A new transcript in the TCRB locus unveils the human ortholog of the mouse pre-Dß1 promoter.

INTRODUCTION: While most transcripts arising from the human T Cell Receptor locus reflect fully rearranged genes, several germline transcripts have been identified. We describe a new germline transcript arising from the human TCRB locus. METHODS: cDNA sequencing, promoter, and gene expression analyses were used to characterize the new transcript. RESULTS: The new germline transcript encoded by the human TCRB locus consists of a new exon of 103 bp, which we named TRBX1 (X1), spliced with the first exon of gene segments Cß1 or Cß2. X1 is located upstream of gene segment Dß1 and is therefore deleted from a V-DJ rearranged TCRB locus. The X1-Cß transcripts do not appear to code for a protein. We define their transcription start and minimal promoter. These transcripts are found in populations of mature T lymphocytes from blood or tissues and in T cell clones with a monoallelic TCRB rearrangement. In immature thymocytes, they are already detectable in CD1a- CD34+ CD4- CD8- cells, therefore before completion of the TCRB rearrangements. CONCLUSIONS: The X1 promoter appears to be the ortholog of the mouse pre-Dß1 promoter (PDß1). Like PDß1, its activation is regulated by Eß in T cells and might facilitate the TCRB rearrangement process by contributing to the accessibility of the Dß1 locus.

Identification of a naturally processed HLA-A*02:01-restricted CTL epitope from the human tumor-associated antigen Nectin-4.

Nectin-4 is a tumor antigen present on the surface of breast, ovarian and lung carcinoma cells. It is rarely present in normal adult tissues and is therefore a candidate target for cancer immunotherapy. Here, we identified a Nectin-4 antigenic peptide that is naturally presented to T cells by HLA-A2 molecules. We first screened the 502 nonamer peptides of Nectin-4 (510 amino acids) for binding to and off-rate from eight different HLA class I molecules. We then combined biochemical, cellular and algorithmic assays to select 5 Nectin-4 peptides that bound to HLA-A*02:01 molecules. Cytolytic T lymphocytes were obtained from healthy donors, that specifically lyzed HLA-A2(+) cells pulsed with 2 out of the 5 peptides, indicating the presence of anti-Nectin-4 CD8(+) T lymphocytes in the human T cell repertoire. Finally, an HLA-A2-restricted cytolytic T cell clone derived from a breast cancer patient recognized peptide Nectin-4145-153 (VLVPPLPSL) and lyzed HLA-A2(+) Nectin-4(+) breast carcinoma cells. These results indicate that peptide Nectin-4145-153 is naturally processed for recognition by T cells on HLA-A2 molecules. It could be used to monitor antitumor T cell responses or to immunize breast cancer patients.

DNA methylation profiling reveals a predominant immune component in breast cancers.

Breast cancer is a molecularly, biologically and clinically heterogeneous group of disorders. Understanding this diversity is essential to improving diagnosis and optimizing treatment. Both genetic and acquired epigenetic abnormalities participate in cancer, but the involvement of the epigenome in breast cancer and its contribution to the complexity of the disease are still poorly understood. By means of DNA methylation profiling of 248 breast tissues, we have highlighted the existence of previously unrecognized breast cancer groups that go beyond the currently known 'expression subtypes'. Interestingly, we showed that DNA methylation profiling can reflect the cell type composition of the tumour microenvironment, and in particular a T lymphocyte infiltration of the tumours. Further, we highlighted a set of immune genes having high prognostic value in specific tumour categories. The immune component uncovered here by DNA methylation profiles provides a new perspective for the importance of the microenvironment in breast cancer, holding implications for better management of breast cancer patients.