Variant Ph translocations in chronic myeloid leukemia

Variant translocations were found in eight of 142 consecutive patients with Ph-positive, chronic myeloid leukemia encountered in our laboratory during the last decade. Two patients had simple, two-way variant translocations: t(17;22)(p13;q11) and t(16;22)(q24;q11). Both of these patients had an additional translocation involving chromosomes #9: t(7;9)(q22;q34) and t(9;17)(q34;q21), respectively. Complex variant translocations were found in four cases: t(2;9;22)(p23q12;q34;q11), t(3;9;22)(p21;q34;q11), t(9;12;22)(q34;q13;q11q13), and t(13;17;22)(p11;p11q21;q11). In two cases, the only discernable cytogenetic aberration was del(22)(q11). A review of the chromosomal breakpoints involved in this series and in 185 cases of variant Ph translocations previously reported in the literature reveals that a disproportionately large number of breakpoints are located in light-staining regions of G-banded chromosomes. Furthermore, the breakpoints in simple variant translocations are more often located in terminal chromosomal regions, whereas, the breakpoints in complex translocations typically affect nonterminal bands. No obvious correlation was detected between variant Ph translocation breakpoints and either fragile sites, oncogene locations, or consistent chromosome breakpoints in other malignancies.     

Molecular cytogenetic mapping of recurrent chromosomal breakpoints in tenosynovial giant cell tumors

Tenosynovial giant cell tumor (TGCT) is the most common benign tumor of synovium and tendon sheath. Cytogenetic data indicate that 1p11-13 is the region most frequently involved in structural rearrangements. With the aim of eventually identifying the genes associated with TGCT development, we have investigated 1p11-13 breakpoints using fluorescence in situ hybridization (FISH) analysis, with a panel of yeast artificial chromosome (YAC) probes covering 1p11-21. Twenty-six tumors were analyzed by G-banding, and 24 of these showed a breakpoint in 1p11-13. The cytogenetic findings add to previous observations that, among a variety of translocations involving 1p11-13, chromosome 2 is the most common translocation partner, with a breakpoint in 2q35-37. This aberration was found in eight cases. Other recurrent translocation partners, found in two or three cases, were 5q22-31, 11q11-12, and 8q21-22. Material from 21 tumors was available for FISH analysis, which revealed that the breakpoints clustered to one region spanned by two YAC probes, 914F6 and 885F12 located in 1p13.2, in 18 cases. Bacterial artificial chromosome probes were used to map the recurrent breakpoint on chromosome 2. In four of seven cases there was a breakpoint within the sequence covered by probe 260J21, where the RDC1 gene is located, a gene reported to fuse with HMGIC in lipomas with a 2;12 translocation.     

Promiscuous translocations of chromosome arm 17q in human neuroblastomas

Deletions of chromosome arm 1p and amplification of the MYCN oncogene are well-recognized genetic changes in neuroblastoma cells. Technical difficulties in cytogenetic analysis of this tumour have hampered the recognition of other recurring abnormalities, but recent use of molecular cytogenetic techniques has indicated significant involvement of chromosome arm 17q. In primary tumours and in cell lines, a recurrent unbalanced translocation t(1p;17q) has been identified by fluorescence in situ hybridization. We confirm the occurrence of this translocation in primary tumours and, in addition, we describe seven new structural rearrangements all of which result in gain of 17q in tumour cells. These rearrangements involved chromosome arms 9p, 10q, 11p, 14q, and 16q. Triplication of the 17q arm was seen in one case. The 17q breakpoint was most commonly q21. All these 17q changes were found in near-diploid tumours. We have also reviewed the literature for neuroblastoma karyotypes involving 17q abnormalities; taken in conjunction with our findings this indicates a remarkable promiscuity of translocation partners, with more than 20 different chromosome regions involved in 17q translocations. Genes Chromosom. Cancer 19:143–149, 1997 © 1997 Wiley-Liss Inc.     

