Biological Effect of Irradiation on Adhesion Molecules in Human Colon Cancer Cells and Application to Clinical Medicine

目前，人们普遍认为某些细胞粘附分子在癌症转移中起着关键作用。循环癌细胞与血管内皮的粘附是癌症血行转移的重要步骤。糖类抗原，如唾液酸刘易斯^a抗原（s-Le^a）和唾液酸刘易斯^x抗原（s-Le^x），在体外和体内癌症转移中起重要作用。特别是s-Le^a在向肝的转移中起重要作用。目前，术前放射治疗用于预防直肠癌局部复发。本研究采用流式细胞术检测了4种人结肠癌细胞株在X射线照射后24 h细胞表面糖抗原s-Le ^a和s-Le ^x的表达，观察了X射线对糖抗原s-Le ^a和s-Le ^x的影响。应用单层细胞粘附实验检测了人脐静脉内皮细胞（HUVECs）的s-Le^a和s-Le^x功能，结果表明，HT 29和WiDr细胞在任何剂量照射后24小时s-Le^a的表达均显著降低。X射线照射可显著降低HT 29和WiDr细胞与HUVECs的粘附能力，提示X射线照射可减少结肠癌肝转移。

Nowadays, it is commonly believed that certain cell adhesion molecules play critical roles in cancer metastasis. The adhesion of circulating cancer cells to the vascular endothelium is an important step in the hematogenous metastasis of cancer. Carbohydrate antigens, such as sialyl Lewis^a antigen ( s-Le^a) and sialyl Lewis^x antigen ( s-Le^x), play an important role in cancer metastasis in vitro and in vivo. Especially s-Le^a plays an important role in metastasis to the liver. Currently, preoperative radiotherapy is used for preventing local recurrence of rectal cancer. We investigated the effects of X-ray irradiation on carbohydrate antigens s-Le^a and s-Le^x in vitro.The cell surface expressions of s-Le^a and s-Le^x were determined by flow cytometric analysis at 24 hours after X-ray irradiation of 4 human colon cancer cell lines. s-Le^a and s-Le^x functions were quantitated using a monolayer cell adhesion assay with human umbilical vein endothelial cells ( HUVECs).In this study the expression of s-Le^a decreased significantly at 24 hours after any dose of irradiation in HT 29 and WiDr cells. And X-ray irradiation significantly decreased the cell adhesion capacity of HT 29 and WiDr cells to the HUVECs.These results may indicate the possibility of a reduction of liver metastasis in colon cancer using X-ray irradiation.