Effect of SMYD3 on the microRNA expression profile of MCF-7 breast cancer cells.

SET and MYND domain containing 3 (SMYD3) is a histone methyltransferase (HMT) and transcription factor, which serves important roles in carcinogenesis. Numerous downstream target genes of SMYD3 have been identified in previous studies. However, the downstream microRNA (miRNA) s regulated by SMYD3 are yet to be elucidated. In the present study, the results of miRNA microarray demonstrated that 30 miRNA expression profiles were upregulated, whilst 24 miRNAs were downregulated by >2.0-fold in the SMYD3-overexpressed MCF-7 breast cancer cells. The HMT activity was demonstrated to be essential for SMYD3-mediated transactivation of miR-200c-3p and the overexpression of miR-200c-3p inhibited the transactivation effects of SMYD3 on myocardin-related transcription factor-A-dependent migration-associated genes. To our best knowledge, the current study is the first to report on the transcriptional regulation of SMYD3 on miRNAs, and miR-200c may be a downstream negative regulator of the SMYD3-mediated pathway in the migration of breast cancer cells. These results may provide a novel theoretical basis to understand the mechanisms underlying the initiation, progression, diagnosis, prevention and therapy of breast cancer.