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C Lurquin

Publications and source records attributed to C Lurquin.

31 records · Page 2Linked to original sources
PubMed1994

Sequence and expression pattern of the human MAGE2 gene.

We reported previously identification of the human MAGE1 gene, which encodes an antigen recognized on human melanoma MZ2-MEL by autologous cytolytic T lymphocytes. In addition to MAGE1, melanoma MZ2-MEL expresses several closely related genes, one of which has been named MAGE2. The complete MAGE2 sequence was obtained and it comprises 3 exons homologous to those of MAGE1 and an additional exon homologous to a region of the first MAGE1 intron. Like the open reading frame of MAGE1, that of MAGE2 is entirely encoded by the last exon. The MAGE1 and MAGE2 sequences of this exon show 82% identity and the putative proteins show 67% identity. The MAGE2 gene is expressed in a higher proportion of melanoma tumors than MAGE1. It is also expressed in many small-cell lung carcinomas and other lung tumors, laryngeal tumors, and sarcomas. No MAGE1 and MAGE2 gene expression was found in a large panel of healthy adult tissues, with the exception of testis.

Amino Acid Sequence↗
PubMed1994

Structure, chromosomal localization, and expression of 12 genes of the MAGE family.

We reported previously that human gene MAGE-1 directs the expression of a tumor antigen recognized on a melanoma by autologous cytolytic T lymphocytes. Probing cosmid libraries with a MAGE-1 sequence, we identified 11 closely related genes. The analysis of hamster-human somatic cell hybrids indicated that the 12 MAGE genes are located in the q terminal region of chromosome X. Like MAGE-1, the 11 additional MAGE genes have their entire coding sequence located in the last exon, which shows 64%-85% identity with that of MAGE-1. The coding sequences of the MAGE genes predict the same main structural features for all MAGE proteins. In contrast, the promoters and first exons of the 12 MAGE genes show considerable variability, suggesting that the existence of this gene family enables the same function to be expressed under different transcriptional controls. The expression of each MAGE gene was evaluated by reverse transcription and polymerase chain reaction amplification. Six genes of the MAGE family including MAGE-1 were found to be expressed at a high level in a number of tumors of various histological types. None was expressed in a large panel of healthy tissues, with the exception of testis and placenta.

Amino Acid Sequence↗
PubMed1992

A nonapeptide encoded by human gene MAGE-1 is recognized on HLA-A1 by cytolytic T lymphocytes directed against tumor antigen MZ2-E.

We have reported the identification of human gene MAGE-1, which directs the expression of an antigen recognized on a melanoma by autologous cytolytic T lymphocytes (CTL). We show here that CTL directed against this antigen, which was named MZ2-E, recognize a nonapeptide encoded by the third exon of gene MAGE-1. The CTL also recognize this peptide when it is presented by mouse cells transfected with an HLA-A1 gene, confirming the association of antigen MZ2-E with the HLA-A1 molecule. Other members of the MAGE gene family do not code for the same peptide, suggesting that only MAGE-1 produces the antigen recognized by the anti-MZ2-E CTL. Our results open the possibility of immunizing HLA-A1 patients whose tumor expresses MAGE-1 either with the antigenic peptide or with autologous antigen-presenting cells pulsed with the peptide.

Amino Acid Sequence↗
PubMed1992

Efficient expression of tum- antigen P91A by transfected subgenic fragments.

Mutagen treatment of mouse P815 tumor cells produces immunogenic mutants that express new transplantation antigens (tum- antigens) recognized by cytolytic T cells. The gene encoding tum- antigen P91A comprises 12 exons and a mutation located in exon 4 is responsible for the production of a new antigenic peptide. Transfection experiments showed that the expression of the antigen could be transferred not only by the entire gene but also by gene segments comprising only the mutated exon and parts of the surrounding introns. This was observed with subgenic regions that were not cloned in expression vectors. Antigen expression did not require the integration of the transfected gene segment into a resident P91A gene by homologous recombination. It also occurred when the subgenic segment was transfected without the usual selective gene, which comprises an eucaryotic promoter, and also without plasmid sequences, which are known to contain weak promoters. When a stop codon was introduced at the beginning of exon 4, the expression of the antigen was maintained and evidence was obtained that an ATG codon located in this region served as initiation site for the translation of the antigenic peptide. But we have not obtained evidence indicating that antigenic peptides are direct translation products rather than degradation products of entire proteins.

