MicroRNA-421 Inhibits Apoptosis by Downregulating Caspase-3 in Human Colorectal Cancer

Abstract

Yifan Zhou,1,* Xiaowen Cheng,1,2,* Yufeng Wan,3,* Tingting Chen,4 Qing Zhou,2 Zhengguang Wang,5 Huaqing Zhu2 1Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, People’s Republic of China; 2Laboratory of Molecular Biology and Department of Biochemistry, Anhui Medical University, Hefei, Anhui 230022, People’s Republic of China; 3Department of Otolaryngology, The Affiliated Chaohu Hospital of Anhui Medical University, Hefei, Anhui 238001, People’s Republic of China; 4Department of Pathology, Anhui Medical University, Hefei, Anhui 230032, People’s Republic of China; 5Department of Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, People’s Republic of China*These authors contributed equally to this workCorrespondence: Zhengguang WangThe First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, People’s Republic of ChinaEmail [email protected] ZhuLaboratory of Molecular Biology and Department of Biochemistry, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, People’s Republic of ChinaEmail [email protected]: Dysregulated microRNAs (miRNAs/miRs) have been reported to play significant roles in pathogenesis of colorectal cancer (CRC). Previous studies have demonstrated that miR-421 regulates apoptosis in some cancers. Caspase-3 plays a key role in apoptosis, but the relationship between miR-421 and caspase-3 in CRC has not been determined. In this study, we investigated the role of miR-421 in CRC and the relationship between miR-421 and caspase-3.Methods: Expression of miR-421 and caspase-3 were detected in human paired CRC cancer tissues and corresponding paracancerous tissues. In situ detection of tissue, apoptosis was performed via the TUNEL assay. HCT116 and SW480 cell lines were subjected to several in vitro experiments to explore the relationship between miRNA421 and caspase-3 during apoptosis using miR421 mimics/antagomir and luciferase reporter assay. Apoptosis was measured by determining the levels and activity of caspase-3 as well as DNA fragmentation. Luciferase reporter assay was performed to determine the potential interaction of miR-421 with caspase-3.Results: The results showed that the expression of miR-421 in cancer tissues was higher than that in corresponding paracancerous tissues. Inhibition of miR-421 induced apoptosis, as shown by the upregulation of caspase-3 activity and expression as well as DNA fragmentation, which were attenuated by miR-421 mimic. We further showed that miR-421 targeted and inhibited CASP3 expression by targeting sites located in the 3ʹ-untranslated region (3ʹ-UTR) of CASP3 mRNA.Conclusion: This study demonstrated an anti-apoptotic role of miR-421 in CRC and identified caspase-3 gene as a direct target of miR-421. These findings provide a potential treatment strategy using miR-421 as a therapeutic target for CRC.Keywords: microRNA-421, colorectal cancer, apoptosis, caspase-3

Keywords

• microrna-421
• colorectal cancer
• apoptosis
• caspase-3