Decreased expression of the pro-apoptotic protein Par-4 in renal cell carcinoma

Par-4 is a widely expressed leucine zipper protein that confers sensitizati on to apoptosis induced by exogenous insults. Because the expression of gen es that promote apoptosis may be down-regulated during tumorigenesis, we so ught to examine the expression of Par-4 in human tumors, We present here ev idence that Par-4 protein levels were severely decreased in human renal cel l carcinoma specimens relative to normal tubular cells, Replenishment of Pa r-4 protein levels in renal cell carcinoma cell lines conferred sensitivity to apoptosis, Because apoptosis may serve as a defense mechanism against m alignant transformation or progression, decreased expression of Par-4 may c ontribute to the pathophysiology of renal cell carcinoma.