Abstract
This study evaluated the sensitivities of gastric cancer cells to various chemotherapy drugs, and investigated the relationship between the expression of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) and multidrug resistance. Drug sensitivities were determined using a methyltetrazolium assay: expression levels of P-gp and MRP were measured using immunohistochemistry. On purification culture, gastric cancer cells were found to be most sensitive to cisplatin, mitomycin and adriamycin, moderately sensitive to etoposide and 5-fluorouracil, and less sensitive to homocamptothecin and methotrexate, with sensitivities of 76.7%, 70.0%, 66.7%, 60.0%, 56.7%, 43.3% and 30.0%, respectively. Positive expression for P-gp and MRP in gastric cancer tissues was 41.7% and 29.2%, respectively;co-expression of P-gp and MRP in cancer tissue was 23%. The drug-resistant groups had higher positive expression of P-gp and MRP compared with the drug-sensitive groups. In conclusion, expression of P-gp and MRP seems to be associated with multidrug resistance in gastric cancer.