Apoptosis gene signature of Survivin and its splice variant expression in breast carcinoma
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ABSTRACT: Background: Survivin was described as strongly expressed in human cancer. To date, little is known about the association between Survivin splice variants and the other apoptosis-related genes. In this study, we analyzed the apoptosis gene signature of Survivin and its variant expression in breast cancer. Methods: Expression of the 5 transcripts was measured by RT-PCR in 135 breast carcinomas. Human Apoptosis Gene Arrays were used to screen the genes that could be associated with Survivin variants. Cox survival analysis was analyzed according to the breast cancer patient outcome. Results: Significant associations between Survivin transcript and the apoptotic gene array were found. Interestingly, Survivin-3B variant showed major inverse correlations with the pro-apoptotic gene array. Overexpression of Survivin-3B strongly inhibits 5-fluorouracil/epirubicin/Cyclophosphamide induced-apoptosis in breast tumor cell lines. In breast carcinomas, uni- and multivariate analysis showed patients with high level of survivin-3B expression had a shorter overall (p=0.030 and p=0.042, respectively) and disease-free (p=0.024 and p=0.009) survival. Conclusion: Our data indicate Survivin-3B could have an anti-apoptotic activity and its expression level might be used as a prognostic marker in breast carcinoma. The expression of 96 apoptosis genes and was analyzed in 41 breast carcinomas and 1 pool of normal mammary tissues. In parallel, every survivin isoform expression was quantified by real-time quantitative PCR. Data obtained with the macro-array were correlated with survivin isoform levels detected by RT-PCR.
Project description:Background: Survivin was described as strongly expressed in human cancer. To date, little is known about the association between Survivin splice variants and the other apoptosis-related genes. In this study, we analyzed the apoptosis gene signature of Survivin and its variant expression in breast cancer. Methods: Expression of the 5 transcripts was measured by RT-PCR in 135 breast carcinomas. Human Apoptosis Gene Arrays were used to screen the genes that could be associated with Survivin variants. Cox survival analysis was analyzed according to the breast cancer patient outcome. Results: Significant associations between Survivin transcript and the apoptotic gene array were found. Interestingly, Survivin-3B variant showed major inverse correlations with the pro-apoptotic gene array. Overexpression of Survivin-3B strongly inhibits 5-fluorouracil/epirubicin/Cyclophosphamide induced-apoptosis in breast tumor cell lines. In breast carcinomas, uni- and multivariate analysis showed patients with high level of survivin-3B expression had a shorter overall (p=0.030 and p=0.042, respectively) and disease-free (p=0.024 and p=0.009) survival. Conclusion: Our data indicate Survivin-3B could have an anti-apoptotic activity and its expression level might be used as a prognostic marker in breast carcinoma.
Project description:Targeting “oncogene addiction” is a promising strategy for anti-cancer therapy. Here, we report a potent inhibition of crucial oncogenes by p53 upon reactivation with small molecule RITA in vitro and in vivo. RITA-activated p53 unleashes transcriptional repression of anti-apoptotic proteins Mcl-1, Bcl-2, MAP4, and survivin, blocks Akt pathway on several levels and downregulates c-Myc, cyclin E and B-catenin. p53 ablates c-Myc expression via several mechanisms at transcriptional and posttranscriptional level. We show that transrepression of oncogenes correlated with higher level of p53 bound to chromatin-bound p53 than transactivation of pro-apoptotic targets. Inhibition of oncogenes by p53 reduces the cell’s ability to buffer pro-apoptotic signals and elicits robust apoptosis. Our study highlights the role of transcriptional repression for p53-mediated tumor suppression. Experiment Overall Design: Breast carcinoma cell-line MCF7 was treated with the small-molecule p53 activator RITA for 2h, 8h, 16h and 24h.
