Research IndicatorsGraph generated 01 September 2019 using data from PubMed using criteria.
Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic. 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).
OMIM, Johns Hopkin University
Referenced article focusing on the relationship between phenotype and genotype.
International Cancer Genome Consortium.
Summary of gene and mutations by cancer type from ICGC
Cancer Genome Anatomy Project, NCI
COSMIC, Sanger Institute
Somatic mutation information and related details
GEO Profiles, NCBI
Search the gene expression profiles from curated DataSets in the Gene Expression Omnibus (GEO) repository.
Latest Publications: RACK1 (cancer-related)
Yoshino Y, Qi H, Kanazawa R, et al.RACK1 regulates centriole duplication by controlling localization of BRCA1 to the centrosome in mammary tissue-derived cells.
Oncogene. 2019; 38(16):3077-3092 [PubMed
] Related Publications
Breast cancer gene 1 (BRCA1) is a tumor suppressor that is associated with hereditary breast and ovarian cancer. BRCA1 functions in DNA repair and centrosome regulation together with BRCA1-associated RING domain protein (BARD1), a heterodimer partner of BRCA1. Obg-like ATPase 1 (OLA1) was identified as a protein that interacts with BARD1. OLA1 regulates the centrosome by binding to and collaborating with BRCA1 and BARD1. We identified receptor for activated C kinase (RACK1) as a protein that interacts with OLA1. RACK1 directly bound to OLA1, the N-terminal region of BRCA1, and γ-tubulin, associated with BARD1, and localized the centrosomes throughout the cell cycle. Knockdown of RACK1 caused abnormal centrosomal localization of BRCA1 and abrogated centriole duplication. Overexpression of RACK1 increased the centrosomal localization of BRCA1 and caused centrosome amplification due to centriole overduplication. The number of centrioles in cells with two γ-tubulin spots was higher in cell lines derived from mammary tissue compared to those derived from other tissues. The effects of aberrant RACK1 expression level on centriole duplication were observed in cell lines derived from mammary tissue, but not in those derived from other tissues. Two BRCA1 variants, R133H and E143K, and a RACK1 variant, K280E, associated with cancer, which weakened the BRCA1-RACK1 interaction, interfered with the centrosomal localization of BRCA1 and reduced centrosome amplification induced by overexpression of RACK1. These results suggest that RACK1 regulates centriole duplication by controlling the centrosomal localization of BRCA1 in mammary tissue-derived cells and that this is dependent on the BRCA1-RACK1 interaction.
Zhang L, Xu Y, Wang L, Liu HRole of RACK1 on cell proliferation, adhesion, and bortezomib-induced apoptosis in multiple myeloma.
Int J Biol Macromol. 2019; 121:1077-1085 [PubMed
] Related Publications
Receptor for activated C kinase 1 (RACK1), a scaffold protein, plays a crucial role in the progression of various cancers. However, the biological function and underlying mechanism of RACK1 in multiple myeloma (MM) cells remain unclear. The present study aimed to explore the function of RACK1 on the cell proliferation, adhesion, and bortezomib-induced apoptosis in MM. We found that RACK1 was significantly overexpressed in myeloma cell lines and primary myeloma cells compared with normal bone marrow plasma cells. Moreover, immunofluorescence revealed that RACK1 was primarily expressed in the cytoplasm of MM cells. Knockdown of RACK1 impaired growth of MM cells, blocked entry into the S-phase of the cell cycle, and resulted in reduced cell adhesion rates. More importantly, knockdown of RACK1 decreased the proliferation of MM cells by activating P-P38 and P-ERK in the MAPK/ERK signaling pathway. We also found that altered expression of RACK1 is associated with bortezomib-mediated MM cell apoptosis. In summary, these results may provide a possible target for therapy in MM.
Boratkó A, Csortos CTIMAP, the versatile protein phosphatase 1 regulator in endothelial cells.
IUBMB Life. 2017; 69(12):918-928 [PubMed
] Related Publications
Transforming growth factor (TGF)-β inhibited membrane associated protein, TIMAP, is the member of the myosin phosphatase targeting protein (MYPT) family of protein phosphatase 1 (PP1) regulatory subunits. The N-terminal part of TIMAP has a typical MYPT family structure with a sequence element called MyPhone (myosin phosphatase N-terminal element), a putative bipartite nuclear localization signal, a PP1 catalytic subunit binding motif, and five ankyrin repeats. The C-terminal half of TIMAP is intrinsically disordered, but ends with a functional CAAX box for lipid modification which allows localization of TIMAP at the plasma membrane. TIMAP is prenylated by farnesyl transferase with the contribution of the anchoring protein, RACK1 in the cytoplasm. The controlling effect of TIMAP on PP1 is moderated by PKA/GSK3β and PKC mediated phosphorylation of TIMAP, the sites are located in the disordered region of the protein. TIMAP is abundant in endothelial cells. A growing body of evidence attained through characterization of newly identified protein partners calls attention to its critical role in normal and pathological activities of the endothelium via regulation of PP1. TIMAP binds the non-integrin laminin receptor 1 and the endothelin converting enzyme 1, which may connect TIMAP to angiogenesis, tumor invasion and metastasis. Barrier protecting role of TIMAP was shown for pulmonary artery endothelial cells. ERM (ezrin-radixin-moesin) proteins, as potential in vivo PP1-TIMAP substrates, are critical targets in the barrier maintenance. TIMAP affects phosphorylation level and subcellular localization of merlin and eukaryotic elongation factor-1A1. Merlin is a key component of signaling pathways regulating cell proliferation, membrane domain formation and cell-cell junction organization. Noncanonical functions of the elongation factor include a role in organization of cytoskeleton dynamics and in apoptosis. The interacting/binding partners identified so far demonstrate a rather complex role of TIMAP in key functions of the endothelium offering TIMAP as a plausible target in pathological issues. © 2017 IUBMB Life, 69(12):918-928, 2017.
