Guo Yue, Shu Limin, Zhang Chengyue, Su Zheng-Yuan, Kong Ah-Ng Tony
Graduate Program in Pharmaceutical Sciences, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Room 228, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA.
Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Room 228, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA.
Biochem Pharmacol. 2015 Mar 15;94(2):69-78. doi: 10.1016/j.bcp.2015.01.009. Epub 2015 Jan 29.
Colorectal cancer remains the most prevalent malignancy in humans. The impact of epigenetic alterations on the development of this complex disease is now being recognized. The dynamic and reversible nature of epigenetic modifications makes them a promising target in colorectal cancer chemoprevention and treatment. Curcumin (CUR), the major component in Curcuma longa, has been shown as a potent chemopreventive phytochemical that modulates various signaling pathways. Deleted in lung and esophageal cancer 1 (DLEC1) is a tumor suppressor gene with reduced transcriptional activity and promoter hypermethylation in various cancers, including colorectal cancer. In the present study, we aimed to investigate the inhibitory role of DLEC1 in anchorage-independent growth of the human colorectal adenocarcinoma HT29 cells and epigenetic regulation by CUR. Specifically, we found that CUR treatment inhibited colony formation of HT29 cells, whereas stable knockdown of DLEC1 using lentiviral short hairpin RNA vector increased cell proliferation and colony formation. Knockdown of DLEC1 in HT29 cells attenuated the ability of CUR to inhibit anchorage-independent growth. Methylation-specific polymerase chain reaction (MSP), bisulfite genomic sequencing, and methylated DNA immunoprecipitation revealed that CUR decreased CpG methylation of the DLEC1 promoter in HT29 cells after 5 days of treatment, corresponding to increased mRNA expression of DLEC1. Furthermore, CUR decreased the protein expression of DNA methyltransferases and subtypes of histone deacetylases (HDAC4, 5, 6, and 8). Taken together, our results suggest that the inhibitory effect of CUR on anchorage-independent growth of HT29 cells could, at least in part, involve the epigenetic demethylation and up-regulation of DLEC1.
结直肠癌仍然是人类中最常见的恶性肿瘤。表观遗传改变对这种复杂疾病发展的影响目前正在得到认可。表观遗传修饰的动态和可逆性质使其成为结直肠癌化学预防和治疗中有前景的靶点。姜黄素（CUR）是姜黄中的主要成分，已被证明是一种有效的化学预防植物化学物质，可调节各种信号通路。肺癌和食管癌缺失基因1（DLEC1）是一种肿瘤抑制基因，在包括结直肠癌在内的各种癌症中其转录活性降低且启动子高度甲基化。在本研究中，我们旨在研究DLEC1对人结直肠腺癌HT29细胞非锚定依赖性生长的抑制作用以及姜黄素的表观遗传调控。具体而言，我们发现姜黄素处理可抑制HT29细胞的集落形成，而使用慢病毒短发夹RNA载体稳定敲低DLEC1可增加细胞增殖和集落形成。在HT29细胞中敲低DLEC1减弱了姜黄素抑制非锚定依赖性生长的能力。甲基化特异性聚合酶链反应（MSP）、亚硫酸氢盐基因组测序和甲基化DNA免疫沉淀显示，处理5天后姜黄素降低了HT29细胞中DLEC1启动子的CpG甲基化，这与DLEC1的mRNA表达增加相对应。此外，姜黄素降低了DNA甲基转移酶和组蛋白去乙酰化酶亚型（HDAC4、5、6和8）的蛋白表达。综上所述，我们的结果表明，姜黄素对HT29细胞非锚定依赖性生长的抑制作用至少部分可能涉及DLEC1的表观遗传去甲基化和上调。
