Effects of inhibitors of lipid synthesis on transformation in chicken embryo fibroblasts infected with Rous sarcoma virus

Abstract

Cultures of chicken embryo fibroblasts infected with the temperature-sensitive transformation mutant of Rous sarcoma virus (RSV), tsLA24PR-A, were arrested in the cell cycle by incubation at 41 °C in a defined medium without serum. After shifting to the permissive temperature, 35 °C, these cells assumed the characteristics of transformed cells: They increased their uptake of [ 3H]2-deoxyglucose, assumed the transformed morphology, and increased the percentage of nuclei labeled with [ 3H]thymidine. The effects on transformation of 25-hydroxycholesterol, an inhibitor of sterol synthesis, and of cerulenin, an inhibitor of fatty acid synthesis and a partial inhibitor of sterol synthesis, were studied in this system. Cells were able to adopt these characteristics of transformed cells in the presence of 25-hydroxycholesterol. When given 25-hydroxycholesterol 3 h before the temperature shift they sustained the increase in 2-deoxyglucose uptake, but when 25-hydroxycholesterol was given 12 h before the shiftdown from 41 °C, these cells were subsequently unable to maintain the increased rates of 2-deoxyglucose uptake at 35 °C. Cells treated with cerulenin 2 h before the shift also demonstrated only a transient increase in 2-deoxyglucose uptake. We conclude that in this system the early events of transformation can occur in a completely defined medium and that these early events do not require normal rates of sterol synthesis.