Analysis of androgen receptor DNA reveals the independent clonal origins of uterine leiomyomata and the secondary nature of cytogenetic aberrations in the development of leiomyomata

Bipedalism and the dawn of uterine fibroids

The high prevalence and burden of uterine fibroids in women raises questions about the origin of these benign growths. Here, we propose that fibroids should be understood in the context of human evolution, specifically the advent of bipedal locomotion in the hominin lineage. Over the ≥7 million years since our arboreal ancestors left their trees, skeletal adaptations ensued, affecting the pelvis, limbs, hands, and feet. By 3.2 million years ago, our ancestors were fully bipedal. A key evolutionary advantage of bipedalism was the freedom to use hands to carry and prepare food and create and use tools which, in turn, led to further evolutionary changes such as brain enlargement (encephalization), including a dramatic increase in the size of the neocortex. Pelvic realignment resulted in narrowing and transformation of the birth canal from a simple cylinder to a convoluted structure with misaligned pelvic inlet, mid-pelvis, and pelvic outlet planes. Neonatal head circumference has increased, greatly complicating parturition in early and modern humans, up to and including our own species. To overcome the so-called obstetric dilemma provoked by bipedal locomotion and encephalization, various compensatory adaptations have occurred affecting human neonatal development. These include adaptations limiting neonatal size, namely altricial birth (delivery of infants at an early neurodevelopmental stage, relative to other primates) and mid-gestation skeletal growth deceleration. Another key adaptation was hyperplasia of the myometrium, specifically the neomyometrium (the outer two-thirds of the myometrium, corresponding to 90% of the uterine musculature), allowing the uterus to more forcefully push the baby through the pelvis during a lengthy parturition. We propose that this hyperplasia of smooth muscle tissue set the stage for highly prevalent uterine fibroids. These fibroids are therefore a consequence of the obstetric dilemma and, ultimately, of the evolution of bipedalism in our hominin ancestors.

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.

Single-cell sequencing reveals novel cellular heterogeneity in uterine leiomyomas

STUDY QUESTION

What are the cellular composition and single-cell transcriptomic differences between myometrium and leiomyomas as defined by single-cell RNA sequencing?

SUMMARY ANSWER

We discovered cellular heterogeneity in smooth muscle cells (SMCs), fibroblast and endothelial cell populations in both myometrium and leiomyoma tissues.

WHAT IS KNOWN ALREADY

Previous studies have shown the presence of SMCs, fibroblasts, endothelial cells and immune cells in myometrium and leiomyomas. However, there is no information on the cellular heterogeneity in these tissues and the transcriptomic differences at the single-cell level between these tissues.

STUDY DESIGN, SIZE, DURATION

We collected five leiomyoma and five myometrium samples from a total of eight patients undergoing hysterectomy. We then performed single-cell RNA sequencing to generate a cell atlas for both tissues. We utilized our single-cell sequencing data to define cell types, compare cell types by tissue type (leiomyoma versus myometrium) and determine the transcriptional changes at a single-cell resolution between leiomyomas and myometrium. Additionally, we performed MED12-variant analysis at the single-cell level to determine the genotype heterogeneity within leiomyomas.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We collected five MED12-variant positive leiomyomas and five myometrium samples from a total of eight patients. We then performed single-cell RNA sequencing on freshly isolated single-cell preparations. Histopathological assessment confirmed the identity of the samples. Sanger sequencing was performed to confirm the presence of the MED12 variant in leiomyomas.

MAIN RESULTS AND ROLE OF CHANCE

Our data revealed previously unknown heterogeneity in the SMC, fibroblast cell and endothelial cell populations of myometrium and leiomyomas. We discovered the presence of two different lymphatic endothelial cell populations specific to uterine leiomyomas. We showed that both myometrium and MED12-variant leiomyomas are relatively similar in cellular composition but differ in cellular transcriptomic profiles. We found that fibroblasts influence the leiomyoma microenvironment through their interactions with endothelial cells, immune cells and SMCs. Variant analysis at the single-cell level revealed the presence of both MED12 variants as well as the wild-type MED12 allele in SMCs of leiomyomatous tissue. These results indicate genotype heterogeneity of cellular composition within leiomyomas.

LARGE SCALE DATA

The datasets are available in the NCBI Gene Expression Omnibus (GEO) using GSE162122.

LIMITATIONS, REASONS FOR CAUTION

Our study focused on MED12-variant positive leiomyomas for single-cell RNA sequencing analyses. Leiomyomas carrying other genetic rearrangements may differ in their cellular composition and transcriptomic profiles.

WIDER IMPLICATIONS FOR THE FINDINGS

Our study provides a cellular atlas for myometrium and MED12-variant positive leiomyomas as defined by single-cell RNA sequencing. Our analysis provides significant insight into the differences between myometrium and leiomyomas at the single-cell level and reveals hitherto unknown genetic heterogeneity in multiple cell types within human leiomyomas. Our results will be important for future studies into the origin and growth of human leiomyomas.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by funding from the National Institute of Child Health and Human Development (HD098580 and HD088629). The authors declare no competing interests.

Cytogenomic Profile of Uterine Leiomyoma: In Vivo vs. In Vitro Comparison

We performed a comparative cytogenomic analysis of cultured and uncultured uterine leiomyoma (UL) samples. The experimental approach included karyotyping, aCGH, verification of the detected chromosomal abnormalities by metaphase and interphase FISH, MED12 mutation analysis and telomere measurement by Q-FISH. An abnormal karyotype was detected in 12 out of 32 cultured UL samples. In five karyotypically abnormal ULs, MED12 mutations were found. The chromosomal abnormalities in ULs were present mostly by complex rearrangements, including chromothripsis. In both karyotypically normal and abnormal ULs, telomeres were ~40% shorter than in the corresponding myometrium, being possibly prerequisite to chromosomal rearrangements. The uncultured samples of six karyotypically abnormal ULs were checked for the detected chromosomal abnormalities through interphase FISH with individually designed DNA probe sets. All chromosomal abnormalities detected in cultured ULs were found in corresponding uncultured samples. In all tumors, clonal spectra were present by the karyotypically abnormal cell clone/clones which coexisted with karyotypically normal ones, suggesting that chromosomal abnormalities acted as drivers, rather than triggers, of the neoplastic process. In vitro propagation did not cause any changes in the spectrum of the cell clones, but altered their ratio compared to uncultured sample. The alterations were unique for every UL. Compared to its uncultured counterpart, the frequency of chromosomally abnormal cells in the cultured sample was higher in some ULs and lower in others. To summarize, ULs are characterized by both inter- and intratumor genetic heterogeneity. Regardless of its MED12 status, a tumor may be comprised of clones with and without chromosomal abnormalities. In contrast to the clonal spectrum, which is unique and constant for each UL, the clonal frequency demonstrates up or down shifts under in vitro conditions, most probably determined by the unequal ability of cells with different genetic aberrations to exist outside the body.

Uterine Leiomyomas with an Apparently Normal Karyotype Comprise Minor Heteroploid Subpopulations Differently Represented in vivo and in vitro

In the present study, we aimed to check whether uterine leiomyomas (ULs) with an apparently normal karyotype in vitro comprise "hidden" cell subpopulations with numerical chromosome abnormalities (heteroploid cells). A total of 32 ULs obtained from 32 patients were analyzed in the study. Each UL was sampled for in vivo and in vitro cytogenetic studies. Karyotyping was performed on metaphase preparations from the cultured UL samples. A normal karyotype was revealed in 20 out of the 32 ULs, of which 9 were selected for further study based on the good quality of the interphase preparations. Then, using interphase FISH with centromeric DNA probes, we analyzed the copy number of chromosomes 7 and 16 in 1,000 uncultured and 1,000 cultured cells of each selected UL. All of the ULs included both disomic cells representing a predominant subpopulation and heteroploid cells reaching a maximum frequency of 21.6% (mean 9.8%) in vivo and 11.5% (mean 6.1%) in vitro. The spectrum of heteroploid cells was similar in vivo and in vitro and mostly consisted of monosomic and tetrasomic cells. However, their frequencies in the cultured samples differed from those in the uncultured ones: while the monosomic cells decreased in number, the tetrasomic cells became more numerous. The frequency of either monosomic or tetrasomic cells both in vivo and in vitro was not associated with the presence of MED12 exon 2 mutations in the tumors. Our results suggest that ULs with an apparently normal karyotype consist of both karyotypically normal and heteroploid cells, implying that the occurrence of minor cell subpopulations with numerical chromosome abnormalities may be considered a characteristic of UL tumorigenesis. Different frequencies of heteroploid cells in vivo and in vitro suggest their dependence on microenvironmental conditions, thus providing a pathway for regulation of their propagation, which may be important for the UL pathogenesis.

