The miRNA125a-5p and miRNA125b-1-5p cluster induces cell invasion by down-regulating DDB2-reduced epithelial-to-mesenchymal transition (EMT) in colorectal cancer

Fang Zhu; Juan Wei; Danni He; Jing He; Ling Liu; Huyang Hou; Hengmei Shi; Shidai Jin; Jun Li; Xiaoyan Shi; Ping Liu; Mao Huang

doi:10.21037/jgo-22-1222

The miRNA125a-5p and miRNA125b-1-5p cluster induces cell invasion by down-regulating DDB2-reduced epithelial-to-mesenchymal transition (EMT) in colorectal cancer

J Gastrointest Oncol. 2022 Dec;13(6):3112-3122. doi: 10.21037/jgo-22-1222.

Authors

Fang Zhu^#^{1

2}, Juan Wei^#², Danni He^#³, Jing He¹, Ling Liu⁴, Huyang Hou³, Hengmei Shi³, Shidai Jin¹, Jun Li¹, Xiaoyan Shi³, Ping Liu¹, Mao Huang¹

Affiliations

¹ Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
² Department of Oncology, Nanjing Second Hospital, Nanjing University of Chinese Medicine, Nanjing, China.
³ Department of Gynecology, Women's Hospital of Nanjing Medical University (Nanjing Maternity and Child Health Care Hospital), Nanjing, China.
⁴ Biomedical Institute Department, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.

^# Contributed equally.

Abstract

Background: MicroRNA (miRNA) is a kind of non-coding RNA that regulates gene expression and is involved in tumor development. MiRNA-125 is reportedly aberrantly expressed in colorectal cancer tissue; however, its potential function and underlying mechanism remain unclear. The present study aimed to investigate the expression level and potential role of the miRNA-125 family in the invasion and migration of colorectal cancer.

Methods: To further understand the role of the miRNA-125 family in metastatic colorectal cancer, we overexpressed miRNA-125 in the SW480 cell line by transfection with the miRNA-125 family mimics or a sponge. Methyl thiazolyl tetrazolium (MTT) assay was performed to identify the effect of the miRNA-125 family on cell proliferation, and a Transwell filter assay was used to detect the role of the miRNA-125 family in migration and invasion. A luciferase assay was carried out to confirm the binding site of miRNA-125 and the target gene, damage specific DNA binding protein 2 (DDB2). Western blot was applied to detect the expression levels of DDB2 and the markers of epithelial-to-mesenchymal transition (EMT) in colorectal cancer cells.

Results: The real-time polymerase chain reaction (PCR) results showed that miR-125a-5p and miR-125b-1-5p were up-regulated in metastatic colorectal cancer tissues. The Transwell filter assay results appeared that miR-125a-5p and miR-125b-1-5p could promote the invasion and migration of colorectal cancer cells. The luciferase assay data confirmed the binding site of miR-125a-5p and miR-125b-1-5p on the 3' untranslated region (3'UTR) of DDB2 messenger RNA (mRNA). The real-time PCR and Western blot results indicated that miR-125a-5p and miR-125b-1-5p could regulate the expression levels of DDB2 and EMT markers, and lower DDB2 expression was observed in metastatic tissues.

Conclusions: Our findings illustrated that miRNA125a-5p and miRNA125b-1-5p could reduce the expression of DDB2 by binding to the 3'UTR region, and then regulate the expression levels of EMT markers, leading to the enhanced invasion and metastasis of colorectal cancer cells. Thus, miRNA125a-5p and miRNA125b-1-5p might be novel markers of colorectal cancer migration and potential therapeutic targets to treat metastatic colorectal cancer patients.

Keywords: Colorectal cancer (CRC); damage specific DNA binding protein 2 (DDB2); endothelial-to-mesenchymal transition; metastases; miRNA-125.