Gamma-secretase inhibitor does not modulate angiogenesis in colon adenocarcinoma in obese mice.

Background: Notch is a signaling molecule which plays a role in angiogenesis and γ-secretase is required for processing of Notch. In this study, we investigated the effect of γ-secretase inhibitor (DAPT) on tumor angiogenesis in diet-induced obese mice.
Methods: 18 mice were divided into three groups; control, obese (diet-induced) and obese+DAPT. After 15 weeks, the obese mice were subjected for tumor induction of CT26 colon adenocarcinoma cells (5 x 105 cells). When the tumor size reached approximately 350 ± 50 mm3, half of the obese animals received DAPT (10mg/kg/day) subcutaneously. Blood samples were taken after 14 days and the tumors harvested for immunohistochemical staining and capillary density were reported as CD31 positive cells/mm2.
Results: The obese animals had higher serum leptin and NO concentrations, while, serum VEGF and VEGFR-1 concentrations were not different compare to control group. Administration of DAPT in obese mice significantly reduced serum VEGFR-1 and leptin concentrations and increased serum NO level (p < 0.05). Capillary density in the tumors of obese animals was not different compare to control groups. DAPT administration could not alter capillary density in the tumors.
Conclusion: Administration of DAPT in obese mice altered serum angiogenic factors, however, it could not modulate tumor angiogenesis in diet-induced obese mice (Fig. 4, Ref. 26).