Potential role of P4HB in the tumor microenvironment and its clinical prognostic value: a comprehensive pan-cancer analysis and experimental validation with a focus on KIRC.

Background: Tumor microenvironment (TME) plays a crucial role in tumor growth and metastasis. Exploring biomarkers that are significantly associated with TME can help guide individualized treatment of patients.

Methods: We analyzed the expression and survival of P4HB in pan-cancer through the TCGA database, and verified the protein level of P4HB by the HPA database. In addition, we used the Metascape database to construct protein-protein interaction networks and the single-cell Sequencing database for functional analysis. An immune cell infiltration analysis was performed to explore the potential role of P4HB in TME. We further analyze the relationship between P4HB and immune checkpoint molecules to explore the role of P4HB in immune checkpoint blockade therapy. Finally, the oncogenic role of P4HB in RCC cells was validated using colony formation and wound healing assays.

Results: RNA and protein levels of P4HB were extensively up-regulated in pan-cancer. However, high P4HB expression was associated with poor survival in KIRC. The clinical relevance analyses of P4HB suggested that high P4HB expression was associated with advanced clinical TNM stage. Moreover, multivariate cox regression analysis indicated that P4HB (HR = 1.372, 95% CI 1.047-1.681, P = 0.019) was an independent risk factor for OS in KIRC. Functional analysis revealed that P4HB is involved in hypoxia, TME and immune system processes. Our study also found that high P4HB expression was significantly correlated with elevated infiltration levels in CD8 + T cells and M2 macrophages. The results of colony formation and wound healing assays showed that knockdown of P4HB inhibited the RCC growth and migration.

Conclusions: P4HB is a specific biomarker for KIRC prognosis and is significantly associated with clinical characteristics. In addition, P4HB may play an influential role in TME and is a biomarker for ICB therapy.