ABSTRACT
Objective:To screen and verify the key radioresistance genes regulated by m6A methylation in nasopharyngeal carcinoma (NPC) based on the chip data and cell experiments.Methods:The microarray data of NPC radioresistance genes, m6A regulated genes and mRNA expression profiles of NPC genes were downloaded from Gene Expression Omnibus (GEO) database. The differential genes were screened and statistically analyzed by R software. The biological processes, signal pathways and interaction networks of these genes were analyzed by bioinformatics. The m6A regulatory factors were knocked down and the radioresistant strains were constructed. The above m6A differential radioresistant genes of NPC were screened and verified by real-time reverse transcription PCR (qRT-PCR) and Western blot. The m6A modification of screened genes and their direct binding ability with methyltransferase 3 (METTL3) were verified by methylated RNA immunoprecipitation qPCR (MeRIP-qPCR). The siRNA of selected genes was transfected into NPC cells, and after treatment with ionizing radiation, cell proliferation was detected by CCK-8 assay and EdU, apoptosis and cell cycle were detected by flow cytometry, and radiosensitivity was detected by clone formation assay. The trend of differences in the abundance of Fe 2+ and lipid peroxidation between the control and EGLN3 knockdown groups after ionizing radiation treatment was compared by paired t-test. Results:Chip data GSE48501 intersected with GSE200792 and GSE53819 to obtain 6 differential genes, including EGLN3, FOSL2, ADM, JUN, VEGFA and PRDM1. The target genes of EGLN3 and FOSL2 were further screened by TNMplot and KMplot, etc. The mRNA of the target genes directly bound to METTL3 and were subjected to its mediated modification of m6A. The target genes were up-regulated in the parental cells after irradiation in a dose and time gradient manner, which were also significantly up-regulated in radioresistant cells. After EGLN3 and FOSL2 were down regulated, the proliferation activity of NPC cells was more significantly decreased after irradiation, and the radiosensitization ratio was statistically significant compared with that of NPC cells without EGLN3 and FOSL2 down-regulation. After irradiation, EGLN3 down-regulated NPC cells significantly down-regulated glutathione peroxidase 4 (GPX4) expression, increased the abundance of Fe 2+ and lipid peroxidation, which played a role in radiosensitization by inducing ferroptosis. Conclusions:EGLN3 and FOSL2 play a role in radioresistance in NPC through METTL3 mediated m6A methylation. Down-regulation of EGLN3 combined with ionizing radiation can increase the intracellular Fe 2+ abundance and lipid peroxidation and down-reuglate the expression of GPX4 in NPC cells, which can enhance radiosensitization for NPC radiotherapy by the ferroptosis pathway.
ABSTRACT
Ferroptosis is a new form of regulated cell death discovered in recent years, which is iron-dependent cell death characterized by peroxidation of polyunsaturated fatty acid phospholipids. Recent studies have shown that radiotherapy can induce ferroptosis in cancer cells via ionizing radiation. Targeting ferroptosis plays a synergistic role in tumor suppression with radiation, which not only further deepens the connotation of radiobiology, but also provides a new perspective for tumor radiosensitization. This review systematically summarizes the occurrence and defense of ferroptosis, focusing on the key role of ferroptosis in the radiobiological effects of tumor cells and the potential application of ferroptosis in radiosensitization.