Epidermal growth factor elevates the activity levels of glycolipid sulfotransferases in renal-cell-carcinoma cells

Abstract

Accumulation of sulfoglycolipids associated with markedly elevated levels of glycolipid-sulfotransferase activity was previously demonstrated in human renal-cell-carcinoma cells. To elucidate the regulatory mechanisms of sulfoglycolipid metabolism in renal-cell carcinoma, effects of various growth factors on the sulfotransferase-activity levels were investigated using a human renal-cell-carcinoma cell line, SMKT-R3. Exogenous epidermal growth factor (EGF) significantly increased the activity levels of the sulfotransferases in a dose-dependent manner, but did not change that of arylsulfatase A, which hydrolyzes sulfoglycolipids. Furthermore, metabolic labeling with ³⁵S-sulfate revealed that the addition of EGF to the culture medium of the cells resulted in an increment of sulfoglycolipid synthesis. The expression of the EGF receptor on SMKT-R3 cells was demonstrated by affinity cross-linking with ¹²⁵l-EGF. These observations suggest that EGF can regulate sulfotransferase-activity levels in renal-cell-carcinoma cells, and function as one of the regulatory factors of sulfoglycolipid synthesis in these carcinoma cells.