Selective Progesterone Receptor Modulators-Mechanisms and Therapeutic Utility

Selective progesterone receptor modulators (SPRMs) are a new class of compounds developed to target the progesterone receptor (PR) with a mix of agonist and antagonist properties. These compounds have been introduced for the treatment of several gynecological conditions based on the critical role of progesterone in reproduction and reproductive tissues. In patients with uterine fibroids, mifepristone and ulipristal acetate have consistently demonstrated efficacy, and vilaprisan is currently under investigation, while studies of asoprisnil and telapristone were halted for safety concerns. Mifepristone demonstrated utility for the management of endometriosis, while data are limited regarding the efficacy of asoprisnil, ulipristal acetate, telapristone, and vilaprisan for this condition. Currently, none of the SPRMs have shown therapeutic success in treating endometrial cancer. Multiple SPRMs have been assessed for efficacy in treating PR-positive recurrent breast cancer, with in vivo studies suggesting a benefit of mifepristone, and multiple in vitro models suggesting the efficacy of ulipristal acetate and telapristone. Mifepristone, ulipristal acetate, vilaprisan, and asoprisnil effectively treated heavy menstrual bleeding (HBM) in patients with uterine fibroids, but limited data exist regarding the efficacy of SPRMs for HMB outside this context. A notable class effect of SPRMs are benign, PR modulator-associated endometrial changes (PAECs) due to the actions of the compounds on the endometrium. Both mifepristone and ulipristal acetate are effective for emergency contraception, and mifepristone was approved by the US Food and Drug Administration (FDA) in 2012 for the treatment of Cushing's syndrome due to its additional antiglucocorticoid effect. Based on current evidence, SPRMs show considerable promise for treatment of several gynecologic conditions.

Role of DNA damage and repair mechanisms in uterine fibroid/leiomyomas: a review

There has been a significant annual increase in the number of cases of uterine leiomyomas or fibroids (UF) among women of all races and ages across the world. A fortune is usually spent by the healthcare sector for fibroid-related treatments and management. Molecular studies have established the higher mutational heterogeneity in UF as compared to normal myometrial cells. The contribution of DNA damage and defects in repair responses further increases the mutational burden on the cells. This in turn leads to genetic instability, associated with cancer risk and other adverse reproductive health outcomes. Such and many more growing bodies of literature have highlighted the genetic/molecular, biochemical and clinical aspects of UF; none the less there appear to be a lacuna bridging the bench to bed gap in addressing and preventing this disease. Presented here is an exhaustive review of not only the molecular mechanisms underlying the predisposition to the disease but also possible strategies to effectively diagnose, prevent, manage, and treat this disease.

The effects of menopausal uterine fibroids on the prognosis of endometrium cancer

Objective:

This study aimed to evaluate any potential associations between uterine leiomyomas and endometrial cancer.

Materials and Methods:

This is a retrospective study of 153 female patients who have been operated because of endometrial carcinoma in our hospital between 2012 and 2017. Data were collected from hospital records. Study participants were divided into two groups according to the presence and absence of leiomyomas. These two groups were compared in terms of histopathological adenocarcinoma type, nuclear and histological grades, disease stage, para-aortic lymph node involvement, and myometrial invasion. For data analysis, Statistical Package for Social Sciences 15.0 software package was used. Comparison between the two groups was made using the chi-square test, and each variable was tested with the Student’s t-test for statistical significance.

Results:

No statistically significant differences were found between the groups with respect to age, tumor type, myometrial invasion, nuclear grade, or histological grade (p>0.05 for all). A significant difference was found between leiomyomas presence and lymph node metastases. The lymph node metastases were more common in patients without uterine leiomyomas (20.55%) than in those with them (5%; p=0.004). Analysis using the Federation of Obstetrics and Gynecology stages for the presence of leiomyomas indicated that the mean stages were 1A and 1B in patients with and without uterine leiomyomas, respectively (p=0.002).

Conclusion:

Uterine leiomyomas did not adversely affect the prognosis of patients with endometrial carcinoma. Moreover, lymph node involvement was less common, and stages were lower in patients with leiomyomas.

An HMGA2-p62-ERα axis regulates uterine leiomyomas proliferation

Uterine leiomyomas (ULM) are a major public health issue contributing to high morbidity and poor pregnancy outcomes. However, its molecular pathogenesis is poorly understood. HMGA2-ULM is the second major subtype of human ULM and associates with large sizes, fast-growth, and high percentages of estrogen receptor α (ERα). As altered ERα expression plays a distinct role in ULM growth, here, we investigate a regulatory mechanism driving ULM growth via HMGA2 and ERα. We reveal a positive correlation of HMGA2 with ERα protein and demonstrate that HMGA2 promotes ULM cells proliferation via ERα. In addition, autophagy pathway and p62/SQSTM1 (a selective autophagy receptor) are found to participate in the regulation of HMGA2 and ERα. Moreover, HMGA2 suppresses the transcription of p62 by binding to its promoter, meanwhile, p62 interacts with ERα, and inhibition of p62 increases ERα expression and enhances cell viability in ULM, suggesting a novel mechanism of the HMGA2-p62-ERα axis in ULM proliferation. Notably, rapamycin, a familiar autophagy agonist, reduces ERα levels and the proliferation ability of ULM cells. This study demonstrates a causal role of the HMGA2-p62-ERα axis in preventing autophagy and increasing ERα expression in HMGA2-ULM. Therefore, blocking HMGA2-p62-ERα axis and targeting autophagy pathway establish a roadmap toward HMGA2-ULM medical treatment.

Reasons to Reconsider Risk Associated With Power Morcellation of Uterine Fibroids

Our insights into the molecular pathogenesis of uterine smooth muscle tumors have improved significantly. Accordingly, in the present review, we advocate a more refined risk assessment for patients considering surgical removal of fibroids or hysterectomy, respectively, requiring morcellation. For this procedure, the risk estimates given for the iatrogenic spread of a previously unexpected malignancy considerably vary among different studies. Nearly all previous studies conducted retrospectively refer to the risk of a patient having an unexpected malignancy at the time of surgery. We feel that, more appropriately, risk should refer to the number of tumors because, as a rule, every single nodule arises independently and, thus, carries an independent risk of being malignant or not. Furthermore, whether so-called parasitic fibroids carry an underestimated risk of stepwise malignant transformation is discussed.

A clinicopathological and molecular analysis in uterine leiomyomas and concurrent/metachronous peritoneal nodules: New insights into disseminated peritoneal leiomyomatosis

Disseminated peritoneal leiomyomatosis (DPL) is a rare, benign entity, but DPL following morcellation has become a major concern recently. This study aimed to investigate the molecular relationship between uterine leiomyoma and DPL. We analyzed the clinicopathological and molecular features of 8 DPL patients including 6 (#3-8) with and 2 (#1 and 2) without antecedent morcellation. Patients 1 and 2 were characterized by numerous, small peritoneal nodules whereas patients 4-8 harbored less but larger peritoneal nodules. Patient 3 had a peritoneal carcinomatosis-like dissemination, but she has been alive with disease for 68 months. Histological examination confirmed the diagnosis of leiomyomas in the uterus and extra-uterine sites. Immunohistochemistry demonstrated that both uterine and extra-uterine tumors were invariably positive for HMGA2 and MED12. MED12 mutation (c.130 G > A, p.G44S) was found in original uterine (n = 3) and peritoneal (n = 11) tumors from patients 3, 6, 7 and 8. Microsatellite instability at TPOX and D19S433 was observed in the uterine leiomyoma (patient 2) whereas LOH at CSF1PO was found in the peritoneal tumors (patient 1). D13S317 LOH was present in both uterine and peritoneal tumors detected (patient 8). However, D3S1358 LOH and D19S433 LOH was only found in the peritoneal tumors (patient 8) and recurrent tumors (patient 3), respectively. We suggested that DPLs following morcellation might be closely associated with original uterine leiomyomas. DPLs with and without prior morcellation may harbor different pathogenetic pathways. These findings are critical for the clinical intervention and prevention of DPL patients.

