALDI-TOF and LC-MS/MS) revealed integrin and matrix metalloproteinases in MϕCM which activated TGF-β1, IL-6, TGF- βRII and EGFR as well as its downstream STAT and SMAD signaling in breast cancer cells. Neutralization of pro-inflammatory cytokines (TNF-α. Il-1β, IL-6) abrogated the MϕCM induced migration but invasion to lesser extent. The 8- gene signature identified by macrophage-tumor interactions (TNF-α, IL-1β, IL-6, MMP1, MMP9, TGF-β1, TGF-βRII, EGFR) significantly co-occurred with TP53 mutation, WTAPP1 deletion and SLC12A5 amplification along with differential expression of PSAT1 and ESR1 at the mRNA level and TPD52and PRKCD at the protein level in TCGA (cBioportal). Together these genes form a novel 15 gene signature which is altered in 63.6% of TCGA (1105 samples) data and was associated with high risk and poor survival (p<0.05) in many breast cancer datasets (SurvExpress).
CONCLUSIONS: These results highlight the importance of macrophage signaling in breast cancer and the prognostic role of the15-gene signature.
GENERAL SIGNIFICANCE: Our study may facilitate novel prognostic markers based on tumor-macrophage interaction.

Wang CQ, Huang YW, Wang SW, et al.
Amphiregulin enhances VEGF-A production in human chondrosarcoma cells and promotes angiogenesis by inhibiting miR-206 via FAK/c-Src/PKCδ pathway.
Cancer Lett. 2017; 385:261-270 [PubMed] Related Publications
Chondrosarcoma is the second most common primary malignancy of bone after myeloma and osteosarcoma. Chondrosarcoma development may be linked to angiogenesis, which is principally elicited by vascular endothelial growth factor-A (VEGF-A). The expression of VEGF-A has been recognized as a prognostic marker in angiogenesis. Amphiregulin (AR), an epidermal growth factor receptor ligand, promotes tumor proliferation, metastasis and angiogenesis. However, the role of AR in VEGF-A expression and angiogenesis in human chondrosarcoma remains largely unknown. This current study shows that AR promoted VEGF-A production and induced angiogenesis of human endothelial progenitor cells. Moreover, AR-enhanced VEGF-A expression and angiogenesis involved the FAK, c-Src and PKCδ signaling pathways, while miR-206 expression was negatively mediated by AR via the FAK, c-Src and PKCδ pathways. Our results illustrate the clinical significance between AR, VEGF-A and miR-206, as well as tumor stage, in human chondrosarcoma. AR may represent a novel therapeutic target in the metastasis and angiogenesis of chondrosarcoma.

Shapiro BA, Vu NT, Shultz MD, et al.
Melanoma Differentiation-associated Gene 7/IL-24 Exerts Cytotoxic Effects by Altering the Alternative Splicing of Bcl-x Pre-mRNA via the SRC/PKCδ Signaling Axis.
J Biol Chem. 2016; 291(41):21669-21681 [PubMed] Free Access to Full Article Related Publications
Melanoma differentiation-associated gene 7 (MDA-7/IL-24) exhibits cytotoxic effects on tumor cells while sparing untransformed cells, and Bcl-x(L) is reported to efficiently block the induction of cell death by MDA-7/IL-24. The expression of Bcl-x(L) is regulated at the level of RNA splicing via alternative 5' splice site selection within exon 2 to produce either the pro-apoptotic Bcl-x(s) or the anti-apoptotic Bcl-x(L). Our laboratory previously reported that Bcl-x RNA splicing is dysregulated in a large percentage of human non-small cell lung cancer (NSCLC) tumors. Therefore, we investigated whether the alternative RNA splicing of Bcl-x pre-mRNA was modulated by MDA-7/IL-24, which would suggest that specific NSCLC tumors are valid targets for this cytokine therapy. Adenovirus-delivered MDA-7/IL-24 (Ad.mda-7) reduced the viability of NSCLC cells of varying oncogenotypes, which was preceded by a decrease in the ratio of Bcl-x(L)/Bcl-x(s) mRNA and Bcl-x(L) protein expression. Importantly, both the expression of Bcl-x(L) and the loss of cell viability were "rescued" in Ad.mda-7-treated cells incubated with Bcl-x(s) siRNA. In addition, NSCLC cells ectopically expressing Bcl-x(s) exhibited significantly reduced Bcl-x(L) expression, which was again restored by Bcl-x(s) siRNA, suggesting the existence of a novel mechanism by which Bcl-x(s) mRNA restrains the expression of Bcl-x(L). In additional mechanistic studies, inhibition of SRC and PKCδ completely ablated the ability of MDA-7/IL-24 to reduce the Bcl-x(L)/(s) mRNA ratio and cell viability. These findings show that Bcl-x(s) expression is an important mediator of MDA-7/IL-24-induced cytotoxicity requiring the SRC/PKCδ signaling axis in NSCLC cells.

Dashzeveg N, Yoshida K
Crosstalk between tumor suppressors p53 and PKCδ: Execution of the intrinsic apoptotic pathways.
Cancer Lett. 2016; 377(2):158-63 [PubMed] Related Publications
p53 and PKCδ are tumor suppressors that execute apoptotic mechanisms in response to various cellular stresses. p53 is a transcription factor that is frequently mutated in human cancers; it regulates apoptosis in transcription-dependent and -independent ways in response to genotoxic stresses. PKCδ is a serine/threonine protein kinase and mutated in human cancers. Available evidence shows that PKCδ activates p53 by direct and/or indirect mechanisms. Moreover, PKCδ is also implicated in the transcriptional regulation of p53 in response to DNA damage. Recent findings demonstrated that p53, in turn, binds onto the PKCδ promoter and induces its expression upon DNA damage to facilitate apoptosis. Both p53 and PKCδ are associated with the apoptotic mechanisms in the mitochondria by regulating Bcl-2 family proteins to provide mitochondrial outer membrane permeabilization. This review discusses the crosstalk between p53 and PKCδ in the context of apoptotic cell death and cancer therapy.

