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Malignant transformation of human fibroblasts previously immortalized with 60 Co gamma rays
Author(s) -
Mihara K.,
Bai L.,
Kano Y.,
Miyazaki M.,
Namba M.
Publication year - 1992
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910500426
Subject(s) - malignant transformation , transplantation , biology , phenotype , fibroblast , mutation , embryo , cell culture , transformation (genetics) , microbiology and biotechnology , serial passage , gene , cancer research , pathology , genetics , medicine , surgery
Abstract Normal human fibroblasts obtained from a whole embryo were malignantly transformed with only 60 Co gamma rays, but after extensive passage. The fibroblasts were exposed intermittently to 60 Co gamma rays, 13 times, 2,800 rads in total, from the primary culture to the 40th passage level. At the 50th passage level the cells became morphologically changed, showing chromosomal abnormalities, and serial passages showed them to be immortalized. They were not tumorigenic on transplantation into nude mice, but became malignant after extensive passage; i.e., at the 547th passage level and 2,800 days after initiation of the culture. Our results indicate that several different genotypic changes are necessary for malignant transformation of human cells over long periods. No mutation at codons 12 and 61 of H‐, K‐ and N‐ ras was detected in the malignant cells. Thus, this system may be useful to detect other cellular genes that may contribute to the malignant phenotypes of human fibroblasts.