Unrelated clonal chromosomal aberrations in carcinomas of the oral cavity

Short-term cultures from 12 oral squamous cell carcinomas were cytogenetically investigated. A normal karyotype was found in 3 tumors, 2 of which had many nonclonal changes. Clonal chromosome abnormalities were detected in the remaining 9 cases, in 6 of them in the form of 2 or 3 abnormal clones. In 5 cases the different clones were cytogenetically unrelated, suggesting a multiclonal origin. Numerous additional nonclonal changes were present in 4 of the 9 tumors with clonal aberrations. None of the structural aberrations, clonal or nonclonal, were found in more than one case; nor did any of the rearrangements correspond to cancer-associated aberrations known from other tumors. The aberration breakpoints of the present series and of previously reported tongue cancer clustered to bands 1p32, 1p22, 1p11, 1q21, 1q23, 1q25, 1q32, 1q42, 1q44, 2q31, 3p11, 4q35, 7p22, 11p15, 11q13, 12q24, and 17q25.     

Clonal structural chromosome aberrations in nonneoplastic cells of the skin and upper aerodigestive tract.

Cytogenetic analyses of tumors of the skin and upper aerodigestive tract have repeatedly revealed small, pseudodiploid clones characterized by balanced structural rearrangements and a high frequency of cells with nonclonal structural aberrations. However, the lack of common cytogenetic denominators within the different histologic subtypes, the discrepancy between cytogenetic findings and data obtained from flow cytometric DNA content studies, and the occasional identification of tumors with massively rearranged karyotypes indicate that the chromosome rearrangements present in pseudodiploid cells have little to do with the tumorigenesis or progression. Further support for this conclusion, and indirect evidence that the pseudolipid clones probably do not represent the tumor cell populations, derives from the present study in which clonal and nonclonal structural rearrangements were also found in short-term cultures from nonneoplastic skin and pharyngeal mucosa. It is possible that the aberrations are present in subepithelial fibroblast that have accumulated DNA damage due to extensive exposure to potentially carcinogenic agents.     

Karyotypic findings in tumors of the vulva and vagina.

Neoplasms of the vulva and vagina together account for less than 5% of all female genital tract cancers, and very few cases have been analyzed using chromosome banding techniques. We report the karyotypic findings in a consecutive series of ten tumors of the vulva and vagina; in addition to five squamous cell carcinomas of the vulva, we present the first cytogenetic analysis of two malignant melanomas and a Paget disease of the vulva, as well as an adenocarcinoma and a squamous cell hyperplasia of the vagina. Whereas no clonal karyotypic changes were found in the squamous cell hyperplasia of the vagina, the remaining nine malignant tumors showed clonal chromosome abnormalities. An inverse correlation was found between the degree of histologic differentiation and karyotypic complexity in the squamous cell carcinomas of the vulva. The malignant melanomas had chromosomal aberrations that have previously been described in malignant melanomas occurring elsewhere, but were less karyotypically complex. Cytogenetically unrelated clones were detected in the Paget disease of the vulva but not in any of the other tumors; this finding is consonant with the interpretation that at least a proportion of Paget disease of the vulva arises multicentrically within the epidermis from pluripotent stem cells.     

Cytogenetic instability, predominantly involving chromosome 1, is characteristic of elastofibroma

Elastofibroma, an unusual pseudotumor composed of excessive collagen and abnormal elastic fibers, has rarely been subjected to cytogenetic analysis. Only two cases have been previously defined, both of which demonstrated nonclonal abnormalities. In the present study, three cases of elastofibroma were cytogenetically analyzed. Abnormalities of the short arm of chromosome 1 were seen in all three cases (either clonally or as the most frequently involved region among nonclonal aberrations). In addition, a translocation involving chromosomes 8 and 12 was detected as a clonal rearrangement in one of the three cases. The observation of clonal abnormalities in elastofibroma suggests that this lesion may represent a neoplastic rather than a reactive process.     

Cytogenetics of primary prostatic adenocarcinoma. Clonality and chromosome instability.

