Project description:Deciphering the molecular mechanisms involved in breast tumorigenesis has been the subject of extensive research in the last years; yet unpredictable response and development of resistance to adjuvant therapies remain major questions in the management of breast cancer patients. The power of miR expression signatures has emerged recently from several studies. Normal and breast tumor tissues can be discriminated by a miR signature as reported by Iorio et al (Iorio et al, 2005). Recent findings have also linked deregulated miR expression to breast cancer metastasis (Adorno et al, 2009; Huang et al, 2008; Tavazoie et al, 2008). Moreover, microRNAs are considering as a powerful tool in diagnosis and prognosis of breast cancer. In our study, we measured microRNA expression profiles from 64 primary breast cancer patients, comprising 56 matched tumor and adjacent peritumoral breast tissues, 5 tumor and 3 peritumor unmatched tissues. Our aim was to identify new microRNAs involved in the process of neoplastic transformation. The microarray data analysis identified, in every subgroup of breast cancers analyzed, a specific subset of microRNAs that were differentially expressed in tumor compared to peritumoral tissues. Among these miRs, we identified two (miR-10b* and miR-139-5p) that were down-regulated and three (miR-425, miR-454 and miR-301a) that were up-regulated for all three subtypes. We further show that microRNA-10b* is a master regulator of breast cancer cell proliferation. Two canonical CpG islands (5kb) upstream from the precursor sequence are hypermethylated in breast cancer tissues analyzed. Ectopic delivery of synthetic microRNA-10b* in breast cancer cell lines or into xenograft mouse breast tumors inhibits cell proliferation and impairs tumor growth in vivo, respectively. We identified and validated in vitro and in vivo three novel target mRNAs of miR-10b*, BUB1, PLK1 and CCNA2 genes, which play a remarkable role in cell cycle regulation and whose high expression in breast cancer patients reduced disease free survival, relapse free survival and metastasis free survival when compared to low expressors. This also suggests that restoration of microRNA-10b* expression might bear therapeutic promise. In exploring the potential involvement of miRs in breast tumorigenesis, we profiled the miRs expression of 64 primary breast cancer patients, comprising 56 matched tumor and adjacent peritumoral breast tissues, 5 tumor and 3 peritumor unmatched tissues, using the Agilent microarray platform. For 14 samples technical replicate were also performed.

Project description:Deciphering the molecular mechanisms involved in breast tumorigenesis has been the subject of extensive research in the last years; yet unpredictable response and development of resistance to adjuvant therapies remain major questions in the management of breast cancer patients. The power of miR expression signatures has emerged recently from several studies. Normal and breast tumor tissues can be discriminated by a miR signature as reported by Iorio et al (Iorio et al, 2005). Recent findings have also linked deregulated miR expression to breast cancer metastasis (Adorno et al, 2009; Huang et al, 2008; Tavazoie et al, 2008). Moreover, microRNAs are considering as a powerful tool in diagnosis and prognosis of breast cancer. In our study, we measured microRNA expression profiles from 64 primary breast cancer patients, comprising 56 matched tumor and adjacent peritumoral breast tissues, 5 tumor and 3 peritumor unmatched tissues. Our aim was to identify new microRNAs involved in the process of neoplastic transformation. The microarray data analysis identified, in every subgroup of breast cancers analyzed, a specific subset of microRNAs that were differentially expressed in tumor compared to peritumoral tissues. Among these miRs, we identified two (miR-10b* and miR-139-5p) that were down-regulated and three (miR-425, miR-454 and miR-301a) that were up-regulated for all three subtypes. We further show that microRNA-10b* is a master regulator of breast cancer cell proliferation. Two canonical CpG islands (5kb) upstream from the precursor sequence are hypermethylated in breast cancer tissues analyzed. Ectopic delivery of synthetic microRNA-10b* in breast cancer cell lines or into xenograft mouse breast tumors inhibits cell proliferation and impairs tumor growth in vivo, respectively. We identified and validated in vitro and in vivo three novel target mRNAs of miR-10b*, BUB1, PLK1 and CCNA2 genes, which play a remarkable role in cell cycle regulation and whose high expression in breast cancer patients reduced disease free survival, relapse free survival and metastasis free survival when compared to low expressors. This also suggests that restoration of microRNA-10b* expression might bear therapeutic promise.

