Gene Summary

Gene:MED12; mediator complex subunit 12
Aliases: OKS, FGS1, HOPA, OPA1, OHDOX, ARC240, CAGH45, MED12S, TNRC11, TRAP230
Summary:The initiation of transcription is controlled in part by a large protein assembly known as the preinitiation complex. A component of this preinitiation complex is a 1.2 MDa protein aggregate called Mediator. This Mediator component binds with a CDK8 subcomplex which contains the protein encoded by this gene, mediator complex subunit 12 (MED12), along with MED13, CDK8 kinase, and cyclin C. The CDK8 subcomplex modulates Mediator-polymerase II interactions and thereby regulates transcription initiation and reinitation rates. The MED12 protein is essential for activating CDK8 kinase. Defects in this gene cause X-linked Opitz-Kaveggia syndrome, also known as FG syndrome, and Lujan-Fryns syndrome. [provided by RefSeq, Aug 2009]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:mediator of RNA polymerase II transcription subunit 12
Source:NCBIAccessed: 29 August, 2019


What does this gene/protein do?
Show (20)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 29 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Proportional Hazards Models
  • Genotype
  • Leiomyosarcoma
  • X Chromosome
  • Vena Cava, Inferior
  • Phyllodes Tumor
  • HMGA2
  • Neoplasms, Experimental
  • Mediator Complex
  • Breast Cancer
  • Wnt4 Protein
  • DNA Mutational Analysis
  • Cell Proliferation
  • Exons
  • Adolescents
  • Myometrium
  • Smooth Muscle Tumor
  • Genetic Predisposition
  • Mutation
  • Missense Mutation
  • Prostate Cancer
  • Chromosome Aberrations
  • Exome
  • Gene Expression Profiling
  • High-Throughput Nucleotide Sequencing
  • Transforming Growth Factor beta
  • Leiomyoma
  • Immunohistochemistry
  • beta Catenin
  • Soft Tissue Sarcoma
  • Fibroadenoma
  • Neoplasm Recurrence, Local
  • Phenotype
  • Uterine Cancer
  • Adrenocortical Cancer
  • Genomics
  • Base Sequence
  • Republic of Korea
  • Cancer Gene Expression Regulation
  • Young Adult
  • World Health Organization
  • Biomarkers, Tumor
Tag cloud generated 29 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Uterine SarcomaMED12 and Uterine Cancer View Publications78
Breast CancerMED12 and Breast Cancer View Publications35
Prostate CancerMED12 and Prostate Cancer View Publications10
Soft Tissue SarcomaMED12 and Soft Tissue Cancers View Publications4
Adrenocortical CancerMED12 and Adrenocortical Carcinoma
Assié, et al (2014) identified recurrent alterations in MED12 in a GWAS study of 45 Adrenocortical carcinomas, with results verified in a further independent set of 77 samples.
View Publications1

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: MED12 (cancer-related)

Bullerdiek J, Rommel B
Factors targeting
F1000Res. 2018; 7:359 [PubMed] Free Access to Full Article Related Publications
Mediator Complex Subunit 12 (MED12) is part of the transcriptional preinitiation machinery. Mutations of its gene predominantly occur in two types of highly frequent benign tumors, uterine leiomyomas and fibroadenomas of the breast, where they apparently act as driver mutations. Nevertheless, their presence is not restricted to benign tumors having been found at considerable frequencies in uterine leiomyosarcomas, malignant phyllodes tumors, and chronic lymphocytic leukemia also. Most of the mutations are located within exon 2 of the gene but in rare cases the intron 1/exon 2 boundary or exon 1 are affected. As to their type, predominantly single nucleotide exchanges with a hotspot in one codon are found, but small deletions clustering around that hotspot also are not uncommon. These latter deletions are leaving the open reading frame intact. As to the types of mutations, so far no apparent differences between the tumor entities affected have emerged. Interestingly, this pattern with small deletions clustered around the hotspot of single nucleotide exchanges resembles that seen as a result of targeted gene editing. In contrast to other driver mutations the percentage of

Asano R, Asai-Sato M, Matsukuma S, et al.
Expression of erythropoietin messenger ribonucleic acid in wild-type MED12 uterine leiomyomas under estrogenic influence: new insights into related growth disparities.
Fertil Steril. 2019; 111(1):178-185 [PubMed] Related Publications
OBJECTIVE: To determine factors that impact erythropoietin (EPO) production in leiomyomas. We have previously implicated EPO production in promoting the growth of some leiomyomas.
DESIGN: The relationship between EPO messenger RNA (mRNA) expression and MED12 gene mutations or mRNA expression levels of high-mobility group AT-hook (HMGA) 1 and HMGA2 were analyzed. Effects of 10
SETTING: Graduate school of medicine.
PATIENT(S): Patients with leiomyoma.
INTERVENTION(S): We used tissue samples and clinical data of 108 patients with leiomyomas to analyze the relation between EPO mRNA expression and MED12 mutation. Tissue samples from another 10 patients with leiomyomas were collected for in vitro experimentation using primary cultures of leiomyoma and myometrial cells.
MAIN OUTCOME MEASURE(S): Relations between EPO mRNA expression, MED12 exon 2 mutation, and HMGA1/HMGA2 mRNA expression levels in leiomyoma samplings, in addition to effects of estrogen (E) on EPO mRNA expression in cultures of leiomyoma cells.
RESULT(S): The EPO mRNA level was threefold higher in leiomyomas with wild-type (vs. mutated) MED12 genes. There was no correlation between EPO and HMGA1 or HMGA2 mRNA expression levels. In wild-type MED12 leiomyomas only, E
CONCLUSION(S): The EPO mRNA expression increased significantly after E

