Different karyotypic abnormalities, t(1;6) and del(7), in two uterine leiomyomas from the same patient

Cytogenetic studies of two uterine leiomyomas from the same patient revealed different karyotypic changes. Both tumors showed only a single chromosome abnormality; one had t(1;6)(q23;p21) and the other del(7)(q21.2q31.2). These findings support the view that multiple leiomyomas of the uterus arise independently.     

Parallel karyotypic evolution and tumor progression in uterine leiomyoma

Cytogenetic evidence of clonal evolution was detected in five uterine leiomyomas. In two tumors, two clones were found, the third tumor had four, the fourth had nine, and the fifth had 12 clones. The first tumor had trisomy 12 as the primary anomaly and a sideline that also contained a del(7)(q21q31). Both clones of the second tumor had three structural changes in common but differed by the presence in the more advanced clone of an inv(7)(q31q34). Two cytogenetically unrelated pairs of clones were seen in the third tumor. One clone had a stemline of 46 and an r(1); a sideline had developed through duplication of this clone. The other pair had a del(7)(q21q31) in common. The last two tumors both had t(12;14)(q14-15;q23-24) as the primary abnormality. They also had a high frequency of telomeric associations that involved certain chromosome arms only. One of the secondary changes in the fourth tumor was a del(7)(q21q31); the principal secondary change in the fifth case was a ring chromosome 1 of variable size in the different clones. The analysis of these five uterine leiomyomas and the collation of the results with previously obtained data lead us to conclude that del(7)(q21q31) is secondary to t(12;14) and + 12 in this tumor type, and that ring formation involving chromosome 1 material, often with duplication of segments, is a common phenomenon during clonal evolution. The fact that the tumors were classified as cellular and had an increased mitotic rate indicates a parallel development between histologically detectable tumor progression and cytogenetically recognizable clonal evolution in uterine leiomyomas.     

Chromosome analysis of 96 uterine leiomyomas

From September 1989 to May 1990, we attempted cytogenetic analysis on 96 uterine leiomyomas removed from 64 women. Of the 90 tumors in which analysis was successful, 59 had a normal karyotype while 31 had clonal abnormalities. The most common aberration (13 tumors) was 7q-, mostly del(7)(q21.2q31.2); in two tumors with +12 and t(12;14) as the primary abnormalities, the 7q- was obviously a secondary change since it was found only in a subclone. A t(12;14)(q14-15;q23-24) was detected in two tumors, complex aberrations involving both 12q14-15 and 14q23-24 were also present in two, and rearrangements of 12q without concomitant 14q changes were seen in another two myomas. Rearrangements of 6p were present in five tumors, and trisomy 12 was found in two. More than one abnormality could be detected in 17 leiomyomas. Evidence of clonal evolution in the form of subclones was found in eight tumors, all of which were cellular and had histologically detectable mitotic activity. In addition to their clonal complexity, these myomas also frequently exhibited clonal telomeric associations (four tumors) and ring chromosome formation (three tumors; twice affecting chromosome 1). Monosomy 22 occurred as a secondary abnormality in three tumors; it, too, may reflect a preferred pathway in the karyotypic evolution of uterine leiomyomas.     

Uterine leiomyoma cytogenetics

Uterine leiomyoma--a benign smooth muscle tumor--has recently been found to contain tumor-specific chromosome aberrations. Although only normal karyotypes were detected in 50 to 80% of cytogenetically investigated tumors, 104 leiomyomas with karyotypic aberrations have already been reported. At least four cytogenetically abnormal subgroups have been identified thus far, characterized by rearrangements of 6p, del(7)(q21.2q31.2), +12, and t(12;14)(q14-15;q23-24). The remaining abnormal tumors have had various nonrecurrent anomalies. Secondary karyotypic rearrangements, sometimes including ring chromosomes, have been found in one-third and reflect clonal evolution. Occasional leiomyomas have contained multiple numerical and structural rearrangements. Though benign, these cytogenetically grossly aberrant tumors often displayed more atypical histological features than are usually seen in leiomyoma. Multiple leiomyomas have been investigated from 69 patients, with detection of chromosome anomalies in at least two separate tumors from the same uterus in ten cases. In half of these patients unrelated aberrations were found in different leiomyomas from the same uterus. On other occasions the aberrations were identical, indicating that although some uterine leiomyomas originate independently, others may develop by intra-myometrial spreading from a common neoplastic clone. Some common features are discernible between the karyotypic pictures of uterine leiomyoma and angioleiomyoma; rearrangements of 6p, 13q, and 21q have been described in both tumor types. The cytogenetic similarities so far detected between leiomyoma and the malignant muscle tumors--leiomyosarcoma and rhabdomyosarcoma--are few and may be fortuitous. The cytogenetic profiles of leiomyoma and lipoma are strikingly similar; both tumor types have nonrandom rearrangements of 12q13-15, t(12;14) in leiomyoma and t(3;12) in lipoma, as well as variant rearrangements of the same 12q segment. Both also have cytogenetic subgroups characterized by changes in 6p and ring chromosomes. Finally, karyotypic similarities exists also between leiomyoma and pleomorphic adenoma of the salivary gland, which includes a subset of tumors with anomalies of 12q13-15, and with myxoid liposarcoma, which has t(12;16)(q13;p11) as a tumor-specific rearrangement.     

