Laboratory of Biomolecular Systems Signaling, Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil.
Cell Death Dis. 2023 Apr 21;14(4):283. doi: 10.1038/s41419-023-05812-1.
Glioblastoma (GBM), the most common aggressive brain tumor, is characterized by rapid cellular infiltration and is routinely treated with ionizing radiation (IR), but therapeutic resistance inevitably recurs. The actin cytoskeleton of glioblastoma cells provides their high invasiveness, but it remains unclear whether Rho GTPases modulate DNA damage repair and therapeutic sensitivity. Here, we irradiated glioblastoma cells with different p53 status and explored the effects of Rho pathway inhibition to elucidate how actin cytoskeleton disruption affects the DNA damage response and repair pathways. p53-wild-type and p53-mutant cells were subjected to Rho GTPase pathway modulation by treatment with C3 toxin; knockdown of mDia-1, PFN1 and MYPT1; or treatment with F-actin polymerization inhibitors. Rho inhibition increased the sensitivity of glioma cells to IR by increasing the number of DNA double-strand breaks and delaying DNA repair by nonhomologous end-joining in p53-wild-type cells. p53 knockdown reversed this phenotype by reducing p21 expression and Rho signaling activity, whereas reactivation of p53 in p53-mutant cells by treatment with PRIMA-1 reversed these effects. The interdependence between p53 and Rho is based on nuclear p53 translocation facilitated by G-actin and enhanced by IR. Isolated IR-resistant p53-wild-type cells showed an altered morphology and increased stress fiber formation: inhibition of Rho or actin polymerization decreased cell viability in a p53-dependent manner and reversed the resistance phenotype. p53 silencing reversed the Rho inhibition-induced sensitization of IR-resistant cells. Rho inhibition also impaired the repair of IR-damaged DNA in 3D spheroid models. Rho GTPase activity and actin cytoskeleton dynamics are sensitive targets for the reversal of acquired resistance in GBM tumors with wild-type p53.
胶质母细胞瘤（GBM）是最常见的侵袭性脑肿瘤，其特征是细胞快速浸润，常规采用电离辐射（IR）治疗，但治疗抵抗不可避免地会复发。胶质母细胞瘤细胞的肌动蛋白细胞骨架赋予其高侵袭性，但尚不清楚 Rho GTPases 是否调节 DNA 损伤修复和治疗敏感性。在这里，我们用不同 p53 状态的胶质母细胞瘤细胞进行照射，并探讨 Rho 通路抑制的影响，以阐明肌动蛋白细胞骨架破坏如何影响 DNA 损伤反应和修复途径。用 C3 毒素处理 p53 野生型和 p53 突变型细胞，以调节 Rho GTPase 通路；敲低 mDia-1、PFN1 和 MYPT1；或用 F-肌动蛋白聚合抑制剂处理。Rho 抑制通过增加 DNA 双链断裂的数量并延迟非同源末端连接修复，增加了 p53 野生型细胞对 IR 的敏感性。p53 敲低通过降低 p21 表达和 Rho 信号活性逆转了这种表型，而用 PRIMA-1 处理 p53 突变型细胞使 p53 重新激活则逆转了这些作用。p53 和 Rho 之间的相互依赖关系基于 G-肌动蛋白促进的核内 p53 易位，并受 IR 增强。分离出的 IR 耐药 p53 野生型细胞表现出形态改变和应力纤维形成增加：抑制 Rho 或肌动蛋白聚合以 p53 依赖性方式降低细胞活力，并逆转耐药表型。p53 沉默逆转了 Rho 抑制诱导的 IR 耐药细胞的敏化作用。Rho 抑制也损害了 3D 球体模型中 IR 损伤 DNA 的修复。Rho GTPase 活性和肌动蛋白细胞骨架动力学是逆转具有野生型 p53 的 GBM 肿瘤获得性耐药的敏感靶点。
