MED12 mutation frequency in unselected sporadic uterine leiomyomas

Pathogenesis of uterine fibroids: current understanding and future directions

Fibroids are benign uterine tumors characterized by the proliferation of uterine smooth muscle cells, embedded in an abundant extracellular matrix. Their prevalence is estimated to be >50% in women aged >45 years. Fibroids represent a considerable health burden. It is time to acquire a deeper mechanistic understanding of uterine fibroid-related etiology and pathogenesis, which may help pinpoint new strategies and an individualized approach. There is a need to gather prospective data and conduct studies to compare alternative approaches and assess long-term outcomes with respect to quality of life, recurrence of symptoms (bleeding and bulk symptoms), fertility, and even complications The goal of this review was to evaluate the widely accepted pathogenesis and identify risks factors and future directions for clinical and basic research into fibroids.

Periostin's role in uterine leiomyoma development: a mini-review on the potential periostin poses as a pharmacological intervention for uterine leiomyoma

Uterine leiomyomas, also known as fibroids or myomas, occur in an estimated 70-80% of reproductive aged women. Many experience debilitating symptoms including pelvic pain, abnormal uterine bleeding (AUB), dyspareunia, dysmenorrhea, and infertility. Current treatment options are limited in preserving fertility, with many opting for sterilizing hysterectomy as a form of treatment. Currently, surgical interventions include hysterectomy, myomectomy, and uterine artery embolization in addition to endometrial ablation to control AUB. Non-surgical hormonal interventions, including GnRH agonists, are connotated with negative side effects and are unacceptable for women desiring fertility. Periostin, a regulatory extra cellular matrix (ECM) protein, has been found to be expressed in various gynecological diseases including leiomyomas. We previously determined that periostin over-expression in immortalized myometrial cells led to the development of a leiomyoma-like cellular phenotype. Periostin is induced by TGF-β, signals through the PI3K/AKT pathway, induces collagen production, and mediates wound repair and fibrosis, all of which are implicated in leiomyoma pathology. Periostin has been linked to other gynecological diseases including ovarian cancer and endometriosis and is being investigated as pharmacological target for treating ovarian cancer, post-surgical scarring, and numerous other fibrotic conditions. In this review, we provide discussion linking pathological inflammation and wound repair, with a TGF-β-periostin-collagen signaling in the pathogenesis of leiomyomas, and ultimately the potential of periostin as a druggable target to treat leiomyomas.

A prospective ultrasound study of cigarette smoking and uterine leiomyomata incidence and growth

BACKGROUND

Uterine leiomyomata (fibroids) are common, benign neoplasms that contribute substantially to gynecologic morbidity. Some existing epidemiologic studies indicate that cigarette smoking is associated with lower uterine leiomyomata risk. However, no prospective studies have systematically screened an entire study population for uterine leiomyomata using transvaginal ultrasound or evaluated the association between cigarette smoking and uterine leiomyomata growth.

OBJECTIVE

This study aimed to examine the association between cigarette smoking and uterine leiomyomata incidence and growth in a prospective ultrasound study.

STUDY DESIGN

We enrolled 1693 residents from the Detroit metropolitan area into the Study of Environment, Lifestyle, and Fibroids during 2010 to 2012. Eligible participants were aged 23 to 34 years, had an intact uterus but no previous diagnosis of uterine leiomyomata, and self-identified as Black or African American. We invited participants to complete a baseline visit and 4 follow-up visits over approximately 10 years. At each visit, we used transvaginal ultrasound to assess uterine leiomyomata incidence and growth. Participants provided extensive self-reported data throughout follow-up including exposures to active and passive cigarette smoking in adulthood. We excluded participants who did not return for any follow-up visits (n=76; 4%). We fit Cox proportional hazards regression models to estimate hazard ratios and 95% confidence intervals for the association between time-varying smoking history and incidence rates of uterine leiomyomata. We fit linear mixed models to estimate the percentage difference and 95% confidence intervals for the association between smoking history and uterine leiomyomata growth. We adjusted for sociodemographic, lifestyle, and reproductive factors. We interpreted our results based on magnitude and precision rather than binary significance testing.

RESULTS

Among 1252 participants without ultrasound evidence of uterine leiomyomata at baseline, uterine leiomyomata were detected in 394 participants (31%) during follow-up. Current cigarette smoking was associated with a lower uterine leiomyomata incidence rate (hazard ratio, 0.67; 95% confidence interval, 0.49-0.92). Associations were stronger among participants who had smoked for longer durations (≥15 years vs never: hazard ratio, 0.49; 95% confidence interval, 0.25-0.95). The hazard ratio for former smokers was 0.78 (95% confidence interval, 0.50-1.20). Among never smokers, the hazard ratio for current passive smoke exposure was 0.84 (95% confidence interval, 0.65-1.07). Uterine leiomyomata growth was not appreciably associated with current (percent difference, -3%; 95% confidence interval, -13% to 8%) or former (percent difference, -9%; 95% confidence interval, -22% to 6%) smoking.

CONCLUSION

We provide evidence from a prospective ultrasound study that cigarette smoking is associated with lower uterine leiomyomata incidence.

The Effects of Periostin Expression on Fibroid-Like Transition of Myometrial Cells

Fibroids, benign tumors of the myometrium, are the most common tumors in women and are associated with spontaneous abortion, preterm birth, placenta abruption, and infertility, among others. The incidence of fibroids in reproductive aged women is 20-89%. Fibroids are characterized by high production of extracellular matrix (ECM), particularly collagens, which play a role in their growth. However, their pathogenesis is poorly understood. Recently, we and others have found periostin (POSTN), a regulatory ECM protein, to be overexpressed in the majority of fibroids analyzed. Periostin is an ECM protein that is a critical regulator and well-established biomarker for fibrosis in tissues such as the lung, skin, and kidney. Our hypothesis was that periostin plays a role in the fibrotic transition of myometrial cells to fibroid cells. To test this, we evaluated the effects of POSTN overexpression in myometrial cells. Telomerase-immortalized myometrial cells were transduced with control or POSTN-overexpression lentivirus particles, generating one control (dCas9-Mock) and two overexpression (dCas9-POSTN-01, dCas9-POSTN-02) cell lines. Overexpression of POSTN in immortalized myometrial cells resulted in a change in phenotype consistent with fibroid cells. They upregulated expression of key fibroid genes and had increased proliferation, adhesion, and migration in vitro. Here, we show a potential role for periostin in the transition of myometrial cells to fibroid cells, giving rationale for future investigation into the role of periostin in fibroid pathogenesis and its potential as a therapeutic target.

A View on Uterine Leiomyoma Genesis through the Prism of Genetic, Epigenetic and Cellular Heterogeneity

Uterine leiomyomas (ULs), frequent benign tumours of the female reproductive tract, are associated with a range of symptoms and significant morbidity. Despite extensive research, there is no consensus on essential points of UL initiation and development. The main reason for this is a pronounced inter- and intratumoral heterogeneity resulting from diverse and complicated mechanisms underlying UL pathobiology. In this review, we comprehensively analyse risk and protective factors for UL development, UL cellular composition, hormonal and paracrine signalling, epigenetic regulation and genetic abnormalities. We conclude the need to carefully update the concept of UL genesis in light of the current data. Staying within the framework of the existing hypotheses, we introduce a possible timeline for UL development and the associated key events—from potential prerequisites to the beginning of UL formation and the onset of driver and passenger changes.

Inherited mutations affecting the SRCAP complex are central in moderate-penetrance predisposition to uterine leiomyomas

Uterine leiomyomas (ULs) are benign smooth muscle tumors that are common in premenopausal women. Somatic alterations in MED12, HMGA2, FH, genes encoding subunits of the SRCAP complex, and genes involved in Cullin 3-RING E3 ligase neddylation are mutually exclusive UL drivers. Established predisposition genes explain only partially the estimated heritability of leiomyomas. Here, we examined loss-of-function variants across 18,899 genes in a cohort of 233,614 White European women, revealing variants in four genes encoding SRCAP complex subunits (YEATS4, ZNHIT1, DMAP1, and ACTL6A) with a significant association to ULs, and YEATS4 and ZNHIT1 strikingly rank first and second, respectively. Positive mutation status was also associated with younger age at diagnosis and hysterectomy. Moderate-penetrance UL risk was largely attributed to rare non-synonymous mutations affecting the SRCAP complex. To examine this disease phenotype more closely, we set out to identify inherited mutations affecting the SRCAP complex in our in-house sample collection of Finnish individuals with ULs (n = 860). We detected one individual with an ACTL6A splice-site mutation, two individuals with a YEATS4 missense mutation, and four individuals with DMAP1 mutations: one splice-site, one nonsense, and two missense variants. These individuals had large and/or multiple ULs, were often diagnosed at an early age, and many had family history of ULs. When a somatic second hit was found, ACTL6A and DMAP1 were silenced in tumors by somatic mutation and YEATS4 by promoter hypermethylation. Decreased H2A.Z staining was observed in the tumors, providing further evidence for the pathogenic nature of the germline mutations. Our results establish inactivation of genes encoding SRCAP complex subunits as a central contributor to moderate-penetrance UL predisposition.