Lim B, Kim C, Kim JH, et al.
Genetic alterations and their clinical implications in gastric cancer peritoneal carcinomatosis revealed by whole-exome sequencing of malignant ascites.
Oncotarget. 2016; 7(7):8055-66 [PubMed] Free Access to Full Article Related Publications
Peritoneal carcinomatosis accompanied by malignant ascites is a major cause of death of advanced gastric cancer (GC). To comprehensively characterize the underlying genomic events involved in GC peritoneal carcinomatosis, we analyzed whole-exome sequences of normal gastric tissues, primary tumors, and malignant ascites from eight GC patients. We identified a unique mutational signature biased toward C-to-A substitutions in malignant ascites. In contrast, the patients who received treatment of adjuvant chemotherapy showed a high rate of C-to-T substitutions along with hypermutation in malignant ascites. Comparative analysis revealed several candidate mutations for GC peritoneal carcinomatosis: recurrent mutations in COL4A6, INTS2, and PTPN13; mutations in druggable genes including TEP1, PRKCD, BRAF, ERBB4, PIK3CA, HDAC9, FYN, FASN, BIRC2, FLT3, ROCK1, CD22, and PIK3C2B; and mutations in metastasis-associated genes including TNFSF12, L1CAM, DIAPH3, ROCK1, TGFBR1, MYO9B, NR4A1, and RHOA. Notably, gene ontology analysis revealed the significant enrichment of mutations in the Rho-ROCK signaling pathway-associated biological processes in malignant ascites. At least four of the eight patients acquired somatic mutations in the Rho-ROCK pathway components, suggesting the possible relevance of this pathway to GC peritoneal carcinomatosis. These results provide a genome-wide molecular understanding of GC peritoneal carcinomatosis and its clinical implications, thereby facilitating the development of effective therapeutics.

Gentilin E, Di Pasquale C, Gagliano T, et al.
Protein Kinase C Delta restrains growth in ACTH-secreting pituitary adenoma cells.
Mol Cell Endocrinol. 2016; 419:252-8 [PubMed] Related Publications
Protein Kinase C Delta (PRKCD) has been highlighted among disrupted pathways in corticotroph adenomas. PRKCD is expressed at low level in human corticotroph adenomas and controls cell cycle in vitro. Therefore, PRKCD may play an important role in the development/progression of corticotroph adenomas, warranting further studies to understand the role of PRKCD and related pathways in restraining pituitary cell growth. We evaluated PRKCD role in influencing cell behavior in terms of cell viability, hormone expression and protein expression profile, by silencing PRKCD in AtT-20/D16v-F2 cells. PRKCD silencing increases cell viability, enhances hormone expression and induces morphological changes associated with deregulation of adhesion molecules. PRKCD silencing is associated with an increase in Epithelial Growth Factor Receptor (EGFR) expression, a marker of tumor aggressive behavior, and sensitivity to anti-EGFR molecules. PRKCD might restrain corticotroph adenoma cells from acquiring an aggressive behavior, candidating PRKCD as a possible molecular target for the treatment of corticotroph adenomas.

Panagopoulos I, Gorunova L, Bjerkehagen B, et al.
LAMTOR1-PRKCD and NUMA1-SFMBT1 fusion genes identified by RNA sequencing in aneurysmal benign fibrous histiocytoma with t(3;11)(p21;q13).
Cancer Genet. 2015; 208(11):545-51 [PubMed] Related Publications
RNA sequencing of an aneurysmal benign fibrous histiocytoma with the karyotype 46,XY,t(3;11)(p21;q13),del(6)(p23)[17]/46,XY[2] showed that the t(3;11) generated two fusion genes: LAMTOR1-PRKCD and NUMA1-SFMBT1. RT-PCR together with Sanger sequencing verified the presence of fusion transcripts from both fusion genes. In the LAMTOR1-PRKCD fusion, the part of the PRKCD gene coding for the catalytic domain of the serine/threonine kinase is under control of the LAMTOR1 promoter. In the NUMA1-SFMBT1 fusion, the part of the SFMBT1 gene coding for two of four malignant brain tumor domains and the sterile alpha motif domain is controlled by the NUMA1 promoter. The data support a neoplastic genesis of aneurysmal benign fibrous histiocytoma and indicate a pathogenetic role for LAMTOR1-PRKCD and NUMA1-SFMBT1.

