Chromosomal losses and gains in meningiomas: comparative genomic hybridization (CGH) study of the whole genome

We investigated chromosomal aberrations in meningiomas using newly developed comparative genomic hybridization (CGH) technique and compared the results with the proliferating potential of the tumors. This technique permits the entire genome to be surveyed in one session of experiments. Our results revealed chromosomal aberrations in 5 out of 10 (50%) of the tumor samples studied. Losses of the distal parts of chromosome 1p (5 out of 10) and 22q (3 out of 10) were the two most frequent chromosomal aberrations. Losses and/or gains in other regions were only sporadic. The MIB-1 staining indices (MIB-SI, %) were 1.9 +/- 0.9% (mean +/- SD) in benign (n = 8), 4.5% in atypical (n = 1), and 11.7% in anaplastic (n = 1) meningiomas. The comparison of MIB-SI between the tumors with (2.3 +/- 0.6%) and without (1.6 +/- 0.3%) chromosomal aberrations demonstrated a trend towards an increased MIB-SI in meningiomas with chromosomal aberrations (p < 0.07) by unpaired Student's t-test. This study suggests that alterations in chromosomes 1p and 22q could be a primary focus of further detailed assessment of tumorigenesis and in understanding the biological behavior of meningiomas.     

Detection of chromosomal aberrations in seminomatous germ cell tumours using comparative genomic hybridization

Comparative genomic hybridization (CGH) was used to evaluate tissue specimens from 16 seminomas in order to elucidate the pathogenesis of germ cell tumours in males. A characteristic pattern of losses and gains within the entire genomes was detected in 94% of the seminomas by comparing the ratio profiles of the tumours with a standard of cytogenetically normal genomic DNA. Losses represented 43% of the total number of alterations often affecting chromosomes and chromosome arms 4, 5, 11, 13q, and 18q. Gains amounted to 57% and were often observed on 1q, 7, 8, 12, 14q, 15q, 21q, and 22q. Aberrations of 12p and 21q appeared most consistently. Results from CGH analysis displayed no relationship to the clinical stages of the malignancy. Some rare aberrations appeared, however, only in clinical stage II and in tumours showing relapse in the contralateral testis following orchiectomy, although the alterations were not present in all of the tumours in question. Losses of 16q13-21 and gains of 9q22.1-22.2 were demonstrated in both groups, while loss of 16p12 and gains of 6p21 and 6q23.3-24 were detected in the latter group as well. In conclusion, a specific pattern of chromosomal alterations was demonstrated in the seminomas by improved detection criteria, which increased specificity and sensitivity. The rare aberrations, which appeared only in tumours in improved detection criteria, which increased specificity and sensitivity. The rare aberrations, which appeared only in tumours in clinical stage II and relapsed tumours, may be linked to tumour progression, invasiveness, and bilateral disease.     

Frequent gains on chromosome arms 1q and/or 8q in human endometrial cancer

Comparative genomic hybridization (CGH) was employed to survey genomic regions with increased and decreased copy number of the DNA sequence in 15 endometrial cancers [10 cases with microsatellite instability positive (MI+) and 5 cases with MI-]. Twelve of these 15 tumors (80%) showed abnormalities in copy number at one or more of the chromosomal regions. There were no regions with frequent chromosomal losses. Conversely, 11 of 15 cases (73%) showed gains on chromosome arms 1q (8/15; 53%) and/or 8q (6/15; 40%). Concordant gains of both chromosome arms 1q and 8q were observed in all three endometrial cancers of histological grade 3. These results suggest that these two chromosomal regions may contain genes whose increased expression contributes to development and/or progression of endometrial carcinogenesis. Two cases were further analyzed by fluorescence in situ hybridization (FISH) using three probes on chromosome 1 and two probes on chromosome 8 to more accurately determine increases in copy number. We found gains of chromosome 1q to 2.9-3.6 copies per cell and on 8q to 4.4 copies per cell.     

