Epigenetic modification augments the immunogenicity of human leukocyte antigen G serving as a tumor antigen for T cell-based immunotherapy.

Epigenetic modification augments the immunogenicity of human leukocyte antigen G serving as a tumor antigen for T cell-based immunotherapy.

Oncoimmunology. 2016 Jun;5(6):e1169356

Authors: Ishibashi K, Kumai T, Ohkuri T, Kosaka A, Nagato T, Hirata Y, Ohara K, Oikawa K, Aoki N, Akiyama N, Sado M, Kitada M, Harabuchi Y, Celis E, Kobayashi H

Abstract
Tumor immune escape has been a major problem for developing effective immunotherapy. The human leukocyte antigen G (HLA-G) is a non-classical MHC class I molecule whose primary function is to protect the fetus from the mother's immune system. While HLA-G is hardly found in normal adult tissues, various tumor cells are known to express it, aiding their escape from the immune system. Thus, HLA-G is an attractive immunotherapy target. CD4(+) helper T lymphocytes (HTLs) play an important role in the immune reaction against tumors by assisting in the generation and persistence of CD8(+) cytotoxic T lymphocytes (CTLs) or by displaying direct antitumor effects. We report here that HLA-G expression in breast cancer significantly correlates with a poor prognosis. Also, we describe that the MHC class II-binding peptide HLA-G26-40 was effective in eliciting tumor-reactive CD4(+) T cell responses. Furthermore, treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine increased HLA-G expression in tumors and subsequently enhanced recognition by HLA-G26-40-specific HTLs. These findings predict that a combination immunotherapy targeting HLA-G together with a DNA methyltransferase inhibitor could be useful against some cancers.

PMID: 27471649 [PubMed]

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