Factors targeting MED12 to drive tumorigenesis?

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 MED12-mutation positive tumors of independent clonal origin increases with the number of tumors per patient suggesting unknown etiological factors supporting site specific mutagenesis.  These factors may act by inducing simultaneous site-specific double strand breaks the erroneous repair of which may lead to corresponding mutations. As inducers of DNA damage and its repair such as foreign nucleic acids of the microbiome displaying sequence homology to the putative target site might play a role. Interestingly, a 16 base pair homology of the hotspot to a putative terminator base-paired hairpin sequence of a Staphylococcus aureus tRNA gene cluster has been noted which might form R-loop like structures with its target sequence thus inducing said changes.

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.

Epidemiology of Uterine Fibroids: From Menarche to Menopause

Uterine leiomyomata (UL) have a substantial impact on women's health, but relatively few studies have identified opportunities for primary prevention of these neoplasms. Most established risk factors are not modifiable, including premenopausal age, African ancestry, age at menarche, and childbearing history. The main challenge in studying UL is that a large proportion of tumors are asymptomatic. Herein, we review the epidemiology of UL from published studies to date. We highlight the advantages of ultrasound screening studies and the ways in which their innovative methods have helped clarify the etiology of disease. We conclude with a discussion of promising new hypotheses.

Influence of vitamin D and transforming growth factor β3 serum concentrations, obesity, and family history on the risk for uterine fibroids

OBJECTIVE

To evaluate the influence of 25-hydroxyvitamin D and transforming growth factor β3 (TGF-β3) serum concentrations, weight, and family history on the risk of developing uterine fibroids.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

PATIENT(S)

A total of 188 women, including patients admitted for uterine fibroid surgery (n = 105) as the study group and healthy women of similar age (n = 83) as controls.

INTERVENTION(S)

Medical history and completion of specially designed questionnaire, transvaginal or transabdominal genital ultrasound scan, blood sampling, and measurement of vitamin D and TGF-β3 serum concentrations.

MAIN OUTCOME MEASURE(S)

Evaluation of the impact of family history, vitamin D, and TGF-β3 serum concentrations on the risk of developing uterine fibroids.

RESULT(S)

Mean 25-hydroxyvitamin D serum concentrations were 21.9 ± 8.9 ng/mL and 26.7 ± 11.9 ng/mL in patients with uterine fibroids and controls, respectively. The difference was statistically significant. The TGF-β3 serum concentrations in the fibroid-positive group ranged from 1.20 to 436.15 pg/mL (half the patients had concentrations >16.25 pg/mL). Concentrations in the control group ranged from 0.96 to 49.08 pg/mL (half the women had concentrations of >11.80 pg/mL). The differences were statistically significant. Higher body mass index (BMI) and positive family history were also found to be among the risk factors for uterine fibroids.

CONCLUSION(S)

Our study confirmed higher BMI, positive family history, and lower vitamin D and higher TGF-β3 serum concentrations as risk factors for uterine fibroids.

Uterine fibroids and cardiovascular risk

STUDY QUESTION

Are uterine fibroids associated with increased cardiovascular risk?

SUMMARY ANSWER

This study reports an association between increased serum lipids and metabolic syndrome with an increased risk of uterine fibroids.

WHAT IS KNOWN ALREADY

Recent studies suggest similarities in biological disease mechanisms and risk factors for fibroids and atherosclerosis: obesity, hypertension and abnormal serum lipids. These findings are awaiting confirmation that a population-based follow-up study could offer with extensive health examination data collection linked with a national hospital discharge register.

STUDY DESIGN, SIZE, DURATION

The Northern Finland Birth Cohort (NFBC1966) is a population-based long-term follow-up study including all children with estimated date of delivery in 1966 in the Northern Finland area. The data were collected from national registries, postal questionnaires and clinical health examinations. The study population for this study comprised all females included in the NFBC1966 that underwent an extensive clinical health examination at age 46 years (n = 3635).

PARTICIPANTS/MATERIALS, SETTING, METHODS

All females included in the NFBC1966 who were alive and traceable (n = 5118) were invited for the 46-year follow-up study; 3268 (63.9%) responded, returned the postal questionnaire and attended the clinical examination. Uterine fibroid cases were identified through the national hospital discharge register that has data on disease diagnoses based on WHO ICD-codes. Uterine fibroid codes, ICD-9: 218 and ICD-10: D25 were used for case identification. Self-reported fibroid cases were identified through the postal questionnaire.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 729 fibroid cases were identified, including 293 based on hospital discharge registries. With adjustment for BMI, parity, education and current use of exogenous hormones the risk of prevalent fibroids rose significantly for every 1 mmol/l increase in LDL (OR = 1.13, 95% CI: 1.02-1.26 for all cases) and triglycerides (OR = 1.27, 95% CI: 1.09-1.49 for all cases). Metabolic syndrome associated with hospital discharge-based fibroid diagnosis (OR = 1.48, 95% CI: 1.09-2.01). Additionally every 1 unit increase in waist-hip ratio associated with fibroids (OR = 1.32, 95% CI: 1.10-1.57).

LIMITATIONS, REASONS FOR CAUTION

The case ascertainment may present some limitations. There was likely an under-identification of cases and misclassification of some cases as controls; this would have diluted the effects of reported associations. The data analysed were cross-sectional and therefore cause and effect for the associations observed cannot be distinguished.

WIDER IMPLICATIONS OF THE FINDINGS

Increased serum lipids and metabolic syndrome are associated with increased risk of uterine fibroids. Along with central obesity these findings add to an increased risk for cardiovascular disease among women with fibroids. These observations may suggest that there are shared predisposing factors underlying both uterine fibroids and adverse metabolic and cardiac disease risk, or that metabolic factors have a role in biological mechanisms underlying fibroid development.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the Academy of Finland, University Hospital Oulu, University of Oulu, Finland, Northern Finland Health Care Foundation, Duodecim Foundation, ERDF European Regional Development Fund-Well-being and health: Research in the Northern Finland Birth Cohort 1966. The authors declare no conflict of interest.

Exploring chromosomal abnormalities and genetic changes in uterine smooth muscle tumors

Smooth muscle tumors of the uterus are a diagnostically challenging group of tumors. Molecular surrogate markers reliably distinguishing between benign and malignant tumors are not available. Therefore, the diagnosis is based on morphologic criteria. The aim was to investigate a well-characterized group of challenging uterine smooth muscle tumors consisting of 20 leiomyomas, 13 leiomyomas with bizarre nuclei, and 14 leiomyosarcomas for copy number alterations, MED12 mutations and FH deletions to search for potential diagnostically useful surrogate markers. MED12 mutations were detected in 47, 15, and 25% of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas, respectively. MED12 mutations in leiomyomas with bizarre nuclei were detected outside the hotspot region. FH-deletions were seen in 27, 30.8, and 25% of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas, respectively. By using copy number alteration profiling a clear separation of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas could not be observed. Copy number alterations revealed clear genetic similarities between leiomyomas with bizarre nuclei and leiomyosarcomas. Leiomyosarcomas showed a similar pattern of gains and losses as leiomyomas with bizarre nuclei, with additional copy number alterations and more homozygous losses and high-level amplifications compared to leiomyomas with bizarre nuclei. In conclusion, this study demonstrates that known FH-deletions, a recurrent molecular change in leiomyomas, occur in morphologically challenging variants of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas. Although MED12 mutations are common in leiomyomas, they infrequently occur in leiomyomas with bizarre nuclei and leiomyosarcomas. The genetic similarities between leiomyomas with bizarre nuclei and leiomyosarcomas raise the intriguing possibility that uterine leiomyomas with bizarre nuclei and leiomyosarcomas are closely related and challenge the traditional concept that leiomyoma with bizarre nuclei is a tumor with just marked 'degenerative' cellular changes. These findings support the hypothesis that tumor progression within uterine smooth muscle tumors might occur.