Cervical cancer is one of the most common malignant tumors in women all over the world. However, the exact etiology of cervical cancer remains unclear. The receptor for activated protein kinase C (RACK1) is reported to be involved in tumorigenesis and tumor progression. Besides, the prognostic value of RACK1 in several kinds of tumors has been identified. However, there are limited studies on the functional role of RACK1 in cervical cancer. In this study, we tested the expression level of RACK1 by immunohistochemistry and western blot technologies and find that it is upregulated in cervical cancer. Colony formation and CCK8 assays indicate that RACK1 promotes cell proliferation in CaSki cervical cancer cells. While the silence of RACK1 decreases the cell proliferation in CCK8 analysis. β-galactosidase staining suggests that RACK1 decreases cell senescence in cervical cancer cells. Invasion and migration assay show that RACK1 promotes the invasion and migration of cervical cancer cells. Also, when RACK1 was silenced, it exerts the opposite result. Furthermore, the mRNA expression levels of MMP‑3, MMP‑9 and MMP‑10 were upregulated in RACK1‑overexpressed CaSki cells by qPCR analysis. RACK1 also induces S phase accumulation in cell cycle analysis and suppresses cell apoptosis in cervical cancer cells. Flow cytometry analysis of mitochondria functions suggests that RACK1 increases the mitochondrial membrane potential (Δψm) levels to prevent mitochondrial apoptosis in cervical cancer cells. To explore the possible mechanism of RACK1, we tested and found that RACK1 upregulates the expression of NF-κB, cyclin D1 and CDK4 and downregulates the expression of p53, p38, p21 and STAT1 in cervical cancer cells. These results suggest that RACK1 promotes cell growth and invasion and inhibits the senescence and apoptosis in cervical cancer cells probably by affecting the p53 pathway.
Wang L, Xue GBCatalpol suppresses osteosarcoma cell proliferation through blocking epithelial-mesenchymal transition (EMT) and inducing apoptosis.
Biochem Biophys Res Commun. 2018; 495(1):27-34 [PubMed
] Related Publications
Catalpol, an iridoid glucoside compound, is reported to possess diverse pharmacological actions. However, its effects on osteosarcoma are little to be known. In the present study, we showed that catalpol could strongly suppress osteosarcoma progression. Catalpol dose-dependently reduced the cancer cell viability. The migration of osteosarcoma cells was also consistently suppressed by catalpol treatment using the wound healing and transwell migration analysis. Catalpol reduced the expressions of Kras, receptor for activated C-kinase 1(RACK1) and matrix metalloproteinase (MMP)-2 in a dose-dependent manner, revealing the blockage of migration. Moreover, both intrinsic and extrinsic apoptosis were triggered by catalpol, as evidenced by improved cleaved Caspase-8/-9/-3 and Poly-(ADP-ribose) polymerase (PARP). Release of Cyto-c in cytoplasm and Bax up-regulation in total cells were observed in catalpol-treated cells, while mitochondrial Cyto-c and cellular Bcl-2 were down-regulated by catalpol. Reactive oxygen species (ROS) production was also involved in catalpol-induced cell death. Further, ROS scavenger, N-acetylcysteine (NAC), impeded catalpol-caused apoptosis. And suppression of signal transducer and activator of transcription 3/Janus kinase 2 gene/Src (STAT3/JAK2/Src) was involved in catalpol-induced cell death. In vivo, catalpol showed effective ability to reduce the tumor growth. Our results illustrated that catalpol might be considered as a promising pharmacological agent to suppress osteosarcoma.
Wang S, Shen M, Wen X, et al.Correlation of the expressions of IGF1R-RACK1-STAT3 and Bcl-xl in nasopharyngeal carcinoma with the clinicopathological features and prognosis of nasopharyngeal carcinoma.
J Cell Biochem. 2018; 119(2):1931-1941 [PubMed
] Related Publications
The aim of this study was to investigate the correlation of expression of IGF1R-RACK1-STAT3 and Bcl-xl in nasopharyngeal carcinoma (NPC) with the clinicopathological features and the prognosis of NPC. Our study selected 215 NPC tissues and 178 chronic nasopharyngitis tissues (control group). Positive expression rates of IGF1R, RACK1, STAT3, and Bcl-xl were tested by immunohistochemical method, and expression of IGF1R, RACK1, STAT3, Bcl-xl, Bcl-2, and Bax by western blotting. Correlation of IGF1R, RACK1, STAT3, and Bcl-xl with the clinicopathological features of NPC was analyzed. The correlation among those four expression was analyzed by Spearman. The survival of NPC and independent factors of prognosis were tested by Kaplan-Meier and COX proportional hazards model respectively. The NPC group had higher positive expression rates of IGF1R, RACK1, STAT3, and Bcl-xl, and elevated expression of IGF1R, RACK1, STAT3, Bcl-xl, Bcl-2, and Bax. The lymph node metastasis (LNM) group had higher positive expression rates of IGF1R and RACK1 when compared with the non-LNM group. Patients with stage III and IV had higher positive expression rates of IGF1R, RACK1, STAT3, and Bcl-xl. There was positive correlation between expression of IGF1R and RACK1, STAT3. Such correlation was found between RACK1 and STAT3. Patients with negative expression of IGF1R, RACK1, STAT3, and Bcl-xl had higher survival rates. The risky factors of poor prognosis of NPC were positive expression of IGF1R, RACK1, STAT3 and Bcl-xl, and LNM. IGF1R-RACK1-STAT3 and Bcl-xl expression correlated with the clinicopathological features and poor prognosis of NPC.
Liu B, Wang C, Chen P, et al.RACK1 promotes radiation resistance in esophageal cancer via regulating AKT pathway and Bcl-2 expression.