MED12 mutations in uterine leiomyomas: prediction of volume reduction by gonadotropin-releasing hormone agonists

BACKGROUND

Gonadotropin-releasing hormone agonists are used to treat premenopausal uterine leiomyomas; however, leiomyoma volume reduction is not always achieved. The reduction rate after this treatment varies for each leiomyoma, even in the same patient. Therefore, an effective method for predicting uterine leiomyoma volume reduction is required to reduce the adverse hypoestrogenic effects and drug-related economic burden related to gonadotropin-releasing hormone agonists.

OBJECTIVE

This study aimed to determine the predictive use of MED12 mutations for evaluating the effect of gonadotropin-releasing hormone agonist treatment concerning reducing uterine leiomyoma volume and to predict the MED12 mutation status based on the findings of magnetic resonance imaging performed before treatment.

STUDY DESIGN

MED12 exon 2 mutation and erythropoietin expression in uterine leiomyomas were evaluated concerning volume reduction, as measured using magnetic resonance imaging. We developed a system for classifying leiomyomas according to T2-weighted magnetic resonance imaging signals to noninvasively predict the presence or absence of MED12 mutations in leiomyomas. Leiomyoma samples (>5 cm) were obtained from 168 patients during surgery (hysterectomy or myomectomy) between 2005 and 2021 at Yokohama City University Hospital. To analyze the rate of leiomyoma volume reduction, 41 patients had been preoperatively administered the gonadotropin-releasing hormone agonist (leuprorelin acetate 3.75 mg, monthly subcutaneous injection) for 3 months; magnetic resonance imaging was performed before and after treatment without contrast material.

RESULTS

Patients with MED12 exon 2 mutations had smaller volume reduction after treatment with the gonadotropin-releasing hormone agonist (P<.001, Mann-Whitney U test) and displayed lower signal intensity on T2-weighted images than those with leiomyomas expressing wild-type MED12 exon 2. The newly proposed magnetic resonance imaging-based classification system showed that MED12 exon 2 mutations were more frequent in the low-signal group than in the high-signal group, with nearly equal proportions of mutated and wild-type MED12 exon 2 leiomyomas noted in the intermediate group. The low-signal group had significantly lower erythropoietin expression levels than the high-signal group (P<.001, Kruskal-Wallis test with the Dunn posthoc analysis).

CONCLUSION

MED12 mutation status can be a candidate marker for predicting the effect of gonadotropin-releasing hormone agonists on uterine leiomyoma reduction. Magnetic resonance imaging findings can be used to determine MED12 mutation status as a noninvasive strategy to select patients who will most likely benefit from gonadotropin-releasing hormone agonist treatment.

Comprehensive Review of Uterine Fibroids: Developmental Origin, Pathogenesis, and Treatment

Uterine fibroids are benign monoclonal neoplasms of the myometrium, representing the most common tumors in women worldwide. To date, no long-term or noninvasive treatment option exists for hormone-dependent uterine fibroids, due to the limited knowledge about the molecular mechanisms underlying the initiation and development of uterine fibroids. This paper comprehensively summarizes the recent research advances on uterine fibroids, focusing on risk factors, development origin, pathogenetic mechanisms, and treatment options. Additionally, we describe the current treatment interventions for uterine fibroids. Finally, future perspectives on uterine fibroids studies are summarized. Deeper mechanistic insights into tumor etiology and the complexity of uterine fibroids can contribute to the progress of newer targeted therapies.

Guizhi Fuling Capsule inhibits uterine fibroids growth by modulating Med12-mediated Wnt/β-Catenin signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Guizhi Fuling Capsule (GFC) is a famous traditional Chinese medicine (TCM) formula recorded in Synopsis of the Golden Chamber, which has achieved obvious effects in the treatment of uterine fibroids (UFs).

AIM OF STUDY

Mediator complex subunit 12 (Med12) mutations were closely related to UFs in 85% of fibroid cases. The Wnt/β-Catenin signaling pathway plays an important role in the occurrence and development of UFs. This study aims to explore the pharmacological mechanism of GFC against UFs in which the Med12-mediated Wnt/β-Catenin pathway is involved.

MATERIALS AND METHODS

Med12 was silenced in uterine fibroid cells (UFCs) using a lentivirus-based Med12 gene-specific RNA interference (RNAi) strategy. Cell proliferation was performed by CCK-8 assay, cell apoptosis and cell cycle were measured by flow cytometry. The rat model of UFs was established by injecting estradiol benzoate and progesterone. Forty-eight rats were divided into six groups, the low-dose GFC (L-GFC) group, the medium-dose GFC (M-GFC) group and the high-dose GFC (H-GFC) group were intragastrically treated with GFC solution at 0.25 g/kg, 0.50 g/kg and 1.00 g/kg per day for 8 weeks, the positive control (PC) group was administrated with mifepristone (2.70 mg/kg/day), the normal control (NC) group and the model control (MC) group were given equal volume of normal saline once a day for 8 weeks. The histopathological changes of uterine tissues were evaluated by H&E staining. The expression of Med12 in uterine tissues were detected by immunohistochemistry. The protein and mRNA levels of associated genes were evaluated by western bolt and real time-PCR, respectively. Related indicators involved in Wnt/β-Catenin pathway, such as Wnt1, β-Catenin, Cyclin D1, TCF1/TCF7 and C-myc, were compared among different groups.

RESULTS

The Wnt/β-Catenin signaling pathway was inhibited after Med12 gene was knocked out in UFCs. GFC-containing serum could induce cell apoptosis, make the cell cycle stagnated in G0/G1 phase to inhibiting the proliferation and reduce the expression of Wnt1, β-Catenin, Cyclin D1, TCF1/TCF7, and C-myc in control-shRNA cells, while had no significant effect on Med12-shRNA cells. Compared with the MC group, the weight, endometrial thickness, and pathological structure of the uterus in the GFC treated groups were significantly improved. The expression of Med12, Wnt1, β-Catenin, Cyclin D1, TCF1/TCF7, and C-myc that related to Wnt/β-Catenin pathway in the GFC treated groups were decreased with the increase of dosage administration.

CONCLUSIONS

GFC inhibited UFs growth, which was directly associated with Med12 modulated Wnt/β-Catenin signaling pathway. This study provided new perspective to understand the therapeutic mechanism of UFs.

Comparison of 2SC, AKR1B10, and FH Antibodies as Potential Biomarkers for FH-deficient Uterine Leiomyomas

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a tumor predisposition syndrome caused by germline fumarate hydratase (FH) mutations and characterized by uterine and cutaneous leiomyomas and renal cell cancer. Currently, there is no generally approved method to differentiate FH-deficient uterine leiomyomas from other leiomyomas. Here, we analyzed 3 antibodies (S-(2-succino)-cysteine [2SC], aldo-keto reductase family 1, member B10 [AKR1B10], and FH) as potential biomarkers. The study consisted of 2 sample series. The first series included 155 formalin-fixed paraffin-embedded uterine leiomyomas, of which 90 were from HLRCC patients and 65 were sporadic. The second series included 1590 unselected fresh frozen leiomyomas. Twenty-seven tumors were from known HLRCC patients, while the FH status for the remaining 1563 tumors has been determined by copy number analysis and Sanger sequencing revealing 45 tumors with monoallelic (n=33) or biallelic (n=12) FH loss. Altogether 197 samples were included in immunohistochemical analyses: all 155 samples from series 1 and 42 available corresponding formalin-fixed paraffin-embedded samples from series 2 (15 tumors with monoallelic and 7 with biallelic FH loss, 20 with no FH deletion). Results show that 2SC performed best with 100% sensitivity and specificity. Scoring was straightforward with unambiguously positive or negative results. AKR1B10 identified most tumors accurately with 100% sensitivity and 99% specificity. FH was 100% specific but showed slightly reduced 91% sensitivity. Both FH and AKR1B10 displayed also intermediate staining intensities. We suggest that when patient's medical history and/or histopathologic tumor characteristics indicate potential FH-deficiency, the tumor's FH status is determined by 2SC staining. When aberrant staining is observed, the patient can be directed to genetic counseling and mutation screening.

