High expression of STAT3 and PD-L1 predicts poor prognosis for laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) ranks among the most prevalent malignant tumors in the head and neck region. Signal transducer and activator of transcription 3 (STAT3) belongs to the family of cytoplasmic latent transcription factors, which has been discovered to be activated in various human cancers and is linked to cancer progression, lymph node metastasis, and unfavorable prognosis. Programmed cell death 1/ programmed cell death ligand 1 (PD-1/PD-L1) has a significant role in the immunosuppressive processes of numerous cancers. However, the specific roles of STAT3 and PD-L1 in LSCC remain unclear. Single sample GSEA was used to explore the link between STAT3 and immune cell infiltration. The Cancer Genome Atlas (TCGA) database revealed the expression levels of STAT3 and PD-L1 and their correlation on mRNA level in patients with LSCC. The expression of STAT3 and PD-L1 proteins was analyzed using immunohistochemistry (IHC). STAT3 and PD-L1 expression were significantly elevated in LSCC tumors. The overall survival rates were notably higher for LSCC patients with low levels of STAT3 and PD-L1 expression than for those with high levels (both P < 0.05). Increased levels of the STAT3, PD-L1 and in combination were positively linked to the pathological differentiation and lymph node metastasis status in patients with LSCC(all P < 0.05). Compared to normal tissue, LSCC exhibited significantly elevated mRNA levels of STAT3 and PD-L1, with both STAT3 and PD-L1 demonstrating a notable increase in expression in LSCC samples at the mRNA and protein levels compared to non-cancerous tissue. Increased STAT3 and PD-L1 may function as promising biomarkers indicating poor prognosis in patients who have undergone surgical resection for LSCC.