MicroRNA-127 is downregulated by Tudor-SN protein and contributes to metastasis and proliferation in breast cancer cell line MDA-MB-231.

Tudor-SN is a multifunctional protein that is highly expressed in multiple cancers including breast cancer. Tudor-SN, as a component in RNA-induced splicing complex, was recently reported to regulate gene expression in a microRNA (miRNA)-dependent manner, such as let-7, miR-34a and miR-221. However, how Tudor-SN is associated with cancer development still remains largely elusive. In the present study, we explored the role of Tudor-SN in breast cancer. Stable knockdown of endogenous Tudor-SN, performed on the breast cancer cell line MDA-MB-231 by small hairpin RNA expression vectors, suppressed the in vitro migration and invasion ability of the metastatic breast cancer cell line. Interestingly, we found Tudor-SN as a miRNA regulator according to microarray analysis, and further identified that Tudor-SN negatively regulated the expression of miR-127, and consequently increased the expression of the proto-oncogene BCL6 which was a convincing target of miR-127. Moreover, overexpression of miR-127 reduced the in vitro migration and proliferation ability of breast cancer cell MDA-MB-231. Collectively, our results suggested a novel mechanism that Tudor-SN promoted metastasis and proliferation of breast cancer cells via downregulating the miR-127 expression.