Liu S, Yin P, Kujawa SA, et al.
Progesterone receptor integrates the effects of mutated MED12 and altered DNA methylation to stimulate RANKL expression and stem cell proliferation in uterine leiomyoma.
Oncogene. 2019; 38(15):2722-2735 [PubMed] Free Access to Full Article Related Publications
Progesterone and its receptor, PR, are essential for uterine leiomyoma (LM, a.k.a., fibroid) tumorigenesis, but the underlying cellular and molecular mechanisms remain unclear. The receptor activator of NF-κB (RANKL) was recently identified as a novel progesterone/PR-responsive gene that plays an important role in promoting LM growth. Here, we used RANKL as a representative gene to investigate how steroid hormone, genetic, and epigenetic signals are integrated to regulate LM stem cell (LSC) function. We demonstrated that RANKL specifically upregulates LSC proliferation through activation of Cyclin D1. RANKL gene transcription was robustly induced by the progesterone agonist R5020, leading to a dramatically higher RANKL expression in LM compared to adjacent myometrial (MM) tissue. MethylCap-Seq revealed a differentially methylated region (DMR) adjacent to the distal PR-binding site (PRBS) 87 kb upstream of the RANKL transcription start site. Hypermethylation of the DMR inhibited recruitment of PR to the adjacent PRBS. Luciferase assays indicated that the DMR and distal PRBS constitute a novel RANKL distal regulatory element that actively regulates RANKL expression. Furthermore, MED12 physically interacts with PR in LM tissue. The interaction between MED12 and PR, binding of PR and MED12 to PRBS, and RANKL gene expression are significantly higher in LM containing a distinct MED12 mutation (G44D) than in LM with wild-type MED12. In summary, our findings suggest that DNA methylation and MED12 mutation together constitute a complex regulatory network that affects progesterone/PR-mediated RANKL gene expression, with an important role in activating stem cell proliferation and fibroid tumor development.

Lim SZ, Ng CCY, Rajasegaran V, et al.
Genomic profile of breast sarcomas: a comparison with malignant phyllodes tumours.
Breast Cancer Res Treat. 2019; 174(2):365-373 [PubMed] Related Publications
PURPOSE: We aimed to investigate the genomic profile of breast sarcomas (BS) and compare with that of malignant phyllodes tumours (MPT).
METHODS: DNA was extracted from formalin-fixed, paraffin-embedded (FFPE) specimens from 17 cases of BS diagnosed at Singapore General Hospital from January 1991 to December 2014. Targeted deep sequencing and copy number variation (CNV) analysis on 16 genes, which included recurrently mutated genes in phyllodes tumours and genes associated with breast cancer, were performed on these samples. Genetic alterations (GA) observed were summarised and analysed.
RESULTS: Nine cases met the quality control requirements for both targeted deep sequencing and CNV analysis. Three (33.33%) were angiosarcomas and 6 (66.67%) were non-angiosarcomas. In the non-angiosarcoma group, 83.33% (n = 5) of the patients had GA in the TERT gene. The other commonly mutated genes in this group of tumours were MED12 (n = 4, 66.67%), BCOR (n = 4, 66.67%), KMT2D (n = 3, 50%), FLNA (n = 3, 50%) and NF1 (n = 3, 50%). In contrast, none of the angiosarcomas had mutations or copy number alterations in TERT, MED12, BCOR, FLNA or NF1. Eighty percent of patients with GA in TERT (n = 5) had concurrent mutations in MED12. Sixty percent (n = 3) of these cases also demonstrated GA in NF1, PIK3CA or EGFR which are known cancer driver genes.
CONCLUSIONS: The non-angiosarcoma group of BS was found to share similar GA as those described for MPT, which may suggest a common origin and support their consideration as a similar group of tumours with regard to management and prognostication.

Pareja F, Da Cruz Paula A, Murray MP, et al.
J Clin Pathol. 2019; 72(3):258-262 [PubMed] Free Access to Full Article Related Publications
AIMS: Most benign breast fibroepithelial lesions (FEL) in adults harbour recurrent somatic
METHODS: DNA from 21 consecutive FAs and eight consecutive BePTs in adolescents and young adults was subjected to Sanger sequencing of the exon 2 of
RESULTS: We identified
CONCLUSIONS: As in adults, benign FELs in juvenile patients harbour recurrent

