miR-93/106b and Their Host Gene, MCM7, Are Differentially Expressed in Leiomyomas and Functionally Target F3 and IL-8

Abstract

miR-93/106b and their host gene minichromosome maintenance complex component 7 (MCM7) reside at chr7q22, a region frequently rearranged in leiomyomas. We explored the expression of miR-93/106b in leiomyoma and paired myometrium (n = 63) from untreated and patients exposed to hormonal therapies (GnRH agonist, Depo-Provera, and oral contraceptives) from African-Americans and Caucasians and their regulatory functions in isolated paired (n = 15) leiomyoma and myometrial smooth muscle cells and the leiomyosarcoma cell line. At tissue level leiomyomas expressed significantly lower levels of miR-93 and elevated MCM7 as compared with myometrium with limited racial influence or hormonal exposure on their expression. Assessing the regulatory function of miR-93/106b through doxycycline-inducible lentiviral transduction in a microarray analysis, tissue factor (F3) and IL8 were identified as their possible targets. At the tissue level, leiomyomas expressed a significantly lower level of F3 and an elevated IL-8 level, which exhibited an inverse relationship with miR-93 but with limited racial or hormonal influences. The gain of function of miR-93/106b in leiomyoma smooth muscle cells, myometrial smooth muscle cells, and the leiomyosarcoma cell line dose dependently repressed F3 and IL8 through direct interactions with their respective 3'-untranslated region and indirectly through F3 repression inhibited IL8, CTGF, and PAI-1 expression, confirmed by using small interfering RNA silencing or factor Vlla (FVIIa) activation of F3, as well as reducing the rate of proliferation, while increasing caspase-3/7 activity. We concluded that differential expression of miR-93/106b and their direct and/or indirect regulatory functions on F3, IL8, CTGF, and PAI-1 expression, with key roles in inflammation and tissue turnover may be of significance in the outcome of leiomyoma growth and associated symptoms.

MicroRNA miR-93-5p regulates expression of IL-8 and VEGF in neuroblastoma SK-N-AS cells

“…Among the microRNAs, miR-93-5p is clearly demonstrated in a variety of cellular systems to be involved in post-transcriptional regulation of IL-8 and VEGF gene expression (15,(29)(30)(31). For instance, we found that the effects of bacterial challenge activating IL-8 gene transcription in epithelial cells are downregulated by miR-93-5p (29).…”

“…As expected, one of the control levels is transcription-related to the interaction between IL-8 and VEGF promoters and different transcription factors, such as NF-κB, AP-1 and C-EBP/NF-IL-6 (7)(8)(9)(10)(11)(12). In addition, the expression of IL-8 and VEGF genes may be under the control of epigenetic mechanisms, such as those regulated by microRNAs in cancer, differentiation and inflammatory processes (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23).…”

Regulation of miR106b cluster through the RB pathway

“…The mir106b cluster is embedded within the MCM7 gene, which is a direct RB/E2F target gene. 16,[26][27][28][29][30] The mir106b cluster targets the expression of several genes that are directly disease-relevant and that provide a mechanism for cross-talk from the canonical RB pathway to PTEN and p21…”

miR-17 overexpression in cystic fibrosis airway epithelial cells decreases interleukin-8 production

“…HU et al [12] have demonstrated that IL-8 is susceptible to modulation by miR-520b in breast cancer cells, while YU et al [13] have shown that the miR-17/20 cluster regulates the IL-8 3′UTR. Other studies have reported that miR-203 and miR-93/106b regulate IL-8 expression [14,15]. BHATTACHARYYA et al [16] reported how increased levels of miR-155 indirectly elevate IL-8 in CF IB3 cells, CF bronchial brushings and CF neutrophils.…”