Sterol synthesis in cultured human renal cell cancer

Studies on sterol synthesis in cultured human renal cell carcinoma were conducted in an attempt to elucidate the mechanism by which clear cell tumors accumulate cholesterol in the cytoplasm. Cultured renal cell carcinoma requires serum lipoproteins for optimal growth. In some renal cell carcinomas cellular cholesterol content was significantly higher than that present in cultured kidney cells under similar conditions. Renal cell carcinoma synthesizes sterols from labeled acetate. The rate of sterol synthesis is inversely proportional to the levels of exogenous cholesterol in the growth medium, suggesting the presence of a negative feedback mechanism. In addition, the conversion of 27-carbon-atom sterol precursors to cholesterol appears to be slow and inefficient under the presnt conditions. We conclude that an aberrant regulation of cholesterol synthesis cannot be invoked necessarily to explain cholesterol accumulation in renal cell carcinoma.