Walther C, Hofvander J, Nilsson J, et al.
Gene fusion detection in formalin-fixed paraffin-embedded benign fibrous histiocytomas using fluorescence in situ hybridization and RNA sequencing.
Lab Invest. 2015; 95(9):1071-6 [PubMed] Related Publications
Benign fibrous histiocytomas (FH) can be subdivided into several morphological and clinical subgroups. Recently, gene fusions involving either one of two protein kinase C genes (PRKCB and PRKCD) or the ALK gene were described in FH. We here wanted to evaluate the frequency of PRKCB and PRKCD gene fusions in FH. Using interphase fluorescence in situ hybridization on sections from formalin-fixed paraffin-embedded (FFPE) tumors, 36 cases could be analyzed. PRKCB or PRKCD rearrangements were seen in five tumors: 1/7 regular, 0/3 aneurysmal, 0/6 cellular, 2/7 epithelioid, 0/1 atypical, 2/10 deep, and 0/2 metastatic lesions. We also evaluated the status of the ALK gene in selected cases, finding rearrangements in 3/7 epithelioid and 0/1 atypical lesions. To assess the gene fusion status of FH further, deep sequencing of RNA (RNA-Seq) was performed on FFPE tissue from eight cases with unknown gene fusion status, as well as on two FH and six soft tissue sarcomas with known gene fusions; of the latter eight positive controls, the expected fusion transcript was found in all but one, while 2/8 FH with unknown genetic status showed fusion transcripts, including a novel KIRREL/PRKCA chimera. Thus, also a third member of the PRKC family is involved in FH tumorigenesis. We conclude that gene fusions involving PRKC genes occur in several morphological (regular, cellular, aneurysmal, epithelioid) and clinical (cutaneous, deep) subsets of FH, but they seem to account for only a minority of the cases. In epithelioid lesions, however, rearrangements of PRKC or ALK were seen, as mutually exclusive events, in the majority (5/7) of cases. Finally, the study also shows that RNA-Seq is a promising tool for identifying gene fusions in FFPE tissues.

Koo KH, Jeong WJ, Cho YH, et al.
K-Ras stabilization by estrogen via PKCδ is involved in endometrial tumorigenesis.
Oncotarget. 2015; 6(25):21328-40 [PubMed] Free Access to Full Article Related Publications
Estrogens are considered as a major risk factor of endometrial cancer. In this study, we identified a mechanism of tumorigenesis in which K-Ras protein is stabilized via estrogen signaling through the ER-α36 receptor. PKCδ was shown to stabilize K-Ras specifically via estrogen signaling. Estrogens stabilize K-Ras via inhibition of polyubiquitylation-dependent proteasomal degradation. Estrogen-induced cellular transformation was abolished by either K-Ras or PKCδ knockdown. The role of PKCδ in estrogen-induced tumorigenesis was confirmed in a mouse xenograft model by reduction of tumors after treatment with rottlerin, a PKCδ inhibitor. Finally, levels of PKCδ correlated with that of Ras in human endometrial tumor tissues. Stabilization of K-Ras by estrogen signaling involving PKCδ up-regulation provides a potential therapeutic approach for treatment of endometrial cancer.

Braggio E, Van Wier S, Ojha J, et al.
Genome-Wide Analysis Uncovers Novel Recurrent Alterations in Primary Central Nervous System Lymphomas.
Clin Cancer Res. 2015; 21(17):3986-94 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Primary central nervous system lymphoma (PCNSL) is an aggressive non-Hodgkin lymphoma confined to the central nervous system. Whether there is a PCNSL-specific genomic signature and, if so, how it differs from systemic diffuse large B-cell lymphoma (DLBCL) is uncertain.
EXPERIMENTAL DESIGN: We performed a comprehensive genomic study of tumor samples from 19 immunocompetent PCNSL patients. Testing comprised array-comparative genomic hybridization and whole exome sequencing.
RESULTS: Biallelic inactivation of TOX and PRKCD was recurrently found in PCNSL but not in systemic DLBCL, suggesting a specific role in PCNSL pathogenesis. In addition, we found a high prevalence of MYD88 mutations (79%) and CDKN2A biallelic loss (60%). Several genes recurrently affected in PCNSL were common with systemic DLBCL, including loss of TNFAIP3, PRDM1, GNA13, TMEM30A, TBL1XR1, B2M, CD58, activating mutations of CD79B, CARD11, and translocations IgH-BCL6. Overall, B-cell receptor/Toll-like receptor/NF-κB pathways were altered in >90% of PNCSL, highlighting its value for targeted therapeutic approaches. Furthermore, integrated analysis showed enrichment of pathways associated with immune response, proliferation, apoptosis, and lymphocyte differentiation.
CONCLUSIONS: In summary, genome-wide analysis uncovered novel recurrent alterations, including TOX and PRKCD, helping to differentiate PCNSL from systemic DLBCL and related lymphomas.

Kološa K, Motaln H, Herold-Mende C, et al.
Paracrine effects of mesenchymal stem cells induce senescence and differentiation of glioblastoma stem-like cells.
Cell Transplant. 2015; 24(4):631-44 [PubMed] Related Publications
Glioblastoma multiforme (GBM) displays high resistance to radiation and chemotherapy, due to the presence of a fraction of GBM stem-like cells (GSLCs), which are thus representing the target for GBM elimination. Since mesenchymal stem cells (MSCs) display high tumor tropism, we examined possible antitumor effects of the secreted factors from human MSCs on four GSLC lines (NCH421k, NCH644, NIB26, and NIB50). We found that conditioned media from bone marrow and umbilical cord-derived MSCs (MSC-CM) mediated cell cycle arrest of GSLCs by downregulating cyclin D1. PCR arrays revealed significantly deregulated expression of 13 genes associated with senescence in NCH421k cells exposed to MSC-CM. Among these, ATM, CD44, COL1A1, MORC3, NOX4, CDKN1A, IGFBP5, and SERPINE1 genes were upregulated, whereas IGFBP3, CDKN2A, CITED2, FN1, and PRKCD genes were found to be downregulated. Pathway analyses in GO and KEGG revealed their association with p53 signaling, which can trigger senescence via cell cycle inhibitors p21 or p16. For both, upregulated expression was proven in all four GSLC lines exhibiting senescence after MSC-CM exposure. Moreover, MSC paracrine signals were shown to increase the sensitivity of NCH421k and NCH644 cells toward temozolomide, possibly by altering them toward more differentiated cell types, as evidenced by vimentin and GFAP upregulation, and Sox-2 and Notch-1 downregulation. Our findings support the notion that MSCs posses an intrinsic ability to inhibit cell cycle and induce senescence and differentiation of GSLCs.

