Sensitivity of Gastric Cancer Cells to Chemotherapy Drugs in Elderly Patients and Its Correlation with Cyclooxygenase-2 Expression

Objective: To explore the sensitivity of gastric cancer cells to chemotherapy drugs in elderly patients andits correlation with cyclooxygenase-2 (COX-2) expression in cancer tissue. Materials and
Methods: Forty-threeelderly patients with gastric cancer (observation group) and 31 young patients with gastrointestinal tumors(control group) who were all diagnosed by pathology and underwent surgery in the 89th Hospital of ChinesePeople’s Liberation Army were selected. Drug sensitivity testing of tumor cells in primary culture was carriedout in both groups using a methyl thiazolyl tetrazolium (MTT) method, and the expression of COX-2 and thefactors related to multi-drug resistance (MDR) in cancer tissue were assessed by immunohistochemistry.
Results:The inhibition rates (IR) of vincristine (VCR), 5-fluorouracil (5-FU), oxaliplatin (L-OHP), mitomycin (MMC)and epirubicin (eADM) on tumor cells in the observation group were dramatically lower than in the controlgroup, with statistical significance (P<0.05 or P<0.01). The positive rates of COX-2, glutathione s-transferase-π(GST-π) and P glycoprotein (P-gp) expression in cancer tissue in the observation group were all higher than incontrol group (P<0.05), while that of DNA topoisomerase IIα (TopoIIα) expression lower than in the control group(P<0.01). In the observation group, COX-2 expression in cancer tissue had a significantly-positive correlationwith GST-π and P-gp (r=0.855, P=0.000; r=0.240, P=0.026), but a negative correlation with TopoIIα (r=−0.328,P=0.002). In the control group, COX-2 expression in cancer tissue was only correlated with P-gp positively(r=0.320, P=0.011). Bivariate correlation analysis displayed that COX-2 expression in cancer tissue in theobservation group had a significantly-negative correlation with the IRs of 5-FU, L-OHP, paclitaxel (PTX) andeADM in tumor cells (r=−0.723, P=0.000; r=−0.570, P=0.000; r=−0.919, P=0.000; r=−0.781, P=0.000), but withhydroxycamptothecine (HCPT), VCR and 5-FU in the control group (r=−0.915, P=0.000; r=−0.890, P=0.000;r=−0.949, P=0.000).
Conclusions: Gastric cancer cells in elderly patients feature stronger MDR, which may berelated to high COX-2 expression.