Amino Acid Sequence↗
PubMed1992

Identification of tumour rejection antigens recognized by T lymphocytes.

On the basis of the results reviewed here, there are two major mechanisms whereby tumour rejection antigens may arise. The first mechanism is mutational. Point mutations occurring in a large variety of genes may produce new antigenic peptides, either by providing them with the ability to bind to MHC class I molecules or by providing them with a new epitope (Fig. 2). The second mechanism is the activation of a gene that is silent in normal tissues and for which no strong natural tolerance has been established. Plausible candidates for the mutational mechanism are the "tumour specific transplantation antigens" observed on methylcholanthrene induced tumours and tumours induced by ultraviolet light. The diversity of these antigens appears to be very large, like that of the tum- antigens. Moreover, these tumours have been obtained with high doses of carcinogens, which are proven mutagens. On the other hand, a P815 tumour rejection antigen appears to arise through the activation of a silent gene, and it may turn out that this is the rule for most tumour rejection antigens. It is our hope that other genes coding for mouse and human tumour rejection antigens will soon be identified, so that it will become clear whether the activational mechanism is the rule or the exception. In our view, this is a crucial issue. Insofar as tumour rejection antigens result from mutations, they may be highly specific for every individual tumour. The tumour specific nature of these antigens would then be easily ascertained. However, active immunization of cancer patients would require that a tumour cell line be obtained from each patient, a most unpractical prospect. If, on the other hand, production of tumour rejection antigens results from the activation of a normal gene, then there is a good probability that the same gene may be activated in many different tumours, being perhaps preferentially shared by tumours of the same histological type. This would probably not result in the expression of the same antigen in all these tumours, because the patients would differ in their presenting molecules, which are determined by their HLA haplotype. However, a subset of the tumours expressing the same "tumour rejection" gene should share the same class I restricting element, so that all of these patients could be immunized with a cell that would express the gene and carry the appropriate HLA molecule.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

A gene encoding an antigen recognized by cytolytic T lymphocytes on a human melanoma.

Many human melanoma tumors express antigens that are recognized in vitro by cytolytic T lymphocytes (CTLs) derived from the tumor-bearing patient. A gene was identified that directed the expression of antigen MZ2-E on a human melanoma cell line. This gene shows no similarity to known sequences and belongs to a family of at least three genes. It is expressed by the original melanoma cells, other melanoma cell lines, and by some tumor cells of other histological types. No expression was observed in a panel of normal tissues. Antigen MZ2-E appears to be presented by HLA-A1; anti-MZ2-E CTLs of the original patient recognized two melanoma cell lines of other HLA-A1 patients that expressed the gene. Thus, precisely targeted immunotherapy directed against antigen MZ2-E could be provided to individuals identified by HLA typing and analysis of the RNA of a small tumor sample.

Antigens, Neoplasm↗
PubMed1989

Structure of the gene of tum- transplantation antigen P91A: the mutated exon encodes a peptide recognized with Ld by cytolytic T cells.

Mutagen treatment of mouse P815 tumor cells produces immunogenic mutants that express new transplantation antigens (tum- antigens) recognized by cytolytic T cells. We found that the gene conferring expression of tum- antigen P91A contains 12 exons, encoding a 60 kd protein lacking a typical N-terminal signal sequence. The sequence shows no significant similarity with sequences in current data bases. A mutation that causes expression of the antigen is located in exon 4; it is the only apparent difference between the normal and the antigenic alleles. A short synthetic peptide corresponding to a region of exon 4 located around this mutation makes P815 cells sensitive to lysis by anti-P91A cytolytic T cells. The mutation creates a strong aggretope enabling the peptide to bind the H-2 Ld molecule. Several secondary tumor cell variants that no longer express tum- antigen P91A were found to carry deletions in the gene.

