BACKGROUNDTo study the levels of expression, coexpression, and clinical significancer of four multidrug resistance factors in lung cancer.

METHODSThe P glycoprotein (P-gp), multidrug-resistance-associated protein (MRP), lung resistance protein (LRP), glutathione S-transferase (GST-π) of 60 lung cancer patients were detected by using immunohistochemical method.

RESULTSThe positive rate of the drug resistance factor was 53.3% (32/60), 63.3% (38/60), 70.0% (42/60), and 80.0% (48/60) for P-gp, MRP, LRP, and GST-π respectively. Patients with NSCLC had significantly higher expression of the drug resistance factors than those with SCLC. On the other hand, no relationship was observed between the expression of drug resistance factors and TNM stage and cell differentiation. The coexpression rate was as follows: P-gp+MRP, 41.6% ; P-gp+LRP, 35.0%; MRP+LRP, 53.3%; MRP+GST-π, 50.0%; LRP+GST-π, 58.3%; P-gp+GST-π, 45.0%; P-gp+MRP+LRP+GST-π, 20.0%. Among them, a relationship was detected between P-gp and MRP ( rs =0.756, P < 0.01), between P-gp and LRP ( rs =0.686, P < 0.01), between MRP and LRP ( rs =0.669, P < 0.01), between MRP and GST-π( rs =0.546, P < 0.01), between LRP and GST-π ( rs =0.848, P < 0.01), between P-gp and LRP ( rs =0.689, P < 0.01), and between P-gp and GST-π ( rs = 0.535 , P < 0.01).

CONCLUSIONSThe MDR in lung cancer patients is affected by various multidrug resistance factors. The drug resistance factors' expression is related to histology, but not to TNM stage and cell differentiation.