Head and neck squamous cell carcinoma (
HNSCC) ranks among the top most common
cancers with a poor prognosis. The mechanism of chemoresistance is still not well known. This study is to investigate the
programmed death-ligand 1 (PD-L1) expression in
HNSCC, and test the effect of
lactoferricin B (LfcinB) on chemoresistance and its mechanism. We analyzed 510
HNSCC patients in TCGA database and investigated how CD274 expression was related to patient prognosis. PD-L1 was verified from
HNSCC samples at local hospital with immunohistochemistry. PD-L1 expression in the acquired
cisplatin-resistant
HNSCC cells was examined by PCR and WB in order to test PD-L1-induced chemoresistance. LfcinB inoculation in
cisplatin-resistant
HNSCC cells and in the nude mice was introduced to test the effect of LfcinB on targeting
cisplatin resistance and its mechanism. High CD274
mRNA (>125 FPKM) from TCGA database had a significantly reduced 5-year survival rate, and a lower 5-year survival rate in the
chemotherapy and
radiotherapy-treated patients (P < .05). PD-L1 overexpression was further supported from analysis of 40
HNSCC specimens. PD-L1 and
IL-6 in the established
cisplatin-resistant
HNSCC cells were shown significantly higher (P < .05).
IL-6 and PD-L1 expression were partially inhibited by the anti-IL-6/STAT3 antibody. LfcinB displayed a direct cytotoxic effect on
cisplatin-resistant
HNSCC cells and
HNSCC xenografts of
cisplatin-resistant cells in the nude mice displayed significant reduction in
tumor volume after LfcinB injection (P < .05). Besides, the increase of
IL-6 and PD-L1 in
cisplatin-resistant
HNSCC cells was abolished in vitro by LfcinB (P < .05). PD-L1 expression in
HNSCC cells correlates with poor prognosis and chemoresistance, and LfcinB might provide therapeutic potential in
HNSCC patients through modulating
IL-6 and PD-L1.