Ujházy P, Klobusická M, Babusíková O, Strausbauch P, Mihich E, Ehrke M J
Grace Cancer Drug Center, Roswell Park Cancer Institute, Buffalo, NY 14263.
Int J Cancer. 1994 Oct 1;59(1):83-93. doi: 10.1002/ijc.2910590117.
Cytochemical screening for a panel of enzymes revealed increased 5' nucleotidase (5'NT) expression in 3 of 3 P-glycoprotein 170 (Pgp170)-positive multidrug-resistant (MDR) variants of the murine EL4 T-lymphoma cell line (EL4/ADM, ER2 and ER13). Electron microscopic localization established the presence of the membrane-bound ecto-form of the enzyme. Nine other murine, human and Chinese hamster cell lines and their MDR variants were tested for ecto-5'NT. Of these, 4 MDR variants (human cell lines MCF7A6, MCF7A2, HeLaJ2C and the murine cell line L1210A) showed increased expression of ecto-5'NT, when compared with their parental cell lines. The findings with cells of human origin were confirmed by immunofluorescent localization with a specific monoclonal antibody (MAb) (27.2) against the human ecto-5'NT. All MDR cell lines with elevated ecto-5'NT expression were generated by doxorubicin treatment. These cells were more sensitive than their parental cell lines to AMP at concentrations of 1.5-3.0 mM, confirming that the expressed ecto-5'NT was biologically active. The parental and MDR cells did not differ, in general, in their sensitivity to adenosine. An inhibitor of ecto-5'NT, alpha,beta-methyleneadenosine 5'-diphosphate, completely reversed the resistance of the EL4/ADM cell line to doxorubicin. The possibility exists of a functional relationship between the ecto-5'NT molecule and the members of the ATP-binding cassette transporter superfamily, important components of MDR, in some cell types.
对一组酶进行细胞化学筛选发现，在鼠源EL4 T淋巴瘤细胞系（EL4/ADM、ER2和ER13）的3个P糖蛋白170（Pgp170）阳性多药耐药（MDR）变体中，5'核苷酸酶（5'NT）表达增加。电子显微镜定位确定了该酶膜结合胞外形式的存在。对另外9种鼠源、人源和中国仓鼠细胞系及其MDR变体进行了胞外5'NT检测。其中，4种MDR变体（人源细胞系MCF7A6、MCF7A2、HeLaJ2C和鼠源细胞系L1210A）与其亲本细胞系相比，胞外5'NT表达增加。用人源胞外5'NT特异性单克隆抗体（MAb）（27.2）进行免疫荧光定位，证实了人源细胞的研究结果。所有胞外5'NT表达升高的MDR细胞系均由阿霉素处理产生。这些细胞在1.5 - 3.0 mM浓度下对AMP比其亲本细胞系更敏感，证实所表达的胞外5'NT具有生物活性。亲本细胞和MDR细胞对腺苷的敏感性总体上没有差异。胞外5'NT抑制剂α,β-亚甲基腺苷5'-二磷酸完全逆转了EL4/ADM细胞系对阿霉素的耐药性。在某些细胞类型中，胞外5'NT分子与ATP结合盒转运蛋白超家族成员（MDR的重要组成部分）之间可能存在功能关系。