Project description:Deciphering the molecular mechanisms involved in breast tumorigenesis has been the subject of extensive research in the last years; yet unpredictable response and development of resistance to adjuvant therapies remain major questions in the management of breast cancer patients. The power of miR expression signatures has emerged recently from several studies. Normal and breast tumor tissues can be discriminated by a miR signature as reported by Iorio et al (Iorio et al, 2005). Recent findings have also linked deregulated miR expression to breast cancer metastasis (Adorno et al, 2009; Huang et al, 2008; Tavazoie et al, 2008). Moreover, microRNAs are considering as a powerful tool in diagnosis and prognosis of breast cancer. In our study, we measured microRNA expression profiles from 64 primary breast cancer patients, comprising 56 matched tumor and adjacent peritumoral breast tissues, 5 tumor and 3 peritumor unmatched tissues. Our aim was to identify new microRNAs involved in the process of neoplastic transformation. The microarray data analysis identified, in every subgroup of breast cancers analyzed, a specific subset of microRNAs that were differentially expressed in tumor compared to peritumoral tissues. Among these miRs, we identified two (miR-10b* and miR-139-5p) that were down-regulated and three (miR-425, miR-454 and miR-301a) that were up-regulated for all three subtypes. We further show that microRNA-10b* is a master regulator of breast cancer cell proliferation. Two canonical CpG islands (5kb) upstream from the precursor sequence are hypermethylated in breast cancer tissues analyzed. Ectopic delivery of synthetic microRNA-10b* in breast cancer cell lines or into xenograft mouse breast tumors inhibits cell proliferation and impairs tumor growth in vivo, respectively. We identified and validated in vitro and in vivo three novel target mRNAs of miR-10b*, BUB1, PLK1 and CCNA2 genes, which play a remarkable role in cell cycle regulation and whose high expression in breast cancer patients reduced disease free survival, relapse free survival and metastasis free survival when compared to low expressors. This also suggests that restoration of microRNA-10b* expression might bear therapeutic promise. In exploring the potential involvement of miRs in breast tumorigenesis, we profiled the miRs expression of 64 primary breast cancer patients, comprising 56 matched tumor and adjacent peritumoral breast tissues, 5 tumor and 3 peritumor unmatched tissues, using the Agilent microarray platform. For 14 samples technical replicate were also performed.

Project description:Breast cancer is the leading cause of cancer-related death in women worldwide. Aberrant expression levels of miR-10b-5p in breast cancer has been reported while the molecular mechanism of miR-10b-5p in tumorigenesis remains elusive. Therefore, this study was aimed to investigate the role of miR-10b-5p in breast cancer and the network of its target genes using bioinformatics analysis. In this study, the expression profiles and prognostic value of miR-10b-5p in breast cancer were analyzed from public databases. Association between miR-10b-5p and clinicopathological parameters were analyzed by non-parametric test. Moreover, the optimal target genes of miR-10b-5p were obtained and their expression patterns were examined using starBase and HPA database. Additionally, the role of these target genes in cancer development were explored via Cancer Hallmarks Analytics Tool (CHAT). The protein-protein interaction (PPI) networks were constructed to further investigate the interactive relationships among these genes. Furthermore, GO, KEGG pathway and Reactome pathway analyses were carried out to decipher functions of these target genes. Results demonstrated that miR-10b-5p was down-regulated in breast cancer and low expression of miR-10b-5p was significantly correlated to worse outcome. Five genes, BIRC5, E2F2, KIF2C, FOXM1, and MCM5, were considered as potential key target genes of miR-10b-5p. As expected, higher expression levels of these genes were observed in breast cancer tissues than in normal tissues. Moreover, analysis from CHAT revealed that these genes were mainly involved in sustaining proliferative signaling in cancer development. In addition, PPI networks analysis revealed strong interactions between target genes. GO, KEGG, and Reactome pathway analysis suggested that these target genes of miR-10b-5p in breast cancer were significantly involved in cell cycle. Predicted target genes were further validated by qRT-PCR analysis in human breast cancer cell line MDA-MB-231 transfected with miR-10b mimic or antisense inhibitors. Taken together, our data suggest that miR-10b-5p functions to impede breast carcinoma progression via regulation of its key target genes and hopefully serves as a potential diagnostic and prognostic marker for breast cancer.

