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肿瘤转移过程中起着关键作用。循环癌细胞与血管内皮的黏附是肿瘤血行转移的重要步骤。碳水化合物抗原，如唾液酸Lewis^a抗原（s-Le^a）和唾液酸Lewis^x抗原（s-Le^x），在体内和体外的肿瘤转移中都起着重要的作用。特别是s-Le^a在肝转移中起重要作用。目前，术前放疗是预防直肠癌局部复发的常用方法。本文研究了x射线辐照对体外碳水化合物抗原s-Le^a和s-Le^x的影响。用流式细胞术测定4株人结肠癌细胞株x射线照射后24小时细胞表面s-Le^a和s-Le^x的表达。采用人脐静脉内皮细胞（HUVECs）单层细胞黏附实验定量s-Le^a和s-Le^x功能。在本研究中，任何剂量辐照后24小时，HT 29和WiDr细胞中s-Le^a的表达均显著降低。x射线照射可显著降低ht29和WiDr细胞对huvec的粘附能力。这些结果可能提示使用x射线照射减少结肠癌肝转移的可能性。

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.