Characteristic chromosome abnormalities, including rearrangements of 6p, del(7q), +12, and t(12;14), in 44 uterine leiomyomas

Characterization of m6A Modifiers and RNA Modifications in Uterine Fibroids

Uterine leiomyoma or fibroids are prevalent noncancerous tumors of the uterine muscle layer, yet their origin and development remain poorly understood. We analyzed RNA expression profiles of 15 epigenetic mediators in uterine fibroids compared to myometrium using publicly available RNA sequencing (RNA-seq) data. To validate our findings, we performed RT-qPCR on a separate cohort of uterine fibroids targeting these modifiers confirming our RNA-seq data. We then examined protein profiles of key N6-methyladenosine (m6A) modifiers in fibroids and their matched myometrium, showing no significant differences in concordance with our RNA expression profiles. To determine RNA modification abundance, mRNA and small RNA from fibroids and matched myometrium were analyzed by ultra-high performance liquid chromatography-mass spectrometry identifying prevalent m6A and 11 other known modifiers. However, no aberrant expression in fibroids was detected. We then mined a previously published dataset and identified differential expression of m6A modifiers that were specific to fibroid genetic subtype. Our analysis also identified m6A consensus motifs on genes previously identified to be dysregulated in uterine fibroids. Overall, using state-of-the-art mass spectrometry, RNA expression, and protein profiles, we characterized and identified differentially expressed m6A modifiers in relation to driver mutations. Despite the use of several different approaches, we identified limited differential expression of RNA modifiers and associated modifications in uterine fibroids. However, considering the highly heterogenous genomic and cellular nature of fibroids, and the possible contribution of single molecule m6A modifications to fibroid pathology, there is a need for greater in-depth characterization of m6A marks and modifiers in a larger and diverse patient cohort.

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.

Characterization of m6A modifiers and RNA modifications in uterine fibroids

Uterine leiomyoma or fibroids are the most common prevalent noncancerous tumors of the uterine muscle layer. Common symptoms associated with fibroids include pelvic pain, heavy menstrual bleeding, anemia, and pelvic pressure. These tumors are a leading cause of gynecological care but lack long-term therapy as the origin and development of fibroids are not well understood. Several next-generation sequencing technologies have been performed to identify the underlying genetic and epigenetic basis of fibroids. However, there remains a systemic gap in our understanding of molecular and biological process that define uterine fibroids. Recent epitranscriptomics studies have unraveled RNA modifications that are associated with all forms of RNA and are thought to influence both normal physiological functions and the progression of diseases. We quantified RNA expression profiles by analyzing publicly available RNA-seq data for 15 known epigenetic mediators to identify their expression profile in uterine fibroids compared to myometrium. To validate our findings, we performed RT-qPCR on a separate cohort of uterine fibroids targeting these modifiers confirming our RNA-seq data. We then examined protein profiles of key m6A modifiers in fibroids and their matched myometrium. In concordance with our RNA expression profiles, no significant differences were observed in these proteins in uterine fibroids compared to myometrium. To determine abundance of RNA modifications, mRNA and small RNA from fibroids and matched myometrium were analyzed by UHPLC MS/MS. In addition to the prevalent N6-methyladenosine (m6A), we identified 11 other known modifiers but did not identify any aberrant expression in fibroids. We then mined a previously published dataset and identified differential expression of m6A modifiers that were specific to fibroid genetic sub-type. Our analysis also identified m6A consensus motifs on genes previously identified to be dysregulated in uterine fibroids. Overall, using state-of-the-art mass spectrometry, RNA expression and protein profiles, we characterized and identified differentially expressed m6A modifiers in relation to driver mutations. Despite the use of several different approaches, we identified limited differential expression of RNA modifiers and associated modifications in uterine fibroids. However, considering the highly heterogenous genomic and cellular nature of fibroids, and the possible contribution of single molecule m6A modifications to fibroid pathology, there is a need for greater in-depth characterization of m6A marks and modifiers in a larger and varied patient cohort.

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.

ZNF76 predicts prognosis and response to platinum chemotherapy in human ovarian cancer

Ovarian cancer (OV) is the most lethal gynecologic malignancy. One major reason of the high mortality of the disease is due to platinum-based chemotherapy resistance. Increasing evidence reveal the important biological functions and clinical significance of zinc finger proteins (ZNFs) in OV. In the present study, the relationship between the zinc finger protein 76 (ZNF76) and clinical outcome and platinum resistance in patients with OV was explored. We further analyzed ZNF76 expression via multiple gene expression databases and identified its functional networks using cBioPortal. RT-qPCR and IHC assay shown that the ZNF76 mRNA and protein expression were significantly lower in OV tumor than that in normal ovary tissues. A strong relationship between ZNF76 expression and platinum resistance was determined in patients with OV. The low expression of ZNF76 was associated with worse survival in OV. Multivariable analysis showed that the low expression of ZNF76 was an independent factor predicting poor outcome in OV. The prognosis value of ZNF76 in pan-cancer was validated from multiple cohorts using the PrognoScan database and GEPIA 2. A gene-clinical nomogram was constructed by multivariate cox regression analysis, combined with clinical characterization and ZNF76 expression in TCGA. Functional network analysis suggested that ZNF76 was involved in several biology progressions which associated with OV. Ten hub genes (CDC5L, DHX16, SNRPC, LSM2, CUL7, PFDN6, VARS, HSD17B8, PPIL1, and RGL2) were identified as positively associated with the expression of ZNF76 in OV. In conclusion, ZNF76 may serve as a promising prognostic-related biomarker and predict the response to platinum in OV patients.