The role of mediator subunit 12 in tumorigenesis and cancer therapeutics (Review)

Mediator complex subunit 12 (MED12) is a subunit of Mediator, a large multi-subunit protein complex that acts an important regulator of transcription. Specifically, MED12 is an integral part of the kinase module of Mediator along with MED13, CyclinC (CycC) and CDK8. Structural studies have indicated that MED12 makes a direct connection to CycC through a specific interface and thereby functions to create a link between MED13 and CycC-CDK8. Disruption of the MED12-CycC interface often leads to dysregulated CDK8 kinase activity, which has important physiological implications. For example, a number of studies have indicated that mutations within MED12 can lead to the formation of benign or malignant tumors, either as a result of MED12-CycC disruption or through distinct independent mechanisms. Furthermore, recent studies have indicated that the N-terminal portion of MED12 forms a direct connection to CDK8. Mutations within MED12 do not appear to disrupt the physical connection to CDK8, but rather abrogate CDK8 kinase activity. Thus, mutations in MED12 can cause disruption of CDK8 kinase activity through two separate mechanisms. The aim of the present review article was to discuss the MED12 mutational landscape in a variety of benign and malignant tumors, as well as the mechanistic basis behind tumorigenesis. Furthermore, the link between MED12 and drug resistance has also been discussed, as well as potential cancer therapeutics related to MED12-altered tumors.

Long Noncoding RNA MIAT Modulates the Extracellular Matrix Deposition in Leiomyomas by Sponging MiR-29 Family

The objective of this study was to determine the expression and functional role of a long noncoding RNA (lncRNA) MIAT (myocardial infarction-associated transcript) in leiomyoma pathogenesis. Leiomyoma compared with myometrium (n = 66) expressed significantly more MIAT that was independent of race/ethnicity and menstrual cycle phase but dependent on MED12 (mediator complex subunit 12) mutation status. Leiomyomas bearing the MED12 mutation expressed higher levels of MIAT and lower levels of microRNA 29 family (miR-29a, -b, and -c) compared with MED12 wild-type leiomyomas. Using luciferase reporter activity and RNA immunoprecipitation analysis, MIAT was shown to sponge the miR-29 family. In a 3-dimensional spheroid culture system, transient transfection of MIAT siRNA in leiomyoma smooth muscle cell (LSMC) spheroids resulted in upregulation of miR-29 family and downregulation of miR-29 targets, collagen type I (COL1A1), collagen type III (COL3A1), and TGF-β3 (transforming growth factor β-3). Treatment of LSMC spheroids with TGF-β3 induced COL1A1, COL3A1, and MIAT levels, but repressed miR-29 family expression. Knockdown of MIAT in LSMC spheroids blocked the effects of TGF-β3 on the induction of COL1A1 and COL3A1 expression. Collectively, these results underscore the physiological significance of MIAT in extracellular matrix accumulation in leiomyoma.

Parity associates with chromosomal damage in uterine leiomyomas

Mechanical forces in a constrained cellular environment were recently established as a facilitator of chromosomal damage. Whether this could contribute to tumorigenesis is not known. Uterine leiomyomas are common neoplasms that display relatively few chromosomal aberrations. We hypothesized that if mechanical forces contribute to chromosomal damage, signs of this could be seen in uterine leiomyomas from parous women. We examined the karyotypes of 1946 tumors, and found a striking overrepresentation of chromosomal damage associated with parity. We then subjected myometrial cells to physiological forces similar to those encountered during pregnancy, and found this to cause DNA breaks and a DNA repair response. While mechanical forces acting in constrained cellular environments may thus contribute to neoplastic degeneration, and genesis of uterine leiomyoma, further studies are needed to prove possible causality of the observed association. No evidence for progression to malignancy was found.

Molecular and Cellular Insights into the Development of Uterine Fibroids

Uterine leiomyomas represent the most common benign gynecologic tumor. These hormone-dependent smooth-muscle formations occur with an estimated prevalence of ~70% among women of reproductive age and cause symptoms including pain, abnormal uterine bleeding, infertility, and recurrent abortion. Despite the prevalence and public health impact of uterine leiomyomas, available treatments remain limited. Among the potential causes of leiomyomas, early hormonal exposure during periods of development may result in developmental reprogramming via epigenetic changes that persist in adulthood, leading to disease onset or progression. Recent developments in unbiased high-throughput sequencing technology enable powerful approaches to detect driver mutations, yielding new insights into the genomic instability of leiomyomas. Current data also suggest that each leiomyoma originates from the clonal expansion of a single transformed somatic stem cell of the myometrium. In this review, we propose an integrated cellular and molecular view of the origins of leiomyomas, as well as paradigm-shifting studies that will lead to better understanding and the future development of non-surgical treatments for these highly frequent tumors.

Several Fusion Genes Identified in a Spermatic Cord Leiomyoma With Rearrangements of Chromosome Arms 3p and 21q

BACKGROUND/AIM

Benign smooth-muscle tumors, leiomyomas, occur in nearly every organ but are most common in the uterus. Whereas much is known about the genetics of uterine leiomyomas, little genetic information exists about leiomyomas of other organs. Here, we report and discuss the genetic findings in a para-testicular leiomyoma.

MATERIALS AND METHODS

Cytogenetic, array comparative genomic hybridization (aCGH) RNA sequencing, reverse-transcription polymerase chain reaction (RT- PCR), and Sanger sequencing analyses were performed on a leiomyoma of the spermatic cord removed from a 61-year-old man.

RESULTS

The karyotype was 48~50,XY,add(3) (p21),+4,+7,+8,+9,add(21)(q22)[cp9]/46,XY[2]. aCGH confirmed the trisomies and also detected multiple gains and losses from 3p and 21q. RNA sequencing detected the chimeras ARHGEF3-CACNA2D2, TRAK1-TIMP4, ITPR1- DT-NR2C2, CLASP2-IL17RD, ZNF621-LARS2, CNTN4- RHOA, and NR2C2-CFAP410. All chimeras were confirmed by RT-PCR and Sanger sequencing.

CONCLUSION

Our data, together with those previously published, indicate that a group of leiomyomas may be cytogenetically characterized by aberrations of 3p and the formation of fusion genes.

Systematic molecular and clinical analysis of uterine leiomyomas from fertile-aged women undergoing myomectomy

STUDY QUESTION

What are the distributions and associated clinical characteristics of mediator complex subunit 12 (MED12), high mobility group AT-hook 2 (HMGA2) and fumarate hydratase (FH) aberrations in uterine leiomyomas from fertile-aged myomectomy patients?

SUMMARY ANSWER

These driver mutations account for the majority (83%) of tumours in fertile-aged patients.

WHAT IS KNOWN ALREADY

Alterations affecting MED12, HMGA2 and FH account for 80-90% of uterine leiomyomas from middle-aged hysterectomy patients, while the molecular background of tumours from young myomectomy patients has not been systematically studied.

STUDY DESIGN, SIZE, DURATION

A retrospective series of 361 archival uterine leiomyoma samples from 234 women aged ≤45 years undergoing myomectomy in 2009-2014 was examined. Associations between the molecular data and detailed clinical information of the patients and tumours were analysed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

DNA was extracted from formalin-fixed paraffin-embedded samples and MED12 exons 1 and 2 were sequenced to identify mutations. Level of HMGA2 expression was evaluated by immunohistochemistry. Biallelic FH inactivation was analysed with 2-succinylcysteine staining, which is an indirect method of assessing FH deficiency. All patients' medical histories were reviewed, and clinical information of patients and tumours was combined with molecular data.

MAIN RESULTS AND THE ROLE OF CHANCE

The median age at operation was 34 years. The majority (58%) of patients were operated on for a single leiomyoma. Known driver mutations were identified in 83% of tumours (71% MED12; 9% HMGA2; 3% FH). In solitary leiomyomas, the MED12 mutation frequency was only 43%, and 29% were wild-type for all driver alterations. MED12 mutations were associated with multiple tumours, smaller tumour size and subserosal location.

LIMITATIONS, REASONS FOR CAUTION

Although comprehensive, the study is retrospective in nature and all samples have been collected for routine diagnostic purposes. The use of paraffin-embedded samples and immunohistochemistry may have led to an underestimation of mutations. Due to the limited sample size and rarity of especially FH-deficient leiomyomas, the data are partly descriptive.

