Dinucleotide repeat polymorphisms of RAD51, BRCA1, BRCA2 gene regions in breast cancer

Recent studies suggest that genetic polymorphisms of the DNA repair genes have been implicated in breast cancer risk. BRCA1 and BRCA2 , two breast cancer susceptibility genes, are essential to maintain chromosomal integrity. This is mediated via regulation of RAD51 during homologous recombination. Dinucleotide polymorphism repeats in the 15q14–21, 17q21 and 13q12–13 regions, where the RAD51 , BRCA1 and BRCA2 genes are located, respectively, have been evaluated. The polymorphism was determined using the following microsatellite markers: D15S118, D15S214, D15S1006, D17S855, D17S1323, D13S260 and D13S290. Genotypes containing the (CA)₁₇ or (CA)₁₉ alleles in the RAD51 region were found to be associated with a decreased breast cancer risk. Genotype containing the (CA)₁₇ allele in the 13q12–13 region was found to be associated with an increased breast cancer risk. The results indicate that dinucleotide CA repeat polymorphism at RAD51 and BRCA2 gene regions might be associated with genetic susceptibility to breast cancer.     

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

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

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.     

Ring formation and structural rearrangements of chromosome 1 as secondary changes in uterine leiomyomas with t(12;14)(q14-15;q23-24)

Cytogenetic analysis of short-term cultures from two uterine leiomyomas revealed, in addition to the primary abnormality, the reciprocal translocation t(12;14)(q14-15;q23-24), secondary structural changes that in both cases included ring chromosomes and rearrangements of chromosome 1. One tumor had the karyotype 46,XX,r(1)(p34q32),ins(8;9)(q13;q13q22),t(12;14)(q14-15;q23- 24). Massive numerical rearrangements were found in the second leiomyoma, with chromosome numbers ranging from 47 to 92. In spite of this variability, two main cell populations could be discerned, one near-diploid, the other hypotetraploid, with most mitoses having chromosome numbers between 80 and 88. These findings were corroborated by flow cytometry, which revealed two peaks corresponding to DNA indexes of 0.97 and 1.77. The structural abnormalities t(1;1)(p31;q44) and t(12;14)(q14-15;q23-24) were present in all karyotypically abnormal cells, and one or more unidentified ring chromosomes were observed in most of the hypotetraploid mitoses. In no cells were double copies of the t(1;1) and t(12;14) rearrangements detected. The similarity between the secondary changes in the cases reported here suggests that clonal evolution in uterine leiomyoma is nonrandom.     

Intravenous leiomyomatosis: molecular and cytogenetic analysis of a case.

Apart from its hormone responsiveness, little about the pathobiology of intravenous leiomyomatosis (IVL), a rare smooth muscle proliferation, is known. We investigated the cytogenetics and molecular biology of IVL in a 40-year-old female who presented with an abrupt onset of dyspnea. In addition to the intracaval tumor mass composed of histologically benign smooth muscle, four distinct retroperitoneal "fibroids" were cytogenetically investigated. An identical abnormal karyotype, 45,XX,der(14)t(12; 14)(q15;q24),-22, was observed in all five specimens. Fluorescence in situ hybridization revealed three copies of HMGIC (alias HMGA2), two on the normal chromosomes 12 at 12q15, as well as another on the der(14) in the breakpoint region, suggesting that the 12q breakpoint occurred 5' (centromeric) to HMGIC (HMGA2), as has been frequently observed in uterine leiomyoma. Such similarity in chromosomal rearrangements suggests that there may be a pathogenetic relationship between IVL and uterine leiomyomata with t(12;14). Skewed X inactivation was observed in each tumor sample, but not in the myometrium. In each tumor, the lower molecular weight allele of HUMARA was nonrandomly inactivated. This pattern of X inactivation is most consistent with origin from a single transformation event, and in this regard, IVL more closely resembles disseminated peritoneal leiomyomatosis than typical uterine leiomyomata.     

