Interferon-alpha 2a up-regulated thymidine phosphorylase and enhanced antitumor effect of capecitabine on hepatocellular carcinoma in nude mice.

PURPOSE: To investigate the antitumor effect of interferon-alpha 2a (IFN-alpha2a) combined with capecitabine on hepatocellular carcinoma (HCC) in nude mice in relation to thymidine phosphorylase (TP) expression.

METHODS: Thirty nude mice bearing orthotopic xenografts of a human HCC tumor (LCI-D20) were divided into control, capecitabine, IFN-alpha2a, and combination (capecitabine plus IFN-alpha2a) groups. Tumor growth was determined by measuring the tumor volume. An enzyme-linked immunosorbent assay (ELISA) was used to study the TP expression in the cancer tissues of the liver.

RESULTS: IFN-alpha2a enhanced the sensitivity of the LCI-D20 tumor response to capecitabine treatment. The tumor volume was significantly reduced in the capecitabine (455+/-236 mm(3)), IFN-alpha2a (248 +/- 114 mm(3)) or combination (46 +/- 29 mm(3)) treatment groups as compared to the control (1,033 +/- 146 mm(3)) (P < 0.01). A significant difference was also found between the single treatment (capecitabine or interferon) and combination treatment group (P < 0.01 and P < 0.05, respectively). IFN-alpha2a up-regulated TP expression in LCI-D20 tumor. An approximate 1.5-fold increase in TP expression was observed in the mice which received IFN-alpha2a treatment compared to the control mice.

CONCLUSION: IFN-alpha2a enhanced the antitumor effect of capecitabine on HCC in nude mice, which might be ascribed to the up-regulation of TP expression in liver cancer tissues by IFN-alpha2a.