Abstract：
5-Fluorouracil is a commonly used chemotherapy drug for colorectal cancer. Resistance to 5-Fluorouracil remains a challenge. This research aimed to explore the mechanism of 5-Fluorouracil resistance in colorectal cancer. RT-qPCR and Western blot were used to determine the RNA and protein expression in both cells and exosome. Assays in vitro and in vivo were performed to measure the role of miR-149-5p in colorectal cancer cells. RIP, luciferase activity report, and RNA pulldown assay were applied to detect the association of PTOV1-AS1, SUV39H1, miR-149-5p, and FOXM1. MiR-149-5p was down-expressed in 5-Fluorouracil-resistant cells. MiR-149-5p enhanced the effectiveness of 5-Fluorouracil both in vitro and in vivo. Sensitive colorectal cancer cells released exosomal miR-149-5p to sensitize resistant cells to chemotherapy. Mechanistically, miR-149-5p targeted the FOXM1 to inactivate Wnt/β-catenin pathway, and PTOV1-AS1 recruited SUV39H1 to suppress miR-149-5p transcription, in turn activating Wnt/β-catenin pathway, and forming a positive feedback loop with FOXM1. PTOV1-AS1 inhibits miR-149-5p by a positive feedback loop with FOXM1-mediated Wnt/β-catenin pathway, which provides insights into a potential novel target for enhancing the effectiveness of chemotherapy in colorectal cancer patients.
摘要：
5-氟尿嘧啶是结直肠癌常用的化疗药物。对5-氟尿嘧啶的抗性仍然是一个挑战。本研究旨在探讨结直肠癌对5-氟尿嘧啶的耐药机制。RT-qPCR和Western印迹用于确定细胞和外泌体中的RNA和蛋白质表达。进行体外和体内测定以测量miR-149-5p在结直肠癌细胞中的作用。RIP,荧光素酶活性报告,并应用RNA下拉试验检测PTOV1-AS1、SUV39H1、miR-149-5p、FOXM1MiR-149-5p在5-氟尿嘧啶抗性细胞中下调表达。MiR-149-5p在体外和体内都增强了5-氟尿嘧啶的有效性。敏感结直肠癌细胞释放外泌体miR-149-5p以使耐药细胞对化疗敏感。机械上,miR-149-5p靶向FOXM1使Wnt/β-catenin通路失活,和PTOV1-AS1招募SUV39H1来抑制miR-149-5p转录，进而激活Wnt/β-catenin通路，并与FOXM1形成正反馈回路。PTOV1-AS1通过FOXM1介导的Wnt/β-catenin通路的正反馈回路抑制miR-149-5p,这为提高结直肠癌患者化疗效果的潜在新靶点提供了见解。
