ISSN:
0095-9898
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
The transformation process induced by polyoma virus in mass cultures of hamster embryo cells has been analyzed chronologically for several parameters: morphology, karyology, antigenicity and transplantability. Morphological changes, as manifested by the altered growth pattern of the culture, were the first indication of transformation. The expression of morphological transformation differed among colonies from a single culture and among the various cell lines; its pattern could change with prolonged growth of the cultures. Established lines originating from each transformed culture eventually produced tumors in syngeneic and allogeneic animals. Tumorigenicity was low (MTD ± 106) soon after morphological transformation, but increased progressively as the cells were carried in vitro (MTD 〈 103). Polyoma virus disappeared in eight lines, but persisted in one. The non-virus releaser lines were resistant to superinfection with polyoma virus. The polyoma-induced transplantation antigen (PV-ITA) was found in four of six lines; it was not demonstrable in later passages of some lines that were initially positive and was not detected in the virus carrier culture. The polyoma-induced CF antigen (PV-ICFA), however, was present in all the cultures exposed to polyoma virus even at passage levels where the PV-ITA was not demonstrable. Some chromosomal changes in type and in ploidy were present at, or shortly after, the time of morphological transformation. Although very low at first, frequency of chromosome changes increased with time in a random pattern. Three of four lines remained near-diploid, the fourth line became subtetraploid soon after morphological transformation. The incidence of chromosomal damage (chromatid breaks, dicentrics and fragments) was low in all four lines analyzed, even in the virus carrier culture. There was a parallel increase in frequency of abnormal metaphases and of transplantability.It is concluded that after an initial and yet obscure polyoma virus cell interaction, cells evolve toward malignancy in a pattern that does not show specificity for the inducing virus. The viral genome, if present in the transformed cells, does not appear to direct or regulate the evolution of the cells in vitro.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1030660313
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