ING4抑制N-甲基-N-硝基-N-亚硝基胍诱导的胃癌血管生成及其分子机制

Gastric cancer is the malignancy which endangers human health severely. N-nitroso compounds (NOCs) which exist in the environment are important causes for the tumorigenesis and progression of gastric cancer, but the mechanism isn’t fully elaborate. A study has reported that methylnitronitrosoguanidine (MNNG, one of NOCs) induced obvious angiogenesis in rat gastric cancer tissues, and in our study, we found that the conditional supernatant which was collected from the gastric cancer cells stimulated by MNNG promoted the vascular endothelial cell tube formation, these results suggested that MNNG could accelerate gastric cancer progression through inducing gastric cancer angiogenesis. Inhibitor of growth protein 4 (ING4) is an important molecule in inhibiting tumor angiogenesis, we found that MNNG could dramatically reduce the expression of ING4, and over-expression ING4 significantly inhibited the gastric cancer angiogenesis which was induced by MNNG, these results indicated that ING4 was a key molecule in gastric cancer angiogenesis induced by MNNG. .This study includes: (1) The cell and animal models will be used to validate that ING4 can inhibit gastric cancer angiogenesis induced by MNNG; (2) The exact mechanism of ING4 inhibiting gastric cancer angiogenesis induced by MNNG will be illustrated, and the changes of VEGF, MMP-2, and MMP-9 expression and their same upstream, NF-κB signal will be tested. The further study will provide theoretical basis for making interventions against NOCs for gastric cancer, preventing and slowing down the progression of gastric cancer.

胃癌是严重危害人类健康的恶性肿瘤。环境中的N-亚硝基化合物（NOCs）是胃癌发生发展重要诱因，然而其作用机制尚未阐明。研究报道N-甲基-N-硝基-N-亚硝基胍（MNNG，NOCs的一种）能诱导大鼠胃癌组织血管生成，我们也发现MNNG刺激胃癌细胞后，其条件上清明显促进血管内皮细胞管状形成，提示MNNG能诱导血管生成从而促进胃癌进展。生长抑制因子4（ING4）是抑制肿瘤血管生成重要分子，我们发现MNNG能抑制胃癌细胞ING4表达，而过表达ING4能显著抑制MNNG诱导胃癌血管生成，提示ING4是MNNG诱导胃癌血管生成重要分子。.研究包括：（1）细胞及动物模型验证ING4抑制MNNG诱导胃癌血管生成；（2）阐明ING4抑制MNNG诱导胃癌血管生成的分子机制，检测VEGF、MMP-2、MMP-9及其共同上游NF-κB信号通路变化。本研究将为针对NOCs的胃癌干预、预防和减缓胃癌进展提供理论依据。

背景 胃癌是世界范围内发病率与死亡率较高的消化道恶性肿瘤之一。流行病学已经展示长期的N-亚硝基化合物（NOCs）暴露显著地增加了胃癌的死亡率。而血管生成是胃癌进展的关键步骤。因此，为了继续降低胃癌的死亡率，要求我们探索NOCs诱导胃癌血管生成的分子机制。抑癌基因ING4在病理性的血管生成中发挥了重要作用，因此在本研究中，我们将研究ING4对MNNG诱导的胃癌血管生成的抑制作用及分子机制。.内容 （1）研究ING4对MNNG诱导的胃癌血管生成的抑制作用；（2）研究ING4通过抑制p65/VEGF、MMP-2、MMP-9通路，进而抑制MNNG诱导的胃癌血管生成，初步阐明MNNG通过抑制ING4促进胃癌血管生成的分子机制。.结果（1）与平行的0.1%DMSO组相比，低剂量MNNG刺激GES-1细胞60代后发生了恶性转化，且ING4表达随MNNG刺激时间不断降低，尤其在恶转最后阶段，表达量最低；（2）MNNG恶性转化的细胞及MNNG刺激的胃癌细胞的上清液显著增加了血管生成，而ING4过表达显著抑制了这种增加；（3）MNNG诱导了MMP-2及MMP-9的表达，而ING4抑制了其高表达；（4）MNNG诱导的ING4低表达增加了NF-κB p65磷酸化水平及后续DNA绑定能力与促血管生成因子MMP-2、MMP-9的表达，而过表达ING4抑制了这种增高，而且p65过表达废止了ING4所抑制的MMP-2、MMP-9表达及血管生成。.结论 长期低剂量MNNG刺激降低了ING4表达进而激活NF-κB p65信号通路增加血管生成。这一研究可能对我们了解NOCs在胃癌发展中的作用提供新的视角，对制定科学的胃癌干预策略及预防、减缓胃癌的进展和改善患者预后具有非常重要的理论意义和实用价值。