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Mutation analysis of components of the Mediator kinase module in MED12 mutation-negative uterine leiomyomas.

ABSTRACT: BACKGROUND: Kinase module of Mediator complex ('CDK8 submodule') consists of four subunits: CDK8, Cyclin C, MED12, and MED13. Recently, we reported recurrent MED12 mutations in 70% of uterine leiomyomas. The aim of this study was to analyse whether mutations in other components of the module contribute to the development of these lesions. METHODS: Mutation screening of altogether 70 MED12 mutation-negative uterine leiomyomas was carried out by direct sequencing. RESULTS: None of the tumours displayed somatic mutations in the coding regions of CDK8/CDK19, CCNC, or MED13. CONCLUSIONS: Mutations in CDK8/CDK19, CCNC, and MED13 do not frequently contribute to genesis of uterine leiomyomas.

SUBMITTER: Makinen N

PROVIDER: S-EPMC4007231 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature

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Mutation analysis of components of the Mediator kinase module in MED12 mutation-negative uterine leiomyomas.

Mäkinen N N Heinonen H-R HR Sjöberg J J Taipale J J Vahteristo P P Aaltonen L A LA

British journal of cancer 20140318 9

<h4>Background</h4>Kinase module of Mediator complex ('CDK8 submodule') consists of four subunits: CDK8, Cyclin C, MED12, and MED13. Recently, we reported recurrent MED12 mutations in 70% of uterine leiomyomas. The aim of this study was to analyse whether mutations in other components of the module contribute to the development of these lesions.<h4>Methods</h4>Mutation screening of altogether 70 MED12 mutation-negative uterine leiomyomas was carried out by direct sequencing.<h4>Results</h4>None ...[more]

PMID: 24642626

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Multiple clinical characteristics separate MED12-mutation-positive and -negative uterine leiomyomas.

Project description:Up to 86% of uterine leiomyomas harbour somatic mutations in mediator complex subunit 12 (MED12). These mutations have been associated with conventional histology, smaller tumour size, and larger number of tumours within the uterus. Prior studies, with limited sample sizes, have failed to detect associations between other clinical features and MED12 mutations. Here, we prospectively collected 763 uterine leiomyomas and the corresponding normal myometrial tissue from 244 hysterectomy patients, recorded tumour characteristics, collected clinical data from medical records, and screened the tissue samples for MED12 mutations to assess potential associations between clinical variables and mutation status. Out of 763 leiomyomas, 599 (79%) harboured a MED12 mutation. In the analysis of tumour characteristics, positive MED12-mutation status was significantly associated with smaller tumour size, conventional histology, and subserous location, relative to intramural. In the analysis of clinical variables, the number of MED12-mutation-positive tumours showed an inverse association with parity, and the number of mutation-negative tumours showed a positive association with a history of pelvic inflammatory disease. This study confirmed the previously reported differences and discovered novel differentiating features for MED12-mutation-positive and -negative leiomyomas. These findings emphasise the relevance of specific driver mutations in genesis and presentation of uterine leiomyomas.

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Comparison of Gene expression profiles between myometrium, MED12 mutation positive uterine leiomyomas and MED12 wildtype uterine leiomyomas

Project description:Gene expression profiles of 10 uterine leiomyomas and their matched normal myometrium specimens were studied using Affymetrix GeneChip Human Genome U133 Plus 2.0 gene expression arrays. Four tumors displayed a codon 44 mutation, four carried a intron 1 mutation, and the remaining two displayed no MED12 mutation.

2011-08-26 | GSE30673 | GEO

Expanded Somatic Mutation Spectrum of MED12 Gene in Uterine Leiomyomas of Saudi Arabian Women.

Project description:MED12, a subunit of mediator complex genes is known to harbor genetic mutations, (mostly in exon 2), causal to the genesis of uterine leiomyomas among Caucasian, African American, and Asian women. However, the precise relationship between genetic mutations vs. protein or disease phenotype is not well-explained. Therefore, we sought to replicate the MED12 mutation frequency in leiomyomas of Saudi Arabian women, who represents ethnically and culturally distinct population. We performed molecular screening of MED12 gene (in 308 chromosomes belonging to 154 uterine biopsies), analyzed the genotype-disease phenotype correlations and determined the biophysical characteristics of mutated protein through diverse computational approaches. We discovered that >44% (34/77) leiomyomas of Arab women carry a spectrum of MED12 mutations (30 missense, 1 splice site, and 3 indels). In addition to known codon 44, we observed novel somatic mutations in codons 36, 38, and 55. 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. An interesting inverse correlation between tumor size and LH is observed when tumor is positive to MED12 mutation (p < 0.05). Our computational investigations suggest that amino acid substitution mutations in exon-2 region of MED12 might contribute to potential alterations in phenotype as well as the stability of MED12 protein. Our study, being the first one from Arab world, confirms the previous findings that somatic MED12 mutations are critical to development and progression of uterine leiomyomas irrespective of the ethnic background. We recommend that mutation screening, particularly codon 44 of MED12 can assist in molecular diagnostics of uterine leiomyomas in majority of the patients.

