Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto 606-8507, Japan.
Int J Oncol. 2012 Jul;41(1):24-30. doi: 10.3892/ijo.2012.1461. Epub 2012 May 2.
Pemetrexed (PEM) is a novel, multitargeted, antifolate, antineoplastic agent for the treatment of non-small cell lung cancer and malignant pleural mesothelioma. Additional effects of nitric oxide (NO) donors on the chemosensitivity of cancers have been reported. However, the effects of an NO donor on PEM-induced cytotoxicity remain unknown. In this study, we investigated the effects of the NO donors, NOC-18 on the cytotoxicity in A549 cells in vitro and of nitroglycerin (GTN), on the tumor growth of Lewis lung carcinoma cells in a murine syngraft model treated with PEM. The effects of NO donors on the expression of proteins associated with PEM metabolism, including thymidylate synthase (TS), reduced folate carrier 1 (RFC1), folylpolyglutamate synthase (FPGS), γ-glutamyl hydrolase (GGH) and multidrug resistance-related protein (MRP)5, and the effects of cyclic guanosine mono-phosphate (cGMP) signaling on these proteins were examined in A549 cells. Treatment with 100 nM NOC-18 for 3 days significantly enhanced PEM-induced cytotoxicity and increased the expression of RFC1 and FPGS in A549 cells. Treatment with 10 nM 8-bromo-cGMP (8-Br-cGMP) for 3 days also increased the expression of RFC1 and FPGS in A549 cells. 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (10 µm) significantly reversed the increase in RFC1 and FPGS expression induced by 100 nM NOC-18 in A549 cells. Combination therapy with GTN and PEM significantly reduced tumor growth compared with PEM alone in the syngraft model. The enhanced antitumor effect of GTN plus PEM was significantly reversed by the concomitant addition of ODQ. These findings suggest that NO donors, such as NOC-18 and GTN, enhance the anticancer effects of PEM by increasing the RFC1 and FPGS expression and stimulating cGMP signaling pathways in cancer cells.
培美曲塞（PEM）是一种新型、多靶点、抗叶酸、抗肿瘤药物，用于治疗非小细胞肺癌和恶性胸膜间皮瘤。已有报道称，一氧化氮（NO）供体对癌症的化疗敏感性具有额外的影响。然而，NO 供体对 PEM 诱导的细胞毒性的影响尚不清楚。在这项研究中，我们研究了 NO 供体 NOC-18 对体外 A549 细胞中 PEM 细胞毒性的影响，以及 GTN（硝化甘油）对 PEM 处理的Lewis 肺癌细胞在小鼠同种异体移植模型中肿瘤生长的影响。NO 供体对与 PEM 代谢相关的蛋白表达的影响，包括胸苷酸合成酶（TS）、还原叶酸载体 1（RFC1）、叶酰多聚谷氨酸合成酶（FPGS）、γ-谷氨酰水解酶（GGH）和多药耐药相关蛋白 5（MRP）5，并检查了 cGMP 信号通路对这些蛋白的影响，A549 细胞。用 100 nM NOC-18 处理 3 天可显著增强 PEM 诱导的细胞毒性，并增加 A549 细胞中 RFC1 和 FPGS 的表达。用 10 nM 8-溴-cGMP（8-Br-cGMP）处理 3 天也可增加 A549 细胞中 RFC1 和 FPGS 的表达。1H-[1,2,4]恶二唑[4,3-a]喹喔啉-1-酮（ODQ）（10 µm）可显著逆转 100 nM NOC-18 诱导的 A549 细胞中 RFC1 和 FPGS 表达的增加。与单独使用 PEM 相比，GTN 与 PEM 的联合治疗在同种异体移植模型中显著减少肿瘤生长。GTN 加 PEM 的增强抗肿瘤作用可通过同时添加 ODQ 显著逆转。这些发现表明，NO 供体，如 NOC-18 和 GTN，通过增加 RFC1 和 FPGS 的表达和刺激癌细胞中的 cGMP 信号通路来增强 PEM 的抗癌作用。
