ABSTRACT
OBJECTIVE To explore the mechanism of Compound lizard powder reducing cisplatin resistance in gastric cancer by regulating glycolytic activity based on phosphoinositide 3-kinase（PI3K）/protein kinase B（Akt） signaling pathway. METHODS Human gastric cancer MKN45 and MKN45/DDP （cisplatin-resistant） cells were cultured in vitro and intervened with different mass concentrations of cisplatin （0.1， 0.2， 0.4， 0.8， 1.6， 3.2 μg/mL） to detect the survival rate， half inhibitory concentration （IC50） and drug resistance index. MKN45/DDP cells were inoculated subcutaneously in the right anterior axilla of nude mice to prepare a transplanted tumor model of gastric cancer. After successful modeling， they were randomly divided into model group， cisplatin group （0.002 g/kg）， Compound lizard powder group （2.8 g/kg） and combination group （the same dose as each single drug group）， with 8 nude mice in each group. Each administration group was given relevant solution， twice a week （cisplatin， i.p.） or twice a day （Compound lizard powder， i. g.）， for 4 consecutive weeks. During the experiment， the body weight of nude mice was monitored， and tumor volume and inhibitory rate of tumor were calculated. The levels of inflammatory factors （tumor necrosis factor- α， interleukin-6） in tumor tissue， the mRNA and protein expressions of multidrug resistance-associated protein 1 （MRP1）， P-glycoprotein （P-gp）， glucose transporter-1 （GLUT1） and lactate dehydrogenase A （LDHA）， as well as the protein expressions of PI3K， phosphorylated PI3K （p-PI3K）， Akt， phosphorylated Akt （p-Akt）， hexokinase-2 （HK2） and pyruvate kinase M2 （PKM2） were all detected. RESULTS With the intervention of different concentrations of cisplatin， the survival rate of MKN45/DDP-resistant cells was significantly higher than that of MKN45 parent cells （P＜0.05）. IC50 value of MKN45/DDP and MKN45 cells were（1.052 0±0.221 9） and （0.372 1±0.238 0）μg/mL， and the drug resistant index was 2.827. Compared with the model group， cisplatin group， Compound lizard powder group and combination group all had certain inhibitory effects on the tumor growth in nude mice； the inhibitory rates of tumor increased significantly （P＜0.05）； the levels of inflammatory factors， the mRNA and protein expressions of MRP1， P-gp， GLUT1 and LDHA （except for cisplatin group）， the phosphorylation levels of PI3K and Akt protein （except for cisplatin group） as well as the protein expressions of HK2 and PKM2 were decreased significantly， while the combination group was significantly better than the cisplatin group （P＜0.05）. CONCLUSIONS Compound lizard powder may inhibit tumor growth in transplanted tumor model nude mice with gastric cancer-resistant cells by reducing the secretion of tumor-related inflammatory factors， inhibiting the expression of glycolysis， drug resistance-related proteins and genes， inhibiting the activation of the PI3K/Akt signaling pathway， thus having a certain effect of enhancing cisplatin efficacy and reversing drug resistance.