HLA-G in Testicular Germ Cell Tumors

Background: HLA-G is a non-classical major histocompatibility complex class I molecule. HLA-G expression has been found in various types of solid and hematological malignancies. It is also expressed in normal testicular and epididymal tissue. However, expression of HLA-G in testicular germ cell tumors has not been extensively studied. The aim of this study was to investigate whether HLA-G protein is present in different components of testicular germ cell tumors.

Patients And Methods: 34 testicular cancer patients, for whom tumor tissue was available, were included in the study. Immunohistochemical staining was performed on tissue sections from formalin-fixed, paraffin-embedded tissue samples.

Results: 7 (20.6%) patients had positive HLA-G staining in at least 1 component of the tumor sample. In 3 of 7 patients with intratubular germ cell neoplasia, staining with HLA-G was seen in this component. All of the choriocarcinoma components were strongly positive, and about 40% of teratoma components had immunopositivity. The components of seminoma and embryonal carcinoma, and most yolk sac tumors were negative. HLA-G immuno-positivity was not associated with tumor size, retroperitoneal lymph node involvement, distant metastasis, or relapse/refractory status.

Conclusion: This study demonstrated that testicular choriocarcinoma and some teratomas express HLA-G, but not seminoma, embryonal carcinoma, and yolk sac tumors.