Uterine leiomyoma cytogenetics

Unraveling the Molecular Landscape of Uterine Fibroids, Insights into HMGA2 and Stem Cell Involvement

Uterine fibroids are prevalent benign tumors in women that exhibit considerable heterogeneity in clinical presentation and molecular characteristics, necessitating a deeper understanding of their etiology and pathogenesis. HMGA2 overexpression has been associated with fibroid development, yet its precise role remains elusive. Mutations in fibroids are mutually exclusive and largely clonal, suggesting that tumors originate from a single mutant cell. We explored a possible role for HMGA2 overexpression in differentiated myometrial cells, hypothesizing its potential to induce a stem cell-like or dedifferentiating phenotype and drive fibroid development. Myometrial cells were immortalized and transduced with an HMGA2 lentivirus to produce HMGA2hi cells. In vitro stem cell assays were conducted and RNA from HMGA2hi and control cells and fibroid-free myometrial and HMGA2 fibroid (HMGA2F) tissues were submitted for RNA-sequencing. HMGA2hi cells have enhanced self-renewal capacity, decreased proliferation, and have a greater ability to differentiate into other mesenchymal cell types. HMGA2hi cells exhibit a stem cell-like signature and share transcriptomic similarities with HMGA2F. Moreover, dysregulated extracellular matrix pathways are observed in both HMGA2hi cells and HMGA2F. Our findings suggest that HMGA2 overexpression drives myometrial cells to dedifferentiate into a more plastic phenotype and underscore a pivotal role for HMGA2 in fibroid pathogenesis.

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.

A transcriptome-wide association study of uterine fibroids to identify potential genetic markers and toxic chemicals

Uterine fibroid is one of the most prevalent benign tumors in women, with high socioeconomic costs. Although genome-wide association studies (GWAS) have identified several loci associated with uterine fibroid risks, they could not successfully interpret the biological effects of genomic variants at the gene expression levels. To prioritize uterine fibroid susceptibility genes that are biologically interpretable, we conducted a transcriptome-wide association study (TWAS) by integrating GWAS data of uterine fibroid and expression quantitative loci data. We identified nine significant TWAS genes including two novel genes, RP11-282O18.3 and KBTBD7, which may be causal genes for uterine fibroid. We conducted functional enrichment network analyses using the TWAS results to investigate the biological pathways in which the overall TWAS genes were involved. The results demonstrated the immune system process to be a key pathway in uterine fibroid pathogenesis. Finally, we carried out chemical–gene interaction analyses using the TWAS results and the comparative toxicogenomics database to determine the potential risk chemicals for uterine fibroid. We identified five toxic chemicals that were significantly associated with uterine fibroid TWAS genes, suggesting that they may be implicated in the pathogenesis of uterine fibroid. In this study, we performed an integrative analysis covering the broad application of bioinformatics approaches. Our study may provide a deeper understanding of uterine fibroid etiologies and informative notifications about potential risk chemicals for uterine fibroid.

Characteristic of Uterine Rhabdomyosarcoma by Algorithm of Potential Biomarkers for Uterine Mesenchymal Tumor

Background/Aim: Patients with uterine sarcoma comprise 2–5% of all patients with uterine malignancies; however, the morbidity of uterine sarcoma is low compared with that of other gynecological cancers. For many cases, malignant uterine tumors are diagnosed during follow-up of benign uterine leiomyoma. Of the uterine sarcomas, rhabdomyosarcoma is considered a mixed tumor containing components of epithelial cells and mesenchymal cells. Therefore, the onset of primary uterine rhabdomyosarcoma during follow-up of uterine leiomyoma is extremely rare. Rhabdomyosarcoma is a relatively common malignant tumor in children, but rhabdomyosarcoma in adults is extremely rare, accounting for approximately 3% of all patients with soft tissue sarcoma. Rhabdomyosarcoma in children is highly sensitive to chemotherapy and radiation therapy; however, the response to chemotherapy and radiation therapy in adult rhabdomyosarcoma is low and survival in adult rhabdomyosarcoma with metastatic lesions to other organs is approximately 14 months. We experienced a case of pleomorphic rhabdomyosarcoma during the follow-up of a uterine leiomyoma. Materials and Methods: We examined the oncological properties of uterine rhabdomyosarcoma in adults using molecular pathological techniques on tissue excised from patients with uterine leiomyoma. Result: A differential diagnosis was made for this case by molecular pathology, which included candidate biomarkers for uterine smooth muscle tumors. The oncological nature of uterine rhabdomyosarcoma was found to be similar to the oncological properties of uterine leiomyosarcoma. However, in uterine rhabdomyosarcoma, LMP2/β1i-positive cells were clearly observed. Conclusion: It is expected that establishing a diagnostic and treatment method targeting characteristics of mesenchymal tumor cells will lead to the treatment of malignant tumors with a low risk of recurrence and metastasis.

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.

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.

Epigenomic tensor predicts disease subtypes and reveals constrained tumor evolution

Understanding the epigenomic evolution and specificity of disease subtypes from complex patient data remains a major biomedical problem. We here present DeCET (decomposition and classification of epigenomic tensors), an integrative computational approach for simultaneously analyzing hierarchical heterogeneous data, to identify robust epigenomic differences among tissue types, differentiation states, and disease subtypes. Applying DeCET to our own data from 21 uterine benign tumor (leiomyoma) patients identifies distinct epigenomic features discriminating normal myometrium and leiomyoma subtypes. Leiomyomas possess preponderant alterations in distal enhancers and long-range histone modifications confined to chromatin contact domains that constrain the evolution of pathological epigenomes. Moreover, we demonstrate the power and advantage of DeCET on multiple publicly available epigenomic datasets representing different cancers and cellular states. Epigenomic features extracted by DeCET can thus help improve our understanding of disease states, cellular development, and differentiation, thereby facilitating future therapeutic, diagnostic, and prognostic strategies.