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.

Integrated Epigenome, Exome, and Transcriptome Analyses Reveal Molecular Subtypes and Homeotic Transformation in Uterine Fibroids

Uterine fibroids are benign myometrial smooth muscle tumors of unknown etiology that, when symptomatic, are the most common indication for hysterectomy in the United States. Unsupervised clustering of results from DNA methylation analyses segregates normal myometrium from fibroids and further segregates the fibroids into subtypes characterized by MED12 mutation or activation of either HMGA2 or HMGA1 expression. Upregulation of HMGA2 expression does not always appear to be dependent on translocation but is associated with hypomethylation in the HMGA2 gene body. HOXA13 expression is upregulated in fibroids and correlates with expression of typical uterine fibroid genes. Significant overlap of differentially expressed genes is observed between cervical stroma and uterine fibroids compared with normal myometrium. These analyses show a possible role of DNA methylation in fibroid biology and suggest that homeotic transformation of myometrial cells to a more cervical stroma phenotype could be an important mechanism for etiology of the disease.

Haplotypes of CYP1B1 and CCDC57 genes in an Afro-Caribbean female population with uterine leiomyoma

Uterine leiomyomas (UL) are prevalent benign tumors, especially among women of African ancestry. The disease also has genetic liability and is influenced by risk factors such as hormones and obesity. This study investigates the haplotypes of the Cytochrome P450 1B1 gene (CYP1B1) related to hormones and coiled-coil domain containing 57 gene (CCDC57) related to obesity in Afro-Caribbean females. Each haplotype was constructed from unphased sequence data using PHASE v.2.1 software and Haploview v.4.2 was used for linkage disequilibrium (LD) studies. There were contrasting LD observed among the single nucleotide polymorphisms of CYP1B1 and CCDC5. Accordingly, the GTA haplotype of CYP1B1 was significantly associated with UL risk (P = 0.02) while there was no association between CCDC57 haplotypes and UL (P = 0.2) for the ATG haplotype. As such, our findings suggest that the Asp449Asp polymorphism and GTA haplotype of CYP1B1 may contribute to UL susceptibility in women of Afro-Caribbean ancestry in this population.

Recent Developments in Surgical Pathology of the Uterine Corpus

There have been several updates recently on the classification of uterine tumors. Endometrial carcinomas have traditionally been divided into 2 types, but some are difficult to classify and do not fit readily into either of the currently recognized categories. The Cancer Genome Atlas Research Network has recently defined 4 new categories of endometrial cancer on the basis of mutational spectra, copy number alteration, and microsatellite instability, which might provide independent prognostic information beyond established risk factors. The Society of Gynecologic Oncology, moreover, now recommends systematic screening of every patient with endometrial cancer for Lynch syndrome. The new definition of high-grade endometrial stromal sarcoma disregards the number of mitotic figures as a primary diagnostic criterion and instead specifies moderate atypia still resembling stromal origin but lacking the pleomorphism of undifferentiated uterine sarcoma; these tumors also harbor a JAZF1-SUZ12 gene rearrangement. Mitotic count, atypia, and coagulative necrosis are the main histologic criteria that define leiomyosarcoma. Determining the type of necrosis can be very challenging in patients receiving various treatment modalities for symptomatic fibroids before myomectomy, since key histologic features of ischemic-type necrosis are often absent. Ancillary stains including p16, p53, MIB-1, trichrome, and reticulin may be helpful in tumors harboring necrosis that is difficult to classify. Minimally invasive gynecologic surgeries have introduced histologic artifacts that complicate the diagnosis. It is essential to recognize these as procedure-related artifacts to avoid upstaging tumors and triggering unnecessary adjuvant treatment.

An unusual karyotype in leiomyoma: Case report and literature review

Vascular leiomyoma are uncommon, clinically benign smooth muscle tumors. Here we report a case of an otherwise typical leiomyoma with unusual cytogenetic changes including t(1;10). Reports from the existing literature suggest that approximately 40-50% of leiomyomas contain nonrandom chromosomal abnormalities of which a subset is tumor specific. t(12;14)(q15;q24) is one of the most common translocations, which occur in approximately 20% of karyotypes. Additional aberrations include del(7)(q22-q32), trisomy 12, and 6p21 rearrangements. Other recurrent abnormalities include monosomy 22, monosomy 10, del(10q), and structural rearrangements of chromosome 3.

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

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

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.

