RHBDF2 Is Correlated With Immune Infiltrates and Shows Prognostic Association in Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) is a heterogeneous disease with a complex immunosuppression microenvironment, necessitating the identification of preferable biomarkers to enhance the efficacy of immunotherapy. Rhomboid 5 homolog2 (RHBDF2), through its interaction with A Disintegrin And Metalloprotease 17 (ADAM17), has been implicated in immune responses and tumor progression; however, its role in AML remains insufficiently investigated. Methods: This investigation delineated the expression profile of RHBDF2 and its correlation with the clinical features of AML using The Cancer Genome Atlas (TCGA, n = 150 AML patients) and Genotype-Tissue Expression (GTEx, n = 337 non-malignant control individuals) databases. The RNA and protein expression levels of RHBDF2 were validated in a single-center clinical cohort (105 bone marrow fluid samples and 125 bone marrow biopsy specimens) via quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). To elucidate the correlation between RHBDF2 and the complex immune regulatory microenvironment of AML, we performed functional enrichment analyses (Gene Ontology [GO] and Kyoto Encyclopedia of Genes and Genomes [KEGG]), Gene Set Variation Analysis (GSVA), immune cell infiltration analysis, and single-cell sequencing t-distributed stochastic neighbor embedding (t-SNE) clustering. Furthermore, we assessed the prognostic value of RHBDF2 using Kaplan-Meier survival analysis, Cox regression, and a prognostic nomogram model. Results: Our findings indicated that RHBDF2 was upregulated in AML compared to non-malignant control samples. Moreover, RHBDF2 expression was associated with immune infiltration and exhibited a positive correlation with several immunological checkpoints including T-cell Immunoglobulin and Mucin-domain containing molecule 3 (TIM3), Programmed Cell Death 1 Ligand 2 (PD-L2), and Herpesvirus Entry Mediator (HVEM), with significant enrichment in the monocytes of AML patients. Multivariate Cox regression analysis revealed that elevated RHBDF2 shows a marginally significant association with overall survival (OS) in AML patients (adjusted Hazard Ratio [HR] = 1.01, 95% Confidence Interval [CI] 1.00–1.02, p = 0.048). Kaplan-Meier analysis showed that high RHBDF2 expression was associated with significantly shorter OS (HR = 1.87, 95% CI 1.22–2.86, p = 0.004). The constructed nomogram model exhibited preliminary prognostic stratification capacity for OS, with time-dependent receiver operating characteristic (ROC) curve analysis yielding area under the curve (AUC) values of 75.2, 80.1, and 95.3 for 1-year, 3-year, and 5-year OS, respectively, with a concordance index (C-index) of 0.76. Conclusion: These correlative findings support that RHBDF2 may be associated with prognosis in AML but requires further validation, offering insights for prognosis prediction and the development of innovative immunotherapy strategies for AML.