Biochem Biophys Res Commun. 2017; 491(3):622-628 [PubMed
] Related Publications
RACK1 is a seven Trp-Asp 40 repeat protein, which interacts with a wide range of kinases and proteins. RACK1 plays an important role in the proliferation and progression of various cancers. The aim of this study is to detect the role of RACK1 in the radioresistance in esophageal cancer. The results indicated that downregulation of RACK1 reduced the colony formation ability, proliferation ability and resistance of cells to radiation effection through regulating the radiation-related proteins including pAKT, Bcl-2 and Bim; whereas upregulation of RACK1 promoted the ability and radioresistance of ESCC cells. Our findings suggest that RACK1 promotes proliferation and radioresistance in ESCC cells by activating the AKT pathway, upregulating Bcl-2 expression and downregulating protein levels of Bim. Our study fills in gaps in the field of RACK1 and radiation resistance and may provide new possibilities for improving strategies of radiotherapy in esophageal cancer.
Zou YH, Li XD, Zhang QH, Liu DZRACK1 Silencing Induces Cell Apoptosis and Inhibits Cell Proliferation in Hepatocellular Carcinoma MHCC97-H Cells.
Pathol Oncol Res. 2018; 24(1):101-107 [PubMed
] Related Publications
This study aimed to explore the effects of RACK1 gene silencing on the apoptosis and proliferation of hepatocellular carcinoma (HCC) MHCC97-H cells. After transfecting MHCC97-H cells with siRNA, RACK1 gene silencing model was established. The cells were divided into blank group, siRNA group and empty plasmid group, respectively. The mRNA and protein expressions of RACK1, cyclin D1 and BAX were determined by qRT-PCR and Western blotting. CCK-8 assay, flow cytometry and FITC-Annexin V/PI staining were used to determine cell viability, cell cycle and cell apoptosis, respectively. The results of qRT-PCR and Western blotting suggested that when compared with the blank group and the empty plasmid group, the mRNA and protein expressions of RACK1 and Cyclin D1 decreased significantly while the mRNA and protein BAX expressions increased substantially in the siRNA group (all P < 0.05). The results of CCK-8 assay revealed that the siRNA group exhibited significantly lower cell viability when compared with the blank group and the empty plasmid group (both P < 0.05); and the cell viability in the siRNA group decreased gradually with the increase of time. The results of flow cytometry and FITC-Annexin V/PI staining indicated that when compared with the blank group and the empty plasmid group, the proportion of cells in S phase was markedly lower and the apoptosis rate was significantly higher in the siRNA group (both P < 0.05). Our study suggests that inhibition of RACK1 could suppress cell proliferation and induce apoptosis in HCC MHCC97-H cells.
Buoso E, Galasso M, Serafini MM, et al.Transcriptional regulation of RACK1 and modulation of its expression: Role of steroid hormones and significance in health and aging.
Cell Signal. 2017; 35:264-271 [PubMed
] Related Publications
The Receptor for Activated C Kinase 1 (RACK1) is a scaffold protein for different kinases and membrane receptors. RACK1 can shuttle proteins to their sites of action, facilitate cross-talk among distinct signaling pathways or recruit other signaling proteins into the complexes. Therefore, it is a key mediator of various pathways and is involved in various biological events including development, immune response, brain activity and cancer. Because of its importance, it is of extreme significance to understand the transcriptional mechanisms governing its expression. The identification of regulatory elements in the promoter of RACK1 shed some light on its transcriptional modulation in physiological and pathological context. Literature data support the existence of a complex hormonal balance, between glucocorticoids and androgens, in the control of RACK1 expression due to specific and complex interactions on the RACK1 promoter. These and other informations suggest that a better understanding of RACK1 transcriptional regulation is essential to unravel its role. Furthermore, the modulation of its expression in physiological or pathological conditions may be of interest in different context, such as aging and cancer.
TDP-43 is a well known RNA binding protein involved in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Lobar Dementia (FTLD). In physiological conditions, TDP-43 mainly localizes in the nucleus and shuttles, at least in neurons, to the cytoplasm to form TDP-43 RNA granules. In the nucleus, TDP-43 participates to the expression and splicing of RNAs, while in the cytoplasm its functions range from transport to translation of specific mRNAs. However, if loss or gain of these TDP-43 functions are affected in ALS/FTLD pathogenesis is not clear. Here, we report that TDP-43 localizes on ribosomes not only in primary neurons but also in SH-SY5Y human neuroblastoma cells. We find that binding of TDP-43 to the translational machinery is mediated by an interaction with a specific ribosomal protein, RACK1, and that an increase in cytoplasmic TDP-43 represses global protein synthesis, an effect which is rescued by overexpression of RACK1. Ribosomal loss of RACK1, which excludes TDP-43 from the translational machinery, remarkably reduces formation of TDP-43 cytoplasmic inclusions in neuroblastoma cells. Finally, we corroborate the interaction between TDP-43 and RACK1 on polyribosomes of neuroblastoma cells with mis-localization of RACK1 on TDP-43 positive cytoplasmic inclusions in motor neurons of ALS patients. In conclusions, results from this study suggest that TDP-43 represents a translational repressor not only for specific mRNAs but for overall translation and that its binding to polyribosomes through RACK1 may promote, under conditions inducing ALS pathogenesis, the formation of cytoplasmic inclusions.