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 Genetics of Infertility: Current Status of the Field

Infertility is a relatively common health condition, affecting nearly 7% of all couples. Clinically, it is a highly heterogeneous pathology with a complex etiology that includes environmental and genetic factors. It has been estimated that nearly 50% of infertility cases are due to genetic defects. Hundreds of studies with animal knockout models convincingly showed infertility to be caused by gene defects, single or multiple. However, despite enormous efforts, progress in translating basic research findings into clinical studies has been challenging. The genetic causes remain unexplained for the vast majority of male or female infertility patients. A particular difficulty is the huge number of candidate genes to be studied; there are more than 2,300 genes expressed in the testis alone, and hundreds of those genes influence reproductive function in humans and could contribute to male infertility. At present, there are only a handful of genes or genetic defects that have been shown to cause, or to be strongly associated with, primary infertility. Yet, with completion of the human genome and progress in personalized medicine, the situation is rapidly changing. Indeed, there are 10-15 new gene tests, on average, being added to the clinical genetic testing list annually.

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.).

The potential of carboxypeptidase M as a therapeutic target in cancer

INTRODUCTION

In the recent literature, carboxypeptidase M (CPM) emerged as a potential cancer biomarker. CPM modulates receptor signaling of kinins, anaphylatoxins, and chemokines. These CPM substrates affect proliferation, angiogenesis, and apoptosis of cancer cells. What is the evidence that CPM is a drug target for cancer therapy?

AREAS COVERED

The literature was searched using PubMed with the search terms "carboxypeptidase M" and/or "chromosome 12q13-15" eventually combined with general terms related to cancer. Information was retrieved from the GEO database and material of gene expression and proteomic studies.

EXPERT OPINION

CPM is a part of the molecular signature of many cancers. There is good evidence that it is useful for the discrimination and stratification of cancer types, possibly in combination with other markers such as EGFR and MDM2. Whether it is also a drug target remains to be determined. Lung, kidney, brain, and the reproductive system contain relatively high levels of CPM, but its functions in those tissues are largely unknown. CPM is expressed on tumor-associated macrophages. To facilitate the investigation of CPM in tumor-associated inflammation and in the other aspects of tumor biology, it is necessary to develop potent and selective CPM inhibitors.

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.

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.

Value and limitation of immunohistochemical expression of HMGA2 in mesenchymal tumors: about a series of 1052 cases

The high mobility group A (HMGA2) gene encodes a protein that alters chromatin structure and regulates the transcription of many genes; it is implicated in both benign and malignant neoplasias, but its rearrangements are a feature of development of several mesenchymal tumors. Given its implication in these tumors and particularly adipocytic tumors, and the availability of antibodies usable on paraffin-embedded tissues, we evaluated the immunohistochemical expression of this gene in a series of 1052 mesenchymal tumors. The objective was to define the value and limitations of HMGA2 immunohistochemical expression for histotyping, and compare with molecular data reported in the literature. We thus analyzed 880 cases on tissue microarray and 182 cases on whole sections (211 adipocytic tumors, 628 sarcomas, 213 benign mesenchymal tumors, and 10 normal adipose tissues). A nuclear immunostaining was detected in 86% of conventional and intramuscular lipomas, in 86% of well-differentiated liposarcomas and in 67% of dedifferentiated liposarcomas, as opposed to 16% of other benign adipose tumors and to 15% of non-well-differentiated liposarcoma/dedifferentiated liposarcoma sarcomas. Among benign mesenchymal tumors and lesions, it was detected in 90% of nodular fasciitis and in 88% of benign fibrous histiocytomas with respective specificities of 85 and 100%, and in 90% of aggressive angiomyxoma, contrary to other vulvovaginal tumor types, which expressed HMGA2 only rarely. The normal adipose tissue was always negative for HMGA2. Although not specific, immunohistochemical detection of the HMGA2 protein is helpful for the distinction of normal adipose tissue from well-differentiated lesions, particularly on biopsy or on re-excision. It is less sensitive than MDM2/CDK4 for dedifferentiated liposarcomas diagnosis, but it appears more specific to distinguish dedifferentiated liposarcomas from other poorly differentiated sarcomas. Finally, and may be more importantly, HMGA2 is useful for the diagnosis of benign fibrous histiocytoma, nodular fasciitis and vulvovaginal benign mesenchymal tumors.

The effect of the readthrough acetylcholinesterase variant (AChE-R) on uterine muscle and leiomyomas

Acetylcholine signaling and acetylcholinesterase (AChE) function(s) are pivotal elements in muscle development. The effects of the stimulus-dependent readthrough AChE variant, AChE-R, on leiomyomas and normal myometrium proliferation were assessed in vivo and in vitro. Histological preparations and cell cultures therefrom were obtained during hysterectomies or myomectomies and included both the leiomyoma sample and the adjacent normal uterine muscle as control. In situ hybridization procedures were performed using AChE cRNA probes complementary to the human AChE-R transcript. Antibodies against the AChE-R variant served for immunohistochemical staining. To determine the biological function of AChE-R on the uterine muscle cell cultures, we used a synthetic peptide representing the potentially cleavable morphogenically active C-terminus of AChE-R (ARP). Cell proliferation was assessed using the incorporation of 5'-bromo-2-deoxyuridine (BrDU). Leiomyomas expressed an excess of AChE-R mRNA and the AChE-R protein compared with the normal myometrium. Cell cultures originating from leiomyomas proliferated significantly faster than cultures from the adjacent myometrium (P = 0.027 at BrDU incorporation). Addition of ARP (2-200 nM) caused a dose-dependent decrease in the proliferation of cell cultures from both leiomyomas and the myometrium. The effect on the myometrium reached statistical significance (at 20 and 200 nM, P = 0.02), whereas the variability of the rapidly proliferating primary cultures was high and precluded statistical significance in the leiomyoma cultures. AChE-R is involved in the proliferation of the myometrium. The inhibitory effect of ARP on the myometrium may suggest a future therapeutic role of ARP.

