Mechanisms underlying aberrant expression of miR 29c in uterine leiomyoma

Capsule:
Expression of miR-29c is suppressed and inversely correlated with collagen and DNMT3A in leiomyoma. The suppression of miR-29c in leiomyoma smooth muscle cells is primarily mediated by specific protein 1, NF-kB signaling, and epigenetic modification.

Authors:
Tsai-Der Chuang, Ph.D., Omid Khorram, M.D., Ph.D.

Volume 105, Issue 1, Pages 236-245

Abstract:

Objective:
To determine the expression of miR-29c and its target genes in leiomyoma and the role of NF-κB, specific protein 1 (SP1), and DNA methylation in its regulation.

Design:
Experimental study.

Setting:
Academic research laboratory.

Patient(s):
Women undergoing hysterectomy for leiomyoma.

Intervention(s):
Over- and underexpression of miR-29c; blockade of transcription factors.

Main Outcome Measure(s):
MiR-29c and its target gene levels in leiomyoma and the effects of blockade of transcription factors on miR-29c expression.

Result(s):
Leiomyoma as compared with myometrium expressed significantly lower levels of miR-29c, with an inverse relationship with expression of its targets, COL3A1 and DNMT3A. Gain of function of miR-29c inhibited the expression of COL3A1 and DNMT3A at protein and mRNA levels, secreted COL3A1, and rate of cell proliferation. Loss of function of miR-29c had the opposite effect. E2, P, and their combination inhibited miR-29c in leiomyoma smooth muscle cells (LSMC). Phosphorylated NF-κB (p65) and SP1 protein expression were significantly increased in leiomyoma. SiRNA knockdown of SP1 and DNMT3A or their specific inhibitors significantly increased the expression of miR-29c, accompanied by the inhibition of cellular and secreted COL3A1 in siRNA-treated cells. Knockdown of p65 also induced miR-29c expression but had no effect on COL3A1 expression.

Conclusion(s):
MiR-29c expression is suppressed in leiomyoma, resulting in an increase in expression of its targets COL3A1 and DNMT3A. The suppression of miR-29c in LSMC is primarily mediated by SP1, NF-κB signaling, and epigenetic modification. Collectively, these results indicate a significant role for miR-29c in leiomyoma pathogenesis.

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