WIDER IMPLICATIONS OF THE FINDINGS

The contribution of driver mutations in leiomyomas from young myomectomy patients is comparable to tumours obtained from hysterectomies of mostly middle-aged women. Our results support the earlier findings that MED12 mutations are associated with multiple tumours, smaller tumour size and subserosal location. The study emphasizes the distinct molecular background of solitary leiomyomas, and more research is needed to clarify the underlying causes of the notable proportion of wild-type leiomyomas.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the Academy of Finland (307773), the Sigrid Jusélius Foundation, the Cancer Foundation Finland and the iCAN Digital Precision Cancer Medicine Flagship. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Frequency of MED12 Mutation in Relation to Tumor and Patient's Clinical Characteristics: a Meta-analysis

Mediator complex subunit 12 (MED12) is the most frequently mutated gene in uterine leiomyomas (ULs)-with a frequency of up to 85%-suggesting that it plays key roles in the pathogenesis of ULs. However, there is no established relationship between genetic alteration and other risk factors of UL pathogenesis such as the patient's age, weight, and race. In this meta-analysis, we established an association between these risk factors and the frequency of MED12 mutation. We also established the relationship between MED12 mutation with the number and size of tumors in a patient. A systematic literature search was performed for studies published by May 2020 and performed a meta-analysis according to PRISMA guidelines. Twenty-five studies were included in the analysis, representing 3151 tissue samples. MED12 mutations were more common in Black (74.5%) as compared to White (65.8%) and Asian (53.2%) patients. There was no significant relationship between the patient's age and the frequency of mutations (OR 0.73, 95% CI 0.38 to 1.41). MED12 mutations were common in patients barring small-sized (OR 1.46, 95% CI 1.09 to 1.95) multiple (OR 0.39, 95% CI 0.17 to 0.92) tumors. For the patient's weight, studies were few and the outcome was not statistically significant. This meta-analysis provides valuable information on the relationship between the patient's clinical characteristics and frequency of MED12 mutation among patients barring ULs, which is relevant for understanding the pathogenesis of ULs.Protocol registration: The protocol was registered in PROSPERO with registration number CRD42019123439.

Detection of MED12 mutations in mesenchymal components of uterine adenomyomas

Adenomyoma of the uterus is a biphasic nodular lesion composed of a mesenchymal component with smooth muscle differentiation and a glandular epithelium. The neoplastic nature of uterine adenomyomas has been controversial because some are considered to be nodular adenomyosis. MED12 mutations are involved in the pathogenesis of uterine smooth muscle tumors (leiomyomas and leiomyosarcomas) and biphasic tumors of the breast (fibroadenomas and phyllodes tumor). To investigate the histogenesis of uterine adenomyomas, we performed pathological and genetic analyses, including Sanger sequencing of MED12. In total, 15 cases of uterine adenomyomas were retrieved and assessed for clinicopathological factors. Immunohistochemistry for smooth muscle actin, desmin, and CD10 was performed. Exon 2 of MED12 was Sanger sequenced using DNA obtained by macrodissection of the adenomyomas. For cases that were positive for somatic MED12 mutations, we next performed microdissection of the mesenchymal and epithelial components. The DNA extracted from each component was further analyzed for MED12 mutations. MED12 mutations were detected in two adenomyomas (2/15, 13%), all in a known hot spot (codon 44). In both lesions, MED12 mutations were detected in multiple spots of the mesenchymal component. The epithelial component did not harbor MED12 mutations. The relatively low frequency of MED12 mutations suggests that not all adenomyomas are leiomyomas with entrapped glands. However, the results of our study suggest that a subset of uterine adenomyomas are true mesenchymal neoplasms.

Vitamin D as an effective treatment in human uterine leiomyomas independent of mediator complex subunit 12 mutation

OBJECTIVE

To study whether vitamin D (VitD) inhibits cell proliferation and Wnt/β-catenin and transforming growth factor-β (TGFβ) signaling pathways in uterine leiomyomas independent of mediator complex subunit 12 (MED12) mutation status.

DESIGN

Prospective study comparing leiomyoma vs. myometrial tissues and human uterine leiomyoma primary (HULP) cells treated with or without VitD and analyzed by MED12 mutation status.

SETTING

Hospital and university laboratories.

PATIENT(S)

Women with uterine leiomyoma without any treatment (n = 37).

INTERVENTION(S)

Uterine leiomyoma and myometrium samples were collected from women undergoing surgery because of symptomatic leiomyoma pathology.

MAIN OUTCOME MEASURE(S)

Analysis of Wnt/β-catenin and TGFβ pathways and proliferation by quantitative real-time polymerase chain reaction in leiomyoma and myometrial tissue as well as in VitD-treated HULP cells analyzed by Sanger sequencing.

RESULTS

Sequencing data showed that 46% of leiomyomas presented MED12 mutation, whereas no mutations were detected in adjacent myometrium. Expression of Wnt/β-catenin and TGFβ pathway genes was significantly increased in MED12-mutated leiomyomas compared to matched myometrium; no significant differences were found in wild-type (WT) leiomyomas. In HULP cells, VitD significantly decreased PCNA expression of both MED12-mutated and WT groups. VitD treatment decreased WNT4 and β-catenin expression in both groups compared to controls, with significance for WNT4 expression in MED12-mutated samples. Similarly, VitD significantly inhibited TGFβ3 expression in cells from both groups. MMP9 expression also decreased.

CONCLUSION

Despite molecular differences between MED12-mutated and WT leiomyomas, VitD inhibited Wnt/β-catenin and TGFβ pathways in HULP cells, suggesting VitD as an effective treatment to reduce proliferation and extracellular matrix formation in different molecular subtypes of uterine leiomyomas.

Molecular differential diagnosis of uterine leiomyomas and leiomyosarcomas

Uterine leiomyomas (LM) and leiomyosarcomas (LMS) are considered biologically unrelated tumors due to their cytogenetic and molecular disparity. Yet, these tumors share morphological and molecular characteristics that cannot be differentiated through current clinical diagnostic tests, and thus cannot be definitively classified as benign or malignant until surgery. Newer approaches are needed for the identification of these tumors, as has been done for other tissues. The application of next generation sequencing enables the detection of new mutations that, when coupled to machine learning bioinformatic tools, advances our understanding of chromosomal instability. These approaches in the context of LM and LMS could allow the discovery of genetic variants and possible genomic markers. Additionally, the potential clinical utility of circulating cell-free tumor DNA could revolutionize the noninvasive detection and monitoring of these tumors. Here, we seek to provide a perspective on the molecular background of LM and LMS, recognizing their distinct molecular features that may lead to improved diagnosis and personalized treatments, which would have a measurable impact on women's reproductive health.

MED12 exon 2 mutation is uncommon in intravenous leiomyomatosis: clinicopathologic features and molecular study

Intravenous leiomyomatosis (IVL) is a rare neoplasm that is characterized by smooth muscle cell proliferation within venous vessels. The aim of this study is to investigate the clinicopathological features, immunophenotypes, and MED12 gene mutations in IVL. Nine cases of IVL from the Affiliated Hospital of Qingdao University were collected, and the clinicopathological features were reviewed. The immunohistochemical expressions of p16, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), alpha thalassemia/mental retardation syndrome X-linked (ATRX), retinoblastoma 1 (RB1), fumarate hydratase (FH), and p53, were evaluated. The mutation status of MED12 gene exon 2 was detected by Sanger sequencing. All the 9 patients were women ranging from 32 to 58 years, and uterine leiomyomas were identified in 5 patients. Immunohistochemical staining showed that all IVL and leiomyoma samples were positive for estrogen receptor and progesterone receptor, but negative for CD34. IVL displayed similar immunostaining patterns with their uterine counterparts with focal p16 immunostaining. FH, PTEN, ATRX, and RB1 were variably positive, and p53 and Ki-67 positive rates were less than 5% in all cases. Two novel genetic variations at MED12 exon 2, a synonymous mutation c.141C>T (p.Asn47=), and an in-frame deletion mutation c.133_147del15 (p.Phe45_Pro49del) were identified in two IVL cases. One missense mutation c.131G>A (p.Gly44Asp) was identified in one uterine leiomyoma. The remaining 11 tumor samples (7 IVL cases and 4 uterine leiomyomas) showed no mutations at MED12 exon 2. Our results showed two novel MED12 mutations in IVL. The MED12 mutations are different between IVL and uterine leiomyoma. These findings indicate that IVL is a unique entity and different from uterine leiomyoma.

Introduction of Somatic Mutation in MED12 Induces Wnt4/β-Catenin and Disrupts Autophagy in Human Uterine Myometrial Cell

Uterine fibroids (UFs) or leiomyoma are frequently associated with somatic mutations in the mediator complex subunit 12 (MED12) gene; however, the function of these mutations in human UF biology is yet to be determined. Herein, we determined the functional role of the most common MED12 somatic mutation in the modulation of oncogenic Wnt4/β-catenin and mammalian target of rapamycin (mTOR) signaling pathways. Using an immortalized human uterine myometrial smooth muscle cell line (UtSM), we constitutively overexpressed either MED12-Wild Type or the most common MED12 somatic mutation (c.131G>A), and the effects of this MED12 mutation were compared between these cell lines. This immortalized cell line was used as a model because it expresses wild type MED12 protein and do not possess MED12 somatic mutations. By comparing the effect between MED12-WT and MED12-mutant (mut) stable cell populations, we observed increased levels of protein expression of Wnt4 and β-catenin in MED12-mut cells as compared with MED12-WT cells. MED12-mut cells also expressed increased levels of mTOR protein and oncogenic cyclin D1 which are hallmarks of cell growth and tumorigenicity. This somatic mutation in MED12 showed an effect on cell-cycle progression by induction of S-phase cells. MED12-mut cells also showed inhibition of autophagy as compared with MED12-WT cells. Together, these findings indicate that the MED12 somatic mutation has the potentials for myometrial cell transformation by dysregulating oncogenic Wnt4/β-catenin and its downstream mTOR signaling which might be associated with autophagy abrogation, cell proliferation, and tumorigenicity.