Characterization of HKE2: an ancient antigen encoded in the major histocompatibility complex

Genes at the centromeric end of the human leukocyte antigen region influence adaptive autoimmune diseases and cancer. In this study, we characterized protein expression of HKE2, a gene located in the centromeric portion of the class II region of the major histocompatibility complex encoding subunit 6 of prefoldin. Immunohistochemical analysis using an anti-HKE2 antibody indicated that HKE2 protein expression is dramatically upregulated as a consequence of activation. In a tissue microarray and in several tumors, HKE2 was overexpressed in certain cancers compared with normal counterparts. The localization of the HKE2 gene to the class II region, its cytoplasmic expression and putative protein-binding domain suggest that HKE2 may function in adaptive immunity and cancer.

Definition of a minimal region of deletion of chromosome 7 in uterine leiomyomas by tiling-path microarray CGH and mutation analysis of known genes in this region

Somatic interstitial deletions of chromosome segment 7q22-q31 in uterine leiomyomas are a frequent event, thought to be indicative of a tumor suppressor gene in the region. Previous LOH and CGH studies have refined this region to 7q22.3-q31, although the target gene has not been identified. Here, we have used tiling-path resolution microarray CGH to further refine the region and to identify homozygous deletions in fibroids. Furthermore, we have screened all manually annotated genes in the region for mutations. We have refined the minimum deleted region at 7q22.3-q31 to 2.79 Mbp and identified a second region of deletion at 7q34. However, we identified no pathogenic coding variation.

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.

Acetylation and alternative splicing regulate ZNF76-mediated transcription

We previously showed that ZNF76 is a general transcription repressor targeting TATA-binding protein (TBP), through a process regulated by sumoylation [G. Zheng, Y.C. Yang, ZNF76, a novel transcriptional repressor targeting TATA-binding protein, is modulated by sumoylation, J. Biol. Chem. 279 (2004) 42410-42421]. In this study, two additional regulatory mechanisms for ZNF76 were identified. ZNF76 is acetylated by p300 and deacetylated by HDAC1, and acetylation of ZNF76 leads to its loss of sumoylation and attenuation of TBP interaction. Consistent with their physical antagonism, acetylation, and sumoylation play opposite roles in regulating the transactivation of ZNF76. Besides acetylation and sumoylation, ZNF76 is also regulated through mRNA splicing: two isoforms of ZNF76 have different abilities of interacting with TBP. Our study shows that ZNF76, a TBP-interacting transcriptional modulator, is regulated by both lysine modifications and alternative splicing.

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.

ZNF76, a Novel Transcriptional Repressor Targeting TATA-binding Protein, Is Modulated by Sumoylation

Direct interaction of positive and negative regulators with the general transcription machinery modulates transcription. The TATA-binding protein (TBP) is one target for transcriptional regulators. In this study, we identified ZNF76 as a novel transcriptional repressor that targets TBP. ZNF76 interacts with TBP through both its N and C termini, and both regions are required for ZNF76 to exert its inhibitory function on p53-mediated transactivation. The inhibitory effect of ZNF76 on p53 activity was demonstrated by reporter assays and endogenous target gene expression. We mapped the TBP-interacting region in the C terminus of ZNF76 to a glutamic acid-rich domain, which acts in a dominant negative manner to enhance p53-mediated transactivation in reporter assays. Mutagenesis study for ZNF76 suggests a correlation between interaction with TBP and effect on p53-mediated transactivation, supporting the conclusion that ZNF76 targets TBP for transcriptional repression. Chromatin immunoprecipitation experiments suggest that ZNF76 prevents TBP from occupying the endogenous p21 promoter. ZNF76 is sumoylated by PIAS1 at lysine 411, which is in the minimal TBP-interacting region. Overexpression of PIAS1 and SUMO-1 abolishes the interaction between ZNF76 and TBP and partially relieves the repressive effect of ZNF76. These results suggest that ZNF76 functions as a transcriptional repressor through its interaction with TBP and that sumoylation modulates its transcriptional repression activity.

