Cytogenetic study of a testicular tumor in a translocation (13;14) carrier

Characterization of 9q;15q whole-arm translocation derivatives in non-small cell lung carcinomas by fluorescence in situ hybridization

We report derivative chromosomes, originally interpreted as 9q;15q whole-arm translocations, in tumor cells from two patients with non-small cell lung cancer (NSCLC). One of the tumors was diagnosed as an adenocarcinoma and the other as an adenosquamous carcinoma. In each case, there was no normal chromosome 9. Because of the pericentromeric location of the breakpoints, classical cytogenetic banding techniques did not permit determination of the centromeric origin of these derivative chromosomes. Fluorescence in situ hybridization (FISH) with satellite (alpha, beta, classical), ribosomal DNA, alpha-interferon (alpha-IFN), and whole chromosome painting probes indicated that the 9;15 rearrangement is dicentric in both tumors. In one of these cases, the derivative chromosome is interpreted as a dic(9;15) (p11;p11.2); the other case has a more complicated rearrangement involving reorientation of pericentromeric sequences. A 9q;15q whole-arm derivative chromosome was reported previously in another lung adenocarcinoma, suggesting that this abnormality may represent a recurrent change in lung carcinomas, particularly those displaying adenomatous features.

Cytogenetic studies in patients with gastric cancer

Banded cytogenetic studies of gastric carcinoma are still relatively scarce, comprised of only a small number of patients. This study was performed on peripheral blood lymphocytes and malignant cells of 16 patients with gastric carcinoma. The lymphocytes were analyzed by standard techniques. All patients had a normal constitutional karyotype; 90% of the patients presented an increased breakage rate and nonrandom chromosomal instability mainly in the heterochromatic regions of chromosomes 1, 9, and 16. Decreased response to phytohemagglutinin was observed in 6 (38%) patients. The tissue specimens were analyzed using direct techniques. Normal ploidy was observed in only one patient, 3 tumors were near-diploid, 4 hyperdiploid, 4 near-triploid, and 4 near-tetraploid. Those with the near-triploid or near-tetraploid constitution were in a more advanced pathological stage, most of them with a more complex cytogenetic profile. Particular involvement was found for chromosomes 1 to 4, 7 to 9, 17, and 20, but the more specific nonrandom changes seemed to involve chromosomes 7, 8, 9, and 17.

Numerical chromosome changes in 165 malignant tumors. Evidence for a nonrandom distribution of normal chromosomes

The numbers of normal copies of each of the chromosomes in representative karyotypes from 165 malignant tumors of the bladder, breast, cervix, colorectum, and testis studied in this laboratory or described in the literature were assessed to determine whether particular chromosomes were over- or underrepresented. For each chromosome, the mean number of copies was expressed as a percentage of the number expected on the basis of the total number of chromosomes in the karyotypes. The most highly represented autosomes in the tumors as a whole were, in descending order of frequency, numbers 7, 20, 12, 19, 21, and 3, while those most underrepresented were numbers 10, 1, 4, 5, 14, 17, 11, and 18. In tumors of males, the Y tended to be underrepresented. The X was highly represented in the testicular tumors (there were usually two or more copies) and in colorectal tumors of males, but not in the other tumor categories studied. For the tumors as a whole, statistically significant differences could be demonstrated between pairs of autosomes that were at opposite ends of the frequency range. Differences between tumors at the different sites studied were not demonstrable. It is suggested that the determination of the number of normal copies of chromosomes, i.e., whether there are more or fewer than expected, may usefully complement observations on structural changes by reflecting the presence of oncogenes and tumor-suppressor genes, respectively. It may also point to chromosomes that are involved in significant genic changes in which cytogenetic observations on structural changes are equivocal.

Absence of isochromosome 12p in a pineal region malignant germ cell tumor

We report the first cytogenetic investigation of a rare pineal region mixed germ cell tumor. The mean modal number was 78. Multiple numerical and structural abnormalities were noted. Chromosomes 21 and 1q were consistently overrepresented, and chromosome 13 was underrepresented. A translocation involving chromosome 11 occurred in all metaphases examined. The Y chromosome was lost, and three copies of the X chromosome were present. No isochromosome 12p was identified, but four copies of chromosome 12 were present.

Pathogenesis of adult testicular germ cell tumors. A cytogenetic model

In essence, two models exist of the pathogenetic relationship between seminomas and nonseminomatous germ cell tumors (NSGCTs). In the first model, the histogenesis of seminomas is assumed to diverge from that of the other testicular germ cell tumors (TGCTs) at an early stage. The neoplastic pathway of seminomas and NSGCTs is different, with limited or no crossover. The second model suggests that seminomas and NSGCTs have a common origin with a single neoplastic pathway on which seminomas are an intermediate stage in development of NSGCTs. Our data on the cytogenetics and ploidy of seminomas, combined tumors, and NSGCTs lend support to the model of pathogenesis of seminomas and NSGCTs in which all TGCTs (with the possible exception of spermatocytic seminoma and infantile yolk sac tumor) have a single origin and neoplastic pathway, with seminomas representing an intermediate stage in development of NSGCT components, as opposed to the model in which seminomas and NSGCTs develop separately. The progression of TGCTs probably proceeds from high to lower numbers of chromosomes and is therefore accompanied by a net loss of chromosomal material. This decrease will be the end result of loss of specific chromosomes, gain of some other chromosomes (or part of chromosomes), and development of structural abnormalities.

i(12p)-negative testicular germ cell tumors. A different group?

Cytogenetic analysis was performed of three seminomas, two primary nonseminomas, and two mature residual teratomas following chemotherapy, all lacking i(12p). Testicular germ cell tumors without an i(12p) may represent a subgroup of germ cell tumors, also in their clinical course, compared with those having i(12p).