Avaliação da expressão da molécula HLA-G no microambiente tumoral e na saliva de pacientes com carcinoma espinocelular de cavidade oral

Abstract

HLA-G is a molecule of the major histocompatibility complex (MHC) class I nonclassical that plays an inhibitory effect on immunocompetent cells that are fundamental in the development of an antitumoral response. In this context, the aim of this study was to evaluate the expression of HLA-G in the microenvironment of oral cavity squamous cell carcinoma (OCSCC) as well as their relationship with clinical and microscopic parameters. In addition, we aimed also to compare the salivary concentration of soluble HLA-G (sHLA-G) in patients with OCSCC with healthy individuals (control group). The techniques of immunohistochemistry and Enzyme- Linked Immunosorbent Assay (ELISA) were used. The results revealed, with the immunohistochemistry technique, that expression of HLA-G by tumor cells was significantly higher in metastatic OCSCC (n=30) (72% of samples) when compared with non-metastatic OCSCC (n=30) (28% of samples) (P=0.01 ). Moreover, patients with a lower expression of HLA-G presented a tendency to survival longer (22 months) when compared with those with a higher expression of the molecule (16 months). With reference to other clinicopathological parameters analyzed, only the presence of lymph node metastasis (P=0.01) and depth of tumor invasion (P=0.02) were significantly associated with the expression of HLA-G. By ELISA technique, we showed that the salivary concentration of soluble HLA-G provided no differentiation between patients with OCSCC from healthy individuals, since there was no statistically significant difference between the analyzed groups (P=0.17). The findings of this study revealed that high expression of HLA-G in the microenvironment of metastatic OCSCC may represent a tumor escape mechanism which contributes to lower survival and an unfavorable clinical prognosis. However, concentration of soluble HLA-G in saliva of patients with OCSCC is similar to healthy individuals; thereby sHLA-G does not represent a salivary biomarker prognostic.