Sharma Shivani, Santiskulvong Chintda, Rao Jianyu, Gimzewski James K, Dorigo Oliver
Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA.
Integr Biol (Camb). 2014 Jun;6(6):611-7. doi: 10.1039/c3ib40246k.
Changes in cell stiffness (Young's modulus, E), as measured via Atomic Force Microscopy (AFM), is a newly recognized characteristic of cancer cells and may play a role in platinum drug resistance of ovarian cancers. We previously showed that, compared to their syngeneic cisplatin-sensitive counterpart, cisplatin-resistant ovarian cancer cells are stiffer, and this cell stiffness was dependent on actin polymerization and presence of stress fibers. Here, we measured the correlation between Young's modulus (via AFM measurements on live, non-apoptotic cells in physiological buffer) and cisplatin-sensitivity (IC50 as determined via the XTT cell viability assay) in a panel of nine ovarian cancer cell lines representing a range of cisplatin sensitivities. We found that cisplatin-sensitive cells had a lower Young's modulus, compared to cisplatin-resistant cells and resistant cells had a cytoskeleton composed of long actin stress fibers. As Rho GTPase mediates stress fiber formation, we examined the role of Rho GTPase in cell stiffness and platinum resistance. Rho inhibition decreased cell stiffness in cisplatin-resistant CP70 cells and increased their cisplatin sensitivity while Rho activation increased cell stiffness in cisplatin-sensitive A2780 cells and decreased their cisplatin sensitivity. Based on changes in cell stiffness, IC50 and cellular actin stress fiber organization in CP70 and A2780 cells, our findings reveal a direct role of Rho mediated actin remodeling mechanism in cisplatin resistance of ovarian cancer cells. These findings suggest the potential applicability of cell mechanical phenotyping as a model for determining sensitivity of ovarian cancer cells that could have major implications in ovarian cancer diagnosis and personalized medicine.
通过原子力显微镜（AFM）测量的细胞硬度（杨氏模量，E）变化是癌细胞新发现的一个特征，可能在卵巢癌顺铂耐药中发挥作用。我们之前表明，与同基因的顺铂敏感对应细胞相比，顺铂耐药的卵巢癌细胞更硬，并且这种细胞硬度依赖于肌动蛋白聚合和应力纤维的存在。在这里，我们在一组代表不同顺铂敏感性的9种卵巢癌细胞系中，测量了杨氏模量（通过在生理缓冲液中对活的、未凋亡细胞进行AFM测量）与顺铂敏感性（通过XTT细胞活力测定法确定的IC50）之间的相关性。我们发现，与顺铂耐药细胞相比，顺铂敏感细胞的杨氏模量更低，且耐药细胞具有由长肌动蛋白应力纤维组成的细胞骨架。由于Rho GTP酶介导应力纤维形成，我们研究了Rho GTP酶在细胞硬度和铂耐药中的作用。Rho抑制降低了顺铂耐药的CP70细胞的硬度，并增加了它们对顺铂的敏感性，而Rho激活增加了顺铂敏感的A2780细胞的硬度，并降低了它们对顺铂的敏感性。基于CP70和A2780细胞中细胞硬度、IC50和细胞肌动蛋白应力纤维组织的变化，我们的研究结果揭示了Rho介导的肌动蛋白重塑机制在卵巢癌细胞顺铂耐药中的直接作用。这些发现表明细胞力学表型分析作为一种确定卵巢癌细胞敏感性的模型具有潜在的适用性，这可能对卵巢癌诊断和个性化医疗有重大影响。
