Objective： To explore the apoptosis mechanism of Wenxia Changfu Formula （温下肠腑方, WCF） in reversing drug resistance of lung cancer in vivo. Metbods： Thirty model mice were randomly assigned to three groups： control group, cisplatin （CDDP） group, and WCF group. A transplanted tumor model of lung adenocarcinoma was established in all groups. Mice in the WCF group received intragastric administration of WCF （0.2 mL/10 g body weight） everyday in addition to CDDP intraperitoneally （5 mg/kg body weight） twice a week. The mice in the CDDP group received CDDP intraperitoneally （5 mg/kg body weight） twice a week, while the control group received normal saline intraperitoneally （0.2 mL/10 g body weight） everyday. The weight of the nude mice and respective tumors, tumor volume and tumor-inhibiting rate were measured. Electron microscopy was used to observe the existence of apoptosis body. Apoptosis index （AI） was detected by TdT-mediated dUTP nick end labeling staining. The expression of Fas and FasL mRNA was investigated by reverse transcription polymerase chain reaction, while immunohistochemistry was applied to detect the protein expression of Fas and FasL, caspase-3 and caspase-activated DNase （CAD）, respectively. Results： Compared with CDDP group and control group, WCF could significantly reduce the tumor volume from the 19th day and alleviate the tumor weight （P〈0.05）, and the apoptosis body was found in tumor cells in the WCF group. WCF could also enhance the level of AI, up-regulate the expression of caspase apoptosis pathway related protein caspase-3 and CAD, as well as the expression of Fas, FasL mRNA and protein （P〈0.05）. Conclusion： WCF could improve the sensitivity of tumor cells to CDDP and reverse the drug resistance by inducinq the apoptosis.
