It has recently been recognized that inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), upregulate the secretion of matrix metalloproteinase-9 (MMP-9) from cancer cells and thereby promote peritoneal dissemination. In this study, we found that TNF-α also stimulated peritoneal mesothelial cells to secrete MMP-9 as assessed by zymography. MMP-9 gene expression in mesothelial cells induced by TNF-α was confirmed by quantitative RT-PCR analysis. We then utilized the reconstituted artificial mesothelium, which was composed of a monolayer of mesothelial cells cultured on a Matrigel layer in a Boyden chamber system, to examine the effects of TNF-α on carcinoma cell invasion. The transmigration of MKN1 human gastric carcinoma cells through the reconstituted mesothelium was promoted by TNF-α in a dose-dependent manner. The increased MKN1 cell migration was partially inhibited by the anti-α3 integrin antibody, indicating that the invasion process involves an integrin-dependent mechanism. Finally, we observed that the invasion of MMP-9-knockdown MKN1 cells into Matrigel membranes was potentiated by the exogenous addition of purified proMMP-9. These results suggest that TNF-α-induced MMP-9 secretion from mesothelial cells plays an important role in the metastatic dissemination of gastric cancer.

中文翻译：

---

TNF-α刺激腹膜间皮细胞分泌基质金属蛋白酶9（MMP-9）：在胃癌细胞侵袭中的作用

最近已经认识到，诸如肿瘤坏死因子-α（TNF-α）之类的炎性细胞因子上调了癌细胞中基质金属蛋白酶-9（MMP-9）的分泌，从而促进了腹膜的扩散。在这项研究中，我们发现TNF-α还可以刺激腹膜间皮细胞分泌MMP-9（如酶谱分析所示）。通过定量RT-PCR分析证实了TNF-α诱导的间皮细胞中MMP-9基因的表达。然后，我们利用重构的人造间皮（由在Boyden腔系统中的基质胶层上培养的单层间皮细胞组成）来检查TNF-α对癌细胞侵袭的影响。TNF-α以剂量依赖的方式促进MKN1人胃癌细胞通过重构的间皮细胞的迁移。增加的MKN1细胞迁移被抗α3整联蛋白抗体部分抑制，表明入侵过程涉及整联蛋白依赖性机制。最后，我们观察到，通过外源添加纯化的proMMP-9，可以增强MMP-9抑制型MKN1细胞侵袭Matrigel膜的能力。这些结果表明，TNF-α诱导的间皮细胞分泌MMP-9在胃癌的转移扩散中起重要作用。