Demonstration of lipolytic activity from cultured human melanoma cells

Cancer bearing is often accompanied by debilitating cachexia manifested as body weight loss and derangements of host metabolism. We studied lipolytic (fat-mobilizing) activity and glycerol accumulation in culture media exposed to six different human cell lines. An in vitro adipocyte bioassay measured lipolysis. Media from three of four human melanoma cell lines demonstrated significantly elevated lipolytic activities (279-817% of fibroblast-exposed, control medium), as well as significantly more glycerol accumulation (276-1643% of fibroblast medium) which directly correlated with the increased lipolytic activity. Increased lipolytic activity and glycerol accumulation were not generalized phenomena seen with all growing tumor cells, as two cell lines (a human colon carcinoma and the fourth human melanoma line) demonstrated neither significantly increased lipolytic activity nor increased glycerol accumulation compared to fibroblast control medium. This study suggests that certain tumor cells are capable of transferring a lipolysis-promoting activity to the media which bathe them. This activity is demonstrable both as increased lipolytic activity in a bioassay of lipolysis, and as an accumulation of glycerol (an end product of triglyceride lipolysis), in the medium exposed to the growing cells. The tumor factor(s) responsible for this lipolysis-promoting activity may account for the fat wasting that often accompanies malignancy.