Prostate-Tumor-Overexpressed-1 (PTOV1) is a conserved adaptor protein discovered as overexpressed in prostate cancer. Since its discovery, the number of binding partners and associated cellular functions has increased and helped to identify PTOV1 as regulator of gene expression at transcription and translation levels. Its overexpression is associated with increased tumor grade and proliferation in prostate cancer and other neoplasms, including breast, ovarian, nasopharyngeal, squamous laryngeal, hepatocellular and urothelial carcinomas. An important contribution to higher levels of PTOV1 in prostate tumors is given by the frequent rate of gene amplifications, also found in other tumor types. The recent resolution of the structure by NMR of the PTOV domain in PTOV2, also identified as Arc92/ACID1/MED25, has helped to shed light on the functions of PTOV1 as a transcription factor. In parallel, by studying its interaction with RACK1, we have discovered PTOV1 action in promoting mRNAs translation. Here, we will focus on the role of PTOV1 in cancer, re-examine its pro-oncogenic effects and re-evaluate the most relevant interactions and evidences of its cellular functions. The data are used to formulate a model for the mechanisms of action of PTOV1 in line with its recently described activities and cellular pathways modulated in cancer.
Chemoresistant mechanisms in T-cell acute lymphoblastic leukemia (T-ALL) patients are not clarified. The apoptotic signaling mediated by receptor of activated C kinase 1 (Rack1), protein kinase C (PKC) and FEM1 homolog b (FEM1b) was investigated in two T-ALL-derived cell lines (Jurkat and CCRF-CEM) following treatment with chemotherapy drugs vincristine and prednisone. Serum starvation or chemotherapeutic drugs significantly reduced Rack1 level and PKC activation, while promoted cellular apoptosis in both cell lines. Rack1 overexpression protected T-ALL cell against starvation or chemotherapeutic drug-induced apoptosis. Moreover, Rack1 overexpression reduced the level of cytochrome c and active caspase 3 as well as FEM1b and apoptotic protease activating factor-1 (Apaf-1), and inhibited induction of cellular apoptosis in chemotherapeutic drug-treated Jurkat cell. Interaction of Rack1 and PKCα, not PKCβ, was detected in both cell lines. Of note, Rack1 overexpression abrogated reduction of PKC kinase activity in chemotherapeutic drug-treated T-ALL cell. PKC kinase inhibitor Go6976 or siPKCα inhibited downregulation of FEM1b and/or Apaf-1, and thus increased cellular apoptosis in Rack1-overexpressed T-ALL cell receiving chemotherapeutic drugs. Accordingly, our data provided evidence that increased Rack1-mediated upregulation of PKC kinase activity may be responsible for the development of chemoresistance in T-ALL-derived cell line potentially by reducing FEM1b and Apaf-1 level.
Cheng S, Ren J, Su L, et al.O-GlcNAcylation of the Signaling Scaffold Protein, GNB2L1 Promotes its Degradation and Increases Metastasis of Gastric Tumours.
Biochem Biophys Res Commun. 2016; 478(4):1497-502 [PubMed
] Related Publications
GNB2L1 is an intercellular scaffold protein of the Trp-Asp (WD) repeat protein family, and has been reported to play suppressive roles in the progression of gastric cancer. However, the regulatory mechanisms of GNB2L1 in gastric cancer still remain largely elusive. In the present study, we found that OGT was capable to interact with GNB2L1 directly and modify GNB2L1 with O-GlcNAcylation in gastric cancer, and this O-GlcNAcylation hindered the inhibition of GNB2L1 on migration of gastric cancer cells. Moreover, O-GlcNAcylation regulated the degradation instead of the synthesis of GNB2L1 in gastric cancer, and our data suggested the O-GlcNAcylation on GNB2L1 influenced its stability directly. In addition, the clinical data revealed the negative correlation of the protein level instead of the mRNA level of GNB2L1 with OGT expression, and showed that OGT reversed the inhibition of GNB2L1 on metastasis, and worsened the prognosis of GNB2L1(High) patients. In summary, this study indicated the O-GlcNAcylation on GNB2L1 reversed its inhibition on gastric tumour metastasis via promoting its degradation.
Li X, Xiao Y, Fan S, et al.RACK1 overexpression associates with pancreatic ductal adenocarcinoma growth and poor prognosis.
Exp Mol Pathol. 2016; 101(2):176-186 [PubMed
] Related Publications
OBJECTIVES: The receptor for activated protein kinase C (RACK1) is a scaffold protein involved in multiple intracellular signal pathways. Previous studies have shown that RACK1 is associated with the progression of multiple cancer types, including hepatocellular carcinoma and gastric cancer. However, the role of RACK1 in human pancreatic ductal adenocarcinoma (PDAC) remains unclear.
METHODS: In this study, the expression of RACK1 was evaluated by Western blot analysis in 8 paired fresh PDAC tissues and immunohistochemistry on 179 paraffin-embedded slices. Then, we used Fisher exact test to analyze the correlation between RACK1 expression and clinicopathological characteristics. Starvation and re-feeding assay was used to assess cell cycle. Western blot, CCK8, flow cytometry assays, and colony formation analyses demonstrated that RACK1 played an essential role in PDAC development. Annexin-V/PI apoptotic assay and western blot showed that RACK1 was involved in regulating the apoptosis of PDAC cells.
RESULTS: RACK1 was highly expressed in PDAC tissues and cell lines and was significantly associated with multiple clinicopathological factors. Univariate and multivariate analyses showed that high RACK1 expression was identified to be an independent prognostic factor for PDAC patients' survival. In vitro, serum starvation-refeeding experiment suggested that RACK1 was upregulated in proliferating PDAC cells, together with the percentage of cells at the S phase, and was correlated with the expression of Cyclin D1. Moreover, Overexpression of RACK1 facilitated the proliferation and cell cycle progression of PDAC cells, while downregulation of RACK1 induced growth impairment, G1/S cell cycle arrest and apoptosis in PDAC cells. Silencing RACK1 decreased bcl-2 expression, increased cleaved caspase3 expression level and induced the apoptosis of PDAC cells.
CONCLUSIONS: Our results suggest that RACK1 could play an important role in the tumorigenesis of PDAC and serve as a potential therapeutical target in PDAC treatment.