Intravenous leiomyomatosis: molecular analysis of 17 cases

Intravenous leiomyomatosis (IVL) is a rare smooth muscle tumour with a benign histology but with a quasi-malignant intravascular growth. In this study, we investigated the molecular alterations in 17 IVL cases composed of concurrent uterine leiomyoma (n=12), uterine IVL (n=17) and extra-uterine IVL (n=12). We found that eight tumours had a somatic MED12 mutation (c.130G>A, p.G44S, n=7; c.131G>C, p.G44A, n=1). The frequency of MED12 mutations was significantly higher in concurrent uterine leiomyoma (6/12, 50%) than in uterine (0/17, 0%) and extra-uterine IVL (2/12, 16.7%). The frequency of HMGA2 over-expression or MED12 low-expression was not significantly different among uterine leiomyoma, IVL and extra-uterine IVL (p>0.05). Short tandem repeat (STR) analysis indicated that one uterine and two extra-uterine IVL tumours from three patients were microsatellite instability positive (MSI+) whereas loss of heterozygosity (LOH) was found in one uterine leiomyoma, three uterine and three extra-uterine IVL tumours from five patients. LOH was more frequently seen in uterine/extra-uterine IVL tumours (6/20, 30%) than in the concurrent leiomyomas (1/7, 14.3%) (p<0.05). MED12 mutation, MSI and LOH were discordant between uterine and extra-uterine IVL in all patients. These findings suggest that IVL harbours distinct molecular pathogenesis from common uterine leiomyomas. Uterine IVL and extra-uterine tumours may represent an independent origin rather than uniclonal dissemination from a single tumour. Further investigations are warranted to explore the underlying key molecular events in the pathogenesis of IVL.

Ectopic expression of CYP24A1 circular RNA hsa_circ_0060927 in uterine leiomyomas

Background

As a novel class of non‐coding RNAs, the role of circular RNAs (circRNAs) in tumor biogenesis and progression has been proved in a number of human tumors; however, up to now, the relation between circRNAs and uterine leiomyomas (ULM) remains unclear.

Methods

In this study, we have estimated the expression level of CYP24A1 hsa_circ_0060927 in uterine leiomyoma and adjacent tissues considering the mediator complex subunit 12 gene (MED12) mutation profile by quantitative real‐time polymerase chain reaction (qRT‐PCRs).

Results

Using Sanger sequencing method, somatic mutations in the MED12 exon 2 were detected in 14 (35.90%) ULM samples, including 10 (71.43%) missense mutations and 4 (28.57%) in‐frame deletions. 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.

Conclusions

Present results provide primary evidence for the role of circular RNAs in the leiomyoma development; however, further studies are essential to confirm the importance of these molecules as potential biomarkers for diagnosis and/or prognosis in ULM.

LncRNA SRA1 may play a role in the uterine leiomyoma tumor growth regarding the MED12 mutation pattern

Background

Uterine leiomyomas (ULMs) are benign uterine tumors that are estrogen-dependent. Recent studies suggest that the abnormal expression of the steroid receptor RNA activator 1 (SRA1) long non-coding RNA (lncRNA) might participate in the mechanisms of tumorigenesis of some hormone-dependent tumors including breast cancer. SRA1 is known to enhance the transcriptional activity of steroid receptors and also promotes steroidogenesis. The level of steroid hormones, such as estrogen and the progesterone, and their receptors play an important role in the development and growth of leiomyoma. The aim of the present study was to determine the expression level of lncRNA SRA1 in ULM tissues considering the MED12 mutation pattern.

Methods

Mutation screening was performed for MED12 exons 1 and 2 and the intronic flanking regions using Sanger sequencing in 60 ULM tissues. Quantitative real-time polymerase chain reaction (qRT-PCRs) was performed in order to estimate the expression of lncRNA SRA1 in leiomyoma samples with and without MED12 gene mutations. The expression results were analyzed by using LinReg and REST software.

Results

Mutations were detected in exon 2 of the MED12 in 28 (46.67%) ULM samples; including, 21 (75%) missense mutations and 7 (25%) in-frame deletions. No mutation was detected in the MED12 exon 1. LncRNA SRA1 was over-expressed in ULM samples without MED12 mutation compared with ULM samples harboring MED12 mutation (Expression ratio=2.5, P-value=0.004).

Conclusion

Present results suggest that lncRNA SRA1 may explain the phenotypic difference observed in the tumor size of ULM samples considering MED12 mutation pattern. Therefore, it serves as a good therapeutic target and provides new insight into understanding the disease molecular mechanism.

Uterine stem cells: from basic research to advanced cell therapies

BACKGROUND

Stem cell research in the endometrium and myometrium from animal models and humans has led to the identification of endometrial/myometrial stem cells and their niches. This basic knowledge is beginning to be translated to clinical use for incurable uterine pathologies. Additionally, the implication of bone marrow-derived stem cells (BMDSCs) in uterine physiology has opened the field for the exploration of an exogenous and autologous source of stem cells.

OBJECTIVE AND RATIONALE

In this review, we outline the progress of endometrial and myometrial stem/progenitor cells in both human and mouse models from their characterization to their clinical application, indicating roles in Asherman syndrome, atrophic endometrium and tissue engineering, among others.

SEARCH METHODS

A comprehensive search of PubMed and Google Scholar up to December 2017 was conducted to identify peer-reviewed literature related to the contribution of bone marrow, endometrial and myometrial stem cells to potential physiological regeneration as well as their implications in pathologies of the human uterus.

OUTCOMES

The discovery and main characteristics of stem cells in the murine and human endometrium and myometrium are presented together with the relevance of their niches and cross-regulation. The current state of advanced stem cell therapy using BMDSCs in the treatment of Asherman syndrome and atrophic endometrium is analyzed. In the myometrium, the understanding of genetic and epigenetic defects that result in the development of tumor-initiating cells in the myometrial stem niche and thus contribute to the growth of uterine leiomyoma is also presented. Finally, recent advances in tissue engineering based on the creation of novel three-dimensional scaffolds or decellularisation open up new perspectives for the field of uterine transplantation.

WIDER IMPLICATIONS

More than a decade after their discovery, the knowledge of uterine stem cells and their niches is crystalising into novel therapeutic approaches aiming to treat with cells those conditions that cannot be cured with drugs, particularly the currently incurable uterine pathologies. Additional work and improvements are needed, but the basis has been formed for this therapeutic application of uterine cells.

Understanding Obesity as a Risk Factor for Uterine Tumors Using Drosophila

Multiple large-scale epidemiological studies have identified obesity as an important risk factor for a variety of human cancers, particularly cancers of the uterus, gallbladder, kidney, liver, colon, and ovary, but there is much uncertainty regarding how obesity increases the cancer risks. Given that obesity has been consistently identified as a major risk factor for uterine tumors, the most common malignancies of the female reproductive system, we use uterine tumors as a pathological context to survey the relevant literature and propose a novel hypothesis: chronic downregulation of the cyclin-dependent kinase 8 (CDK8) module, composed of CDK8 (or its paralog CDK19), Cyclin C, MED12 (or MED12L), and MED13 (or MED13L), by elevated insulin or insulin-like growth factor signaling in obese women may increase the chances to dysregulate the activities of transcription factors regulated by the CDK8 module, thereby increasing the risk of uterine tumors. Although we focus on endometrial cancer and uterine leiomyomas (or fibroids), two major forms of uterine tumors, our model may offer additional insights into how obesity increases the risk of other types of cancers and diseases. To illustrate the power of model organisms for studying human diseases, here we place more emphasis on the findings obtained from Drosophila melanogaster.