Molecular and cytogenetic analysis of chromosome 7 in uterine leiomyomas

Uterine leiomyomas are benign tumors that arise clonally from smooth muscle cells of the myometrium. Cytogenetic studies of uterine leiomyomas have shown that about 40% have chromosome abnormalities and that deletion of 7q is a common finding. The observations suggest the possible location of a growth-suppressor gene within the 7q21-q22 region. Molecular genetic analysis of cytogenetically normal tumors has frequently shown somatic loss of specific tumor suppressor genes detected by loss of heterozygosity in the critical region. To test the hypothesis that chromosome region 7q21-q22 contains a growth-suppressor gene involved in the development of leiomyomas, we examined 92 leiomyomas for allelic loss of 7q markers spanning the cytogenetically defined critical region. Forty tumors with cytogenetically defined 7q deletion, 45 tumors without cytogenetically visible 7q deletion, and seven tumors with no cytogenetic information were examined for allelic loss of loci D7S489, D7S440, D7S492, D7S518, D7S471, D7S466, and D7S530. Loss of heterozygosity for one or more of these loci was observed in 23 of 40 (57.5%) of the tumors with deletion of 7q and in 2 of 45 cases without a cytogenetically visible deletion. The tumors with cytogenetic deletion of 7q, but no loss of 7q21-q22 markers, were mosaics, with only a minority of cells containing the cytogenetic deletion. The critical region of loss is defined by the markers D7S518 and D7S471, each showing loss in approximately 50% of informative cases. These markers define a 10 cM region of 7q21-q22 that is consistent with the cytogenetically defined smallest region of overlap and exclude loss of the MET oncogene locus and WNT1, the murine mammary tumor-virus integration site, from the critical region. Our results further define a region that is consistently lost in leiomyomas with cytogenetic deletion of chromosome arm 7q. This region may contain a tumor suppressor gene involved in the development of a subset of leiomyomas.     

Biallelic inactivation of fumarate hydratase (FH) occurs in nonsyndromic uterine leiomyomas but is rare in other tumors

Germline mutations in the fumarate hydratase (FH) gene at 1q43 predispose to dominantly inherited cutaneous and uterine leiomyomas, uterine leiomyosarcoma, and papillary renal cell cancer (HLRCC syndrome). To evaluate the role of FH inactivation in sporadic tumorigenesis, we analyzed a series of 299 malignant tumors representing 10 different malignant tumor types for FH mutations. Additionally, 153 uterine leiomyomas from 46 unselected individuals were subjected to and informative in loss of heterozygosity analysis at the FH locus, and the five (3.3%) tumors displaying loss of heterozygosity were subjected to FH mutation analysis. Although mutation search in the 299 malignant tumors was negative, somatic FH mutations were found in two nonsyndromic leiomyomas; a splice site change IVS4 + 3A>G, leading to deletion of exon four, and a missense mutation Ala196Thr. The occurrence of somatic mutations strongly suggests that FH is a true target of the 1q43 deletions. Although uterine leiomyomas are the most common tumors of women, specific inactivating somatic mutations contributing to the formation of nonsyndromic leiomyomas have not been reported previously. Taking into account the apparent risk of uterine leiomyosarcoma associated with FH germline mutations, the finding raises the possibility that also some nonsyndromic leiomyomas may have a genetic profile that is more prone to malignant degeneration. Our data also indicate that somatic FH mutations appear to be limited to tumor types observed in hereditary leiomyomatosis and renal cell cancer.     

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. Genes Chromosom. Cancer 19:156–160, 1997. © 1997 Wiley-Liss Inc.     

