Molecular mechanisms of peritoneal dissemination of ovarian cancer cell, based on the analysis of its microenvironment

卵巢癌是妇科癌症死亡的主要原因。卵巢癌患者预后不良与腹膜播散有关；癌细胞从原发肿瘤脱离，附着在腹膜上，并在原发肿瘤处重新生长的转移过程。本研究的目的是在分析卵巢癌细胞播散微环境的基础上，探讨卵巢癌细胞腹膜播散的分子机制。恶性腹水或卵巢肿瘤液的pH、pO2和pCO2分析揭示了卵巢癌细胞的缺氧环境。此外，免疫组化对缺氧诱导因子-1 α (HIF-1 α)表达的研究表明，HIF-1 α定位于乳头状突起周围的肿瘤细胞核中。这些发现表明卵巢癌细胞在腹膜播散的初始阶段暴露于缺氧。基因芯片分析表明，hypoxi…More a可下调卵巢癌细胞粘附分子E-cadherin和β -catenin的表达。在卵巢癌组织中，HIF-1 α阳性的肿瘤细胞倾向于失去E-cadherin的表达。Northern blot和Western blot分析还显示，缺氧通过上调E-cadherin的转录抑制因子SNAL，降低了E-cadherin在卵巢癌细胞中的表达。因此，缺氧微环境很可能在癌细胞粘附衰减、向“转移表型”转化过程中发挥了重要作用。我们对卵巢上皮性肿瘤中ras相关GTPases Rho的表达研究发现，与良性肿瘤相比，卵巢癌中ras相关GTPases Rho的表达明显升高。此外，其mRNA和蛋白水平在腹膜播散中的表达明显高于原发病变。溶血磷脂酸（LPA）上调和激活Rho可增加卵巢癌细胞的体外侵袭性，而Rho特异性抑制剂C3外泌酶（C3 exoenzyme）可逆转LPA处理的作用。裸鼠体外模型显示，Rho在组成性表达的卵巢癌细胞中腹腔播散更为突出。这些发现表明，Rho的上调在卵巢癌的肿瘤进展中是必不可少的，并将成为未来治疗的分子靶点。少

Ovarian carcinoma is the leading cause of gynecological cancer death. The poor prognosis for patients with ovarian cancer is related with peritoneal dissemination; a metastatic process in which cancer cells detach from the primary tumor, attach to the peritoneum, and re-grow at the site. The objective of this study is to explore the molecular mechanisms of peritoneal dissemination of ovarian cancer cells, based on the analysis of the microenvironment of disseminating cancer cells.Analysis of pH, pO2 and pCO2 of malignant ascitic or ovarian tumor fluids disclosed hypoxic environment of ovarian cancer cells. In addition, immunohistochemical study on the expression and hypoxia-inducible factor-1 alpha (HIF-1 alpha) showed that HIF-1 alpha is localized in the nuclei of tumor cells at the periphery of papillary projection. These findings indicate that ovarian cancer cells are exposed to hypoxia at the initial step of peritoneal dissemination.cDNA microarray analysis demonstrated that hypoxi … More a down-regulates the expression of cell adhesion molecules, E-cadherin and beta-catenin, in ovarian cancer cells. In ovarian carcinoma tissues, the tumor cells positive for HIF-1 alpha tended to lose E-cadherin expression. Northern blot and Western blot analyses also showed that hypoxia attenuates the expression of E-cadherin in ovarian cancer cells, via up-regulation of SNAL, a transcriptional represser of E-cadherin. Therefore, it is likely that hypoxic microenvironment plays an important role in the attenuation of cell adhesion and transformation into "metastatic phenotype" of cancer cells.Our study on the expression of ras-related GTPases Rho in epithelial ovarian tumors revealed that it was elevated in ovarian carcinomas compared with benign tumors. In addition, its expression at mRNA and protein levels was significantly higher in the peritoneal dissemination than in the primary lesion. Up-regulation and activation of Rho by treatment with lysophospahtidic acid (LPA) increased the in vitro invasiveness of ovarian cancer cells, and treatment with C3 exoenzyme, a specific inhibitor of Rho, reversed the effect of LPA treatment. Ex vivo model using nude mice showed that peritoneal dissemination was more prominent in ovarian cancer cells expressing Rho constitutively. These findings indicate that up-regulation of Rho is essential in the tumor progression of ovarian carcinoma, and will be a molecular target in the future therapy. Less