We have examined 62 prostatic adenocarcinomas by conventional cytogenetic analysis. Most were primary cultures harvested in 14 days or less. The most consistent finding was a normal male diploid karyotype, found in 87% of all cells analyzed, and as the exclusive finding in 19 tumors. Nonrandom chromosomal changes included gain of chromosome 7 and loss of the Y chromosome. In addition, clonal gains of chromosomes 8, 12, and 18, and clonal losses of chromosomes 14 and 19 were noted in individual cases. Two structural clonal aberrations, a 9p+ in one case and a t(Y;22) (q11.2;p12) in another, were also seen. Ten of 62 cultures demonstrated chromosome instability, defined herein as nonclonal gain or loss of chromosomes in more than 10% of the metaphases examined from that culture. In those cases with nonclonal numerical aberrations, loss of chromosomes was more common than gain. The distribution of apparently random numeric abnormalities was similar to that of the clonal abnormalities in that the most frequent nonclonal gain was of chromosome 7 and the most frequent nonclonal loss was of the Y chromosome. Apparently random structural aberrations were observed in less than 1% of all analyzed cells. These included a 4p-,del(3)(q13), and t(1;11). The extent of apparently random aneuploidy suggests that chromosome instability characterizes cultured prostatic adenocarcinomas. An increase in the frequency of nonclonal aberrations may be an indicator of tumor origin in a predominantly diploid cell population. The coexistence of clonally aberrant, nonclonally aberrant, and normal diploid cells in culture may reflect heterogeneity of prostate tumors in vivo.     

Chromosomal abnormalities in giant cell tumors of bone.

Cytogenetic analysis of short-term cultures from ten giant cell tumors of bone revealed clonal and nonclonal chromosome abnormalities in three tumors and nonclonal changes only in seven. None of the clonal aberrations, inv(21)(p11q21) in one tumor, +5 in another, and t(15q22q), dic(4;22)(p16;p1?), double minutes, dicentrics, and ring chromosomes present in three separate clones in the third tumor, were identical to previously reported clonal changes in giant cell tumors. Telomeric associations were found in five tumors. The telomeres of chromosome arms 19q and 15p were particularly frequently involved.     

Chromosome analysis of 97 primary breast carcinomas: Identification of eight karyotypic subgroups

Chromosome banding analysis of 97 short-term cultured primary breast carcinomas revealed clonal aberrations in 79 tumors, whereas 18 were karyotypically normal. In 34 of the 79 tumors with abnormalities, two to eight clones per case were detected; unrelated clones were present in 27 (34%) cases, whereas only related clones were found in seven. These findings indicate that a substantial proportion of breast carcinomas are of polyclonal origin. Altogether eight abnormalities were repeatedly identified both as sole chromosomal anomalies and as part of more complex karyotypes: the structural rearrangements i(1)(q10), der(1;16)(q10;p10), del(1)(q11–12), del(3)(p12–13p14–21), and del(6)(q21–22) and the numerical aberrations +7, +18, and +20. At least one of these changes was found in 41 (52%) of the karyotypically abnormal tumors. They identify a minimum number of cytogenetic subgroups in breast cancer and are likely to represent primary chromosome anomalies in this type of neoplasia. Other candidates for such a role are translocations of 3p12–13 and 4q21 with various partner chromosomes and inversions of chromosome 7, which also were seen repeatedly. Additional chromosomal aberrations that give the impression of occurring nonrandomly in breast carcinomas include structural rearrangements leading to partial monosomies for 1p, 8p, 11p, 11q, 15p, 17p, 19p, and 19q and losses of one copy of chromosomes X, 8, 9, 13, 14, 17, and 22. The latter changes were seen consistently only in complex karyotypes, however, and we therefore interpret them as being secondary anomalies acquired during clonal evolution.     

Massive cytogenetic heterogeneity in a pancreatic carcinoma: Fifty-four karyotypically unrelated clones

Chromosome analysis after short-term culture revealed remarkable cytogenetic heterogeneity in a pancreatic carcinoma. The patient had no prior history of radio- or chemotherapy. A total of 54 aberrant, near-diploid, karyotypically unrelated clones were identified, three of which displayed clonal evolution. The abnormalities were unbalanced in 30% of the clones. From one to eight karyotypic anomalies per clone were found. Numerical changes were rare, whereas structural aberrations were numerous and diverse and included deletions, duplication, insertions, inversions, translocations, ring formation, and telomeric associations. All chromosomes except No. 15 were involved in structural rearrangements, chromosomes 1, 6, 7, 8, 11, and 12 being the most frequently affected. A similarly massive cytogenetic polyclonality has never been reported previously. Although the spectrum of epithelial neoplasms characterized by karyotypically unrelated clones is increasing, the pathogenetic role of this type of cytogenetic intratumor heterogeneity remains unknown.     

