Chen Jiaqi, Ying Yongli, Zhu Hongjun, Zhu Tingjun, Qu Chunsheng, Jiang Jinhong, Fang Bingmu
Clinical Laboratory, Lishui People's Hospital, Sixth Affiliated Hospital of Wenzhou Medical University, Lishui, Zhejiang 323000, P.R. China.
Department of Surgery, Lishui People's Hospital, Sixth Affiliated Hospital of Wenzhou Medical University, Lishui, Zhejiang 323000, P.R. China.
Oncol Lett. 2019 Jan;17(1):1108-1114. doi: 10.3892/ol.2018.9662. Epub 2018 Nov 5.
Curcumin, a polyphenol derived from the rhizome of , is a potential tumor inhibitor through affecting signaling pathways and epigenetic regulation. The mammalian target of rapamycin (mTOR) gene serves a crucial role in the carcinogenesis of multiple myeloma. The curcumin-induced epigenetic regulation of mTOR, including promoter DNA methylation in multiple myeloma, has not yet been fully elucidated. In the present study, antitumor effects of curcumin were investigated in RPMI-8226 and NCI-H929 cells using an MTT assay and flow cytometry. The expression of mTOR and DNA methyltransferase proteins were determined by western blot analysis, and the methylation status of the mTOR promoter were detected by sequencing following bisulfite conversion. The results of the present study revealed that the half-maximal inhibitory concentration of curcumin was 10 µM in myeloma cells. Following curcumin treatment, the mRNA and protein expression levels of mTOR were decreased by 43.31 and 39.34% in NCI-H929 cells, respectively. The promoter of mTOR, located in chromosome 1 (chromosome position, 11262153-11263153), contains a CpG island that was hypermethylated in myeloma cells following curcumin treatment. The expression levels of DNA methyltransferase (DNMT)3a and DNMT3b were increased in curcumin-treated cells. Collectively, these results indicate that curcumin serves a role in the epigenetic regulation of mTOR expression, and that mTOR downregulation is due to promoter hypermethylation, which may be associated with DNMT3a and DNMT3b upregulation. The results of the present study contribute towards improving the understanding of curcumin treatment in multiple myeloma and provide novel insights into the molecular mechanisms underlying the epigenetic regulation of mTOR.
姜黄素是一种从姜黄根茎中提取的多酚，通过影响信号通路和表观遗传调控，是一种潜在的肿瘤抑制剂。雷帕霉素靶蛋白（mTOR）基因在多发性骨髓瘤的致癌过程中起关键作用。姜黄素诱导的mTOR表观遗传调控，包括多发性骨髓瘤中启动子DNA甲基化，尚未完全阐明。在本研究中，使用MTT法和流式细胞术研究了姜黄素在RPMI-8226和NCI-H929细胞中的抗肿瘤作用。通过蛋白质印迹分析测定mTOR和DNA甲基转移酶蛋白的表达，并在亚硫酸氢盐转化后通过测序检测mTOR启动子的甲基化状态。本研究结果显示，姜黄素在骨髓瘤细胞中的半数最大抑制浓度为10μM。姜黄素处理后，NCI-H929细胞中mTOR的mRNA和蛋白表达水平分别降低了43.31%和39.34%。mTOR启动子位于1号染色体（染色体位置，11262153-11263153），包含一个CpG岛，在姜黄素处理后的骨髓瘤细胞中该岛发生了高甲基化。姜黄素处理的细胞中DNA甲基转移酶（DNMT）3a和DNMT3b的表达水平升高。总体而言，这些结果表明姜黄素在mTOR表达的表观遗传调控中起作用，mTOR的下调是由于启动子高甲基化，这可能与DNMT3a和DNMT3b的上调有关。本研究结果有助于增进对姜黄素治疗多发性骨髓瘤的理解，并为mTOR表观遗传调控的分子机制提供新的见解。