Differential gene expression in uterine leiomyoma

Uterine leiomyomas are the most common tumor of the genitourinary system in women and are a major cause of morbidity. The molecular causes of the disease remain unclear. In this study, we examined gene expression in leiomyomas and normal myometrium. RNA was prepared and gene expression determined with the use of Affymetrix GeneChip U_95 arrays containing approximately 12,000 known genes and 48,000 expression sequence tags. Several genes were found to be differentially expressed in these two sample sets, and these genes were analyzed for their expression in a variety of other normal and diseased tissues. Four genes--doublecortin, calpain 6, interleukin-17B, and proteolipid protein 1--were found to be overexpressed in leiomyomas compared with normal myometrium and eighteen other tissues. Sets of genes were identified whose expression could be used to cluster samples with leiomyomas or normal myometrium with the use of Eisen Cluster software. We conclude that differences in gene expression can be detected between leiomyomas and normal myometrium and that these changes in gene expression may yield clues to the pathophysiology of this common tumor.

Identification of up-regulated genes in human uterine leiomyoma by suppression subtractive hybridization

In searching for differentially expressed genes in human uterine leiomyomas (ULs), suppression subtractive hybridization was used to construct an UL up-regulated library, which turned out to represent 88 genes. After two rounds of screening by reverse Northern analysis, twenty genes were proved to be up-regulated, including seventeen known genes and three genes with unknown function. All these genes were firstly associated with UL. Three genes with notable difference were selected for Northern confirmation. Our results proved the authenticity of the twenty genes. One gene named Phospholipase A2 (PLA2) showed up-regulation in 4/6 of the patients and investigation of tissue distribution indicated that it had obvious expression in prostate, testis, liver, heart and skeletal muscle.

The HMG I proteins: dynamic roles in gene activation, development, and tumorigenesis

The high mobility group I, Y, and I-C proteins are low-molecular-weight, nonhistone chromosomal proteins that play a general role modulating gene expression during development and the immune response. Consistent with their role in early development, all three proteins are expressed at high levels during embryogenesis, and their expression is markedly diminished in differentiated cells. Exceptions to the general repression of these genes in adult tissues involve (1) A burst of synthesis of the HMG I protein during the immune response (during lymphocyte activation and preceding cytokine/adhesion molecule gene expression), (2) A constitutive expression of the HMG I and Y proteins in photoreceptor cells, and (3) Derepression of HMG I, Y, and often I-C expression in neoplastic cells. Work from several laboratories has now uncovered how these proteins participate in gene activation: (1) By altering the chromatin structure around an inducible gene-and thus influencing accessibility of the locus to regulatory proteins-(2) By facilitating the loading of transcription factors onto the promoters, and (3) By bridging adjacent transcription factors on a promoter via protein/protein interactions. Despite the similar structures and biochemical properties of the three proteins, the work has also provided clues to a division of labor between these proteins. HMG I and Y have demonstrable roles in enhanceosome formation, whereas HMG I-C has a specific role in adipogenesis. C-terminal truncations of HMG I-C and wild-type HMG Y appear to function in a manner analogous to oncogenes, as assessed by cellular transforation assays and transgenic mice. Future work should clearly define the similarities and differences in the biological roles of the three proteins, and should evolve to include attempts at pharmaceutical intervention in disease, based upon structural information concerning HMG I interactions with DNA and with regulatory proteins.

Differential binding of an SRF/NK-2/MEF2 transcription factor complex in normal versus neoplastic smooth muscle tissues

The malignant potential of smooth muscle tumors correlates strongly with the disappearance of gamma-smooth muscle isoactin, a lineage-specific marker of smooth muscle development. In this paper, we identify a 36-base pair regulatory motif containing an AT-rich domain, CArG box, and a non-canonical NK-2 homeodomain-binding site that has the capacity to regulate smooth muscle-specific gene expression in cultured intestinal smooth muscle cells. Serum-response factor associates with an NK-2 transcription factor via protein-protein interactions and binds to the core CArG box element. Our studies suggest that the NK-2 transcription factor that associates with serum-response factor during smooth muscle differentiation is Nkx2-3. Myocyte-specific enhancer factor 2 binding to this regulatory complex was also observed but limited to uterine smooth muscle tissues. Smooth muscle neoplasms displayed altered transcription factor binding when compared with normal myometrium. Differential nuclear accessibility of serum-response factor protein during smooth muscle differentiation and neoplastic transformation was also observed. Thus, we have identified a unique regulatory complex whose differential binding properties and nuclear accessibility are associated with modulating gamma-smooth muscle isoactin-specific gene expression in both normal and neoplastic tissues.

Multiple leiomyomas of the esophagus, lung, and uterus in multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disorder characterized by multiple parathyroid, pancreatic, duodenal, and pituitary neuroendocrine tumors. Nonendocrine mesenchymal tumors, such as lipomas, collagenomas, and angiofibromas have also been reported. MEN1-associated neuroendocrine and some mesenchymal tumors have documented MEN1 gene alterations on chromosome 11q13. To test whether the MEN1 gene is involved in the pathogenesis of multiple smooth muscle tumors, we examined the 11q13 loss of heterozygosity (LOH) and clonality patterns in 15 leiomyomata of the esophagus, lung, and uterus from five patients with MEN1. Forty sporadic uterine leiomyomata were also studied for 11q13 LOH. LOH analysis was performed using four polymorphic DNA markers at the MEN1 gene locus; D11S480, PYGM, D11S449, and INT-2. 11q13 LOH was detected in 10 of 12 (83%) MEN1-associated esophageal and uterine smooth muscle tumors. In contrast, LOH at the MEN1 gene locus was demonstrated only in 2 of 40 (5%) sporadic uterine tumors. LOH at 11q13 was not documented in three lung smooth muscle tumors from a single patient with MEN1. Ten tumors from two female patients were additionally assessed for clonality by X-chromosome inactivation analysis. The results demonstrated different clonality patterns in multiple tumors in the same organ in each individual patient. The data indicate that leiomyomata of the esophagus and uterus in MEN1 patients arise as independent clones, develop through MEN1 gene alterations, and are an integral part of MEN1. However, the MEN1 gene is not a significant contributor to the tumorigenesis of sporadic uterine leiomyomata.

