Expression and immune infiltration studies of IL-33-ST2-NF-κB signaling pathway in prostate cancer.

Background: To analyze the expression of interleukin-33 (IL-33), growth-stimulated expression gene 2 (ST2), nuclear factor-kappaB (NF-κB) and immune cell infiltration in prostate cancer, this study aims to provide an experimental basis for the clinical prevention and treatment of prostate cancer.

Methods: The expression of IL-33 in PCa tissues was analyzed using TCGA, TIMER and HPA databases. Using the UALCAN database, the systematic exploration of the relationship between IL-33 and various clinicopathological parameters was conducted. The correlation between IL-33 expression and immune cell infiltration was investigated using TIMER, CIBERSORT and GEPIA databases. To verify these analyses, 22 cases of normal prostate (NP), 76 cases of benign prostatic hyperplasia (BPH), and 100 cases of PCa were recruited. Immunohistochemical staining was performed to examine the expression of IL-33, ST2, NF-κB, and the infiltration of immune cells. Correlations between these factors were then determined.

Results: The expression of IL-33, ST2 and NF-κB was significantly lower in PCa tissues compared with NP (p < 0.05). IL-33 was not associated with age in PCa but showed associations with race, molecular characteristics, lymph node metastatic status, TP53 mutation and tumor grade. Furthermore, IL-33 was associated with immune cell infiltration. Positive correlations were observed between IL-33 and ST2 expressions, as well as between IL-33 and CD68⁺ macrophages in BPH and PCa.

Conclusions: IL-33, ST2 and NF-κB are lowly expressed in PCa tissues, their expression decreases with the increasing malignancy of cancer. IL-33, ST2 and NF-κB are factors associated with PCa immune infiltration. IL-33 has an inhibitory effect on prostate cancer through the IL-33/ST2/NF-κB signalling pathway.