Abstract:

Objective: To establish the drug-resistant cell line CAL-27/DDP of human tongue squamous cell carcinoma,and to discuss the mechanism of cisplatin resistance. Methods: The CAL-27/DDP cells were induced by increasing the concentrations of cisplatin in vitro. Then the cells were divided into CAL-27 group and CAL-27/DDP group.The cells in CAL-27 group were teated with common nutrient solution and the cells in CAL-27/DDP group were treated with nutrient solution containing different concentrations of cisplatin. The resistance cell line CAL-27/DDP with good growth status was formed 12 months after induction.The morphology of cells was observed by inverted microscope;the half maximal inhibitory concentration(IC₅₀) value and drug resistance index(RI) of cisplatin in the CAL-27 and CAL-27/DDP cells were detected by MTT assay;the cell cycle distribution of CAL-27 and CAL-27/DDP was detected by flow cytometry;the relative expression level of MDR1 in the cells was detected by reverse transcriptase polymerase chain reaction (RT-PCR) method;the relative expression level of P-glycoprotein(P-gp) in the cells was detected by Western blotting method. Results: The cells in CAL-27/DDP group could stably grow in the ordinary medium in a period and maintained its morphology and resistance status.Compared with CAL-27 group,the cells in CAL-27/DDP group showed particles and "cavity" samples,plenty of plasma,and increased doubling time (P<0.01);the RI was 18.09±0.30.Compared with CAL-27 group,the ratios of cells at G₁ phase and G₂ phase in CAL-27/DDP group were decreased,and the ratio of cells at S phase and the relative expression level of MDR1 mRNA in the CAL-27/DDP cells were increased significantly(P<0.01),and the relative expression level of P-gp was increased (P<0.01). Conclusion: The drug-resistant cell line CAL-27/DDP of human tongue squamous cell carcinoma is established sucessfully and the drug-resistant mechanismmay be related to the up-regulation of MDR1 and P-gp expression levels in CAL-27/DDP cells.

Key words: carcinoma,squamous cell, tongue neoplasms, cisplatin, drug resistance, MDR1, P-glycoprotein