Mello JBH, Barros-Filho MC, Abreu FB, et al.
MicroRNAs involved in the HMGA2 deregulation and its co-occurrence with MED12 mutation in uterine leiomyoma.
Mol Hum Reprod. 2018; 24(11):556-563 [PubMed] Related Publications
STUDY QUESTION: Can the mediator complex subunit 12 (MED12) mutation and high mobility group AT-hook 2 (HMGA2) overexpression co-occurrence be explained by the alternative mechanism of HMGA2 dysregulation in uterine leiomyomas (UL)?
SUMMARY ANSWER: The co-occurrence of MED12 mutation and HMGA2 overexpression, and a negative correlation of five validated or predicted microRNAs that target HMGA2 were reported.
WHAT IS KNOWN ALREADY: The recent stratification of UL, according to recurrent and mutually exclusive genomic alterations affecting HMGA2, MED12, fumarate hydratase (FH) and collagen type IV alpha 5-alpha 6 (COL4A5-COL4A6) pointed out the involvement of distinct molecular pathways. However, the mechanisms of regulation involving these drivers are poorly explored.
STUDY DESIGN, SIZE, DURATION: A total of 78 UL and 34 adjacent normal myometrium (NM) tissues was collected from 56 patients who underwent hysterectomies at a single institution. The patients were treated at the Department of Gynecology and Obstetrics, School of Medicine, Sao Paulo State University, Botucatu, SP, Brazil, from October 1995 to February 2004.
PARTICIPANTS/MATERIALS, SETTING, METHODS: Gene expression profiling was evaluated from fresh frozen tissues and compared with MED12 mutations at exon 2. In addition, RT-qPCR was applied to evaluate the expression levels of HMGA2 and their predictive miRNA regulators: hsa-let-7a, miR-26a, miR-26b, mir-93 and mir-106b.
MAIN RESULTS AND THE ROLE OF CHANCE: 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). Increased expression levels of HMGA2 were observed in both clusters, including cases with MED12 mutation (cluster 1:18 UL). A significant HMGA2 overexpression (P < 0.001) in UL in comparison with NM was found. Five miRNAs predicted to regulate HMGA2 were significantly downregulated (P < 0.001) and negatively correlated to HMGA2 expression levels (P < 0.05) in UL.
LIMITATIONS REASONS FOR CAUTION: An in vivo functional study was not performed to validate the microRNAs and HMGA2 interaction due to technical limitations.
WIDER IMPLICATIONS OF THE FINDINGS: HMGA2 overexpression was detected in a significant number of MED12 mutated ULs, suggesting that these alterations coexist. Furthermore, five miRNAs were described as potential regulators of HMGA2 expression in UL.
LARGE-SCALE DATA: Data available in the Gene Expression Omnibus GSE42939.
STUDY FUNDING AND COMPETING INTEREST(S): This study was supported by grants from Fundação de Amparo a Pesquisa do Estado de São Paulo (# 2008/58835-2) and Conselho Nacional de Pesquisa (# 485032/2007-4), Brazil. The authors declared having no conflicts of interest.

Välimäki N, Kuisma H, Pasanen A, et al.
Genetic predisposition to uterine leiomyoma is determined by loci for genitourinary development and genome stability.
Elife. 2018; 7 [PubMed] Free Access to Full Article Related Publications
Uterine leiomyomas (ULs) are benign tumors that are a major burden to women's health. A genome-wide association study on 15,453 UL cases and 392,628 controls was performed, followed by replication of the genomic risk in six cohorts. Effects of the risk alleles were evaluated in view of molecular and clinical characteristics. 22 loci displayed a genome-wide significant association. The likely predisposition genes could be grouped to two biological processes. Genes involved in genome stability were represented by

Galindo LJ, Hernández-Beeftink T, Salas A, et al.
HMGA2 and MED12 alterations frequently co-occur in uterine leiomyomas.
Gynecol Oncol. 2018; 150(3):562-568 [PubMed] Related Publications
OBJECTIVE: Around 70% of uterine leiomyomas show MED12 mutations while overexpression of HMGA2 mRNA is also highly frequent in fibroids. However, previous studies suggested that alterations in both genes are mutually exclusive. In the present study, we searched for mutation in MED12 and analyzed the expression of HMGA2 in 20 uterine leiomyomas and their matched myometrium.
METHODS: Normal and tumor tissue obtained from premenopausal women who underwent hysterectomy were collected after surgery and DNA, RNA and proteins were isolated and analyzed for MED12 mutations using Sanger sequencing, HMGA2 mRNA expression by quantitative PCR and HMGA2 protein detection by western blot and immunohistochemistry.
RESULTS: 75% of the tumors displayed MED12 mutation while 65% of them showed overexpression of HMGA2 mRNA in leiomyomata compared to myometrial tissues (p = 0,0008). Interestingly, 50% of the tumors showed mutations in MED12 and overexpression of HMGA2 mRNA simultaneously, suggesting that alterations in both genes are relatively frequent in uterine leiomyomas.
CONCLUSIONS: Contrary to the present findings, former studies showed that mutations in MED12 and overexpression of HMGA2 are mutually exclusive. 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. In addition, the common clonal origin of tumors overexpressing HMGA2 mRNA and its expression in few myometrial tissue points to HMGA2 up-regulation as an early event in leiomyoma tumorigenesis.

Tay TKY, Guan P, Loke BN, et al.
Molecular insights into paediatric breast fibroepithelial tumours.
Histopathology. 2018; 73(5):809-818 [PubMed] Related Publications
AIMS: This study aims to examine the molecular genetics of paediatric breast fibroepithelial tumours through the targeted sequencing of 50 genes.
METHODS AND RESULTS: Formalin-fixed paraffin-embedded tissues of fibroepithelial tumours diagnosed in a cohort of patients aged 18 years and below were subjected to next generation sequencing using the Haloplex Target Enrichment System. Twenty-five conventional and 17 juvenile fibroadenomas were studied, with MED12 mutations found in 53.8 and 35% of the tumours, respectively. There was also one benign fibroepithelial neoplasm with hybrid features of juvenile papillomatosis and infarcted benign phyllodes tumour-like areas. Most tumours did not have mutations in well-known cancer driver genes, none harboured TERT promoter mutations, while 25.6% (11 of 43) showed no mutations. Metachronous and synchronous tumours were found to have mutational heterogeneity with some containing mutations in MED12; other genes or no mutations were detected at all. Four of eight giant fibroadenomas (size 5 cm or larger) had no mutations detected, suggesting that there are other molecular mechanisms driving their growth. Tumours with MED12 mutations incidentally had a significantly higher stromal mitotic count compared with those without.
CONCLUSION: While paediatric fibroepithelial lesions can have cellular stroma potentially raising concern for phyllodes tumour, their lack of TERT promoter and cancer driver mutations is reassuring. The absence of mutations in a significant proportion of tumours, especially the giant fibroadenomas, warrants investigation of pathogenetic mechanisms beyond those involving the 50 genes.

