Effects of baicalin on HL-60 cell xenografts in nude mice and its mechanism / 中国实验血液学杂志

ABSTRACT

This study was aimed to investigate the effects of baicalin on HL-60 cell xenografts in nude mice in vivo and explore its mechanism. Xenograft tumor model of HL-60 cells in nude mice was established, which was divided randomly into 6 groups negative control group (injection of 5% NaHCO(3)), 25, 50 and 100 mg/kg baicalin groups, combination group (50 mg/kg baicalin + 2 mg/kg VP16) and positive control group (VP16 4 mg/kg). The nude mice with HL-60 cell xenografts were treated with drugs via intraperitoneal injection daily. After treatment for 14 days average weigh and inhibitory rate of transplanted tumor stripped from 5 nude mice in each group were calculated, and the ultrastructure change of xenografts cells were tested by transmission electron microscopy. Histopathologic examination was used to observed the change of main organs in nude mice. The expression of signaling molecular PI3K/Akt proteins extracted from xenografts was detected by Western blot. The effects of baicalin on overall survival time in nude mice with HL-60 cell xenografts were evaluated. The results showed that baicalin could inhibit the growth of transplanted tumors in dose-dependent manner. There were more necrotic and apoptotic cells in mice of baicalin-treated groups and combination group than that in mice of negative control group. Baicalin could inhibit the proliferation of HL-60 cells in vivo by down-regulating the PI3K/Akt/mTOR signal pathway, where the expressions of p-Akt, mTOR and p-mTOR proteins decreased compared with negative control group, and no significant difference of Akt expression was found between different groups. Compared with negative control group, the median survival time of mice in combination group was more prolongated (P < 0.05). It is concluded that baicalin can inhibit growth and induce apoptosis of HL-60 cell xenografts in nude mice, and prolong median survival time of nude mice. The possible mechanisms may be related to inhibition of Akt activity and down-regulation of the PI3K/Akt/mTOR signal pathway. The combination of baicalin and VP16 shows a synergistic effect on inhibiting growth of HL-60 cell xenografts in nude mice.