Department of Surgery, Hallym University Medical Center, Hwasung, Korea.
Department of Medicine, Yonsei University Graduate School, Seoul, Korea.
BMC Cancer. 2019 Aug 13;19(1):799. doi: 10.1186/s12885-019-5972-y.
The role of TGF-β1 in lymph node metastasis and lymphangiogenesis, one of the most important steps of gastric cancer dissemination, is largely unknown. The goal of this study was to investigate the role of TGF-β1 signaling and its molecular mechanisms involved in lymphangiogenesis of gastric cancer.
Two gastric cell line models, MKN45 and KATOIII, were selected for this study. The protein expression of TGF-β1 pathway molecules and VEGF-C were examined with western blot, or ELISA according to TGF-β1 treatment. To explore whether Smad3 binds to the specific DNA sequences in the VEGFC promoter, we performed an electrophoretic mobility shift assay. Lymphatic tube forming assay and gastric cancer xenograft mouse models were also used to elucidate the effect of TGF-β1 on lymphangiogenesis.
TGF-β1 induced the activation of Smad2/3 and Smad pathway-modulated VEGF-C expression in gastric cancer cell line models. Phosphorylated and activated Smad3 in the nucleus bound to the promoter of VEGFC in KATO III cells. Of note, in MKN45 cells, the Smad-independent AKT pathway was also activated in response to TGF-β1 and induced VEGF-C expression. Inhibition of TGF-β1 signaling down-regulated the expression of VEGF-C. We also confirmed, through tube forming assay and tumor xenograft mouse model, that TGF-β1 increased lymphatic formation, while TGF-β1 inhibition blocked lymphangiogenesis.
Smad-dependent and -independent TGF-β1 pathways induce VEGF-C, which make lymphangiogenesis around tumor. These findings suggest that TGF-β might be a potential therapeutic target for preventing gastric cancer progression and dissemination.
TGF-β1 在淋巴结转移和淋巴管生成中的作用——胃癌扩散最重要的步骤之一，很大程度上仍不清楚。本研究旨在探讨 TGF-β1 信号通路及其在胃癌淋巴管生成中涉及的分子机制。
选择两种胃细胞系模型 MKN45 和 KATOIII 进行本研究。用 Western blot 或 ELISA 根据 TGF-β1 处理检测 TGF-β1 通路分子和 VEGF-C 的蛋白表达。为了探究 Smad3 是否与 VEGFC 启动子中的特定 DNA 序列结合，我们进行了电泳迁移率变动分析。淋巴管生成分析和胃癌异种移植小鼠模型也用于阐明 TGF-β1 对淋巴管生成的影响。
TGF-β1 诱导胃癌细胞系模型中 Smad2/3 的激活和 Smad 通路调节的 VEGF-C 表达。磷酸化和激活的核内 Smad3 与 KATO III 细胞中 VEGFC 的启动子结合。值得注意的是，在 MKN45 细胞中，TGF-β1 还激活了 Smad 非依赖性 AKT 通路，并诱导 VEGF-C 表达。抑制 TGF-β1 信号通路下调了 VEGF-C 的表达。我们还通过管形成分析和肿瘤异种移植小鼠模型证实，TGF-β1 增加了淋巴管形成，而 TGF-β1 抑制则阻断了淋巴管生成。
Smad 依赖性和非依赖性 TGF-β1 通路诱导 VEGF-C，从而促进肿瘤周围的淋巴管生成。这些发现表明 TGF-β 可能是预防胃癌进展和扩散的潜在治疗靶点。