Leistico et al. apply tensor decomposition and classification methods to integrate information from hierarchical heterogenous epigenomic datasets and identify histone modification patterns that discriminate disease conditions, tissue types, and differentiation states. Leiomyomas are shown to possess alterations in distal enhancers and large-scale regions confined to chromatin contact domains.

Intravenous leiomyomatosis is inclined to a solid entity different from uterine leiomyoma based on RNA-seq analysis with RT-qPCR validation

Introduction

Intravenous leiomyomatosis (IVL) is currently regarded as a special variant of the common uterine leiomyoma (LM). Though IVL shows a similar histological morphology to LM, IVL is characterized by unique intravenous growth patterns and low‐grade malignant potential, which are quite different from LM. There are currently few studies underlying the molecular alterations of IVL, though this information is important for understanding the pathogenesis of the disease, and for identifying potential biomarkers.

Method

We carried out a high‐throughput whole transcriptome sequencing of tumor and normal tissue samples from five IVL patients and five LM patients and compared the differentially expressed genes (DEGs) between IVL and leiomyoma. We performed multiple different enrichment and target analyses, and the expression of selected DEGs was validated using RT‐qPCR in formalin‐fixed samples.

Results

Our study identified substantial different genes and pathways between IVL and LM, and functional enrichment analyses found several important pathways, such as angiogenesis and antiapoptosis pathways, as well as important related genes, including SH2D2A, VASH2, ADAM8, GATA2, TNF, and the lncRNA GATA6‐AS1, as being significantly different between IVL and LM (P = .0024, P = .0195, P = .0212, P = .0435, P = .0401, and P = .0246, respectively). CXCL8, LIF, CDKN2A, BCL2A1, COL2A1, IGF1, and HMGA2 were also differently expressed between IVL and LM groups, but showed no statistical difference (P = .2409, P = .1773, P = .0596, P = .2737, P = .1553, P = .1045, and P = .1847, respectively) due to the large differences among individuals. Furthermore, RT‐qPCR results for five selected DEGs in IVL tissues and adjacent nontumor tissues were mainly consistent with our sequencing results.

Conclusion

Our results indicated that IVL may be a solid entity that is unique and different from LM, proving consistent with previous studies. Furthermore, we identified DEGs, particularly within angiogenesis and antiapoptosis pathway‐related genes that may play crucial roles in the development and pathogenesis of IVL and may be potential specific biomarkers.

Molecular cytogenetic pilot study on pleomorphic adenomas of salivary glands

Pleomorphic adenomas (PAs) of salivary glands are the most frequent entity of solid parotid tumors. Nonetheless, their genetics is not yet well understood. Thus, the current study characterized 14 PAs using a unique combination of cytogenetic, molecular cytogenetic and/or molecular karyotyping based approaches. The current study applied G-banding based on trypsin treatment and Giemsa-staining in peripheral blood and tumor tissue. Additionally, fluorescence in situ hybridization was performed using whole chromosome painting or centromeric probes. Array-based comparative genomic hybridization was also conducted. In 5 of 14 cases, chromosomal and/or submicroscopic alterations were characterized. Balanced and unbalanced translocations, loss or gain of whole chromosomes and submicroscopic copy number alterations were detected. Furthermore, the first case of a so-called ‘jumping translocation’ in a PA was reported. The genes twist-related protein 1 and distal-less homeobox 5 were also involved in copy number variations in two PAs. In conclusion, approaches utilized in the current study are highly suited to characterize the genetic constitution of PAs.

Clinical, pathologic, cytogenetic, and molecular profiling in self-identified black women with uterine leiomyomata

Black women are disproportionately affected by uterine leiomyomata (UL), or fibroids, compared to other racial groups, having a greater lifetime risk of developing UL and an earlier age of diagnosis. In order to elucidate molecular and genetic mechanisms responsible for the increased prevalence and morbidity associated with UL in black women, clinical, pathologic, cytogenetic, and select molecular profiling (MED12 mutation analysis) of 75 self-reported black women undergoing surgical treatment for UL was performed. Our observations are broadly representative of previous cytogenetic studies of UL: karyotypically abnormal tumors were detected in 30.7% of women and 17.4% of analyzed tumors. No notable association was observed between race and increased occurrence of cytogenetic abnormalities that might contribute to any population-specific morbidity or prevalence rate. Our data on MED12 mutation analyses (73.2% of tumors harbored a MED12 mutation) provide additional support for a significant role of MED12 in tumorigenesis. Although the effect of MED12-mediated tumorigenesis appears significant irrespective of race, other genetic events such as the distribution of karyotypic abnormalities appear differently in black women. This case series indicates that presently recognized genetic and molecular characteristics of UL do not appear to explain the increased prevalence and morbidity of UL in black women.

