衣霉素对人肝癌细胞表面胰岛素受体的影响

Effect of Tunicamycin on the Insulin Receptor on the Surface of Human Hepatocarcinoma Cell Line SMMC-7721

衣霉素是一种糖蛋白Ｎ－连接型糖链合成的抑制剂。它可抑制人肝癌细胞株ＳＭＭＣ－７７２１的生长，其抑制率和剂量及处理时间有相关性。衣霉素处理细胞１８ｈ尚可显著抑制＾３Ｈ－亮氨酸的参入。这些标记化合物的参入抑制都有量效关系。０．１μｇ／ｍＬ衣霉素处理１８ｈ后，细胞表面胰岛素受体和胰岛素的结合容量下降，而对照细胞和处理细胞的胰岛素竞争结合曲线基本平行。这主要由于衣霉素抑制新合成的胰岛素受体的糖基化所致。

Tunicamycin is an inhibitor of the synthesis of N-linked oligosaccharide on glycoprotein. It was found that the growth of human hepatoca.rclnoma cell line SMMC-7721 was inhibited by tunicamycin; the inhibitory rate was proportional to the dose and the duration of tunicamycin treatment. After 18 hours of tunicamycin treat ment,a significant inhibition of the incorporation of ~3H-mannose and ~3H-glucosamine, but slight inhibition of the incorporation of ~3H-leucine into cell was observed. The inhibitory rate was dose-dependent. Treatment of 0.1μg/mL tunicamycin for 18 hours, the binding capacity of insulin to its receptor of the cell surface was decreased and the competitive binding curve of the treated cells and the control was nearly parallel to each other. This is mainly due to the inhibition of glycosylation of newly synthesized insulin receptor by tunicamycin. The mechanism that deglycosylation decreased the binding capacity of insulin receptor was discussed.