Sato Yuzo, Tomita Masaru, Soga Tomoyoshi, Ochiai Atsushi, Makinoshima Hideki
Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Japan.
Shonai Regional Industry Promotion Center, Tsuruoka, Japan.
Front Pharmacol. 2021 Sep 27;12:718675. doi: 10.3389/fphar.2021.718675. eCollection 2021.
Malignant pleural mesothelioma (MPM) is an invasive malignancy that develops in the pleural cavity, and antifolates are used as chemotherapeutics for treating. The majority of antifolates, including pemetrexed (PMX), inhibit enzymes involved in purine and pyrimidine synthesis. MPM patients frequently develop drug resistance in clinical practice, however the associated drug-resistance mechanism is not well understood. This study was aimed to elucidate the mechanism underlying resistance to PMX in MPM cell lines. We found that among the differentially expressed genes associated with drug resistance (determined by RNA sequencing), TYMS expression was higher in the established resistant cell lines than in the parental cell lines. Knocking down expression significantly reduced drug resistance in the resistant cell lines. Conversely, overexpression significantly increased drug resistance in the parental cells. Metabolomics analysis revealed that the levels of dTMP were higher in the resistant cell lines than in the parental cell lines; however, resistant cells showed no changes in dTTP levels after PMX treatment. We found that the nucleic acid-biosynthetic pathway is important for predicting the efficacy of PMX in MPM cells. The results of chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR) assays suggested that H3K27 acetylation in the 5'-UTR of may promote its expression in drug-resistant cells. Our findings indicate that the intracellular levels of dTMP are potential biomarkers for the effective treatment of patients with MPM and suggest the importance of regulatory mechanisms of TYMS expression in the disease.
恶性胸膜间皮瘤（MPM）是一种发生于胸膜腔的侵袭性恶性肿瘤，抗叶酸药物被用作治疗的化疗药物。大多数抗叶酸药物，包括培美曲塞（PMX），抑制参与嘌呤和嘧啶合成的酶。然而，在临床实践中MPM患者经常产生耐药性，但其相关的耐药机制尚不清楚。本研究旨在阐明MPM细胞系对PMX耐药的潜在机制。我们发现，在与耐药相关的差异表达基因（通过RNA测序确定）中，TYMS在已建立的耐药细胞系中的表达高于亲本细胞系。敲低TYMS表达显著降低了耐药细胞系中的耐药性。相反，TYMS过表达显著增加了亲本细胞中的耐药性。代谢组学分析显示，耐药细胞系中dTMP的水平高于亲本细胞系；然而，耐药细胞在PMX处理后dTTP水平没有变化。我们发现核酸生物合成途径对于预测PMX在MPM细胞中的疗效很重要。染色质免疫沉淀-定量聚合酶链反应（ChIP-qPCR）分析结果表明，TYMS 5'-UTR中的H3K27乙酰化可能促进其在耐药细胞中的表达。我们的研究结果表明，dTMP的细胞内水平是MPM患者有效治疗的潜在生物标志物，并提示TYMS表达调控机制在该疾病中的重要性。