Genetics and genomics of breast fibroadenomas

Fibroadenomas of the breast are benign fibroepithelial tumours most frequently encountered in women of reproductive age, although they may be diagnosed at any age. The fibroadenoma comprises a proliferation of both stromal and epithelial components. The mechanisms underlying fibroadenoma pathogenesis remain incompletely understood. In the clinical setting, distinguishing cellular fibroadenomas from benign phyllodes tumours is a common diagnostic challenge due to subjective histopathological criteria and interobserver differences. Recent sequencing studies have demonstrated the presence of highly recurrent mutations in fibroadenomas, and also delineated the genomic landscapes of fibroadenomas and the closely related phyllodes tumours, revealing differences at the gene level, which may be of potential adjunctive diagnostic use. The present article provides an overview of key studies uncovering genetic and genomic abnormalities in fibroadenomas, from initial karyotype reports revealing myriad cytogenetic aberrations to next-generation sequencing-based approaches that led to the discovery of highly recurrent MED12 mutations. A thorough understanding of these abnormalities is important to further elucidate the mechanisms by which fibroadenomas arise and to refine diagnostic assessment of this very common tumour.

Characterization of MED12, HMGA2, and FH alterations reveals molecular variability in uterine smooth muscle tumors

Uterine smooth muscle tumors range from benign leiomyomas to malignant leiomyosarcomas. Based on numerous molecular studies, leiomyomas and leiomyosarcomas mostly lack shared mutations and the majority of tumors are believed to develop through distinct mechanisms. To further characterize the molecular variability among uterine smooth muscle tumors, and simultaneously insinuate their potential malignant progression, we examined the frequency of known genetic leiomyoma driver alterations (MED12 mutations, HMGA2 overexpression, biallelic FH inactivation) in 65 conventional leiomyomas, 94 histopathological leiomyoma variants (18 leiomyomas with bizarre nuclei, 22 cellular, 29 highly cellular, and 25 mitotically active leiomyomas), and 51 leiomyosarcomas. Of the 210 tumors analyzed, 107 had mutations in one of the three driver genes. No tumor had more than one mutation confirming that all alterations are mutually exclusive. MED12 mutations were the most common alterations in conventional and mitotically active leiomyomas and leiomyosarcomas, while leiomyomas with bizarre nuclei were most often FH deficient and cellular tumors showed frequent HMGA2 overexpression. Highly cellular leiomyomas displayed the least amount of alterations leaving the majority of tumors with no known driver aberration. Our results indicate that based on the molecular background, histopathological leiomyoma subtypes do not only differ from conventional leiomyomas, but also from each other. The presence of leiomyoma driver alterations in nearly one third of leiomyosarcomas suggests that some tumors arise through leiomyoma precursor lesion or that these mutations provide growth advantage also to highly aggressive cancers. It is clinically relevant to understand the molecular background of various smooth muscle tumor subtypes, as it may lead to improved diagnosis and personalized treatments in the future.

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.

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.

Microchimeric Cells, Sex Chromosome Aneuploidies and Cancer

The phenomenon of feta-maternal microchimerisms inspires numerous questions. Many questions remain to be answered regarding this new avenue of genetics. The X and Y chromosomes have been associated with malignancy in different types of human tumors. We aimed to investigate the numerical aberrations of chromosomes X and Y in lung cancer (LC) and bladder cancer (BC) and review recent evidence for possible roles of microchimeric cells (McCs) in these cancers. We carried out cytogenetic analysis of the tumor and blood sampling in 52 cases of people with BC and LC, and also with 30 healthy people. A total of 48 (92.3 %) of the patients revealed sex chromosome aneuploidies (SCAs). A total SCAs was found in 9.8 % of 2282 cells that were analyzed as one or more cells in each case. The 68 and 95 SCAs were found in the 1952 (8.4 %) cells in peripheral blood, and 41 and 19 SCAs in the 330 (18.2 %) cells in the tumoral tissues respectively. There was a significant difference in the frequencies of SCAs between the patients and the control groups determined by the Fischer's Exact Test (p < 0.0001). The frequencies of SCAs were higher in the tumoral tissues than in the blood (p < 0.0001). There was a significant difference in the frequencies of SCAs between the tumor and blood tissues, and this was higher in the tumor tissue (p < 0.0001). In general, 78.9 % (41) of the 52 patients with LC and BC had X and Y chromosome monosomies. Largely a Y chromosome loss was present in 77.8 % of the men, and the 47, XXY karyotype was found in 33.3 % of them. The second most common SCA was monosomy X, and was found in 71.4 % of the women. McCs were observed in 26.9 % of the 52 patients, and the frequencies of McCs were higher in the blood than in the tissues (p < 0.0001). XY cells were identified in the lung and bladder tissues of the women who had been pregnant with boys, but not in those who had not. There was a significant difference in the frequencies of McCs between the LC and BC patients (p < 0.0005). We speculate that the microchimerism could have a general beneficial role in cancer, in which some sites may not be evident because of an allogeneic maternal immune reaction that hastens cancer development. A further understanding of McCs may help in anticipating its implications in cancer. Our results may suggest that SCAs may be contributing factors in the development of LC and BC, and aneuploidies of X and Y chromosomes play a role in the pathogenesis of cancers.

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.

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.