The Role of Tumor Necrosis Factor α in the Biology of Uterine Fibroids and the Related Symptoms

Uterine fibroids (UFs) are the most common benign tumors of the female genital tract. The incidence of UFs has been estimated at 25⁻80% depending on selected population. The pathophysiology of UFs remains poorly understood. The transformation of smooth muscle cells of the uterus into abnormal, immortal cells, capable of clonal division, is the main component of all pathways leading to UF tumor formation and tumor necrosis factor α (TNF-α) is believed to be one of the key factors in this field. TNF-α is a cell signaling protein involved in systemic inflammation and is one of the cytokines responsible for the acute phase reaction. This publication presents current data about the role of tumor necrosis factor α in the biology of UFs and the related symptoms. TNF-α is an extremely important cytokine associated with the biology of UFs, UF-related symptoms and complaints. Its concentration has been proven to be elevated in women with clinically symptomatic UFs. The presented data suggest the presence of an "inflammation-like" state in women with UFs where TNF-α is a potent inflammation inducer. The origin of numerous symptoms reported by women with UFs can be traced back to the TNF-α influence. Nevertheless, our knowledge on this subject remains limited and TNF-α dependent pathways in UF pathophysiology should be investigated further.

Genetic predisposition to uterine leiomyoma is determined by loci for genitourinary development and genome stability

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 TERT, TERC, OBFC1 - highlighting the role of telomere maintenance - TP53 and ATM. Genes involved in genitourinary development, WNT4, WT1, SALL1, MED12, ESR1, GREB1, FOXO1, DMRT1 and uterine stem cell marker antigen CD44, formed another strong subgroup. The combined risk contributed by the 22 loci was associated with MED12 mutation-positive tumors. The findings link genes for uterine development and genetic stability to leiomyomagenesis, and in part explain the more frequent occurrence of UL in women of African origin.

Fibroids – also known as uterine leiomyomas, or myomas – are a very common form of benign tumor that grows in the muscle wall of the uterus. As many as 70% of women develop fibroids in their lifetime. About a fifth of women report symptoms including severe pain, heavy bleeding during periods and complications in pregnancy. In the United States, the cost of treating fibroids is estimated to be $34 billion each year.

Despite the prevalence of fibroids in women, there are few treatments available. Drugs to target them have limited effect and often an invasive procedure such as surgery is needed to remove the tumors. However, a better understanding of the genetics of fibroids could lead to a way to develop better treatment options.

Välimäki, Kuisma et al. used a genome-wide association study to seek out DNA variations that are more common in people with fibroids. Using data from the UK Biobank, the genomes of over 15,000 women with fibroids were analyzed against a control population of over 392,000 individuals. The analysis revealed 22 regions of the genome that were associated with fibroids. These regions included genes that may well contribute to fibroid development, such as the gene TP53, which influences the stability of the genome, and ESR1, which codes for a receptor for estrogen – a hormone known to play a role in the growth of fibroids. Variation in a set of genes known to control development of the female reproductive organs was also identified in women with fibroids.

The findings are the result of the largest genome-wide association study on fibroids, revealing a set of genes that could influence the development of fibroids. Studying these genes could lead to more effective drug development to treat fibroids. Revealing this group of genes could also help to identify women at high risk of developing fibroids and help to prevent or manage the condition.

Management of a giant uterine leiomyoma

Uterine leiomyomas are the most common tumours arising from the female reproductive tract. However, giant myomas, which are greater than 11.4 kg in weight, are exceedingly rare. They may cause a pressure effect on surrounding organs, heart and lungs, which can be potentially life threatening. We present a case of a 53-year-old woman with a massive uterine mass complicated by restrictive lung disease. She underwent a total abdominal hysterectomy and bilateral salpingo-oophorectomy with frozen section and reconstruction of the abdominal wall by the gynaecologists and plastic surgeons. The excised specimen weighed 27.8 kg, which included a benign subserosal leiomyoma measuring 64 by 50.5 by 15 cm. Intraoperative blood loss was 7 L and her postoperative recovery was complicated by coagulopathy and haemorrhagic shock. This case illustrates the pivotal role of multidisciplinary care in the management of complicated surgical patients and the need for careful perioperative care.

Vitamin D and Uterine Fibroids-Review of the Literature and Novel Concepts

This article provides a detailed review of current knowledge on the role of vitamin D and its receptor in the biology and management of uterine fibroids (UFs). Authors present ideas for future steps in this area. A literature search was conducted in PubMed using the following key words: "uterine fibroid" and "vitamin D". The results of the available studies, published in English from January 2002 up to April 2018, have been discussed. Vitamin D is a group of steroid compounds with a powerful impact on many parts of the human body. This vitamin is believed to regulate cell proliferation and differentiation, inhibit angiogenesis, and stimulate apoptosis. Nowadays, hypovitaminosis D is believed to be a major risk factor in the development of UFs. In many studies vitamin D appears to be a powerful factor against UFs, resulting in inhibition of tumor cell division and a significant reduction in its size, however, the exact role of this compound and its receptor in the pathophysiology of UFs is not fully understood. According to available studies, vitamin D and its analogs seem to be promising, effective, and low-cost compounds in the management of UFs and their clinical symptoms, and the anti-tumor activities of vitamin D play an important role in UF biology. The synergy between vitamin D and selected anti-UF drugs is a very interesting issue which requires further research. Further studies about the biological effect of vitamin D on UF biology are essential. Vitamin D preparations (alone or as a co-drugs) could become new tools in the fight with UFs, with the additional beneficial pleiotropic effect.

MED12 is recurrently mutated in Middle Eastern colorectal cancer

OBJECTIVE

Colorectal cancer (CRC) is a common cancer and a leading cause of cancer deaths. Previous studies have identified a number of key steps in the evolution of CRC but our knowledge of driver mutations in CRC remains incomplete. Recognising the potential of studying different human populations to reveal novel insights in disease pathogenesis, we conducted genomic analysis of CRC in Saudi patients.

DESIGN

In the discovery phase of the study, we conducted whole genome sequencing of tumour and corresponding germline DNA in 27 patients with CRC. In addition to known driver mutations, we identified three MED12 somatic mutations. In the replication phase, we employed a next-generation sequencing approach to capture and sequence MED12 and other candidate genes in a larger sample of 400 patients with CRC and confirmed the enrichment for recurrent MED12 mutations.

RESULTS

In order to gain insight into a plausible biological mechanism for the potential role of MED12 mutations in CRC, we studied CRC cell lines that differ substantially in the expression level of MED12, and found the latter to be correlated inversely with transforming growth factor (TGF)-β signalling and directly with apoptosis in response to chemotherapeutic agents. Importantly, these correlations were replicated when MED12 expression was experimentally manipulated.

CONCLUSIONS

Our data expand the recently described role of MED12 as a tumour suppressor in other cancers to include CRC, and suggest TGF-β signalling as a potential mediator of this effect.

Factors affecting the loss of MED12-mutated leiomyoma cells during in vitro growth

Uterine leiomyomas (UL) are the most prevalent symptomatic human tumors at all and somatic mutations of the gene encoding mediator subcomplex 12 (MED12) constitute the most frequent driver mutations in UL. Recently, a rapid loss of mutated cells during in vitro growth of UL-derived cell cultures was reported, resulting in doubts about the benefits of UL-derived cell cultures. To evaluate if the rapid loss of MED12-mutated cells in UL cell cultures depends on in vitro passaging, we set up cell cultures from nine UL from 40–50 year old Caucasian patients with at least one UL. Cultured UL cells were investigated for loss of MED12-mutated cells. Genetic characterization of native tumor samples and adjacent myometrium was done by array analysis. “Aged” primary cultures without passaging were compared to cells of three subsequent passages. Comparative analyses of the mutated/non-mutated ratios between native tissue, primary cells, and cultured tumor cells revealed a clear decrease of MED12-mutated cells. None of the tumors showed gross alterations of the array profiles, excluding the presence of gross genomic imbalances besides the MED12 mutations as a reason for the intertumoral variation in the loss of MED12-mutated cells. 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. Identification of these factors can help to understand the mechanisms of the growth of the most frequent type of uterine leiomyomas and to decipher novel drug targets.

Analysis of MED12 Mutation in Multiple Uterine Leiomyomas in South Korean patients

Uterine leiomyomas are one of the most common benign gynecologic tumors, but the exact causes are not completely understood. In 2011, through DNA sequencing, MED12 mutation was discovered in approximately 71% of uterine leiomyomas. Several recent studies confirmed the high frequency of MED12 mutation in uterine leiomyoma. Nevertheless, no study has been done on MED12 mutation in the case of patients with multiple leiomyomas in a patient. The purpose of this study was to investigate the frequency of MED12 mutations in uterine leiomyomas of South Korean patients. In addition, we examined MED12 mutation in multiple leiomyomas in the same patients. Uterine leiomyoma tissues were obtained from symptomatic women who underwent hysterectomy or myomectomy for medically indicated reasons. We collected 60 uterine leiomyomas from 41 women. Tumor size ranged from 1 to 12cm. Patients' ages ranged from 25 to 55 years with an average of 38.4 years. Of the 60 tumors, 40 (66.67%) displayed MED12 mutation. Among the 41 patients, 14 patients had multiple leiomyomas and we analyzed those multiple leiomyomas. Three of them had the same mutations. Five of them, each leiomyoma had a different mutation. Two of them did not have mutation. Four of them had both mutation-positive and mutation-negative leiomyomas. In conclusion, we confirmed the high frequency of the MED12 mutation in uterine leiomyomas of South Korean patients. We also identified various MED12 mutation status in patients with multiple leiomyomas. This suggests that in a given patient, different tumors may have arisen from different cell origins and therefore it is supposed that occurrence of multiple leiomyoma in a single patient may not be caused by intrauterine metastasis or dissemination.

