specific β-tubulin isotypes can functionally enhance or diminish epothilone b sensitivity in non-small cell lung cancer cells具体β-tubulin同形像可以功能增强或削弱epothilone b在非小细胞肺癌细胞的敏感性.pdf

Specific b-Tubulin Isotypes Can Functionally Enhance or Diminish Epothilone B Sensitivity in Non-Small Cell Lung Cancer Cells 1 1 1 2 1,3 Pei Pei Gan , Joshua A. McCarroll , Frances L. Byrne , James Garner , Maria Kavallaris * 1 Children’s Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales, Randwick, Australia, 2 School of Chemistry, University of New South Wales, Sydney, Australia, 3 Australian Centre for Nanomedicine, University of New South Wales, Sydney, Australia Abstract Epothilones are a new class of microtubule stabilizing agents with promising preclinical and clinical activity. Their cellular target is b-tubulin and factors influencing intrinsic sensitivity to epothilones are not well understood. In this study, the functional significance of specific b-tubulin isotypes in intrinsic sensitivity to epothilone B was investigated using siRNA gene knockdown against bII-, bIII- or bIVb-tubulins in two independent non-small cell lung cancer (NSCLC) cell lines, NCI- H460 and Calu-6. Drug-treated clonogenic assays showed that sensitivity to epothilone B was not altered following knockdown of bII-tubulin in both NSCLC cell lines. In contrast, knockdown of bIII-tubulin significantly increased sensitivity to epothilone B. Interestingly, bIVb-tubulin knockdowns were significantly less sensitive to epothilone B, compared to mock- and control siRNA cells. Cell cycle analysis of bIII-tubulin knockdown cells showed a higher percentage of cell death with epothilone B concentrations as low as 0.5 nM. In contrast, bIVb-tubulin knockdown cells displayed a decrease in epothilone B-induced G2-M cell cycle accumulation compared to c