Zhang X, Liu N, Ma D, et al.Receptor for activated C kinase 1 (RACK1) promotes the progression of OSCC via the AKT/mTOR pathway.
Int J Oncol. 2016; 49(2):539-48 [PubMed
] Related Publications
Our previous study suggested that receptor for activated C kinase 1 (RACK1) contribute to the progression of oral squamous cell carcinoma (OSCC). The aim of this study is to elucidate the mechanism by which RACK1 regulates cell growth in OSCC using in vitro and in vivo models. The effects of RACK1 knockdown with lentivirus based shRNA in stable cell lines were evaluated by Q-PCR and western blot analysis. RACK1 silencing effects on the cell cycle in OSCC cells were detected by flow cytometry and western blot analysis. The effect of RACK1 silencing on inhibiting the progression of OSCC was illustrated using a xenografted mouse model. RACK1 and relevant signaling pathways were investigated in tissues and cells using immunohistochemistry and/or western blot analysis. Stable silencing of the RACK1 gene resulted in a distinct G1 and G2 phase arrest by downregulating Cyclin B1 and Cyclin D1. Depleted RACK1 led to markedly decreased tumor volume and the expression of Ki67, CD34, and VEGF in vivo. The expression of RACK1 and p-AKT has a parallel pattern in different stages of oral carcinogenesis tissues. In addition, the protein level of RACK1 was positively correlated with p-AKT in OSCC tissue samples and cell lines. We found specific transient knockdown of RACK1 could downregulate the protein levels of p-AKT, p-mTOR, and p-S6 in a dose-dependent manner. This study demonstrates that RACK1-dependent OSCC growth and survival may be related to the increased activation of the AKT/mTOR/S6 pathway.
Hypoxia is an adverse factor in cervical cancer, and hypoxia-related gene expression could be a powerful biomarker for identifying the aggressive hypoxic tumors. Reverse transcription quantitative PCR (RT-qPCR) is a valuable method for gene expression studies, but suitable reference genes for data normalization that are independent of hypoxia status and clinical parameters of cervical tumors are lacking. In the present work, we aimed to identify reference genes for RT-qPCR studies of hypoxia in squamous cervical cancer. From 422 candidate reference genes selected from the literature, we used Illumina array-based expression profiles to identify 182 genes not affected by hypoxia in cervical cancer, i.e. genes regulated by hypoxia in eight cervical cancer cell lines or correlating with the hypoxia-associated dynamic contrast-enhanced magnetic resonance imaging parameter ABrix in 42 patients, were excluded. Among the 182 genes, nine candidates (CHCHD1, GNB2L1, IPO8, LASP1, RPL27A, RPS12, SOD1, SRSF9, TMBIM6) that were not associated with tumor volume, stage, lymph node involvement or disease progression in array data of 150 patients, were selected for further testing by RT-qPCR. geNorm and NormFinder analyses of RT-qPCR data of 74 patients identified CHCHD1, SRSF9 and TMBIM6 as the optimal set of reference genes, with stable expression both overall and across patient subgroups with different hypoxia status (ABrix) and clinical parameters. The suitability of the three reference genes were validated in studies of the hypoxia-induced genes DDIT3, ERO1A, and STC2. After normalization, the RT-qPCR data of these genes showed a significant correlation with Illumina expression (P<0.001, n = 74) and ABrix (P<0.05, n = 32), and the STC2 data were associated with clinical outcome, in accordance with the Illumina data. Thus, CHCHD1, SRSF9 and TMBIM6 seem to be suitable reference genes for studying hypoxia-related gene expression in squamous cervical cancer samples by RT-qPCR. Moreover, STC2 is a promising prognostic hypoxia biomarker in cervical cancer.
The contribution of long noncoding RNAs (lncRNAs) to metastasis of gastric cancer remains largely unknown. We used microarray analysis to identify lncRNAs differentially expressed between normal gastric tissues and gastric cancer tissues and validated these differences in quantitative real-time (qRT)-PCR experiments. The expression levels of lncRNA olfactory receptor, family 3, subfamily A, member 4 (OR3A4) were significantly associated with lymphatic metastasis, the depth of cancer invasion, and distal metastasis in 130 paired gastric cancer tissues. The effects of OR3A4 were assessed by overexpressing and silencing OR3A4 in gastric cancer cells. OR3A4 promoted cancer cell growth, angiogenesis, metastasis, and tumorigenesis in vitro and in vivo. Global microarray analysis combined with RT-PCR, RNA immunoprecipitation, and RNA pull-down analyses after OR3A4 transfection demonstrated that OR3A4 influenced biologic functions in gastric cancer cells via regulating the activation of PDLIM2, MACC1, NTN4, and GNB2L1. Our results reveal OR3A4 as an oncogenic lncRNA that promotes tumor progression, Therefore, lncRNAs might function as key regulatory hubs in gastric cancer progression.
Ji MH, Kim SK, Kim CY, et al.Physiological Expression and Accumulation of the Products of Two Upstream Open Reading Frames mrtl and MycHex1 Along With p64 and p67 Myc From the Human c-myc Locus.
