Li Ji, Xiang Qing, Wang Mei, Zhang Hongchang, Liang Rong
Department of Pharmacy, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, Qingdao, Shandong 266035, China.
Department of Emergency, Rizhao Hospital of TCM, Rizhao 276800, China.
J Oncol. 2021 Jul 19;2021:5338934. doi: 10.1155/2021/5338934. eCollection 2021.
Colorectal carcinoma (CRC), a life-threatening malignancy, has been found to present resistance to 5-fluorouracil (5-FU) and cause a poor prognosis for patients. Previous studies have proved that all-trans retinoic acid (ATRA) could inhibit the development of CRC cells. In addition, miR-378c was discovered to exert a vital role in various cancers. In this study, we utilized MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), transwell assay, and flow cytometry to confirm that ATRA was able to enhance the inhibitory effects of 5-FU on HCT116 cells effectively by promoting cell apoptosis. Then, ENCORI database (http://starbase.sysu.edu.cn/) was employed to predict that miR-378c was downregulated dramatically in CRC and E2F7 was the direct target of miR-378c. QRT-PCR (quantitative real-time polymerase chain reaction) was conducted to verify that the expression level of miR-378c was decreased while E2F7 expression was upregulated in CRC tissues compared with para-carcinoma tissues. Additionally, treatment of 5-FU combined with ATRA could increase miR-378c expression, whereas it decreased the expression of E2F7. Dual-Luciferase Reporter assay results revealed that miR-378c could regulate the load of E2F7 by binding to its 3'UTR directly. Furthermore, miR-378c inhibitor or vector with E2F7 partially counteracted the effects of 5-FU combined with ATRA on viability, migration, invasion, and apoptosis of HCT116 cells. In conclusion, our study aims to confirm that ATRA enhances chemosensitivity to 5-FU of patients with CRC and expound the potential molecular mechanisms.
结直肠癌（CRC）是一种危及生命的恶性肿瘤，已发现其对5-氟尿嘧啶（5-FU）具有耐药性，导致患者预后不良。先前的研究证明，全反式维甲酸（ATRA）可以抑制CRC细胞的发展。此外，发现miR-378c在各种癌症中发挥重要作用。在本研究中，我们利用MTT（3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐）、Transwell实验和流式细胞术来证实ATRA能够通过促进细胞凋亡有效增强5-FU对HCT116细胞的抑制作用。然后，利用ENCORI数据库（http://starbase.sysu.edu.cn/）预测miR-378c在CRC中显著下调，且E2F7是miR-378c的直接靶点。进行QRT-PCR（定量实时聚合酶链反应）以验证与癌旁组织相比，CRC组织中miR-378c的表达水平降低而E2F7表达上调。此外，5-FU联合ATRA治疗可增加miR-378c表达，而降低E2F7表达。双荧光素酶报告基因检测结果显示，miR-378c可通过直接结合其3'UTR来调节E2F7的负载。此外，miR-378c抑制剂或含E2F7的载体部分抵消了5-FU联合ATRA对HCT116细胞活力、迁移、侵袭和凋亡的影响。总之，我们的研究旨在证实ATRA增强CRC患者对5-FU的化疗敏感性并阐述潜在的分子机制。
