|Gene:||RBM5; RNA binding motif protein 5|
|Aliases: || G15, H37, RMB5, LUCA15 |
|Summary:||This gene is a candidate tumor suppressor gene which encodes a nuclear RNA binding protein that is a component of the spliceosome A complex. The encoded protein plays a role in the induction of cell cycle arrest and apoptosis through pre-mRNA splicing of multiple target genes including the tumor suppressor protein p53. This gene is located within the tumor suppressor region 3p21.3, and may play a role in the inhibition of tumor transformation and progression of several malignancies including lung cancer. [provided by RefSeq, Oct 2011]|
|Databases:||OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene|
|Protein:||RNA-binding protein 5|
|Updated:||14 December, 2014|
What does this gene/protein do?
Graph generated 14 December 2014 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 14 December, 2014 using data from PubMed, MeSH and CancerIndex
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
Search the Epigenomics database and view relevant gene tracks of samples.
Latest Publications: RBM5 (cancer-related)
Zhang L, Zhang Q, Yang Y, Wu CThe RNA recognition motif domains of RBM5 are required for RNA binding and cancer cell proliferation inhibition.
Biochem Biophys Res Commun. 2014; 444(3):445-50 [PubMed
] Related Publications
RBM5 is a known putative tumor suppressor gene that has been shown to function in cell growth inhibition by modulating apoptosis. RBM5 also plays a critical role in alternative splicing as an RNA binding protein. However, it is still unclear which domains of RBM5 are required for RNA binding and related functional activities. We hypothesized the two putative RNA recognition motif (RRM) domains of RBM5 spanning from amino acids 98-178 and 231-315 are essential for RBM5-mediated cell growth inhibition, apoptosis regulation, and RNA binding. To investigate this hypothesis, we evaluated the activities of the wide-type and mutant RBM5 gene transfer in low-RBM5 expressing A549 cells. We found that, unlike wild-type RBM5 (RBM5-wt), a RBM5 mutant lacking the two RRM domains (RBM5-ΔRRM), is unable to bind RNA, has compromised caspase-2 alternative splicing activity, lacks cell proliferation inhibition and apoptosis induction function in A549 cells. These data provide direct evidence that the two RRM domains of RBM5 are required for RNA binding and the RNA binding activity of RBM5 contributes to its function on apoptosis induction and cell growth inhibition.Related: Lung Cancer
Cancer-associated fibroblasts (CAFs) are crucial co-mediators of breast cancer progression. Estrogen is the predominant driving force in the cyclic regulation of the mammary extracellular matrix, thus potentially affecting the tumor-associated stroma. Recently, a third estrogen receptor, estrogen (G-protein-coupled) receptor (GPER), has been reported to be expressed in breast CAFs. In this study, GPER was detected by immunohistochemical analysis in stromal fibroblasts of 41.8% (59/141) of the primary breast cancer samples. GPER expression in CAFs isolated from primary breast cancer tissues was confirmed by immunostaining and RT-PCR analyses. Tamoxifen (TAM) in addition to 17β-estradiol (E₂) and the GPER agonist G1 activated GPER, resulting in transient increases in cell index, intracellular calcium, and ERK1/2 phosphorylation. Furthermore, TAM, E₂, and G1 promoted CAF proliferation and cell-cycle progression, both of which were blocked by GPER interference, the selective GPER antagonist G15, the epidermal growth factor receptor (EGFR) inhibitor AG1478, and the ERK1/2 inhibitor U0126. Importantly, TAM as well as G1 increased E₂ production in breast CAFs via GPER/EGFR/ERK signaling when the substrate of E₂, testosterone, was added to the medium. GPER-induced aromatase upregulation was probably responsible for this phenomenon, as TAM- and G1-induced CYP19A1 gene expression was reduced by GPER knockdown and G15, AG1478, and U0126 administration. Accordingly, GPER-mediated CAF-dependent estrogenic effects on the tumor-associated stroma are conceivable, and CAF is likely to contribute to breast cancer progression, especially TAM resistance, via a positive feedback loop involving GPER/EGFR/ERK signaling and E₂ production.Related: Breast Cancer
Chen Y, Li Z, He Y, et al.Estrogen and pure antiestrogen fulvestrant (ICI 182 780) augment cell-matrigel adhesion of MCF-7 breast cancer cells through a novel G protein coupled estrogen receptor (GPR30)-to-calpain signaling axis.
Toxicol Appl Pharmacol. 2014; 275(2):176-81 [PubMed
] Related Publications
Fulvestrant (ICI 182 780, ICI) has been used in treating patients with hormone-sensitive breast cancer, yet initial or acquired resistance to endocrine therapies frequently arises and, in particular, cancer recurs as metastasis. We demonstrate here that both 17-beta-estradiol (E2) and ICI enhance cell adhesion to matrigel in MCF-7 breast cancer cells, with increased autolysis of calpain 1 (large subunit) and proteolysis of focal adhesion kinase (FAK), indicating calpain activation. Additionally, either E2 or ICI induced down-regulation of estrogen receptor α without affecting G protein coupled estrogen receptor 30 (GPR30) expression. Interestingly, GPR30 agonist G1 triggered calpain 1 autolysis but not calpain 2, whereas ER agonist diethylstilbestrol caused no apparent calpain autolysis. Furthermore, the actions of E2 and ICI on calpain and cell adhesion were tremendously suppressed by G15, or knockdown of GPR30. E2 and ICI also induced phosphorylation of extracellular regulated protein kinases 1 and 2 (ERK1/2), and suppression of ERK1/2 phosphorylation by U0126 profoundly impeded calpain activation triggered by estrogenic and antiestrogenic stimulations indicating implication of ERK1/2 in the GPR30-mediated action. Lastly, the E2- or ICI-induced cell adhesion was dramatically impaired by calpain-specific inhibitors, ALLN or calpeptin, suggesting requirement of calpain in the GPR30-associated action. These data show that enhanced cell adhesion by E2 and ICI occurs via a novel GPR30-ERK1/2-calpain pathway. Our results indicate that targeting the GPR30 signaling may be a potential strategy to reduce metastasis and improve the efficacy of antiestrogens in treatment of advanced breast cancer.Related: Breast Cancer Signal Transduction
Bechara EG, Sebestyén E, Bernardis I, et al.RBM5, 6, and 10 differentially regulate NUMB alternative splicing to control cancer cell proliferation.