Project description:There is increasing evidence that microRNA and transcription factors interact in an instructive fashion in normal and malignant hematopoiesis. We explored the impact of TEL-AML1 (ETV6-RUNX1), the most common fusion protein in childhood leukemia, on miRNA expression and the leukemic phenotype. Using RNA interference, miRNA expression arrays, and quantitative PCR, we identified miRNA-494 and miRNA-320a to be upregulated upon TEL-AML1 silencing independently of TEL expression. Chromatin immunoprecipitation analysis identified miRNA-494 as a direct miRNA target of the fusion protein TEL-AML1. Using bioinformatic analysis as well as functional luciferase experiments we demonstrate that survivin is a target of the two miRNAs. MiRNA-494 and -320a were introduced to the cells by transfection and survivin expression determined by western blot analysis. These miRNAs blocked survivin expression and resulted in apoptosis in a similar manner as TEL-AML1 silencing by itself; this silencing was also shown to be DICER-dependent. MiRNAs-494 and -320a are expressed at lower levels in TEL-AML1+ leukemias compared to immunophenotype-matched non-TEL-AML1 ALL subtypes, and within TEL-AML1+ leukemias their expression is correlated to survivin levels. In summary our data suggest that TEL-AML1 might exert its anti-apoptotic action at least in part by suppressing miRNA-494 and miRNA-320a, lowering their expression causing enhanced survivin expression. DNAs from REH cells were pulled down using ChIP antibodies to TEL and hybridized to microRNA promoter tiling arrays.
Project description:Jörg W. Stucki & Hans-Uwe Simon. Mathematical modeling of the regulation of caspase-3 activation and degradation. Journal of Theoretical Biology 234, 1 (2005).
Caspases are thought to be important players in the execution process of apoptosis. Inhibitors of apoptosis (IAPs) are able to block caspases and therefore apoptosis. The fact that a subgroup of the IAP family inhibits active caspases implies that not each caspase activation necessarily leads to apoptosis. In such a scenario, however, processed and enzymically active caspases should somehow be removed. Indeed, IAP–caspase complexes covalently bind ubiquitin, resulting in degradation by the 26S proteasome. Following release from mitochondria, IAP antagonists (e.g. second mitochondrial activator of caspases (Smac)) inactivate IAPs. Moreover, although pro-apoptotic factors such as irradiation or anti-cancer drugs may release Smac from mitochondria in tumor cells, high cytoplasmic survivin and ML-IAP levels might be able to neutralize it and, consequently, IAPs would further be able to bind activated caspases. Here, we propose a simple mathematical model, describing the molecular interactions between Smac deactivators, Smac, IAPs, and caspase-3, including the requirements for both induction and prevention of apoptosis, respectively. In addition, we predict a novel mechanism of caspase-3 degradation that might be particularly relevant in long-living cells.
Project description:The liver possesses remarkable regenerative capacity in response to injury. Upon partial hepatectomy (PHx), terminally differentiated hepatocytes in the remaining liver enter the cell cycle and restore the liver mass and function within weeks. However, liver regeneration is often impaired in livers with chronic diseases. Survivin, an inhibitor of apoptosis protein (IAP) and member of chromosome passenger complex (CPC), plays versatile roles in cell mitosis and apoptosis. We and others found that the expression of Survivin was highly increased in liver during PHx-induced liver regeneration, which indicated that Survivin played important roles in this process. However, the function of Survivin in liver regeneration remains largely undefined. Here, using mice with genetic deletion of Survivin, we found that during PHx-induced liver regeneration Survivin regulated both hepatocyte G1/S phase transition by inhibiting the expression of p21 and G2/M phase transition by regulating the localization of CPC. Moreover, restoration of Survivin expression in Survivin-deficient hepatocytes inhibited p21 expression and promote both hepatocyte G1/S and G2/M transition during PHx-induced liver regeneration.