Hu ZY, Xie N, Tian C, et al.
Identifying Circulating Tumor DNA Mutation Profiles in Metastatic Breast Cancer Patients with Multiline Resistance.
EBioMedicine. 2018; 32:111-118 [PubMed] Free Access to Full Article Related Publications
PURPOSE: In cancer patients, tumor gene mutations contribute to drug resistance and treatment failure. In patients with metastatic breast cancer (MBC), these mutations increase after multiline treatment, thereby decreasing treatment efficiency. The aim of this study was to evaluate gene mutation patterns in MBC patients to predict drug resistance and disease progression.
METHOD: A total of 68 MBC patients who had received multiline treatment were recruited. Circulating tumor DNA (ctDNA) mutations were evaluated and compared among hormone receptor (HR)/human epidermal growth factor receptor 2 (HER2) subgroups.
RESULTS: The baseline gene mutation pattern (at the time of recruitment) varied among HR/HER2 subtypes. BRCA1 and MED12 were frequently mutated in triple negative breast cancer (TNBC) patients, PIK3CA and FAT1 mutations were frequent in HR+ patients, and PIK3CA and ERBB2 mutations were frequent in HER2+ patients. Gene mutation patterns also varied in patients who progressed within either 3 months or 3-6 months of chemotherapy treatment. For example, in HR+ patients who progressed within 3 months of treatment, the frequency of TERT mutations significantly increased. Other related mutations included FAT1 and NOTCH4. In HR+ patients who progressed within 3-6 months, PIK3CA, TP53, MLL3, ERBB2, NOTCH2, and ERS1 were the candidate mutations. This suggests that different mechanisms underlie disease progression at different times after treatment initiation. In the COX model, the ctDNA TP53 + PIK3CA gene mutation pattern successfully predicted progression within 6 months.
CONCLUSION: ctDNA gene mutation profiles differed among HR/HER2 subtypes of MBC patients. By identifying mutations associated with treatment resistance, we hope to improve therapy selection for MBC patients who received multiline treatment.

Xie J, Ubango J, Ban Y, et al.
Comparative analysis of AKT and the related biomarkers in uterine leiomyomas with MED12, HMGA2, and FH mutations.
Genes Chromosomes Cancer. 2018; 57(10):485-494 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
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.

Katoh M
Multi‑layered prevention and treatment of chronic inflammation, organ fibrosis and cancer associated with canonical WNT/β‑catenin signaling activation (Review).
Int J Mol Med. 2018; 42(2):713-725 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
β‑catenin/CTNNB1 is an intracellular scaffold protein that interacts with adhesion molecules (E‑cadherin/CDH1, N‑cadherin/CDH2, VE‑cadherin/CDH5 and α‑catenins), transmembrane‑type mucins (MUC1/CD227 and MUC16/CA125), signaling regulators (APC, AXIN1, AXIN2 and NHERF1/EBP50) and epigenetic or transcriptional regulators (BCL9, BCL9L, CREBBP/CBP, EP300/p300, FOXM1, MED12, SMARCA4/BRG1 and TCF/LEF). Gain‑of‑function CTTNB1 mutations are detected in bladder cancer, colorectal cancer, gastric cancer, liver cancer, lung cancer, pancreatic cancer, prostate cancer and uterine cancer, whereas loss‑of‑function CTNNB1 mutations are also detected in human cancer. ABCB1, ALDH1A1, ASCL2, ATF3, AXIN2, BAMBI, CCND1, CD44, CLDN1, CTLA4, DKK1, EDN1, EOMES, FGF18, FGF20, FZD7, IL10, JAG1, LEF1, LGR5, MITF, MSX1, MYC, NEUROD1, NKD1, NODAL, NOTCH2, NOTUM, NRCAM, OPN, PAX3, PPARD, PTGS2, RNF43, SNAI1, SP5, TCF7, TERT, TNFRSF19, VEGFA and ZNRF3 are representative β‑catenin target genes. β‑catenin signaling is involved in myofibroblast activation and subsequent pulmonary fibrosis, in addition to other types of fibrosis. β‑catenin and NF‑κB signaling activation are involved in field cancerization in the stomach associated with Helicobacter pylori (H. pylori) infection and in the liver associated with hepatitis C virus (HCV) infection and other etiologies. β‑catenin‑targeted therapeutics are functionally classified into β‑catenin inhibitors targeting upstream regulators (AZ1366, ETC‑159, G007‑LK, GNF6231, ipafricept, NVP‑TNKS656, rosmantuzumab, vantictumab, WNT‑C59, WNT974 and XAV939), β‑catenin inhibitors targeting protein‑protein interactions (CGP049090, CWP232228, E7386, ICG‑001, LF3 and PRI‑724), β‑catenin inhibitors targeting epigenetic regulators (PKF118‑310), β‑catenin inhibitors targeting mediator complexes (CCT251545 and cortistatin A) and β‑catenin inhibitors targeting transmembrane‑type transcriptional outputs, including CD44v6, FZD7 and LGR5. Eradicating H. pylori and HCV is the optimal approach for the first‑line prevention of gastric cancer and hepatocellular carcinoma (HCC), respectively. However, β‑catenin inhibitors may be applicable for the prevention of organ fibrosis, second‑line HCC prevention and treating β‑catenin‑driven cancer. The multi‑layered prevention and treatment strategy of β‑catenin‑related human diseases is necessary for the practice of personalized medicine and implementation of precision medicine.