Mol Cell. 2013; 52(5):720-33 [PubMed
] Related Publications
RBM5, a regulator of alternative splicing of apoptotic genes, and its highly homologous RBM6 and RBM10 are RNA-binding proteins frequently deleted or mutated in lung cancer. We report that RBM5/6 and RBM10 antagonistically regulate the proliferative capacity of cancer cells and display distinct positional effects in alternative splicing regulation. We identify the Notch pathway regulator NUMB as a key target of these factors in the control of cell proliferation. NUMB alternative splicing, which is frequently altered in lung cancer, can regulate colony and xenograft tumor formation, and its modulation recapitulates or antagonizes the effects of RBM5, 6, and 10 in cell colony formation. RBM10 mutations identified in lung cancer cells disrupt NUMB splicing regulation to promote cell growth. Our results reveal a key genetic circuit in the control of cancer cell proliferation.Related: Lung Cancer
RBM5 (RNA-binding motif protein 5, also named H37/LUCA-15) gene from chromosome 3p21.3 has been demonstrated to be a tumor suppressor. Current researches in vitro confirm that RBM5 can suppress the growth of lung adenocarcinoma cells by inducing apoptosis. There is still no effective model in vivo, however, that thoroughly investigates the effect and molecular mechanism of RBM5 on lung adenocarcinoma.METHOD:
We established the transplanted tumor model on BALB/c nude mice using the A549 cell line. The mice were treated with the recombinant plasmids carried by attenuated Salmonella to induce the overexpression of RBM5 in tumor tissues. RBM5 overexpression was confirmed by immunohistochemistry staining. H&E staining was performed to observe the histological performance on plasmids-treated A549 xenografts. Apoptosis was assessed by TUNEL staining with a TUNEL detection kit. Apoptosis-regulated genes were detected by Western blot.RESULTS:
We successful established the lung adenocarcinoma animal model in vivo. The growth of tumor xenografts was significantly retarded on the mice treated with pcDNA3.1-RBM5 carried by attenuated Salmonella compared to that on mice treated with pcDNA3.1. Overexpression of RBM5 enhanced the apoptosis in tumor xenografts. Furthermore, the expression of Bcl-2 protein was decreased significantly, while the expression of BAX, TNF-α, cleaved caspase-3, cleaved caspase-8, cleaved caspase-9 and cleaved PARP proteins was significantly increased in the pcDNA3.1-RBM5-treated mice as compared to that in the control mice.CONCLUSIONS:
In this study, we established a novel animal model to determine RBM5 function in vivo, and concluded that RBM5 inhibited tumor growth in mice by inducing apoptosis. The study suggests that although RBM5's involvement in the death receptor-mediated apoptotic pathway is still to be investigated, RBM5-mediated growth suppression, at least in part, employs regulation of the mitochondrial apoptotic pathways.Related: Apoptosis Lung Cancer Mitochondrial Mutations in Cancer Signal Transduction TNF
Recent studies have indicated that the nuclear RNA-binding protein RBM5 has the ability to modulate apoptosis and suppress tumor growth. The aim of this study is to investigate the expression of RBM5 in human prostate cancer and its mechanism of tumor suppression.METHODS:
The expression of RBM5 protein in cancerous prostatic tissues and normal tissues was examined by IHC. PC-3 cell line was used to determine the apoptotic function of RBM5 in vitro. PC-3 cells were transiently transfected with pcDNA3.1-RBM5. Cell viability was determined by MTT assay. Rhodamine 123 staining and Annexin V analysis were performed to observe the apoptotic activity of PC-3 cells overexpressing RBM5. Expression of apoptosis-related genes was assessed by western blot.RESULTS:
The expression of RBM5 protein was significantly decreased in cancerous prostatic tissues compared to the normal tissues. PC-3 cells overexpressing RBM5 showed not only significant growth inhibition compared with the vector controls, but also dysfunction of mitochondrial membrane potential and increased apoptotic activity. To further define RBM5 function in apoptotic pathways, we investigated differential expression profiles of various BH3-only proteins including Bid, Bad, and Bim, and apoptosis regulatory proteins include P53, cleaved caspase9, and cleaved caspase3. We found that the expression of both BH3-only proteins and apoptosis regulatory proteins was increased in RBM5 transfected cells.CONCLUSION:
The expression of RBM5 protein was significantly decreased in cancerous prostatic tissues, which suggests that RBM5 plays an important role in the pathogenesis of prostate cancer. RBM5 may induce the apoptosis of prostate cancer PC-3 cells by modulating the mitochondrial apoptotic pathway, and thus RBM5 might be a promising target for gene therapy on prostate cancer.Related: Apoptosis Prostate Cancer
Masilamani TJ, Rintala-Maki ND, Wang K, Sutherland LCDownregulating activated epidermal growth factor receptor has no effect on RBM5 expression.
