Abstract 5327: Upregulation of the expression of nonclassical MHC class I HLA-G antigen in human breast cancer cell lines and tissue

Abstract

Abstract HLA-G is a nonclassical MHC class I molecule with immunotolerant properties. HLA-G is normally expressed by trophoblastic cells during pregnancy and protects the fetus from the maternal immune system. HLA-G is also overexpressed in tumors and plays a role in immune evasion of cancer. In this study, we used RT-PCR and immunohistochemistry (IHC) to examine HLA-G expression in normal mammary epithelial and breast cancer cell lines, normal breast tissue, and human breast cancer tissue. RT-PCR showed that normal epithelial MCF-12A cells had no HLA-G mRNA expression, while the breast cancer cell lines MCF-7, T47D and MDA-MB-231, and drug-resistant cell line NCI/Adr-Res had various levels of HLA-G mRNA expression. Furthermore, three mRNA isoforms were expressed in breast cancer cell lines. Twelve normal breast tissues from plastic surgery and 38 breast cancer tissues from mastectomy were examined by IHC. While 60.5% (23 of 38 samples) of breast cancers had medium to strong staining to HLA-G, only 33% (4 of 12 samples) of normal breast tissues had weak staining, the difference was significant (p<0.05). HLA-G staining was diffusely distributed in the membrane and cytoplasm of the cancer cells and mammary epithelia. Rare staining was found in fibroblasts, vascular endothelia or inflammatory cells. In conclusion, breast cancer cells over-express HLA-G mRNA and protein in cell lines and tumors. The role of HLA-G over-expression in breast cancer-related immune evasion remains to be determined. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5327.