Intravenous leiomyomatosis: an unusual intermediate between benign and malignant uterine smooth muscle tumors

Intravenous leiomyomatosis is an unusual smooth muscle neoplasm with quasi-malignant intravascular growth but a histologically banal appearance. Herein, we report expression and molecular cytogenetic analyses of a series of 12 intravenous leiomyomatosis cases to better understand the pathogenesis of intravenous leiomyomatosis. All cases were analyzed for the expression of HMGA2, MDM2, and CDK4 proteins by immunohistochemistry based on our previous finding of der(14)t(12;14)(q14.3;q24) in intravenous leiomyomatosis. Seven of 12 (58%) intravenous leiomyomatosis cases expressed HMGA2, and none expressed MDM2 or CDK4. Colocalization of hybridization signals for probes from the HMGA2 locus (12q14.3) and from 14q24 by interphase fluorescence in situ hybridization (FISH) was detected in a mean of 89.2% of nuclei in HMGA2-positive cases by immunohistochemistry, but in only 12.4% of nuclei in negative cases, indicating an association of HMGA2 expression and this chromosomal rearrangement (P=8.24 × 10(-10)). Four HMGA2-positive cases had greater than two HMGA2 hybridization signals per cell. No cases showed loss of a hybridization signal by interphase FISH for the frequently deleted region of 7q22 in uterine leiomyomata. One intravenous leiomyomatosis case analyzed by array comparative genomic hybridization revealed complex copy number variations. Finally, expression profiling was performed on three intravenous leiomyomatosis cases. Interestingly, hierarchical cluster analysis of the expression profiles revealed segregation of the intravenous leiomyomatosis cases with leiomyosarcoma rather than with myometrium, uterine leiomyoma of the usual histological type, or plexiform leiomyoma. These findings suggest that intravenous leiomyomatosis cases share some molecular cytogenetic characteristics with uterine leiomyoma, and expression profiles similar to that of leiomyosarcoma cases, further supporting their intermediate, quasi-malignant behavior.

Possible involvement of inflammatory/reparative processes in the development of uterine fibroids

Uterine leiomyomas are benign tumors in the smooth muscle layer of the uterus. The most common histological type is the "usual leiomyoma", characterized by overexpression of ECM proteins, whereas the "cellular type" has higher cellular content. Our objective is to investigate the involvement of inflammatory and reparative processes in leiomyoma pathobiology. Using a morphological approach, we investigate the presence of inflammatory cells. Next, we determine the localization of the ECM, the presence/absence of fibrotic cells via α-sma and desmin and the immunohistochemical profile of the mesenchymal cells with respect to CD34. Finally, we explore the effect of inflammatory mediators (TNF-α, IL-1β, IL-6, IL-15, GM-CSF and IFN-γ) on pro-fibrotic factor activin A mRNA expression in vitro. Higher numbers of macrophages were found inside and close to leiomyomas as compared to the more distant myometrium. Cellular leiomyomas showed more macrophages and mast cells than the "usual type". Inside the fibroid tissue, we found cells positive for α-sma, but negative for desmin and a large amount of collagen surrounding the nodule, suggestive of myofibroblasts producing ECM. In the myometrium and leiomyomas of the "usual type", we identified numerous CD34+ fibroblasts, which are known to give rise to myofibroblasts upon loss of CD34 expression. In leiomyomas of the "cellular type", stromal fibroblasts were CD34-negative. Finally, we found that TNF-α increased activin A mRNA in myometrial and leiomyoma cells. In conclusion, this study demonstrates the presence of inflammatory cells in uterine leiomyomas, which may contribute to excessive ECM production, tissue remodeling and leiomyoma growth.

Epidemiological and genetic clues for molecular mechanisms involved in uterine leiomyoma development and growth

BACKGROUND

Uterine leiomyomas (fibroids) are highly prevalent benign smooth muscle tumors of the uterus. In the USA, the lifetime risk for women developing uterine leiomyomas is estimated as up to 75%. Except for hysterectomy, most therapies or treatments often provide only partial or temporary relief and are not successful in every patient. There is a clear racial disparity in the disease; African-American women are estimated to be three times more likely to develop uterine leiomyomas and generally develop more severe symptoms. There is also familial clustering between first-degree relatives and twins, and multiple inherited syndromes in which fibroid development occurs. Leiomyomas have been described as clonal and hormonally regulated, but despite the healthcare burden imposed by the disease, the etiology of uterine leiomyomas remains largely unknown. The mechanisms involved in their growth are also essentially unknown, which has contributed to the slow progress in development of effective treatment options.

METHODS

A comprehensive PubMed search for and critical assessment of articles related to the epidemiological, biological and genetic clues for uterine leiomyoma development was performed. The individual functions of some of the best candidate genes are explained to provide more insight into their biological function and to interconnect and organize genes and pathways in one overarching figure that represents the current state of knowledge about uterine leiomyoma development and growth.

RESULTS

In this review, the widely recognized roles of estrogen and progesterone in uterine leiomyoma pathobiology on the basis of clinical and experimental data are presented. This is followed by fundamental aspects and concepts including the possible cellular origin of uterine fibroids. The central themes in the subsequent parts are cytogenetic aberrations in leiomyomas and the racial/ethnic disparities in uterine fibroid biology. Then, the attributes of various in vitro and in vivo, human syndrome, rodent xenograft, naturally mutant, and genetically modified models used to study possible molecular mechanisms of leiomyoma development and growth are described. Particular emphasis is placed on known links to fibrosis, hypertrophy, and hyperplasia and genes that are potentially important in these processes.

CONCLUSIONS

Menstrual cycle-related injury and repair and coinciding hormonal cycling appears to affect myometrial stem cells that, at a certain stage of fibroid development, often obtain cytogenetic aberrations and mutations of Mediator complex subunit 12 (MED12). Mammalian target of rapamycin (mTOR), a master regulator of proliferation, is activated in many of these tumors, possibly by mechanisms that are similar to some human fibrosis syndromes and/or by mutation of upstream tumor suppressor genes. Animal models of the disease support some of these dysregulated pathways in fibroid etiology or pathogenesis, but none are definitive. All of this suggests that there are likely several key mechanisms involved in the disease that, in addition to increasing the complexity of uterine fibroid pathobiology, offer possible approaches for patient-specific therapies. A final model that incorporates many of these reported mechanisms is presented with a discussion of their implications for leiomyoma clinical practice.

Clonally related uterine leiomyomas are common and display branched tumor evolution

Uterine leiomyomas are extremely frequent benign smooth muscle tumors often presenting as multiple concurrent lesions and causing symptoms such as abnormal menstrual bleeding, abdominal pain and infertility. While most leiomyomas are believed to arise independently, a few studies have encountered separate lesions harboring identical genetic changes, suggesting a common clonal origin. To investigate the frequency of clonally related leiomyomas, genome-wide tools need to be utilized, and thus little is known about this phenomenon. Using MED12 sequencing and SNP arrays, we searched for clonally related uterine leiomyomas in a set of 103 tumors from 14 consecutive patients who entered hysterectomy owing to symptomatic lesions. Whole-genome sequencing was also utilized to study the genomic architecture of clonally related tumors. This revealed four patients to have two or more tumors that were clonally related, all of which lacked MED12 mutations. Furthermore, some tumors were composed of genetically distinct subclones, indicating a nonlinear, branched model of tumor evolution. DEPDC5 was discovered as a novel tumor suppressor gene playing a role in the progression of uterine leiomyomas. Perhaps counterintuitively—considering Knudson's two-hit hypothesis—a large shared deletion was followed by different truncating DEPDC5 mutations in four clonally related leiomyomas. This study provides insight into the intratumor heterogeneity of these tumors and suggests that a shared clonal origin is a common feature of leiomyomas that do not carry an MED12 mutation. These observations also offer one explanation to the common occurrence of multiple concurrent lesions.

Contemporary management of uterine fibroids: focus on emerging medical treatments

OBJECTIVE

This review provides an overview of therapeutic options, with a specific focus on the emerging role of medical options for UF management.

RESEARCH DESIGN AND METHODS

PubMed, Google Scholar, and Cochrane Systematic Reviews were searched for articles published between 1980 and 2013. Relevant articles were identified using the following terms: 'uterine fibroids', 'leiomyoma', 'heavy menstrual bleeding', and 'menorrhagia'. The reference lists of articles identified were also searched for other relevant publications.

