Effects of low temperature and lipid modification on the proliferation of cultured mammalian cells

Abstract

The effects of temperature on cell proliferation have been determined for two mouse lines: LM cells, a spontaneously transformed line, and R1 cells, a variant line which displays a less transformed phenotype and which was derived from LM cells by treatment with concanavalin A. Low temperature has a selective effect on the extent of proliferation of LM cells. At 28 °C, LM cells grow to only one-fourth the density which they achieve at 36 °C, whereas R1 cells grow to approximately the same maximal density at both these temperatures. Shifting the growth temperature to 36 °C results in further proliferation of LM cells grown to maximal density at 28 °C. Shifting the temperature of growth from 36 to 28 °C arrests the proliferation of only those LM cell cultures that have already attained the highest density which can be achieved when LM cells are grown entirely at 28 °C. The influence of exogenously incorporated fatty acids on proliferation of LM cells has been determined at different temperatures. At 36 °C, a temperature near the physiological range, none of the fatty acid supplements caused increases in maximal growth density. Most fatty acid supplements caused decreases, but there was no correlation between the fatty acids which caused a decreased extent of proliferation at 36 °C and any change in lipid physical state which these fatty acids would be likely to produce. At 28 °C, there is a marked decrease in the maximal density which LM cells achieve. This phenomenon is reversed by fatty acid supplements (oleic and linolenic acids) which contain cis-olefinic bonds and which decrease the critical temperatures for lectin binding and lectin-mediated agglutination phenomena. Fatty acid supplements which increase the critical temperatures for these phenomena, nonadecanoic acid and elaidic acids, have little effect or are growth inhibitory at 28 °C.