Mir-671-5p And Mir-638 Serve As Novel Biomarkers For Early Breast Cancer Detection

Breast cancer progression involves stepwise transition from atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC). Percutaneous core needle biopsy (CNB) is the standard procedure after an abnormal mammography finding. However, a CNB diagnosis with either ADH or DCIS is often non-conclusive. A definitive diagnosis relies on surgical excision for further pathological analysis to differentiate simple ADH (sADH) from ADH coexisted with advanced lesions such as DCIS and/or IDC (cADH). Therefore, development of reliable molecular biomarkers is essential to avoid unnecessary surgical excision. microRNAs (miRNAs) are single-stranded non-coding RNAs that play an important role in breast cancer progression. A series of miRNAs that are differentially expressed during stepwise transition of breast carcinogenesis were identified earlier, of which miR-638 and miR-671-5p were functionally characterized. The expression of these miRNAs was decreased gradually from ADH, DCIS, to IDC. We hypothesize that these miRNAs may serve as valuable biomarkers following abnormal mammogram and CNB procedure. Using an improved microdissection protocol, we isolated normal, hyperplasia, DCIS, and/or IDC lesions from FFPE tissue of CNB. We also collected patients’ blood samples before CNB procedure. In addition, we employed the Human 21T breast epithelial cell lines, which were originally derived from the same patient diagnosed with metastatic breast cancer, including H16N2 (normal mammary epithelial), 21PT (ADH), 21NT (DCIS) and 21MT-1 (IDC) for in vitro model study. Real-time qRT-PCR assay was performed for examination of miRNA expression. Cell proliferation and invasion capability were examined by MTT and Transwell assays, respectively after transfection of candidate miRNAs. EMT markers were evaluated by Western blot and Immunofluorescence assays. In clinical samples, we found a synergistic expression pattern between miR-671-5p and miR-638 in cADH but not in sADH lesions. Interestingly, decreased miR-671-5p expression was detected in cADHs, but not in sADHs in both FFPE and serum samples. To explore the potential function of the two miRNAs in the transition from sADH to cADH, we performed further analysis in the Human 21T breast epithelial cell lines. Forced expression of miR-671-5p significantly inhibited cell proliferation in H16N2, 21PT, 21NT and 21MT-1 series cell lines. Overexpression of miR-671-5p attenuated invasion in 21PT, 21NT, and 21MT-1 cell lines but not in H16N2 cell line. Further, miR-671-5p overexpression resulted in significant suppression of mesenchymal marker, vimentin, and promoted the expression of epithelial marker, E-cadherin, in 21PT, 21NT, and 21MT-1cell lines. Our data suggest that miR-671-5p and miR-638 expression in serum and/or CNB tissue may server as a novel companion screening tool following an abnormal mammogram and a subsequent ADH diagnosis by CNB. Citation Format: Xiaohui Tan, Woojin Lee, Xiaoling Wu, Weaam Alshenawy, Danielle Soberman, Katayoon Rezaei, Sana Tabbara, Christine Teal, Robert S. Siegel, Rachel F. Brem, Sidney W. Fu. miR-671-5p and miR-638 serve as novel biomarkers for early breast cancer detection. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1072.