Belle L, Ali N, Lonic A, et al.
The tyrosine phosphatase PTPN14 (Pez) inhibits metastasis by altering protein trafficking.
Sci Signal. 2015; 8(364):ra18 [PubMed] Related Publications
Factors secreted by tumor cells shape the local microenvironment to promote invasion and metastasis, as well as condition the premetastatic niche to enable secondary-site colonization and growth. In addition to this secretome, tumor cells have increased abundance of growth-promoting receptors at the cell surface. We found that the tyrosine phosphatase PTPN14 (also called Pez, which is mutated in various cancers) suppressed metastasis by reducing intracellular protein trafficking through the secretory pathway. Knocking down PTPN14 in tumor cells or injecting the peritoneum of mice with conditioned medium from PTPN14-deficient cell cultures promoted the growth and metastasis of breast cancer xenografts. Loss of catalytically functional PTPN14 increased the secretion of growth factors and cytokines, such as IL-8 (interleukin-8), and increased the abundance of EGFR (epidermal growth factor receptor) at the cell surface of breast cancer cells and of FLT4 (vascular endothelial growth factor receptor 3) at the cell surface of primary lymphatic endothelial cells. We identified RIN1 (Ras and Rab interactor 1) and PRKCD (protein kinase C-δ) as binding partners and substrates of PTPN14. Similar to cells overexpressing PTPN14, receptor trafficking to the cell surface was inhibited in cells that lacked PRKCD or RIN1 or expressed a nonphosphorylatable RIN1 mutant, and cytokine secretion was decreased in cells treated with PRKCD inhibitors. Invasive breast cancer tissue had decreased expression of PTPN14, and patient survival was worse when tumors had increased expression of the genes encoding RIN1 or PRKCD. Thus, PTPN14 prevents metastasis by restricting the trafficking of both soluble and membrane-bound proteins.

Mori N, Ishikawa C, Senba M
Activation of PKC-δ in HTLV-1-infected T cells.
Int J Oncol. 2015; 46(4):1609-18 [PubMed] Related Publications
Protein kinase C (PKC)-δ is a member of the PKC family. It has been implicated in tumor suppression as well as survival of various cancers. The aggressive malignancy of T lymphocytes known as adult T-cell leukemia (ATL) is associated with human T-cell leukemia virus type 1 (HTLV-1) infection. In this study, we show that HTLV-1-infected T cells are characterized by phosphorylation and nuclear translocation of PKC-δ. Expression of HTLV-1 regulatory protein Tax increased PKC-δ phosphorylation. Blockade of PKC-δ by rottlerin suppressed PKC-δ phosphorylation and inhibited cell viability in HTLV-1-infected T-cell lines and primary ATL cells. Rottlerin induced cell cycle arrest at the G1 phase and caspase-mediated apoptosis of HTLV-1-infected T cells. Rottlerin downregulated the expression of proteins involved in G1/S cell cycle transition, cyclin D2, CDK4 and 6, and c-Myc, resulting in dephosphorylation of retinoblastoma protein (pRb). Furthermore, rottlerin reduced the expression of important anti-apoptotic proteins (e.g., survivin, XIAP, Bcl-xL and c-FLIP) and Bcl-2 phosphorylation, and activated the pro-apoptotic protein Bax. Our results showed that permanent activation of nuclear factor-κB (NF-κB) by HTLV-1 Tax allows infected cells to escape cell cycle arrest and apoptosis and that PKC-δ mediates Tax-induced activation of NF-κB. Based on these findings, new therapies designed to target PKC-δ could be potentially useful in the treatment of ATL.

Baumann U, Fernández-Sáiz V, Rudelius M, et al.
Disruption of the PRKCD-FBXO25-HAX-1 axis attenuates the apoptotic response and drives lymphomagenesis.
Nat Med. 2014; 20(12):1401-9 [PubMed] Related Publications
We searched for genetic alterations in human B cell lymphoma that affect the ubiquitin-proteasome system. This approach identified FBXO25 within a minimal common region of frequent deletion in mantle cell lymphoma (MCL). FBXO25 encodes an orphan F-box protein that determines the substrate specificity of the SCF (SKP1-CUL1-F-box)(FBXO25) ubiquitin ligase complex. An unbiased screen uncovered the prosurvival protein HCLS1-associated protein X-1 (HAX-1) as the bona fide substrate of FBXO25 that is targeted after apoptotic stresses. Protein kinase Cδ (PRKCD) initiates this process by phosphorylating FBXO25 and HAX-1, thereby spatially directing nuclear FBXO25 to mitochondrial HAX-1. Our analyses in primary human MCL identify monoallelic loss of FBXO25 and stabilizing HAX1 phosphodegron mutations. Accordingly, FBXO25 re-expression in FBXO25-deleted MCL cells promotes cell death, whereas expression of the HAX-1 phosphodegron mutant inhibits apoptosis. In addition, knockdown of FBXO25 significantly accelerated lymphoma development in Eμ-Myc mice and in a human MCL xenotransplant model. Together we identify a PRKCD-dependent proapoptotic mechanism controlling HAX-1 stability, and we propose that FBXO25 functions as a haploinsufficient tumor suppressor and that HAX1 is a proto-oncogene in MCL.