Project description:BackgroundFamilial triple-negative breast cancers are often linked to mutations in the BRCA1 tumor suppressor gene. In sporadic triple-negative breast cancers BRCA1 is frequently inactivated at the transcriptional level, and it has been reported that this inactivation may be brought about by promoter methylation. More recently, it was found that BRCA1 may also be regulated at the post-transcriptional level by miRNAs. Here, we explored the expression of putative BRCA1-regulating miRNAs in sporadic human triple-negative breast cancer cells.MethodsNine sporadic human breast cancer-derived cell lines and one benign breast epithelium-derived cell line were assessed for their hormone receptor, growth factor receptor and cytokeratin status by immunocytochemistry. The expression of 5 selected miRNAs predicted to target BRCA1 was assessed using qRT-PCR in the 10 cell lines. In addition, expression profiles of 84 known breast cancer-associated miRNAs were established in these 10 cell lines using PCR Array and qRT-PCR, respectively. The putative role of pre-selected candidate miRNAs in breast cancer development was assessed through exogenous expression of these miRNAs and their anti-miRNAs ('antagomirs') in MDA-MB-231 and MCF7 breast cancer-derived cells.ResultsBased on our expression profiling results, four candidate miRNAs (miR-10b, miR-26a, miR-146a and miR-153) were selected as being potentially involved in triple-negative breast cancer development. Exogenous expression assays revealed that miR-10b and miR-26a, but not miR-146a, can down-regulate the expression of BRCA1 in both triple-negative MDA-MB-231 and luminal epithelial MCF7 breast cancer-derived cells, whereas miR-153 could down-regulate BRCA1 expression only in MCF7 cells. In silico analysis of The Cancer Genome Atlas (TCGA) data confirmed that miR-146a is significantly higher expressed in triple-negative breast tumors compared to other (non triple-negative) breast tumors.ConclusionOur work provides evidence for the involvement of specific miRNAs in triple-negative breast cancer development through regulating BRCA1 expression.

Project description:IntroductionExosomes are 30-100 nm membrane vesicles of endocytic origin, mediating diverse biological functions including tumor cell invasion, cell-cell communication and antigen presentation through transfer of proteins, mRNAs and microRNAs. Recent evidence suggests that microRNAs can be released through ceramide-dependent secretory machinery regulated by neutral sphingomyelinase 2 (nSMase2) enzyme encoded by the smpd3 gene that triggers exosome secretion. However, whether exosome-mediated microRNA transfer plays any role in cell invasion remains poorly understood. Thus, the aim of this study was to identify the exosomal microRNAs involved in breast cancer invasion.MethodsThe expression level of endogenous and exosomal miRNAs were examined by real time PCR and the expression level of target proteins were detected by western blot. Scanning electron and confocal microscopy were used to characterize exosomes and to study its uptake and transfer. Luciferase reporter plasmids and its mutant were used to confirm direct targeting. Furthermore, the functional significance of exosomal miR-10b was estimated by invasion assay.ResultsIn this study, we demonstrate that microRNA carrying exosomes can be transferred among different cell lines through direct uptake. miR-10b is highly expressed in metastatic breast cancer MDA-MB-231 cells as compared to non-metastatic breast cancer cells or non-malignant breast cells; it is actively secreted into medium via exosomes. In particular, nSMase2 or ceramide promotes the exosome-mediated miR-10b secretion whereas ceramide inhibitor suppresses this secretion. Moreover, upon uptake, miR-10b can suppress the protein level of its target genes such as HOXD10 and KLF4, indicating its functional significance. Finally, treatment with exosomes derived from MDA-MB-231 cells could induce the invasion ability of non-malignant HMLE cells.ConclusionTogether, our results suggest that a set of specific microRNAs may play an important role in modulating tumor microenvironment through exosomes. Thus, a better understanding of this process may aid in the development of novel therapeutic agents.

Dataset Information

MiR-10b*, a master inhibitor of the cell cycle, is down-regulated in human breast tumours.

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miR-10b*, a master inhibitor of the cell cycle, is down-regulated in human breast tumours.

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