Characteristics of an infinite life span diploid human fibroblast cell strain and a near-diploid strain arising from a clone of cells expressing a transfected v-myc oncogene.
Diploid human fibroblasts were transfected with a plasmid carrying a v-myc oncogene linked to the neo gene or with a vector control carrying a neo gene. Drug-resistant clones were isolated and subcultured as needed. All populations went into crisis and eventually senesced. But while they were senescing, viable-appearing clones were noted among the progeny of a transfected population that expressed the v-myc oncogene. After several months, these cells began replicating more rapidly. Karyotype analysis indicated that they were clonally derived since all of them had 45 chromosomes, including 2 marker chromosomes. This cell strain was designated MSU-1.1. Similar analysis showed that cells from an earlier passage were diploid. These cells were designated MSU-1.0. Both strains have undergone more than 200 population doublings since their siblings senesced, without any change in chromosome complement. Both strains express the v-myc protein and have the same integration site for the transfected v-myc and neo genes. The MSU-1.0 cells cannot grow without exogenously added growth factors. The MSU-1.1 cells grow moderately well under the same conditions and grow to a higher saturation density than MSU-1.0 cells. Since the chance of human cells acquiring an infinite life span in culture is very rare, the data suggest that MSU-1.1 cells are derived from MSU-1.0 cells. The expression of v-myc is probably required for acquisition of an infinite life span, since this phenotype did not develop in populations not expressing this oncogene. However, expression of v-myc is clearly not sufficient, since all of the progeny of the clone that gave rise to the MSU-1.0 cells expressed this oncogene, but the vast majority of them senesced.
Morgan
T L
TL
Department of Microbiology, Michigan State University, East Lansing 48824.
Yang
D J
DJ
Fry
D G
DG
Hurlin
P J
PJ
Kohler
S K
SK
Maher
V M
VM
McCormick
J J
JJ
D000818:Animals; D015139:Blotting, Southern; D016923:Cell Death; D002455:Cell Division; D002461:Cell Line, Transformed; D002645:Chickens; D002871:Chromosome Banding; D002999:Clone Cells; D016895:Culture Media, Serum-Free; D004171:Diploidy; D005347:Fibroblasts / Q000166:cytology*; D016259:Genes, myc; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007621:Karyotyping; D008297:Male; D051379:Mice; D009368:Neoplasm Transplantation; D013997:Time Factors; D014162:Transfection
D016895:Culture Media, Serum-Free; D006133:Growth Substances