Zhang J, Zhang J, Yuan Y
Oncology Center, Zhujiang Hospital, First Military Medical University, Guangzhou 510282, China.
Zhonghua Zhong Liu Za Zhi. 2001 Mar;23(2):111-4.
To study the relationship between MDR and expression of N-glycosphingolipids (H-GSLs) in tumor cells.
Ribozyme with specific catalytic activity, capable of cleaving mdr1 mRNA, was transfected into KBv200 cells. RNA dot blot was used to detect the expression of ribozyme in the transfected cells. Northern blot and immunocytochemistry were employed to examine the expression of mdr1 mRNA and P-glycoprotein. Cellular N-GSLs was isolated and purified with a modified Hakamori's method and analysed by high performance TLC. The effect of DL-PPMP, a glycolipids synthase inhibitor, on the reversion of MDR was assayed by MTT method.
The ribozyme stably expressed in KBv200/5mR3 cells decreased the level of mdr1 mRNA expression by 81.9% and inhibited the formation of P-glycoprotein. The levels of monohexosylceramide (CMH) and dihexosylceramide (CDH) in KBv200 cells were increased as compared to those in KB cells. When MDR was reversed by the ribozyme, the KBv200/5mR3 showed a sharply decreased level of CMH. PPMP could reverse MDR by inhibiting synthesis of CMH.
CMH is a kind of MDR-related glycolipid. Inhibition of its expression in tumor cells may be a new approach to reverse MDR.
研究肿瘤细胞中多药耐药（MDR）与N-糖鞘脂（H-GSLs）表达之间的关系。
将具有特异性催化活性、能够切割mdr1 mRNA的核酶转染至KBv200细胞中。采用RNA斑点杂交检测转染细胞中核酶的表达。运用Northern印迹法和免疫细胞化学法检测mdr1 mRNA和P-糖蛋白的表达。采用改良的Hakamori法分离纯化细胞N-GSLs，并用高效薄层层析法进行分析。通过MTT法检测糖脂合成抑制剂DL-PPMP对MDR逆转的作用。
在KBv200/5mR3细胞中稳定表达的核酶使mdr1 mRNA表达水平降低了81.9%，并抑制了P-糖蛋白的形成。与KB细胞相比，KBv200细胞中单己糖神经酰胺（CMH）和二己糖神经酰胺（CDH）的水平升高。当核酶逆转MDR时，KBv200/5mR3细胞中CMH水平急剧下降。PPMP可通过抑制CMH的合成来逆转MDR。
CMH是一种与MDR相关的糖脂。抑制其在肿瘤细胞中的表达可能是逆转MDR的一种新方法。