Chin Med J (Engl). 2012; 125(13):2378-81 [PubMed
] Related Publications
We were interested in determining how the tumor suppressor gene RBM5 is regulated in lung cancers. Previous studies suggested that the gene expression is related to histological subtype and smoking exposure, since in small cell lung cancers the RBM5 gene is deleted whereas in non-small cell lung carcinomas (NSCLC) RBM5 expression is reduced. Of particular interest was the recent finding that in lung adenocarcinomas, a histological subtype of NSCLC, smoking exposure correlated with mutational activity in the transforming growth factor alpha (TGF-a) signaling pathway. Lung adenocarcinomas from smokers were associated with activating KRAS mutations, whereas lung adenocarcinomas from never-smokers were associated with activating epidermal growth factor receptor (EGFR) mutations. We hypothesized that inhibition of RBM5 in lung adenocarcinomas is achieved indirectly via these activating mutations. The objective of the research described herein was to determine if EGFR activation and RBM5 expression are negatively correlated.METHODS:
EGFR expression in the lung adenocarcinoma cell line NCI-H1975 was inhibited using small interfering RNA. RBM5 expression was examined by real-time quantitative polymerase chain reaction and Western blotting.RESULTS:
Reduced EGFR expression did not correlate with any change in RBM5 expression at either the RNA or protein level.CONCLUSION:
These results suggest that RBM5 expression is not directly regulated by EGFR in non-smoker related lung adenocarinomas, and that some other mechanism operates to inhibit either the expression or function of this potential tumour suppressor in lung cancers that retain the RBM5 gene.Related: Lung Cancer
The loss of tumor suppressor gene (TSG) function is a critical step in the pathogenesis of human lung cancer. RBM5 (RNA-binding motif protein 5, also named H37/LUCA-15) gene from chromosome 3p21.3 demonstrated tumor suppressor activity. However, the role of RBM5 played in the occurrence and development of lung cancer is still not well understood.METHOD:
Paired non-tumor and tumor tissues were obtained from 30 adenocarcinomas. The expression of RBM5 mRNA and protein was examined by RT-PCR and Western blot. A549 cell line was used to determine the apoptotic function of RBM5 in vitro. A549 cells were transiently transfected with pcDNA3.1-RBM5. AnnexinV analysis was performed by flow cytometry. Expression of Bcl-2, cleaved caspase-3, caspase-9 and PAPP proteins in A549 lung cancer cells and the A549 xenograft BALB/c nude mice model was determined by Western blot. Tumor suppressor activity of RBM5 was also examined in the A549 xenograft model treated with pcDNA3.1-RBM5 plasmid carried by attenuated Salmonella typhi Ty21a.RESULT:
The expression of RBM5 mRNA and protein was decreased significantly in adenocarcinoma tissues compared to that in the non-tumor tissues. In addition, as compared to the vector control, a significant growth inhibition of A549 lung cancer cells was observed when transfected with pcDNA3.1-RBM5 as determined by cell proliferation assay. We also found that overexpression of RBM5 induced both early and late apoptosis in A549 cells using AnnexinV/PI staining as determined by flow cytometry. Furthermore, the expression of Bcl-2 protein was decreased, whereas the expression of cleaved caspase-3, caspase-9 and PARP proteins was significantly increased in the RBM5 transfected cells; similarly, expression of decreased Bcl-2 and increased cleaved caspase-3 proteins was also examined in the A549 xenograft model. More importantly, we showed that accumulative and stable overexpression of RBM5 in the A549 xenograft BALB/c nude mice model significantly inhibited the tumor growth rate in vivo as compared to that in the control.CONCLUSION:
Our study demonstrates that RBM5 can inhibit the growth of lung cancer cells and induce apoptosis both in vitro and in vivo, which suggests that RBM5 might be used as a potential biomarker or target for lung cancer diagnosis and chemotherapy. Moreover, we propose a novel animal model set up in BALB/c nude mice treated with attenuated Salmonella as a vector carrying plasmids to determine RBM5 function in vivo.Related: Apoptosis Lung Cancer
Li P, Wang K, Zhang J, et al.The 3p21.3 tumor suppressor RBM5 resensitizes cisplatin-resistant human non-small cell lung cancer cells to cisplatin.