Characterization of nonrandom chromosomal gains and losses in multiple myeloma by comparative genomic hybridization

Clonal chromosomal changes in multiple myeloma (MM) and related disorders are not well defined, mainly due to the low in vivo and in vitro mitotic index of plasma cells. This difficulty can be overcome by using comparative genomic hybridization (CGH), a DNA-based technique that gives information about chromosomal copy number changes in tumors. We have performed CGH on 25 cases of MM, 4 cases of monoclonal gammopathy of uncertain significance, and 1 case of Waldenstrom's macroglobulinemia. G-banding analysis of the same group of patients demonstrated clonal chromosomal changes in only 13 (43%), whereas by CGH, the number of cases with clonal chromosomal gains and losses increased to 21 (70%). The most common recurrent changes detected by CGH were gain of chromosome 19 or 19p and complete or partial deletions of chromosome 13. +19, an anomaly that has so far not been detected as primary or recurrent change by G-banding analysis of these tumors, was noted in 2 cases as a unique change. Other recurrent changes included gains of 9q, 11q, 12q, 15q, 17q, and 22q and losses of 6q and 16q. We have been able to narrow the commonly deleted regions on 6q and 13q to bands 6q21 and 13q14-21. Gain of 11q and deletion of 13q, which have previously been associated with poor outcome, can thus be detected by CGH, allowing the use of this technique for prognostic evaluation of patients, without relying on the success of conventional cytogenetic analysis.     

Detection of homonuclear decoupled in vivo proton NMR spectra using constant time chemical shift encoding: CT-PRESS

We revisited the cytogenetic alterations of the cervical adenocarcinoma cell line HeLa through the use of spectral karyotyping (SKY), comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH). SKY analysis unequivocally characterized all abnormal chromosomes. Chromosomal breakpoints were primarily assigned by simultaneous assessment of SKY painted chromosomes and inverted 4,6-diamidino2-phenylindole banding from the same cell. Twenty clonally abnormal chromosomes were found. Comparison with previously reported HeLa G-banding karyotypes revealed a remarkably stable cytogenetic constitution because 18 of 20 markers that were found were present before. The classification of 12 markers was refined in this study. Our assignment of the remaining six markers was consistent with those described in the literature. The CGH map of chromosomal copy number gains and losses strikingly matched the SKY results and was, in a few instances, decisive for assigning breakpoints. The combined use of molecular cytogenetic methods SKY, CGH, and FISH with site-specific probes, in addition to inverted 4,6-diamidino-2-phenylindole or conventional G-banding analysis, provides the means to fully assess the genomic abnormalities in cancer cells. Human papillomaviruses (HPVs) are frequently integrated into the cellular DNA in cervical cancers. We mapped by FISH five HPV18 integration sites: three on normal chromosomes 8 at 8q24 and two on derivative chromosomes, der(5)t(5;22;8)(qll;q11q13;q24) and der(22)t(8; 22)(q24;q13), which have chromosome 8q24 material. An 8q24 copy number increase was detected by CGH. Dual-color FISH with a c-MYC probe mapping to 8q24 revealed colocalization with HPV18 at all integration sites, indicating that dispersion and amplification of the c-MYC gene sequences occurred after and was most likely triggered by the viral insertion at a single integration site. Numerical and structural chromosomal aberrations identified by SKY, genomic imbalances detected by CGH, as well as FISH localization of HPV18 integration at the c-MYC locus in HeLa cells are common and representative for advanced stage cervical cell carcinomas. The HeLa genome has been remarkably stable after years of continuous cultivation; therefore, the genetic alterations detected may have been present in the primary tumor and reflect events that are relevant to the development of cervical cancer.     

