[Analysis of <i>PIKFYVE</i> gene expression, clinical significance, and experimental validation based on TCGA database in hepatocellular carcinoma].

<b>Objective:</b> To experimentally validate clinical samples, analyze the mRNA expression of the FYVE domain containing phosphatidylinositol 3-phosphate 5 kinase (<i>PIKFYVE</i>) gene, and its clinical significance based on the Cancer Genome Atlas (TCGA) database in hepatocellular carcinoma (HCC). <b>Methods:</b> Data information on 424 clinical samples (including 374 cases of HCC tissues and 50 cases of non-tumorous liver tissues) were collected based on the TCGA database. Cox regression analysis and the Kaplan-Meier method were used to analyze the relationship between mRNA expression of the <i>PIKFYVE</i> gene and the clinical characteristics as well as survival prognosis in patients with HCC. The relationship between the <i>PIKFYVE</i> gene and immune cell infiltration was examined by correlation analysis with 24 kinds of immune cells. In addition, the mRNA expression level of the <i>PIKFYVE</i> gene and RAC-alpha serine/threonine-protein kinase (<i>AKT1</i>), phosphatase and tensin homolog (<i>PTEN</i>), protein kinase C alpha (<i>PRKCA</i>), inositol polyphosphate-5-phosphatase (<i>INPP5D</i>), phosphoinositide-3-kinase regulatory subunit 1 (<i>PIK3R1</i>), inositol polyphosphate 4-phosphatase type II (<i>INPP4B</i>) and phospholipase C beta 4 (<i>PLCB4</i>) gene correlations were analyzed in HCC tissues. At the same time, paraffin sections of highly differentiated, moderately differentiated, poorly differentiated, and non-tumor liver tissues from patients with HCC were collected from the Department of Pathology of the First Affiliated Hospital of Xinjiang Medical University. The histopathological observation was performed by HE staining. Immunohistochemistry was used to verify the expression levels of the PIKFYVE and Ki67 proteins in each clinical sample. The t-test was used for intergroup comparison of continuous data. The <i>χ</i>² test and Wilcoxon rank sum test were used for intergroup comparison of enumeration data. The Kaplan-Meier method was used for survival analysis. <b>Results:</b> The expression level of the <i>PIKFYVE</i> gene was higher in the HCC tumor than that in normal liver tissue (<i>P</i><0.01). The overall survival time of patients was significantly longer in the low expression group than that in the high expression group (<i>HR</i>=1.57, 95%<i>CI</i>: 1.10～2.25, <i>P</i>=0.014). The results of univariate Cox regression analysis showed that tumor stage, pathological grade, tumor status, residual tumor, and <i>PIKFYVE</i> expression level all had an effect on OS (<i>P</i><0.05). The PIKFYVE prognostic risk model had a proportionate score of <i>HR</i>=1.533 (95%<i>CI</i>: 1.077～2.181, <i>P</i>=0.018). Multivariate Cox risk regression analysis showed that the PIKFYVE prognostic risk model had a proportionate score of <i>HR</i>=1.481 (95%<i>CI</i>: 0.886～2.476, <i>P</i>=0.134) and an area under the receiver operating characteristic curve of 0.559, indicating that it had predictive value for survival prediction. The results of the correlation analysis showed that the expression level of <i>PIKFYVE</i> was strongly correlated with immune cell infiltration and TP53 (<i>P</i><0.01). The results of immunohistochemical staining showed that the expression level of PIKFYVE was significantly higher in HCC tissue samples than that in non-tumor liver tissues (<i>P</i><0.01), and was negatively correlated with the degree of differentiation. <b>Conclusion:</b> PIKFYVE, as an independent risk factor, is expected to be developed into a biomarker for clinical diagnosis, offering a reference for novel therapeutic agents in HCC.