Su R, Lin HS, Zhang XH, et al.
MiR-181 family: regulators of myeloid differentiation and acute myeloid leukemia as well as potential therapeutic targets.
Oncogene. 2015; 34(25):3226-39 [PubMed] Related Publications
MicroRNAs have been shown to play an important role in normal hematopoisis and leukemogenesis. Here, we report function and mechanisms of miR-181 family in myeloid differentiation and acute myeloid leukemia (AML). The aberrant overexpression of all the miR-181 family members (miR-181a/b/c/d) was detected in French-American-British M1, M2 and M3 subtypes of adult AML patients. By conducting gain- and loss-of-function experiments, we demonstrated that miR-181a inhibits granulocytic and macrophage-like differentiation of HL-60 cells and CD34+ hematopoietic stem/progenitor cells (HSPCs) by directly targeting and downregulating the expression of PRKCD (which then affected the PRKCD-P38-C/EBPα pathway), CTDSPL (which then affected the phosphorylation of retinoblastoma protein) and CAMKK1. The three genes were also demonstrated to be the targets of miR-181b, miR-181c and miR-181d, respectively. Significantly decreases in the expression levels of the target proteins were detected in AML patients. Inhibition of the expression of miR-181 family members owing to Lenti-miRZip-181a infection in bone marrow blasts of AML patients increased target protein expression levels and partially reversed myeloid differentiation blockage. In the mice implanted with AML CD34+ HSPCs, expression inhibition of the miR-181 family by Lenti-miRZip-181a injection improved myeloid differentiation, inhibited engraftment and infiltration of the leukemic CD34+ cells into the bone marrow and spleen, and released leukemic symptoms. In conclusion, our findings revealed new mechanism of miR-181 family in normal hematopoiesis and AML development, and suggested that expression inhibition of the miR-181 family could provide a new strategy for AML therapy.

Zhang QY, Li R, Zeng GF, et al.
Dihydromyricetin inhibits migration and invasion of hepatoma cells through regulation of MMP-9 expression.
World J Gastroenterol. 2014; 20(29):10082-93 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate the effects of dihydromyricetin (DHM) on the migration and invasion of human hepatic cancer cells.
METHODS: The hepatoma cell lines SK-Hep-1 and MHCC97L were used in this study. The cells were cultured in RPIM-1640 medium supplemented with 10% fetal bovine serum at 37 °C in a humidified 5% CO2 incubator. DHM was dissolved in dimethyl sulfoxide and diluted to various concentrations in medium before applying to cells. MTT assays were performed to measure the viability of the cells after DHM treatment. Wound healing and Boyden transwell assays were used to assess cancer cell motility. The invasive capacity of cancer cells was measured using Matrigel-coated transwell chambers. Matrix metalloproteinase (MMP)-2/9 activity was examined by fluorescence analysis. Western blot was carried out to analyze the expression of MMP-2, MMP-9, p-38, JNK, ERK1/2 and PKC-δ proteins. All data were analyzed by Student's t tests in GraphPad prism 5.0 software and are presented as mean ± SD.
RESULTS: DHM was found to strongly inhibit the migration of the hepatoma cell lines SK-Hep-1 (without DHM, 24 h: 120 ± 8 μmol/L vs 100 μmol/L DHM, 24 h: 65 ± 10 μmol/L, P < 0.001) and MHCC97L (without DHM, 24 h: 126 ± 7 μmol/L vs 100 μmol/L DHM, 24 h: 74 ± 6 μmol/L, P < 0.001). The invasive capacity of the cells was reduced by DHM treatment (SK-Hep-1 cells without DHM, 24 h: 67 ± 4 μmol/L vs 100 μmol/L DHM, 24 h: 9 ± 3 μmol/L, P < 0.001; MHCC97L cells without DHM, 24 h: 117 ± 8 μmol/L vs 100 μmol/L DHM, 24 h: 45 ± 2 μmol/L, P < 0.001). MMP2/9 activity was also inhibited by DHM exposure (SK-Hep-1 cells without DHM, 24 h: 600 ± 26 μmol/L vs 100 μmol/L DHM, 24 h: 100 ± 6 μmol/L, P < 0.001; MHCC97L cells without DHM, 24 h: 504 ± 32 μmol/L vs 100 μmol/L DHM 24 h: 156 ± 10 μmol/L, P < 0.001). Western blot analysis showed that DHM decreased the expression level of MMP-9 but had little effect on MMP-2. Further investigation indicated that DHM markedly reduced the phosphorylation levels of p38, ERK1/2 and JNK in a concentration-dependent manner but had no impact on the total protein levels. In addition, PKC-δ protein, a key protein in the regulation of MMP family protein expression, was up-regulated with DHM treatment.
CONCLUSION: These findings demonstrate that DHM inhibits the migration and invasion of hepatoma cells and may serve as a potential candidate agent for the prevention of HCC metastasis.