Chromosome imbalances and alterations in the p53 gene in uterine myomas from the same family members: familial leiomyomatosis in Turkey

Uterine leiomyomas (UL) are extremely common neoplasms in women of reproductive age, and are associated with a variety of characteristic choromosomal aberrations (CAs). The p53 gene has been reported to play a crucial role in suppressing the growth of a variety of cancer cells. Therefore, the present study investigated the effects of CAs and the p53 gene on ULs. We performed cytogenetic analysis by G-banding in 10 cases undergoing myomectomy or hysterectomy. Fluorescence in situ hybridization (FISH) with a p53 gene probe was also used on interphase nuclei to screen for deletions. In patients, CAs were found in 23.4% of 500 cells analysed, significantly more frequent than in the control group (p<0.001). In the patients, 76% of the abnormalities were structural aberrations (deletions, translocations and breaks), and only 24% were numerical. Deletions were the most common structural aberration observed in CAs. Among these CAs, specific changes in five loci 1q11, 1q42, 2p23, 5q31 and Xp22 have been found in our patients and these changes were not reported previously in UL. The chromosome breaks were more frequent in cases, from high to low, 1, 2, 6, 9, 3, 5, 10 and 12. Chromosome 22, X, 3, 17 and 18 aneuploidy was observed to be the most frequent among all numerical aberrations. We observed a low frequency of p53 losses (2-11%) in our cases. The increased incidence of autosomal deletions, translocations, chromatid breaks and aneuploidy, could contribute to the progression of the disease along with other chromosomal alterations.

De novo 13q13.3-21.31 deletion involving RB1 gene in a patient with hemangioendothelioma of the liver

Interstitial deletions of the long arm of chromosome 13 (13q) are related with variable phenotypes, according to the size and the location of the deleted region. The main clinical features are moderate/severe mental and growth retardation, cranio-facial dysmorphism, variable congenital defects and increased susceptibility to tumors. Here we report a 3-year-old girl carrying a de novo 13q13.3-21.32 interstitial deletion. She showed developmental delay, growth retardation and mild dysmorphism including curly hair, high forehead, short nose, thin upper lip and long philtrum. An abnormal mass was surgically removed from her liver resulting in a hemangioendothelioma. Array analysis allowed us to define a deleted region of about 27.87 Mb, which includes the RB1 gene. This is the first report of a 13q deletion associated with infantile hemangioendothelioma of the liver.

Exomic landscape of MED12 mutation-negative and -positive uterine leiomyomas

Uterine leiomyomas are extremely common tumors originating from the smooth muscle cells of myometrium. We recently reported recurrent somatic mutations in mediator complex subunit 12 (MED12) in the majority of these lesions, and analyzed chromosomal abnormalities in leiomyomas by whole-genome sequencing. The aim of our study was to examine in detail uterine leiomyoma exomes, to search for driver mutations in MED12 mutation-negative leiomyomas and to scrutinize MED12 mutation-positive leimyomas for additional contributing mutations. We analyzed whole exome sequencing data of 27 uterine leiomyomas (12 MED12 mutation-negative and 15 MED12 mutation-positive) and their paired normal myometrium. We searched for genes, which would be recurrently mutated. No such genes were identified in MED12 mutation-negative uterine leiomyomas. Similarly, MED12 mutation-positive leiomyomas displayed no additional recurrent changes. The complete lack of novel driver point mutations in the examined series highlights the unique role of MED12 mutations in genesis of uterine leiomyomas, and suggests that these mutations alone may be sufficient for tumor development. Additional factors that cannot be detected by exome sequencing, such as somatic structural rearrangements, epigenetic events and intronic variants, are likely to have a particular impact to the development of MED12 wild-type lesions.

Characterization of uterine leiomyomas by whole-genome sequencing

BACKGROUND

Uterine leiomyomas are benign but affect the health of millions of women. A better understanding of the molecular mechanisms involved may provide clues to the prevention and treatment of these lesions.

METHODS

We performed whole-genome sequencing and gene-expression profiling of 38 uterine leiomyomas and the corresponding myometrium from 30 women.

RESULTS

Identical variants observed in some separate tumor nodules suggested that these nodules have a common origin. Complex chromosomal rearrangements resembling chromothripsis were a common feature of leiomyomas. These rearrangements are best explained by a single event of multiple chromosomal breaks and random reassembly. The rearrangements created tissue-specific changes consistent with a role in the initiation of leiomyoma, such as translocations of the HMGA2 and RAD51B loci and aberrations at the COL4A5-COL4A6 locus, and occurred in the presence of normal TP53 alleles. In some cases, separate events had occurred more than once in single tumor-cell lineages.

CONCLUSIONS

Chromosome shattering and reassembly resembling chromothripsis (a single genomic event that results in focal losses and rearrangements in multiple genomic regions) is a major cause of chromosomal abnormalities in uterine leiomyomas; we propose that tumorigenesis occurs when tissue-specific tumor-promoting changes are formed through these events. Chromothripsis has previously been associated with aggressive cancer; its common occurrence in leiomyomas suggests that it also has a role in the genesis and progression of benign tumors. We observed that multiple separate tumors could be seeded from a single lineage of uterine leiomyoma cells. (Funded by the Academy of Finland Center of Excellence program and others.).

Loss of the repressor REST in uterine fibroids promotes aberrant G protein-coupled receptor 10 expression and activates mammalian target of rapamycin pathway

Uterine fibroids (leiomyomas) are the most common tumors of the female reproductive tract, occurring in up to 77% of reproductive-aged women, yet molecular pathogenesis remains poorly understood. A role for atypically activated mammalian target of rapamycin (mTOR) pathway in the pathogenesis of uterine fibroids has been suggested in several studies. We identified that G protein-coupled receptor 10 [GPR10, a putative signaling protein upstream of the phosphoinositide 3-kinase-protein kinase B/AKT-mammalian target of rapamycin (PI3K/AKT-mTOR) pathway] is aberrantly expressed in uterine fibroids. The activation of GPR10 by its cognate ligand, prolactin releasing peptide, promotes PI3K-AKT-mTOR pathways and cell proliferation specifically in cultured primary leiomyoma cells. Additionally, we report that RE1 suppressing transcription factor/neuron-restrictive silencing factor (REST/NRSF), a known tumor suppressor, transcriptionally represses GPR10 in the normal myometrium, and that the loss of REST in fibroids permits GPR10 expression. Importantly, mice overexpressing human GPR10 in the myometrium develop myometrial hyperplasia with excessive extracellular matrix deposition, a hallmark of uterine fibroids. We demonstrate previously unrecognized roles for GPR10 and its upstream regulator REST in the pathogenesis of uterine fibroids. Importantly, we report a unique genetically modified mouse model for a gene that is misexpressed in uterine fibroids.

