Boonkitticharoen, VLaohathai, KPuribhat, S2009-05-272009-05-271993-05-01Boonkitticharoen V, Laohathai K, Puribhat S. Differential radiosensitization of radioresistant human cancer cells by caffeine. Journal of the Medical Association of Thailand. 1993 May; 76(5): 271-7http://imsear.searo.who.int/handle/123456789/40297Chotmaihet Thangphaet.The effect of caffeine, the methylated xanthine, in sensitizing the lethal action of ionizing radiation in vitro was investigated in human cancer cells which were clinically known to be radioincurable. The tumor lines were hepatocellular carcinoma and colon adenocarcinoma. Plateau phase cultures, after absorbing doses of 2 Gy, survived at a rate of 56.30 per cent for colon cancer and at 66.05 per cent for liver cancer. Both lines were radiosensitized by caffeine but at different potencies. Noteworthily, hepatocellular carcinoma whilst less radiosensitive than colon adenocarcinoma was 4 times more susceptible to caffeine. The lowest effective caffeine concentration for liver cancer was 2 mM which slightly exceeded the anticipated lethal concentration in humans. Research on radiosensitizing effect of methylated xanthines on hepatoma system still remains intriguing. Future work should be pursued with the use of less toxic compounds, such as theobromine.engAdenocarcinoma --radiotherapyCaffeine --pharmacologyCarcinoma, Hepatocellular --radiotherapyColonic Neoplasms --radiotherapyGamma RaysHumansRadiation Tolerance --drug effectsRadiation-Sensitizing Agents --pharmacologyTumor Cells, Cultured --radiation effectsJournal Article