Department of Medical Sciences, Division of Clinical Pharmacology, Uppsala University, Uppsala, Sweden.
BMC Cancer. 2013 Aug 6;13:374. doi: 10.1186/1471-2407-13-374.
Drug resistance is a common cause of treatment failure in cancer patients and encompasses a multitude of different mechanisms. The aim of the present study was to identify drugs effective on multidrug resistant cells.
The RPMI 8226 myeloma cell line and its multidrug resistant subline 8226/Dox40 was screened for cytotoxicity in response to 3,000 chemically diverse compounds using a fluorometric cytotoxicity assay (FMCA). Follow-up profiling was subsequently performed using various cellular and biochemical assays.
One compound, designated VLX40, demonstrated a higher activity against 8226/Dox40 cells compared to its parental counterpart. VLX40 induced delayed cell death with apoptotic features. Mechanistic exploration was performed using gene expression analysis of drug exposed tumor cells to generate a drug-specific signature. Strong connections to tubulin inhibitors and microtubule cytoskeleton were retrieved. The mechanistic hypothesis of VLX40 acting as a tubulin inhibitor was confirmed by direct measurements of interaction with tubulin polymerization using a biochemical assay and supported by demonstration of G2/M cell cycle arrest. When tested against a broad panel of primary cultures of patient tumor cells (PCPTC) representing different forms of leukemia and solid tumors, VLX40 displayed high activity against both myeloid and lymphoid leukemias in contrast to the reference compound vincristine to which myeloid blast cells are often insensitive. Significant in vivo activity was confirmed in myeloid U-937 cells implanted subcutaneously in mice using the hollow fiber model.
The results indicate that VLX40 may be a useful prototype for development of novel tubulin active agents that are insensitive to common mechanisms of cancer drug resistance.
耐药性是癌症患者治疗失败的常见原因，涉及多种不同的机制。本研究旨在确定对多药耐药细胞有效的药物。
使用荧光细胞毒性测定法（FMCA）筛选 RPMI 8226 骨髓瘤细胞系及其多药耐药亚系 8226/Dox40 对 3000 种不同化合物的细胞毒性。随后使用各种细胞和生化测定法进行后续分析。
一种名为 VLX40 的化合物对 8226/Dox40 细胞的活性明显高于其亲本细胞。VLX40 诱导具有凋亡特征的迟发性细胞死亡。通过对暴露于药物的肿瘤细胞进行基因表达分析来进行机制探索，以生成药物特异性特征。发现与微管蛋白抑制剂和微管细胞骨架有很强的联系。VLX40 作为微管蛋白抑制剂的作用机制通过使用生化测定法直接测量与微管蛋白聚合的相互作用得到证实，并通过证明 G2/M 细胞周期阻滞得到支持。当对代表不同白血病和实体瘤形式的患者肿瘤细胞（PCPTC）的广泛原发性培养物进行测试时，VLX40 对髓样和淋巴样白血病均表现出高活性，与参考化合物长春新碱形成对比，长春新碱通常对髓样原始细胞不敏感。在使用中空纤维模型植入皮下的髓样 U-937 细胞中进行的体内研究中证实了显著的活性。
结果表明，VLX40 可能是开发对常见癌症耐药机制不敏感的新型微管蛋白活性药物的有用原型。