De Bie J, Demeyer S, Alberti-Servera L, et al.
Single-cell sequencing reveals the origin and the order of mutation acquisition in T-cell acute lymphoblastic leukemia.
Leukemia. 2018; 32(6):1358-1369 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Next-generation sequencing has provided a detailed overview of the various genomic lesions implicated in the pathogenesis of T-cell acute lymphoblastic leukemia (T-ALL). Typically, 10-20 protein-altering lesions are found in T-ALL cells at diagnosis. However, it is currently unclear in which order these mutations are acquired and in which progenitor cells this is initiated. To address these questions, we used targeted single-cell sequencing of total bone marrow cells and CD34

Luo XL, Deng CC, Su XD, et al.
Loss of MED12 Induces Tumor Dormancy in Human Epithelial Ovarian Cancer via Downregulation of EGFR.
Cancer Res. 2018; 78(13):3532-3543 [PubMed] Related Publications
A high rate of disease relapse makes epithelial ovarian cancer (EOC) the leading cause of death among all gynecologic malignancies. These relapses are often due to tumor dormancy. Here we identify the RNA polymerase II transcriptional mediator subunit 12 (MED12) as an important molecular regulator of tumor dormancy. MED12 knockout (KO) induced dormancy of EOC cells

Hayden MA, Ordulu Z, Gallagher CS, et al.
Clinical, pathologic, cytogenetic, and molecular profiling in self-identified black women with uterine leiomyomata.
Cancer Genet. 2018; 222-223:1-8 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Black women are disproportionately affected by uterine leiomyomata (UL), or fibroids, compared to other racial groups, having a greater lifetime risk of developing UL and an earlier age of diagnosis. 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. Our observations are broadly representative of previous cytogenetic studies of UL: karyotypically abnormal tumors were detected in 30.7% of women and 17.4% of analyzed tumors. No notable association was observed between race and increased occurrence of cytogenetic abnormalities that might contribute to any population-specific morbidity or prevalence rate. Our data on MED12 mutation analyses (73.2% of tumors harbored a MED12 mutation) provide additional support for a significant role of MED12 in tumorigenesis. Although the effect of MED12-mediated tumorigenesis appears significant irrespective of race, other genetic events such as the distribution of karyotypic abnormalities appear differently in black women. This case series indicates that presently recognized genetic and molecular characteristics of UL do not appear to explain the increased prevalence and morbidity of UL in black women.

Tsuyoshi H, Yoshida Y
Molecular biomarkers for uterine leiomyosarcoma and endometrial stromal sarcoma.
Cancer Sci. 2018; 109(6):1743-1752 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Uterine leiomyosarcoma (u-LMS) and endometrial stromal sarcoma (ESS) are among the most frequent soft tissue sarcomas, which, in adults, lead to fatal lung metastases and patients have an extremely poor prognosis. Due to their rarity and heterogeneity, there are no suitable biomarkers for diagnosis and prognosis, although some biomarker candidates have appeared. In 2017, The Cancer Genome Atlas (TCGA) Research Network's work on u-LMS has confirmed mutations and deletions in RB1, TP53 and PTEN. In addition, whole-exome sequencing of u-LMS has confirmed and demonstrated frequent alterations in TP53, RB1, α-thalassemia/mental retardation syndrome X-linked (ATRX) and mediator complex subunit 12 (MED12). MED12 is a useful biomarker to diagnose uterine-derived LMS and tumors arising from (LM) with a relatively favorable prognosis. TP53 and ATRX mutations can be important mechanisms in the pathogenesis of u-LMS and are correlated with a poor prognosis. In an update based on the 2014 WHO classification, low-grade ESS is often associated with gene rearrangement bringing about the JAZF 1-SUZ12 (formerly JAZF1-JJAZ1) fusion gene, whereas high-grade ESS is associated with the YWHAE-NUTM fusion gene. Low-grade ESS with JAZF1 rearrangement may correlate with metastasis. However, high-grade ESS with metastasis with YWHAE rearrangement shows a relatively favorable prognosis. The genetic/molecular genetic aberrations in u-LMS and ESS are reviewed, focusing on molecular biomarkers for these primary and metastatic tumors.

Gao WW, Xiao RQ, Zhang WJ, et al.
JMJD6 Licenses ERα-Dependent Enhancer and Coding Gene Activation by Modulating the Recruitment of the CARM1/MED12 Co-activator Complex.
Mol Cell. 2018; 70(2):340-357.e8 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Whereas the actions of enhancers in gene transcriptional regulation are well established, roles of JmjC-domain-containing proteins in mediating enhancer activation remain poorly understood. Here, we report that recruitment of the JmjC-domain-containing protein 6 (JMJD6) to estrogen receptor alpha (ERα)-bound active enhancers is required for RNA polymerase II recruitment and enhancer RNA production on enhancers, resulting in transcriptional pause release of cognate estrogen target genes. JMJD6 is found to interact with MED12 in the mediator complex to regulate its recruitment. Unexpectedly, JMJD6 is necessary for MED12 to interact with CARM1, which methylates MED12 at multiple arginine sites and regulates its chromatin binding. Consistent with its role in transcriptional activation, JMJD6 is required for estrogen/ERα-induced breast cancer cell growth and tumorigenesis. Our data have uncovered a critical regulator of estrogen/ERα-induced enhancer coding gene activation and breast cancer cell potency, providing a potential therapeutic target of ER-positive breast cancers.