Cytogenetic characterization of a colon adenocarcinoma from a familial polyposis coli patient

We report on the cytogenetic findings in a fresh biopsy of a colorectal adenocarcinoma in a patient with familial polyposis coli (FAP). The stemline had 45 chromosomes with several clonal chromosome aberrations including a der(17)t(17;?), and -18, which are the two most recurrent aberrations in sporadic colorectal carcinomas. This finding is discussed in relation to the chromosomal changes described in sporadic colorectal carcinomas and in FAP cell lines.     

Chromosomal instability and marker chromosome evolution in oral squamous cell carcinoma

Squamous cell carcinoma of the head and neck and its subset, oral squamous cell carcinoma (OSCC), arise through a multistep process of genetic alterations as a result of exposure to environmental agents, such as tobacco smoke, alcoholic beverages, and viruses, including human papillomavirus. We and others have shown that the karyotypes of OSCC are near-triploid and contain multiple structural and numerical abnormalities. However, despite a background of clonal chromosomal aberrations, individual cells within a culture express many nonclonal numerical and structural abnormalities, termed chromosomal instability (CIN). To evaluate CIN in oral cancer cells, we isolated clones from two OSCC cell lines and carried out classical cytogenetic analysis, fluorescence in situ hybridization using centromere-specific probes, and spectral karyotyping. We observed variation in chromosome number within clones and between clones of the same cell line. Although similar numbers of centromeric signals for a particular chromosome were present, "homologs" of a chromosome varied structurally from cell to cell (marker chromosome evolution) as documented by classical and spectral karyotyping. In addition to the numerical chromosome variations within a clone, we observed marker chromosome evolution by structural chromosome alterations. It appears that both intrinsic structural alterations and extrinsic cytoskeletal factors influence chromosome segregation, resulting in individual tumor cells that express unique karyotypes. We show that CIN and marker chromosome evolution are essential acquired features of neoplastic cells. Proliferation of this heterogeneous cell population may provide some cells with the ability to evade standard therapies.     

Ovarian granulosa-stromal cell tumors are characterized by trisomy 12.

Eleven ovarian granulosa-stromal cell tumors including 1 thecoma, 2 fibromas, 6 fibrothecomas, and 2 granulosa cell tumors, were karyotyped after direct harvest and/or short-term tissue culture. Bilateral fibrothecomas from one patient appeared to lack cytogenetic aberrations: the remaining nine tumors were characterized by trisomy for chromosome 12. Cytogenetic aberrations in the two granulosa cell tumors were much less complex than those described previously in undifferentiated carcinomas; accordingly cytogenetic analyses might be useful in distinguishing these categories. The consistent occurrence of trisomy 12 in different varieties of granulosa-stromal cell tumors suggests a common mechanism of oncogenesis within this diverse group of neoplasms. That mechanism probably involves promotion of low-grade, orderly cell proliferation.     

Nonrandom karyotypic features in squamous cell carcinomas of the skin.

We report the finding of clonal chromosome abnormalities in 13 short-term cultured squamous cell carcinomas (SCCs) of the skin. Intratumor heterogeneity, in the form of cytogenetically related (subclones) or unrelated clones, was detected in six tumors. Whereas clones with complex karyotypic changes were found in 6 tumors, clones with simple anomalies were observed in 10 tumors, and sometimes these clones coexisted with highly abnormal clones. Rearrangement of chromosome 8, in the form of isochromosome i(8q) or whole arm translocation, was the most common aberration, found predominantly in complex clones. Another recurrent feature, i.e., the centromeric rearrangement of chromosome 1, as isochromosome i(1q) or i(1p), or whole arm translocations, was always part of a complex karyotype. Homogeneously staining regions were found in two cases, one with a highly complex karyotype and the other with a simple karyotype. In order to obtain an overall karyotypic picture in SCC of the skin, the cytogenetic findings in 10 SCCs reported earlier were reviewed. The chromosomes most commonly affected were, in decreasing order, chromosomes 1, 11, 8, 9, 5, 3, and 7. Chromosomal sites most frequently rearranged were almost all pericentromeric: they were 8q10-q11, 1p10-q12, 5p10-q11, 11p15, and 9p10-q10. Recurrent anomalies were i(1q), i(8q), i(5p), i(1p), i(9p), and i(9q). Among them, only i(8q) and i(9q) might be assumed to be early genetic events, considering the fact that they could occasionally be identified in simple clones. The most frequent losses included part of or the entire chromosomes 2, 4, 9, 11, 14, 18, and 21, arm 8p, and chromosomes X, Y, and 13. Overrepresentation most frequently involved 1q, chromosome 7, and 8q. The characteristic karyotypic pattern observed in skin SCC was in line with the experience in several other carcinomas. Genes Chromosomes Cancer 26:295-303, 1999.     

