Studies on effect of hypoxia inducible factor on cell adhesion

细胞黏附分子参与了多种疾病的病理生理过程。前段时间，我们一直致力于细胞黏附分子在恶性疾病中的功能意义的研究。在研究过程中，我们注意到在低氧条件下培养的细胞表现出很强的细胞黏附活性。对低氧条件的反应涉及除癌症以外的多种疾病的病理生理学，如糖尿病、肾脏疾病、动脉硬化、缺血性心脏病和器官移植。众所周知，这些疾病也与细胞黏附分子密切相关。在本项目中，我们研究了在低氧条件下促进细胞黏附的机制。我们利用DNA芯片和RT-PCR技术研究了低氧条件下培养的人细胞的基因表达，特别是具有细胞黏附活性的细胞黏附分子和碳水化合物决定子。Hy…更多的低氧培养诱导结肠癌细胞表面选择素配体sialyl Lewis x和sialyl Lewis a决定子的表达显著增加，这导致癌细胞与内皮E-选择素的粘附性明显增加。低氧培养显著诱导癌细胞中参与合成E-选择素碳水化合物配体的基因FUT7、ST3O和UGT1的转录。此外，还检测到Syndecan-4(SDC4)和α5-整合素(ITGA5)基因的显著诱导，这两种细胞黏附分子参与了癌细胞与纤维连接蛋白之间黏附的增强。在荧光素酶报告分析中，这些基因在低氧诱导下的转录诱导被复制，这些基因被显性-阴性形式的HIF显著抑制。这些结果表明，部分由HIF介导的癌细胞的代谢转变显著地增强了它们与血管内皮细胞的黏附，这是通过选择素和整合素介导的途径实现的。较少

Cell adhesion molecules are involved in the pathophysiology of various disorders. Some time ago, we had been engaged with the investigation of functional significance of cell adhesion molecules in malignant disorders. During the study, we had noticed that cells cultured under hypoxic conditions exhibit a strong cell adhesive activity. Response to hypoxic conditions is involved in the pathophysiology of wide variety of disorders other than cancers, such as diabetes, kidney diseases, arteriosclerosis, ischemic heart diseases and organ transplantation. These disorders are known to be closely related also to cell adhesion molecules. In this project we had investigated the mechanism involved in the enhancement of cell adhesion under hypoxic conditions. We investigated gene expression in cultured human cells induced by hypoxic conditions with special reference to cell adhesion molecules and carbohydrate determinants having cell adhesive activity using DNA microarray and RT-PCR techniques. Hy … More poxic culture of colon cancer cells induced a marked increase in expression of selectin ligands, the sialyl Lewis x and sialyl Lewis a determinants at the cell surface, and this led to a definite increase in cancer cell adhesion to endothelial E-selectin The transcription of genes for FUT7,ST3O and UGT1,which are all known to be involved in the synthesis of the carbohydrate ligands for E-selectin, was significantly induced in cancer cells by hypoxic culture. In addition, a remarkable induction was detected in the genes for syndecan-4(SDC4) and α5-integrin (ITGA5), the cell adhesion molecules involved in the enhanced adhesion of cancer cells to fibronectin. The transcriptional induction by hypoxia was reproduced in the luciferase reporter assays for these genes, which were significantly suppressed by the ortransfection of a dominant-negative form of HIF. These results indicate that the metabolic shifts of cancer cells partly mediated by HIFs significantly enhance their adhesion to vascular endothelial cells, through both selectin- and integrin-mediated pathways. Less