Chromosomes of "minimal deviation" hepatomas and some other transplantable rat tumors.

Abstract

Summary Chromosome studies were done on 35 transplantable rat hepatoma lines, including a number of “minimal deviation” tumors. Cell suspensions were obtained directly from the solid neoplasms by trypsinization, and tumor metaphases were distinguished from contaminating host metaphases by sex chromosome differences. Six tumor lines had a normal chromosome number—42—but only 9618A had a completely normal karyotype. Minimal abnormalities, which could represent normal karyotype variation, were observed in 4 others (7794A, 7800, 9098, 9121), and 9108 had definite changes involving several small chromosomes. This tumor also showed 50% transition to 43 chromosomes in a later transplant generation. The six diploid tumors had an intermediate growth rate and variable enzyme alterations. The 29 aneuploid tumors all had different karyotypes with no obvious correlation between specific chromosome alterations and specific enzyme changes. Some of these tumors were less deviated metabolically than the diploid neoplasms (e.g., 7793, 45 chromosomes) and some were slower growing (e.g., 7787, 44 chromosomes). Chromosome studies will permit identification of tumors which are “minimally deviated” from a cytogenetic standpoint, but a variety of metabolic alterations may still be present.