Molecular cytogenetic analysis of uterine leiomyoma and leiomyosarcoma by comparative genomic hybridization

Uterine leiomyomata are among the most common of human neoplasms and are associated with abnormal uterine bleeding, infertility, and abdominal pain. Uterine leiomyosarcomata are presumed to be the malignant counterpart to uterine leiomyomata and are very rare. Transformation of uterine leiomyoma (ULM) into uterine leiomyosarcoma (ULMS) is yet to be conclusively confirmed, and each type of tumor may represent a distinct genetic entity. We used comparative genomic hybridization (CGH) to evaluate DNA sequence copy-number changes in 12 specimens of ULM and 8 of ULMS. CGH analysis of ULM demonstrated chromosomal imbalances in 8 of 12 (66. 7%) specimens. The most frequent ULM gains were observed at 9q34 (a novel finding) and on chromosome 19. Other ULM imbalances included gains and losses of chromosome 1p, losses on 7q, and gains on 12q. All ULMS specimens demonstrated chromosomal aberrations. Chromosome 1 imbalances were very prominent. The most frequent losses were detected on 14q and 22q. Losses on 14q are rarely seen in other types of leiomyo-sarcoma and may be a distinctive feature of ULMS. Gains on chromosomes 8, 17, and X were observed in half the cases and were accompanied by high-level amplification. Other chromosome arms overrepresented included 12q and 19p. The absence of specific anomalies common to all ULM and ULMS argues against their being benign-malignant counterparts.

Frequent loss of heterozygosity for chromosome 10 in uterine leiomyosarcoma in contrast to leiomyoma

Distinction of malignant uterine leiomyosarcomas from benign leiomyomas by morphological criteria is not always possible. Leiomyosarcomas typically have complex cytogenetic abnormalities; in contrast, leiomyomas have simple or no cytogenetic abnormalities. To understand better the biological distinction(s) between these tumors, we analyzed two other potential markers of genomic instability, loss of heterozygosity (LOH) and microsatellite instability. We examined archival materials from 16 leiomyosarcomas and 13 benign leiomyomas by polymerase chain reaction for 26 microsatellite polymorphisms. Markers were selected based on previous reports of cytogenetic or molecular genetic abnormalities in leiomyosarcomas or leiomyomas and surveyed chromosomes 7, 9, 10, 11, 12, 14, 15, 16, 18, 21, and X. LOH for markers on chromosomes 15, 18, 21, and X was infrequent in leiomyosarcomas (1 of 6 tumors for each chromosome) and not observed for markers on chromosomes 7, 9, 11, 12, 14, or 16. Interestingly, 8 of 14 (57.2%) informative leiomyosarcomas had LOH for at least one marker on chromosome 10 and involved both chromosomal arms in 45.5% (5 of 11). In contrast to leiomyosarcomas, LOH for chromosome 10 was not found in 13 benign leiomyomas. Microsatellite instability was found infrequently in leiomyosarcomas and not detected in leiomyoma. Clinicopathological features (eg, atypia, necrosis, and clinical outcome) did not appear to correlate with LOH for chromosome 10. In contrast to other chromosomes studied, LOH on chromosome 10 was frequent in leiomyosarcomas and absent in benign leiomyomas.

Deletion of HMG17 in uterine leiomyomas with ring chromosome 1

Uterine leiomyomas are characterized by several subgroups with characteristic chromosomal aberrations, mainly 12q14-15, 6p21, or interstitial deletions of chromosomes 3 and 7. For the first two subgroups, aberrations of the HMGIC and HMGIY genes have been described and are held responsible for tumor initiation. For other subgroups no molecular findings have been described as of yet. We focus here on a smaller subgroup of uterine leiomyomas with a ring chromosome 1 either as the only karyotypic deviation or occurring along with other abnormalities. In the p-arm of chromosome 1 HMG17, another member of the high-mobility group of proteins has been localized to the short arm of chromosome 1 (1p35) with two PAC clones on metaphase spreads of a uterine leiomyoma ring(1). Hybridization signals for these probes were not detected within the ring chromosome consistent with loss or deletion of HMG17. These findings suggest that HMG17 does not play a mechanistic role in leiomyoma similar to that observed with other high-mobility proteins.

