Resistance to radio and chemotherapy in Glioblastoma (GBM) is correlated with its malignancy, invasiveness, and aggressiveness. The Rho GTPase pathway plays important roles in these processes, but its involvement in the GBM response to genotoxic treatments remains unsolved. Inhibition of this signaling pathway has emerged as a promising approach for the treatment of CNS injuries and diseases, proving to be a strong candidate for therapeutic approaches. To this end, Rho-associated kinases (ROCK), classic downstream effectors of small Rho GTPases, were targeted for pharmacological inhibition using Y-27632 in GBM cells, expressing the wild-type or mutated p53 gene, and exposed to genotoxic stress by gamma ionizing radiation (IR) or cisplatin (PT). The use of the ROCK inhibitor (ROCKi) had opposite effects in these cells: in cells expressing wild-type p53, ROCKi reduced survival and DNA repair capacity (reduction of γH2AX foci and accumulation of strand breaks) after stress promoted by IR or PT; in cells expressing the mutant p53 protein, both treatments promoted longer survival and more efficient DNA repair, responses further enhanced by ROCKi. The target DNA repair mechanisms of ROCK inhibition were, respectively, an attenuation of NHEJ and NER pathways in wild-type p53 cells, and a stimulation of HR and NER pathways in mutant p53 cells. These effects were accompanied by the formation of reactive oxygen species (ROS) induced by genotoxic stress only in mutant p53 cells but potentiated by ROCKi and reversed by p53 knockdown. N-acetyl-L-cysteine (NAC) treatment or Rac1 knockdown completely eliminated ROCKi's p53-dependent actions, since ROCK inhibition specifically elevated Rac-GTP levels only in mutant p53 cells. Combining IR or PT and ROCKi treatments broadens our understanding of the sensitivity and resistance of, respectively, GBM expressing wild-type or mutant p53 to genotoxic agents. Our proposal may be a determining factor in improving the efficiency and assertiveness of CNS antitumor therapies based on ROCK inhibitors.

Significance

The use of ROCK inhibitors in association with radio or chemotherapy modulates GBM resistance and sensitivity depending on the p53 activity, suggesting the potential value of this protein as therapeutic target for tumor pre-sensitization strategies.

中文翻译：

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ROCK 抑制通过 Rac1 驱动的 ROS 产生降低突变 p53 胶质母细胞瘤对基因毒性应激的敏感性

胶质母细胞瘤（GBM）对放疗和化疗的耐药性与其恶性程度、侵袭性和侵袭性相关。Rho GTPase通路在这些过程中发挥着重要作用，但其在 GBM 对基因毒性治疗的反应中的参与仍未得到解决。抑制该信号通路已成为治疗中枢神经系统损伤和疾病的一种有前景的方法，并被证明是治疗方法的有力候选者。为此，Rho相关激酶（ROCK）是小Rho GTPases的经典下游效应子，在GBM细胞中使用Y-27632进行药理抑制，表达野生型或突变的p53基因，并暴露于gamma的基因毒性应激电离辐射 (IR) 或顺铂(PT)。使用 ROCK 抑制剂 (ROCKi) 在这些细胞中产生相反的效果：在表达野生型 p53 的细胞中，ROCKi 在 IR 或 PT 促进的应激后降低了存活率和 DNA 修复能力（γH2AX 焦点的减少和链断裂的积累）；在表达突变 p53 蛋白的细胞中，两种治疗都促进了更长的存活时间和更有效的 DNA 修复，ROCKi 进一步增强了反应。ROCK抑制的靶DNA修复机制分别是野生型p53细胞中NHEJ和NER途径的减弱，以及突变型p53细胞中HR和NER途径的刺激。这些效应伴随着仅在突变 p53 细胞中由基因毒性应激诱导的活性氧 (ROS) 的形成，但通过 ROCKi 增强，并通过 p53 敲低逆转。N-乙酰基-L-半胱氨酸 (NAC) 处理或 Rac1 敲除完全消除了 ROCKi 的 p53 依赖性作用，因为 ROCK 抑制仅在突变 p53 细胞中特异性升高 Rac-GTP 水平。将 IR 或 PT 与 ROCKi 治疗相结合，拓宽了我们对表达野生型或突变型 p53 的 GBM 对基因毒剂的敏感性和耐药性的理解。我们的建议可能是提高基于 ROCK 抑制剂的 CNS 抗肿瘤疗法的效率和自信的决定性因素。

意义

ROCK 抑制剂与放疗或化疗结合使用可根据 p53 活性调节 GBM 耐药性和敏感性，表明该蛋白作为肿瘤预致敏策略的治疗靶点的潜在价值。