Karyotype and Tumorigenicity of 1-Methylguanine-Transformed Chinese Hamster Cells2

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Abstract
Chinese hamster embryo cells transformed with the tRNA catabolite 1-methylguanine were characterized by Giemsa-banded karyotyplng and by their tumorigenic potency in athymic nude mice. All seven 1-methylguanine-transformed cell lines were hyperdiploid with a modal chromosome number of 23. Three of these lines had an additional marker chromosome derived from the long (q) arm of chromosome #4, and they had alterations of chromosome #5 as well. Two of these three cell lines were tumorigenic. Nonrandom chromosome changes were observed in the other four 1-methylguanine-transformed cell lines, which Included the addition of all or a portion of chromosome #6. One of these cell lines was also tumorigenic in nude mice. Specific cytogenetic changes were observed in most 1-methylguanine-transformed populations in contrast to the karyotypic heterogeneity of a benzo[a]pyrene-transformed cell line.