Neoplastic transformation of human diploid fibroblasts (KMST‐6) by treatment with ⁶⁰Co gamma rays

Abstract

Normal fibroblasts (KMS-6) derived from a human embryo were transformed in culture into neoplastic cells (KMST-6) by repeated treatment with 60Co gamma ray irradiation. Repeated treatment was necessary to obtain transformation. Control normal cells exhibited normal karyotype (46, XX) and stopped dividing due to cellular ageing at the 40th passage. The transformed cells are presently growing indefinitely (140th passage) and exhibit prominent karyologic aberrations, both numerical and structural. These 2 characteristics, indefinite growth and abnormal karyotype, are thought to be the most important parameters for neoplastic transformation of human fibroblasts. Other indispensable parameters are the presence of active mitotic figures on confluent cell sheets and colony-type morphology. Transformed cells grow into colonies with relatively smooth edges, while normal fibroblasts form colonies with jagged edges, due to the protrusion of growing fibroblasts. Other parameters, such as elevated plating efficiency, enhanced colony formation in soft agar, low serum requirement for growth, high saturation density, and acquisition of transplantability, are not reliable in the early stages of transformation. These parameters probably appear at rather later stages of transformation following several cell divisions. Among other characteristics, the transformed KMST-6 cells exhibit a B-type isozyme pattern of glucose-6-phosphate dehydrogenase, lactate-dehydrogenase isozyme pattern of human origin, no evidence of viral infection and no production of C-type virus particles.

Expression of mutant telomerase in immortal telomerase-negative human cells results in cell cycle deregulation, nuclear and chromosomal abnormalities and rapid loss of viability

“…The SUSM-1 cell line, derived from 4-nitroquinoline transformed liver ®broblasts (Namba et al, 1981), was grown in Dulbecco's modi®ed Eagle's medium with 10% FCS.…”

Differences in resistance to 5-fluorouracil as a function of cell cycle delay and not apoptosis

“…The cell lines used were the normal human embryo fibroblast cell line KMS-6, its cobalt-60-irradiated immortalised derivative KMST (Namba et al, 1988) and the tumorigenic cell line KN-NM established from the KMST cell line by transfection with an activated N-ras oncogene cDNA (Kinsella et al, 1990). This series of cell lines was chosen as a model for the progression of a normal cell towards tumorigenicity as is observed in vivo.…”

In vitro models of carcinogenesis: expression of recessive genes by chromosomal mutations.

“…Chromosomal mutations result from large-scale changes including translocations, rearrangements or deletions, rather than point mutations such as those associated with ras gene activation (4). X-radiation, for example, is an efficient inducer of stable chromosomal rearrangements (6), and fully transformed, immortalized human cells in vitro are characteristically aneuploid with multiple chromosomal abnormalities (7).…”