Effect of rapamycin (RAPA) on the growth of lung cancer and its mechanism in mice with A549.

OBJECTIVE To investigate the effects of rapamycin (RAPA) on the tumor growth of lung cancer in the mice bearing A549 and the mechanisms. METHODS 60 mice with A549 lung cancer models established were randomly divided into model group, low RAPA dose group and high RAPA dose group. The low dose group underwent intraperitoneal injection of 1.5 mg/kg RAPA, while the high dose group underwent intraperitoneal injection of 4.5 mg/kg RAPA, and the control group was given the same volume of PBS. 21 d after the administration, the changes of the tumor growth and survival rates of three groups were observed. RT-PCR and Western blot were utilized to analyze Caspase-3 mRNA and protein levels in the tumor tissues of the mice, and TUNEL staining method was used to analyze the cellular apoptosis of tumor tissues. RESULTS Compared with the model group, the low and high dose groups significantly inhibit tumor growth and have remarkably higher survival rates (P<0.05). The high dose group has obviously better effects on inhibiting tumors and a higher survival rate than low dose group (P<0.05). Compared with the model group, the low and high dose groups have significantly increased Caspase-3 mRNA and protein levels in tumor tissues (P<0.05), and higher cellular apoptosis rates in tumor tissues (P<0.05); Caspase-3 mRNA and protein levels and apoptosis rates of the mice's tumor tissues of high dose group are markedly higher than those of low dose group (P<0.05). CONCLUSIONS RAPA can significantly increase the expression of Caspase-3 in tumor tissues and promote the apoptosis of tumor tissue cells, and thus achieve good anti-tumor effects.