Clonal chromosome abnormalities in premalignant lesions of the skin

Two lesions, actinic keratosis (AK) and squamous cell carcinoma in situ (CIS), are believed to be precursors of squamous cell carcinoma (SCC) of the skin. These lesions can serve as an excellent model system for studying genetic changes associated with the inception of skin SCC. In the present study, five such lesions of the skin, three AKs and two AK+CIS, from three patients were short-term cultured and analyzed cytogenetically. One of the patients (case 3) had also an SCC in addition to three premalignant lesions. All lesions, but one, showed clonal karyotypic abnormalities. The recurrent changes identified were numerical, that is, +7 and +20. The structural rearrangements found in three AK were different, but it could be noted that the distal part of the long arm of chromosome 4 was involved in two AK and the SCC of case 3A. It was also interesting that chromosome 1 participated in structural rearrangements in three AK with band 1p31 being involved in two tumors. The karyotypic profile of these lesions is compared with that of skin SCC; it turns out that the general patterns are different in the sense that the SCC more often have complex karyotypes and display unbalanced aberrations involving the centromeric regions. Some karyotypic similarities between the SCC and their precursors are revealed. The fact that the structural rearrangements involving chromosomal band 3p13 and the centromeric region of chromosome 3 in AK are common features for many types of malignant tumors, including skin SCC, indicates that these changes are early genetic events associated with malignant transformation.     

Chromosome analysis of 20 breast carcinomas: Cytogenetic multiclonality and karyotypic-pathologic correlations

Short-term cultures from 20 breast carcinomas were analyzed cytogenetically. A normal female chromosome complement was found in 4 cases. Clonal chromosome aberrations were detected in 16 tumors. In 10 tumors, multiple cytogenetic clones were found; in 2 cancers the clones were related, reflecting clonal evolution, but in the remaining 8 tumors the clones were cytogenetically unrelated, indicating clonal heterogeneity in the origin of the tumor parenchyma. Correlation analysis between karyotypic and pathologic parameters indicated that cases with complex karyotypes and/or cytogenetically unrelated clones, when compared with cases with a single simple karyotypic abnormality, were generally of higher histologic malignancy grade, had more mitoses in the histologic sections, and also more often had carcinoma in situ lesions in the same breast. © 1993 Wiley-Liss, Inc.     

Barrett's adenocarcinomas resemble adenocarcinomas of the gastric cardia in terms of chromosomal copy number changes,but relate to squamous cell carcinomas of the distal oesophagus with respect to the presence of high-level amplifications

Three different cancers predominantly occur at the gastro-oesophageal junction: squamous cell carcinomas of the distal oesophagus, adenocarcinomas of the distal oesophagus (Barrett's carcinomas), and adenocarcinomas of the gastric cardia. The aim of the present study was to investigate how, and to what extent, Barrett's carcinoma differs from adenocarcinoma of the gastric cardia on the one hand and squamous cell carcinoma of the distal oesophagus on the other, with respect to chromosomal aberrations and related gene expression. The present study analysed 14 squamous cell carcinomas, 24 Barrett's carcinomas, and 16 carcinomas of the gastric cardia. Comparative genomic hybridization revealed chromosomal abnormalities in all cases. Typical chromosomal aberrations for the squamous cell carcinoma type were gains at 3q and 11q13, and losses at 3p, 4q, 9p, 11q, and 13q. In contrast, typical copy number changes for both cardiac and Barrett's adenocarcinomas were gains at 2q, 7p, and 13q, and losses at 17p. High-level amplification occurred in all three groups, but its frequency in the cardiac carcinomas was lower than in the other two groups. In conclusion, squamous cell carcinomas are characterized by chromosomal aberrations which are distinct from those seen in carcinomas of the gastric cardia and in Barrett's adenocarcinomas. With respect to Barrett's cancer, the chromosomal aberrations more closely reflect the adenocarcinoma phenotype than the squamous origin of the epithelium.     