Zhao H, Bi T, Qu Z, et al.
Expression of miR-224-5p is associated with the original cisplatin resistance of ovarian papillary serous carcinoma.
Oncol Rep. 2014; 32(3):1003-12 [PubMed] Related Publications
Chemoresistance is a major challenge to successful chemotherapy of ovarian cancer, which represents the leading cause of mortality from gynecologic malignancies. We demonstrated that overexpression of miR-224-5p in ovarian cancer patients is associated with platinum-based chemoresistance using miRNA microarray analysis and quantitative real-time polymerase chain reaction (qRT-PCR) validation in vivo, as well as in 4 human ovarian cancer cell lines (C13/OV2008; A2780CP/A2780S) in vitro. In the present study, we aimed to clarify the role of miR-224-5p in regulating the chemoresistance of ovarian cancer. By using the sensitive miRNA transient transfection, we demonstrated expression and bioactivity of miR-224-5p in ovarian cancer cell lines. It is of note that enforced expression of miR-224-5p enhanced chemoresistance to cisplatin in ovarian cancer cells through apoptosis reversion. We predicted and identified the PRKCD gene as one of the targets of miR-224-5p in mediating the primary chemoresistance of ovarian cancer patients. We showed reciprocal expression of miR-224-5p and PRKCD by quantitative analysis in complete response and incomplete response patients in vivo, and 2 pairs of cisplatin resistance and sensitive cell lines in vitro, after either miR-224-5p overexpression or knockdown transfection. Additionally, miR-224-5p and PRKCD can serve as novel predictors and prognostic biomarkers for ovarian papillary serous carcinoma (OPSC) patient response to overall disease-specific survival. Our findings suggest that miR-224-5p may function as an oncogene and induce platinum resistance in OPSC at least in part by downregulating PRKCD, thereby providing a biomarker for predicting chemosensitivity to cisplatin in patients with ovarian cancer.

De Marco P, Romeo E, Vivacqua A, et al.
GPER1 is regulated by insulin in cancer cells and cancer-associated fibroblasts.
Endocr Relat Cancer. 2014; 21(5):739-53 [PubMed] Related Publications
Elevated insulin levels have been associated with an increased cancer risk as well as with aggressive and metastatic cancer phenotypes characterized by a poor prognosis. Insulin stimulates the proliferation, migration, and invasiveness of cancer cells through diverse transduction pathways, including estrogen signaling. As G protein estrogen receptor 1 (GPER1) mediates rapid cell responses to estrogens, we evaluated the potential of insulin to regulate GPER1 expression and function in leiomyosarcoma cancer cells (SKUT-1) and breast cancer-associated fibroblasts (CAFs), which were used as a model system. We found that insulin transactivates the GPER1 promoter sequence and increases the mRNA and protein expression of GPER1 through the activation of the PRKCD/MAPK1/c-Fos/AP1 transduction pathway, as ascertained by means of specific pharmacological inhibitors and gene-silencing experiments. Moreover, cell migration triggered by insulin occurred through GPER1 and its main target gene CTGF, whereas the insulin-induced expression of GPER1 boosted cell-cycle progression and the glucose uptake stimulated by estrogens. Notably, a positive correlation between insulin serum levels and GPER1 expression was found in cancer fibroblasts obtained from breast cancer patients. Altogether, our data indicate that GPER1 may be included among the complex network of transduction signaling triggered by insulin that drives cells toward cancer progression.

Noh KH, Kim SH, Kim JH, et al.
API5 confers tumoral immune escape through FGF2-dependent cell survival pathway.
Cancer Res. 2014; 74(13):3556-66 [PubMed] Free Access to Full Article Related Publications
Identifying immune escape mechanisms used by tumors may define strategies to sensitize them to immunotherapies to which they are otherwise resistant. In this study, we show that the antiapoptotic gene API5 acts as an immune escape gene in tumors by rendering them resistant to apoptosis triggered by tumor antigen-specific T cells. Its RNAi-mediated silencing in tumor cells expressing high levels of API5 restored antigen-specific immune sensitivity. Conversely, introducing API5 into API5(low) cells conferred immune resistance. Mechanistic investigations revealed that API5 mediated resistance by upregulating FGF2 signaling through a FGFR1/PKCδ/ERK effector pathway that triggered degradation of the proapoptotic molecule BIM. Blockade of FGF2, PKCδ, or ERK phenocopied the effect of API5 silencing in tumor cells expressing high levels of API5 to either murine or human antigen-specific T cells. Our results identify a novel mechanism of immune escape that can be inhibited to potentiate the efficacy of targeted active immunotherapies.

Płaszczyca A, Nilsson J, Magnusson L, et al.
Fusions involving protein kinase C and membrane-associated proteins in benign fibrous histiocytoma.
Int J Biochem Cell Biol. 2014; 53:475-81 [PubMed] Related Publications
Benign fibrous histiocytoma (BFH) is a mesenchymal tumor that most often occurs in the skin (so-called dermatofibroma), but may also appear in soft tissues (so-called deep BFH) and in the skeleton (so-called non-ossifying fibroma). The origin of BFH is unknown, and it has been questioned whether it is a true neoplasm. Chromosome banding, fluorescence in situ hybridization, single nucleotide polymorphism arrays, RNA sequencing, RT-PCR and quantitative real-time PCR were used to search for recurrent somatic mutations in a series of BFH. BFHs were found to harbor recurrent fusions of genes encoding membrane-associated proteins (podoplanin, CD63 and LAMTOR1) with genes encoding protein kinase C (PKC) isoforms PRKCB and PRKCD. PKCs are serine-threonine kinases that through their many phosphorylation targets are implicated in a variety of cellular processes, as well as tumor development. When inactive, the amino-terminal, regulatory domain of PKCs suppresses the activity of their catalytic domain. Upon activation, which requires several steps, they typically translocate to cell membranes, where they interact with different signaling pathways. The detected PDPN-PRKCB, CD63-PRKCD and LAMTOR1-PRKCD gene fusions are all predicted to result in chimeric proteins consisting of the membrane-binding part of PDPN, CD63 or LAMTOR1 and the entire catalytic domain of the PKC. This novel pathogenetic mechanism should result in constitutive kinase activity at an ectopic location. The results show that BFH indeed is a true neoplasm, and that distorted PKC activity is essential for tumorigenesis. The findings also provide means to differentiate BFH from other skin and soft tissue tumors. This article is part of a Directed Issue entitled: Rare cancers.

