Crocin Exhibits Antitumor Effects on Human Leukemia HL-60 Cells In Vitro and In Vivo

Crocin is a carotenoid of the saffron extract that exhibits antitumor activity against many human tumors. However, the effects of crocin on HL-60 cells in vivo have not been evaluated. This study aimed to examine the effects of crocin on HL-60 cells in vitro and in vivo and investigate the underlying mechanisms. HL-60 cells were treated by crocin, and cell proliferation, apoptosis, and cell cycle profiles were examined by MTT assay, AO/EB staining, and flow cytometry, respectively. Furthermore, HL-60 cells were xenografted into nude mice and treated by crocin, the tumor weight and size were calculated, and the expression of Bcl-2 and Bax in xenografts was detected by immunohistochemical staining. The results showed that crocin (0.625-5 mg/mL) inhibited HL-60 cell proliferation and induced apoptosis and cell cycle arrest at G0/G1 phase, in a concentration and time-dependent manner. In addition, crocin (6.25, 25 mg/kg) inhibited the tumor weight and size of HL-60 xenografts in nude mice, inhibited Bcl-2 expression, and increased Bax expression in xenografts. In summary, crocin inhibits the proliferation and tumorigenicity of HL-60 cells, which may be mediated by the induction of apoptosis and cell cycle arrest and the regulation of Bcl-2 and Bax expression.