RESULTS

Because of the largely benign nature of UFs, the most conservative options that minimize morbidity/risk and optimize outcomes should be considered. Watchful waiting, or no immediate intervention combined with regular follow-up, is an appropriate option for the majority of UF patients who experience no symptoms. For women with symptomatic UFs, the optimal treatment should restore quality of life through rapid relief of UF signs and symptoms, reduce tumor size for a sustained period, and maintain or improve fertility. Invasive surgical treatments, such as hysterectomy, have historically been the mainstay of UF treatment. Less invasive surgical and interventional techniques, such as myomectomy, uterine artery embolization, endometrial ablation, and myolysis provide alternatives to hysterectomy. Until recently, medical management of UFs was characterized by short-term treatments and therapies that provided symptomatic control. In addition to controlling abnormal uterine bleeding, newer medical therapies, including the recently Health-Canada-approved ulipristal acetate, act directly to shrink the tumor. Although no agent is currently approved for such use, emerging evidence suggests the potential for long-term medical management of UFs.

CONCLUSIONS

The advent of novel medical therapies may diminish the long-held reliance on more invasive surgical UF treatment options.

Genomics of uterine leiomyomas: insights from high-throughput sequencing

Uterine leiomyomas are benign smooth-muscle tumors of extremely low malignant potential. Early work utilizing classical cytogenetics revealed that a subset of uterine leiomyomas harbor recurrent chromosomal rearrangements, such as translocations affecting the HMGA2 gene. Our understanding of the genetics of many tumor types has deepened remarkably with the emergence of next-generation sequencing technologies. Exome sequencing identified that the majority of leiomyomas display highly specific MED12 mutations. Further studies suggest that these MED12 hotspot mutations are also frequent in breast fibroadenomas, but not in other human tumors. Whole-genome sequencing showed that a subset of leiomyomas display complex chromosomal rearrangements resembling chromothripsis. These were formed in a single event of chromosomal breakage and random reassembly involving one or a limited number of chromosomes. Although most leiomyomas have been shown to arise independently, these studies also revealed that distinct nodules within a uterus may display identical genetic changes indicating a common clonal origin. A minority of leiomyomas were also found to display deletions within the COL4A5-COL4A6 genes, leading to upregulation of the adjacent gene IRS4. The findings derived from high-throughput sequencing combined with previous knowledge have led to an emerging molecular classification of leiomyomas, suggesting that there are several distinct pathogenic pathways involved in leiomyoma formation. The evidence points to at least 4 molecular subclasses: leiomyomas with MED12 mutation, FH inactivation, HMGA2 overexpression, and COL4A6-COL4A5 deletion. Elucidating the molecular pathogenesis of leiomyomas should be relevant for developing treatments for this very common disease.

The CD24hi smooth muscle subpopulation is the predominant fraction in uterine fibroids

Uterine fibroids are the most common gynecological tumors affecting women in their reproductive age. Despite this high incidence the pathogenesis of fibroids is widely unsolved. Whereas formerly only imbalances in hormonal levels were considered to account for tumor development, the identification of genetic changes likely to affect myometrial stem cell reservoirs provided a novel approach to fibroid genesis. Here, we identified a certain subset of cells by the surface marker CD24 with increased abundance in fibroids compared with myometrial tissue. Fibroid cells expressing CD24 shared certain features of immature or progenitor-like cells such as quiescence, reduced expression of smooth muscle differentiation markers and elevated expression of genes involved in the wingless-type (WNT)-pathway such as beta-catenin. In addition, a positive correlation between CD24 and wingless-type family member 4 (WNT4) expression was observed in uterine fibroids with mediator subcomplex 12 gene (MED12) mutations. Our findings suggest that cells highly expressing CD24 represent a type of immature smooth muscle progenitor cells. Their accumulation might be driven by disturbed differentiation processes caused by genetic changes possibly involving MED12 mutations or high mobility group AT-hook (HMGA)2 rearrangements.

Cell cultures in uterine leiomyomas: rapid disappearance of cells carrying MED12 mutations

Uterine leiomyomas (UL) are the most frequent symptomatic human tumors. Nevertheless, their molecular pathogenesis is not yet fully understood. To learn more about the biology of these common neoplasms and their response to treatment, cell cultures derived from UL are a frequently used model system, but until recently appropriate genetic markers confirming their origin from the tumor cell population were lacking for most UL, i.e., those not displaying karyotypic abnormalities. The identification of MED12 mutations in the majority of UL makes it possible to trace the tumor cell population during in vitro passaging in the absence of cytogenetic abnormalities. The present study is addressing the in vitro survival of cells carrying MED12 mutations and its association with karyotypic alterations. The results challenge numerous in vitro studies into the biology and behavior of leiomyomas. Cells of one genetic subtype of UL, i.e., those with rearrangements of the high mobility AT-hook 2 protein gene (HMGA2), seem to be able to proliferate in vitro for many passages whereas tumor cells from the much more frequent MED12-mutated lesions barely survive even the first passages. Apparently, for the most frequent type of human UL no good in vitro model seems to exist because cells do not survive culturing. On the other hand, this inability may point to an Achilles' heel of this type of UL.

Clonality of smooth muscle and fibroblast cell populations isolated from human fibroid and myometrial tissues

Uterine fibroids are conventionally defined as clonally derived benign tumours from the proliferation of a single smooth muscle cell (SMC). We have previously identified fibroblast-like cells in fibroids, the presence of which raises the question as to whether all cells within the fibroid have the same clonal origin. The first aim of this study was to develop a fluorescence-activated cell sorting (FACS)-based method to isolate different cell types from human myometrium and fibroid tissues. Secondly, we aimed to use X chromosome inactivation analysis to determine the clonality of cell subpopulations isolated from myometrial and fibroid tissues. Human myometrium and fibroid tissues were collected from women undergoing hysterectomy. Immunohistochemistry (IHC) and flow cytometry confirmed that in addition to SMCs, fibroblasts constitute a significant proportion of cells in human myometrium and fibroid tissues. FACS based on CD90 and ALDH1 reliably separated cells into three myometrial and four fibroid subpopulations: SMCs, vascular smooth muscle cells and two fibroblast subsets. Clonality was first determined by X chromosome inactivation using the classic DNA methylation-sensitive HUMARA assay. Data from this assay were highly variable, with only a quarter of samples meeting the definition of clonal fibroid and non-clonal myometrium. However, using an RNA-based X chromosome inactivation HUMARA assay, we were able to demonstrate clonality of all cellular constituents of most fibroids. Our results confirm that most fibroids are derived from a single cell, and for the first time demonstrates that these clonal cells differentiate into fibroblast and SMC subpopulation as the fibroid grows.

Is fibroid heterogeneity a significant issue for clinicians and researchers?

The clinical and scientific literature overwhelmingly deals with fibroids as a single entity or disease. This convenient assumption of homogeneity may be an important oversight given that substantial evidence exists for heterogeneity between fibroids at many levels. Failure to recognize and accommodate fibroid heterogeneity can have significant ramifications for both clinical treatment decisions and research protocol design. The aim of this article is to review the current knowledge of fibroid heterogeneity and to identify key areas where fibroid heterogeneity should be taken into consideration both clinically and when designing research protocols. Uterine leiomyomata display significant and well-documented heterogeneity in symptoms, diagnostic imaging appearance, pathology, genetic background and therapeutic requirements. Additional research is needed to better understand fibroid heterogeneity as it relates to pathogenesis, molecular targets for potential new therapies, patient symptoms and, ultimately, treatment. To this list should also be added heterogeneity of genetics, lifestyle and individual clinical characteristics of the fibroid. Increasingly, an understanding of uterine leiomyoma heterogeneity will be of importance for clinicians who see patients with this common and costly disease.

Expression of p53 and p21(WAF-1), apoptosis, and proliferation of smooth muscle cells in normal myometrium during the menstrual cycle: implication of DNA damage and repair for leiomyoma development

Uterine leiomyoma is the most common tumor in the female genital tract, although its pathogenesis remains unclear. Molecular analyses have demonstrated that each leiomyoma nodule is monoclonal and harbors various DNA abnormalities, suggesting that DNA damage in normal smooth muscle cells plays an important role in the pathogenesis of leiomyoma. The aim of this study is to evaluate precisely when and where DNA damage occurs in the myometrium. The localization of damaged, apoptotic, and proliferating cells was evaluated by immunohistochemical staining of p53, p21(WAF-1), TUNEL, and the cell proliferation marker, Ki-67, in normal myometrium during the menstrual cycle. p53-positive cells and p21(WAF-1)-positive cells were observed during the follicular phase, mostly in the submucosal layer of the myometrium. TUNEL-positive cells were sporadically identified in this layer during either the menstrual or follicular phase. In contrast, the number of Ki-67-positive cells was higher in the luteal phase. These results suggest that DNA damage, repair, and apoptosis occur cyclically in normal myometrium during the follicular phase. In addition, smooth muscle cells proliferate in the luteal phase, which may be a vulnerable period for DNA damage. Thus, these cyclic events during the menstrual cycle may contribute to a high incidence of leiomyoma development.