Cancer Epidemiol. 2012; 36(5):481-9 [PubMed
] Related Publications
Increasing RBM5 levels inhibit tumor cell growth and promote apoptosis. In this study, we investigated the role of RBM5 in the cisplatin resistance observed in human lung non-small cell lung cancer cells and evaluated the effect of RBM5 modulation on cell growth inhibition and apoptosis induced by cisplatin in the parental non-small cell lung cancer cells A549 and their cisplatin resistant counterparts, A549/DDP cells.METHODS:
RBM5 mRNA and protein expression in the A549 and A549/DDP cells was analyzed by semi-quantitative RT-PCR and western blot. The A549/DDP cells were then transfected with a pcDNA3-RBM5 plasmid, and an RBM5-specific siRNA was transfected into A549 cells, prior to treatment with cisplatin. Semi-quantitative RT-PCR and western blot analyses were performed to confirm the expression of RBM5 mRNA or protein, and knockdown of RBM5 mRNA or protein, respectively. MTT assays were used to evaluate chemosensitivity to cisplatin. Apoptosis was assessed by DAPI nuclear staining and flow cytometric analysis with an Annexin-V-FITC apoptosis kit. Cytosolic cytochrome c, cleaved caspase-3 and cleaved caspase-9 were detected by western blot.RESULTS:
The expression of RBM5 mRNA and protein was significantly reduced in the A549/DDP cells compared with the A549 cells. Exogenous expression of RBM5 by the pcDNA3-RBM5 resensitized the response of A549/DDP to cisplatin, resulting in a significant increase in tumor-suppressing activity induced by cisplatin. In contrast, downregulation of RBM5 with siRNA in the A549 cells inhibited cisplatin-induced apoptosis. We also found that the RBM5-enhanced chemosensitivity was associated with the release of cytochrome c into the cytosol, activation of caspase-9 and the downstream marker caspase-3.CONCLUSION:
Our results demonstrate that RBM5 may serve as a biomarker with the ability to predict a response to cisplatin. It may also act as a prognostic indicator in lung cancer patients. Our findings suggest that there may be clinical utility for ectopic RBM5 such as enhancing and resensitizing nonresponders to cisplatin.Related: Apoptosis Non-Small Cell Lung Cancer Cisplatin Lung Cancer
RNA binding motif 5 (RBM5) is a tumor suppressor gene that modulates apoptosis through the regulation of alternative splicing of apoptosis-related genes. This study aimed to detect RBM5 expression in non-small cell lung cancer (NSCLC) and to associate RBM5 expression with clinicopathological data from NSCLC patients and EGFR and KRAS expression to better understand the potential role of RBM5 in NSCLC.METHOD:
Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were performed to detect expression of mRNA and protein, respectively, of RBM5, EGFR and KRAS in 120 paired non-tumor and tumor samples of NSCLC.RESULTS:
The data showed that expression of RBM5 mRNA and protein was significantly reduced in NSCLC compared to normal tissues, whereas expression of both EGFR and KRAS genes was increased in NSCLC compared to normal tissues. Furthermore, the reduced RBM5 protein expression correlated with smoking status, tumor stage and lymph node metastasis of NSCLC, while overexpression of EGFR and KRAS proteins correlated with tumor stage and lymph node metastasis of NSCLC. Overexpression of KRAS protein was more frequent in smokers with NSCLC. In addition, expression of RBM5 mRNA and protein was negatively correlated with expression of EGFR and KRAS mRNA and protein in NSCLC tissues.CONCLUSION:
This study suggests further evaluation of RBM5 expression is warranted for use of RBM5 as a biomarker for NSCLC patients.Related: Non-Small Cell Lung Cancer Lung Cancer KRAS gene EGFR
Notas G, Kampa M, Pelekanou V, Castanas EInterplay of estrogen receptors and GPR30 for the regulation of early membrane initiated transcriptional effects: A pharmacological approach.
Steroids. 2012; 77(10):943-50 [PubMed
] Related Publications
Estrogens exert their effect through ERα and ERβ intracellular transcription factors and rapid, usually membrane-initiated receptors, influencing cytosolic signaling and transcription. The nature of extranuclear estrogen elements has not been elucidated so far; classical or alternatively transcribed ER isoforms (ERα36, ERα46) anchored to the plasma membrane and GPR30 (GPER1) have been reported to exert early estrogen actions. Here, we used E2-BSA, an impermeable estradiol analog for a transcriptome analysis in four GREP1 positive breast cancer cell lines with different estrogen receptor profiles (T47D, MCF-7, MDA-MB-231 and SKBR3) in order to evaluate GPER1 transcriptional effects. Early effects of E2-BSA were assayed after 3h of incubation, in the absence/presence of ICI182,780 (ER-inhibitor) or G15 (GREP1-specific inhibitor). E2-BSA specifically modified 277-549 transcripts in the different cell lines. Two different clusters of transcripts could be identified: (1) the majority of transcripts were inhibited by both ICI182,780 and G15, suggesting an interaction of E2-BSA with a common ER-related element, or a direct ER-GPER1 interaction; (2) a small number of G15-only modified transcripts, in two cell lines (T47D and SKBR3 cells), indicative of specific GPER1-related effects. The latter transcripts were significantly related to pathways including FOXA2/FOXA3 transcription factor networks, RNA-Polymerases Transcription Regulation and lipid metabolism, while ICI/G15 inhibited transcripts affected pathways related to apoptosis, erythropoietin signaling, metabolic effects through the citric acid cycle, IL-4 and IL-5 mediated events and homologous DNA recombination. Finally, we review the current literature of GPER1 actions, in view of our results of ER-dependent and independent GPER1-modified pathways.Related: Breast Cancer
Most patients with ovarian cancer are diagnosed with advanced stage disease (i.e., stage III-IV), which is associated with a poor prognosis. Differentially expressed genes (DEGs) in stage III serous ovarian carcinoma compared to normal tissue were screened by a new differential display method, the annealing control primer (ACP) system. The potential targets for markers that could be used for diagnosis and prognosis, for stage III serous ovarian cancer, were found by cluster and survival analysis.METHODS:
The ACP-based reverse transcriptase polymerase chain reaction (RT PCR) technique was used to identify DEGs in patients with stage III serous ovarian carcinoma. The DEGs identified by the ACP system were confirmed by quantitative real-time PCR. Cluster analysis was performed on the basis of the expression profile produced by quantitative real-time PCR and survival analysis was carried out by the Kaplan-Meier method and Cox proportional hazards multivariate model; the results of gene expression were compared between chemo-resistant and chemo-sensitive groups.RESULTS:
A total of 114 DEGs were identified by the ACP-based RT PCR technique among patients with stage III serous ovarian carcinoma. The DEGs associated with an apoptosis inhibitory process tended to be up-regulated clones while the DEGs associated with immune response tended to be down-regulated clones. Cluster analysis of the gene expression profile obtained by quantitative real-time PCR revealed two contrasting groups of DEGs. That is, a group of genes including: SSBP1, IFI6 DDT, IFI27, C11orf92, NFKBIA, TNXB, NEAT1 and TFG were up-regulated while another group of genes consisting of: LAMB2, XRCC6, MEF2C, RBM5, FOXP1, NUDCP2, LGALS3, TMEM185A, and C1S were down-regulated in most patients. Survival analysis revealed that the up-regulated genes such as DDAH2, RNase K and TCEAL2 might be associated with a poor prognosis. Furthermore, the prognosis of patients with chemo-resistance was predicted to be very poor when genes such as RNase K, FOXP1, LAMB2 and MRVI1 were up-regulated.CONCLUSION:
The DEGs in patients with stage III serous ovarian cancer were successfully and reliably identified by the ACP-based RT PCR technique. The DEGs identified in this study might help predict the prognosis of patients with stage III serous ovarian cancer as well as suggest targets for the development of new treatment regimens.Related: Ovarian Cancer
Oh JJ, Taschereau EO, Koegel AK, et al.RBM5/H37 tumor suppressor, located at the lung cancer hot spot 3p21.3, alters expression of genes involved in metastasis.
