Soluble Human Leukocyte Antigen-G Expression in Patients with Ductal and Lobular Breast Malignancy

Background: Human leukocyte antigen-G (HLA-G) has been closely associated with diagnosis and prognosis in many types of human cancer. The current study aims to investigate soluble (s) HLA-G expression in patients with breast malignancy. Patients and Methods: sHLA-G plasma expression was determined in 120 patients with breast cancer and 40 healthy controls using enzyme-linked immunosorbent assay. Results: Plasma sHLA-G levels were significantly higher in breast cancer patients compared to healthy controls (p<0.001), with an area under the receiver operating characteristic (ROC) curve of 0.735 (95% Confidence interval=0.630-0.841, p<0.001). Significantly increased sHLA-G expression was detected in patients with mixed type of coexisting ductal and lobular breast lesions, compared to patients with pure ductal carcinoma or pure lobular neoplasia (p<0.05). Conclusion: sHLA-G expression is closely associated with the histological type of breast cancer. Our findings support the application of sHLA-G as a potential biomarker in body fluids for preoperative breast cancer detection and diagnosis. Human leukocyte antigen-G (HLA-G) belongs to the non- classical HLA class I family of genes and was originally described to be selectively expressed at the maternal−fetal interface on cytotrophoblast cells, thereby contributing to maternal−fetal tolerance (1). Alternative splicing of the primary transcript generates seven different isoforms of the molecule, four of which are membrane-bound (HLA-G1, -G2, -G3 and - G4) while the other three are soluble (HLA-G5, -G6 and -G7) (2, 3). One additional soluble form of the molecule may be generated by shedding of the proteolytically cleaved surface