Objective: To explore the role of p53 mutation in the development of acquired multi-drug resistance during lung cancer chemotherapy.
Methods: A resistance large cell lung carcinoma cell line (H460/DDP) was established by high dose (50 micromol/L) cisplatin intermittent selection from its parental cell NCI-H460 that had wild type p53 (wtp53). Several multi-drug resistant proteins (MRP) including lung relative protein (LRP), P-gp, MRP, glutathione transferase-pi, topoisomerase II and P53 were checked by immunocytochemistry. Immunofluorescence was used to check the phosphoration of P53. p53 cDNA was amplified and sequenced. The H460/DDP cells were transected with plasmid pShuttle-CMV-wtp53 cDNA and measurement of drug sensitivity was performed after transfection.
Results: The resistance index to cisplatin and carboplatin in H460/DDP cell line was 10.21 and 9.98 respectively, and the cell line also exhibited cross-resistance to 5-fluorouracil, etoposide, methotrexate, adriamycin, epirubicin, bleomycin and novantrone, except for taxol. It was found that P53 protein translocated from nuclear to cytoplasm and could not phosphorate after the stimulation of cisplatin. LRP was expressed increasingly and other proteins showed insignificant changes. Sequencing showed an important insertion "t" after 277 bp on the gene level. H460/DDP cells transfected with plasmid pShuttle-CMV-wtp53 cDNA reversed partly (53.2%) the resistance to cisplatin/carboplatin, compared to the H460/DDP cells transfected with blank vector.
Conclusions: p53 mutation induced by cisplatin/carboplatin might play an important role in the development of acquired multi-drug resistance of lung cancer chemotherapy. wtp53 substitute therapy during chemotherapy may be an effective method to overcome the acquired drug resistance.