Chromosomal alterations in 15 breast cancer cell lines by comparative genomic hybridization and spectral karyotyping

Breast cancer cell lines have been widely used as models in functional and therapeutical studies, but their chromosomal alterations are not well known. We characterized the chromosomal aberrations in 15 commonly used human breast carcinoma cell lines (BT-474, BT-549, CAMA-1, DU4475, MCF7, MDA-MB-134, MDA-MB-157, MDA-MB-361, MDA-MB-436, MPE600, SK-BR-3, T-47D, UACC-812, UACC-893, and ZR-75-1) by comparative genomic hybridization (CGH) and spectral karyotyping (SKY). By CGH the most frequent gains were detected at 1q, 8q, 20q, 7, 11q13, 17q, 9q, and 16p, whereas losses were most common at 8p, 11q14-qter, 18q, and Xq. SKY revealed a multitude of structural and numerical chromosomal aberrations. Simple translocations, typically consisting of entire translocated chromosome arms, were the most common structural aberrations. Complex marker chromosomes included material from up to seven different chromosomes. Evidence for a cytogenetic aberration not previously described in breast cancer, the isoderivative chromosome, was found in two cell lines. Translocations t(8;11), t(12;16), t(1;16), and t(15;17) were frequently found, although the resulting derivative chromosomes and their breakpoints were strikingly dissimilar. The chromosomes most frequently involved in translocations were 8, 1, 17, 16, and 20. An excellent correlation was found between the number of translocation events found by SKY in the individual cell lines, and the copy number gains and losses detected by CGH, indicating that the majority of translocations are unbalanced. Genes Chromosomes Cancer 28:308-317, 2000.     

Cytogenetic features of twenty-six primary breast cancers.

Tumor preparations from 26 primary breast cancers were studied cytogenetically with G-banding, using a direct technique, synchronized short-term culture, or both. Two tumors had normal karyotypes, and 24 (92%) had chromosomal abnormalities. Nineteen tumors had chromosome 1 rearrangements, with 10 cases (40%) displaying distal short arm translocations (1p36). Other frequent breakpoints occurred at 3p21, 6q22-27, 11q21-25, 16q22-24, 17p, and 19q13. To seek primary rather than secondary cytogenetic changes, attention was directed toward tumors with diploid-range karyotypes (32-57 chromosomes per cell). Of four such tumors, three exhibited nonrandom involvement of chromosome 16q22. This, together with previously reported data, suggests that deletion or rearrangement of chromosome 16q21-24 may be a primary or specific event in a subset of breast cancers.     

Chromosomes in kidney, ureter, and bladder cancer

Although Wilms tumor has been a favored subject for cytogenetic investigation, little is known about chromosomes in adult urinary tract cancers. For this reason, we excluded Wilms' tumor and studied a series of 32 adult urinary tract tumors. Nineteen tumors had detectable autosomal abnormalities. Each of ten renal tumors (consisting of eight renal cell and two transitional cell carcinomas) had three or more chromosome abnormalities. Two candidates for primary chromosome changes in renal cancer are rearrangement of 3p14 and an unbalanced translocation with breakpoints of 5q13 and 14q22. Trisomy 20 is a frequent secondary change. Other nonrandom changes in renal cancer are rearrangements of 1q and +7, -8, -9, -14, -15, +16, and deletions of 17p. Eight bladder and a ureter tumor were all transitional cell carcinomas. Two bladder and the ureter tumor had only one detectable abnormality: deletions of 10q24 and 21q22 and +7, respectively. Other nonrandom bladder changes were -9, +13, +15, and +20. From a cytogenetic standpoint, adult urinary tract tumors appear to be chromosomally complex but critical consistencies are emerging.     

Chromosome aberrations in 35 primary ovarian carcinomas.

