Abstract
1713
Objectives To investigate the effect of irradiation on multidrug resistance (MDR) in non-small lung cancer cells.
Methods A non-small-cell lung cancer cell strain (H1299) was cultured after irradiation (3, 6, 9, 12 Gy irradiated groups - Irrs) along with two controls (no irradiation group - C) with and without MDR inhibitor (verapamil group - Vrp), respectively. After addition of Tc-99m MIBI (MIBI), we measured the radioactivity of the cells, due to the accumulation and efflux of MIBI, in a gamma well counter and calculated of the Cin/Cout ratio. The same cells were transplanted to the ICR nu/nu mouse and was then grown for two weeks. MIBI was administered in the tail veins of the mice, the no-irradiation mouse (C-m) and the 9 Gy irradiated mouse (Irr-m). MIBI accumulation at the tumor region was measured using a gamma camera. Addition of doxorubicin (DOX), by an analogous method, measured mean fluorescence (MF) of the cells in flow cytometry and fluorescence imaging was used to measure photon counts (PCs) of the tumor in vivo imaging system.
Results The Irrs exhibited higher ratios in proportion to radiation dose than the C. In comparison with the C, the higher Cin/Cout ratios of the 9 and 12 Gy Irrs (p<0.05, Table-1). In efflux study, at 30 minutes, the lower efflux rate for all Irrs and the Vrp in comparison with the C. The Irr-m tumors exhibited more than seven times mean MIBI accumulation, after 30 minutes, than the C-m tumors. The DOX MF and PCs exhibited a similar trends as MIBI (Figure-1).
Conclusions Irradiation decreases MDR in non-small lung cancers cells