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.

Whole exome sequencing in a random sample of North American women with leiomyomas identifies MED12 mutations in majority of uterine leiomyomas

Uterine leiomyomas (uterine fibroids) arise from smooth muscle tissue in the majority of women by age 45. It is common for these clonal tumors to develop from multiple locations within the uterus, leading to a variety of symptoms such as pelvic pain, abnormal uterine bleeding, and infertility. We performed whole exome sequencing on genomic DNA from five pairs of leiomyomas and corresponding normal myometrium to determine genetic variations unique to leiomyomas. Whole exome sequencing revealed that the gene encoding transcription factor MED12 (Mediator complex subunit 12) harbored heterozygous missense mutations caused by single nucleotide variants in highly conserved codon 44 of exon 2 in two of five leiomyomas. Sanger re-sequencing of MED12 among these five leiomyomas confirmed the two single nucleotide variants and detected a 42 base-pair deletion within exon 2 of MED12 in a third leiomyoma. MED12 was sequenced in an additional 143 leiomyomas and 73 normal myometrial tissues. Overall, MED12 was mutated in 100/148 (67%) of the genotyped leiomyomas: 79/148 (53%) leiomyomas exhibited heterozygous missense single nucleotide variants, 17/148 (11%) leiomyomas exhibited heterozygous in-frame deletions/insertion-deletions, 2/148 (1%) leiomyomas exhibited intronic heterozygous single nucleotide variants affecting splicing, and 2/148 (1%) leiomyomas exhibited heterozygous deletions/insertion-deletions spanning the intron 1-exon 2 boundary which affected the splice acceptor site. Mutations were not detected in MED12 in normal myometrial tissue. MED12 mutations were equally distributed among karyotypically normal and abnormal uterine leiomyomas and were identified in leiomyomas from both black and white American women. Our studies show an association between MED12 mutations and leiomyomas in ethnically and racially diverse American women.

Paratesticular leiomyoma with a der(14)t(12;14)(q15;q24)

While uterine leiomyomas are among the most common and best cytogenetically characterized solid tumors, leiomyomas at other sites are rare. Only two karyotypically abnormal leiomyomas in males have been reported to date, both of them with unspecific chromosome aberrations. We recently analyzed by G-banding a paratesticular leiomyoma, a tumor type not cytogenetically examined before, and found the pseudodiploid karyotype 46,XY,der(5)t(5;14)(q31;q24),der(14)t(12;14)(q15;q24). The leiomyoma cells demonstrated strong immunohistochemical nuclear expression of the HMGA2 protein, supporting a role of HMGA2 as the target gene in 12q14∼15 rearrangements. In uterine leiomyomas, the t(12;14)(q15;q24) is the most frequent translocation leading to overexpression of HMGA2, therefore it seems that a common pathogenetic pathway exists for benign smooth muscle tumors of both the female and male reproductive organs. The finding of this abnormality may help identify a scrotal tumor of uncertain biologic potential but with smooth muscle differentiation as benign.

Cerebral cavernous malformations: from genes to proteins to disease

Over the past half century molecular biology has led to great advances in our understanding of angio- and vasculogenesis and in the treatment of malformations resulting from these processes gone awry. Given their sporadic and familial distribution, their developmental and pathological link to capillary telangiectasias, and their observed chromosomal abnormalities, cerebral cavernous malformations (CCMs) are regarded as akin to cancerous growths. Although the exact pathological mechanisms involved in the formation of CCMs are still not well understood, the identification of 3 genetic loci has begun to shed light on key developmental pathways involved in CCM pathogenesis. Cavernous malformations can occur sporadically or in an autosomal dominant fashion. Familial forms of CCMs have been attributed to mutations at 3 different loci implicated in regulating important processes such as proliferation and differentiation of angiogenic precursors and members of the apoptotic machinery. These processes are important for the generation, maintenance, and pruning of every vessel in the body. In this review the authors highlight the latest discoveries pertaining to the molecular genetics of CCMs, highlighting potential new therapeutic targets for the treatment of these lesions.

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.

Fusion of HMGA2 to COG5 in uterine leiomyoma

Uterine leiomyomas are smooth muscle tumors most commonly seen in middle-aged women. Approximately 10% of these tumors contain rearrangements of the chromatin-remodeling gene HMGA2 at the chromosome band 12q14.3. Herein, we report on a uterine leiomyoma with a novel HMGA2 fusion gene. A 44-year-old woman presented with a 20-cm mass uterine leiomyoma. From a histological standpoint, the tumor exhibited extensive hyalinization, very low mitotic activity (<1/10 HPH), and no cytologic atypia. Smooth muscle differentiation was confirmed by the expression of smooth muscle actin and desmin. Standard cytogenetic analysis showed the reciprocal translocation t(7;12)(q31.2;q14.3). Fluorescence in situ hybridization analysis confirmed a balanced rearrangement of the HMGA2 locus in 80% of the cells. 3'RACE reverse-transcription polymerase chain reaction identified the fusion of HMGA2 exon 4 to the COG5 locus on 7q31 (component of oligomeric golgi complex 5 isoform). The fusion sequence is predicted to encode a 96-amino acid chimeric protein that retains all three DNA-binding domains (AT hooks) of HMGA2, but that is shorter than the original HMGA2 protein. Since the general structure of the fusion gene is similar to other previously described HMGA2 fusions, its biologic activity is predicted to be likely similar.