Chen Y, Ke G, Han D, et al.
MicroRNA-181a enhances the chemoresistance of human cervical squamous cell carcinoma to cisplatin by targeting PRKCD.
Exp Cell Res. 2014; 320(1):12-20 [PubMed] Related Publications
MicroRNAs(miRNAs) are involved in regulating the response of cancer cells to various therapeutic interventions, but their involvement in the chemoresistance of human cervical squamous cell carcinoma is not fully understood. We found miR-181a was significantly up-regulated in specimens from patients with chemoresistant cervical squamous cell carcinoma. In this study, we aimed to clarify the role of miR-181a in regulating the chemoresistance of cervical cancer. Two human cervical squamous cancer cell lines, SiHa and Me180, were used. Enforced expression of miR-181a enhanced chemoresistance to cisplatin in cervical cancer cells through apoptosis reversion. In a nude mouse xenograft model, the overexpression of miR-181a markedly inhibited the therapeutic response to cisplatin. PRKCD, a target gene of miR-181a and a promoter of apoptosis, was negatively regulated by miR-181a. We found that the effect of miR-181a on chemoresistance was mediated by PRKCD. Additionally, silencing of PRKCD yielded an effect similar to that of miR-181a up-regulation and inhibited apoptosis in cervical cancer cells. Our findings suggest that miR-181a may function as an oncogene and induce chemoresistance in cervical squamous cell carcinoma cells at least in part by down-regulating PRKCD, thus may provide a biomarker for predicting chemosensitivity to cisplatin in patients with cervical squamous cancer.

Gentilin E, Tagliati F, Filieri C, et al.
miR-26a plays an important role in cell cycle regulation in ACTH-secreting pituitary adenomas by modulating protein kinase Cδ.
Endocrinology. 2013; 154(5):1690-700 [PubMed] Free Access to Full Article Related Publications
The functional aftermath of microRNA (miRNA) dysregulation in ACTH-secreting pituitary adenomas has not been demonstrated. miRNAs represent diagnostic and prognostic biomarkers as well as putative therapeutic targets; their investigation may shed light on the mechanisms that underpin pituitary adenoma development and progression. Drugs interacting with such pathways may help in achieving disease control also in the settings of ACTH-secreting pituitary adenomas. We investigated the expression of 10 miRNAs among those that were found as most dysregulated in human pituitary adenoma tissues in the settings of a murine ACTH-secreting pituitary adenoma cell line, AtT20/D16v-F2. The selected miRNAs to be submitted to further investigation in AtT20/D16v-F2 cells represent an expression panel including 5 up-regulated and 5 down-regulated miRNAs. Among these, we selected the most dysregulated mouse miRNA and searched for miRNA targets and their biological function. We found that AtT20/D16v-F2 cells have a specific miRNA expression profile and that miR-26a is the most dysregulated miRNA. The latter is overexpressed in human pituitary adenomas and can control viable cell number in the in vitro model without involving caspase 3/7-mediated apoptosis. We demonstrated that protein kinase Cδ (PRKCD) is a direct target of miR-26a and that miR26a inhibition delays the cell cycle in G1 phase. This effect involves down-regulation of cyclin E and cyclin A expression via PRKCD modulation. miR-26a and related pathways, such as PRKCD, play an important role in cell cycle control of ACTH pituitary cells, opening new therapeutic possibilities for the treatment of persistent/recurrent Cushing's disease.

Hernández-Maqueda JG, Luna-Ulloa LB, Santoyo-Ramos P, et al.
Protein kinase C delta negatively modulates canonical Wnt pathway and cell proliferation in colon tumor cell lines.
PLoS One. 2013; 8(3):e58540 [PubMed] Free Access to Full Article Related Publications
The tumor suppressor Adenomatous Polyposis coli (APC) gene is mutated or lost in most colon cancers. Alterations in Protein kinase C (PKC) isozyme expression and aberrant regulation also comprise early events in intestinal carcinomas. Here we show that PKCδ expression levels are decreased in colon tumor cell lines with respect to non-malignant cells. Reciprocal co-immunoprecipitation and immunofluorescence studies revealed that PKCδ interacts specifically with both full-length (from non-malignant cells) and truncated APC protein (from cancerous cells) at the cytoplasm and at the cell nucleus. Selective inhibition of PKCδ in cancer SW480 cells, which do not possess a functional β-catenin destruction complex, did not affect β-catenin-mediated transcriptional activity. However, in human colon carcinoma RKO cells, which have a normal β-catenin destruction complex, negatively affected β-catenin-mediated transcriptional activity, cell proliferation, and the expression of Wnt target genes C-MYC and CYCLIN D1. These negative effects were confirmed by siRNA-mediated knockdown of PKCδ and by the expression of a dominant negative form of PKCδ in RKO cells. Remarkably, the PKCδ stably depleted cells exhibited augmented tumorigenic activity in grafted mice. We show that PKCδ functions in a mechanism that involves regulation of β-catenin degradation, because PKCδ inhibition induces β-catenin stabilization at the cytoplasm and its nuclear presence at the C-MYC enhancer even without Wnt3a stimulation. In addition, expression of a dominant form of PKCδ diminished APC phosphorylation in intact cells, suggesting that PKCδ may modulate canonical Wnt activation negatively through APC phosphorylation.

