Bioinformatics Analysis Confirms FLAD1 as a Prognostic and Immune Biomarker in Hepatocellular Carcinoma

Objective: To investigate the functional role and molecular mechanisms of flavin adenine dinucleotide synthetase 1 (FLAD1) in the initiation and progression of hepatocellular carcinoma (HCC).Methods: The gene expression and clinical data of HCC patients were obtained from TCGA and GEO, and the expression of FLAD1 was analyzed using TIMER2 and HPA.Differential analysis was performed using DESeq2 and limma packages, and feature genes were screened by single-factor COX survival analysis and three machine learning algorithms.Genes related to immune regulation were screened by WGCNA and PPI analysis, and co-expression analysis was performed with FLAD1.Drug sensitivity analysis combined with molecular docking revealed the relationship between FLAD1 and commonly used cancer drugs.The impact of FLAD1 on the biological functions of liver cancer cells was evaluated through colony formation assays, Transwell migration and invasion assays, as well as subcutaneous tumor xenograft experiments in mice.Results: The expression of FLAD1 in liver cancer tissues was significantly higher than that in normal tissues, and was associated with poor prognosis.Immunoinfiltration analysis showed that the immunomicroenvironment score of the group with high expression of FLAD1 was significantly lower than that of the group with low expression, suggesting that FLAD1 might inhibit immune response.WGCNA and PPI analysis identified genes closely related to immune infiltration and co-expression with FLAD1.The FLAD1 gene promotes the proliferation, invasion, and migration of liver cancer cells.Conclusion: FLAD1 can be used as a biomarker for poor prognosis of hepatocellular carcinoma, and its mechanism may be related to remodeling immunosuppressive microenvironment, and provide a potential strategy for combined target therapy.