Cytocidal effect of cisplatin and its derivatives with combination of X-ray irradiation

To see in what extent cisplatin derivatives enhanced the effect of X-ray, human squamous cells, PC-1 cells, and human lung adenocarcinoma cells, PC-3 cells, were irradiated with 2-10 Gy of X-ray. Drugs were CDDP, CBDCA and 254-S, which were exposed at 6-150 μM to cells for 1 hr each before and after irradiation under the aerobic or anaerobic condition. Cells after treatments were assayed for their vitality by colony formation. Synergetic effect of cisplatin derivatives and X-ray was not seen in PC-1 cells under any conditions, whereas, in PC-3 cells, the effect was observed under the anaerobic condition. Cisplatin was thus found most suitable for combination therapy with X-ray. (K.H.)