J Cell Biochem. 2016; 117(6):1407-18 [PubMed
] Related Publications
In addition to the canonical c-Myc p64 and p67 proteins, the human c-myc locus encodes two distinct proteins, mrtl (myc-related translation/localization regulatory factor) and MycHex1 (Myc Human Exon 1), from the upstream open reading frames within the 5'-untranslated region of the c-myc P0 mRNA. The aim of this study is to examine simultaneously, for the first time, mrtl, MycHex1, c-Myc p64, and p67 in human tumor cell lines and pediatric brain tumor tissues. Western blot analysis demonstrated endogenous mrtl, MycHex1, c-Myc p64, and p67 simultaneously. The relative abundance of mrtl and MycHex1 were consistent among a variety of human tumor cell lines, and the relative intensities of mrtl and MycHex1 correlated positively. Confocal imaging revealed mrtl predominantly localized to the nuclear envelope, along with prominent reticular pattern in the cytoplasm. MycHex1 was observed as a series of bright foci located within the nucleus, a subset of which colocalized with fibrillarin. mrtl and MycHex1 co-immunoprecipitated with RACK1, c-Myc, fibrillarin, coilin, and with each other. These findings suggest that mrtl and MycHex1 have multiple interaction partners in both the nucleus and cytoplasm. Sequence analyses confirmed a known polymorphism of mrtl at base 1965 (G>T) and new mutations at bases 1900 (C>G) and 1798 (C>G). Evidence is presented for expression and stable accumulation of all four proteins encoded by three distinct non-overlapping open reading frames within the human c-myc locus. Additional work is warranted to further elucidate the functional or regulatory roles of these molecules in regulation of c-Myc and in oncogenesis.
eIF6 is an antiassociation factor that regulates the availability of active 80S. Its activation is driven by the RACK1/PKCβ axis, in a mTORc1 independent manner. We previously described that eIF6 haploinsufficiency causes a striking survival in the Eμ-Myc mouse lymphoma model, with lifespans extended up to 18 months. Here we screen for eIF6 expression in human cancers. We show that Malignant Pleural Mesothelioma tumors (MPM) and a MPM cell line (REN cells) contain high levels of hyperphosphorylated eIF6. Enzastaurin is a PKC beta inhibitor used in clinical trials. We prove that Enzastaurin treatment decreases eIF6 phosphorylation rate, but not eIF6 protein stability. The growth of REN, in vivo, and metastasis are reduced by either Enzastaurin treatment or eIF6 shRNA. Molecular analysis reveals that eIF6 manipulation affects the metabolic status of malignant mesothelioma cells. Less glycolysis and less ATP content are evident in REN cells depleted for eIF6 or treated with Enzastaurin (Anti-Warburg effect). We propose that eIF6 is necessary for malignant mesothelioma growth, in vivo, and can be targeted by kinase inhibitors.
Chen L, Min L, Wang X, et al.Loss of RACK1 Promotes Metastasis of Gastric Cancer by Inducing a miR-302c/IL8 Signaling Loop.
Cancer Res. 2015; 75(18):3832-41 [PubMed
] Related Publications
Gastric cancer remains the third leading cause of cancer-related mortality worldwide, and invasion and metastasis of gastric cancer represent the major reason for its poor prognosis. In this study, we found that loss of the receptor for activated C-kinase 1 (RACK1) promoted the metastasis of gastric cancer by enhancing the autocrine expression of IL8 in vitro and in vivo. microRNA (miRNA; miR) array identified that RACK1 modulated the expression of a series of miRNAs, including the miR-302 cluster, and RACK1 modulated the IL8 expression and tumor invasion through miRNA-302c. Moreover, upregulation of IL8 in turn decreased the level of miRNA-302c and induced IL8 expression in a feedback manner. Tissue microarray also indicated that RACK1 was correlated with invasion/metastasis phenotype, IL8 expression, as well as 5-year survival in clinical cases of gastric cancer. Together, our results imply that loss of RACK1 in gastric cancer links epigenetics to inflammatory cytokines to promote tumor metastasis.
Zhou T, Lv X, Guo X, et al.RACK1 modulates apoptosis induced by sorafenib in HCC cells by interfering with the IRE1/XBP1 axis.
Oncol Rep. 2015; 33(6):3006-14 [PubMed
] Related Publications
Sorafenib is one of the preferred drugs for the treatment of advanced primary hepatocellular carcinoma (HCC). However, its side-effects and acquired resistance limit its use. The unfolded protein response (UPR) induced by chemotherapeutics has been demonstrated to be required for tumor cells to maintain malignancy and therapy resistance. Activation of the IRE1/XBP1 pathway during the UPR is important for tumor survival under pathophysiological conditions. In the present study, we found that the UPR was activated and RACK1 was overexpressed in three human HCC cell lines and in HCC samples. Activation of the IRE1/XBP1 signaling pathway plays a protective role when HCC cells encounter endoplasmic reticulum (ER) stress due to in vitro sorafenib treatment. We then found that the interaction between IRE1 and RACK1 was essential for the activation of IRE1 signaling in sorafenib-treated cells. Exogenous overexpression of RACK1 enhanced the phosphorylation level of IRE1 and increased XBP1 mRNA splicing activity, which protected the HCC cells from sorafenib-induced apoptosis. However, the re-expression of RACK1 led HCC cells to regain susceptibility to sorafenib-induced apoptosis. Taken together, the present study suggests that the RACK1/IRE1 complex may contribute to activation of the UPR in HCC cells. Targeting RACK1 in combination with sorafenib administration is a potential strategy for clinical trials of advanced HCC treatment.
Cho IR, Kaowinn S, Moon J, et al.Oncotropic H-1 parvovirus infection degrades HIF-1α protein in human pancreatic cancer cells independently of VHL and RACK1.