Cytogenetic analysis was performed on short-term cultures of primary ovarian carcinomas from 62 patients. Cytogenetic analysis was successful in 59 cases. Clonal chromosome aberrations were detected in 35 tumors. Only numerical changes or a single structural change were found in five carcinomas: trisomy 12 was the sole anomaly in two tumors, one tumor had the karyotype 50,XX, + 5, + 7, + 12, + 14, a fourth tumor had a balanced t(1;5), and the fifth tumor had an unbalanced t(8;15). The fact that four of these five carcinomas were well differentiated suggests that simple karyotypic changes are generally characteristic of these less aggressive ovarian tumors. The majority of the cytogenetically abnormal tumors (n = 30) had complex karyotypes, with both numerical and structural aberrations and often hypodiploid or near-triploid stemlines. The numerical imbalances (comparison with the nearest euploid number) were mostly losses, in order of decreasing frequency -17, -22, -13, -8, -X, and -14. The structural aberrations were mostly deletions and unbalanced translocations. Recurrent loss of genetic material affected chromosome arms 1p, 3p, 6q, and 11p. The breakpoints of the clonal structural abnormalities clustered to several chromosome bands and segments: 19p13, 11p13-15, 1q21-23, 1p36, 19q13, 3p12-13, and 6q21-23. The most consistent change (16 tumors) was a 19p + marker, and in 12 of the tumors the 19p + markers looked alike.     

Novel 6p rearrangements and recurrent translocation breakpoints in retinoblastoma cell lines identified by spectral karyotyping and mBAND analyses

Gain of the short arm of chromosome 6, usually through isochromosome 6p formation, is present in approximately 50% of retinoblastoma tumors. The minimal region of gain maps to chromosome band 6p22. Two genes, DEK and E2F3, are implicated as candidate oncogenes. However, chromosomal translocations have been overlooked as a potential mechanism of activation of oncogenes at 6p22 in retinoblastoma. Here, we report combined spectral karyotyping), 4',6-diamidino-2-phenylindole banding, mBAND, and locus-specific fluorescence in situ hybridization analyses of four retinoblastoma cell lines, RB1021, RB247c, RB383, and Y79. In RB1021 and RB247c, 6p undergoes structural rearrangements involving a common translocation breakpoint at 6p22. These data imply that 6p translocations may represent another mechanism of activation of 6p oncogene(s) in a subset of retinoblastomas, besides the copy number increase. In addition to 6p22, other recurrent translocation breakpoints identified in this study are 4p16, 11p15, 17q21.3, and 20q13. Common regions of gain map to chromosomal arms 1q, 2p, 6p, 17q, and 21q.     

Nonrandom structural and numerical chromosome changes in non-small-cell lung cancer

Cytogenetic studies were performed on 27 tumor cell lines (most of which were derived from metastatic lesions) and four fresh malignant pleural and pericardia! effusions from 30 patients with non-small-cell lung cancer (non-SCLC). Many clonal structural (deletions and nonreciprocal translations) and numerical abnormalities were found in each specimen. Statistical analysis revealed these changes were nonrandomly distributed among the chromosomes. A statistically significant number of chromosomal breakpoints were seen in regions 1 q 1, 1 q3, 3p1, 3p2, 3q1, 3q2, 7q1, 13p1, 14p1, 15p1, and 17q1 when the regions were compared to the total haploid complement. In addition, when a given region was compared to other regions within the same chromosome, statistically significant numbers of breakpoints were noted for regions 1q3, 5q1, 7q1, 13p1, 14p1, 15p1, 16q2, 17q1, and 21p1. Specific chromosome bands showing the most frequent involvement in structural abnormalities were (in descending order) 3p 14.2, 3q21, 19q13, 11p15, 1q11, 7q111, 1q21, 3p23, and 3p21. The breakpoints indicate areas to look for new dominant oncogenes activated by translocations, while the areas of deletions and loss of material by nonreciprocal translocations highlight areas to search for recessive oncogenes. These cytogenetic studies represent strong evidence that multiple genetic lesions are associated with the development of metastatic lung cancer, and provide a roadmap to search for new genes involved in the pathogenesis of lung cancer.     

