Haber M, Burkhart C A, Regl D L, Madafiglio J, Norris M D, Horwitz S B
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
J Biol Chem. 1995 Dec 29;270(52):31269-75. doi: 10.1074/jbc.270.52.31269.
A series of taxol- and taxotere-resistant J774.2 cell lines has been characterized with respect to altered expression of beta-tubulin, the cellular target for these drugs. Vertebrates have six classes of beta-tubulin isotypes, each displaying a distinct pattern of expression. Although the functional significance of multiple beta-tubulins has not been fully defined, there is evidence that the individual isotypes contribute to differences in microtubule dynamics and drug binding. To determine if alterations in the expression of beta-tubulin isotypes play a role in taxol resistance, a PCR-based methodology was developed that permits highly specific amplification of each of the six known murine beta-tubulin isotypes. Two isotypes, M beta 5 and M beta 3, were expressed abundantly in the drug-sensitive parental J774.2 cells. Although expressed at an extremely low level in the parental cells, expression of the M beta 2 isotype was increased 21-fold (< 0.005) in the cell line most resistant to taxol. These findings suggest that a cell can alter its relative tubulin isotype composition in response to an external stress and specifically imply that altered expression of M beta 2, the class II beta-tubulin isotype, may contribute to the development of high resistance to taxol.
一系列对紫杉醇和多西他赛耐药的J774.2细胞系已针对β-微管蛋白（这些药物的细胞靶点）表达的改变进行了表征。脊椎动物有六类β-微管蛋白亚型，每类都呈现出独特的表达模式。尽管多种β-微管蛋白的功能意义尚未完全明确，但有证据表明各个亚型对微管动力学和药物结合的差异有影响。为了确定β-微管蛋白亚型表达的改变是否在紫杉醇耐药中起作用，开发了一种基于PCR的方法，该方法可对六种已知的小鼠β-微管蛋白亚型中的每一种进行高度特异性扩增。两种亚型，Mβ5和Mβ3，在药物敏感的亲本J774.2细胞中大量表达。尽管Mβ2亚型在亲本细胞中表达水平极低，但在对紫杉醇最耐药的细胞系中其表达增加了21倍（<0.005）。这些发现表明细胞可以响应外部应激改变其相对微管蛋白亚型组成，特别意味着II类β-微管蛋白亚型Mβ2表达的改变可能有助于对紫杉醇产生高度耐药性。