Consistent breakpoints in region 14q22-q24 in uterine leiomyoma

The chromosomes of nine consecutive human benign leiomyomas of the uterus were studied with banding methods following short-term culture. All of the tumors had a typical benign histology. Five exhibited clonal chromosome changes including three with consistent involvement of chromosomes 12 and 14 in a translocation, t(12;14)(q14-15;q23-q24), a direct insertion, dir ins(12;14)(p11.2;q22q24.1), and a direct insertion, dir ins(14;12)(q22-q23;q14-q15q23-q24.1). Thus, this study demonstrated the presence of consistent chromosome changes in another benign proliferation. Strikingly, the breakpoint observed at 12q14-q15 in two specimens is also involved nonrandomly in other benign proliferations such as mixed salivary gland tumors and lipomas. However, region 14q22-q24, which was involved in three specimens, may contain a DNA sequence critical for the genesis of uterine leiomyoma.     

Complex karyotypic changes, including rearrangements of 12q13 and 14q24, in two leiomyosarcomas

Cytogenetic investigation of short-term cultures from two leiomyosarcomas revealed complex karyotypic changes in both cases. The first tumor, a subcutaneous leiomyosarcoma of the knee, had the karyotype 70-80,XY, +X, +Y, +1, +1, +2, +2, +3, +3, +4, +4, +7, +7, +8, +8, +9, +10, +15, +15, +16, +16, +18, +19, +20, +21, +21, +22, +22,t(?;5)(5;21)(?;q35p11;q11), t(?;5)(5;21)(?;q35p11;q11), +del(11)(q22),der(13)t(12;13)(q13;q22),der(14)t(9;14)(p11;p11), +14p+, +t(20;?)(q13;?), +t(20;?)(q13;?), +2 mar. A polyploidized clone with 120-150 chromosomes was also observed. DNA flow cytometry revealed only one abnormal peak, corresponding to a DNA index of 1.76. The other tumor, a uterine leiomyosarcoma, had the karyotype 61-67, X, -X, +1, +3, +5, +6, +7, +8, +9, +12, +13, +15, +t(1;1)(p32;q32), +der(1)t(1;8)(p13;q11), +del(2)(p11), +del(2)(q22), +del(2)(q22), +del(3)(p13), +i(5p),t(8;14)(q24;q24), +der(8)t(8;14) (q24;q24), +del(10)(p12),der(11)t(11;15)(p15;q11),t(16;?)(p13;?),t(16;?)(q24;?), der dic(17) (17pter----cen----17q25::hsr::17q25----cen----17pte r), +t(19;?)(p13;?), +der dic(20)(20pter----cen----20q12::hsr::20q12----cen----+ ++20pter), +mar. The DNA index was 1.59. The finding in these leiomyosarcomas of rearrangements of the same regions of chromosomes 12 and 14 that are involved in the tumor-specific t(12;14)(q14-15;q23-24) of uterine leiomyoma indicates that the same genes in 12q and 14q might be important in the pathogenesis of benign and malignant smooth muscle tumors.     

Endometrial stromal sarcoma with clonal complex chromosome abnormalities. Report of a case and review of the literature.

Only eleven endometrial stromal sarcomas (ESS) with clonal chromosomal abnormalities have been reported in the literature. Of these, four have been reported to harbor the t(7;17) translocation. We report here an additional ESS that exhibited clonal complex chromosome abnormalities not described earlier: 38,XX,-1,del(1)(q11),-2,add(2)(p13),-3,der(4)add(4)(p12)psu dic(4;14)(q35;q11.2), add(6)(p21.3),add(7)(q22),del(7)(p11.2p13),-8,-9,add(9)(q34),- 10,add(10)(q24),-11,-11,ins(12;?) (q13;?),-14,-14,-15,ins(15;?)(q22;?),add(16)(q22),add(17)(q11.2),- 18,der(18)t(7;18)(q11.2;p11.2),-19, add(20)(p13),add(21)(p11.2),-22,add(22)(p11.2),+6mar in metaphase cells from primary short-term culture.     

