Decreased expression of microRNA-29 family in leiomyoma contributes to increased major fibrillar collagen production

Objective: To determine the expression and function of the microRNA-29 family (miRNA-29a, miRNA-29b, miRNA-29c) in human leiomyoma and myometrium.

Design: Basic science experimental design.

Setting: Academic medical center.

Patient(s): Women undergoing surgery for symptomatic uterine fibroids.

Intervention(s): Overexpression and knockdown of miRNA-29a, miRNA-29b, and miRNA-29c in primary leiomyoma and myometrial cells.

Main outcome measure(s): [1] Expression of the miRNA-29 family members in vivo in leiomyoma versus myometrium; [2] Major fibrillar collagen (I, II, III) expression in leiomyoma and myometrial cells with manipulation of miRNA-29 species.

Result(s): Members of the miRNA-29 family (29a, 29b, 29c) are all down-regulated in leiomyoma versus myometrium in vivo. The expression of the miRNA-29 family can be successfully modulated in primary leiomyoma and myometrial cells. Overexpression of the miRNA-29 family in leiomyoma cells results in down-regulation of the major fibrillar collagens. Down-regulation of the miRNA-29 species in myometrium results in an increase in collagen type III deposition.

Conclusion(s): The miRNA-29 family is consistently down-regulated in leiomyoma compared to matched myometrial tissue. This down-regulation contributes to the increased collagen seen in leiomyomas versus myometrium. When miRNA-29 members are overexpressed in leiomyoma cells, protein levels of all of the major fibrillar collagens decrease. The miRNA-29 members are potential therapeutic targets in this highly prevalent condition.