ALTERED GROWTH PROPERTIES OF CHINESE-HAMSTER CELLS EXPOSED TO 1-METHYLGUANINE AND 7-METHYLGUANINE

  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (8) , 2285-2289
Abstract
Primary Chinese hamster embryo cell cultures yield cell lines with a finite lifetime in culture. If early-passage cells are exposed chronically to either of 2 normal degradation products of tRNA, 1-methylguanine or 7-methylguanine, they are converted to continuous lines with altered growth characteristics and morphology. The continuous cell lines have saturation densities 2- to 10-fold higher than finite control cultures, and some have the ability to grow in soft agar. Certain cultures have the general appearance of fibroblasts while others are more epithelial-like. Quantitative and qualitative alterations in the tRNA methyltransferases are early markers for neoplastic transformation in vivo and in vitro. tRNA methyltransferase activity in the continuous lines is elevated compared to that of finite Chinese hamster cells. Neoplastic transformation was demonstrated for a 1-methylguanine-derived line, and 1-methylguanine- and 7-methylguanine-treated cell lines exhibit characteristics similar to those of Chinese hamster cells transformed with the carcinogen 3,4-benzopyrene or the DNA tumor virus SV40.