The Positive Relationship Between γH2AX and PD-L1 Expression in Lung Squamous Cell Carcinoma

BACKGROUND/AIM: Lung squamous cell carcinoma often arises from precancerous lesions where alterations in tumor suppressor genes and subsequent chromosomal instability are often observed due to carcinogen exposure. These tumors are often immunogenic; as such, immune checkpoint inhibitors are a promising therapeutic option. We hypothesized that the DNA damage response in tumor cells induces an immune response, thereby up-regulating programmed death-ligand 1 (PD-L1) expression on tumor cells, which in turn sensitizes them to anti-PD-1 therapy. PATIENTS AND METHODS: An immunohistochemical analysis was performed in 41 consecutive lung squamous cell carcinoma patients who underwent surgery at our institution between April 2013 and March 2014. RESULTS: The analysis revealed a high PD-L1 expression in 15 patients (37%) (p=0.028). The PD-L1 expression was positively associated with the nuclear γH2AX expression (p=0.02), that was confirmed by immunofluorescent staining. CONCLUSION: Our findings demonstrate that nuclear γH2AX expression is positively associated with the PD-L1 expression in lung squamous cell carcinoma.