谷糠结合态多酚通过miRNA-149逆转结肠癌多药耐药的活性成分及分子机制

Foxtail millet (Setaria italica) is an annual plant, and millet bran is naturally rich by-product produced during the milling of millet. Previous studies had shown that polyphenols in millet bran exhibited significant anti-tumor effects. Multidrug resistance（MDR）is a biggest problem of tumor therapy, and miRNAs play key roles in the MDR regulation. Currently, we uncover that bound polyphenol of inner shell（BPIS）from millet bran can reverse the multidrug resistance of colon cancer cells (CRC) by up-regulating the miRNA-149 expression. Therefore, this project aims to explore the active constituents that display the MDR reversal of CRC in BPIS by miR-149 and its molecular mechanism. The contents are as follows: analyzing the chemical components of BPIS and identifying the compound structures by various chromatographic techniques; Confirming the active ingredient in BPIS that possesses the MDR reversal of CRC both in vitro and in vivo, named BPIS-R; Investigating the main way that BPIS-R regulates the expression level of miR-149; Screening the target genes of miR-149 to regulate the MDR of colon cancer; Constructing the stable MDR cell and nude mouse models by knock-outing or over-expressing target gene to determine the key role of its in mediating the MDR reversal of CRC by BPIS-R-induced.

谷子（Setaria italica）属一年生禾本科植物，谷糠是谷子加工成小米的过程中脱下的副产品，有研究表明谷糠源多酚具显著的抗肿瘤功效。肿瘤多药耐药是肿瘤治疗的最大难题之一，而miRNAs在调控肿瘤耐药网络中扮演了关键角色。本课题组研究发现，谷糠结合态多酚BPIS能够通过上调miRNA-149逆转结肠癌的多药耐药性。因此，本项目拟探讨BPIS中通过miR-149逆转结肠癌耐药的活性成分及分子机制。研究内容包括：采用多种色谱技术分析BPIS成分并鉴定单体结构；用结肠癌多药耐药细胞和裸鼠模型确定BPIS中逆转结肠癌耐药的活性成分，BPIS-R；从转录因子及表观遗传学两个方面探讨BPIS-R对miR-149表达水平的调控方式；筛查miR-149调控结肠癌多药耐药的靶基因；构建敲除或过表达该靶基因的多药耐药细胞和裸鼠模型，确定其介导BPIS-R逆转结肠癌多药耐药的关键角色。

肿瘤多药耐药是肿瘤治疗的难题之一，miRNAs在调控肿瘤耐药网络中扮演了重要角色。本项目主要探讨了谷糠结合态多酚BPIS调控miR-149逆转结肠癌耐药的活性成分及分子机制。研究发现BPIS能够显著逆转结肠癌多药耐药株HCT-8/Fu细胞的耐药能力，且阿魏酸和对香豆酸为其中主要活性成分；他们通过抑制结肠癌耐药株HCT-8/Fu增殖，诱导细胞凋亡，增加胞内药物积蓄和下调耐药蛋白的方式来逆转结肠癌耐药；BPIS在裸鼠耐药模型中同样能发挥显著的逆转耐药作用。机制研究揭示：1.BPIS及其活性成分一方面在转录水平抑制c-Myc表达进而上调miR-149，另一方面通过抑制miR-149 CpG岛的甲基化从而增加miR-149的表达。2.miR-149逆转结肠癌耐药的下游靶基因是AKT和FOXM1，这两种转录因子通过下调多药耐药蛋白P-gp、BCRP的表达逆转结肠癌耐药。3.miR-149通过抑制靶基因AKT的表达，阻滞其下游NEU3介导的神经节甘脂代谢，进而逆转结肠癌细胞的化疗耐药。在扩展研究内容中发现：BPIS能够恢复小鼠肠道菌群结构的丰富度和多样性，抑制AOM/DSS诱导的小鼠模型炎性结肠癌发生发展；BPIS中的主要活性成分阿魏酸和对香豆酸可以通过下调lncRNA495810在结肠癌中异常表达，发挥抗结肠癌效应。这些研究结果揭示了miR-149和下游靶基因FOXM1、AKT在介导BPIS逆转结肠癌多药耐药中的重要作用。本研究从植物多酚调控miRNAs的角度，阐释了BPIS逆转结肠癌多药耐药性的活性组分及分子机制，为谷糠活性多酚在结肠癌耐药逆转剂的研发提供了扎实的理论数据。