Liu X, Liu Y, Zhao J, Liu Y
Screening of potential biomarkers in uterine leiomyomas disease via gene expression profiling analysis.
Mol Med Rep. 2018; 17(5):6985-6996 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
The present study aimed to screen potential biomarkers for uterine leiomyomas disease, particularly target genes associated with the mediator of RNA polymerase II transcription subunit 12 (MED12) mutation. The microarray data of GSE30673, including 10 MED12 wild-type myometrium, 8 MED12 mutation leiomyoma and 2 MED12 wild-type leiomyoma samples, were downloaded from the Gene Expression Omnibus database. Compared with myometrium samples, differently-expressed genes (DEGs) in the MED12 mutation and wild-type leiomyoma samples were identified using the Limma package. The two sets of DEGs obtained were intersected to screen common DEGs. 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. Based on the Kyoto Encyclopedia of Genes and Genomes database, pathway relation networks were constructed. DEGs in GO terms and pathways were intersected to screen important DEGs. Subsequently, a gene co‑expression network was constructed and visualized using Cytoscape software. Reverse transcription‑quantitative polymerase chain reaction was used to detect the expression levels of important DEGs. A total of 1,258 DEGs in group A were screened, and enriched for extracellular matrix (ECM) organization and ECM‑receptor interaction. In addition, a total of 1,571 DEGs in group B were enriched for cell adhesion. Furthermore, 391 DEGs were involved in extracellular matrix organization. Pathway relation networks of group A, B and C were constructed with nodes of 48, 39, and 28, respectively. Finally, 135 important DEGs were obtained, including Acyl‑CoA synthetase medium‑chain family member 3, protein S (α) (PROS1) and F11 receptor. A gene co‑expression network with 68 nodes was constructed. The expression of caspase 1 (CASP1) and aldehyde dehydrogenase 1 family member A1 (ALDH1A1) was significant higher in SK‑UT‑1 compared with that in PHM1‑31 cells, while the expression of PROS1 was significant lower in SK‑UT‑1 cells. These results that CASP1, ALDH1A1 and PROS1 may be potential biomarkers for uterine leiomyomas. Furthermore, hematopoietic prostaglandin D synthase and carbonyl reductase 3 (CBR3) may be particular genes associated with the MED12 mutation in this disease.

Kuuluvainen E, Domènech-Moreno E, Niemelä EH, Mäkelä TP
Depletion of Mediator Kinase Module Subunits Represses Superenhancer-Associated Genes in Colon Cancer Cells.
Mol Cell Biol. 2018; 38(11) [PubMed] Article available free on PMC after 01/10/2019 Related Publications
In cancer, oncogene activation is partly mediated by acquired superenhancers, which therefore represent potential targets for inhibition. Superenhancers are enriched for BRD4 and Mediator, and both BRD4 and the Mediator MED12 subunit are disproportionally required for expression of superenhancer-associated genes in stem cells. Here we show that depletion of Mediator kinase module subunit MED12 or MED13 together with MED13L can be used to reduce expression of cancer-acquired superenhancer genes, such as the MYC gene, in colon cancer cells, with a concomitant decrease in proliferation. Whereas depletion of MED12 or MED13/MED13L caused a disproportional decrease of superenhancer gene expression, this was not seen with depletion of the kinases cyclin-dependent kinase 9 (CDK8) and CDK19. MED12-MED13/MED13L-dependent superenhancer genes were coregulated by β-catenin, which has previously been shown to associate with MED12. Importantly, β-catenin depletion caused reduced binding of MED12 at the MYC superenhancer. The effect of MED12 or MED13/MED13L depletion on cancer-acquired superenhancer gene expression was more specific than and partially distinct from that of BRD4 depletion, with the most efficient inhibition seen with combined targeting. These results identify a requirement of MED12 and MED13/MED13L for expression of acquired superenhancer genes in colon cancer, implicating these Mediator subunits as potential therapeutic targets for colon cancer, alone or together with BRD4.

Rhine CL, Cygan KJ, Soemedi R, et al.
Hereditary cancer genes are highly susceptible to splicing mutations.
PLoS Genet. 2018; 14(3):e1007231 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Substitutions that disrupt pre-mRNA splicing are a common cause of genetic disease. On average, 13.4% of all hereditary disease alleles are classified as splicing mutations mapping to the canonical 5' and 3' splice sites. However, splicing mutations present in exons and deeper intronic positions are vastly underreported. A recent re-analysis of coding mutations in exon 10 of the Lynch Syndrome gene, MLH1, revealed an extremely high rate (77%) of mutations that lead to defective splicing. This finding is confirmed by extending the sampling to five other exons in the MLH1 gene. Further analysis suggests a more general phenomenon of defective splicing driving Lynch Syndrome. Of the 36 mutations tested, 11 disrupted splicing. Furthermore, analyzing past reports suggest that MLH1 mutations in canonical splice sites also occupy a much higher fraction (36%) of total mutations than expected. When performing a comprehensive analysis of splicing mutations in human disease genes, we found that three main causal genes of Lynch Syndrome, MLH1, MSH2, and PMS2, belonged to a class of 86 disease genes which are enriched for splicing mutations. Other cancer genes were also enriched in the 86 susceptible genes. The enrichment of splicing mutations in hereditary cancers strongly argues for additional priority in interpreting clinical sequencing data in relation to cancer and splicing.