Recurrent DNA copy number changes in 1q, 4q, 6q, 9p, 13q, 14q and 22q detected by comparative genomic hybridization in malignant mesothelioma

Comparative genomic hybridization (CGH) analyses were performed on 27 human pleural mesothelioma tumour specimens, consisting of 18 frozen tumours and nine paraffin-embedded tumours, to screen for gains and losses of DNA sequences. Copy number changes were detected in 15 of the 27 specimens with a range from one to eight per specimen. On average, more losses than gains of genetic material were observed. The loss of DNA sequences occurred most commonly in the short arm of chromosome 9 (p21-pter), in 60% of the abnormal specimens. Other losses among the abnormal specimens were frequently detected in the long arms of chromosomes 4 (q31.1-qter, 20%), 6 (q22-q24, 33%), 13 (33%),14 (q24-qter, 33%) and 22 (q13, 20%). A gain in DNA sequences was found in the long arm of chromosome 1 (cen-qter) in 33% of the abnormal specimens. Our analysis is the first genome-wide screening for gains and losses of DNA sequences using comparative genomic hybridization in malignant pleural mesothelioma tumours. The recurrent DNA sequence changes detected in this study suggest that the corresponding chromosomal areas most probably contain genes important for the initiation and progression of mesothelioma.     

Characteristic pattern of chromosomal gains and losses in primary large B-cell lymphomas of the gastrointestinal tract

In contrast to low-grade B-cell lymphomas originating in the gastrointestinal (GI) tract, only few cytogenetic data are available for the large cell, highly malignant variants. We studied 31 large B-cell lymphomas of the GI tract by comparative genomic hybridization (CGH) and fluorescence in situ hybridization using specific DNA probes (FISH). The most frequent aberrations were gains of all or of parts of chromosomes 11 (11 cases), 12 (9 cases), 1q (4 cases), and 3q (4 cases). Losses of parts of chromosome 6q and of parts of the short arm of chromosome 17 (6 cases each) were found most frequently. In four cases a total of seven high-level DNA amplifications was detected. In two of these cases, involvement of specific protooncogenes (REL and MYC) was shown. Some genetic aberrations seemed to be associated with an inferior clinical course: patients with >/=2 aberrations had a significantly shorter median survival. Furthermore, all patients with gains of all or parts of chromosome arm 1q and with high-level DNA amplifications as well as seven of nine patients with gains of all or parts of chromosome 12 died of lymphoma. In conclusion, the pattern of chromosomal gains and losses in large B-cell lymphomas was different from data reported for low-grade (MALT) lymphomas of the stomach and bowel, especially with respect to the high incidence of partial gains of chromosome arm 11q and of all or parts of chromosome 12 and the low frequency of polysomy 3. In addition, our data suggest that chromosomal gains and losses detected by CGH and FISH may predict for the outcome of patients with this tumor entity.     

Allelic losses on chromosomes 14, 10, and 1 in atypical and malignant meningiomas: a genetic model of meningioma progression

To investigate chromosomal events that underlie formation and progression of meningiomas, we have examined a set of 18 benign (WHO grade I), 15 atypical (grade II), and 13 anaplastic/malignant (grade III) meningiomas for loss of heterozygosity (LOH) on chromosomes 1p, 6p, 9q, 10q, and 14q. Frequent loss of loci on these chromosomes was seen in grade II and grade III tumors, specifically, 14q (II and III, 47 and 55%), 1p (40 and 70%), and 10q (27 and 40%). In contrast, LOH for these loci was infrequent in benign meningiomas, specifically, 14q (0%), 1p (11%), and 10q (12%). The smallest common regions of deletion that could be defined were 14q24-q32, 1p32-pter, and 10q24-qter. These observations indicate the likely presence of tumor suppressor genes in these regions that are involved in the development of WHO grade II and grade III meningiomas. Because LOH for loci on chromosomes 1p and 10q was found in tumors of all grades and because the frequency of LOH in all three regions increased with tumor grade, these results would support a model for the formation of aggressive meningiomas through tumor progression.     