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MED12 mutation activates the tryptophan/kynurenine/AHR pathway to promote growth of uterine leiomyomas.

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MED12 mutations and FH inactivation are mutually exclusive in uterine leiomyomas.

Project description:BackgroundUterine leiomyomas from hereditary leiomyomatosis and renal cell cancer (HLRCC) patients are driven by fumarate hydratase (FH) inactivation or occasionally by mediator complex subunit 12 (MED12) mutations. The aim of this study was to analyse whether MED12 mutations and FH inactivation are mutually exclusive and to determine the contribution of MED12 mutations on HLRCC patients' myomagenesis.MethodsMED12 exons 1 and 2 mutation screening and 2SC immunohistochemistry indicative for FH deficiency was performed on a comprehensive series of HLRCC patients' (122 specimens) and sporadic (66 specimens) tumours. Gene expression analysis was performed using Affymetrix GeneChip Human Exon Arrays (Affymetrix, Santa Clara, CA, USA).ResultsNine tumours from HLRCC patients harboured a somatic MED12 mutation and were negative for 2SC immunohistochemistry. All remaining successfully analysed lesions (107/116) were deficient for FH. Of sporadic tumours, 35/64 were MED12 mutation positive and none displayed a FH defect. In global gene expression analysis FH-deficient tumours clustered together, whereas HLRCC patients' MED12 mutation-positive tumours clustered together with sporadic MED12 mutation-positive tumours.ConclusionsSomatic MED12 mutations and biallelic FH inactivation are mutually exclusive in both HLRCC syndrome-associated and sporadic uterine leiomyomas. The great majority of HLRCC patients' uterine leiomyomas are caused by FH inactivation, but incidental tumours driven by somatic MED12 mutations also occur. These MED12 mutation-positive tumours display similar expressional profiles with their sporadic counterparts and are clearly separate from FH-deficient tumours.

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Differential Expression of MED12-Associated Coding RNA Transcripts in Uterine Leiomyomas.

Project description:Recent studies have demonstrated that somatic MED12 mutations in exon 2 occur at a frequency of up to 80% and have a functional role in leiomyoma pathogenesis. The objective of this study was to elucidate the expression profile of coding RNA transcripts in leiomyomas, with and without these mutations, and their paired myometrium. Next-generation RNA sequencing (NGS) was used to systematically profile the differentially expressed RNA transcripts from paired leiomyomas (n = 19). The differential analysis indicated there are 394 genes differentially and aberrantly expressed only in the mutated tumors. These genes were predominantly involved in the regulation of extracellular constituents. Of the differentially expressed genes that overlapped in the two comparison groups, the magnitude of change in gene expression was greater for many genes in tumors bearing MED12 mutations. Although the myometrium did not express MED12 mutations, there were marked differences in the transcriptome landscape of the myometrium from mutated and non-mutated specimens, with genes regulating the response to oxygen-containing compounds being most altered. In conclusion, MED12 mutations have profound effects on the expression of genes pivotal to leiomyoma pathogenesis in the tumor and the myometrium which could alter tumor characteristics and growth potential.

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Med12 gain-of-function mutation causes leiomyomas and genomic instability.

Project description:Uterine leiomyomas are benign tumors that can cause pain, bleeding, and infertility in some women. Mediator complex subunit 12 (MED12) exon 2 variants are associated with uterine leiomyomas; however, the causality of MED12 variants, their genetic mode of action, and their role in genomic instability have not been established. Here, we generated a mouse model that conditionally expresses a Med12 missense variant (c.131G>A) in the uterus and demonstrated that this alteration alone promotes uterine leiomyoma formation and hyperplasia in both WT mice and animals harboring a uterine mesenchymal cell-specific Med12 deletion. Compared with WT animals, expression of Med12 c.131G>A in conditional Med12-KO mice resulted in earlier onset of leiomyoma lesions that were also greater in size. Moreover, leiomyomatous, Med12 c.131G>A variant-expressing uteri developed chromosomal rearrangements. Together, our results show that the common human leiomyoma-associated MED12 variant can cause leiomyomas in mice via a gain of function that drives genomic instability, which is frequently observed in human leiomyomas.

