Natarajan Kasthuri, Abraham Premila, Kota Rekha
Department of Biochemistry, Christian Medical College Campus, Vellore, Tamil Nadu, India.
Department of Pathology, Madha Medical College Thandalam, Chennai, Tamil Nadu, India.
Cell Biochem Funct. 2017 Oct;35(7):378-391. doi: 10.1002/cbf.3285. Epub 2017 Sep 4.
The efficacy of methotrexate (MTX), a commonly used chemotherapeutic drug, is limited by intestinal injury. As the mechanism of MTX-induced small intestinal injury is not clear, there is no definitive treatment for MTX-induced gastrointestinal injury. The present study investigates the role of mitochondrial apoptotic pathway in MTX-induced small intestinal injury and examines whether aminoguanidine is effective in preventing the damage. Eight Wistar rats were administered 3 consecutive i.p. injections of 7 mg/kg body wt. MTX. Some rats were pretreated with 30 mg or 50 mg/kg body wt. of aminoguanidine (n = 6 in each group). Protein expressions of cytochrome c, caspases 3 and 9, and PARP-1 were determined in the small intestines by immunohistochemistry and western blot. Mitochondrial pathway of apoptosis was activated in the small intestines of MTX-treated rats as evidenced by intense immunostaining for cyt c, caspases 9 and 3, and PARP-1 and mitochondrial release of cyt c, activation of caspases, and PARP-1 cleavage by Western blot. Immunofluorescence revealed increased nuclear localization of PARP-1. Aminoguanidine pretreatment ameliorated MTX-induced small intestinal injury in dose-dependent manner and inactivated the mitochondrial apoptotic pathway. Aminoguanidine may possess beneficial intestinal protective effects as an adjuvant co-drug against MTX intestinal toxicity during cancer chemotherapy. As the mechanism of MTX-induced small intestinal injury is not clear, there is no definitive treatment for MTX-induced gastrointestinal injury. The results of the present study show that the mitochondrial pathway of apoptosis plays a role in MTX-induced small intestinal injury as evidenced by cytochrome c release, activation of caspases 9 and 3, PARP-1 cleavage, and DNA fragmentation. Aminoguanidine (AG) pretreatment attenuates the severity of small-intestinal injury induced in rats by MTX treatment. The mechanisms of action of AG involve inhibition of iNOS, and mitochondrial pathway of apoptosis. It is suggested that aminoguanidine may possess beneficial intestinal protective effects as an adjuvant co-drug against MTX intestinal toxicity during cancer chemotherapy.
常用化疗药物甲氨蝶呤（MTX）的疗效受肠道损伤限制。由于MTX所致小肠损伤的机制尚不清楚，因此对于MTX引起的胃肠道损伤尚无确切的治疗方法。本研究探讨线粒体凋亡途径在MTX所致小肠损伤中的作用，并检验氨基胍是否能有效预防这种损伤。8只Wistar大鼠连续3次腹腔注射7mg/kg体重的MTX。部分大鼠预先给予30mg或50mg/kg体重的氨基胍（每组n = 6）。通过免疫组织化学和蛋白质印迹法测定小肠中细胞色素c、半胱天冬酶3和9以及PARP-1的蛋白表达。MTX处理大鼠的小肠中凋亡的线粒体途径被激活，细胞色素c、半胱天冬酶9和3以及PARP-1的强烈免疫染色以及细胞色素c的线粒体释放、半胱天冬酶的激活和蛋白质印迹法检测的PARP-1裂解均证明了这一点。免疫荧光显示PARP-1的核定位增加。氨基胍预处理以剂量依赖的方式改善了MTX所致的小肠损伤，并使线粒体凋亡途径失活。在癌症化疗期间，氨基胍作为辅助联合药物可能对MTX肠道毒性具有有益的肠道保护作用。由于MTX所致小肠损伤的机制尚不清楚，因此对于MTX引起的胃肠道损伤尚无确切的治疗方法。本研究结果表明，凋亡的线粒体途径在MTX所致小肠损伤中起作用，细胞色素c释放、半胱天冬酶9和3的激活、PARP-1裂解以及DNA片段化证明了这一点。氨基胍（AG）预处理减轻了MTX处理诱导的大鼠小肠损伤的严重程度。AG的作用机制包括抑制诱导型一氧化氮合酶和凋亡的线粒体途径。提示在癌症化疗期间，氨基胍作为辅助联合药物可能对MTX肠道毒性具有有益的肠道保护作用。
