Clinical significance of Kir2.1/KCNJ2 and MRP1/ABCC1 protein expression in small-cell lung cancer

AIM: To investigate the expression of inward rectifying potassium channel 2.1 (Kir2.1/KCNJ2) and multidrug resistance-associated protein 1 (MRP1/ABCC1) in small-cell lung cancer (SCLC), and the correlation between them. METHODS:The mRNA and protein expression of MRP1/ABCC1 and Kir2.1/KCNJ2 in H69 and H69AR cell lines was detected by real-time PCR and Western blotting. Immunohistochemistry (EnVision) method was used to detect the expression of Kir2.1/KCNJ2 and MRP1/ABCC1 proteins in 44 cases of SCLC tissues. The interaction of Kir2.1/KCNJ2 with MRP1/ABCC1 was tested by co-immunoprecipitation (co-IP). RESULTS:The mRNA and protein expression of MRP1/ABCC1 and Kir2.1/KCNJ2 in H69AR cells was all significantly higher than that in H69 cells (P<005). The positive expression rates of Kir2.1/KCNJ2 and MRP1/ABCC1 in the 44 cases of SCLC tissues were 47.7% (21/44) and 52.3% (23/44), respectively. A positive correlation was found between the expression of Kir2.1/KCNJ2 and MRP1/ABCC1 in SCLC tissues (r=0.853, P<0.01). Co-IP results showed that Kir2.1/KCNJ2 could bind MRP1/ABCC1 in H69AR cells. CONCLUSION: Kir2.1/KCNJ2 is related to the multidrug resistance of SCLC. Kir2.1/KCNJ2 and MRP1/ABCC1 may have common function roles. Therefore, Kir2.1/KCNJ2 may promote the multidrug resistance of SCLC by regulating the expression of MRP1/ABCC1.