Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France.
Fibermetrix, 7 Allée De l'Europe, Entsheim, France.
Curr Eye Res. 2021 Apr;46(4):546-557. doi: 10.1080/02713683.2020.1808998. Epub 2020 Aug 30.
PURPOSE/AIM OF THE STUDY: Retinoblastoma (Rb) is a rare form of pediatric cancer that develops from retina cells. Bilateral and some unilateral forms of Rb are associated with heterozygous germline mutations of the (retinoblastoma 1) gene. mutations are also associated with a significant risk of secondary malignancy like head and neck tumors. Hence, to date, even if Rb patients are less subjected to radiotherapy to treat their primary ocular tumors, their healthy tissues may be exposed to significant doses of ionizing radiation during the treatment against their secondary malignancies with a significant risk of adverse tissue reactions (radiosensitivity) and/or radiation-induced cancer (radiosusceptibility). However, the biological role of the Rb protein in response to radiation remains misunderstood. Since the ataxia telangiectasia mutated (ATM) protein is a key protein of radiation response and since untransformed skin fibroblasts are a current model to quantify cellular radiosensitivity, we investigated here for the first time the functionality of the ATM-dependent signaling and repair pathway of the radiation-induced DNA double-strand breaks (DSB) in irradiated skin fibroblasts derived from Rb patients.
The major biomarkers of the DSB repair and signaling, namely clonogenic cell survival, micronuclei, nuclear foci of the phosphorylated forms of the X variant of the H2A histone (γH2AX), the phosphorylated forms of the ATM protein (pATM) and the meiotic recombination 11 nuclease (MRE11) were assessed in untransformed skin fibroblasts derived from three Rb patients.
Skin fibroblasts from Rb patients showed significant cellular radiosensitivity, incomplete DSB recognition, delay in the ATM nucleo-shuttling and exacerbated MRE11 nuclease activity. Treatment with statin and bisphosphonates led to significant complementation of these impairments.
Our findings strongly suggest the involvement of the ATM kinase in the radiosensitivity/radiosusceptibility phenotype observed in Rb cases.
目的/研究目的：视网膜母细胞瘤（Rb）是一种罕见的儿科癌症，起源于视网膜细胞。双侧和一些单侧 Rb 与（视网膜母细胞瘤 1）基因的杂合胚系突变有关。这些突变也与头颈部肿瘤等继发性恶性肿瘤的发生风险显著相关。因此，迄今为止，即使 Rb 患者在治疗其原发性眼部肿瘤时较少接受放射治疗，他们的健康组织在治疗继发性恶性肿瘤时也可能暴露于大量电离辐射下，存在组织不良反应（辐射敏感性）和/或辐射诱导癌症（辐射易感性）的显著风险。然而，Rb 蛋白在辐射反应中的生物学作用仍未被充分理解。由于共济失调毛细血管扩张突变（ATM）蛋白是辐射反应的关键蛋白，并且未转化的皮肤成纤维细胞是量化细胞辐射敏感性的当前模型，因此我们首次研究了源自 Rb 患者的辐射诱导 DNA 双链断裂（DSB）的 ATM 依赖性信号转导和修复途径的功能。
我们评估了源自三位 Rb 患者的未转化皮肤成纤维细胞中的 DSB 修复和信号的主要生物标志物，即克隆形成细胞存活、微核、X 变体组蛋白 H2A 的磷酸化形式（γH2AX）的核焦点、ATM 蛋白的磷酸化形式（pATM）和减数分裂重组 11 核酸酶（MRE11）。
Rb 患者的皮肤成纤维细胞表现出显著的细胞辐射敏感性、不完全的 DSB 识别、ATM 核穿梭延迟以及加剧的 MRE11 核酸酶活性。他汀类药物和双膦酸盐的治疗导致这些缺陷得到显著补偿。
我们的研究结果强烈表明 ATM 激酶参与了 Rb 病例中观察到的辐射敏感性/辐射易感性表型。