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.

Uterine innervation in fibroids: A qualitative study

This study describes the innervation of uterine fibroids in a retrospective survey of archived material. A total of 24 uteri containing fibroids were identified; four nulliparous uteri with single large fundal fibroids (200 - 320 g) and 20 multiparous uteri with one, or more, fibroids (80 - 230 g). Tissue blocks from the uterine isthmus and the fibroids, were identified, sectioned and stained for nerves with anti-S100 using a standard immunohistochemical regimen. Normal uterine innervation includes concentrations of nerves in the subserosal layer and at the endometrial-myometrial interface with sparse neurovascular bundles distributed throughout the myometrial stroma. Nulliparous uteri with single large fibroids demonstrated relatively normal patterns of innervation with nerves distributed throughout the stroma of the fibroid. In multiparous uteri with fibroids, there were no nerves detectable in the substance of the fibroids. Increased numbers of nerve fibres were observed in the pseudo-capsule of some fibroids and may reflect compression of normal myometrial tissue and their contained nerves, or, a minor degree of nerve fibre proliferation. This study demonstrates that fibroids in multiparous uteri do not contain nerves. Single, large nulliparous fibroids situated at the uterine fundus appear to contain relatively normal patterns of innervation.

Molecular and cytogenetic characterization of plexiform leiomyomata provide further evidence for genetic heterogeneity underlying uterine fibroids

The plexiform variant of uterine leiomyomata (UL) is named for its ribbons or nests of smooth muscle cells that have a rounded, epithelioid shape caused by their entrapment in abundant extracellular matrix. Plexiform UL are currently classified as epithelioid smooth muscle tumors alongside the less predictable, "true" epithelioid tumors (ie, leiomyoblastomas). Karyotypes of six plexiform UL cases were studied, and their abnormalities were found to differ from those of leiomyoblastomas. Analyses using real-time polymerase chain reaction, immunohistochemistry, and fluorescence in situ hybridization demonstrated elevated mRNA and protein levels of the architectural factor HMGA2 and, in some cases, increased DNA copy number. Four of these plexiform UL were profiled with Affymetrix human U133 plus 2.0 expression arrays. Cluster analysis using genes previously shown to discriminate benign and malignant uterine smooth muscle tissues revealed that the plexiform tumors form an isolated group in the benign branch. This is in contrast to an earlier finding in which another variant, cellular UL characterized by loss of a portion of the short arm of chromosome 1, clustered with malignant leiomyosarcomas. These results provide additional evidence of genetic heterogeneity underlying UL of various histological types. We further suggest that plexiform UL should be classified among tumors with extensive hyalinization rather than with "true" epithelioid smooth muscle neoplasms.

Long-term use of progestogens--effects on endometriosis, adenomyosis and myomas

Oral progestins, without an estrogen component, have been reported to be effective in the treatment of endometriosis, but not adenomyosis or myomas. The mode of action on the target tissue is still a matter of debate. Besides the importance of estrogens for the development and growth of endometriosis and myomas, progesterone seems to play an important role in the modulation of mitotic activity, local growth factors and growth factor receptors, as well as other paracrine mechanisms. Earlier studies postulated activities via steroid receptor mechanisms, as observed in the uterine mucosa and myometrium. Recent studies, however, have raised some doubts about this hypothesis. Effective new therapies for endometriosis have been introduced during the last 30 years and progestins now have a place in the symptomatic management of pain, bleeding and other symptoms caused by endometriosis, adenomyosis or myoma, particularly when long-term medication is indicated or when repeated courses of treatment are acceptable.

High Frequency of JAZF1-JJAZ1 Gene Fusion in Endometrial Stromal Tumors With Smooth Muscle Differentiation by Interphase FISH Detection

The most common cytogenetic alteration observed in low-grade endometrial stromal tumors (EST) is the t(7;17)(p15;q21) translocation, resulting in the fusion of the JAZF1 and JJAZ1 genes. By reverse-transcription polymerase chain reaction, the translocation has been detected overall in one-third of ESTs, but only rarely in its variants. The purpose of this study was to develop a fluorescence in situ hybridization assay for detection of this translocation using archival paraffin-embedded samples of ESTs with smooth muscle differentiation and to assess the nature of the smooth muscle component of these tumors. Representative paraffin blocks of 9 endometrial stromal nodules and 1 low-grade endometrial stromal sarcoma were collected for the study. In 1 case, the block selected also contained areas of sex cordlike differentiation. A fluorescence in situ hybridization probe set was designed to detect the t(7;17)(p15;q12) on tissue sections. Six out of 10 collected ESTs were assessable. Fusion signals were detected in 3 out of 6 cases (50%) in both the conventional endometrial stromal and the smooth muscle components of the tumors. The tumor sample with sex cordlike differentiation harbored the fusion signal in all the 3 components. Our results support the contention that the endometrial stromal and smooth muscle components of these tumors have the same origin, either from a common precursor cell with pluripotential differentiation or from endometrial stromal cells that have undergone smooth muscle metaplasia. Our results indicate that the detection of this chromosomal abnormality can be used to diagnose ESTs with smooth muscle differentiation when the smooth muscle component is predominant.