Int J Oncol. 2015; 46(5):2076-82 [PubMed
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Overexpression of HIF-1α, a transcription factor responsive to hypoxia, is frequently observed in malignant tumors, which sometimes show resistance to chemotherapy and radiation therapy. Consequently, decrease of HIF-1α through virotherapy offers a logical strategy for the treatment of aggressive tumors. In this study, we found that infection with the oncolytic H-1 parvovirus decreased HIF-1α protein levels in pancreatic cancer cells under CoCl2 or hypoxia. The H-1 virus-induced decrease of HIF-1α was regulated by a proteasome-mediated pathway. Suppression of VHL, an E3 ligase and a critical regulator of HIF-1α, or enforced expression of UCP, an E2 ubiquitin-conjugating enzyme, failed to inhibit the H-1 virus-induced decrease of HIF-1α. Furthermore, siRNA-mediated suppression of RACK1, another regulator of HIF-1α, did not prevent H-1 viral infection from lowering HIF-1α protein levels. Although decrease of HIF-1α was observed after H-1 viral infection, constitutive expression of HIF-1α limited H-1 viral replication. After combined treatment with H-1 parvovirus and YC-1, an inhibitor of HIF-1α, the apoptosis of pancreatic cancer cells was greater than after treatment with H-1 virus alone or YC-1 alone. Accordingly, we propose that H-1 parvovirus could be used with YC-1 as a potential therapeutic agent against aggressive tumors exhibiting hypoxia and increased levels of HIF-1α.
BACKGROUND: RACK1 is known to be involved in tumor progression, and its prognostic value on many kinds of tumors has been identified. However, there are limited studies about the functional role of RACK1 in esophageal squamous cell carcinoma (ESCC).
PATIENTS AND METHODS: RACK1 expression was examined in 100 ESCC tissue samples using immunohistochemistry staining. RACK1 was knocked-down in ESCC cell lines by shRNA. The effects on cell proliferation, invasion and migration were examined in ESCC cell lines and nude mouse model. Vimentin and E-cadherin were introduced to further study the association between RACK1 and EMT.
RESULTS: RACK1 expression was significantly associated with the tumor length (P = 0.012), diameter<3 cm (P = 0.047), T stage (P = 0.032), and lymph node metastasis (P = 0.038), respectively. Kaplan-Meier survival analysis and Cox analyses revealed RACK1 expression was an independent predictor for OS (P = 0.030) and DFS (P = 0.027) in ESCC. Down-regulation of RACK1 inhibited cell proliferation, along with invasion and migration in vitro and in vivo. A significant positive correlation between RACK1 expression and vimentin (P = 0.0190) and an inverse correlation between RACK1 expression and E-cadherin (P = 0.0047) were found.
CONCLUSIONS: RACK1 predicted poor prognosis in ESCC, promoted tumor progression, and was involved in EMT of ESCC.
BACKGROUND: This study was conducted to identify genetic polymorphisms associated with the prognosis of patients with early stage NSCLC.
MATERIALS AND METHODS: We genotyped 1,969 potentially functional single nucleotide polymorphisms (SNPs) of 1,151 genes involved in carcinogenesis in 166 NSCLC patients who underwent curative surgery, using the Affymetrix custom-made GeneChip. A replication study was performed in an independent cohort of 626 patients.
RESULTS: Fifty six SNPs which were associated with both overall survival (OS) and disease-free survival (DFS) with log-rank P values < 0.05 in discovery set were selected for validation. Among those, five SNPs (RACK1 rs1279736C>A and rs3756585T>G, C3 rs2287845T>C, PCAF rs17006625A>G, and PCM1 rs17691523C>G) were found to be significantly associated with survival in the same direction as the discovery set. In combined analysis, the rs1279736C>A and rs3756585T>G were most significantly associated with OS and DFS in multivariate analysis (P for OS = 4 × 10⁻⁵ and 7 × 10⁻⁵, respectively; and P for DFS = 0.003, both; under codominant model). In vitro promoter assay and electrophoretic mobility shift assay revealed that the rs3756585 T-to-G change increased promoter activity and transcription factor binding of RACK1.
CONCLUSIONS: We identified five SNPs, especially RACK1 rs3756585T>G, as markers for prognosis of patients with surgically resected NSCLC.
Research on innate immune signaling and regulation has recently focused on pathogen recognition receptors (PRRs) and their signaling pathways. Members of PRRs sense diverse microbial invasions or danger signals, and initiate innate immune signaling pathways, leading to proinflammatory cytokines production, which, in turn, instructs adaptive immune response development. Despite the diverse functions employed by innate immune signaling to respond to a variety of different pathogens, the innate immune response must be tightly regulated. Otherwise, aberrant, uncontrolled immune responses will lead to harmful, or even fatal, consequences. Therefore, it is essential to better discern innate immune signaling and many regulators, controlling various signaling pathways, have been identified. In this review, we focus on the recent advances in our understanding of the activation and regulation of innate immune signaling in the host response to pathogens and cancer.
Yu S, Xu Z, Zou C, et al.Ion channel TRPM8 promotes hypoxic growth of prostate cancer cells via an O2 -independent and RACK1-mediated mechanism of HIF-1α stabilization.
J Pathol. 2014; 234(4):514-25 [PubMed
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The growth adaptation of cancer cells to a hypoxic tumour microenvironment is mostly regulated by hypoxia-induced transcription factor HIF-1. HIF-1 transcriptional activity is strictly controlled by protein levels of the HIF-1α subunit, which is tightly regulated by a well-characterized O2 -dependent ubiquitin ligase-proteasomal degradation pathway. The cold-sensitive Ca(2+) channel protein TRPM8 exhibits increased expression in advanced prostate cancer. However, its exact functional roles in prostate cancer growth regulation are unclear and controversial. In this work, we show that TRPM8 promotes in vitro hypoxic growth capacities, drug resistance, and in vivo tumourigenicity, accompanied with enhanced HIF-1α protein levels. These effects are further potentiated by TRPM8 agonists but suppressed by TRPM8 gene knockdown and blocking with antagonists or TRPM8 antibody. TRPM8-induced suppression of HIF-1α ubiquitination and enhanced HIF-1 transactivation were attenuated by forced RACK1 expression and TRPM8 overexpression reduced phospho-RACK1 levels, thus affecting its dimerization status, and promoted RACK1 binding to HIF-1α and calcineurin. These data indicate that TRPM8-induced increase of HIF-1α protein in hypoxia- or normoxia-exposed prostate cancer cells was mediated through a newly characterized Ca(2+) -dependent but O2 -independent mechanism involving binding of RACK1 to HIF-1α and RACK1-mediated ubiquitination of HIF-1α. Collectively, our study not only provides a mechanistic insight into how TRPM8 promotes the hypoxic growth adaptation of cancer cells via its promotion of RACK1-mediated stabilization of HIF-1α but also suggests a potential therapeutic strategy for prostate cancer by targeting TRPM8.
