[Inhibitory effect of human mitochondria-targeted MPG recombinant on proliferation of human non-small cell lung cancer multidrug-resistant cell line A549/DDP].

BACKGROUND & OBJECTIVE: Multidrug resistance is the key obstacle to the improvement of chemotherapy effect of lung cancer. This study was to construct eukaryotic expression vector of human mitochondria-targeted N-methylpurine DNA glycosylase (MPG), and explore its inhibitory effect on proliferation of human non-small cell lung cancer multidrug-resistant cell line A549/DDP.

METHODS

Manganese-superoxide dismutase mitochondria-targeted sequence-MPG fusion gene (mito-MPG) was constructed through splicing by overlap extension (SOE). Recombinant eukaryotic expression vector pCMV-Script/mito-MPG was constructed by molecule-cloning technique, and then transfected into A549/DDP cells. In the stably transfected cells which were screened out by G418, the expression of mito-MPG mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR); its expression in separated and purified mitochondria was detected by Western blot. The proliferation of A549/DDP cells was detected by trypan blue exclusion trial. Cell cycle distribution was analyzed by flow cytometry.

RESULTS

The mito-MPG fusion gene was confirmed by DNA sequencing,the recombinant pCMV-Script/mito-MPG was confirmed by restrictive endonuclease digestion and DNA sequencing. mito-MPG mRNA and protein were detected in the cells transfected with pCMV-Script/mito-MPG (MPG group), but not in the cells transfected with pCMV-Script (P group) and untransfected cells (C group). The cell double time were 72.6 h in C group, 73.5 h in P group, and 98.9 h in MPG group. Cell cycle blockage and subdiploid peak were found in MPG group. The proliferation indexes were 51.3% in C group, 54.3% in P group, and 26.1% in MPG group.

CONCLUSION

pCMV-Script/mito-MPG could be constructed and transfected into mitochondria of A549/DDP cells successfully, and inhibit proliferation and induce apoptosis of A549/DDP cells.