Lung Cancer. 2010; 70(3):253-62 [PubMed
] Related Publications
The RBM5/H37 gene is located at the most 'sought-after' tumor suppressor locus in lung cancer, 3p21.3. This region of most frequent chromosomal deletion found at the earliest stage in lung cancer development houses 19 genes, many of which may act together as a 'tumor suppressor group', representing one of the most promising opportunities for development of new diagnostics/prognostics and therapeutics for lung cancer as well as for many other types of cancers. For the past decade, we have demonstrated tumor suppressor function of RBM5 in vitro and in vivo involving cell cycle arrest and apoptosis, as well as loss of RBM5 mRNA and protein expression in primary lung tumors. Here we report our latest data suggesting that RBM5 may regulate inhibition of metastasis in lung cancer. We performed cDNA microarray to identify global gene expression changes caused by RBM5 gene knockdown. In order to identify "consensus" pathways consistently deregulated by RBM5 loss irrespective of genetic background, the experiments were repeated in three different lung cancer cell lines of varying RBM5 expression levels, a normal lung epithelial cell line, and a normal breast epithelial cell line. Both Gene Set Enrichment Analysis (GSEA) and individual gene analysis identified consistent, statistically significant gene expression changes common to all five cell pairs examined. Genes involved in the functions of cell adhesion, migration and motility, known to be important in the metastatic process, were upregulated with RBM5-knockdown. These genes include Rac1, β-catenin, collagen, laminin and the overall gene set of the gene ontology group "proteinaceous extracellular matrix". Among these, we have focused on Rac1 and β-catenin which play essential roles in cell movement downstream of Wnt signaling. We have confirmed increased protein expression of β-catenin and increased protein activation of Rac1 with RBM5-knockdown. In addition, we found that RBM5 protein expression loss in primary lung tumors is correlated with increased lymph node metastasis in a small number of lung cancer patients. These data are corroborated by an independent report showing RBM5 as part of a 17-gene signature of metastasis in primary solid tumors. Taken together, the accumulated evidence suggests that RBM5 expression loss may increase the metastatic potential of tumors. Further study is warranted to evaluate the potential clinical utility of RBM5 in lung cancer diagnostics, prognostics and therapeutics.Related: Breast Cancer Chromosome 3 Lung Cancer Signal Transduction CTNNB1 gene
Sutherland LC, Wang K, Robinson AGRBM5 as a putative tumor suppressor gene for lung cancer.
J Thorac Oncol. 2010; 5(3):294-8 [PubMed
] Related Publications
RBM5 is one member of a group of structurally related genes that includes RBM6 and RBM10. RBM10 maps to Xp11.23, and one allele is inactivated as a result of X chromosome inactivation. Both RBM5 and RBM6 map to 3p21.3, a tumor suppressor region that experiences loss of heterozygosity in the majority of lung cancers. Overexpression of RBM5, which encodes an RNA-binding protein involved in the regulation of alternative splicing and retards ascites associated tumor growth in immunocompromised mice, a phenomenon that may be related to an associated ability to modulate apoptosis. As part of our quest to gain a better understanding of how the proapoptotic activity of RBM5 might contribute to tumor suppressor function, we reviewed all the literature relating to RBM5 expression, with a focus on lung cancer. On the basis of the existing data, we suggest that-to more thoroughly assess the potential involvement of RBM5 as a lung cancer regulatory protein-more research is required regarding (a) the expression of not only full-length RBM5 but all of the alternate variants associated with the locus, in relation to histologic subtype and smoking history, and (b) the mutation status of various genes within the transforming growth factor-alpha signaling pathway, which may function to either directly or indirectly regulate RBM5 activity in RBM5-retaining lung cancers.Related: Lung Cancer
Similar to many genes involved in programmed cell death (PCD), the caspase 2 (casp-2) gene generates both proapoptotic and antiapoptotic isoforms by alternative splicing. Using a yeast RNA-protein interaction assay, we identified RBM5 (also known as LUCA-15) as a protein that binds to casp-2 pre-mRNA. In both transfected cells and in vitro splicing assay, RBM5 enhances the formation of proapoptotic Casp-2L. RBM5 binds to a U/C-rich sequence immediately upstream of the previously identified In100 splicing repressor element. Our mutagenesis experiments demonstrate that RBM5 binding to this intronic sequence regulates the ratio of proapoptotic/antiapoptotic casp-2 splicing isoforms, suggesting that casp-2 splicing regulation by RBM5 may contribute to its tumor suppressor activity. Our work has uncovered a player in casp-2 alternative splicing regulation and revealed a link between the alternative splicing regulator and the candidate tumor suppressor gene. Together with previous studies, our work suggests that splicing control of cell death genes may be an important aspect in tumorigenesis. Enhancing the expression or activities of splicing regulators that promote the production of proapoptotic splicing isoforms might provide a therapeutic approach to cancer.Related: Cancer Prevention and Risk Reduction
Oh JJ, Boctor BN, Jimenez CA, et al.Promoter methylation study of the H37/RBM5 tumor suppressor gene from the 3p21.3 human lung cancer tumor suppressor locus.
