TFAP2A is a novel regulator that modulates ferroptosis in gallbladder carcinoma cells via the Nrf2 signalling axis

H.-X. Huang, G. Yang, Y. Yang, J. Yan, X.-Y. Tang, Q. Pan

Department of Critical Care Medicine, Children’s Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing, P.R. China. qi_pan@vip.sina.com

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• Oncology

OBJECTIVE: Ferroptosis is a recently identified form of controlled cell death generally associated with the accumulation of lipid-associated reactive oxygen species (ROS). However, the molecular mechanisms underlying ferroptosis have not been established.

MATERIALS AND METHODS: Microarray expression data for three human gallbladder carcinoma (GBC) and matched non-tumour specimens were downloaded from the Gene Expression Omnibus (GEO) repository. Candidate genes were filtered using bioinformatic analysis. After cell transfection, candidate gene impacts on cell proliferation, migration, invasion and ferroptosis (ferrous iron (Fe2+) and malondialdehyde (MDA) levels) were assessed.

RESULTS: We screened 626 differentially expressed genes (DEGs) including 465 that were downregulated and 161 that were upregulated in the three tissue pairs. These DEGs were used to construct a protein-protein interaction (PPI) network. Functional enrichment analysis revealed the top three modules in the network and four hub genes. Transcription factor AP-2 alpha (TFAP2A) was screened and showed overexpression in The Cancer Genome Atlas (TCGA) digestive system tumour data and a relationship with clinical survival. In vitro, GBC exhibited upregulated expression of TFAP2A, whose inhibition reduced GBC cell proliferation, migration, and invasion. Fe2+ and MDA levels were elevated. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed TFAP2A enrichment in oxidative stress. Subsequent experiments demonstrated that TFAP2A silencing attenuated the expression of key genes associated with oxidative stress such as heme oxygenase 1 (HO-1), nuclear factor erythroid 2 like 2 (Nrf2), ferritin heavy chain 1 (FTH1) and NAD(P)H quinone dehydrogenase 1 (NQO1).

CONCLUSIONS: Bioinformatic and experimental analyses reveal that TFAP2A plays a vital role in ferroptosis and hence is a potential therapeutic target for GBC treatment.

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