Association Between PD-L1 and Histatin1, 3 Expression in Advanced Head and Neck Squamous Cell Carcinoma

Background/aim: The prognosis of advanced stage head and neck squamous cell carcinoma (HNSCC) has remained unimproved for the past decades. Therefore, novel diagnostic markers and treatment options are required. Recently, an inhibitor for immune checkpoint program death ligand-1 (PD-L1), was approved by the FDA, and used in HNSCC patients. Histatins (HTNs), one of the common antimicrobial peptides in saliva, have demonstrated wound healing and antifungal capabilities and other functions on the oral epithelium. Dysregulation of HTN1 and HTN3 has also been reported in HNSCC through genomic and proteomic studies. This study aimed to investigate the association between histatins (HTN1 and HTN3) and PD-L1 in advanced HNSCC.

Patients and methods: Data of gene expression in HNSCC were collected from TCGA and analyzed using a data-mining platform website (https://ualcan.path.uab.edu/). Tissue microarrays containing 98 samples of HNSCC patients and non-neoplastic controls were immunolabeled against PD-L1, HTN1, and HTN3. The immunohistochemistry results were quantified using ImageJ.

Results: The expression of PD-L1 and HTN1 was significantly higher in tumors than normal tissues (p<0.001), but no significant difference was found regarding HTN3. Metastatic HNSCC samples exhibited significantly higher expression of PD-L1 (p<0.018), compared to the non-metastatic group. Association between HTN1 and HTN3 was found using Pearson correlation coefficient (r=0.603, p<0.001). No overall survival difference was evident among our samples.

Conclusion: PD-L1 and HTN1 are associated with the progression of HNSCC. PD-L1 expression correlated with that of HTN3.