Serum miR-129 functions as a biomarker for colorectal cancer by targeting estrogen receptor (ER) β.

Aberrantly expressed miRNAs widely participate in the signaling cascades of colorectal carcinogenesis. The present study aimed to identify a potential miRNA that serves as effective biomarker for colorectal cancer (CRC). The expression of estrogen receptorβ (ERβ) was explored using immunohistochemistry. The possible miRNAs targeting ERβ were predicted by TargetScan, and their expression patterns were validated using real time PCR. Dual luciferase reporter assays were performed to determine the potential binding of miR-129 in the 3' untranslated region (3'UTR) of ERβ. In vitro scratch assays and flow cytometry assays were conducted to determine the role of miR-129 on colon cancer cell migration and apoptosis. Proteins related to cell proliferation were determined using western blots. Compared with adjacent non-cancer tissues, the protein level of ERβ was significantly decreased in CRC tissues, and compared with NC the level of miR-129 was significantly increased in blood and tissue samples. Dual luciferase reporter assays demonstrated that ERβ was a direct target gene of miR-129. Further study showed that inhibition of miR-129 decreases HCT116 cell migration and enhances cell apoptosis. More importantly, we found that the silencing of ERβ significantly decreased the activation of caspase3 but increased the protein expression of PCNA. Interestingly, miR-129 inhibitor-induced protein expression pattern changes could be reversed by the siRNA targeting ERβ. The high expression level of circulating miR-129 in the tissue and blood samples of CRC patients contributes to aberrant colon cancer cell proliferation and migration mainly by targeting ERβ.