Luteolin impacts deoxyribonucleic acid repair by modulating the mitogen-activated protein kinase pathway in colorectal cancer

This study aimed to investigate the effects of luteolin on colorectal cancer (CRC) and explore its underlying mechanism. HCT-116 and HT-29 cells were treated with luteolin, cisplatin, or selumetinib. The cell survival, cell proliferation, apoptosis and cell cycle distribution, and DNA damage were detected using Cell Counting Kit-8, colony formation, flow cytometry, and immunofluorescence staining analysis, respectively. Western blotting was used to detect the expression of apoptosis-related, cycle-related, DNA-damage-related, and mitogen-activated protein kinase (MAPK) pathway-related proteins. Luteolin showed inhibitory effects on cellular growth by reducing cell survival and proliferation, inducing apoptosis and DNA damage, and arresting the cell cycle in a concentration-dependent manner in HCT-116 and HT-29 cells. Meanwhile, luteolin increased the expression of pro-apoptotic proteins, p-CHK1 (central to the induction of cell cycle arrest), and DNA excision repair protein and decreased anti-apoptotic proteins, G2-M phase-related proteins, and DNA repair proteins. The combination of cisplatin and luteolin significantly decreased cell survival and increased the apoptosis rate of HCT-116 and HT-29 cells compared with cisplatin alone. Bioinformatic analysis using the Comparative Toxicogenomics Database and STITCH and MalaCards databases showed that the MAPK pathway is involved in the pharmacology of luteolin. Furthermore, western blotting demonstrated that luteolin plays an inhibitory role by suppressing the MAPK signaling pathway in CRC, which is enhanced when combined with selumetinib. Luteolin can also prevent tumourigenesis in CRC in vivo. In conclusion, luteolin suppressed cell proliferation, blocked the cell cycle, and induced DNA damage and apoptosis progression in CRC cells by mediating the MAPK pathway

本研究旨在探究木犀草素（luteolin）对结直肠癌（colorectal cancer, CRC）的作用，并揭示其潜在分子机制。采用木犀草素、顺铂（cisplatin）或司美替尼（selumetinib）分别处理HCT-116与HT-29细胞。通过细胞计数试剂盒-8（Cell Counting Kit-8）、集落形成实验、流式细胞术（flow cytometry）及免疫荧光染色（immunofluorescence staining）分析，分别检测细胞存活率、细胞增殖能力、细胞凋亡与细胞周期分布，以及DNA损伤情况。采用蛋白质印迹法（Western blotting）检测凋亡相关、周期相关、DNA损伤相关及丝裂原活化蛋白激酶（mitogen-activated protein kinase, MAPK）通路相关蛋白的表达水平。在HCT-116与HT-29细胞中，木犀草素可通过浓度依赖性方式降低细胞存活率与增殖能力、诱导细胞凋亡与DNA损伤、阻滞细胞周期，从而发挥细胞生长抑制作用。同时，木犀草素可上调促凋亡蛋白、介导细胞周期阻滞的关键蛋白p-CHK1及DNA切除修复蛋白的表达，下调抗凋亡蛋白、G2/M期相关蛋白与DNA修复蛋白的表达。与单独使用顺铂相比，顺铂联合木犀草素可显著降低HCT-116与HT-29细胞的存活率，并提高细胞凋亡率。通过比较毒理基因组学数据库（Comparative Toxicogenomics Database）、STITCH数据库及MalaCards数据库开展生物信息学分析，结果显示MAPK通路参与木犀草素的药理作用过程。进一步的蛋白质印迹实验证实，木犀草素可通过抑制结直肠癌细胞中的MAPK信号通路发挥抗肿瘤作用，且该抑制效果在与司美替尼联合使用时得以增强。木犀草素在体内亦可抑制结直肠癌的肿瘤发生。综上，木犀草素可通过调控MAPK通路，抑制结直肠癌细胞增殖、阻滞细胞周期、诱导DNA损伤与细胞凋亡进程。