Project description:Stem cells (SCs) and not progenitors (Ps) act as cells of origin of Basal Cell Carcinoma (BCC). The mechanisms promoting BCC formation in SCs or restricting tumour development in Ps are currently unknown. In this study, we transcriptionally profiled SCs and Ps and found that Survivin, a pleiotropic factor that promotes cell division and inhibits apoptosis was preferentially expressed in SCs. Using genetic gain and loss of function mouse models, we showed that Survivin deletion in oncogene-expressing SCs prevents BCC formation. Survivin overexpression renders Ps competent to BCC formation by promoting cell survival and division while preventing apoptosis and differentiation. We identified SGK1, as a key downstream factor of Survivin, and its inhibition prevents BCC formation. This study uncovers the role and mechanisms by which Survivin regulates the competence of SCs to initiate BCC formation promoting the survival of oncogene-expressing SCs and self-renewing division while restricting differentiation and apoptosis.
Project description:Stem cells (SCs) and not progenitors (Ps) act as cells of origin of Basal Cell Carcinoma (BCC). The mechanisms promoting BCC formation in SCs or restricting tumour development in Ps are currently unknown. In this study, we transcriptionally profiled SCs and Ps and found that Survivin, a pleiotropic factor that promotes cell division and inhibits apoptosis was preferentially expressed in SCs. Using genetic gain and loss of function mouse models, we showed that Survivin deletion in oncogene-expressing SCs prevents BCC formation. Survivin overexpression renders Ps competent to BCC formation by promoting cell survival and division while preventing apoptosis and differentiation. We identified SGK1, as a key downstream factor of Survivin, and its inhibition prevents BCC formation. This study uncovers the role and mechanisms by which Survivin regulates the competence of SCs to initiate BCC formation promoting the survival of oncogene-expressing SCs and self-renewing division while restricting differentiation and apoptosis.
Project description:There is increasing evidence that microRNA and transcription factors interact in an instructive fashion in normal and malignant hematopoiesis. We explored the impact of TEL-AML1 (ETV6-RUNX1), the most common fusion protein in childhood leukemia, on miRNA expression and the leukemic phenotype. Using RNA interference, miRNA expression arrays, and quantitative PCR, we identified miRNA-494 and miRNA-320a to be upregulated upon TEL-AML1 silencing independently of TEL expression. Chromatin immunoprecipitation analysis identified miRNA-494 as a direct miRNA target of the fusion protein TEL-AML1. Using bioinformatic analysis as well as functional luciferase experiments we demonstrate that survivin is a target of the two miRNAs. MiRNA-494 and -320a were introduced to the cells by transfection and survivin expression determined by western blot analysis. These miRNAs blocked survivin expression and resulted in apoptosis in a similar manner as TEL-AML1 silencing by itself; this silencing was also shown to be DICER-dependent. MiRNAs-494 and -320a are expressed at lower levels in TEL-AML1+ leukemias compared to immunophenotype-matched non-TEL-AML1 ALL subtypes, and within TEL-AML1+ leukemias their expression is correlated to survivin levels. In summary our data suggest that TEL-AML1 might exert its anti-apoptotic action at least in part by suppressing miRNA-494 and miRNA-320a, lowering their expression causing enhanced survivin expression.
Project description:Targeting “oncogene addiction” is a promising strategy for anti-cancer therapy. Here, we report a potent inhibition of crucial oncogenes by p53 upon reactivation with small molecule RITA in vitro and in vivo. RITA-activated p53 unleashes transcriptional repression of anti-apoptotic proteins Mcl-1, Bcl-2, MAP4, and survivin, blocks Akt pathway on several levels and downregulates c-Myc, cyclin E and B-catenin. p53 ablates c-Myc expression via several mechanisms at transcriptional and posttranscriptional level. We show that transrepression of oncogenes correlated with higher level of p53 bound to chromatin-bound p53 than transactivation of pro-apoptotic targets. Inhibition of oncogenes by p53 reduces the cell’s ability to buffer pro-apoptotic signals and elicits robust apoptosis. Our study highlights the role of transcriptional repression for p53-mediated tumor suppression. Keywords: time course