Our study defined the proteome of uterine fibroids and identified that increased ECM protein expression, in particular periostin, is a hallmark of uterine fibroids regardless of MED12 mutation status.
Here, we observed that overexpression of HMGA2 mRNA in tumors measured by quantitative PCR and compared to myometrium is a common phenomenon in fibroids and is frequently associated with MED12 mutations.
MED12 mutations were equally distributed among karyotypically normal and abnormal uterine leiomyomas and were identified in leiomyomas from both black and white American women.
An unsupervised hierarchical clustering analysis revealed two main clusters with one of them (26 of 42 UL) showing an enrichment of MED12 mutated cases (18 of 26 UL).
Whereas 70.0% (14/20) HMGA2-mutated fibroids made their appearance as solitary nodules, 85.5% (153/179) MED12-mutated fibroids occurred as multiple nodules as a rule of independent clonal origin, as reflected by different MED12 mutations.
MED12 mutations were closely associated with the development of uterine leiomyomas, as opposed to other uterine pathologies in Chinese patients, and PCR-based HRMA was found to be a reliable method for the detection of MED12 mutations.
To better define this relationship, we collected ULM with MED12 (n = 25), HMGA2 (n = 15), and FH (n = 27) mutations and examined the sex steroid hormone, cell cycle, and AKT pathway genes by immunohistochemistry.
We identified a minimal cyclin C-CDK8 activation domain on MED12 spanning amino acids 15 through 80 that includes all recorded UF-linked mutations in MED12, suggesting that disruption of Mediator kinase activity is a principal biochemical defect arising from these pathogenic alterations.
Using MED12 sequencing and SNP arrays, we searched for clonally related uterine leiomyomas in a set of 103 tumors from 14 consecutive patients who entered hysterectomy owing to symptomatic lesions.
In order to elucidate molecular and genetic mechanisms responsible for the increased prevalence and morbidity associated with UL in black women, clinical, pathologic, cytogenetic, and select molecular profiling (MED12 mutation analysis) of 75 self-reported black women undergoing surgical treatment for UL was performed.
Recently, we discovered through exome sequencing that as many as 70% of uterine leiomyomas harbour specific mutations in exon 2 of mediator complex subunit 12 (MED12).
Among uterine smooth muscle tumours, MED12 mutations are frequently present in conventional leiomyomas, but are significantly less common in histological variants of leiomyoma and leiomyosarcoma.
The results confirm the occurrence of fibroid-type MED12 mutations in malignant uterine smooth muscle tumors thus suggesting a rare but existing leiomyoma-LMS sequence.
Normal myometrial stem cells may be transformed into tumor-initiating stem cells, causing UFs, due to unknown causes of somatic mutations in MED12, found in up to 85% of sporadically formed UFs.
Cells of one genetic subtype of UL, i.e., those with rearrangements of the high mobility AT-hook 2 protein gene (HMGA2), seem to be able to proliferate in vitro for many passages whereas tumor cells from the much more frequent MED12-mutated lesions barely survive even the first passages.
MED12 is involved in a variety of cellular activities, and mutations in MED12 gene impair MED12 activities and are associated with several diseases, including Opitz-Kaveggia syndrome, Lujan syndrome, uterine leiomyomas and prostate cancer.
The DEGs in the MED12 mutation and wild-type leiomyoma samples, and common DEGs were defined as group A, B and C. Gene Ontology (GO) and pathway enrichment analyses were performed using the Database for Annotation, Visualization and Integrated Discovery online tool.