Differential miRNA expression profiles of primary and relapse lesions of breast cancer patients receiving tamoxifen. Homo sapiens

Long-term tamoxifen treatment significantly improves the survival of hormone receptor-positive (HR+) breast cancer (BC) patients. However, tamoxifen resistance remains a big challenge for endocrine therapy. We aimed to identify prognostic biomarkers for tamoxifen treatment and explore their role in tamoxifen resistance. We used Exiqon miRCURY™ LNA Array (v.18.0) to detect the miRNA expression profiles in the primary tumors and their matched recurrent/metastatic lesions from six HR+ breast cancer patients who relapsed after TAM treatment. Fold changes ≥ 2 and P values < 0.05 were defined as differential expression. We found that 28 miRNAs were significantly downregulated in recurrent/metastatic lesions compared to primary tumors, and 54 miRNAs were significantly upregulated. Overall design: In this study, 6 primary tumor samples and 6 matched recurrent/metastatic lesion samples from six HR+ breast cancer patients who relapsed after TAM treatment were analyzed by microRNA array.