Statistical analyses of karyotypic complexity in head and neck squamous cell carcinoma

More than 250 head and neck squamous cell carcinomas (HNSCCs) with clonal chromosomal abnormalities have been reported. Even though the pattern of aberrations is nonrandom, no specific primary or secondary karyotypic abnormalities have been identified. One explanation for the still-rudimentary understanding of the cytogenetic evolution in HNSCC could be the pronounced karyotypic complexity seen in these tumors. In an attempt to overcome this difficulty, we have applied several statistical methods such as hierarchical cluster analysis, multidimensional scaling, and k-means clustering, which allow the identification and interpretation of karyotypic pathways, as well as establishing a temporal order of chromosomal imbalances on 241 published and 70 previously unpublished HNSCC karyotypes. From the analysis of the distribution of the number of imbalances per tumor we suggest that the carcinomas evolve through three phases representing different stages of chromosomal instability. Two major cytogenetic pathways, one dominated by gains and another by losses, were identified by means of principal component analysis. These were initiated by +7 and by any of the aberrations 1p-, 3p-, or 7q-, respectively.     

Interstitial deletion of the short arm of chromosome 3 as a primary chromosome abnormality in carcinomas of the breast

Interstitial deletions of the short arm of chromosome 3 were found in short-term cultures of five breast carcinomas (of 41 breast cancers with clonal aberrations analyzed by us during the same period). They were the only clonal structural change in three tumors; in the remaining two, the clone with 3p– coexisted with seemingly unrelated clones that had other structural and numerical aberrations. The deletions were identical, del(3)(p12p14), in four cases. The fifth tumor seemed to have a smaller deletion, interpreted as del(3)(p13p14). Our findings constitute karyotypic evidence that 3p deletions are relatively common in breast carcinomas and concur with the molecular genetic detection of loss of heterozygosity in this chromosome arm. The fact that the deletions were found as solitary changes indicates that loss of genetic information from 3p loci is an early, possibly primary, event in tumorigenesis. © 1993 Wiley-Liss, Inc.     

Do random (non-clonal) chromosome abnormalities in bone marrow predict a clone to come? Southwestern Oncology Group of Leukemia Cytogenetics Subcommittee

The biologic significance of clonal karyotypic abnormalities in human neoplasms is becoming better understood, but the significance of rare chromosomal aberrations is uncertain. Useful, yet arbitrary, cytogenetic definitions of a clone have been established and cases with a frequency of chromosome aberrations less than the accepted convention are explained by random loss, karyotypic instability/evolution, or other technical artifact. Are non-clonal chromosomal abnormalities that may predict future clinically significant clones being ignored? A brief case report is presented raising two such issues in the same myelodysplastic patient. This child had monosomy 7 and, later, trisomy 8, as well as increased numerical/structural aberrations seeming to predict relapse. Preliminary data from the Southwestern Oncology group is also presented. Non-clonal data should be included, when appropriate, in the clinical report.     

Genomic defects in nonfamilial renal cell carcinoma. Possible specific chromosome change

Using a newly developed combined method of enzymatic technique and short-term tissue culture, 30 tumor specimens from 26 patients with nonfamilial renal cell carcinoma were subjected to cytogenetic analysis. Of the 26 patients, 19 had chromosomally abnormal tumors, four (including two oncocytomas) were normal, and three did not grow. The modal chromosome numbers ranged from 44 to 98 (including two pseudotetraploids). Banding analysis revealed 38 clonal aberrations and ten nonclonal aberrations. Abnormalities were of structure and number. The most consistent clonal abnormality was a trisomy or tetrasomy chromosome 7 occurring in tumors from 15 of the 19 patients with cytogenetically abnormal tumors. In four cases, trisomy 7 was the only visible abnormality observed, and in an additional five it was the only abnormality in two or more cells. An abnormal chromosome 3 was found in ten (38%) of the cases. Two were trisomic for #3, two were monosomic, three were hyperdiploid, and three had interstitial deletions with breakpoints clustered from p11 to p25. In only one case was a deleted #3 the only abnormality observed in a clone of cells. Loss of the sex chromosome was seen in eight (35%) of the 23 chromosomally abnormal cases including all four (100%) patients with bilateral disease. One of the patients with bilateral disease had an abnormal clone with monosomy X as the only abnormality. These data suggest that trisomy or tetrasomy 7 more often represents the specific primary abnormality than abnormalities of either chromosome 3 or the sex chromosomes. From this, a model of chromosomal progression may be constructed for nonfamilial renal cell carcinoma, which could assist in pathologic classification and prognostic and therapeutic considerations.