Department of General Thoracic Surgery, Inselspital, Bern University Hospital, Murtenstrasse 28, 3008 Bern, Switzerland.
Oncology-Thoracic Malignancies, Department of BioMedical Research, University of Bern, 3010 Bern, Switzerland.
Int J Mol Sci. 2022 Oct 8;23(19):11949. doi: 10.3390/ijms231911949.
Malignant pleural mesothelioma (MPM) is a rare but aggressive thoracic malignancy with limited treatment options. One of the standard treatments for MPM is chemotherapy, which consists of concurrent treatment with pemetrexed and cisplatin. Pemetrexed limits tumor growth by inhibiting critical metabolic enzymes involved in nucleotide synthesis. Cisplatin causes direct DNA damage, such as intra-strand and inter-strand cross-links, which are repaired by the nucleotide excision repair pathway, which depends on relatively high nucleotide levels. We hypothesized that prolonged pretreatment with pemetrexed might deplete nucleotide pools, thereby sensitizing cancer cells to subsequent cisplatin treatment. The MPM cell lines ACC-MESO-1 and NCI-H28 were treated for 72 h with pemetrexed. Three treatment schedules were evaluated by initiating 24 h of cisplatin treatment at 0 h (concomitant), 24 h, and 48 h relative to pemetrexed treatment, resulting in either concomitant administration or pemetrexed pretreatment for 24 h or 48 h, respectively. Multicolor flow cytometry was performed to detect γH2AX (phosphorylation of histone H2AX), a surrogate marker for the activation of the DNA damage response pathway. DAPI staining of DNA was used to analyze cell cycle distribution. Forward and side scatter intensity was used to distinguish subpopulations based on cellular size and granularity, respectively. Our study revealed that prolonged pemetrexed pretreatment for 48 h prior to cisplatin significantly reduced long-term cell growth. Specifically, pretreatment for 48 h with pemetrexed induced a cell cycle arrest, mainly in the G2/M phase, accumulation of persistent DNA damage, and induction of a senescence phenotype. The present study demonstrates that optimizing the treatment schedule by pretreatment with pemetrexed increases the efficacy of the pemetrexed-cisplatin combination therapy in MPM. We show that the observed benefits are associated with the persistence of treatment-induced DNA damage. Our study suggests that an adjustment of the treatment schedule could improve the efficacy of the standard chemotherapy regimen for MPM and might improve patient outcomes.
恶性胸膜间皮瘤（MPM）是一种罕见但侵袭性的胸部恶性肿瘤，治疗选择有限。MPM 的标准治疗之一是化疗，包括培美曲塞和顺铂联合治疗。培美曲塞通过抑制核苷酸合成中涉及的关键代谢酶来限制肿瘤生长。顺铂导致直接的 DNA 损伤，如链内和链间交联，这些交联通过核苷酸切除修复途径修复，该途径依赖于相对较高的核苷酸水平。我们假设，培美曲塞的预先延长治疗可能会耗尽核苷酸池，从而使癌细胞对随后的顺铂治疗敏感。MPM 细胞系 ACC-MESO-1 和 NCI-H28 用培美曲塞处理 72 小时。通过在培美曲塞处理后 0 小时（同时）、24 小时和 48 小时开始顺铂处理，评估了三种治疗方案，分别导致同时给药或培美曲塞预处理 24 小时或 48 小时。通过多色流式细胞术检测 γH2AX（组蛋白 H2AX 的磷酸化），这是 DNA 损伤反应途径激活的替代标志物。用 DAPI 染色 DNA 分析细胞周期分布。前向和侧向散射强度分别用于根据细胞大小和粒度区分亚群。我们的研究表明，在顺铂之前，培美曲塞预先延长治疗 48 小时可显著减少长期细胞生长。具体而言，培美曲塞预处理 48 小时可诱导细胞周期停滞，主要在 G2/M 期，积累持久的 DNA 损伤，并诱导衰老表型。本研究表明，通过培美曲塞预处理优化治疗方案可提高培美曲塞-顺铂联合治疗 MPM 的疗效。我们表明，观察到的益处与治疗诱导的 DNA 损伤的持续存在有关。我们的研究表明，调整治疗方案可以提高 MPM 标准化疗方案的疗效，并可能改善患者的预后。