MED12 mutations occurring in benign and malignant mammalian smooth muscle tumors

Mutations of the mediator subcomplex 12 gene (MED12) recently have been described in a large group of uterine leiomyomas (UL) but only in a single malignant uterine smooth muscle tumor. To further address the occurrence of fibroid-type MED12 mutations in smooth muscle tumors, we have analyzed samples from 34 leiomyosarcomas (LMS), 21 UL, two extrauterine leiomyomas (EL), and 10 canine genital leiomyomas for the presence of MED12 mutations of the UL-type. Interestingly, besides UL MED12 mutations were found in one uterine LMS, one EL, and two canine vaginal leiomyomas. The results confirm the occurrence of fibroid-type MED12 mutations in malignant uterine smooth muscle tumors thus suggesting a rare but existing leiomyoma-LMS sequence. In addition, for the first time MED12 mutations are reported in smooth muscle tumors in a non-primate mammalian species.

Identification of CUX1 as the recurrent chromosomal band 7q22 target gene in human uterine leiomyoma

Uterine leiomyomas are benign solid tumors of mesenchymal origin which occur with an estimated incidence of up to 77% of all women of reproductive age. The majority of these tumors remains symptomless, but in about a quarter of cases they cause leiomyoma-associated symptoms including chronic pelvic pain, menorrhagia-induced anemia, and impaired fertility. As a consequence, they are the most common indication for pre-menopausal hysterectomy in the USA and Japan and annually translate into a multibillion dollar healthcare problem. Approximately 40% of these neoplasms present with recurring structural cytogenetic anomalies, including del(7)(q22), t(12;14)(q15;q24), t(1;2)(p36;p24), and anomalies affecting 6p21 and/or 10q22. Using positional cloning strategies, we and others previously identified HMGA1, HMGA2, RAD51L1, MORF, and, more recently, NCOA1 as primary target (fusion) genes associated with tumor initiation in four of these distinct cytogenetic subgroups. Despite the fact that the del(7)(q22) subgroup is the largest among leiomyomas, and was first described more than twenty years ago, the 7q22 leiomyoma target gene still awaits unequivocal identification. We here describe a positional cloning effort from two independent uterine leiomyomas, containing respectively a pericentric and a paracentric chromosomal inversion, both affecting band 7q22. We found that both chromosomal inversions target the cut-like homeobox 1 (CUX1) gene on chromosomal band 7q22.1 in a way which is functionally equivalent to the more frequently observed del(7q) cases, and which is compatible with a mono-allelic knock-out scenario, similar as was previously described for the cytogenetic subgroup showing chromosome 14q involvement.

Evaluation of cardiovascular risk factors in women with uterine leimyoma: is there a link with atherosclerosis?

OBJECTIVE

Both uterine leimyoma (UL) and cardiovascular disease are public health problems affecting women at different age ranges. Smoking, obesity, and hypertension have been shown to be associated with UL in different random studies. However cardiovascular risk factors have not been evaluated systematically in patients with UL. Accordingly, we aimed to evaluate the cardiovascular risk factors and their relation with the presence of UL.

MATERIAL AND METHODS

One hundred and eighty nine patients with the pathological diagnosis of UL and one hundred and eighty nine age matched control subjects without UL were retrospectively included in the study from our data base of the pathology and gynecology departments. Controls were patients with intact uteri who had visited the same physicians for a routine checkup that included a pelvic examination and uterine sonogram and without mention of physical findings consistent with UL. The following clinical and demographic parameters were recorded; age, sex, hypertension, diabetes mellitus, and hypercholesterolemia. Current cigarette smoking was defined as active smoking within the past 12 months.

RESULTS

Comparison of cardiovascular risk factors between with and without UL revealed that the presence of hypertension (80 (42.3%) vs 53 (28%) p=0.004) diabetes mellitus (33 (17.4%) vs. 16 (8.4%) p=0.009), smoking (31 (16.4%) vs. 11 (5.8%) p=0.001), were significantly higher in patients with UL than in control subjects. The mean-age and presence of hyperlipidemia were comparable between the two groups. Logistic regression analysis revealed an independent and positive association of UL with the presence of hypertension (odds ratio 2.02 CI: 1.25-3.27 p=0.004), diabetes mellitus (odds ratio 2.43 CI: 1.23-4.79 p=0.010), and smoking status (odds ratio 3.46 CI: 1.65-7.22 p=0.001).

CONCLUSION

We have shown that major cardiovascular risk factors namely, hypertension, diabetes mellitus and smoking are significantly and independently associated with UL. Our findings highlight the possible association of UL with atherosclerosis.

MED12 alterations in both human benign and malignant uterine soft tissue tumors

The relationship between benign uterine leiomyomas and their malignant counterparts, i.e. leiomyosarcomas and smooth muscle tumors of uncertain malignant potential (STUMP), is still poorly understood. The idea that a leiomyosarcoma could derive from a leiomyoma is still controversial. Recently MED12 mutations have been reported in uterine leiomyomas. In this study we asked whether such mutations could also be involved in leiomyosarcomas and STUMP oncogenesis. For this purpose we examined 33 uterine mesenchymal tumors by sequencing the hot-spot mutation region of MED12. We determined that MED12 is altered in 66.6% of typical leiomyomas as previously reported but also in 11% of STUMP and 20% of leiomyosarcomas. The mutated allele is predominantly expressed in leiomyomas and STUMP. Interestingly all classical leiomyomas exhibit MED12 protein expression while 40% of atypical leiomyomas, 50% of STUMP and 80% of leiomyosarcomas (among them the two mutated ones) do not express MED12. All these tumors without protein expression exhibit complex genomic profiles. No mutations and no expression loss were identified in an additional series of 38 non-uterine leiomyosarcomas. MED12 mutations are not exclusive to leiomyomas but seem to be specific to uterine malignancies. A previous study has suggested that MED12 mutations in leiomyomas could lead to Wnt/β-catenin pathway activation however our immunohistochemistry results show that there is no association between MED12 status and β-catenin nuclear/cytoplasmic localization. Collectively, our results show that subgroups of benign and malignant tumors share a common genetics. We propose here that MED12 alterations could be implicated in the development of smooth muscle tumor and that its expression could be inhibited in malignant tumors.

Expression profiling of uterine leiomyomata cytogenetic subgroups reveals distinct signatures in matched myometrium: transcriptional profilingof the t(12;14) and evidence in support of predisposing genetic heterogeneity

Uterine leiomyomata (UL), the most common neoplasm in reproductive-age women, are classified into distinct genetic subgroups based on recurrent chromosome abnormalities. To develop a molecular signature of UL with t(12;14)(q14-q15;q23-q24), we took advantage of the multiple UL arising as independent clonal lesions within a single uterus. We compared genome-wide expression levels of t(12;14) UL to non-t(12;14) UL from each of nine women in a paired analysis, with each sample weighted for the percentage of t(12;14) cells to adjust for mosaicism with normal cells. This resulted in a transcriptional profile that confirmed HMGA2, known to be overexpressed in t(12;14) UL, as the most significantly altered gene. Pathway analysis of the differentially expressed genes showed significant association with cell proliferation, particularly G1/S checkpoint regulation. This is consistent with the known larger size of t(12;14) UL relative to karyotypically normal UL or to UL in the deletion 7q22 subgroup. Unsupervised hierarchical clustering demonstrated that patient variability is relatively dominant to the distinction of t(12;14) UL compared with non-t(12;14) UL or of t(12;14) UL compared with del(7q) UL. The paired design we employed is therefore important to produce an accurate t(12;14) UL-specific gene list by removing the confounding effects of genotype and environment. Interestingly, myometrium not only clustered away from the tumors, but generally separated based on associated t(12;14) versus del(7q) status. Nine genes were identified whose expression can distinguish the myometrium origin. This suggests an underlying constitutional genetic predisposition to these somatic changes which could potentially lead to improved personalized management and treatment.

