Kinetics of growth and ectopic production of human chorionic gonadotropin by an ovarian cystadenocarcinoma cell line maintained in vitro.

An established ovarian papillary cystadenocarcinoma cell line, designated 163, released immunoreactive human chorionic gonadotropin (HCG) in vitro into the culture medium. The maximal rate of this ectopic activity (10 to 15 ng/day/10(6) cells) occurred at the onset of the logarithmic phase of cell growth and greatly exceeded the intracellular HCG content of cells approaching confluency (0.037 ng/10(6) cells). The HCG production was not detected during the plateau phase of growth. The rate of cellular proliferation and HCG release depended upon the frequency of media change in a manner suggesting that the two processes are interrelated and may be affected by such environmental factors as cell density, nutrient availability, and the accumulation of waste products. The addition of purified HCG to the cultures had no appreciable effect on either the cell growth or the accumulation of HCG. The release of HCG into the medium was greatly stimulated in the presence of sodium butyrate at concentrations from 1 to 10 mM, despite the fact that these concentrations of butyrate resulted in a marked decrease in the cell number/culture in comparison with control media. Equivalent amounts of sodium acetate had no effect on either cell growth or the release of HCG.