S-phase fraction related to prognosis in localised prostate cancer. No specific significance of chromosome 7 gain or deletion of 7q31.1

A flow-cytometric (FCM) and fluorescence in situ hybridization (FISH) study was performed in 153 patients with clinically localised prostate cancer (PC) to evaluate retrospectively the prognostic significance of DNA ploidy, S-phase fraction (SPF) and chromosome 7 copy number. Deletions in 7q31.1 were analysed in a subset of 26 tumours. The mean follow-up time was 6 years (range 4-16 years). Twelve cases of benign prostatic hyperplasia (BPH) were studied as a control. Chromosome 7 enumeration and deletion studies were conducted using the alpha-satellite D7Z1 probe and a cosmid probe specific for the marker D7S522 on 7q31.1. Higher SPF was associated with shorter overall survival and shorter time to local progression and metastasis. Near diploid (DNA index 1.05-1.20) cases had a lower frequency of metastases and lower Gleason scores than aneuploid cases. Increased absolute chromosome 7 copy number (centromere count) was associated with higher Gleason score, higher SPF and shorter local progression-free and prostate cancer survival. Absolute chromosome 7 copy number was concordant with FCM DNA ploidy in the majority (75%) of cases. Relative gain or loss of chromosome 7 (centromere counts compared to ploidy) was infrequent, and no correlation was found with clinical parameters. Deletions in 7q31.1 were infrequent. Our results indicate that in localised PC (i) SPF is a prognostic factor, (ii) absolute chromosome 7 copy number is concordant with the ploidy status of the tumour (relative gain or loss of chromosome 7 is infrequent and has no independent prognostic value) and (iii) the frequency of deletions in 7q31.1 is low and not correlated with clinical outcome.

A sole del(15q) anomaly in post-myelodysplasia acute myeloid leukemia

We report the second case of post-myelodysplasia acute myeloid leukemia (post-MDS AML) with a sole chromosome change del(15q). This anomaly is rarely seen. To our knowledge, only seven cases so far have been reported in human neoplasias, including one case each of acute myeloid leukemia (AML), acute lymphoid leukemia, post myelodysplasia AML, myelodysplastic syndrome, myelofibrosis, macroglobulinemia, Hodgkin's lymphoma and uterine leiomyoma. This case suggests that del(15q) is related to lympho-myeloproliferative disorders. Moreover, we speculate that certain oncogene(s) located on 15q might have some role in the progression of the disease, since the del(15q) anomaly appeared only in the AML phase in this case.

Physical map of human 6p21.2-6p21.3: region flanking the centromeric end of the major histocompatibility complex

We have physically mapped and cloned a 2.5-Mb chromosomal segment flanking the centromeric end of the major histocompatibility complex (MHC). We characterized in detail 27 YACs, 144 cosmids, 51 PACs, and 5 BACs, which will facilitate the complete genomic sequencing of this region of chromosome 6. The contig contains the genes encoding CSBP, p21, HSU09564 serine kinase, ZNF76, TCP-11, RPS10, HMGI(Y), BAK, and the human homolog of Tctex-7 (HSET). The GLO1 gene was mapped further centromeric in the 6p21.2-6p21.1 region toward TCTE-1. The gene order of the GLO1-HMGI(Y) segment in respect to the centromere is similar to the gene order in the mouse t-chromosome distal inversion, indicating that there is conservation in gene content but not gene order between humans and mice in this region. The close linkage of the BAK and CSBP genes to the MHC is of interest because of their possible involvement in autoimmune disease.

Cloning of a breakpoint cluster region on chromosome 14 in uterine leiomyoma

A recurrent reciprocal chromosomal translocation, t(12;14)(q15;q24) is frequently observed in uterine leiomyoma. Chromosome 12 breakpoints have been shown to occur in a region of approximately 150 kb that contains the gene for a high mobility group protein (HMGI-C). The breakpoint region on chromosome 14 has not been precisely defined. We have generated a contig of overlapping yeast artificial chromosome (YAC) clones approximately 3 Mb in size. Fluorescence in situ hybridization (FISH) analysis showed that this contig spanned the t(12;14) breakpoints in three uterine leiomyomas and that the breakpoints in these tumors occurred within a 1 Mb region. A 30 kb cosmid spanning one of the breakpoints was isolated to set the stage for identifying regions on chromosome 14 that may cause this region to be a preferential site for chromosomal translocation.

TAPASIN, DAXX, RGL2, HKE2 and four new genes (BING 1, 3 to 5) form a dense cluster at the centromeric end of the MHC

TAPASIN, a gene recently shown to be required for antigen presentation through MHC class I molecules, is located 180 kbp centromeric of HLA-DP in a region linked to several diseases, and associated with altered developmental phenotypes in the mouse. We present the genomic analysis of a 70 kbp gene-dense segment flanking the TAPASIN locus, including sequence, structure and preliminary characterisation of seven additional genes. BING1 is a Zn finger gene containing a POZ motif. BING3 is similar to myosin regulatory light chain. BING4 shows homologies only to hypothetical yeast and Caenorhabditis elegans proteins. BING5 is found within an intron of BING4 on the complementary strand, and encodes a molecule with no homologies to database proteins. Another three genes were identified whose full sequence was not previously known; namely, RGL2, DAXX (BING2) and HKE2. RGL2 encodes an effector of Ras, homologous to the mouse RalGDS protein, Rlf. DAXX encodes an effector of Fas that stimulates apoptosis through the Jun kinase (JNK) pathway. The location of DAXX is of interest given the linkage of autoimmune disease to the MHC and to apoptosis.

