RT Journal Article SR Electronic T1 Interaction of Radiation and Pemetrexed on a Human Malignant Mesothelioma Cell Line In Vitro JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 2847 OP 2851 VO 31 IS 9 A1 DAISAKU YOSHIDA A1 TAKESHI EBARA A1 YUMI SATO A1 TAKUYA KAMINUMA A1 TAKEO TAKAHASHI A1 TAKAYUKI ASAO A1 TAKASHI NAKANO YR 2011 UL http://ar.iiarjournals.org/content/31/9/2847.abstract AB Purpose: To investigate the interaction of the cytotoxic activity of the combination of pemetrexed and radiation in a human mesothelioma cell line. Materials and Methods: The toxic effects of treatment with radiation and/or pemetrexed (PEM) on NCI-H28 cells were assessed by clonogenic assay. TUNEL/DAPI staining was used to measure the apoptosis index (AI). Thymidylate synthase (TS) protein expression was measured by Western blotting. Results: The D0 value of the combination treatment was lower than that for radiation, indicating its addition resulted in the synergistic effects with radiation. An increase in AI was observed with the combination compared with that observed after PEM alone. Radiation induced a time-dependent decrease in TS expression. Increased TS expression was observed after PEM, but the combination treatment decreased TS expression. Conclusion: Treatment with pemetrexed in combination with radiation has a supra-additive effect, partially due to the synergistic induction of apoptosis, which may be due to TS suppression, by the irradiation enhancing the effect of pemetrexed.