Hum Genet. 2008; 123(1):55-64 [PubMed
] Related Publications
Loss of heterozygosity (LOH) at chromosome 3p21.3 is one of the most prevalent genetic disturbances occurring at the earliest stage of tumor development for a wide variety of human cancers, culminated in lung cancer. The 19 genes residing at 3p21.3 have been vigorously characterized for tumor suppressor activity and gene inactivation mechanism because of their potentially significant merits of clinical applications. Many of these 19 genes have been shown to manifest various growth inhibitory properties, however none of them are inactivated by coding mutations in their remaining allele as in the Knudson's two- hits hypothesis. Thus far the most prevailing, alternative gene inactivation mechanism known for the 3p21.3 TSGs is epigenetic silencing by promoter hypermethylation. Previously, we have focused our investigation on one of the 19 genes at 3p21.3, H37/RBM5, and demonstrated its tumor suppressor activity both in vitro and in vivo as well as its mRNA/protein expression loss from the remaining allele in a majority of the primary lung tumors examined. The current study tested our hypothesis that the H37 inactivation in primary lung tumors may, as seen in most of the other 3p21.3 TSGs, be due to hypermethylation in its promoter CpG islands. Contrary to this most plausible postulation, however, we found no evidence of epigenetic gene silencing for the H37 TSG. Here we suggest some of the possible, further- alternative means of the H37 gene expression loss in tumor, including defects in transcription and post-transcriptional/translational modifications as well as mechanisms related to haploinsufficiency.Related: Non-Small Cell Lung Cancer Chromosome 3 Lung Cancer
Oh JJ, Koegel AK, Phan DT, et al.The two single nucleotide polymorphisms in the H37/RBM5 tumour suppressor gene at 3p21.3 correlated with different subtypes of non-small cell lung cancers.
Lung Cancer. 2007; 58(1):7-14 [PubMed
] Free Access to Full Article Related Publications
Allele loss and genetic alteration in chromosome 3p, particularly in 3p21.3 region, are the most frequent and the earliest genomic abnormalities found in lung cancer. Multiple 3p21.3 genes exhibit various degrees of tumour suppression activity suggesting that 3p21.3 genes may function as an integrated tumour suppressor region through their diverse biological activities. We have previously demonstrated growth inhibitory effects and tumour suppression mechanism of the H37/RBM5 gene which is one of the 19 genes residing in the 370kb minimal overlap region at 3p21.3. In the current study, in an attempt to find, if any, mutations in the H37 coding region in lung cancer cells, we compared nucleotide sequences of the entire H37 gene in tumour versus adjacent normal tissues from 17 non-small cell lung cancer (NSCLC) patients. No mutations were detected; instead, we found the two silent single nucleotide polymorphisms (SNPs), C1138T and C2185T, within the coding region of the H37 gene. In addition, we found that specific allele types at these SNP positions are correlated with different histological subtypes of NSCLC; tumours containing heterozygous alleles (C+T) at these SNP positions are more likely to be associated with adenocarcinoma (AC), whereas, homozygous alleles (either C or T) are associated with squamous cell carcinoma (SCC) (p=0.0098). We postulate that, these two silent polymorphisms may be in linkage disequilibrium (LD) with a disease causative allele in the 3p21.3 tumour suppressor region which is packed with a large number of important genes affecting lung cancer development. In addition, because of prevalent loss of heterozygosity (LOH) detected at 3p21.3 which precedes lung cancer initiation, these SNPs may be developed into a marker screening for the high risk individuals.Related: Non-Small Cell Lung Cancer Chromosome 3 Lung Cancer
The candidate tumour-suppressor gene, LUCA-15/RBM5/H37, maps to the lung cancer tumour-suppressor locus 3p21.3. The LUCA-15 gene locus encodes at least four alternatively spliced transcripts that have been shown to function as regulators of apoptosis, a fact which may have major significance in tumour regulation. This review highlights recent evidence that further implicates the LUCA-15 locus in the control of apoptosis and cell proliferation, and focuses on the observations that confirm the tumour-suppressor activity of this gene.Related: Apoptosis Lung Cancer
Rintala-Maki ND, Goard CA, Langdon CE, et al.Expression of RBM5-related factors in primary breast tissue.
