Cytogenetic changes during the early stages of liver carcinogenesis in Chinese hamster: an in vivo--in vitro comparison.

Abstract Cytogenetic changes were investigated during the early stages of hepatic adenocarcinoma development in Chinese hamsters injected with a single dose of dimethylnitrosamine (DMN). An in vivo-in vitro comparison was made from 7 to 35 weeks after injection. A partial hepatectomy was used to stimulate mitosis for in vivo analysis, and the excised liver, grown to the primary culture stage, was used for chromosome analysis in vitro. Aneuploidy, tetraploidy, and chromosome aberrations increased significantly in the hepatic cells of DMN-treated animals in vivo, with no significant change over the 7- to 35-week period. No differences, however, could be detected between the primary cultures of control and DMN-treated animals because of an inherent tendency for all cultures to develop aneuploid stem lines at an early stage in culture. A preferential involvement of chromosome #6 in the single trisomic state was demonstrated in vitro and to a minor extent in vivo. The relevance of increased aneuploidy in early carcinogenesis and the differences between the in vivo and in vitro results are discussed.