The genetic heterogeneity of uterine leiomyomata

Research investigating the genetics of UL has already been successful in gathering epidemiologic evidence for heritability, establishing the clonal and mosaic nature of these tumors, correlating genotypic and phenotypic characteristics, defining cytogenetic subgroups, and identifying specific genes involved in tumorigenesis. Although UL are known to be benign tumors, the impact they have on the lives of so many women can only be described as "malignant". For this reason, continuing the quest to ascertain the genes, functions, and mechanisms integral to UL development is absolutely imperative. Genetic tests for personalized medical management of women with fibroids is at the threshold for providing the most appropriate treatments (Fig. 3), and combined with developing less invasive therapies portends a brighter future for a major health problem for women.

Analysis of Allelic Loss as an Adjuvant Tool in Evaluation of Malignancy in Uterine Smooth Muscle Tumors

Uterine smooth muscle tumors of uncertain malignant potential (STUMPs) are difficult both from the diagnostic and patient management standpoint because they cannot be classified as benign or malignant by conventional histologic criteria. This study's aim was to determine the diagnostic utility of allelic imbalance (AI) analysis in uterine smooth muscle tumors. Using microdissection and genotyping, we tested 5 leiomyomas, 6 STUMPs, and 10 leiomyosarcomas with follow-up for AI across a panel of seven tumor suppressor genes (p16, p21, p53, VHL, XRCC3, RB, and NM-23). None of the 6 patients with STUMP experienced recurrent disease, whereas 8 of the 10 patients diagnosed with leiomyosarcoma died of disease at follow-up. The mean frequency of allelic loss (FAL) for leiomyomas (18%) was not significantly different from that of STUMPs (21%) (P = 1), whereas leiomyosarcomas displayed a significantly higher FAL (52%) than both leiomyomas (P = 0.001) and STUMPs (P = 0.002). Loss of NM-23, a reported tumor metastasis suppressor gene, was found only in leiomyosarcomas (5 of 9, or 56%), and 4 of 5 (80%) of these were the only cases that demonstrated distant metastases (P = 0.04). Additionally, an FAL of >50% correlated with both NM-23 loss (P = 0.008) and distant metastatic disease (P = 0.04). In conclusion, leiomyomas and STUMPs displayed similar mean FALs and all were clinically benign, whereas uterine leiomyosarcomas had significantly higher frequencies of allelic loss than both leiomyomas and STUMPs. Molecular profiling may thus provide a valuable tool in assessment of malignancy in uterine smooth muscle tumors. Additionally, NM-23 is a promising candidate gene for determination of metastatic potential in these tumors.

Independent clonal origin of multiple uterine leiomyomas that was determined by X chromosome inactivation and microsatellite analysis

OBJECTIVE

In an attempt to clarify the clonality and genetic relationships that are involved in the tumorigenesis of uterine leiomyomas, we used a total of 43 multiple leiomyomas from 14 patients and analyzed the allelic status with 15 microsatellite markers and X chromosome inactivation analysis.

STUDY DESIGN

We have used a set of 15 microsatellite polymorphism markers mapped on 3q, 7p, 11, and 15q by automated analysis. The X chromosome inactivation was evaluated by the methylation status of the X-linked androgen receptor gene.

RESULTS

Loss of heterozygosity analysis showed a different pattern in 7 of the 8 cases with allelic loss for at least 1 of 15 microsatellite markers that were analyzed. A similar loss of heterozygosity findings at 7p22-15 was detected in 3 samples from the same patient. X chromosome inactivation analysis demonstrated the same inactivated allele in all tumors of the 9 of 12 informative patients; different inactivation patterns were observed in 3 cases.

CONCLUSION

Our data support the concept that uterine leiomyomas are derived from a single cell but are generated independently in the uterus. Loss of heterozygosity findings at 7p22-15 are consistent with previous data that suggested the relevance of chromosomal aberrations at 7p that were involved in individual uterine leiomyomas.

7q deletion mapping and expression profiling in uterine fibroids

Uterine fibroids are some of the most common tumours of females, but relatively little is known about their molecular basis. Several studies have suggested that deletions on chromosome 7q could have a role in fibroid formation. We analysed 165 sporadic uterine fibroids to define a small 3.2 megabase (Mb) commonly deleted region on 7q22.3-q31.1, flanked by clones AC005070 and AC007567. We also used oligonucleotide microarrays to compare the expression profiles of 10 samples of normal myometrium and 15 fibroids, nine of which displayed 7q-deletions. Activating transcription factor 3, patched homolog (Drosophila), homeo box A5, death-associated protein kinase 1, and retinoic acid receptor responder 3 were downregulated, and excision repair crosscomplementing 3, transcription factor AP-2 gamma and protein kinase C beta 1 were upregulated in fibroids. New pathways were discovered related to fibroid formation. The presence or absence of 7q-deletions did not dramatically affect the global expression pattern of the tumours; changes, however, were observed in genes related to vesicular transport and nucleic acid binding.

Gene expression studies provide clues to the pathogenesis of uterine leiomyoma: new evidence and a systematic review

BACKGROUND

Uterine leiomyomas are extremely common and a major cause of pelvic pain, bleeding, infertility, and the leading indication for hysterectomy. Familial and epidemiological studies provide compelling evidence that genetic alterations play an important role in leiomyoma development.

METHODS

Using Affymetrix U133A GeneChip we analysed expression profiles of 22,283 genes in paired samples of leiomyoma and adjacent normal myometrium. We compared our results with previously published data on gene expression in uterine leiomyoma and identified the overlapping gene alterations.

