Abstract
Background/AimsFolic acid (FA) is a core micronutrient involved in DNA synthesis/methylation, and the metabolism of FA is responsible for genomic stability. MicroRNAs may affect gene expression during folate metabolism when cellular homeostasis is changed. This study aimed to reveal the relationship between FA deficiency and the expression of miR-22-p/miR-149-5p and the targeted regulation of miR-22-3p/miR-149-5p on the key folate metabolic gene Methylenetetrahydrofolate reductase (MTHFR).MethodsNormal (HL-7702 cells) and cancerous (QGY-7703 cells) human hepatocytes were intervened in modified RPMI 1640 with FA deficiency for 21 days. The interaction between MTHFR and the tested miRNAs was verified by Dual-Luciferase Reporter Assays. The changes in the expression of miR-22-3p/miR-149-5p in response to FA deficiency were detected by Poly (A) Tailing RT-qPCR, and the expression of MTHFR at both the transcriptional and translational levels was determined by RT-qPCR and Western blotting, respectively.ResultMiR-22-3p/miR-149-5p directly targeted the 3’UTR sequence of the MTHFR gene. FA deficiency led to an upregulation of miR-22-3p/miR-149-5p expression in QGY-7703/HL-7702 cells, while the transcription of MTHFR was decreased in QGY-7703 cells but elevated in HL-7702 cells. Western blotting showed that FA deficiency resulted in a decline of the MTHFR protein in QGY-7703 cells, whereas in HL-7702 cells, the MTHFR protein level remained constant.ConclusionThe results suggested that miR-22-3p/miR-149-5p exert different post-transcriptional effects on MTHFR under conditions of FA deficiency in normal and cancerous human hepatocytes. The results also implied that miR-22-3p/miR-149-5p might exert anticancer effects in cases of long-term FA deficiency.
Highlights
MicroRNAs are small endogenous noncoding RNAs (19–24 nucleotides in length) that have emerged as key negative regulators that target gene expression at the post-transcriptional level [1, 2]
The results suggested that miR-22-3p/miR-149-5p exert different post-transcriptional effects on Methylenetetrahydrofolate reductase (MTHFR) under conditions of Folic acid (FA) deficiency in normal and cancerous human hepatocytes
To identify the roles of miR-22-3p and miR-149-5p in the development of hepatocellular carcinoma (HCC) under conditions of FA deficiency, we analyzed the expression level of miR-22-3p by Poly(A) Tailing quantitative real-time PCR (RT-qPCR) in the HCC cell line QGY-7703 on the 14th and 21st day after the start of FA deficiency; a matched normal hepatocyte cell line (HL-7702) was examined
Summary
MicroRNAs (miRNAs) are small endogenous noncoding RNAs (19–24 nucleotides in length) that have emerged as key negative regulators that target gene expression at the post-transcriptional level [1, 2]. MicroRNAs have multiple targets, and several miRNAs can meticulously regulate the same gene simultaneously. MiRNAs contribute to various aspects of animal development and/or human disease[4]. The dysregulation of miRNAs is responsible for one-carbon metabolism (OCM, or folate metabolism), which results in an imbalance of DNA synthesis, methylation, amino acid metabolism and cellular replication. Imbalances in these events are frequently related to an increased risk of various diseases, such as hepatocellular carcinoma (HCC), as some miRNAs act as oncogenes, which leads to the dysregulation of their target gene products in tumors[5, 6]
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