Cytogenetic evaluation of a large series of hepatoblastomas: numerical abnormalities with recurring aberrations involving 1q12-q21

Hepatoblastoma is a malignant embryonal liver tumor that occurs almost exclusively in infants and very young children. Previous cytogenetic studies of hepatoblastoma have investigated small series or individual cases. This report is on the cytogenetics of a large series of 111 hepatoblastoma specimens, with cytogenetic results consecutively karyotyped over a 12-year period. Abnormal karyotypes were observed in 55 cases (approximately 50% of the total). Numerical aberrations were observed in 41 cases (36% of the total), particularly trisomies of chromosomes 2, 8, and 20. Chromosome losses were less common than chromosome gains. Structural abnormalities were observed in 43 cases (39% of the total). Unbalanced translocations resulting in trisomy 1q and involving breakpoints at 1q12-21 were the most common structural abnormality, observed in 20 tumors (18% of total cases); the corresponding translocated chromosome was highly varied. The previously reported t(1;4) was observed in seven cases. Most tumors with translocations involving 1q12-21 also displayed numerical chromosome aberrations, the most common of which were chromosomal trisomies, whereas tumors with other structural rearrangements had fewer numerical abnormalities.     

Cytogenetic analysis of 57 primary prostatic adenocarcinomas.

Cytogenetic analysis after short-term culture in vitro of primary tumor samples was attempted in 82 patients with prostatic cancer. Tumor material was obtained by radical prostatectomy or transurethral resection. Successful cytogenetic studies were performed on 57 tumors of which five were well, 30 moderately, and 22 poorly differentiated adenocarcinomas. Only normal karyotypes were found in 24 tumors. Structural nonclonal aberrations were detected in 18 and clonal karyotypic abnormalities in 15 tumors. The most common clonal numerical aberration was loss of the Y chromosome; a missing Y was found in six tumors, in three of these as the sole anomaly. Clonal structural chromosomal rearrangements, usually accompanied by numerical changes, were detected in 12 tumors. The rearrangements involved 18 of the 22 autosomes and the X chromosome. Chromosomes 1, 7, and 10 were most frequently affected. Deletions, duplications, inversions, insertions, and balanced as well as unbalanced translocations were represented. The breakpoints in chromosome 1 were scattered along both the short and long arms with no obvious clustering, whereas those in chromosomes 7 and 10 were clustered at bands 7q22 (two deletions and two duplications in four different tumors) and 10q24 (two translocations, one deletion, and one inversion in four tumors). One additional tumor displayed a derivative chromosome 10 with a breakpoint in 10q23, and one had monosomy 10. Altogether, these abnormalities resulted in loss of 10q24----qter in five tumors. Monosomy 8 and rearrangements of the short arm of chromosome 8 leading to loss of 8p21----pter were seen in four tumors. Double minute chromosomes were found in two tumors.     

A constitutional bws-related t(11;16) chromosome translocation occurring in the same region of chromosome 16 implicated in wilms' tumors

Beckwith-Wiedemann syndrome (BWS) is a congenital overgrowth disorder with a varying spectrum of clinical manifestations including macroglossia, omphalocele, hemihypertrophy, and a predisposition to a subset of embryonal tumors, most frequently Wilms' tumor (WT). A variety of cytogenetic, genetic linkage, and molecular mapping data implicate a gene or genes on chromosome band 11p15.5 in BWS and its related tumors. However, some families with BWS do not show linkage to 11p15, and other alterations have been found in Wilms' tumors as well. One such alteration is loss of heterozygosity (LOH) for chromosome arm 16q. Here we have analyzed a balanced t(11;16)(p15;q13) chromosomal translocation associated with the BWS phenotype and mapped the breakpoint positions for both chromosomes 11 and 16 by using somatic cell hybrids and polymorphic markers. The chromosome 11 breakpoint was found to lie distal to the D11S12 locus, but proximal to TH on 11p15.5, a region shown previously to contain other BWS-related chromosomal events. The chromosome 16 breakpoint was distal to D16S290 in 16q13, but proximal to loci D16S265, D16S267, and D16S164 in band 16q21. This area encompasses the region of LOH occurring through mitotic recombination in sporadic WT. This raises interesting possibilities for the genetic and epigenetic involvement of both chromosomal regions (11p15 and 16q13) in the pathogenesis of BWS and Wilms' tumor.     

