The Small Molecule Inhibitor QLT0267 Radiosensitizes Squamous Cell Carcinoma Cells of the Head and Neck
The Small Molecule Inhibitor QLT0267 Radiosensitizes Squamous Cell Carcinoma Cells of the Head and Neck
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DOI：
10.1371/journal.pone.0006434
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发表时间：
2009-07-30
期刊：
影响因子：
3.7
通讯作者：
Cordes, Nils
中科院分区：
文献类型：
--
作者：
Eke, Iris;Leonhardt, Franziska;Cordes, Nils
背景资料：癌细胞对放疗和化疗的抵抗力不断增加，阻碍了患者生存率的提高，需要新的靶向方法。整合素连接激酶（ILK）已被假定为有效的药物治疗癌症的目标。基于我们先前的研究结果清楚地表明ILK在暴露于电离辐射的细胞中转导抗存活信号，本研究评估了小分子抑制剂QLT 0267（报告为推定的ILK抑制剂）对人头颈部鳞状细胞癌细胞（hHNSCC）的细胞辐射存活反应的影响。使用亲本FaDu细胞和用组成型活性ILK突变体（FaDu-IH）或空载体稳定转染的FaDu细胞、UTSCC 45细胞、ILKfloxed/floxed（fl/fl）和ILK-/-小鼠成纤维细胞。细胞在富含层粘连蛋白的细胞外基质上二维（2D）或三维（3D）生长。用QLT 0267单独或与辐射（X射线，0-6戈伊单剂量）组合处理细胞。通过小干扰RNA转染实现ILK敲低。测定ILK激酶活性、克隆形成存活率、残留DNA双链断裂数（rDSB; cH 2AX/53 BP 1病灶测定）、细胞周期分布、蛋白质表达和磷酸化（例如Akt、p44/42丝裂原活化蛋白激酶（MAPK））。关于ILK激酶活性和Akt和p44/42 MAPK的磷酸化的数据揭示了QLT 0267对ILK没有特异性的宽抑制谱。QLT 0267以时间和浓度依赖性方式显著降低FaDu和UTSCC 45细胞的基底细胞存活并增强放射敏感性。QLT 0267对放射性rDSB和G2细胞周期期细胞蓄积产生差异性细胞培养模型依赖性效应。相对于相应的对照，FaDu-IH和ILKfl/fl成纤维细胞显示出增强的放射敏感性，其不能被QLT 0267拮抗。ILK的敲除揭示了没有变化，在克隆生存的测试细胞系相比，controls.Conclusions/Significance：我们的数据清楚地表明，小分子抑制剂QLT 0267在hHNSCC细胞具有强大的细胞毒性和放射增敏能力。然而，QLT 0267对ILK无特异性。有必要进行进一步的体外和体内研究，以阐明QLT 0267作为临床靶向治疗药物的潜力。
Background: The constant increase of cancer cell resistance to radio-and chemotherapy hampers improvement of patient survival and requires novel targeting approaches. Integrin-Linked Kinase ( ILK) has been postulated as potent druggable cancer target. On the basis of our previous findings clearly showing that ILK transduces antisurvival signals in cells exposed to ionizing radiation, this study evaluated the impact of the small molecule inhibitor QLT0267, reported as putative ILK inhibitor, on the cellular radiation survival response of human head and neck squamous cell carcinoma cells (hHNSCC).Methodology/Principal Findings: Parental FaDu cells and FaDu cells stably transfected with a constitutively active ILK mutant (FaDu-IH) or empty vectors, UTSCC45 cells, ILKfloxed/floxed(fl/fl) and ILK-/- mouse fibroblasts were used. Cells grew either two-dimensionally (2D) on or three-dimensionally (3D) in laminin-rich extracellular matrix. Cells were treated with QLT0267 alone or in combination with irradiation (X-rays, 0-6 Gy single dose). ILK knockdown was achieved by small interfering RNA transfection. ILK kinase activity, clonogenic survival, number of residual DNA double strand breaks (rDSB; cH2AX/53BP1 foci assay), cell cycle distribution, protein expression and phosphorylation (e.g. Akt, p44/42 mitogen-activated protein kinase ( MAPK)) were measured. Data on ILK kinase activity and phosphorylation of Akt and p44/42 MAPK revealed a broad inhibitory spectrum of QLT0267 without specificity for ILK. QLT0267 significantly reduced basal cell survival and enhanced the radiosensitivity of FaDu and UTSCC45 cells in a time- and concentration-dependent manner. QLT0267 exerted differential, cell culture model-dependent effects with regard to radiogenic rDSB and accumulation of cells in the G2 cell cycle phase. Relative to corresponding controls, FaDu-IH and ILKfl/fl fibroblasts showed enhanced radiosensitivity, which failed to be antagonized by QLT0267. A knockdown of ILK revealed no change in clonogenic survival of the tested cell lines as compared to controls.Conclusions/Significance: Our data clearly show that the small molecule inhibitor QLT0267 has potent cytotoxic and radiosensitizing capability in hHNSCC cells. However, QLT0267 is not specific for ILK. Further in vitro and in vivo studies are necessary to clarify the potential of QLT0267 as a targeted therapeutic in the clinic.