Sanyang Xuedai enhances the radiosensitivity of human non-small cell lung cancer cells via increasing iNOS/NO production.

OBJECTIVE

In this research, we aimed at finding out how San Yang Xue Dai (SYKT) promotes the radiosensitivity of non-small cell lung cancer (NSCLC) cell line NCI-H460.

METHODS

Survival rate of NSCLC cells (A549, NCI-H460, NCI-H1650 and NCI-H1975) after the SYKT treatment or irradiation (IR) was calculated by the MTT assay. The radiosensitization of SYKT (0.5 g/mL and 1.0 g/mL) on cell line NCI-H460 and the radioresistant cell line NCI-H460R was studied by MTT assay and clone formation assay. The protein expression levels of iNOS, Cyclin B1 and CDC2 were determined by western blot, and the expression of NO was measured by Griess method. Finally, cell cycle and apoptotic rate of NSCLC cell line NCI-H460 were accessed by flow cytometry assay. BrdU staining was also applied to detect the cell proliferation after IR with or without SYKT treatment.

RESULTS

The IC value of SYKT for NCI-H460 cells was 1.03 g/mL. After 1.0 g/mL SYKT treatment, the radiosensitivity of NCI-H460R cells was enhanced. The level of iNOS in the cells was found decreased after IR. We also found that SYKT could enhance iNOS and NO expressions while inhibit cyclin B1 and CDC2 expressions in radiation resistant cells. Combining β-irradiation with SYKT caused cell cycle arrest in G2/M phase and increased cell apoptosis.

CONCLUSION

SYKT resensitized radioresistant NCI-H460R cells via increasing cell apoptosis and cell cycle arrest. This was due to an elevated NO level caused by accumulating iNOS and effects of SYKT on radiosensitization of NSCLC should be further investigated in clinical application.