Amino Acid Sequence↗
PubMed1988

Immunogenic (tum-) variants of mouse tumor P815: cloning of the gene of tum- antigen P91A and identification of the tum- mutation.

Mutagen treatment of mouse P815 tumor cells produces tum- variants that are rejected by syngeneic mice because these variants express new surface antigens. These "tum- antigens" are recognized by cytolytic T lymphocytes but induce no detectable antibody response. Transfection of P815 cell line P1.HTR with DNA of tum- variant P91 yielded transfectants expressing tum- antigen P91A. They were detected by their ability to stimulate proliferation of cytolytic T lymphocytes [Wölfel, T., Van Pel, A., De Plaen, E., Lurquin, C., Maryanski, J. L. & Boon, T. (1987) Immunogenetics 26, 178-187]. A cosmid library of a cell line expressing antigen P91A was transfected into P1.HTR. Transfectants expressing the antigen were obtained. By packaging directly the DNA of a transfectant with lambda phage extracts, we obtained a small cosmid population containing as major component a cosmid that transferred the expression of P91A. The assay of various restriction fragments of this cosmid led to the isolation of an 800-base-pair fragment containing the P91A sequence required for transfection. Comparison with a homologous cDNA showed that this fragment contained only one of the several exons of the P91A gene. The normal and the tum- forms of the gene differ by one nucleotide located in this 137-base-pair exon. The essential role of this mutation, which produces an amino acid change, was confirmed by site-directed mutagenesis. No significant sequence similarity was found between the 800-base-pair fragment and any recorded gene.

Amino Acid Sequence↗
PubMed1988

Identification of genes encoding T cell defined tum- antigens.

Tum- mutants are immunogenic mutants obtained by mutagen treatment of mouse tumor cells. They express new "tum- antigens" recognized by cytolytic T cells (CTL) but not by specific antibodies. We have recently developed a method aimed at cloning the genes coding for such transplantation antigens. It is based on gene transfection and detection of transfectants by their ability to stimulate CTL. Tum- gene P91A has been isolated. It codes for a 60 kDa protein which does not carry a signal sequence at its N-terminus. The tum- allele differs from its normal counterpart by a point mutation. The sequence of this gene and that of two other tum- genes are totally unrelated with each other and with any sequence presently recorded in data banks. We will try to apply the same cloning method to isolate mouse and human tumor-specific transplantation antigens (TSTA).

Animals↗
PubMed1987

Immunogenic (tum-) variants obtained by mutagenesis of mouse mastocytoma P815. VIII. Detection of stable transfectants expressing a tum- antigen with a cytolytic T cell stimulation assay.

Mutagen treatment of mouse mastocytoma P815 produces highly immunogenic "tum-" variants. Most of these variants express potent transplantation antigens which are not present on the original P815 tumor cells. These tum- antigens, which appear to be specific for each variant, elicit a strong cytolytic T lymphocyte (CTL) response, but do not seem to induce a specific antibody response. As a first step in the isolation of the gene of a tum- antigen, we attempted DNA-mediated gene transfer. As a DNA recipient cell we used P1.HTR, a highly transfectable P815 cell line, whose selection has been previously described. For the detection of antigen-expressing cells in transfected populations we developed a procedure that relies on the ability of these cells to stimulate the proliferation of the relevant CTL. Using DNA from tum- variant P91 mixed with a plasmid carrying an antibiotic resistance gene, we obtained several independent transfectants expressing a tum- antigen, at a frequency of approximately 1 in 13,000 antibiotic-resistant transfectants. These transfectants express only one of the two tum- antigens that were identified on P91, suggesting that these tum- antigens correspond to different genes. We expect that the detection procedure described here will be suitable for the identification of transfectants for any gene that determines the expression of an antigen recognized by CTL.

Animals↗