Department of Surgery, Saga University Faculty of Medicine, Saga 849-8501, Japan.
Int J Oncol. 2013 Nov;43(5):1431-40. doi: 10.3892/ijo.2013.2068. Epub 2013 Aug 21.
The molecular mechanisms underlying the peritoneal dissemination of gastric cancer remain unclear. Using in vivo metastatic models, this study attempted to clarify the role of hypoxia inducible factor (HIF)-1α in the development of peritoneal dissemination of gastric cancer. HIF-1α knockdown (KD) cells were established in the scirrhous gastric cancer cell line 58As9. Using KD and control (SC) cells, the presence of peritoneal dissemination was assessed in orthotopic implantation (o.i.) and intraperitoneal injection (i.p.) models. A series of in vitro analyses were also conducted. Finally, tumor angiogenesis was immunohistochemically analyzed. In the o.i. model, peritoneal dissemination was more frequently observed in the SC mice (93%) compared to the KD mice (13%) (P<0.001). In the i.p. model, peritoneal dissemination occurred at a high rate in both types of mice; however, a greater number of nodules was observed in the KD mice (P=0.017). The in vitro assays showed that HIF-1α exerts unfavorable effects on anoikis resistance and adhesion to extracellular matrix. Angiogenesis and vascular invasion were more aggressive in the SC gastric tumors. Vascular invasion was present in the intratumoral regions of the disseminated nodules in the SC o.i., but not the i.p., mice. HIF-1α was found to be crucial for the development of peritoneal dissemination in o.i. model, which mimics natural metastasis. In contrast, HIF-1α played an inhibitory role in suppressing peritoneal dissemination in the i.p. model. These results indicate that peritoneal dissemination in o.i. mice may not act through a seeding mechanism. An immunohistochemical analysis demonstrated HIF-1α-activated angiogenesis and vascular invasion in stomach tumors. Furthermore, the results showed that the disseminated nodules observed in SC o.i. mice were formed via extravasation of cancer cells. We provide a possible mechanism in which peritoneal dissemination of gastric cancer develops via a vascular network whereby HIF-1α activates tumor angiogenesis.
胃癌腹膜转移的分子机制尚不清楚。本研究通过体内转移模型，试图阐明缺氧诱导因子（HIF）-1α在胃癌腹膜转移发展中的作用。在硬癌胃癌细胞系 58As9 中建立了 HIF-1α 敲低（KD）细胞。使用 KD 和对照（SC）细胞，在原位植入（o.i.）和腹腔内注射（i.p.）模型中评估腹膜转移的存在。还进行了一系列体外分析。最后，通过免疫组织化学分析肿瘤血管生成。在 o.i.模型中，SC 小鼠（93%）腹膜转移的发生率高于 KD 小鼠（13%）（P<0.001）。在 i.p.模型中，两种类型的小鼠均发生高腹膜转移率，但 KD 小鼠的结节数量更多（P=0.017）。体外试验表明，HIF-1α对无锚定生存能力和细胞与细胞外基质的黏附产生不利影响。SC 胃肿瘤的血管生成和血管侵袭更为活跃。血管侵袭在 SC 原位肿瘤的播散结节的肿瘤内区域存在，但在 i.p.小鼠中不存在。HIF-1α对于模拟自然转移的 o.i.模型中腹膜转移的发展至关重要。相反，HIF-1α在 i.p.模型中发挥抑制腹膜转移的作用。这些结果表明，o.i.小鼠中的腹膜转移可能不是通过播种机制起作用。免疫组织化学分析显示，HIF-1α激活了胃肿瘤中的血管生成和血管侵袭。此外，结果表明，在 SC o.i.小鼠中观察到的播散结节是通过癌细胞的血管外渗形成的。我们提供了一种可能的机制，即胃癌腹膜转移通过血管网络发展，其中 HIF-1α激活肿瘤血管生成。
