Induction of apoptosis in human acute leukemia HL-60 cells by oligochitosan through extrinsic and intrinsic pathway

The underlying cellular and molecular mechanism about oligochitosan induced HL-60 cell apoptosis remained unknown. In the present study, we found oligochitosan treated HL-60 cells showed enhanced cleavage of poly (ADP-Ribose) polymerase PARP and p21 expression, accompanied with G0/G1cell cycle arrest. After treatment with oligochitosan, the pro-apoptotic molecules Fas, FADD and Bax were up-regulated whereas anti-apoptotic Bcl-2 expression in HL-60 cells was significantly decreased. Furthermore, galectin-9 mRNA expression was increased in the presence of oligochitosan. We thus over-expressed galectin-9S or galectin-9L and found galectin-9 could significantly increase the oligochitosan induced apoptotic rate of HL-60 cells. Collectively, our data demonstrated that oligochitosan might regulate cell cycle progression and induce HL-60 cell apoptosis through both extrinsic and intrinsic pathways.