The induction of growth factor-independence in murine myelocytes by oncogenes results in monoclonal cell lines and is correlated with cell crisis and karyotypic instability.
Infection of established (IL-3)-dependent hematopoietic cell lines with Abelson murine leukemia virus (A-MLV) abrogates their requirement for IL-3 and leads to non-autocrine growth factor-independent cells. We were interested to determine whether A-MLV can induce IL-3 independence also in non-established cells. To obtain long-term cultures of diploid myelocytes, splenic hematopoietic cells were first infected with MMCV, a murine retrovirus carrying the avian v-myc oncogene. These cultures were superinfected with A-MLV. In three independent experiments, the first growth factor-independent cells appeared between 18 and 43 days after superinfection with A-MLV and represented .02-1% of the population. Furthermore, the cultures that became growth factor-independent were monoclonal for integration of the v-abl gene. These results indicate that the acquisition of growth factor-independence after superinfection of v-myc-expressing cells with A-MLV is a rare event. The low frequency of growth factor-independent cells was not due to a low percentage of infected cells, since 15-25% of the cells were infected with A-MLV after 7 days. The first appearance of growth factor-independent cells coincided with crisis in the cultures, as indicated by a high incidence of cell death and a reduced overall growth rate of the cell populations. These growth factor-independent cells exhibited variable karyotypes, including many that were near-triploid to near-tetraploid. In summary, growth factor-independence induced by super-infection with A-MLV, like that induced by double-infection with v-myc- and v-H-ras-containing viruses, is associated with unstable karyotypes. The growth factor-independent cells show variable ploidy characteristic of cells which survived crisis.
Vogt
M
M
Molecular Biology and Virology Laboratory, Salk Institute, San Diego, CA 92138.
Lesley
J
J
Bogenberger
J M
JM
Haggblom
C
C
Swift
S
S
Haas
M
M
D000818:Animals; D015139:Blotting, Southern; D002455:Cell Division; D002460:Cell Line; D002470:Cell Survival; D002999:Clone Cells; D005434:Flow Cytometry; D007377:Interleukin-3 / Q000235:genetics*; D007621:Karyotyping; D009052:Leukemia Virus, Murine / Q000235:genetics; D007942:Leukemia, Experimental / Q000235:genetics*; D007951:Leukemia, Myeloid / Q000235:genetics; D051379:Mice; D009857:Oncogenes; D011003:Ploidies; D015163:Superinfection / Q000235:genetics
D007377:Interleukin-3