Identification and Pathway Analysis of microRNAs with No Previous Involvement in Breast Cancer

microRNA expression signatures can differentiate normal and breast cancer tissues and can define specific clinico-pathological phenotypes in breast tumors. In order to further evaluate the microRNA expression profile in breast cancer, we analyzed the expression of 667 microRNAs in 29 tumors and 21 adjacent normal tissues using TaqMan Low-density arrays. 130 miRNAs showed significant differential expression (adjusted P value = 0.05, Fold Change = 2) in breast tumors compared to the normal adjacent tissue. Importantly, the role of 43 of these microRNAs has not been previously reported in breast cancer, including several evolutionary conserved microRNA*, showing similar expression rates to that of their corresponding leading strand. The expression of 14 microRNAs was replicated in an independent set of 55 tumors. Bioinformatic analysis of mRNA targets of the altered miRNAs, identified oncogenes like ERBB2, YY1, several MAP kinases, and known tumor-suppressors like FOXA1 and SMAD4. Pathway analysis identified that some biological process which are important in breast carcinogenesis are affected by the altered microRNA expression, including signaling through MAP kinases and TP53 pathways, as well as biological processes like cell death and communication, focal adhesion and ERBB2-ERBB3 signaling. Our data identified the altered expression of several microRNAs whose aberrant expression might have an important impact on cancer-related cellular pathways and whose role in breast cancer has not been previously described

MicroRNAs with the highest differential expression between normal and tumor breast tissue.

<p>MicroRNAs with the highest differential expression between normal and tumor breast tissue.</p

Differentially expressed microRNAs with no previous involvement in breast cancer and cellular pathways affected by their transcriptional targets.

*<p>mRNA targets predicted only with Miranda,</p>**<p>mRNA targets predicted with Miranda and Targetscan,</p>***<p>mRNA targets predicted with Miranda and Pictar.</p

Change in therapeutic management after the EndoPredict assay in a prospective decision impact study of Mexican premenopausal breast cancer patients.

OBJECTIVE:To evaluate the change in adjuvant therapeutic decision in a cohort of young women with breast cancer discussed by a multidisciplinary team, before and after EndoPredict testing. PATIENTS AND METHODS:99 premenopausal women with hormone receptor-positive, HER2-negative, T1-T2, and N0-N1 breast cancer were included. Clinicopathological characteristics were recorded and cases were presented in a multidisciplinary tumor board. Consensual therapeutic decisions before and after EndoPredict results were registered. Medical records were reviewed at six-month follow-up to determine physicians' adherence to therapeutic recommendations. Pearson chi-square and McNemar's tests were used to analyze differences between groups and changes in treatment recommendations, respectively. RESULTS:Median age at diagnosis was 43 years. The most frequent tumor size was pT2 (53.5%) and 27% of patients had 1-3 positive lymph nodes. 46% of patients had a low-risk EPclin result. Nodal status and tumor grade were significantly associated with EPclin result (p < .00001 and p = .0110, respectively), while Ki67 levels and age ≤40 years were not. A change in chemotherapy decision was registered in 19.2% of patients (p = .066), with the greatest impact in de-escalation (9% net reduction). A change in chemotherapy or endocrine therapy regimen was suggested in 19% and 20% of cases, respectively, after EPclin results were available. A significant difference was found in the median EPclin score between patients with a low- vs. high-intensity chemotherapy and endocrine therapy regimen recommendation (p = 0.049 and p = 0.0001, respectively). Tumor board treatment recommendation adherence with the EndoPredict result was 95% and final treatment adherence to EPclin result was 93%. CONCLUSIONS:The EndoPredict test successfully assisted the clinical decision-making process in premenopausal patients, with a clinically significant change in overall decision-making, with the greatest impact seen in chemotherapy reduction, and a high rate of therapeutic adherence

Differentially expressed miRNAs associated with hormone receptor status.

<p>Differentially expressed miRNAs associated with hormone receptor status.</p

Comparison of the expression rate between miRNA-miRNA*.

<p>The bars show the normalized expression values of the microRNA pairs: driver (microRNA) and passenger (miRNA*) strands present in the breast cancer profile.</p

Correlation between FFPE and fresh samples.

<p>A) Unsupervised hierarchical cluster of the delta Ct values of all the analyzed microRNAs represented as a Heat Map. B) Scatter plot of the Ct values in pair-wise comparisons from fresh (T) and FFPE samples (TP).</p

Clinical and pathological information of the sample collection.

<p>IDC: Infiltrating ductal carcinoma, ISDC: In situ ductal carcinoma, ILC: Infiltrating lobular carcinoma, IMC: Infiltrating mucinous carcinoma, NA: Not available.</p

Previously reported miRNAs with differential expression in breast cancer, some of their mRNA targets and the cellular pathways where they participate.

<p>Previously reported miRNAs with differential expression in breast cancer, some of their mRNA targets and the cellular pathways where they participate.</p