Jiang J, He M, Hu X, et al.
Deep sequencing reveals the molecular pathology characteristics between primary uterine leiomyoma and pulmonary benign metastasizing leiomyoma.
Clin Transl Oncol. 2018; 20(8):1080-1086 [PubMed] Related Publications
PURPOSE: Pulmonary benign metastasizing leiomyoma (PBML), a rare condition of smooth muscle tumor, originates from women with a history of uterine leiomyoma (LM). Numerous genetic studies of uterine LM have been reported; however, there are few cytogenetic and molecular descriptions of PBML. Therefore, molecular subtyping is necessary to understand the pathogenesis of metastasizing sites.
METHODS: Driver gene exon-capture sequencing was performed on one patient's peripheral blood, paraffin samples from primary uterine LM, and lung metastasizing leiomyoma 8 years later.
RESULTS: The results showed that the same missense mutations of BLMH, LRP2, MED12, SMAD2, and UGT1A8 were concurrently mutated in the primary uterine LM and the PBML. Moreover, a splice mutation of PTEN (c.492+1G>A) was uniquely identified in the lung metastasis of the patient.
CONCLUSION: This study indicates that the metastatic lung lesions were derived from the same malignant cell clone of uterine LMs and later acquired the novel driver mutations in the evolution of the tumor. In addition, driver gene sequencing can discriminate somatic driver mutations as biological indicators of potential malignant leiomyoma and can identify pathogenic variation driver mutations, which could be used for individualized therapy.

Park MJ, Shen H, Spaeth JM, et al.
Oncogenic exon 2 mutations in Mediator subunit MED12 disrupt allosteric activation of cyclin C-CDK8/19.
J Biol Chem. 2018; 293(13):4870-4882 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Somatic mutations in exon 2 of the RNA polymerase II transcriptional Mediator subunit

Tan BY, Tan PH
A Diagnostic Approach to Fibroepithelial Breast Lesions.
Surg Pathol Clin. 2018; 11(1):17-42 [PubMed] Related Publications
Fibroepithelial breast lesions encompass a heterogeneous group of neoplasms that range from benign to malignant, each exhibiting differing degrees of stromal proliferation in relation to the epithelial compartment. Fibroadenomas are common benign neoplasms that may be treated conservatively. Phyllodes tumors are relatively rare lesions, and classified as benign, borderline, or malignant based on histologic evaluation of various parameters. The diagnostic interpretation of "gray-zone" fibroepithelial lesions often imposes formidable demands on a pathologist's skills. This article offers practical recommendations for the diagnostic workup of these lesions, including the appropriate utilization of ancillary investigations and the approach to core needle biopsies.

Lee M, Cheon K, Chae B, et al.
Analysis of
Int J Med Sci. 2018; 15(2):124-128 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Uterine leiomyomas are one of the most common benign gynecologic tumors, but the exact causes are not completely understood. In 2011, through DNA sequencing,

Garcia-Dios DA, Levi D, Shah V, et al.
MED12, TERT promoter and RBM15 mutations in primary and recurrent phyllodes tumours.
Br J Cancer. 2018; 118(2):277-284 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
BACKGROUND: MED12 and TERT promoter mutations have been shown to be the most common somatic mutations in phyllodes tumours (PTs). The aims of this study were to determine the frequency of these mutations in recurrent PTs, assess whether TERT promoter mutations could be helpful in distinguishing fibroadenomas (FAs) from PTs and identify novel mutations that may be driving malignant progression.
METHODS: MED12 and the TERT promoter were Sanger sequenced in 75 primary PTs, 21 recurrences, 19 single FAs and 2 cases of multiple FAs with benign PTs. Whole-exome sequencing was performed on one borderline PT.
RESULTS: Recurrent PTs and multiple FAs showed temporal discordance in MED12 but not TERT. Recurrent samples did acquire TERT mutations, with recurrent benign PTs more likely to have mutations in both genes. TERT mutations were not helpful in differentiating between benign PTs and FAs in cases of multiple FAs/PTs. Exome sequencing revealed a nonsense mutation in RBM15 and Sanger sequencing revealed another three RBM15 mutations in malignant/borderline PTs.
CONCLUSIONS: This study has shown that MED12 mutations can be heterogeneous in both synchronous and recurrent PTs unlike TERT mutations. We have also shown that RBM15 mutations may be important in the pathogenesis of borderline/malignant PTs.

Rubin MA, Demichelis F
The Genomics of Prostate Cancer: emerging understanding with technologic advances.
Mod Pathol. 2018; 31(S1):S1-11 [PubMed] Related Publications
With the advent of next-generation sequencing technologies and large whole-exome and genome studies in prostate and other cancers, our understanding of the landscape of genomic alterations has dramatically been refined. In additional to well-known alterations in genomic regions involving 8p, 8q, 10q23, common ETS translocations and androgen receptor amplifications, newer technology have uncovered recurrent mutations in SPOP, FOXA1, MED12, IDH and complex large scale genomic alterations (eg, chromoplexy). This review surveys the enhanced landscape of genomic alterations in clinically localized and advanced prostate cancer.

