Combined effect of cisplatin and 5-fluorouracil with irradiation on tumor cells in vitro

The concomitant administration of chemotherapy and radiation is an alternative tool in cancer therapy. The antiproliferative and the radiosensitizing effect of Cisplatin and 5-Fluorouracil (5-FU) were studied on mouse lymphoma cells transfected with human MDR1 gene (mdr) and its parent cell line (par) combined with and without radiation. HEp2 radioresistant cell culture was used in our experiments as a model of radioresistance. The growth rate and antiproliferative effect was measured by the MTT method. Significant inhibition of tumor cell growth was observed at a low concentration of Cisplatin and 5-FU combined with radiation on the mouse lymphoma cell lines. However an extremely high dose of Cisplatin and 5-FU resulted in moderate growth inhibition in the case of the HEp2 cell line. We assume that the radiosensitizing effect of 5-FU and Cisplatin can be considered as a synergistic antitumor effect at low doses of chemotherapy and radiation in a radiosensitive cell line. In the case of a radio-and chemoresistant cell line, high doses of radiation and chemotherapeutic agent achieved moderate tumour growth inhibition without significant synergistic effect. In addition the simultaneous application of both treatments can result in remarkable toxicity.