Identification,molecular cloning,and characterization of the chromosome 12 breakpoint cluster region of uterine leiomyomas

Recent molecular cytogenetic analysis of uterine leiomyoma cell lines with chromosome 12 aberrations has indicated that their chromosome 12 breakpoints map between linkage locus D12S8 and the CHOP gene. Here, we report fluorescence in situ hybridization (FISH) and molecular cloning studies of the chromosome 12 breakpoints in a panel of seven such uterine leiomyoma cell lines; five with the frequently observed t(12; 14)(q15;q24), one with t(12;15)(q15;q24), and one with ins(12;11)(q14;q21 qter). Directional chromosome walking studies starting from D12S8 and the CHOP gene resulted in the isolation of a relatively large number of overlapping YAC clones, including Y5355 (465 kbp), Y7673 (360 kbp), and Y9899 (275 kbp). In total, the inserts of these three YAC clones span an 800 kbp long and presumably contiguous stretch of human genomic DNA. All chromosome 12 breakpoints of the uterine leiomyoma cell lines studied were found by FISH analysis to be mapping within a 445 kbp subfragment of this region and, furthermore, to be dispersed over a DNA region which is at least 150 kbp in size. The chromosome 12 breakpoint of t(12;14)(q15;q24) in uterine leiomyoma cell line LM-30.1/SV40 was tentatively mapped within the 60 kbp region between YAC clones Y9899 and Y5355. From this 60 kbp region and close to sequencetagged site RM99, we isolated probe pRM 118-A, which showed in Southern blot analysis that it detected a rearrangement in LM-30.1/SV40 DNA, and generated restriction maps of the normal and rearranged genomic DNA regions detected with this probe. Finally, we molecularly cloned part of one of those rearranged DNA fragments using a vectorette-PCR-based technique and demonstrated that it consisted of 12q13-q15 sequences fused to DNA sequences derived from 14q23-24 and most likely represented the translocation junction on der(14) in LM-30.1/SV40 cells. Our studies strongly suggest that we have identified and isolated the uterine leiomyoma cluster region of chromosome 12 breakpoints, which we designate ULCR12, and molecularly cloned and characterized the der(14) translocation junction in cells derived from a uterine leiomyoma carrying the frequently observed t(12;14)(q15;q24).     

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.     

Clonal structural chromosome aberrations in fibrous dysplasia

Cytogenetic analysis of short-term cultures from a case of monostotic fibrous dysplasia in a 14-year-old girl revealed multiple clonal structural rearrangements with evidence of clonal evolution. The karyotype was 46,XX,del(3)(q27),add(10)(q22), add(12)(p13)/46,idem,t(3;8)(p21;q13),add(10)(q26),der(15)del(15)(q15q22)ins(15;?)(q15;?)/46,idem,-X, + 2,t(3;8),add(10),der(15). The finding of clonal structural aberrations suggests that fibrous dysplasia is a neoplastic lesion which develops as the result of somatic mutations.     

Aggressive angiomyxoma with t(12;21) and HMGA2 rearrangement: report of a case and review of the literature

Conventional cytogenetic analysis of an aggressive angiomyxoma of the rectal wall of a 72-year-old woman revealed a translocation between the long arms of chromosomes 12 and 21, with the karyotype 46,XX,t(12;21)(q15;q21.1). Involvement of the HMGA2 gene locus (12q15) was confirmed by fluorescence in situ hybridization using an HMGA2 breakpoint flanking probe set performed on metaphase and interphase cells from an in situ culture of fresh lesional tissue. Karyotypic rearrangements of 12q13 approximately q15 are considered recurrent in aggressive angiomyxoma, although reported in only five previous cases. Translocation partner chromosome 21 is unique to the present case.     

