MiR-23a transcriptional activated by Runx2 increases metastatic potential of mouse hepatoma cell via directly targeting Mgat3

Huang Huang,Peishan Yu,Shujing Wang,Jianing Zhang,Yanjie Guo,Wenli Li,Yubo Liu,Jianhua Qu

doi:10.1038/s41598-018-25768-z

Abstract

MicroRNAs (miRNAs) and aberrant glycosylation both play important roles in tumor metastasis. In this study, the role of miR-23a in N-glycosylation and the metastasis of mouse hepatocellular carcinoma (HCC) cells was investigated. The miRNA expression array profiles that were confirmed by qPCR and Western blot analyses revealed higher miR-23a expression levels in Hca-P cells (with lymphatic metastasis potential) than in Hepa1–6 cells (with no lymphatic metastasis potential), while the expression of mannoside acetylglucosaminyltransferase 3 (Mgat3) was negatively associated with metastasis potential. Mgat3 is a key glycosyltransferase in the synthesis of the bisecting (β1,4GlcNAc branching) N-glycan structure. Bioinformatics analysis indicated that Mgat3 may be a target of miR-23a, and this hypothesis was verified by dual-luciferase reporter gene assays. Furthermore, we found that the transcription factor Runx2 can directly bind to the miR-23a gene promoter and promote its expression, as shown in dual-luciferase reporter gene assays and ChIP assays. Collectively, these results indicate that miR-23a might increase the metastatic potential of mouse HCC by affecting the branch formation of N-glycan chains presented on the cell surface through the targeting of the glycosyltransferase Mgat3. These findings may provide insight into the relationship between abnormal miRNA expression and aberrant glycosylation during tumor lymphatic metastasis.

Highlights

The majority of cancer-related deaths are attributed to the metastatic spread of cancer cells to vital organs rather than to primary tumor outgrowth
One widespread glycosylation change that promotes malignancy is the enhanced formation of β1,6-N-acetylglucosamine (β1,6GlcNAc) side chains caused by increased mannoside acetylglucosaminyltransferase 5 (Mgat5) activity and counteracting β1,4GlcNAc branching of N-linked structures synthesized by Mgat[33]
Our miRNA microarray analyses showed that miR-23a expression levels were significantly higher in Hca-P cells than in Hepa[1,2,3,4,5,6] cells[27], while the relative expressions of miR23a were higher than several tumor malignancy related miRNAs9,10,16,20,21,28,29 in the two mouse hepatocellular carcinoma (HCC) cell lines (Fig. 1a)

Summary

Introduction

The majority of cancer-related deaths are attributed to the metastatic spread of cancer cells to vital organs rather than to primary tumor outgrowth. Brian E et al reported that elevated serum miR-16, miR-378, and sICAM1 levels correlate with bone metastasis[13] These findings highlight the potential of miRNA profiling in cancer therapeutic decision-making and in the diagnosis of tumor metastasis. Given the important roles of miRNA and glycosylation of glycoproteins and glycolipids in malignancy, it is conceivable that miRNAs may play an important role in tumor progression by targeting specific glycosyltransferase that catalyze the formation of specific glycan structures. Some enzymes involved in protein glycosylation have been reported to be targets of cancer relevant miRNAs. miR-26a, miR-34a and miR-146a suppress HCC cell progression by targeting fucosyltransferase 8 (FUT8), the only enzyme responsible for β1,6-fucosylation of N-glycans[14]; O-GlcNAc transferase (OGT) was identified as a novel target of miRNA-7 in a mouse glioblastoma xenograft model[15] and of miR-24-1 in human breast cancer cells[16]; mature miR-17-5p and passenger miR-17-3p induce HCC by targeting N-acetylgalactosaminyltransferase 7 (GALNT7)[17]; Let-7c inhibits metastatic ability of mouse hepatocarcinoma cells via targeting mannoside acetylglucosaminyltransferase 4 isoenzyme A (Mgat4a)[11]. The role of miRNAs in regulating glycosylation and tumor metastasis remains mostly unexplored

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Conclusion