J Cell Biochem. 2007; 100(6):1440-58 [PubMed
] Related Publications
The aim of this study was to examine the expression of the RBM5 tumor suppressor, in relation to RBM6 and RBM10, to obtain a better understanding of the potential role played by these RBM5-related factors in the regulation of RBM5 tumor-suppressor activity. Paired non-tumor and tumor samples were obtained from 73 breast cancer patients. RNA and protein expression were examined by semi-quantitative reverse transcription-polymerase chain reaction and immunoblot, respectively. Data were analyzed using various statistical methods to test for correlations amongst the RBM5-related factors, and between the factors and various pathological parameters. Most notably, RBM5, RBM10v1, and HER2 protein expression levels were elevated in tumor tissue (P < 0.0001). RBM5 and RBM10v1 protein expression were significantly positively correlated (P < 0.001), as were RBM5 and HER2 protein expression (P < 0.01), in both non-tumor and tumor tissue, whereas RBM10v1 and HER2 protein expression were only marginally correlated, in non-tumor tissue (P < 0.05). Interestingly, RBM5 and RBM10v1 protein expression were both deregulated in relation to RNA expression in tumor tissue. RBM10v2 and RBM6 RNA were highly significantly positively correlated in relation to various factors relating to poor prognosis (P < 0.0001). To our knowledge, this study is the first to examine RBM5 expression at both the RNA and protein level in primary breast tumor tissue, and the first to examine expression of all RBM5-related factors in a comprehensive manner. The results provide a graphic illustration that RBM5-related factors are significantly differentially expressed in breast cancer, and suggest complex inter-related regulatory networks involving alternative splicing, oncogenic expression, and tissue-specific function.Related: Breast Cancer
Masdeu C, Faure H, Coulombe J, et al.Identification and characterization of Hedgehog modulator properties after functional coupling of Smoothened to G15.
Biochem Biophys Res Commun. 2006; 349(2):471-9 [PubMed
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The seven-transmembrane receptor Smoothened (Smo) transduces the signal initiated by Hedgehog (Hh) morphogen binding to the receptor Patched (Ptc). We have reinvestigated the pharmacological properties of reference molecules acting on the Hh pathway using various Hh responses and a novel functional assay based on the coexpression of Smo with the alpha subunit of the G15 protein in HEK293 cells. The measurement of inositol phosphate (IP) accumulation shows that Smo has constitutive activity, a response blocked by Ptc which indicates a functional Hh receptor complex. Interestingly, the antagonists cyclopamine, Cur61414, and SANT-1 display inverse agonist properties and the agonist SAG has no effect at the Smo-induced IP response, but converts Ptc-mediated inactive forms of Smo into active ones. An oncogenic Smo mutant does not mediate an increase in IP response, presumably reflecting its inability to reach the cell membrane. These studies identify novel properties of molecules displaying potential interest in the treatment of various cancers and brain diseases, and demonstrate that Smo is capable of signaling through G15.Related: Cancer Prevention and Risk Reduction Signal Transduction
Oh JJ, Razfar A, Delgado I, et al.3p21.3 tumor suppressor gene H37/Luca15/RBM5 inhibits growth of human lung cancer cells through cell cycle arrest and apoptosis.
Cancer Res. 2006; 66(7):3419-27 [PubMed
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Deletion at chromosome 3p21.3 is the earliest and the most frequently observed genetic alteration in lung cancer, suggesting that the region contains tumor suppressor gene(s) (TSG). Identification of those genes may lead to the development both of biomarkers to identify high-risk individuals and novel therapeutics. Previously, we cloned the H37/Luca15/RBM5 gene from 3p21.3 and showed its TSG characteristics. To investigate the physiologic function of H37 in the lung and its mechanism of tumor suppression, we have stably transfected H37 into A549 non-small cell lung cancer cells. A549/H37 cells show significant growth inhibition compared with the vector controls by in vitro and in vivo cell proliferation assays. Using this lung cancer cell model, we have found that the molecular mechanism of H37 tumor suppression involves both cell cycle (G(1)) arrest and apoptosis. To further define H37's function in cell cycle/apoptotic pathways, we investigated differential expression profiles of various cell cycle and apoptosis regulatory proteins using Western blot analysis. Both cyclin A and phophorylated RB levels were decreased in H37-transfected cells, whereas expression of Bax protein was increased. Mitochondrial regulation of apoptosis further downstream of Bax was investigated, showing change in the mitochondrial membrane potential, cytochrome c release into the cytosol, and enhanced caspase-9 and caspase-3 activities. We also report that H37 may mediate apoptosis in a p53-independent manner, and Bax knockdown by small interfering RNA suggests Bax plays a functional role downstream of H37. Lastly, we proposed a tumor suppression model of H37 as a post-transcriptional regulator for cell cycle/apoptotic-related proteins.Related: Apoptosis Non-Small Cell Lung Cancer Chromosome 3 Lung Cancer Mitochondrial Mutations in Cancer TP53
Rintala-Maki ND, Abrasonis V, Burd M, Sutherland LCGenetic instability of RBM5/LUCA-15/H37 in MCF-7 breast carcinoma sublines may affect susceptibility to apoptosis.
Cell Biochem Funct. 2004 Sep-Oct; 22(5):307-13 [PubMed
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The MCF-7 human breast carcinoma cell line is widely used as a model system by breast cancer researchers and cell biologists investigating apoptosis. Since its establishment 30 years ago, from a patient with metastatic breast cancer, the original MCF-7 cell population has undergone genetic drift to such an extent that numerous genetically diverse sublines now exist. For instance, it has been reported that MCF-7 cells have lost the region 3p21.3, to which the apoptosis regulatory protein and putative tumour suppressor LUCA-15 (also called RBM5 and H37) maps; however, LUCA-15 has been cloned from MCF-7 cells, and LUCA-15 expression analyses have been conducted using MCF-7 cells. To address this discrepancy, we characterized three MCF-7 sublines by Western blot, RT-PCR and finally genomic PCR analysis, and determined that one of the three had lost the LUCA-15 gene. Interestingly, loss of LUCA-15 was positively correlated with decreased susceptibility to the death-inducing ligand TNF-alpha. Subsequent overexpression of exogenous LUCA-15 was shown to enhance TNF-alpha-mediated apoptosis, suggesting that LUCA-15 may play a role in regulating the susceptibility of breast cancer cells to drug-induced apoptosis. These results not only reinforce the necessity of MCF-7 subline characterization, but provide the first evidence of an apoptotic modulatory role for LUCA-15 in a non-T cell line.Related: Apoptosis Breast Cancer TNF
Oh JJ, West AR, Fishbein MC, Slamon DJA candidate tumor suppressor gene, H37, from the human lung cancer tumor suppressor locus 3p21.3.
