Hexose sugar transport activity in a mouse fibroblast cell line temperature sensitive for expression of the transformed phenotype

Abstract

A temperature-sensitive mouse fibroblast cell line was used to examine the relationship between hexose sugar uptake rates and the control of cell growth. The cell line (ts-H6-15) is a derivative of SV-3T3 cells, exhibiting a transformed phenotype at 32 degrees C and a normal phenotype at 39 degrees C. For cells actively growing at either temperature, a marked decrease in the rate of 3-O-methyl-D-glucose (3-O-MeG) transport is observed as cell population density increases. At cell population densities tested, 3-O-MeG transport rates (at a common assay temperature) were greater in H6-15 cells grown at 32 degrees C than at 39 degrees C, with the enhancement being maximal at the lowest cell densities. The effect of low serum-arrest on H6-15 cells revealed that cells growing at 39 degrees C arrest in G1, while cells at 32 degrees C stop more randomly throughout their cycle. Under conditions of low serum-arrest the rate of 3-O-MeG transport remained as high as in actively growing cells at both 32 degrees C and 39 degrees C. However, 2-deoxyglucose uptake rates were growth state-dependent at 39 degrees C, indicating perhaps metabolic as well as membrane-level control of sugar accumulation. These results further demonstrate that rates of hexose sugar transport by themselves are not always absolutely correlated with rates of cell proliferation and, thus, may be reliable predictors of cell growth potential.