Background: Ataxia telangiectasia mutated (ATM), DNA damage response, cisplatin, neem, nimbolide, oral squamous cell carcinoma, patient-derived xenograft. Objective: The present study was designed to investigate whether nimbolide, an anticancer neem limonoid, targets key components of the DDR signalling pathway in cellular and animal models of oral squamous cell carcinoma (OSCC). Methods: OSCC cells (SCC-4 and SCC-9), 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinoma model, chemoresistant OSCC patient-derived xenograft (PDX) model established in athymic nude mice, and tissue sections from patients with oral premalignant/malignant disease were used for the study. Key molecules that orchestrate the DDR, including the MRN complex, ATM, DNA-PKcs, H2AX, and p53, were analysed by qRTPCR, immunoblotting, immunofluorescence, and immunohistochemistry. Cell proliferation and apoptosis indices were evaluated. Results: Nimbolide significantly reduced 8-oxodG levels, expression of MRN, ATMS1891, and g- H2AX, with an increase in p-p53S15 in OSCC cells as well as in the HBP model. Nimbolide potentiated the effect of KU-55933 in ATM inhibition. In the PDX model, nimbolide suppressed tumor formation, stimulated DDR and apoptosis, inhibited cell proliferation, and enhanced sensitivity to cisplatin. Analysis of p-ATM expression revealed a significant increase during the sequential progression of hamster and human OSCC. Conclusions: This study provides compelling evidence that nimbolide functions as a DDR inhibitor in cellular and hamster OSCC models and as a DDR activator in the PDX model primarily by targeting ATM. Small molecules like nimbolide that modulate DDR are of immense benefit in cancer therapy. The study has also unveiled p-ATM as a promising biomarker of tumour progression in human OSCCs.

中文翻译：

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印楝柠檬苦素内酯调节口腔鳞状细胞癌细胞和动物模型中 DNA 损伤反应信号的关键成分

背景：共济失调毛细血管扩张突变 (ATM)、DNA 损伤反应、顺铂、印楝、印楝内酯、口腔鳞状细胞癌、患者来源的异种移植物。目的：本研究旨在探讨印楝内酯（一种抗癌印楝柠檬苦素）是否针对口腔鳞状细胞癌（OSCC）细胞和动物模型中 DDR 信号通路的关键成分。方法：OSCC细胞（SCC-4和SCC-9）、7,12-二甲基苯并[a]蒽（DMBA）诱导的仓鼠颊囊（HBP）癌模型、在无胸腺中建立的化疗耐药OSCC患者来源的异种移植（PDX）模型该研究使用裸鼠和口腔癌前/恶性疾病患者的组织切片。通过 qRTPCR、免疫印迹、免疫荧光和免疫组织化学分析了协调 DDR 的关键分子，包括 MRN 复合物、ATM、DNA-PKcs、H2AX 和 p53。评估细胞增殖和凋亡指数。结果：印苦内酯显着降低 OSCC 细胞和 HBP 模型中的 8-oxodG 水平以及 MRN、ATMS1891 和 g-H2AX 的表达，同时增加 p-p53S15。 Nimbolide 增强了 KU-55933 在 ATM 抑制中的作用。在PDX模型中，印楝内酯抑制肿瘤形成，刺激DDR和细胞凋亡，抑制细胞增殖，并增强对顺铂的敏感性。对 p-ATM 表达的分析表明，在仓鼠和人类 OSCC 的连续进展过程中，p-ATM 表达显着增加。结论：这项研究提供了令人信服的证据，表明印楝内酯在细胞和仓鼠 OSCC 模型中充当 DDR 抑制剂，并主要通过靶向 ATM 在 PDX 模型中充当 DDR 激活剂。像印苦内酯这样调节 DDR 的小分子在癌症治疗中具有巨大的益处。该研究还揭示了 p-ATM 作为人类 OSCC 肿瘤进展的有前途的生物标志物。