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Mediator Kinase Disruption in MED12-Mutant Uterine Fibroids From Hispanic Women of South Texas.

Project description:Context:Mutations in the gene encoding Mediator complex subunit MED12 are dominant drivers of uterine fibroids (UFs) in women of diverse racial and ethnic origins. Previously, we showed that UF-linked mutations in MED12 disrupt its ability to activate cyclin C-CDK8/19 in Mediator. However, validation of Mediator kinase disruption in the clinically relevant setting of MED12-mutant UFs is currently lacking. Objective:The objective of this study was twofold. First, to extend the ethnic distribution profile of MED12 mutations by establishing their frequency in UFs from Hispanic women of South Texas. Second, to examine the impact of MED12 mutations on Mediator kinase activity in patient-derived UFs. Methods:We screened 219 UFs from 76 women, including 170 tumors from 57 Hispanic patients, for MED12 exon 2 mutations, and further examined CDK8/19 activity in Mediator complexes immunoprecipitated from MED12 mutation-negative and MED12 mutation-positive UFs. Results:MED12 exon 2 mutations in UFs from Hispanic women are somatic in nature, predominantly monoallelic, and occur at high frequency (54.1%). 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. Analysis of Mediator complexes recovered from patient UFs confirmed this, revealing that Mediator kinase activity is selectively impaired in MED12-mutant UFs. Conclusions:MED12 mutations are important drivers of UF formation in Hispanic women of South Texas. MED12 mutations disrupt Mediator kinase activity, implicating altered CDK8/19 function in UF pathogenesis.

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Comparative analysis of AKT and the related biomarkers in uterine leiomyomas with MED12, HMGA2, and FH mutations.

Project description:Uterine leiomyomas (ULM) are histologically and molecularly heterogeneous and clinically they grow at vastly different rates. Several driver gene mutations have been identified in ULM, including MED12 mutations, HMGA2 overexpression, and biallelic FH inactivation. ULM with different driver mutant genes may use different molecular pathways, but currently no clear correlation between gene mutations and growth related pathways has been established. 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. While ER and PR were highly expressed in all types of ULM, FH ULM showed lower ER expression and higher PR expression. HMGA2 tumors had significantly higher levels of AKT signaling and mitogenic activity than other ULM types. HMGA2 activated AKT signaling through upregulation of IGF2BP2. Silencing HMGA2 in ULM cells resulted in downregulation of AKT and upregulation of p16 and p21, which eventually led to cell senescence. HMGA2 overexpression in ULM is not only related to tumor development but also plays a role in controlling cellular proliferation through the AKT pathway.

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MED12 mutation activates the tryptophan/kynurenine/AHR pathway to promote growth of uterine leiomyomas

Project description:Uterine leiomyoma (LM) is the most common tumor in women. Estrogen and progesterone, via their receptors ERα and PR, play essential roles in LM growth. Mediator complex subunit 12 (MED12) mutations occur in 70% of all LM and are thought to drive tumor growth in a steroid hormone-dependent manner; however, the mechanisms remain unclear. Here, we performed ChIP-seq (ERα, PR, and MED12) and RNA-seq on LM expressing mutant MED12 (mut-MED12) or wild-type MED12 and matched myometrium. Mut-MED12 altered PR and chromatin interaction landscapes, with significant PR-binding site loss in proximal promoter regions in mut-MED12 LM. Integration of cistrome and transcriptome data identified tryptophan 2,3-dioxygenase (TDO2) as a PR and MED12 target gene, which was aberrantly upregulated in mut-MED12 LM. Kynurenine, the catabolic product of TDO2, was significantly elevated in mut-MED12 LM. Tryptophan or kynurenine treatment of primary LM cells activated the aryl hydrocarbon receptor (AHR) pathway, increased cell proliferation, and inhibited apoptosis; blocking the TDO2-kynurenine-AHR pathway by siRNA knockdown or pharmacologic inhibition abolished these effects. Mut-MED12 LM cells showed higher sensitivity to these treatments. These findings suggest that activation of the TDO2-kynurenine-AHR pathway in mut-MED12 LM induces tumor growth, and may inform the development of targeted treatments and precision medicine in LM.

2023-05-01 | GSE204968 | GEO

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