MED12 mutations occurring in benign and malignant mammalian smooth muscle tumors

Mutations of the mediator subcomplex 12 gene (MED12) recently have been described in a large group of uterine leiomyomas (UL) but only in a single malignant uterine smooth muscle tumor. To further address the occurrence of fibroid‐type MED12 mutations in smooth muscle tumors, we have analyzed samples from 34 leiomyosarcomas (LMS), 21 UL, two extrauterine leiomyomas (EL), and 10 canine genital leiomyomas for the presence of MED12 mutations of the UL‐type. Interestingly, besides UL MED12 mutations were found in one uterine LMS, one EL, and two canine vaginal leiomyomas. The results confirm the occurrence of fibroid‐type MED12 mutations in malignant uterine smooth muscle tumors thus suggesting a rare but existing leiomyoma‐LMS sequence. In addition, for the first time MED12 mutations are reported in smooth muscle tumors in a non‐primate mammalian species. © 2012 Wiley Periodicals, Inc.     

Complex chromosome rearrangements involving 12q14 in two uterine leiomyomas

Cytogenetic analysis of short-term cultures from 10 uterine leiomyomas revealed normal karyotypes in 8 and clonal complex chromosome rearrangements in 2 tumors. In both leiomyomas with clonal abnormalities, 12q14, but not 14q22-24, was involved in translocations with 1q43 in one tumor and with 12q24 in the other. Additional chromosome abnormalities were found in both cases: 1-5 rings and monosomy of chromosome 9 in case 1, and complex numerical and structural abnormalities of chromosomes 1, 6-8, 11, 13, 16, 17, and 22 in case 2. The consistent cytogenetic rearrangement of 12q14 in uterine leiomyomas, sometimes without concomitant 14q changes, indicates that a gene of critical importance for leiomyoma development may be found in this band.     

Dysregulation of HMGIC in a uterine lipoleiomyoma with a complex rearrangement including chromosomes 7, 12, and 14

Uterine lipoleiomyomas are extremely rare tumors consisting of a mixture of mature adipocytes and smooth muscle cells. Using G-banding and FISH, we characterized a complex rearrangement involving chromosomes 7, 8, 10, 11, 12, and 14 in one of these tumors. The region 14q23-24 was inserted into the long arm of the derivative chromosome 12, between the 3' end of HMGIC and 7q21-22, another region often rearranged in uterine leiomyomas. Other portions of chromosomes 12 and 14 were involved in derivative chromosomes 7, 11, 12, and 14. A chromosome 8 was involved in a three-way rearrangement including the derivative 7, a ring chromosome 10, and a small derivative chromosome 8 bearing segments of chromosomes 10 and 11. No abnormality of chromosome 5 was detected, in contrast to two previously reported cytogenetic analyses of uterine lipoleiomyoma. The consistent finding of chromosomes 12 and 14 on different derivatives indicates that the t(12;14) was a primary event. In addition, immunohistochemical studies showed that HMGI-C was aberrantly expressed in this tumor. These observations suggest that uterine lipoleiomyomas have a pathogenetic origin similar to that of typical leiomyomas. Genes Chromosomes Cancer 27:209-215, 2000.     

Genomic alterations in uterine leiomyosarcomas: potential markers for clinical diagnosis and prognosis

Genomic alterations were analyzed in 21 uterine leiomyosarcomas (ULMSs) by comparative genomic hybridization. DNA copy number changes were detected in all 21 tumors. The most frequent losses were 13q (16/21 = 76%), 10q (13/21 = 62%), 16q (8/21 = 38%), 12p (7/21 = 33%), and 2p (9/21 = 43%). The most common gains were 17p (8/21 = 38%), Xp (7/21 = 33%), and 1q (7/21 = 33%). High-copy-number gains (ratio > 1.5) were identified in Xp, 1q, and 17p. Loss of 13q was identified in both low-grade and high-grade tumors. Inactivation of a tumor suppressor gene in 13q may be an early event in the development of leiomyosarcomas. Loss of 10q, 2p, and 12p and gains of 1q as well as 17p were frequently found in high-grade tumors and recurrent tumors. Inactivation of tumor suppressor genes and activation of oncogenes in these regions may be associated with a more aggressive behavior of ULMS. Patients with only loss of 13q and without the other alterations listed above had longer survival times. Gains of Xp, 17p, and 1q and losses of 13q, 10q, 16q, 12p, and 2p have been reported in extra-uterine leiomyosarcomas. Our findings indicate that the pathogenesis of uterine leiomyosarcomas and extra-uterine leiomyosarcomas follows the same genetic pathways.     