Characterization of cogon grass (Imperata cylindrica) pollen extract and preliminary analysis of grass group 1, 4 and 5 homologues using monoclonal antibodies to Phleum pratense

In this study, we investigated whether fluorescein isothiocyanate (FITC)-labeling of test DNA and Texas-red (TR) labeling of reference DNA in comparative genomic hybridization (CGH) experiments cause the results to differ from those obtained using the opposite combination (reverse labeling). Analysis was performed on a total of 20 DNA specimens consisting of 13 frozen bone marrow aspirates from patients with acute myeloid leukemia, and fresh peripheral blood samples from seven healthy donors. For CGH, one aliquot from each test DNA sample was labeled using nick-translation with FITC-dUTP and another with TR-dUTP. Afterwards, the FITC-dUTP and TR-dUTP-labeled test DNAs were hybridized to TR-dUTP- and FITC-dUTP-labeled normal reference DNAs, respectively. The results using the two combinations were compared with each other and with the results of G-banding karyotype analysis. Karyotype data was used to detect artifacts known to occur in some chromosome regions in CGH analysis. The control DNAs labeled with FITC or TR showed no DNA copy number changes. Regardless of the fluorochrome employed for labeling, no DNA copy number changes were detected using CGH in patients with normal karyotypes, nor in patients whose karyotype aberrations were present in less than 40% of cells. In the remaining patients, CGH revealed DNA copy number changes that coincided with the results of the G-banding analysis. Hybridization artifacts known to occur in CGH experiments affecting chromosome regions 1p33-pter, 16p, 17p, 19, and 22 were observed in 15-23% of the tumor samples labeled with FITC, but not in samples labeled with TR. In addition, other previously unreported overrepresentations affecting 7q21, 9q34, 16q, 17q, and chromosome 20 were observed at very low frequencies in up to 10% of the samples when FITC was used to label test DNA. However, when TR was used, overrepresentations were observed at 4q13-q21, 11q21-q23, 13q21-qter, and Xq21-q22, whereas 19p was underrepresented. The results demonstrate that TR-labeling confirms abnormalities detected using FITC-labeling and reduces hybridization artifacts in the known problematic regions of the human genome.     

A similar pattern of chromosomal alterations in prostate cancers from African-Americans and Caucasian Americans

A combination of genetic and epigenetic factors may explain the disproportionate incidence and mortality of prostate cancer among African-American males (AAMs) as compared with Caucasian American males (CAMs). We wished to determine whether primary prostate cancers from AAMs and CAMs harbor different patterns or frequencies of chromosomal alterations. Comparative genomic hybridization (CGH) was performed on clinically localized, untreated primary prostate cancers from 16 AAMs and 16 CAMs. Detailed statistical analysis was used to delineate gains and deletions with high sensitivity and specificity and to compare the frequency and pattern of alterations between the two groups of tumors. The two groups of patients had indistinguishable preoperative serum prostate-specific antigen levels, and the two groups of tumors had similar pathological stages and grades. Chromosomal gains and deletions occurred in regions known to be frequently altered in prostate cancer. Specifically, the most frequent alterations were deletions of regions on chromosomes 13q, 5q, 16q, and 8p and gains of regions on 8q and 5q. When tumors from AAMs and CAMs were compared, the frequencies of alteration (deletion, gain, or no alteration) were similar across 98.9% of the length of the genome. The patterns of alterations of the most frequently altered chromosomes were also similar between tumors from AAMs and CAMs. We concluded that primary prostate cancers from AAMs and CAMs harbor a similar pattern and frequency of chromosomal alterations. These data support the notion that sporadic prostate cancers from AAMs and CAMs develop by similar chromosomal mechanisms. Biological differences, if present, do not occur on the chromosomal level.     