Multiple reciprocal translocations in salivary gland mucoepidermoid carcinomas

Mucoepidermoid carcinoma, the most common human malignant salivary gland tumor, can arise from both major and minor salivary glands, including sites within the pulmonary tracheobronchial tree. We performed comparative genomic hybridization (CGH) and spectral karyotyping (SKY) on two tumor cell lines: H3118, derived from tumor originating in the parotid gland, and H292, from tumor in the lung. In both cell lines, CGH showed a partial gain within the short arm of chromosome 7 and SKY revealed the presence of the previously reported reciprocal translocation t(11;19)(q21;p12). Additional chromosomal rearrangements were found in both cell lines, including three more reciprocal translocations in cell line H292 [t(1;16), t(6;8)x2] and three other reciprocal translocations in cell line H3118 [t(1;7), t(3;15), and t(7;15)]. A review of the literature of other reported cases of mucoepidermoid carcinomas analyzed with standard G-banding techniques, as well as distinct benign salivary gland tumors, such as pleomorphic adenomas and Warthin tumor, confirmed the presence of a karyotype dominated by reciprocal translocations. Four chromosomal bands were involved in chromosomal translocations in both cell lines: 1q32, 5p15, 7q22, and 15q22. Fluorescence in situ hybridization studies showed that the breakpoints in these four bands were often within a few megabases of each other. The involvement of similar chromosomal bands in breakpoints in these two cell lines suggests that these regions may be predisposed or selected for chromosomal rearrangements in this tumor type. The presence of multiple reciprocal translocations in both benign and malignant salivary gland tumors may also suggest a particular mechanism within mucous or serous glands mediating chromosomal rearrangements.     

Molecular cytogenetic characterization of recurrent translocation breakpoints in bizarre parosteal osteochondromatous proliferation (Nora's lesion)

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is a rare tumorous lesion with aggressive growth that affects primarily the small tubular bones in the distal extremities and often recurs after excision. No previous cytogenetic data on BPOP are available. In the present study, lesions from 5 patients were investigated by chromosome banding and fluorescence in situ hybridization (FISH) analyses. Patient age ranged from 24 to 46 years, and the lesions were located in the fingers in 4 cases and in a toe in 1 case. Histological sections from all 5 tumors were characterized by a mixture of hypercellular cartilage, cancellous bone, and spindle cell components. Samples from 2 patients were available for cytogenetic analysis. One of these showed a normal female karyotype, and the other revealed a balanced translocation, t(1;17)(q32;q21), as the sole anomaly. The translocation was further characterized by 3-color metaphase FISH analyses, using 17 1q32-specific and 18 17q21-specific bacterial artificial chromosome probes, to map the precise location of the breakpoints. Split signals were detected by the RP11-99A19 probe in chromosome 1 and by the RP11-219F9 probe in chromosome 17. To determine whether these rearrangements are characteristic features of BPOP, paraffin-embedded tissue sections from all 5 patients were investigated by interphase FISH analyses. All 5 cases had a break in 1q32, and 4 of the 5 cases showed a break in the 17q21 region. The results strongly indicate that t(1;17)(q32;q21), or variant translocations involving 1q32, are recurrent and unique aberrations in BPOP. Several genes are located within the 2 sequences spanning the breakpoints, and further studies should be performed to determine whether any of these are involved in the formation of a fusion gene.     

