MiR-146b-5p regulates the scavenging effect of GPx-3 on peroxide in papillary thyroid cancer cells

Dan Zhang; Ji-Jun Deng; Qin Xu; Yang Zeng; Jun Jiang

doi:10.1016/j.heliyon.2023.e18489

MiR-146b-5p regulates the scavenging effect of GPx-3 on peroxide in papillary thyroid cancer cells

Heliyon. 2023 Jul 20;9(8):e18489. doi: 10.1016/j.heliyon.2023.e18489. eCollection 2023 Aug.

Authors

Dan Zhang^{1

2}, Ji-Jun Deng¹, Qin Xu¹, Yang Zeng³, Jun Jiang¹

Affiliations

¹ Department of General Surgery (Thyroid Surgery), The Affiliated Hospital of Southwest Medical University, PR China.
² Department of Thyroid and Breast Surgery, The Third People's Hospital of Yibin, PR China.
³ Department of Orthodontics, The Affiliated Stomatological Hospital of Southwest Medical University, PR China.

Abstract

Background: Glutathione peroxidase (GPx) is an important antioxidant enzyme in thyroid follicular cells. Reduced levels of glutathione peroxidase 3 (GPx-3) expression in papillary thyroid cancer (PTC) are associated with poor prognosis. However, the reason for the decreased expression level of GPx-3 in PTC is unclear.

Methods: The expression of GPx-3 in papillary thyroid carcinoma and adjacent normal tissue (n = 18) was detected by Western blotting. Bioinformatics was used to predict the relationship between the level of GPx-3 and gender, age, lymph node metastasis, stage, BRAF^V600E mutation, and recurrence-free survival of patients. The possible upstream microRNAs of GPx-3 were analyzed by bioinformatics tools also. We verified the relationship between GPx-3 and upstream microRNA by dual luciferase reporter assay and enzyme-linked immunosorbent assay (ELISA).

Results: The protein level of GPx-3 decreased in PTC, and analysis of public database datasets suggests that its decreased expression may be associated with the BRAF^V600E mutation. MiR-146b-5p was significantly overexpressed in PTC. The dual luciferase reporter assay verified the effect of miR-146b-5p on 3'-UTR of GPx-3 mRNA. Knockdown of miR-146b-5p in thyroid cancer cell lines TPC-1 and BCPAP increased GPx-3 expression levels, accompanied by an increase in the conversion of glutathione (GSH) to oxidized glutathione (GSSG).

Conclusions: In conclusion, the level of GPx-3 decreases in papillary thyroid carcinoma and impairs intracellular peroxide clearance, due to the inhibitory effect of miR-146b-5p. The accumulation of intracellular peroxides may contribute to the poor prognosis of thyroid cancer.

Keywords: Glutathione peroxidase 3 (GPx-3); Oxidative stress (OS); Papillary thyroid carcinoma (PTC); miR-146b-5p.