Human leukocyte antigen-G (HLA-G) expression plays an important role in the diagnosis and grading of endometrial cancer.

The research aimed to investigate the expression of human leukocyte antigen G (HLA-G) in cancer tissues and normal endometrium and the expression of HLA-G in the three different grades of Endometrial cancer, to determine if HLA-G expression is related with the diagnosis and grading of endometrial cancer. The expression of HLA-G protein was analysed in the primary tumour in 97 tissue samples obtained from endometrial cancer, in which 30 samples were at pathological Grade 1; 37 samples were at Grade 2; 27 samples were at Grade 3; and the other 5 samples were obtained from normal endometrium. The HLA-G protein level was measured by immunohistochemical method and analysed according to the clinicopathological parameters of patients. A statistically significant difference ( < .05) was observed in HLA-G expression between the cancerous tissue and the normal endometrium ( = .0007), and the histochemistry score (H-score) of the negative control was 0.05 ± 0.03 (mean ± SD). Statistically significant correlations were also observed between samples of pathological Grade 1 and Grade 2 ( = .0126), Grade 2 and Grade 3 ( = .0359), Grade 1 and Grade 3 ( = .0001). Endometrial cancer cells express higher levels of HLA-G probably to escape immune surveillance, and HLA-G expression level is related with the pathological grade of endometrial cancer. Therefore, HLA-G detecting and quantifying could possibly help diagnosing, grading and treatment of endometrial cancer.Impact statement The expression of a member of the non-classical HLA antigens, HLA-G, is one of the main ways for tumour immune escape and progression. The significance of HLA-G in tumour biology has been intensively investigated (Carosella et al. 2015), and now it is widely acknowledged that HLA-G expression in tumours is highly linked with immune suppressive microenvironments, advanced tumour stage, poor therapeutic responses and prognosis (Lin and Yan, 2018). However, to our knowledge, no research has been conducted on the correlation between HLA-G expression and pathological grades of endometrial cancer. Our study demonstrated that the expression of HLA-G plays an important role in the pathological grading of endometrial cancer. Measuring the level of HLA-G expression to help pathological grading of endometrial cancer is important in determining the treatment of patients with endometrial cancer and studying the underlying mechanisms of the development of endometrial cancer, while proving or finding new targeted therapies inhibiting or modifying these processes still requires further investigation.