Rather, a 51-nucleotide deletion mutation including partial exon 2 of mediator complex subunit 12 (MED12), a gene commonly mutated in leiomyoma, breast fibroadenoma and phyllodes tumor, was identified.
Our results revealed that hsa_circ_0060927 was ectopically expressed in 33.33% of ULM tissues; although, this expression was independent of the MED12 mutation profile in the ULM samples.
MED12 mutations in the fibroids were screened by Sanger sequencing. iTRAQ was used to label the peptides in small-, medium-, and large-sized fibroid samples of annotated MED12 mutation from the same patient.
Unsupervised clustering of results from DNA methylation analyses segregates normal myometrium from fibroids and further segregates the fibroids into subtypes characterized by MED12 mutation or activation of either HMGA2 or HMGA1 expression.
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.
Although the role of MED12 exon 2 mutations is documented in the pathogenesis of uterine leiomyomas, its role in extrauterine smooth muscle tumorigenesis is less clear.
Somatic fibroid-causing mutations in mediator complex subunit 12 (MED12), the most frequent genetic alterations in UFs (up to 85% of tumors), are implicated in transforming normal myometrial stem cells (MSCs) into tumor-forming cells, though the underlying mechanism(s) leading to these mutations remains unknown.
These findings confirm that UF-linked mutations in MED12 disrupt composite Mediator-associated kinase activity and identify CDK8/19 as prospective therapeutic targets in UFs.
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.
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).
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.
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.
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.
Most genetically mutated tumors (27/30; 90%) demonstrated only one type of genetic change, highlighting that even single allele change in MED12 can have profound impact in transforming the normal uterine myometrium to leiomyomas.
Mutations in the N-terminus of MED12 protein occur at high frequency in uterine leiomyomas and breast fibroepithelial tumours, and are frequently found in chronic lymphocytic leukaemia (CLL).
Albeit at a lesser rate, loss of MED12-mutated cells from cell cultures of UL occurs even without passaging thus indicating the requirement of soluble factors or matrix components lacking in vitro.
This study confirmed the previously reported differences and discovered novel differentiating features for MED12-mutation-positive and -negative leiomyomas.