Daxx, a novel Fas-binding protein that activates JNK and apoptosis

We examined 33 primary gastric carcinomas using comparative genomic hybridization to detect changes in the DNA copy number and the chromosomal location of these changes. Ninety-four percent (31 of 33) showed 1 or more DNA copy number changes, such as increases at 2p23-p25 (observed in 21% of the total cases), 3q26.3-q27 (24%), 7p15 (24%), 9p22-pter (18%), and 13q22-q34 (21%) and decreases at 1p34.2-p36.2 (18%) and Y (52%). Histological examination indicated that increases at 3q26.1-q26.3 and 7p15 and decreases at 1p36.1-p36. 2 and Y were commonly observed in both differentiated and undifferentiated types. Increases at 3q27, 6q23-q25, and 7cen-p14 and decreases at 1p34.2-p35 and 17p12 were predominantly observed in the differentiated type, and increases at 2p23-pter, 9p22-pter, and 13q31-qter and a decrease at 6p21.3 were predominantly observed in the undifferentiated type. In addition, clinical staging of tumors showed that increases at 2p23-p25, 7p14-p21, 7q31-q32, and 9p22-pter and a decrease at Y were observed in early-stage tumors, whereas increases at 9q32-q33 and 15q26 were observed only in late-stage tumors. Many of the abnormalities detected in this study were not previously reported in gastric carcinomas. Our comparative genomic hybridization results indicate the presence of genetic alterations that may play some important role in the development and progression of gastric carcinomas.     

Hepatobiliary tuberculosis

Comparative genomic hybridization (CGH) has been proven to be an important tool in interphase cytogenetics of solid tumors. Although, because of methodological implications, balanced aberrations are not detected by CGH, the technique has uncovered a variety of new and interesting imbalanced karyotype changes. However, only a few studies deal with its application to hematologic disorders, although this is a main topic of cytogenetics. The aim of our study was, therefore, to evaluate the usefulness of CGH in the examination of hematologic neoplasms. For this purpose, bone marrow aspirates of 33 patients with different hematologic disorders were examined with CGH and the results compared with conventional cytogenetics (CC) and fluorescence in situ hybridization (FISH). CGH showed chromosome changes in 8 of 33 cases. CC found balanced aberrations in 4 of 33 and unbalanced changes in 9 of 33 samples. Differences between CGH and CC in unbalanced aberrations were seen in four cases. In these samples, either the number of aberrant cells found by CC was low and, therefore, difficult to detect by CGH, or complex aberrations in different cell clones as seen in CC were lumped together as one karyotype by CGH. In one sample, CC was not capable of giving any results at all, whereas CGH showed trisomy 8. CGH was also helpful in defining the bands involved in the structural aberrations, which was difficult by CC in some cases because of the low quality of metaphase spreads. All results obtained by CGH were confirmed by FISH, whereas CC and FISH were discordant in one case. Although CGH was not able to detect all aberrations, it gave important additional information for the correct localization of the aberrations found in CC, and it was most helpful in samples not processed successfully in CC. These advantages would open up a new field of application for CGH not only for research, but also for diagnostic purposes.     

The new toothpastes

Total genomic DNA sampled from 20 oral squamous cell carcinomas (SCCs) and from four SCC cell lines, was examined for genomic imbalances using comparative genomic hybridisation (CGH). Gains and losses of DNA copy number aberrations (CNAs) were found in the primary tumours, but also in the cell lines at a varying number. The patterns of CNAs proved to be rather peculiar in oral SCCs, gains of genetic material clearly dominating compared with losses, and a rather high uniformity of these patterns was an impressive finding. Hypersomies of whole chromosomes, e.g. numbers 17 and 19 or of whole chromosome arms, e.g. 20q, were particularly evident. The segments most frequently gained in oral SCCs were 3q26-q27, 5p15 and 9q34 (16 of 20 tumours each), as well as 1p36.3, 8q24, 10q26, 19 and 20q (15/20 each). Among the 15 tumours with more than 10 CNAs, all showed these imbalances. 11q13 was a band often involved in increases (14/20 tumours), but in several tumours was involved in amplification of DNA copy number. Several other chromosomal segments over represented in more than 60% of the tumours, as, for example, 12q24, 15q22-q24, 16p13.2 and 17q (14/20 tumours each), 6q26-qter, 7p22, 12p12.2-p13, 14q31-q32.2 (13/20) and 1q32-q41, 2q37, 16q23-q24 (12/20 each). In contrast, loss of material affected only a few chromosomal segments, as, for example, 3p12 (12 of the 20 tumours), 5q21 (10/20), 6q13 (8/20). The peculiarities of these findings, in some respect, differ from those found in other epithelial tumours, suggesting a high impact of environmental factors in the generation and progression of these tumours.     