Cytogenetic findings in a breast stromal sarcoma. Application of fluorescence in situ hybridization to characterize the breakpoint regions in an 11;19 translocation.

Cytogenetic analysis of a stromal breast sarcoma revealed a complex karyotype that included a reciprocal 11;19 translocation, along with multiple numerical changes, deletions, and other unbalanced structural rearrangements. Karyotypic abnormalities have not been reported previously in this rare neoplasm that arises from mesenchymal breast tissue, and the t(11;19) is of interest because various types of sarcoma are characterized by specific reciprocal translocations. Because of the pericentric nature of the breakpoints on chromosomes 11 and 19 in the t(11;19), classical cytogenetic banding could not reveal the centromeric origin of the translocation derivatives. Using nonisotopic in situ hybridization with chromosome 11 and 19 alpha-satellite probes, the centromere of each derivative chromosome was determined, and the rearrangement was interpreted as a balanced translocation, t(11;19)(q12 or q13.1;p12 or p13.1). This abnormality has not been described previously in any breast tumor.     

A constitutional telomeric translocation showing meiotic instability

Constitutional telomeric translocations are rare chromosome rearrangements. They are thought to occur as a result of chromosome breakage and subsequent ligation with the telomeric sequence of a different chromosome. Most frequently they occur as de novo events and, depending on the donor chromosome breakpoint, may be associated with an abnormal phenotype. We report a case of an unbalanced translocation involving the long arm of chromosome 15 and the short arm of chromosome 8 [45,XY, der(8)t(8;15)(p23.3;q11.2),-15], diagnosed prenatally; the father carried an unbalanced translocation of the long arm of chromosome 15 and the short arm of chromosome 2 [45,XY,der(2)t(2;15)(p25.3;q11.2),-15]. Both translocations were shown to have telomere repeat sequences at the translocation breakpoints. There was no apparent imbalance of euchromatic material in either translocation, and no associated abnormal phenotype.     

Karyotypic characterization of urinary bladder transitional cell carcinomas

Samples from 34 primary transitional cell carcinomas (TCCs) of the bladder were short-term-cultured and processed for cytogenetic analysis after G-banding of the chromosomes. Clonal chromosome abnormalities were detected in 27 tumors and normal karyotypes in 3, and the cultures from 4 tumors failed to grow. Losses of genetic material were more common than gains, indicating that loss of tumor suppressor genes may be of major importance in TCC pathogenesis. There was no clonal heterogeneity within individual tumors, consonant with the view that TCCs are monoclonal in origin. The most striking finding was the involvement of chromosome 9 in 92% of the informative cases, as numerical loss of one chromosome copy in 15 cases, but as structural rearrangement in 8. The changes in chromosome 9 always led to loss of material; from 9p, from 9q, or of the entire chromosome. A total of 16 recurrent, unbalanced structural rearrangements were seen, of which del(1)(p11), add(3)(q21), add(5)(q11), del(6)(q13), add(7)(q11), add(11)(p11), i(13)(q10), del(14)(q24), and i(17)(q10) are described here for the first time. The karyotypic imbalances were dominated by losses of the entire or parts of chromosome arms 1p, 9p, 9q, 11p, 13p, and 17p, loss of an entire copy of chromosomes 9, 14, 16, 18, and the Y chromosome, and gains of chromosome arms 1q and 13q and of chromosomes 7 and 20. The chromosome bands and centomeric breakpoints preferentially involved in structural rearrangements were 1q12, 2q11, 5q11, 8q24, 9p13, 9q13, 9q22, 11p11, and 13p10. Rearrangements of 17p and the formation of an i(5)(p10) were associated with more aggressive tumor phenotypes. There was also a general correlation between the tumors' grade/stage and karyotypic complexity, indicating that progressive accumulation of acquired genetic alterations is the driving force behind multistep bladder TCC carcinogenesis.