Trisomy 10 in renal cell carcinoma

Dissecting karyotypic patterns in renal cell carcinoma: an analysis of the accumulated cytogenetic data

Renal cell carcinoma (RCC) is one of the most frequent malignancies in Western societies. The most common subtypes are conventional (clear-cell) and papillary carcinomas, which account for about 75 and 10% of cases, respectively. Cytogenetically, conventional RCC is the best-studied subtype and is characterized by chromosomal losses: loss of the short arm of chromosome 3 being the most common. Papillary tumors frequently show gains of chromosomes 7 and 17, and the more progressed forms have, in addition, gains of chromosomes 16, 12, and 20. In the present investigation we used 796 RCC karyotypes to identify the most frequent genomic imbalances. Tumor cases were then classified with respect to the presence or absence of these imbalances and statistically analyzed to assess the order of appearance of chromosomal imbalances, as well as possible karyotypic pathways and cytogenetic subtypes. We established a temporal order by which the different imbalances occur and showed that at least two cytogenetic pathways exist in RCC, one hypodiploid characterized by presence of 3p- and one hyperdiploid characterized by the presence of +7. The data suggest that conventional-type tumors predominantly evolve through the hypodiploid pathway but that an alternative route may be by hyperdiploidy if 3p- is present. Tumors with a papillary growth pattern predominantly progress through the hyperdiploid pathway. The analyses also revealed three possible cytogenetic subtypes of the papillary tumors, one characterized by the presence of +10, a second by +17 and +3q, and a third by +16, +20, and +12.

RET rearrangements in papillary thyroid carcinomas and adenomas detected by interphase FISH

Activation of the RET protooncogene through somatic rearrangements represents the most common genetic alteration in papillary thyroid carcinoma (PTC). Three main rearranged forms of RET have been described: RET/PTC1 and RET/PTC3, which arise from a paracentric inversion of the long arm of chromosome 10, and RET/PTC2, which originates from a 10;17 translocation. We have developed a dual-color FISH approach to detect RET/PTC rearrangements in interphase nuclei of thyroid lesions. By using a pool of three cosmids encompassing the RET chromosome region and a chromosome 10 centromeric probe, we could discriminate between the presence of an inversion (RET/PTC1 and RET/PTC3) or a translocation (RET/PTC2). We have investigated a series of thyroid tissue samples from Italian and French patients corresponding to a total of 69 PTCs and 22 benign lesions. Among PTCs, 13 (18.8%) showed a RET rearrangement, and 11 (15.9%) of these carried an inversion (RET/PTC1 or RET/PTC3) in more than 10% of the nuclei examined. Activated forms of RET were also observed in three adenomas. RT-PCR analysis on the same samples confirmed the presence and the type of rearrangement predicted using FISH analysis. An interesting difference in the frequency and type of RET rearrangements was detected between the Italian and the French patients. Furthermore, we identified a putative novel type of rearrangement in at least one PTC sample. Several PTCs carried a significant number of cells characterized by a trisomy or a tetrasomy of chromosome 10. Overall, the FISH approach in interphase nuclei represents a powerful tool for detecting, at the single cell level, RET/PTC rearrangements and other anomalies involving the RET chromosome region.

Chromosomal abnormalities in non-neoplastic renal tissue

Chromosome aberrations were studied in short-term cultures of non-neoplastic renal tissue and tumor tissue in 60 patients, 41 male and 19 female, with renal cell cancer (RCC), and in normal renal parenchyma from two cases, one male and one female, at autopsy with non-kidney related disease. Cytogenetic analysis of the non-neoplastic renal tissue from the patents with RCC revealed clonal chromosome aberrations in 32 of 60 (53%) cases: -Y, +Y, +X, +5, +7, +10, +12, +13, +18, +21, and del(9)(q12). In all other cases, non-clonal numerical and structural chromosome aberrations were observed, except for three cases of culture failure. Forty-two cases of RCC yielded clonal chromosomal abnormalities. Trisomy 7 was present in 23 cases, loss of Y in 14, trisomy 5 and 12 in three, trisomy 18 in two cases, and trisomy 10 in one case. Clonal chromosomal anomalies found in two cases from kidneys without neoplasia were trisomy 7, trisomy 12, and trisomy 18 in one case, and monosomy of chromosome 15 in the other. The proportion of aberrant cells in both cases (with clonal and non-clonal aberrations) was, on average, 24%. Apparently, chromosomal abnormalities only play a role in the process of oncogenesis when they are in the appropriate stage and lineage of differentiation.

Clonal chromosome changes in renal carcinoma do not correlate with clinical stages and histopathologic grades

We analyzed the correlations between chromosome abnormalities and clinical and histopathologic characteristics in 77 cases of renal cell carcinoma (RCC). Chromosome changes such as +5,+7,+8,+10,+18,+X,+Y, and -Y have been excluded from the analysis because they also occur in nonneoplastic kidney tissue and cytogenetic analysis indicates that these anomalies are not involved in tumor progression. The most frequent specific chromosome abnormalities in this sample were 3p rearrangements, trisomy 17, and hyperdiploidy and were not related to tumor stage or grade or to development of distant metastases.

Clonal aberrations of chromosomes X, Y, 7 and 10 in normal kidney tissue of patients with renal cell tumors

By means of G-banding techniques, chromosome aberrations were studied in short-term cultures of normal renal parenchymal cells from 45 patients with renal cell carcinoma. Clonal chromosomal aberrations were detected in 29 patients; loss of the Y chromosome as well as trisomy X, 5, 7, 9, 10, 12, and 18 was found. Chromosomes 7 and 10 were involved preferentially. Results of fluorescence in situ hybridization with chromosome 7- and 10-specific DNA probes on non-cultured normal kidney cells suggested that the aberrations developed in vivo.