Familial occurrence of thymoma and autoimmune diseases with the constitutional translocation t(14;20)(q24.1;p12.3)

Thymomas are low-grade epithelial cancers of the thymus whose prevalence varies between 0.1/100,000 and 0.4/100,000. Familial occurrence of thymoma is very rare. We studied a family bearing the constitutional chromosome translocation t(14;20)(q24;p12), 3 of whose members had a thymoma. In this family, among 27 patients, 11 had the translocation: 3 had thymoma and 4 others had 5 different autoimmune diseases: type 1 diabetes mellitus, Graves' disease, pernicious anemia, primitive Sj?gren disease, and autoimmune pancytopenia. FISH studies allowed us to be more specific about the translocation breakpoints. The 14q24 breakpoint was in intron 5 of RAD51L1, and the 20p12 breakpoint was 100 kb telomeric to BMP2. RAD51L1 is a tumor-suppressor gene belonging to the RAD51 family, already implicated in many tumors (uterine leiomyomas, pseudo-Meigs syndromes, pulmonary chondroid hamartomas) and involved in recombinational repair of DNA double-strand breaks. BMP2 belongs to the TGFbeta superfamily, and the BMP2-BMP4 genes are involved in thymocyte differentiation by blocking progression from CD4-CD8- to CD4+CD8+ while maintaining a sufficient pool of immature precursors. Dysregulation of RAD51L1 and/or BMP2 may explain this familial occurrence of thymomas and autoimmune diseases. Using QRT-PCR, we studied the expression of BMP2 in 20 sporadic thymomas and found various levels of expression that may be associated with autoimmune diseases.     

Identification of four new translocations involving FGFR1 in myeloid disorders

The 8p11 myeloproliferative syndrome (EMS) is associated with three translocations, t(8;13)(p11;q12), t(8;9)(p11;q33), and t(6;8)(q27;p11), that fuse unrelated genes (ZNF198, CEP110, and FOP, respectively) to the entire tyrosine kinase domain of FGFR1. In all cases thus far examined (n = 10), the t(8;13) results in an identical mRNA fusion between ZNF198 exon 17 and FGFR1 exon 9. To determine if consistent fusions are also seen in the variant translocations, we performed RT-PCR on four cases and sequenced the products. For two patients with a t(8;9), we found that CEP110 exon 15 was fused to FGFR1 exon 9. For two patients with a t(6;8), we found that FOP exon 5 (n = 1) or exon 7 (n = 1) was fused to FGFR1 exon 9. To determine if FGFR1 might be involved in other myeloid disorders with translocations of 8p, we developed a two-color FISH assay using two differentially labeled PAC clones that flank FGFR1. Disruption of this gene was indicated in a patient with a t(8;17)(p11;q25) and Ph-negative chronic myeloid leukemia in association with systemic malignant mast cell disease, a patient with acute myeloid leukemia with a t(8;11)(p11;p15), and two cases with T-cell lymphoma, myeloproliferative disorder, and marrow eosinophilia with a t(8;12)(p11;q15) and ins(12;8)(p11;p11p21), respectively. For the patient with the t(8;11), the chromosome 11 breakpoint was determined to be in the vicinity of NUP98. We conclude that 1) all mRNA fusions in EMS result in splicing to FGFR1 exon 9 but breakpoints in FOP are variable, 2) two-color FISH can identify patients with EMS, and 3) the t(8;17)(p11;q25), t(8;11)(p11;p15), t(8;12)(p11;q15), and ins(12;8)(p11;p11p21) are novel karyotypic changes that most likely involve FGFR1.     

Chromosome rearrangements in two uterine sarcomas

Cytogenetic analysis of short-term cultures from two uterine sarcomas revealed clonal chromosome abnormalities in both cases. A locally recurrent mixed mesodermal tumor had the karyotype 61,XX,+2,+3,+del(5)(q11),+6,+7,+del(7)(q32),+8,+8,+8,+10, -11,-11,+der(11)t(1;11)(q12;p15),+der(11)t(1;11)(q12;p15),+der(11)t(1;11)(q12;p15),+del(12)(q14q21),+13,+15,del(17)(q23),+20. The other tumor, a lung metastasis from a uterine leiomyosarcoma, had several karyotypically abnormal clones. Two of them consisted of highly aberrant cells with modal chromosome numbers of 82 and 153, respectively, but because of insufficient quality the complex anomalies could not be identified. Various chromosomal changes that included translocations, deletions, insertions, and numerical rearrangements (always with extra chromosome 7 material) were identified in pseudo- or near-diploid cells, resulting in nine additional cytogenetically abnormal clones.