MED12 mutations in uterine fibroids--their relationship to cytogenetic subgroups

Recurrent chromosomal alterations are found in roughly 20% of all uterine fibroids but in the majority cytogenetic changes are lacking. Recently, mutations of the gene mediator subcomplex 12 (MED12) have been detected in a majority of fibroids but no information is available whether or not they co-occur with cytogenetic subtypes as, e.g., rearrangements of the genes encoding high mobility group AT-hook (HMGA) proteins. In a total of 80 cytogenetically characterized fibroids from 50 patients, we were not only able to confirm the frequent occurrence of MED12 mutations but also to stratify two mutually exclusive pathways of leiomyomagenesis with either rearrangements of HMGA2 reflected by clonal chromosome abnormalities affecting 12q14~15 or by mutations affecting exon 2 of MED12. On average the latter mutations were associated with a significantly smaller tumor size. However, G>A transitions of nucleotides c.130 or c.131 correlate with a significantly larger size of the fibroids compared to other MED12 mutations thus explaining the high prevalence of the former mutations among clinically detectable fibroids. Interestingly, fibroids with MED12 mutations expressed significantly higher levels of the gene encoding wingless-type MMTV integration site family, member 4 (WNT4). Based on these findings and data from the literature, we hypothesize that estrogen and the mutated MED12 cooperate in activating the Wnt pathway which in turn activates β-catenin known to cause leiomyoma-like lesions in a mouse model. The occurrence of a "fibroid-type mutation" in a rare histologic subtype of endometrial polyps suggests that this mechanism is not confined to uterine leiomyomas.

Disseminated peritoneal leiomyomatosis after laparoscopic supracervical hysterectomy with characteristic molecular cytogenetic findings of uterine leiomyoma

Disseminated peritoneal leiomyomatosis (DPL) is a rare condition characterized by scattered smooth muscle nodules over the peritoneal surfaces. The pathogenesis of DPL remains unclear. Herein, we report a case of DPL occurring 7 years after laparoscopic supracervical hysterectomy with morcellation for uterine leiomyomata (UL). We analyzed both the original UL and the subsequent DPL by molecular cytogenetics to assess the role of chromosomal abnormalities in DPL pathobiology. Interestingly, all of the chromosomal aberrations detected in this case of DPL, including r(1)(p34.3q41), del(3)(q23q26.33), and t(12;14)(q14.3;q24.1), are characteristic chromosomal abnormalities detected in UL. Fluorescence in situ hybridization analysis of the initial UL confirmed an interstitial deletion spanning at least 3q24 and 3q25.1, suggesting that functional alteration of a potential gene in this chromosomal region may play a role in DPL development from UL. With the increasing rate of hysterectomy through laparoscopic approach to UL, the unique complications of laparoscopy with morcellation, especially seeding and proliferation of tumor cells over abdominal organs and peritoneum, are becoming more significant and may necessitate review of current surgical protocols to prevent future seeding of the pelvic region with tumor particles.

The expression of selenium-binding protein 1 is decreased in uterine leiomyoma

Background

Selenium has been shown to inhibit cancer development and growth through the mediation of selenium-binding proteins. Decreased expression of selenium-binding protein 1 has been reported in cancers of the prostate, stomach, colon, and lungs. No information, however, is available concerning the roles of selenium-binding protein 1 in uterine leiomyoma.

Methods

Using Western Blot analysis and immunohistochemistry, we examined the expression of selenium-binding protein 1 in uterine leiomyoma and normal myometrium in 20 patients who had undergone hysterectomy for uterine leiomyoma.

Results and Discussion

The patient age ranged from 34 to 58 years with a mean of 44.3 years. Proliferative endometrium was seen in 8 patients, secretory endometrium in 7 patients, and atrophic endometrium in 5 patients. Two patients showed solitary leiomyoma, and eighteen patients revealed 2 to 5 tumors. Tumor size ranged from 1 to 15.5 cm with a mean of 4.3 cm. Both Western Blot analysis and immunohistochemistry showed a significant lower level of selenium-binding protein 1 in leiomyoma than in normal myometrium. Larger tumors had a tendency to show a lower level of selenium-binding protein 1 than smaller ones, but the difference did not reach a statistical significance. The expression of selenium-binding protein 1 was the same among patients with proliferative, secretory, and atrophic endometrium in either leiomyoma or normal myometrium. Also, we did not find a difference of selenium-binding protein 1 level between patients younger than 45 years and older patients in either leiomyoma or normal myometrium.

Conclusions

Decreased expression of selenium-binding protein 1 in uterine leiomyoma may indicate a role of the protein in tumorigenesis. Our findings may provide a basis for future studies concerning the molecular mechanisms of selenium-binding protein 1 in tumorigenesis as well as the possible use of selenium in prevention and treatment of uterine leiomyoma.

Identifying the molecular signature of the interstitial deletion 7q subgroup of uterine leiomyomata using a paired analysis

Uterine leiomyomata (UL), the most common neoplasm in reproductive-age women, have recurrent cytogenetic abnormalities including interstitial deletion of 7q. To develop a molecular signature, matched del(7q) and non-del(7q) tumors identified by FISH or karyotyping from 11 women were profiled with expression arrays. Our analysis using paired t tests demonstrates this matched design is critical to eliminate the confounding effects of genotype and environment that underlie patient variation. A gene list ordered by genome-wide significance showed enrichment for the 7q22 target region. Modification of the gene list by weighting each sample for percent of del(7q) cells to account for the mosaic nature of these tumors further enhanced the frequency of 7q22 genes. Pathway analysis revealed two of the 19 significant functional networks were associated with development and the most represented pathway was protein ubiquitination, which can influence tumor development by stabilizing oncoproteins and destabilizing tumor suppressor proteins. Array CGH (aCGH) studies determined the only consistent genomic imbalance was deletion of 9.5 megabases from 7q22-7q31.1. Combining the aCGH data with the del(7q) UL mosaicism-weighted expression analysis resulted in a list of genes that are commonly deleted and whose copy number is correlated with significantly decreased expression. These genes include the proliferation inhibitor HPB1, the loss of expression of which has been associated with invasive breast cancer, as well as the mitosis integrity-maintenance tumor suppressor RINT1. This study provides a molecular signature of the del(7q) UL subgroup and will serve as a platform for future studies of tumor pathogenesis.

Overexpression of HMGA2 in uterine leiomyomas points to its general role for the pathogenesis of the disease

An overexpression of HMGA2 is supposed to be a key event in the genesis of leiomyoma with chromosomal rearrangements affecting the region 12q14-15 targeting the HMGA2 gene, but gene expression data regarding differences between uterine leiomyomas with and those without 12q14-15 aberrations are insufficient. To address the question whether HMGA2 is only upregulated in the 12q14-15 subgroup, the expression of HMGA2 was analyzed in a comprehensive set of leiomyomas (n = 180) including tumors with 12q14-15 chromosomal aberrations (n = 13) and matching myometrial tissues (n = 51) by quantitative RT-PCR. The highest expression levels for HMGA2 were observed in tumors with rearrangements affecting the region 12q14-15, but although HMGA2 is expressed at lower levels in leiomyomas without such aberrations, the comparison between the expression in myomas and matching myometrial tissues indicates a general upregulation of HMGA2 regardless of the presence or absence of such chromosomal abnormalities. The significant (P < 0.05) overexpression of HMGA2 also in the group of fibroids without chromosomal aberrations of the 12q14-15 region suggests a general role of HMGA2 in the development of the disease.

