Integrated Analysis and Validation Reveal CYTH4 as a Potential Prognostic Biomarker in Acute Myeloid Leukemia

Abstract

Abstract Background Acute myeloid leukemia (AML) is a clonal hematological malignancy with high mortality rates, and the clinical and genomic heterogeneity of AML has complicated therapy development. Identifying novel markers is urgently in need for AML. Cytohesins are a subfamily of guanine nucleotide exchange factors (GEFs) activating ADP-ribosylation factor (ARF) family GTPases. While previous studies have reported the important roles of cytohesins in various cancers, their function in AML remains unclear. Therefore, we performed this study to explore the prognostic impact of cytohesin-4 (CYTH4) and investigate the underlying molecular functions. Methods We obtained RNA sequencing data and AML clinical data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets to investigate gene expression and survival. Using R software, we identified differentially expressed genes between the high-CYTH4 group and the low-CYTH4 group. We conducted functional enrichment analysis by performing GO, KEGG, and GSEA analyses. CIBERSORTx tool was used to explore the proportions of different immune cell types. We also evaluated the molecular function of CYTH4 by examining cell growth, cell cycle, apoptosis, and colony-forming ability using CYTH4-knockdown AML cell lines. Results CYTH4 was significantly overexpressed in AML when compared with other cancers and normal tissues. High CYTH4 expression was associated with old age (p = 0.014), complex karyotype (p = 0.048), and higher risk status (p = 0.001). Patients with high CYTH4 expression had poor overall survival (OS) (high vs. low, HR = 1.58, 95%CI 1.04–2.45, p = 0.032) and event-free survival (EFS) (high vs. low, HR = 1.84, 95%CI 1.13–2.94, p = 0.013), and these patients could benefit from transplantation (transplantation vs. chemotherapy, HR = 0.35, 95%CI 0.20–0.60, p = 0.0001). Multivariate analysis showed high CYTH4 expression was independently associated with inferior OS (HR = 1.01, 95%CI 1.00-1.03, p = 0.017) and EFS (HR = 1.02, 95%CI 1.00-1.03, p = 0.034). Functional analysis showed that CYTH4 was involved in immunoregulation. In vitro validation showed knockdown of CYTH4 adversely affected cell growth and induced cell apoptosis. Conclusions CYTH4 is highly expressed in AML and can potentially function as a prognostic biomarker.