Alternative Oral Agents in Prophylaxis and Therapy of Uterine Fibroids-An Up-to-Date Review

Uterine fibroids (UFs) are the most common tumors of the female genital tract. The effect of UFs on the quality of life and the overall cost of treatment are significant issues worldwide. Tumor size and location are the two specific factors which influence the occurrence of symptoms, the need for, and method of, treatment (some tumors require surgery while some can be treated with selected drugs). Primary prevention and treatment of early UF disease are worthy goals that might have a great impact on health care systems. Several treatments and prophylactic methods can be used in this endeavor. This publication presents current data about lesser-known substances which may have a beneficial effect on the treatment or prophylaxis of UFs and can be administered orally, serving as an alternative to (or complement of) surgery or selective progesterone receptor modulators (SPRMs). Early prevention and treatment of UFs in women from high-risk groups should be our priority. Innovative forms of UF management are under intensive investigation and may be promising options in the near future. Many of them evaluated vitamin D, paricalcitol, epigallocatechin gallate (EGCG), elagolix, aromatase inhibitors (AIs), and cabergoline and deemed them to be safe and effective. The next step in such projects should be properly constructed randomized control trials (RCTs), carried out by successive phases.

Global metabolomic profiling of uterine leiomyomas

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.

Leiomyoma with bizarre nuclei: a morphological, immunohistochemical and molecular analysis of 31 cases

Leiomyomas associated with hereditary leiomyomatosis and renal cell carcinoma syndrome and leiomyomas with bizarre nuclei often show overlapping morphological features, in particular cells with prominent eosinophilic nucleoli, perinucleolar halos, and eosinophilic cytoplasmic inclusions. Although hereditary leiomyomatosis and renal cell carcinoma syndrome is defined by fumarate hydratase (FH) germline mutations, resulting in S-(2-succino)-cysteine (2SC) formation, it is unknown whether leiomyomas with bizarre nuclei show similar alterations. In this study, we evaluated the morphology and FH/2SC immunoprofile of 31 leiomyomas with bizarre nuclei. DNA from tumor and normal tissues from 24 cases was subjected to massively parallel sequencing targeting 410 key cancer genes. Somatic genetic alterations were detected using state-of-the-art bioinformatics algorithms. No patient reported a personal history of renal neoplasia or cutaneous leiomyomas, but one had a family history of renal cell carcinoma while another had a family history of uterine leiomyomas. Aberrant FH/2SC expression was noted in 17 tumors (16 FH-negative/2SC-positive, 1 FH-positive/2SC-positive). On univariate analysis, staghorn vessels, eosinophilic cytoplasmic inclusions, diffuse distribution of prominent eosinophilic nucleoli with perinucleolar halos, and an 'alveolar pattern of edema' were associated with an abnormal immunoprofile, but only staghorn vessels remained significant on multivariate analysis. Massively parallel sequencing analysis (n=24) revealed that 13/14 tumors with aberrant FH/2SC immunoprofile harbored somatic FH somatic genetic alterations, including homozygous deletions (n=9), missense mutations coupled with loss of heterozygosity (n=3), and a splice site mutation (n=1), whereas no somatic FH mutations/deletions were found in tumors with normal immunoprofile (n=10; P<0.0001). Leiomyomas with bizarre nuclei with normal FH/2SC staining pattern more frequently harbored TP53 and/or RB1 alterations than those with aberrant FH/2SC immunoprofile (60 vs 14%; P=0.032). These data demonstrate that leiomyomas with bizarre nuclei are morphologically and genetically heterogeneous and that hereditary leiomyomatosis and renal cell carcinoma syndrome-related morphological features, abnormal FH/2SC staining, and somatic FH mutations/deletions can be seen in a subset of sporadic tumors.

Prevalence and clinical significance of mediator complex subunit 12 mutations in 362 Han Chinese samples with uterine leiomyoma

Uterine leiomyomas (ULs) are the most common gynecological benign tumors originating from the myometrium. Prevalent mutations in the mediator complex subunit 12 (MED12) gene have been identified in ULs, and functional evidence has revealed that these mutations may promote the development of ULs. However, whether MED12 mutations are associated with certain clinical characteristics in ULs remains largely unknown. In the present study, the potential mutations of MED12 and its paralogous gene, mediator complex subunit 12-like (MED12L), were screened in 362 UL tumors from Han Chinese patients. A total of 158 out of 362 UL tumors (43.6%) were identified as harboring MED12 somatic mutations, and the majority of these mutations were restricted to the 44th residue. MED12 mutations were also observed in 2 out of 145 (1.4%) adjacent control myometrium. Furthermore, the mutation spectrum of MED12 in the concurrent leiomyomas was noticeably different. Correlation analysis of MED12 mutations with the available clinical features indicated that patients with mutated MED12 tended to have smaller cervical diameters. By contrast, no MED12L mutation was identified in the present samples. In summary, the present study demonstrated the presence of prevalent MED12 somatic mutations in UL samples, and the MED12 mutation was associated with smaller cervical diameters. The low mutation frequency of MED12 in adjacent control myometrium indicated that MED12 mutation may be an early event in the pathogenesis of ULs. Furthermore, MED12 mutation status in concurrent tumors from multiple leiomyomas supported several prior observations that the majority of these tumors arose independently.

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

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.

Frequency and Spectrum of MED12 Exon 2 Mutations in Multiple Versus Solitary Uterine Leiomyomas From Russian Patients

Uterine leiomyomas (ULs) are common benign tumors affecting women of different ethnicities. A large proportion of UL has mutations in MED12. Multiple and solitary ULs usually manifest with different severities, suggesting that their origin and growth pattern may be driven by different molecular mechanisms. Here, we compared the frequency and the spectrum of MED12 exon 2 mutations between multiple (n=82) and solitary (n=40) ULs from Russian patients. Overall, we detected MED12 exon 2 mutations in 51.6% (63/122) of ULs. The frequency of MED12 exon 2 mutations was almost two-fold higher in samples from the multiple UL patients than in those from the solitary UL patients - 61% (50/82) versus 32.5% (13/40). The increased MED12 exon 2 mutation frequency in the multiple ULs was not accompanied by significant alterations in the spectrum of mutation categories, which included missense mutations, deletions, splicing defects, and multiple (double/triple) mutations. Each mutation category had a unique mutation set, comprising both frequent and rarely encountered mutations, which did and did not overlap between the studied groups, respectively. We conclude that in contrast to the solitary ULs, the multiple ULs predominantly originate through MED12-associated mechanisms. The nature of these mechanisms seems to be similar in solitary and multiple ULs, as they contain similar mutations. In multiple UL patients, they are likely to be nonsporadic, indicating the existence of specific factors predisposing to multiple UL development. These data suggest that to clearly understand UL pathogenesis, solitary and multiple tumors should probably be analyzed as separate sets.

Silencing Med12 Gene Reduces Proliferation of Human Leiomyoma Cells Mediated via Wnt/β-Catenin Signaling Pathway

Uterine fibroids, or leiomyoma, are the most common benign tumors in women of reproductive age. In this work, the effect of silencing the mediator complex subunit 12 (Med12) gene in human uterine fibroid cells was evaluated. The role of Med12 in the modulation of Wnt/β-catenin and cell proliferation-associated signaling was evaluated in human uterine fibroid cells. Med12 was silenced in the immortalized human uterine fibroid cell line (HuLM) using a lentivirus-based Med12 gene-specific RNA interference strategy. HuLM cells were infected with lentiviruses carrying Med12-specific short hairpin RNA (shRNA) sequences or a nonfunctional shRNA scrambled control with green fluorescence protein. Stable cells that expressed low levels of Med12 protein were characterized. Wnt/β-catenin signaling, sex steroid receptor signaling, cell cycle-associated, and fibrosis-associated proteins were measured. Med12 knockdown cells showed significantly (P < 0.05) reduced levels of Wnt4 and β-catenin proteins as well as cell proliferation, as compared with scrambled control cells. Med12 knockdown cells also showed reduced levels of cell cycle-associated cyclin D1, Cdk1, and Cdk2 proteins as well as reduced activation of p-extracellular signal-regulated kinase, p-protein kinase B, and transforming growth factor (TGF)-β signaling pathways as compared with scrambled control cells. Moreover, TGF-β-regulated fibrosis-related proteins such as fibronectin, collagen type 1, and plasminogen activator inhibitor-1 were significantly (P < 0.05) reduced in Med12 knockdown cells as compared with scrambled control cells. Together, these results suggest that Med12 plays a key role in the regulation of HuLM cell proliferation through the modulation of Wnt/β-catenin, cell cycle-associated, and fibrosis-associated protein expression.

