Abstract 3373: TGF-β1 signaling mediated lymphangiogenesis in gastric cancer

Abstract

Abstract Background Recent evidence showed that Transforming growth factor (TGF)-β1 could have important role for gastric cancer progression and metastasis. However, the role of TGF- β1 for lymph node metastasis and lymphangiogenesis, the important steps of gastric cancer progression, is largely unknown. To investigate the role of TGF-β1 on lymphangiogenesis and its molecular mechanisms is the main purpose of this study. Methods We selected two gastric cancer cell-line models, MKN45 and KATOIII, which hold appropriate characteristics for the current study. We checked the possibility of the autocrine function of TGF-β1 for lymphangiogenesis in these gastric cancer cell-lines. We investigated the changes of TGF-β1 signaling molecules and VEGF-C expression in responding to TGF-β1 and its inhibitor. To examine the binding of Smad3 to the promoter region of VEGF-C, we performed electrophoretic mobility shift assay (EMSA). Both Smad-dependent and Smad-independent pathways were also examined to elucidate which pathways were involved in lymphangiogenesis. Finally, tube forming assay was performed to validate phenotypical effect of TGF-β1 on lymphangiogenesis. Results Two gastric cancer cell-line models, MKN45 and KATOIII, showed autocrine regulation of TGF-β1. TGF-β1 signaling was transduced to VEGF-C, mediated by Smad3. Smad3 was bound to the promoter of VEGF-C which was confirmed with EMSA. Based on EMSA results, KATOIII showed stronger reaction between Smad3 and VEGF-C promoter than MKN45 did. In MKN45, TGF-β1 also transduced its signal to VEGF-C through PI3k-Akt pathway, one of the Smad-independent pathway. Lymphatic endothelial cells cultured in the condition media of MKN45 and KATOIII underwent tubule structure formation. The growth of HLEC was accelerated with TGF-β1 mixed conditioned media, while failed to induce tubular structure in the presence of TGF-β1 inhibitor. The expression level of secreted VEGF-C was as same in responding to TGF-β1 and its inhibitor as the lymphatic tube forming results in gastric cancer cells. Conclusion TGF-β1 could promote lymphangiogenesis through VEGF-C expression in gastric cancer cell line models. TGF-β1 signaling could be transduced through either Smad-mediated or non- Smad-mediated depending on gastric cancer cell-line characteristics. Citation Format: Kyung Ho Pak, Jae-Ho Cheong, Ki Chung Park. TGF-β1 signaling mediated lymphangiogenesis in gastric cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3373.