Are uterine leiomyoma a consequence of a chronically inflammatory immune system?

The cumulative incidence of uterine leiomyoma at age 50 is ≈ 70% in White women and >80% in Black women. Although risk factor research is limited, increasing age, and being premenopausal, nulliparous or Black are risk factors for leiomyomas. Black women tend to have larger leiomyomas and be younger at diagnosis. Surprisingly little is known about the etiology or pathogenesis of uterine leiomyomas. Women with diagnosed uterine leiomyomas have higher healthcare costs - more than 2.5 times that of women without a diagnosis. In the United States, leiomyomas are the leading indication for hysterectomy. The proposed hypothesis is that leiomyomas are caused in part by a systemic immune milieu that is chronically inflammatory - one that predominates in T helper 17 (Th17) cytokines. Inflammation can be problematic if it is not well regulated. Should an inflammatory imbalance be demonstrated to be associated with leiomyoma development and growth, this would provide an avenue for development of preventative treatments (e.g., focus on anti-inflammatory pathways), which would substantially reduce the morbidity costs of these tumors and reduce a known health disparity.     

Epithelioid smooth muscle tumors of the uterus do not express CD1a: a potential immunohistochemical adjunct in their distinction from uterine perivascular epithelioid cell tumors

Uterine epithelioid smooth muscle tumors and uterine perivascular epithelioid cell tumors (PEComas) are known to display such a substantial overlap in morphologic and immunophenotypic characteristics that the existence of the latter as a distinct clinicopathologic entity at this location has been called into question. Recent research suggests that the constituent entities of the PEComa family at all anatomical locations, including lymphangioleiomyomatosis of the uterus, uniformly display immunoreactivity for CD1a. The purpose of this study is to determine the proportion of uterine epithelioid smooth muscle tumors that may similarly be CD1a-positive. Representative sections from 18 archived epithelioid smooth muscle tumors of the uterine corpus (6 epithelioid leiomyosarcomas and 12 epithelioid leiomyomas), diagnosed and classified as such based on World Health Organization criteria, were subjected to immunohistochemical stains for CD1a and HMB-45. The epithelioid component of the tissue sections evaluated ranged from 10% to 100% (mean, 70%). Two cases were composed predominantly of cells with overtly clear cytoplasm. All cases were entirely negative for CD1a. Of 18 cases, 1 (5.5%) (an epithelioid leiomyosarcoma) displayed immunoreactivity for HMB-45 in scattered lesional cells that constituted approximately 5% of the overall tumoral volume for the case. All others were HMB-45-negative. Given their rarity, future studies are required to confirm that all PEComas of the uterus are indeed uniformly positive for CD1a. However, if the latter staining pattern is confirmed, our findings herein suggest that CD1a may be a useful immunohistochemical adjunct in distinguishing uterine epithelioid smooth muscle tumors from uterine PEComas.     

High resolution mapping of consistent leiomyoma breakpoints in chromosomes 12 and 14 to 12q15 and 14q24.1

A substantial percentage of uterine leiomyomas are cytogenetically characterized by consistent, clonal chromosome abnormalities, including t(12;14)(q14-15;q23-24) and other rearrangements of 12q14-15 that occur without any visible 14q changes. The partly similar banding characteristics of these two regions have hitherto precluded exact mapping of the 12q and 14q breakpoints to any particular band, let alone their assignment to subbands. In the series of four myomas presented here, in which one tumor had inv(12q), two t(12;14), and one a three-way t(7;12;14), we were able to achieve high resolution banding (550 band stage) of the rearranged chromosomes in several metaphases. This enabled us to assign a 12q breakpoint to 12q15 in all tumors and, in the three cases informative in this regard, the 14q breakpoint to 14q24.1. The more precise breakpoint mapping considerably narrows down the area that must be examined with molecular genetic methods in order to identify the gene loci that are rearranged in leiomyomas with 12q and 14q aberrations. It will also help determine to what extent leiomyoma rearrangements of 12q involve the same loci that are affected in 12q changes in other tumor types, e.g., in pleomorphic adenomas of the salivary gland, in lipomas, and in myxoid liposarcomas. At present it seems that the breakpoint in 12q may be cytogenetically identical in the three benign tumors, whereas it in myxoid liposarcomas appears to be more proximal.     