Catechol-O-methyltransferase Val158Met polymorphism is associated with increased risk of multiple uterine leiomyomas either positive or negative for MED12 exon 2 mutations

AIMS

To study the possible association of catechol-O-methyltransferase (COMT) Val158Met polymorphism with multiple and solitary uterine leiomyomas (ULs) and to check whether the COMT Val/Val genotype is associated with MED12 exon 2 mutations in fibroids.

METHODS

The COMT Val158Met allele and genotype frequencies were compared between age-matched women with ULs (n=104) and controls (n=59). Patients with UL were subcategorised by diagnosis of solitary (n=59) or multiple (n=45) fibroids and by the presence of somatic MED12 exon 2 mutations in at least one fibroid (n=32) or in neither fibroid (n=26). The association of COMT Val/Val genotype with the presence of any ULs, solitary/multiple ULs and ULs positive/negative for MED12 exon 2 mutations was evaluated by χ² tests using a dominant genotype model (G/G vs G/A+A/A) and expressed as ORs and 95% CIs.

RESULTS

The COMT Val/Val genotype frequency did not differ between the patients with UL and the controls (28.8% vs 18.6%, p=0.149, OR 1.77; CI 0.81 to 3.86). However, it was significantly higher in the patients who had multiple UL compared with the solitary UL (40% vs 20.3%, p=0.028, OR 2.61; CI 1.09 to 6.24) and to the controls (40% vs 18.6%, p=0.016, OR 2.91; CI 1.20 to 7.06). No association of the COMT Val/Val genotype with UL-specific MED12 exon 2 mutations was found (p=0.662, OR 0.77; CI 0.23 to 2.53).

CONCLUSIONS

Women with COMT Val/Val genotype are at high risk of developing multiple uterine fibroids either positive or negative for MED12 exon 2 mutations. These data are important to design new strategies for UL prophylaxis and treatment.

Endocrinology of uterine fibroids: steroid hormones, stem cells, and genetic contribution

PURPOSE OF REVIEW

Uterine fibroids are extremely common, and can cause significant morbidity, yet the exact cause of these tumors remains elusive and there are currently no long-term treatments available. In this review, we aim to provide an overview of steroid hormones, genetic abnormalities, and stem cells in the pathogenesis of uterine fibroids.

RECENT FINDINGS

A universal feature of fibroids is responsiveness to estrogen and progesterone, and most of the currently available therapies exploit this characteristic. Ulipristal acetate has recently shown particular promise for providing long-term relief from uterine fibroids. Additionally, fibroid stem cells were isolated and appear to be necessary for growth. The recent discovery of somatic mutations involving mediator subunit complex 12 (MED12) or high-mobility group AT-hook 2 (HMGA2) in the majority of fibroids and the links to their pathophysiology were also significant advances.

SUMMARY

The recent shift in focus from hormones to fibroid stem cells and genetic aberrations should lead not only to a deeper understanding of the specific cause of fibroids, but also to the discovery of new therapeutic targets. Targeting the products of genetic mutations or fibroid stem cells has the potential to achieve both better control of current tumors and the prevention of new fibroids.

Vitamin D3 Inhibits Wnt/β-Catenin and mTOR Signaling Pathways in Human Uterine Fibroid Cells

CONTEXT

Somatic mutations in the Med12 gene are known to activate Wnt/β-catenin signaling in human uterine fibroids (UFs).

OBJECTIVE

The objective of the study was to examine the role of vitamin D3 in the modulation of Wnt/β-catenin and mammalian target of rapamycin (mTOR) signaling in human UF cells.

DESIGN

Immortalized human UF cells (HuLM) and human primary UF (PUF) cells were treated with increasing concentrations of vitamin D3 and thereafter analyzed using Western blots and immunocytochemistry.

MAIN OUTCOME MEASURES

Wnt/β-catenin and mTOR signaling proteins in cultured HuLM and PUF cells were measured.

RESULTS

UF tumors with Med12 somatic mutations showed an up-regulation of Wnt4 and β-catenin as compared with adjacent myometrium. Vitamin D3 administration reduced the levels of Wnt4 and β-catenin in both HuLM and PUF cells. Vitamin D3 also reduced the expression/activation of mTOR signaling in both cell types. In contrast, vitamin D3 induced the expression of DNA damaged-induced transcription 4 (an inhibitor of mTOR) and tuberous sclerosis genes (TSC1/2) in a concentration-dependent manner in HuLM cells. Furthermore, we observed a concentration-dependent reduction of Wisp1 (Wnt induced signaling protein 1) and flap endonuclease 1 proteins in HuLM cells. Additionally, abrogation of vitamin D receptor expression (by silencing) in normal myometrial cells induces Wnt4/β-catenin as well as prompts a fibrotic process including an increase in cell proliferation and increased extracellular matrix production. Together these results suggest that vitamin D3 functions as an inhibitor of Wnt4/β-catenin and mTOR signaling pathways, which may play major roles in fibroid pathogenesis.

CONCLUSIONS

Vitamin D3 may have utility as a novel long-term therapeutic and/or preventive option for uterine fibroids.

Identification of Polycomb Group Protein EZH2-Mediated DNA Mismatch Repair Gene MSH2 in Human Uterine Fibroids

Uterine fibroids (UFs) are benign smooth muscle neoplasms affecting up to 70% of reproductive age women. Treatment of symptomatic UFs places a significant economic burden on the US health-care system. Several specific genetic abnormalities have been described as etiologic factors of UFs, suggesting that a low DNA damage repair capacity may be involved in the formation of UF. In this study, we used human fibroid and adjacent myometrial tissues, as well as an in vitro cell culture model, to evaluate the expression of MutS homolog 2 (MSH2), which encodes a protein belongs to the mismatch repair system. In addition, we deciphered the mechanism by which polycomb repressive complex 2 protein, EZH2, deregulates MSH2 in UFs. The RNA expression analysis demonstrated the deregulation of MSH2 expression in UF tissues in comparison to its adjacent myometrium. Notably, protein levels of MSH2 were upregulated in 90% of fibroid tissues (9 of 10) as compared to matched adjacent myometrial tissues. Human fibroid primary cells treated with 3-deazaneplanocin A (DZNep), chemical inhibitor of EZH2, exhibited a significant increase in MSH2 expression (P < .05). Overexpression of EZH2 using an adenoviral vector approach significantly downregulated the expression of MSH2 (P < .05). Chromatin immunoprecipitation assay demonstrated that enrichment of H3K27me3 in promoter regions of MSH2 was significantly decreased in DZNep-treated fibroid cells as compared to vehicle control. These data suggest that EZH2-H3K27me3 regulatory mechanism dynamically changes the expression levels of DNA mismatch repair gene MSH2, through epigenetic mark H3K27me3. MSH2 may be considered as a marker for early detection of UFs.

The Polycomb Group Protein EZH2 Impairs DNA Damage Repair Gene Expression in Human Uterine Fibroids

Uterine fibroids are benign, smooth muscle tumors that occur in approximately 70%-80% of women by age 50 yr. The cellular and molecular mechanism(s) by which uterine fibroids (UFs) develop are not fully understood. Accumulating evidence demonstrates that several genetic abnormalities, including deletions, rearrangements, translocations, as well as mutations, have been found in UFs. These genetic anomalies suggest that low DNA damage repair capacity may be involved in UF formation. The objective of this study was to determine whether expression levels of DNA damage repair-related genes were altered, and how they were regulated in the pathogenesis of UFs. Expression levels of DNA repair-related genes RAD51 and BRCA1 were deregulated in fibroid tissues as compared to adjacent myometrial tissues. Expression levels of chromatin protein enhancer of zeste homolog 2 (EZH2) were higher in a subset of fibroids as compared to adjacent myometrial tissues by both immunohistochemistry and Western blot analysis. Treatment with an inhibitor of EZH2 markedly increased expression levels of RAD51 and BRCA1 in fibroid cells and inhibited cell proliferation paired with cell cycle arrest. Restoring the expression of RAD51 and BRCA1 by treatment with EZH2 inhibitor was dependent on reducing the enrichment of trimethylation of histone 3 lysine 27 epigenetic mark in their promoter regions. This study reveals the important role of EZH2-regulated DNA damage-repair genes via histone methylation in fibroid biology, and may provide novel therapeutic targets for the medical treatment of women with symptomatic UFs.