Arany S, Benoit DS, Dewhurst S, Ovitt CE
Nanoparticle-mediated gene silencing confers radioprotection to salivary glands in vivo.
Mol Ther. 2013; 21(6):1182-94 [PubMed] Free Access to Full Article Related Publications
Radiation treatment of head and neck cancers causes irreversible damage of the salivary glands (SG). Here, we introduce a preclinical mouse model for small-interfering RNA (siRNA)-based gene silencing to provide protection of SG from radiation-induced apoptosis. Novel, pH-responsive nanoparticles complexed with siRNAs were introduced into mouse submandibular glands (SMG) by retroductal injection to modulate gene expression in vivo. To validate this approach, we first targeted Nkcc1, an ion transporter that is essential for saliva secretion. Nkcc1 siRNA delivery resulted in efficient knockdown, as quantified at the mRNA and the protein levels, and the functional result of Nkcc1 knockdown phenocopied the severe decrease in saliva secretion, characteristic of the systemic Nkcc1 gene knockout. To establish a strategy to prevent apoptotic cell loss due to radiation damage, siRNAs targeting the proapoptotic Pkcδ gene were administered into SMG before ionizing radiation. Knockdown of Pkcδ not only reduced the number of apoptotic cells during the acute phase of radiation damage, but also markedly improved saliva secretion at 3 months in irradiated animals, indicating that this treatment confers protection from hyposalivation. These results demonstrate that nanoparticle delivery of siRNAs targeting a proapoptotic gene is a localized, nonviral, and effective means of conferring radioprotection to the SGs.

Ke G, Liang L, Yang JM, et al.
MiR-181a confers resistance of cervical cancer to radiation therapy through targeting the pro-apoptotic PRKCD gene.
Oncogene. 2013; 32(25):3019-27 [PubMed] Related Publications
The purpose of this study was to define the roles of miR-181a in determining sensitivity of cervical cancer to radiation therapy, to explore the underlying mechanism and to evaluate the potential of miR-181a as a biomarker for predicting radio-sensitivity. Tumor specimens from 18 patients with a histological diagnosis of squamous cervical carcinoma (stage IIIB) were used in the micro-RNA profiling and comparison. These patients never received any chemotherapy before radiation therapy. Human cervical cancer cell lines, SiHa and Me180, were used in vitro (cell culture) and in vivo (animal) studies. Transfection of tumor cells with the mimic or inhibitor of miR-181a, and reporter gene assay, were performed to investigate the role of miR-181a in determining radio-sensitivity and the target gene. Higher expression of miR-181a was observed in human cervical cancer specimens and cell lines that were insensitive to radiation therapy, as compared with sensitive cancer specimens and the cell lines. We also found that miR-181a negatively regulated the expression of PRKCD, a pro-apoptotic protein kinase, via targeting its 3'-untranslated region (UTR), thereby inhibiting irradiation-induced apoptosis and decreasing G2/M block. The role of miR-181a in conferring cellular resistance to radiation treatment was validated both in cell culture models and in mouse tumor xenograft models. The effect of miR-181a on radio-resistance was mediated through targeting the 3'-UTR of PRKCD gene. Thus, the expression level of miR-181a in cervical cancer may serve as a biomarker for sensitivity to radiation therapy, and targeting miR-181a may represent a new approach to sensitizing cervical cancer to radiation treatment.

Zuo Y, Wu Y, Chakraborty C
Cdc42 negatively regulates intrinsic migration of highly aggressive breast cancer cells.
J Cell Physiol. 2012; 227(4):1399-407 [PubMed] Related Publications
The small GTPase Cdc42 has been implicated as an important regulator of cell migration. However, whether Cdc42 plays similar role in all cancer cells irrespective of metastatic potential remains poorly defined. Here, we show by using three different breast cancer cell lines with different metastatic potential, the role of Cdc42 in cell migration/invasion and its relationship with a number of downstream signaling pathways controlling cell migration. Small interfering RNA (siRNA)-mediated knockdown of Cdc42 in two highly metastatic breast cancer cell lines (MDA-MB-231 and C3L5) resulted in enhancement, whereas the same in moderately metastatic (Hs578T) cell line resulted in inhibition of intrinsic cellular migration/invasion. Furthermore, Cdc42 silencing in MDA-MB-231 and C3L5 but not Hs578T cells was shown to be accompanied by increased RhoA activity and phosphorylation of protein kinase C (PKC)-δ, extracellular signal regulated kinase1/2 (Erk1/2), and protein kinase A (PKA). Pharmacological inhibition of PKCδ, MEK-Erk1/2, or PKA was shown to inhibit migration of both control and Cdc42-silenced MDA-MB-231 cells. Furthermore, introduction of constitutively active Cdc42 was shown to decrease migration/invasion of MDA-MB-231 and C3L5 but increase migration/invasion of Hs578T cells. This decreased migration/invasion of MDA-MB-231 and C3L5 cells was also shown to be accompanied by the decrease in the phosphorylations of PKCδ, Erk1/2, and PKA. These results suggested that endogenous Cdc42 could exert a negative regulatory influence on intrinsic migration/invasion and some potentially relevant changes in phosphorylation of PKCδ, Erk1/2, and PKA of some aggressive breast cancer cells.

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