The Mediator Complex Subunit 12 (MED-12) Gene and Uterine Fibroids: a Systematic Review

Uterine leiomyomas are the most common tumor of reproductive-age women worldwide. Although benign, uterine fibroids cause significant morbidity and adversely impact the quality of life for affected women. Somatic mutations in the exon 2 of the mediator complex subunit 12 (MED-12) gene represent the most common single gene mutation associated with uterine leiomyomas. The objective of this review was to evaluate the current role of MED-12 mutation in the pathophysiology of uterine fibroids, to assess the prevalence of MED-12 mutation among different populations, and to identify the most common subtypes of MED-12 mutations found in uterine fibroids. A comprehensive search was conducted using Pubmed, Embase, Scopus, and the Web of Science. English-language publications that evaluated MED-12 mutation and uterine fibroids in humans, whether experimental or clinical, were considered. We identified 380 studies, of which 23 were included, comprising 1353 patients and 1872 fibroid tumors. Of the total number of tumors analyzed, 1045 (55.8%) harbored a MED-12 mutation. Among the 23 studies included, the frequency of MED-12 mutation varied from 31.1 to 80% in fibroid samples. The most common type of MED-12 mutation was a heterozygous missense mutation affecting codon 44 of exon 2, specifically the nucleotide 131. Studies reported that MED-12 mutation acts by increasing levels of AKT and disrupting the cyclin C-CDK8/19 kinase activity. The overall average prevalence of MED-12 mutation in uterine fibroids was found to be 55.8% across the global population, though the frequency varied greatly among different countries.

A Systematic Review of Vitamin D and Fibroids: Pathophysiology, Prevention, and Treatment

Uterine fibroids are the most common tumor of reproductive-age women worldwide and cause significant morbidity in affected women. Vitamin D has emerged as a potential therapy for uterine fibroids based on experimental and epidemiologic evidence. The objective of this systematic review was to evaluate the role of vitamin D in the pathophysiology of uterine fibroids and its efficacy for prevention and treatment of fibroids. A comprehensive search was conducted of Cochrane Library, Embase, PubMed, Scopus, and Web of Science from inception to March 2022. English-language publications that evaluated vitamin D and uterine fibroids in humans, whether experimental or clinical, were considered. The search yielded 960 publications, and 89 publications met inclusion criteria: 23 preclinical studies, 25 clinical studies, and 41 review articles. Preclinical studies indicated that the vitamin D receptor was decreased in fibroid cells. Vitamin D treatment of fibroid cells decreased proliferation, extracellular matrix protein expression, and Wnt/β-catenin signaling. Fourteen clinical studies (n = 3535 participants) assessed serum vitamin D level in women with ultrasound-proven fibroids, and all found an inverse correlation between serum vitamin D level and presence of fibroids. Five clinical studies (n = 472 patients) evaluated treatment of fibroids with vitamin D. Four of five studies showed vitamin D significantly inhibited fibroid growth. One pilot study (n = 109 patients) of vitamin D for secondary prevention of fibroids demonstrated smaller recurrent fibroids in the treated group. These studies provide evidence for vitamin D as a therapy for uterine fibroids and underscore the need for well-designed, randomized, placebo-controlled clinical trials.