Loke BN, Md Nasir ND, Thike AA, et al.
Genetics and genomics of breast fibroadenomas.
J Clin Pathol. 2018; 71(5):381-387 [PubMed] Related Publications
Fibroadenomas of the breast are benign fibroepithelial tumours most frequently encountered in women of reproductive age, although they may be diagnosed at any age. The fibroadenoma comprises a proliferation of both stromal and epithelial components. The mechanisms underlying fibroadenoma pathogenesis remain incompletely understood. In the clinical setting, distinguishing cellular fibroadenomas from benign phyllodes tumours is a common diagnostic challenge due to subjective histopathological criteria and interobserver differences. Recent sequencing studies have demonstrated the presence of highly recurrent mutations in fibroadenomas, and also delineated the genomic landscapes of fibroadenomas and the closely related phyllodes tumours, revealing differences at the gene level, which may be of potential adjunctive diagnostic use. The present article provides an overview of key studies uncovering genetic and genomic abnormalities in fibroadenomas, from initial karyotype reports revealing myriad cytogenetic aberrations to next-generation sequencing-based approaches that led to the discovery of highly recurrent

Jamaluddin MFB, Ko YA, Kumar M, et al.
Proteomic Profiling of Human Uterine Fibroids Reveals Upregulation of the Extracellular Matrix Protein Periostin.
Endocrinology. 2018; 159(2):1106-1118 [PubMed] Related Publications
The central characteristic of uterine fibroids is excessive deposition of extracellular matrix (ECM), which contributes to fibroid growth and bulk-type symptoms. Despite this, very little is known about patterns of ECM protein expression in fibroids and whether these are influenced by the most common genetic anomalies, which relate to MED12. We performed extensive genetic and proteomic analyses of clinically annotated fibroids and adjacent normal myometrium to identify the composition and expression patterns of ECM proteins in MED12 mutation-positive and mutation-negative uterine fibroids. Genetic sequencing of tissue samples revealed MED12 alterations in 39 of 65 fibroids (60%) from 14 patients. Using isobaric tagged-based quantitative mass spectrometry on three selected patients (n = 9 fibroids), we observed a common set of upregulated (>1.5-fold) and downregulated (<0.66-fold) proteins in small, medium, and large fibroid samples of annotated MED12 status. These two sets of upregulated and downregulated proteins were the same in all patients, regardless of variations in fibroid size and MED12 status. We then focused on one of the significant upregulated ECM proteins and confirmed the differential expression of periostin using western blotting and immunohistochemical analysis. 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. This study sets the foundation for further investigations to analyze the mechanisms regulating ECM overexpression and the functional role of upregulated ECM proteins in leiomyogenesis.

Weber H, Garabedian MJ
The mediator complex in genomic and non-genomic signaling in cancer.
Steroids. 2018; 133:8-14 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Mediator is a conserved, multi-subunit macromolecular machine divided structurally into head, middle, and tail modules, along with a transiently associating kinase module. Mediator functions as an integrator of transcriptional regulatory activity by interacting with DNA-bound transcription factors and with RNA polymerase II (Pol II) to both activate and repress gene expression. Mediator has been shown to affect multiple steps in transcription, including chromatin looping between enhancers and promoters, pre-initiation complex formation, transcriptional elongation, and mRNA splicing. Individual Mediator subunits participate in regulation of gene expression by the estrogen and androgen receptors and are altered in a number of endocrine cancers, including breast and prostate cancer. In addition to its role in genomic signaling, MED12 has been implicated in non-genomic signaling by interacting with and activating TGF-beta receptor 2 in the cytoplasm. Recent structural studies have revealed extensive inter-domain interactions and complex architecture of the Mediator-Pol II complex, suggesting that Mediator is capable of reorganizing its conformation and composition to fit cellular needs. We propose that alterations in Mediator subunit expression that occur in various cancers could impact the organization and function of Mediator, resulting in changes in gene expression that promote malignancy. A better understanding of the role of Mediator in cancer could reveal new approaches to the diagnosis and treatment of Mediator-dependent endocrine cancers, especially in settings of therapy resistance.

Heinonen HR, Mehine M, Mäkinen N, et al.
Global metabolomic profiling of uterine leiomyomas.
Br J Cancer. 2017; 117(12):1855-1864 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
BACKGROUND: Uterine leiomyomas can be classified into molecularly distinct subtypes according to their genetic triggers: MED12 mutations, HMGA2 upregulation, or inactivation of FH. The aim of this study was to identify metabolites and metabolic pathways that are dysregulated in different subtypes of leiomyomas.
METHODS: We performed global metabolomic profiling of 25 uterine leiomyomas and 17 corresponding myometrium specimens using liquid chromatography-tandem mass spectroscopy.
RESULTS: A total of 641 metabolites were detected. All leiomyomas displayed reduced homocarnosine and haeme metabolite levels. We identified a clearly distinct metabolomic profile for leiomyomas of the FH subtype, characterised by metabolic alterations in the tricarboxylic acid cycle and pentose phosphate pathways, and increased levels of multiple lipids and amino acids. Several metabolites were uniquely elevated in leiomyomas of the FH subtype, including N6-succinyladenosine and argininosuccinate, serving as potential biomarkers for FH deficiency. In contrast, leiomyomas of the MED12 subtype displayed reduced levels of vitamin A, multiple membrane lipids and amino acids, and dysregulation of vitamin C metabolism, a finding which was also compatible with gene expression data.
CONCLUSIONS: The study reveals the metabolomic heterogeneity of leiomyomas and provides the requisite framework for strategies designed to target metabolic alterations promoting the growth of these prevalent tumours.

Disclaimer: This site is for educational purposes only; it can not be used in diagnosis or treatment.

Cite this page: Cotterill SJ. MED12, Cancer Genetics Web: Accessed:

Creative Commons License
This page in Cancer Genetics Web by Simon Cotterill is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Note: content of abstracts copyright of respective publishers - seek permission where appropriate.

 [Home]    Page last revised: 29 August, 2019     Cancer Genetics Web, Established 1999