The inhibitory effect of recombinant canstatin on tumor angiogenesis and lymphangiogenesis in a CT-26 colon carcinoma animal model

We describe the effect of recombinant canstatin on suppression of angiogenesis and lymphangiogenesis both in vitro and in vivo. Recombinant canstatin produced from stably transformed Drosophila S2 cells reduced expression of angiopoietin-1 in hypoxia mimetic agent, CoCl₂-treated CT-26 cells. Recombinant canstatin inhibited proliferation, tube formation, and migration of human angiopoietin-1 (rhAngpt-1)-treated human umbilical vein endothelial cells (HUVEC) and lymphatic endothelial cells (LEC). Recombinant canstatin suppressed expression of Tie-2 and vascular endothelial growth factor-3 (VEGFR-3) transcripts in rhAngpt-1-treated HUVEC and LEC, respectively. The inhibitory effect of recombinant canstatin on tumor growth was also investigated using a heterotopic CT-26 colon carcinoma animal (BALB/c mice) model. Recombinant canstatin reduced the final volume and weight of tumors, and blood and lymphatic vessel densities of tumors, which were evaluated after CD-31 and LYVE-1 immunostaining. Immunohistochemical analysis showed that recombinant canstatin dramatically reduced expression of angiopoietin-1 in CT-26 colon carcinoma-induced tumor, but not expression of VEGF-C. Tie-2 and VEGFR-3 expressions were also reduced in recombinant canstatin-treated tumors. These results indicate that recombinant canstatin has anti-tumoral activities against CT-26 colon carcinoma cells. Recombinant canstatin probably inhibits angiogenesis and lymphangiogenesis via suppression of the integrin-dependent FAK signaling induced by angiopoietin-1/Tie-2 and/or VEGFR-3. This study was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology of Korea (2011-0003112).