Granulins: the structure and function of an emerging family of growth factors

BACKGROUND: Comparative genomic hybridization (CGH) was performed on 50 primary head and neck squamous cell carcinomas (HNSCC) to discover molecular genetic alterations underlying the progression of these tumors. METHODS: In CGH, equal amounts of differently labeled tumor deoxyribonucleic acid (DNA) and normal reference DNA were hybridized simultaneously to normal metaphase chromosomes. They were visualized by different fluorochromes, and the signal intensities were quantitated separately as gray levels along the single chromosomes. The over- and underrepresented DNA segments were determined by computation of ratio images and average ratio profiles. RESULTS: Prevalent changes observed in more than 50% of the HNSCC included deletions of chromosomes 1p, 4, 5q, 6q, 8p, 9p, 11, 13q, 18q, and 21q and DNA overrepresentations of 11q13 as well as 3q, 8q, 16p, 17q, 19, 20q, and 22q. The calculation of ratio profiles of tumor subgroups revealed that well differentiated carcinomas (G1) were defined by the deletions of chromosomes 3p, 5q, and 9p together with the overrepresentation of 3q, suggesting the association with early tumor development. Accordingly, the undifferentiated tumors (G3) were characterized by additional deletions of chromosomes 4q, 8p, 11q, 13q, 18q, 21q, and overrepresentations of 1p, 11q13, 19, and 22q. CONCLUSION: Our data indicate that the CGH patterns of chromosomal imbalances may help to define the malignant potential of head and neck squamous cell carcinomas.     

Accumulation of genetic changes is associated with poor prognosis in grade II astrocytomas

Unexpectedly aggressive clinical course of some grade II astrocytomas is a diagnostic dilemma for routine histopathology. Because increasing tumor malignancy is a consequence of progressive accumulation of chromosomal alterations, we investigated whether aggressive behavior of grade II astrocytomas could be predicted by the number and type of gross chromosomal aberrations. We used comparative genomic hybridization to analyze 11 grade II astrocytomas with typical (good, n = 7) or poor (n = 4) prognosis. The results were also compared with a reference material of 13 grade III-IV astrocytomas and nine established cell lines. We found a median of two aberrations (range 0 to 4) in tumors with good prognosis and of 15.5 changes (range 8 to 28) in tumors with poor prognosis. Chromosomal gains were present in both groups, whereas chromosomal losses were frequent in tumors with poor prognosis (median 9.5, range 3 to 14) but rare in tumors with good prognosis (range 0 to 2). All chromosomal gains were also found in the high-grade astrocytoma group and the majority of them in cell lines. Chromosomal losses in grade II astrocytomas with poor prognosis were very similar to those in grade III-IV astrocytomas and cell lines. We conclude that an early accumulation of genetic changes in grade II astrocytomas is closely associated with poor patient prognosis, suggesting diagnostic use for comparative genomic hybridization in characterization of grade II astrocytomas.     

