In vitro antitumor activity of TAS-103 against freshly-isolated human colorectal cancer.

DNA topoisomerases (Topo) are enzymes that relieve the secondary twist on the DNA strand in the process of DNA synthesis and transcription; therefore they are unique targeting molecules for the chemotherapy of colorectal cancer. TAS-103 (6-[[2- (dimethylamino)ethyl]amino]-3-hydroxy- 7H-in-deno [2,1-c]quinolin-7-one dihydrochloride, MW; 406.31), a novel quinoline derivative, has recently been established as a Topo I and Topo II inhibitor. The aim of the present study was to investigate the antitumor activity of TAS-103 by the MTT assay in human highly- purified and freshly-isolated colorectal cancer cells. Tu our knowledge, this is the first data concerning the antitumor activity of TAS-103 in highly-purified and isolated human colorectal cancer cells. TAS-103 showed the strongest antitumor activity among the conventional anticancer agents for colorectal cancer (p<0.05). The combination with CDDP augmented the antitumor activity of TAS-103 (p<0.05), indicating that CDDP is one of the most potent candidates to be used in combination with TAS-103. To predict the clinical effect of TAS-103, the expressions of Topo I and Topo II were measured by quantitative PCR. However, a correlation between the expression of Topo and the antitumor activity of TAS-103 was not established. In conclusion, according to this data, TAS-103 may be useful in the chemotherapy of colorectal cancer.