ABSTRACT
Background: The family of curcumin has biological functions, such as anti-oxidative and anti-inflammatory action. Recently, its inhibitory effect on angiogenesis in tumor has been suggested. However, it is not clear how curcumin (CUR) or its derivatives have such in vivo effects. Objective: To quantitatively examine the in vivo effects of CUR or its reduced derivative, tetrahydrocurcumin (THC), on neocapillarization in nude mouse tumors induced by hepatocellular carcinoma (HepG2) cells. Methods: In male BALB/c nude mice (20-25g b.w.), a dorsal skin-fold chamber was implanted, and 30 ml of 2 x 10⁶ human HepG2 cells were inoculated onto the upper layer. The mice were divided into 4 groups: control (CON) supplemented with 0.1% DMSO, HepG2-implanted mice supplemented with DMSO, CUR or THC groups supplemented with CUR or THC (3,000 mg/kg bw), respectively. On the day of the experiment, days 7 and 14, the microcirculation within the chamber was observed using fluorescence videomicroscopy. Based on the recorded video images, capillary vascularity (CV) was measured on the tumor surface. Results: The CV increased in tumors on days 7 and 14 in the HepG2-implanted mice. In the CUR and THC groups, the CV levels were lower than the control level. Furthermore, on day 14, the CV level of THC group was lower than the CV level of the age-matched group. This indicates that HepG2-induced neocapilllaries were reduced markedly by supplementation of THC. Conclusion: THC is potent for suppression of neocapillarization involved in tumor progression.