FISH, interphase cytogenetics, gene rearrangements]

OBJECTIVE: To investigate the possible involvement of chromosome abnormalities in pathogenesis of human esophageal cancer. METHODS: Four cell lines of human esophageal cancer (EC) established in our laboratory were analysed using interphase fluorescence in situ hybridization (FISH), chromosome painting technique and comparative genomic hybridization (CGH). RESULTS: Chromosome gain of 1,2,3,8,16, 17, and 20 was found in the four cell lines, and loss of chromosome Y in cell line EC8712, EC8733 and EC8501 was noted. Other frequent changes were partial deletion of 1p, translocation of 2q and amplification of 5p in all 4 cell lines, and amplification of 8q and 13q in EC8733 and deletion of 17p in EC8712. CONCLUSION: The data suggest that nonrandom chromosome aberrations may play an important role in the pathogenesis of human esophageal cancer.     

Mapping of chromosomal imbalances in pancreatic carcinoma by comparative genomic hybridization

To identify recurrent chromosomal imbalances in pancreatic adenocarcinoma, 27 tumors were analyzed by using comparative genomic hybridization. In 23 cases chromosomal imbalances were found. Gains of chromosomal material were much more frequent than losses. The most common overrepresentations were observed on chromosomes 16p (eight cases), 20q (seven cases), 22q (six cases), and 17q (five cases) and under-representations on a subregion of chromosome 9p (eight cases). Distinct high-level amplifications were found on 1p32-p34, 6q24, 7q22, 12p13, and 22q. These data provide evidence for a number of new cytogenetically defined recurrent aberrations which are characteristic of pancreatic carcinoma. The overrepresented or underrepresented chromosomal regions represent candidate regions for potential oncogenes and tumor suppressor genes, respectively, possibly involved in pancreatic tumorigenesis.     

Comparative genomic hybridization and loss of heterozygosity analyses identify a common region of deletion at 15q11.1-15 in human malignant mesothelioma

Comparative genomic hybridization analysis was performed to identify chromosomal imbalances in 24 human malignant mesothelioma (MM) cell lines derived from untreated primary tumors. Chromosomal losses accounted for the majority of genomic imbalances. The most frequent underrepresented segments were 22q (58%) and 15q1.1-21 (54%); other recurrent sites of chromosomal loss included 1p12-22 (42%), 13q12-14 (42%), 14q24-qter (42%), 6q25-qter (38%), and 9p21 (38%). The most commonly overrepresented segment was 5p (54%). DNA sequence amplification at 3p12-13 was observed in two cases. Whereas some of the regions of copy number decreases (i.e., segments in 1p, 6q, 9p, and 22q) have previously been shown to be common sites of karyotypic and allelic loss in MM, our comparative genomic hybridization analyses identified a new recurrent site of chromosomal loss within 15q in this malignancy. To more precisely map the region of 15q deletion, loss of heterozygosity analyses were performed with a panel of polymorphic microsatellite markers distributed along 15q, which defined a minimal region of chromosomal loss at 15q11.1-15. The identification of frequent losses of a discrete segment in 15q suggests that this region harbors a putative tumor suppressor gene whose loss/inactivation may contribute to the pathogenesis of many MMs.     

Chromosomal gains and losses in uveal melanomas detected by comparative genomic hybridization

Eleven uveal melanomas were analyzed using comparative genomic hybridization (CGH). The most abundant genetic changes were loss of chromosome 3, overrepresentation of 6p, loss of 6q, and multiplication of 8q. The smallest overrepresented regions on 6p and 8q were 6pter-->p21 and 8q24-->qter, respectively. Several additional gains and losses of chromosome segments were repeatedly observed, the most frequent one being loss of 9p (three cases). Monosomy 3 appeared to be a marker for ciliary body involvement. CGH data were compared with the results of chromosome banding. Some alterations, e.g., gains of 6p and losses of 6q, were observed with higher frequencies after CGH, while others, e.g., 9p deletions, were detected only by CGH. The data suggest some similarities of cytogenetic alterations between cutaneous and uveal melanoma. In particular, the 9p deletions are of interest due to recent reports about the location of a putative tumor-suppressor gene for cutaneous malignant melanoma in this region.