Cytogenetic and histologic findings in 17 pulmonary chondroid hamartomas: Evidence for a pathogenetic relationship with lipomas and leiomyomas

Pulmonary chondroid hamartomas (PCH) are benign tumors that contain mesenchymal and epithelial components. In this series, we identified clonal chromosome aberrations in mesenchymal cells from 10 of 17 PCH. Chromosome band 12q15 was rearranged most frequently (N = 4), and one case had a t(12;14)(q15;q24) that was identical cytogenetically to the characteristic translocation in uterine leiomyomas. Histologic review revealed diverse mesenchymal populations, including undifferentiated cells, cartilage, adipose tissue, and smooth muscle, in most of the PCH. These findings suggest that PCH result from neoplastic transformation of a primitive mesenchymal cell that differentiates along chondroid, adipose, and smooth muscle pathways.     

PAC clone containing the HMGI(Y) gene spans the breakpoint of a 6p21 translocation in a uterine leiomyoma cell line

Akin to the HMGI-C rearrangements observed in benign solid tumors with 12q14–15 abnormalities, the HMGI(Y) gene has been assumed to play a crucial role in tumors with 6p21 abnormalities. Fluorescence in situ hybridization (FISH) studies using a PAC clone containing the HMGI(Y) gene as a molecular probe have been performed on a cell line from a uterine leiomyoma with a complex translocation involving chromosomal band 6p21.3. The results revealed that the breakpoint mapped within the PAC clone as reflected by signals on the normal chromosome 6 and both derivative chromosomes 1 and 14. Thus, the breakpoint was located within the HMGI(Y) gene or its close vicinity. These findings support the idea that HMGI(Y) rearrangements are causally related to the origin of uterine leiomyomas with 6p21 abnormalities. Genes Chromosom Cancer 17:191–193 (1996). © 1996 Wiley-Liss, Inc.     

A uterine leiomyoma showing both t(12;14) and del(7) abnormalities

The involvement of chromosomes 12 and 14 in uterine leiomyomas has been well established. However, in a recent report of only a del(7)(q22.1q31.32) or (q11.2q22.3) in two cases of typical uterine leiomyoma, Boghosian et al. hypothesized that this could represent a cytogenetic subgroup of uterine leiomyomas. We report a case of uterine leiomyoma with both the t(12;14) and del(7) in all the cells examined and discuss the implications of this in terms of critical chromosomal rearrangements underlying the route to benign cellular proliferation.     

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. © 2012 Wiley Periodicals, Inc.     

Oncofetal protein IMP3: a useful diagnostic biomarker for leiomyosarcoma

An accurate diagnosis between leiomyoma and leiomyosarcoma is essential for patient management. IMP3 is a member of the insulin-like growth factor (IGF-II) mRNA binding protein (IMP) family that consist of IMP1, IMP2, and IMP3. IMP3 is an oncofetal protein associated with aggressive and advanced tumors and is specifically expressed in malignant tumors but not found in benign tissues. The aim of this study was to determine the expression and diagnostic value of IMP3 in leiomyoma and leiomyosarcoma. A total of 216 cases (resection, n = 183; biopsy, n = 33) consisting of 82 leiomyosarcomas (uterine, n = 15; soft tissue, n = 67), 62 leiomyomas (uterine, n = 50; soft tissue, n = 12), and 72 uterine-variant leiomyomas (atypical, n = 19 [14%]; cellular, n = 21 [16%]; mitotically active, n = 12 [9%]; myxoid, n = 11 [8%]; vascular, n = 3 [2%]; epithelioid, n = 1 [1%]; benign metastasizing, n = 1 [1%]; and smooth muscle tumors of uncertain malignant potential, n = 4) were examined by immunohistochemistry for IMP3 expression. IMP3 showed strong cytoplasmic staining in 43 (52%) of 82 leiomyosarcomas, regardless of histologic grades. There was no difference in IMP3 expression between uterine and soft tissue leiomyosarcomas. In contrast to malignant tumors, IMP3 expression was not found in any of the typical leiomyomas (0/62 cases). All uterine-variant leiomyomas were negative, except for 3 cases (atypical variant, n = 2; cellular variant, n = 1) for IMP3 staining. In summary, we are the first to describe IMP3 expression in smooth muscle tumors. Our findings indicate that the expression of IMP3 in both uterine and soft tissue leiomyosarcomas can be used as a positive biomarker to increase the level of confidence in establishing a definitive diagnosis of a malignant smooth muscle tumor.