Proliferation and the monoclonal origins of atherosclerotic lesions

Benditt's observation of the monoclonal origin of the atherosclerotic lesion has been controversial because it appeared to conflict with conventional wisdom. A new method based on a polymerase chain reaction amplification of the DNA of an X-inactivated gene from microdissected tissue confirms that Benditt was correct. However, this monoclonal expansion can also be found in nonatherosclerotic intima and media. These new data suggest that plaque clonality may represent expansion of preexisting patches of cells arising during development of the media. This developmental view does not conflict with other recent evidence that plaque expansion is associated with mutation or viral events. However, if plaques arise from patches, then early developmental mechanisms may be critical to the later evolution of the lesions.

Frequency and implications of chromosome 8 and 12 gains in Ewing sarcoma

Ewing sarcoma (ES) is the second most common primary malignant tumor of bone in children and young adolescents. Most ES contain a pathognomonic translocation t(11;22)(q24;q12) that is likely a pivotal event in the tumorigenesis of these neoplasms. Many ES also contain nonrandom, numerical chromosomal aberrations, the most common of which are trisomies 8 and 12. In this study we evaluated the hypothesis that these trisomies might occur during neoplastic progression and might be associated with differences in biologic behavior. We tested this hypothesis using a combined cytogenetic and dual color fluorescence in situ hybridization approach to determine chromosome 8 and 12 copy number in 52 ES. Relative gains, primarily trisomies, of chromosomes 8 and 12 were found in 24 (46%) and 17 (33%) cases, respectively. Trisomy 8 and trisomy 12 were independent events acquired in a flexible order during ES genetic progression. Our preliminary findings also suggest a higher frequency of trisomies 8 and 12 in relapses than in primary tumors. Prospective studies will be required to determine whether either trisomy is prognostic in newly-diagnosed ES.

HMGIC expressed in a uterine leiomyoma with a deletion of the long arm of chromosome 7 along with a 12q14-15 rearrangement but not in tumors showing del(7) as the sole cytogenetic abnormality

Cytogenetic studies on uterine leiomyomas have shown that more than 60% of these tumors possess a normal karyotype and that 30% have clonal chromosomal aberrations. The most frequent changes are aberrations involving 12q14-15 and show rearrangements of the long arm of chromosome 7. Recently, we were able to demonstrate that in a variety of mesenchymal tumors showing 12q14-15 aberrations the HMGIC gene is rearranged thus playing a role in tumorigenesis. Here we report the results of HMGIC expression studies by RT-PCR of five uterine leiomyomas with different karyotypes. The RT-PCR studies were performed on two primary tumors showing a 12q14-15 aberration, one of which with an additional del(7) and three tumors with del(7) as the sole aberration. The tumor with the 12q14-15 aberration as the sole alteration and the leiomyoma with 12q14-15 rearrangement plus deletion of the long arm of chromosome 7 were shown to express HMGIC. In contrast, in all three tumors with the del(7) as the sole aberration no expression of HMGIC was noted.

Two discrete regions of deletion at 7q in uterine leiomyomas

This study further defines the region of consistent deletion of chromosome 7 in uterine leiomyomas. We have examined 74 leiomyomas for allelic loss of markers spanning the 7q22 region defined by markers D7S518 and D7S471. Forty tumors with cytogenetically defined 7q deletions, twenty-nine tumors without cytogenetically visible 7q deletions, and five tumors with no cytogenetic information were examined for allelic loss of D7S518, D7S666, D7S515, D7S658, D7S496, D7S692, and D7S471. Loss of heterozygosity for one or more of these loci was observed in twenty-eight leiomyomas with cytogenetically defined 7q deletions and in three leiomyomas with a normal karyotype. Allelic loss of D7S666 was common and was observed in all twenty-three informative tumors with 7q deletions and in two tumors with normal karyotypes. This study indicates the presence of a tumor suppressor gene in close proximity to the D7S666 locus. Eight tumors followed an unusual pattern of allelic loss. These tumors showed retention of heterozygosity for at least one locus flanked by deleted loci. These results suggest the possibility that two discrete regions of deletion at 7q22 are involved in the development of a subset of leiomyomas.

Structural abnormalities of chromosome 7q in chronic lymphoproliferative disorders

Structural abnormalities of 7q are common in myeloid malignancies but rarely reported in chronic lymphoproliferative disorders. 7q abnormalities were found in 29 of 796 patients (3.6%) with chronic lymphoid malignancies. The most common association was found in splenic lymphoma with villous lymphocytes (SLVL) in which 8 of 31 cases (26%) has one or more abnormalities of 7q. The most common abnormalities were deletions involving 7q32 and deletions or translocation of 7q22. There was no correlation between the type of lymphoid disorder or clinical course and specific structural abnormalities. We postulate that genes important in the pathogenesis of SLVL may reside on 7q22 and/or 7q32.