The regulatory function of miR-200c on inflammatory and cell-cycle associated genes in SK-LMS-1, a leiomyosarcoma cell line.

Uterine leiomyosarcoma is a relatively rare malignancy with high mortality due to metastasis and chemoresistance. Leiomyosarcomas share similar morphological characteristics with leiomyomas which are considered to have the potential of transformation into leiomyosarcoma. Accumulated evidence suggests that microRNAs acting as regulators of gene expression at the posttranscriptional level play key roles in diverse biological processes including cellular transformation and tumorigenesis. We hypothesized that miR-200c, whose expression is altered in leiomyomas, equally plays a key role in pathogenesis of leiomyosarcoma. Using SK-LMS-1 leiomyosarcoma cell line as an in vitro model here, we found that the level of expression of miR-200c was significantly lower as compared to isolated leiomyoma smooth muscle cells. Overexpression (gain-of-function) of miR-200c in SK-LMS-1 through direct interaction with 3'-untranslated region of IKBKB, IL8, CDK2, and CCNE2, respectively, resulted in suppression of their expression as determined by quantitative polymerase chain reaction and Western blot analysis. Additionally, gain-of-function of miR-200c through inhibition of IKBKB expression resulted in decreased p65 transcriptional activity in IL8 promoter. Gain-of-function of miR-200c also increased SK-LMS-1 caspase 3/7 activity and inhibited their proliferation and migration. In summary, the results suggest that a progressive decline in miR-200c expression which alters transcriptional regulation of specific target genes that control nuclear factor-κB signaling pathway, inflammation, cell cycle, and migration, in part may promote development and progression of leiomyosarcomas, including their transformation from leiomyomas.