Prediction of 5-fluorouracil and cisplatin synergism for advanced gastrointestinal cancers using a collagen gel droplet embedded culture.

Abstract

The combination effects of 5-fluorouracil (5-FU) and cisplatin (CDDP) are herein reported using a drug sensitivity assay, with a special focus on the induction of apoptosis. The combination effects of 5-FU and CDDP were examined using in vitro chemosensitivity testing by means of the collagen gel droplet embedded culture drug sensitivity test (CD-DST) in MKN45 and GSS cell lines, and primary gastrointestinal cancer cells ob-tained from 40 patients. Apoptosis was assayed using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin neck end labeling (TUNEL) method. The combination of 5-FU with CDDP increased the efficacy of 5-FU 1.16-1.35-fold with the GSS cell line and 1.10-2.01-fold with primary gastric and colorectal cancers when the exposure time was 7 days. In primary tumor cells a synergistic action was noted in 15 of 40 (38%) gastric and colorectal cancers. Both 5-FU and CDDP were found to induce apoptosis in GSS and MKN45 cells, and the number of apoptotic cells increased synergistically after the combined treatment in the GSS cases and showed a correlation with the results of CD-DST. Our findings suggested that the efficacy of the combined treatment with 5-FU and CDDP can be predicted by the in vitro chemosensitivity test and that a synergistic effect might be associated with the induction of apoptosis.