RESULTS

We detected 80 genes with average differences of > or = 2-fold and false discovery rates of < 5% (14 overexpressed and 66 underexpressed). A comparative analysis including eight previous gene expression studies revealed eight prominent genes (ADH1, ATF3, CRABP2, CYR61, DPT, GRIA2, IGF2, MEST) identified by at least five different studies, eleven genes (ALDH1, CD24, CTGF, DCX, DUSP1, FOS, GAGEC1, IGFBP6, PTGDS, PTGER3, TYMS) reported by four studies, twelve genes (ABCA, ANXA1, APM2, CCL21, CDKN1A, CRMP1, EMP1, ESR1, FY, MAP3K5, TGFBR2, TIMP3) identified by three studies, and 40 genes reported by two different studies.

CONCLUSIONS

Review of gene expression data revealed concordant changes in genes regulating retinoid synthesis, IGF metabolism, TGF-beta signaling and extracellular matrix formation. Gene expression studies provide clues to the relevant pathways of leiomyoma development.

High mobility group I-C protein in astrocytoma and glioblastoma

High mobility group I-C (HMGI-C) protein is a non-histone DNA-binding factor that organizes active chromatin. This protein is expressed during the limited phase of embryonic development and may regulate the expression of genes critical for embryonic cell growth and differentiation. As embryonic mechanisms are also known to play a role in the development of some neoplasms, we investigated human brain tumors for the expression of HMGI-C to determine its role in the differentiation of glial cell tumors. Immunohistochemical analysis revealed HMGI-C in all of the low-grade astrocytomas, in 2 of 3 anaplastic astrocytomas (grade 3), but in only one of 8 glioblastomas. The results were confirmed at the mRNA level by nested reverse-transcription polymerase chain reaction analyses. Loss of HMGI-C was also demonstrated in a case of glioblastoma transformed from the low-grade astrocytoma strongly expressing HMGI-C protein. These results suggest that HMGI-C may be involved in the differentiation of glial tumor cells, and that loss of HMGI-C expression may contribute to the transformation of low-grade astrocytoma into glioblastoma.

Expression profile of tuberin and some potential tumorigenic factors in 60 patients with uterine leiomyomata

Human uterine leiomyomata are the most common tumors in women of reproductive age. The pathogenesis of leiomyomata remains unknown. An animal model of Eker rats with deleted tuberous sclerosis complex gene 2 (tuberin) shows increased incidence of leiomyomata. The role of tuberin in human leiomyomata is unknown. In this study, we designed a tissue microarray with tissue cores of leiomyomata and the matched myometrium from 60 hysterectomy specimens. We examined the expression of tuberin and tuberous sclerosis complex gene 1 product hamartin, proteins of the insulin-signaling pathway, steroid receptors and some of their cofactors, and human mobility group gene A2 by immunohistochemistry. We found that nearly half of the cases displayed either reduction or loss of tuberin in leiomyomata compared with matched normal myometrium. No change of hamartin was noted. Furthermore, a significant reduction of glucocorticoid receptor was found in leiomyomata with reduced tuberin. The proteins insulin like growth factor 1, insulin-like growth factor receptor beta, AKT kinase, and phosphatidylinositol 3-kinase were upregulated. Nearly half of leiomyomata show upregulation of human mobility group gene A2, along with the steroid receptor cofactors. Our findings suggest that there are two broad groups of uterine leiomyomata. One group is associated with an alteration of tuberin and glucocorticoid receptor. The other group is associated with upregulation of human mobility group gene A2 and steroid receptor cofactors.

Uterine leiomyomata with deletions of Ip represent a distinct cytogenetic subgroup associated with unusual histologic features

Cytogenetic analysis of uterine leiomyomata (UL) shows that about 40% of these benign tumors have simple, clonal chromosomal rearrangements. In contrast, their presumed malignant counterpart, leiomyosarcomas (LMSs), typically has complex numerical and structural abnormalities. Several variants of benign uterine smooth-muscle tumors are defined by histologic phenotypes intermediate between typical UL and LMS, and currently, little is known about their cytogenetic and molecular genetic features. From a subset of more than 800 karyotyped ULs, we identified a group of nine cases exhibiting near-diploid karyotypes with loss of almost the entire short (p) arm of chromosome 1 [i.e., del(1)(p11p36)]. Loss of 1p was often associated with other aberrations, particularly loss of chromosomes 19 and/or 22. Of eight UL for which the histologic diagnosis was known, four were diagnosed as cellular UL; one displayed both hypercellularity and nuclear atypia. Loss of heterozygosity (LOH) analysis for chromosomal regions 1p36.23 and 1p21.1 demonstrated allelic loss for either a portion or the majority of 1p in 5 of 10 additional archival UL diagnosed with either cellular or atypical histology. RNA from two UL with loss of 1p was profiled using Affymetrix GeneChips, and those profiles were compared to our previously reported smooth-muscle tumor expression profile. The transcriptional profiles of tumors with 1p deletion were more similar to those of leiomyosarcoma than to profiles of myometrium and UL, as determined by hierarchical cluster analysis. Comparison of the transcriptional profiles for UL with and without 1p-- revealed 53 genes with differential regulation. Loss of 1p appears to define a subgroup of UL distinct from those previously recognized. Furthermore, 1p-- appears to be associated with a specific histologic phenotype. The similarity between the transcriptional profiles of LMS and UL with 1p-- suggests the possibility of a common pathogenetic mechanism.