Apoptosis and expression of the bcl-2 proto-oncogene in the fetal and adult human kidney: Evidence for the contribution of bcl-2 expression to renal carcinogenesis

bcl-2 was identified as a transcript associated with the t(14;18) and imparts resistance to apoptotic cell death. bcl-2 is normally expressed in many tissues and exhibits remarkable structural and functional conservation. Using immunohistochemical and in situ DNA labeling techniques we examined the localization of bcl-2 in the developing human kidney. bcl-2 expression was rapidly upregulated in the induced metanephrogenic mesenchymal cells that differentiate into renal vesicles and nephrons. bcl-2 expression was undetectable in uninduced mesenchyme and in the renal ampullae and associated collecting system. The distribution of apoptotic cells within the developing kidney was inversely correlated with expression of bcl-2. The localization of bcl-2 protein in the adult human kidney also was examined. bcl-2 was expressed at high levels in all renal neoplasms examined providing a potential basis for the deregulation of apoptosis in the development and progression of these tumors.