HLA-G Expression is Associated with an Unfavorable Prognosis of Oral Squamous Cell Carcinoma

Background: HLA-G, a major histocompatibility complex of non-classical class Ib, plays a key role in the development of the primary tumors to metastatic stages. The aim of this study was to investigate HLA-G expression in oral squamous cell carcinomas and its relationship with clinicopathological factors. Methods: After immunohistochemical staining for HLA-G with 63 formalin fixed and paraffin embedded blocks (33 oral squamous cell carcinoma and 30 normal oral mucosa samples), staining intensity, percentage of stained cells and final immunoreactivity score were evaluated, along with other variables. Results: Staining intensity, percentage of stained cells and final immunoreactivity scores in oral squamous cell carcinomas were higher than those in normal oral mucosa (all P=0.001). The staining intensity in the parenchyma of squamous cell carcinoma cells was significantly associated with the clinical tumor stage (P=0.022) and the group with lymphatic metastasis exhibited a higher staining percentage (P=0.026). Staining intensity and immunoreactivity score (IRS) exhibited a significant but inverse correlation with survival rate (P=0.004 and P=0.018, respectively) and a significant direct relationship with clinical stage (P=0.001 and P=0.001). Conclusion: The results supported a role of HLA-G in development of oral squamous cell carcinomas and metastasis to lymph nodes. It might be useful in molecular-targeted therapy.