PDLIM2 is a cytoskeletal and nuclear PDZ-LIM domain protein that regulates the stability of Nuclear Factor kappa-B (NFκB) and other transcription factors, and is required for polarized cell migration. PDLIM2 expression is suppressed by methylation in different cancers, but is strongly expressed in invasive breast cancer cells that have undergone an Epithelial Mesenchymal Transition (EMT). PDLIM2 is also expressed in non-transformed breast myoepithelial MCF10A cells and here we asked whether it is important for maintaining the polarized, epithelial phenotype of these cells. Suppression of PDLIM2 in MCF10A cells was sufficient to disrupt cell polarization and acini formation with increased proliferation and reduced apoptosis in the luminal space compared to control acini with hollow lumina. Spheroids with suppressed PDLIM2 exhibited increased expression of cell-cell and cell-matrix adhesion proteins including beta 1 (β1) integrin. Interestingly, levels of the Insulin-like growth factor 1 receptor (IGF-1 R) and Receptor of activated protein kinase C 1 (RACK1), which scaffolds IGF-1R to β1 integrin, were also increased, indicating a transformed phenotype. Focal Adhesion Kinase (FAK) and cofilin phosphorylation, and RhoA Guanosine Triphosphatase (GTPase) activity were all enhanced in these spheroids compared to control acini. Importantly, inhibition of either FAK or Rho Kinase (ROCK) was sufficient to rescue the polarity defect. We conclude that PDLIM2 expression is essential for feedback regulation of the β1-integrin-RhoA signalling axis and integration of cellular microenvironment signals with gene expression to control the polarity of breast epithelial acini structures. This is a mechanism by which PDLIM2 could mediate tumour suppression in breast epithelium.
Hu F, Tao Z, Shen Z, et al.Down-regulation of EphB4 phosphorylation is necessary for esophageal squamous cell carcinoma tumorigenecity.
Tumour Biol. 2014; 35(7):7225-32 [PubMed
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Eph/ephrin signaling system plays a very important role in the tumorigenesis and the formation of blood vessel. However, the function of EphB4 and its ligand ephrin B2 in the carcinogenesis of esophageal squamous cell carcinoma (ESCC) is not fully understood. Here, it was found that the expression of EphB4 was up-regulated in ESCC tissues compared with the paired normal tissues, while ephrin B2 was down-regulated in ESCC samples. Phosphorylation of EphB4 induced by its ligand ephrin B2-Fc inhibited the growth, migration and colony formation of ESCC cells. Moreover, over-expression of EphB4 or EphB4 kinase dead mutant (EphB4 KD) in ESCC cells promoted cell growth and migration, suggesting EphB4 promoted cell growth and migration independent of its kinase activity. Furthermore, we found that EphB4 interacted with the adaptor protein RACK1 and RACK1 decreased the phosphorylation level of EphB4. Taken together, our study revealed the important function and regulation of EphB4 in the progression of ESCC and suggested EphB4 as a novel target for the treatment of ESCC.
Zhou Z, Liu F, Zhang ZS, et al.Human rhomboid family-1 suppresses oxygen-independent degradation of hypoxia-inducible factor-1α in breast cancer.
Cancer Res. 2014; 74(10):2719-30 [PubMed
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Intermittent oxygen deficiency in cancers promotes prolonged inflammation, continuous angiogenesis, and increased drug resistance. Hypoxia-inducible factor-1 (HIF1) has a pivotal role in the regulation of cellular responses to oxygen deficiency. The α-subunit of HIF1 (HIF1α) is degraded in normoxia but stabilized in hypoxia. However, the molecular mechanism that controls oxygen-independent degradation of HIF1α has remained elusive. Human rhomboid family-1 (RHBDF1) is a member of a large family of nonprotease rhomboids whose function is basically unknown. We report here that RHBDF1 expression in breast cancer is highly elevated and is strongly correlated with escalated disease progression, metastasis, poor prognosis, and poor response to chemotherapy. We show that RHBDF1 interaction with the receptor of activated protein-C kinase-1 (RACK1) in breast cancer cells prevents RACK1-assisted, oxygen-independent HIF1α degradation. In addition, we show that the HIF1α-stabilizing activity of RHBDF1 diminishes when the phosphorylation of a tyrosine residue on the RHBDF1 molecule is inhibited. These findings are consistent with the view that RHBDF1 is a critical component of a molecular switch that regulates HIF1α stability in cancer cells in hypoxia and that RHBDF1 is of potential value as a new target for cancer treatment.
Jin S, Mu Y, Wang X, et al.Overexpressed RACK1 is positively correlated with malignant degree of human colorectal carcinoma.
Mol Biol Rep. 2014; 41(5):3393-9 [PubMed
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RACK1 is a crucial scaffold and anchoring protein, which plays a vital role in multiple signaling pathways of tumorigenesis. The aim of the present study was to identify the correlation between expressions of RACK1 and malignant degrees in colorectal carcinoma (CRC) patients. All together 157 CRC patients were enrolled, and their clinical data were analyzed. Expressions of RACK1 in CRC and pericarcinous tissues in these patients were determined by RT-PCR, Western-blot, and immunohistochemistry, respectively. The correlation between RACK1 expressions and histological grades, as well as lymph node metastasis was evaluated. Results showed that the expressions of RACK1 were positively correlated with differentiation level and lymph node metastasis in CRC patients.