Cancer Res. 2002; 62(11):3207-13 [PubMed
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Edamatsu H, Kaziro Y, Itoh HLUCA15, a putative tumour suppressor gene encoding an RNA-binding nuclear protein, is down-regulated in ras-transformed Rat-1 cells.
Genes Cells. 2000; 5(10):849-58 [PubMed
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The proliferation of mammalian cells is controlled by various intracellular mitogenic signalling pathways. In the intracellular pathways, Ras is involved in the activation of proto-oncogenes such as an immediate early gene c-fos. The somatic mutations of ras genes that elicit the constitutive activation of Ras have been found in tumours. Although these findings suggest that the constitutive activation of Ras-mediated pathways alters the expression of a set of genes involving tumorigenesis, these genes have not yet fully been studied.RESULTS:
To study the up- or down-regulated genes in ras-transformed cells, we analysed Rat-1 transfectants expressing Ras(G12V) mutant protein in response to isopropyl-1-beta-thio-D-galactoside using a differential display. We found that the mRNA level of rat homologue of LUCA15, which has been cloned initially as a putative tumour suppressor gene mapped on human chromosome 3, was down-regulated by the expression of Ras(G12V). Epitope-tagged LUCA15 protein was localized in nuclei and had the ability to bind poly(G) RNA homopolymers in vitro. Moreover, ectopic expression of LUCA15 in human fibrosarcoma HT1080 cells suppressed the cell growth.CONCLUSION:
These results demonstrate that LUCA15 is one of the down-regulated genes in ras-transformed cells, and suggests that LUCA15 may function as a negative regulator of cell proliferation by the alteration of its mRNA level.Related: Chromosome 3
Timmer T, Terpstra P, van den Berg A, et al.An evolutionary rearrangement of the Xp11.3-11.23 region in 3p21.3, a region frequently deleted in a variety of cancers.
Genomics. 1999; 60(2):238-40 [PubMed
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Drabkin HA, West JD, Hotfilder M, et al.DEF-3(g16/NY-LU-12), an RNA binding protein from the 3p21.3 homozygous deletion region in SCLC.
Oncogene. 1999; 18(16):2589-97 [PubMed
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DEF-3(g16/NY-LU-12) encodes a novel RNA binding protein isolated by positional cloning from an SCLC homozygous deletion region in 3p21.3 and, in parallel, as a differentially expressed gene during myelopoiesis from FDCPmix-A4 cells. DEF-3(g16/NY-LU-12) is ubiquitously expressed during mouse embryogenesis and in adult organs while human hematopoietic tissues showed differential expression. The mouse and human proteins are highly conserved containing two RNA recognition motifs (RRMs) and other domains associated with RNA binding and protein-protein interactions. A database search identified related proteins in human, rat, C. elegans and S. pombe including the 3p21.3 co-deleted gene, LUCA15. Recombinant proteins containing the RRMs of DEF-3(g16/NY-LU-12) and LUCA15 specifically bound poly(G) RNA homopolymers in vitro. These RRMs also show similarity to those of the Hu protein family. Since anti-Hu RRM domain antibodies are associated with an anti-tumor effect and paraneoplastic encephalomyelitis, we tested sera from Hu syndrome patients with the RRMs of DEF-3(g16/NY-LU-12) and LUCA15. These were non-reactive. Thus, DEF-3(g16/NY-LU-12) and LUCA15 represent members of a novel family of RNA binding proteins with similar expression patterns and in vitro RNA binding characteristics. They are co-deleted in some lung cancers and immunologically distinct from the Hu proteins.Related: Chromosome 3 Lung Cancer
Timmer T, Terpstra P, van den Berg A, et al.A comparison of genomic structures and expression patterns of two closely related flanking genes in a critical lung cancer region at 3p21.3.
Eur J Hum Genet. 1999 May-Jun; 7(4):478-86 [PubMed
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In the search for a tumour suppressor gene in the 3p21.3 region we isolated two genes, RBM5 and RBM6. Gene RBM5 maps to the region which is homozygously deleted in the small cell lung cancer cell line GLC20; RBM6 crosses the telomeric breakpoint of this deletion. Sequence comparison revealed that at the amino acid level both genes show 30% identity. They contain two zinc finger motifs, a bipartite nuclear signal and two RNA binding motifs, suggesting that the proteins for which RBM5 and RBM6 are coding have a DNA/RNA binding function and are located in the nucleus. Northern and Southern analysis did not reveal any abnormalities. By SSCP analysis of 16 lung cancer cell lines we found only in RBM5 a single presumably neutral mutation. By RT-PCR we demonstrated the existence of two alternative splice variants of RBM6, one including and one excluding exon 5, in both normal lung tissue and lung cancer cell lines. Exclusion of exon 5 results in a frameshift which would cause a truncated protein of 520 amino acids instead of 1123 amino acids. In normal lung tissue, the relative amount of the shorter transcript was much greater than that in the lung tumour cell lines, which raises the question whether some tumour suppressor function may be attributed to the derived shorter protein.Related: Chromosome 3 Lung Cancer