In the present study, we investigated the induction of apoptosis by N-nitrosopyrrolidine (NPYR) and N-nitrosodimethy-lamine (NDMA) in two human cell lines: HL-60 (leukemia) and HepG2 (hepatoma). Apoptotic cells were i...In the present study, we investigated the induction of apoptosis by N-nitrosopyrrolidine (NPYR) and N-nitrosodimethy-lamine (NDMA) in two human cell lines: HL-60 (leukemia) and HepG2 (hepatoma). Apoptotic cells were identified by: 1) chromatin condensation, 2) flow cytometry analysis and 3) poly (ADP-ribose) polymerase cleavage. Both cell lines exhibited morphological changes consistent with apoptotic events following treatment with N-nitrosamines. Flow cytometry analysis showed that both N-nitrosamines induced apoptotic cell death in a concentration and time dependent- manner. NPYR was stronger than NDMA, since it induced a significant apoptotic cell death after 72 h starting from a concentration of 10 mM, whereas NDMA was effective at 27 mM. Furthermore, NPYR and NDMA caused the cleavage of PARP in HL-60 cells whereas no PARP cleavage was detected in HepG2 cells. However, NPYR- and NDMA-induced cell death in HepG2 cells was prevented by specific caspase inhibitors. Caspase-8 mediated main pathway and was responsible for 76% (NPYR) and 64% (NDMA) inhibition of apoptosis. The data demonstrate that NPYR and NDMA induce apoptosis in HL-60 and HepG2 cell lines via caspase-dependent pathway.展开更多
文摘In the present study, we investigated the induction of apoptosis by N-nitrosopyrrolidine (NPYR) and N-nitrosodimethy-lamine (NDMA) in two human cell lines: HL-60 (leukemia) and HepG2 (hepatoma). Apoptotic cells were identified by: 1) chromatin condensation, 2) flow cytometry analysis and 3) poly (ADP-ribose) polymerase cleavage. Both cell lines exhibited morphological changes consistent with apoptotic events following treatment with N-nitrosamines. Flow cytometry analysis showed that both N-nitrosamines induced apoptotic cell death in a concentration and time dependent- manner. NPYR was stronger than NDMA, since it induced a significant apoptotic cell death after 72 h starting from a concentration of 10 mM, whereas NDMA was effective at 27 mM. Furthermore, NPYR and NDMA caused the cleavage of PARP in HL-60 cells whereas no PARP cleavage was detected in HepG2 cells. However, NPYR- and NDMA-induced cell death in HepG2 cells was prevented by specific caspase inhibitors. Caspase-8 mediated main pathway and was responsible for 76% (NPYR) and 64% (NDMA) inhibition of apoptosis. The data demonstrate that NPYR and NDMA induce apoptosis in HL-60 and HepG2 cell lines via caspase-dependent pathway.
