Cleavage of nucleolin and AgNOR proteins during apoptosis induced by anticancer drugs in human salivary gland cells

BACKGROUND: To investigate the behavior of nuclear proteins in apoptosis induced by anticancer drugs in cultured human salivary gland (HSG) cells. METHODS: Dynamic alternations of nucleolin and argyrophilic nucleolar organizer region (AgNOR) proteins in anticancer drug-induced apoptosis of HSG cells and in a cell-free apoptotic system were examined using Western blot analysis and immunocytochemical method. RESULTS: The 110-kDa form of nucleolin and AgNOR protein decreased and the 80- and 95-kDa forms appeared during apoptosis in HSG cells and in a cell-free apoptotic system. In addition, the induction of DNA ladder formation coincided with the appearance of alternation of nucleolin and AgNOR proteins in a cell-free apoptosis. Nucleolin diffusely spread out into the nuclear material in the apoptotic body of HSG cells. CONCLUSIONS: The present results indicate that alternations of nucleolin and AgNOR proteins are associated with the induction of DNA fragmentation and the final active phase of apoptosis induced by anticancer drugs in malignant salivary gland cells.