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:Purpose: There is a quest for novel non-invasive diagnostic markers for the detection of breast cancer. The goal of this study is to identify circulating microRNA signatures using a cohort of Asian Chinese breast cancer patients, and to compare microRNA profiles between tumour and serum samples. Experimental design: MicroRNAs from paired breast cancer tumours, normal tissue and serum samples derived from 32 patients were comprehensively profiled using microarrays (1300 microRNAs against tumour and normal tissues) or LNA RT-PCR panels (742 microRNAs against serum samples). Serum samples from healthy individuals (n=22) were also employed as normal controls. Significant serum microRNAs, identified by logistic regression, were validated in an independent set of serum samples from patients (n=82) and healthy controls (n=53). Results: The 20 most significant microRNAs differentially expressed in breast cancer tumours included miR-21, miR-10b, and miR-145, previously shown to be dysregulated in breast cancer. Interestingly, 16 of the 20 most significant microRNAs differentially expressed in serum samples were novel. MiR-1, miR-92a, miR-133a and miR-133b were identified as the most important diagnostic markers, and were successfully validated; receiver operating characteristic curves derived from combinations of these microRNAs exhibited areas under the curves of 0.944-0.946. Only seven microRNAs were overexpressed in both tumours and serum, suggesting that microRNAs may be released into the serum selectively. Conclusion: The clinical employment of microRNA signatures as a non-invasive diagnostic strategy is promising, but should be further validated for different subtypes of breast cancers. "_A" and "_B" are two tissue sections of the same sample; "_1" and "_2" represents 2 runs of the same sample; na = not available All tissue samples were histologically confirmed by a pathologist using hematoxylin and eosin staining of cryosectioned specimens. One tumour sample was rejected due to failure to detect any tumour cells. Except for two samples (with 30% and 40% tumour cells), all tumour tissues employed had a minimum of 60% tumour cells, as estimated microscopically. Overall, the breast cancer tumour samples had an average of 71% tumour cells. The criteria for adjacent normal tissue were absence of tumour cells and presence of epithelial cells. Hence, after histological confirmation, 31 breast cancer tumours and 23 matched normal tissues were employed for microRNA extraction and profiling using microarray.

Dataset Information

Identification and pathway analysis of microRNAs with no previous involvement in breast cancer.

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