Detection of novel copy number variants in uterine leiomyomas using high-resolution SNP arrays

Uterine leiomyomas (ULs) are benign monoclonal tumors originating from myometrial tissue in the uterus. Genetic pathways that lead to myometrial transformation into leiomyomas are largely unknown. Approximately 40% of ULs are karyotypically abnormal by G-banding; however, the remaining 60% of leiomyomas do not contain cytogenetically visible genomic rearrangements. Recent technological advances such as array based comparative genomic hybridization (array CGH) and dense single nucleotide polymorphism (SNP) arrays have enabled genome-wide scanning for genomic rearrangements missed by karyotype banding analysis. In the current study, we employed a high resolution SNP microarray on 16 randomly selected ULs and normal myometrium samples to detect submicroscopic (<5 Mb) chromosomal aberrations. The SNP array identified gene dosage changes in 56% of the fibroids (9/16), 25% of which (4/16) had aberrations >5 Mb, whereas 31% of which (5/16) contained only submicroscopic copy number changes (<5 Mb). We corroborated 3/5 submicroscopic changes using quantitative PCR, meaning that ultimately, 19% of our samples (3/16) were found to contain only submicroscopic changes. Novel submicroscopic aberrations on chromosomal segments 1q42.13, 11q13.1 and 13q12.13 and large, previously unreported deletions on 15q11.2-q23, 17p-q21.31 and 22q12.2-q12.3 were identified. Previously reported deletions on 1p, 3q, 7q, 13, and chromosome 14q were also noted. RHOU, MAP3K11 and WASF3 gene copy numbers were changed in the subset of leiomyomas with submicroscopic aberrations, and these genes have previously been implicated in tumorigenesis. Our findings support the hypothesis that a significant fraction of ULs without visible cytogenetic changes harbor submicroscopic genomic rearrangements which may in turn contribute to transformation of normal myometrial tissue into leiomyomas.

Murine xenograft model for human uterine fibroids: an in vivo imaging approach

Uterine fibroids are the most prevalent benign tumors in women of reproductive age. The current knowledge on the fibroid disease mechanism has derived from studies of the Eker rat model where a unique germ line defect in the tuberous sclerosis 2 (Tsc2) tumor suppressor gene leads to the development of leiomyosarcoma, leiomyoma, and renal cancer. To study fibroids of human origin, we sought to establish fibroid xenografts in immune-compromised mice. We determined that lentiviral-mediated transduction of a green fluorescence protein (GFP)-luciferase (LUC) fusion gene and bioluminescence-based whole animal imaging allowed for the monitoring of transplanted fibroid cells in mice. We used this in vivo imaging approach to test a series of transplantation protocols and found that only freshly dissociated fibroid cells, but not the fibroid-derived smooth muscle cells grown in ex vivo cultures, can generate stable xenografts in subcutaneous Matrigel implants. Formation of the fibroid-xenografts requires the implantation of 17betaestradiol-releasing pellets in the recipient mice. Furthermore, freshly dissociated myometrial cells do not form xenografts under the experimental conditions. The xenograft protocol developed from this study provides an avenue for investigating the pathogenesis and drug responses of human fibroids.

The catechol-O-methyltransferase (COMT) gene polymorphism and prevalence of uterine fibroids

OBJECTIVE

To assess the possible association between the catechol-O-methyltransferase (COMT) polymorphism and uterine fibroids in Brazilian women.

DESIGN

Case-control study.

SETTING

Department of Gynecology; teaching hospital.

PATIENT(S)

One hundred twenty-four premenopausal women with fibroids, and 193 postmenopausal controls not presenting the disease.

INTERVENTION(S)

The subjects were classified as white or non-white (black and mulatto), and COMT genotypes were determined. DNA was extracted from the uterus of cases and from peripheral blood of controls and submitted to polymerase chain reaction (PCR) and agarose gel electrophoresis.

MAIN OUTCOME MEASURE(S)

The presence of the COMT polymorphism was recorded for all patients, and the frequency and distribution among cases and controls were compared according to race. Binomial log regression models were used to estimate odds-ratios (OR) for uterine volumes of <290 cm(3) (small fibroids) vs. those >290 cm(3) (large fibroids). Potential confounding variables (age, race and parity) were added to the model.

RESULTS

Genotypes positive for the COMT polymorphism (heterozygous or mutant homozygous) were found in 45% of white and 28.9% of non-white women (p = .013) and the polymorphic allele frequencies in these groups were 27.2% and 16.3%, respectively (p = .006). However, there were no clear differences between patients and controls within the white subgroup with regard to the presence of COMT polymorphism-containing genotypes (41.5% vs. 46.0%, respectively) (p = .60), or for the polymorphic allele frequency (26.8% vs. 27.3%, respectively) (p = .92). For non-white women, there were also no differences between cases and controls for the frequency of polymorphic genotypes (28.9% vs. 28.9%, respectively) (p = .995), or for the polymorphic allele frequency (17.8 vs. 14.5, respectively) (p = .565). Estimated OR for small or large fibroids in association with the polymorphic allele revealed a positive association between the allele with lower activity and large fibroids (vs. small) (OR = 3.3; 95% confidence interval [CI] = 1.31-8.46). The adjusted OR was 4.35 (95% confidence interval [CI] = 1.58-11.9).

CONCLUSIONS

The catechol-O-methyltransferase polymorphism is a risk factor for the development of large uterine fibroids in Brazilian women suffering from fibroids.

Association of the CYP17 gene polymorphism with risk for uterine leiomyoma in Brazilian women

BACKGROUND

Uterine leiomyoma is the most common pelvic tumor in women of reproductive age. It is well established that endogenous sex hormones are involved in disease pathogenesis, and polymorphisms in genes encoding enzymes which act in the metabolism of steroid hormones, such as that for cytochrome P450c17alpha enzyme (CYP17), may therefore play a role in fibroid genesis. Variations in this gene have been thought to influence the susceptibility to hormone-related diseases. A single nucleotide polymorphism (T-->C) [rs1042386] in promoter region of CYP17 may alter its transcription. The present study was conducted to investigate the association between this polymorphism and the presence of uterine leiomyoma in Brazilian women.

METHODS

Genotyping of CYP17 was performed in 121 uterine fibroid patients and 120 unaffected women, using polymerase chain reaction and restriction fragment-length polymorphism analysis.

RESULTS

No significant difference in the CYP17 genotype distribution was noted between cases and controls (p = 0.165).

CONCLUSION

These findings suggest that the CYP17 gene polymorphism studied is unlikely to be associated with risk for uterine leiomyoma in Brazilian women.

Incidence, aetiology and epidemiology of uterine fibroids

Uterine fibroids are the most common benign tumour of the female genital tract. However, their true prevalence is probably under-estimated, as the incidence at histology is more than double the clinical incidence. Recent longitudinal studies have estimated that the lifetime risk of fibroids in a woman over the age of 45 years is more than 60%, with incidence higher in blacks than in whites. The cause of fibroids remains unclear and their biology poorly understood. No single candidate gene has been detected for commonly occurring uterine fibroids. However, the occurrence of rare uterine fibroid syndromes, such as multiple cutaneous and uterine leiomyomatosis, has been traced to the gene that codes for the mitochondrial enzyme, fumarate hydratase. Cytogenetic abnormalities, particularly deletions of chromosome 7, which are found in up to 50% of fibroid specimens, seem to be secondary rather than primary events, and investigations into the role of tumour suppressor genes have yielded conflicting results. The key regulators of fibroid growth are ovarian steroids, both oestrogen and progestogen, growth factors and angiogenesis, and the process of apoptosis. Black race, heredity, nulliparity, obesity, polycystic ovary syndrome, diabetes and hypertension are associated with increased risk of fibroids, and there is emerging evidence that familial predisposition to fibroids is associated with a distinct pattern of clinical and molecular features compared with fibroids in families without this prevalence.

Selected metabolic parameters and the risk for uterine fibroids

OBJECTIVE

To analyze the possible association between insulin resistance and dyslipidemia with uterine fibroids, using objective metabolic measurements.

METHOD

A cross-sectional study of 56 women with uterine fibroids (case group) and 20 women without fibroids (control group). Levels of fasting glucose, insulin, C-peptide, sex hormone-binding globulin, and the lipid panel were measured. The short insulin tolerance test was performed. Body mass index, atherogenic index, and the indicator of insulin resistance (Kitt) were also calculated.

RESULTS

Women with fibroids had significantly higher levels of serum HDL-cholesterol compared with control patients (1.8+/-0.3 vs 1.6+/-0.5; P<0.05). Women with fibroids aged 30-45 years had significantly lower LDL-cholesterol levels than comparative control patients (2.9+/-0.7 vs 3.4+/-0.9; P<0.05). A positive correlation between volume of the largest fibroid and serum HDL-cholesterol level was found in women aged 30-45 years. There were no differences in indicators of insulin resistance between the groups.

CONCLUSION

Insulin resistance was not shown to be a risk factor for fibroids. There is a negative association between some parameters of metabolic syndrome and fibroid volume.