TGFβ Suppresses Physiological Angiogenesis But Not Tumor Angiogenesis: A Study in Zebrafish and Mouse Models

We initially investigated the impact of TGFβ on tumor angiogenesis using a mouse xenograft model. Two murine hepatoma cell lines, Hepa-TGFβ and LC-Rd53-TGFβ, with stable TGFβ expression (Supplementary Fig. 1A), and their control lines, Hepa-Ctrl and LC-Rd53-Ctrl, were subcutaneously injected into mice. Interestingly, we observed no significant differences in microvessel area, microvessel density, or tumor growth between control xenografts and TGFβ-overexpressing tumors (Fig. A–D, Supplementary Fig. 1A–E), suggesting that TGFβ may not suppress tumor angiogenesis. Next, we examined the role of TGFβ in physiological angiogenesis using a Tg(fli1:EGFP) transgenic zebrafish model, in which endothelial cells (EC) were specifically labeled with green fluorescence. Zebrafishes with stable TGFβ expression exhibited a significant decrease in subintestinal vessel (SIV) area, a crucial indicator of zebrafish angiogenesis, compared to the control group (Supplementary Fig. 1F, G, Fig. 1E, F). However, overexpression of TGFβ did not affect zebrafish growth (Supplementary Fig. 1G, H), suggesting that TGFβ may suppress physiological angiogenesis but not tumor angiogenesis in vivo.

Further analysis of the transcriptome profile showed that TGFβ signaling molecules were significantly down-regulated in tumor EC (TEC) isolated from HCC tissues, compared to non-tumor EC (NEC) from adjacent non-tumor livers (Fig. 1G), implying that the TGFβ pathway may be inactivated in TEC.