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F Brasseur

Publications and source records attributed to F Brasseur.

At least 37 records · Page 2Linked to original sources
PubMed1999

HLA-G protein expression is not induced during malignant transformation.

To evaluate the biological relevance of HLA-G expression during tumoral transformation, we analyzed its expression in different malignant cells and immune effector cells infiltrating solid tumors. Our analysis of 33 tumor cell lines and 53 tumoral biopsies demonstrated that: i) six tumor cell lines display HLA-G transcription with differential alternative splicing patterns and only Jeg3 choriocarcinoma and MCF-7 breast adenocarcinoma cell lines express HLA-G translated products; and ii) HLA-G antigens are not expressed in malignantly transformed cells derived from lung (n=18), liver (n=5), colon (n=5), breast (n=10), kidney (n=5), ovary (n=5), and larynx (n=5) tissues ex vivo. The healthy tissues surrounding these tumor tissues do not express HLA-G molecules either. On the other hand, surprisingly, HLA-G products were detected in activated macrophages and dendritic cells localized in tumoral biopsies of 5 out of 18 different lung carcinomas. No HLA-G labelling was observed in resident mononuclear phagocytes of surrounding healthy tissues. Our observations clearly demonstrate that HLA-G is not a marker of malignant cells but appears as a gene expressed in tumor-associated macrophages and dendritic cells, preferentially in those recruited in lung carcinomas. Our findings suggest that specific environmental factors around lung tumors could be involved in the induction of HLA-G protein expression.

Cell Movement↗
PubMed1999

Expression of MAGE and GAGE in high-grade brain tumors: a potential target for specific immunotherapy and diagnostic markers.

The mRNA expression of the tumor-associated antigens MAGE and GAGE was examined in 60 high-grade brain tumors. This analysis was performed by using reverse transcription-PCR, Southern blotting, and sequencing. It was demonstrated that, of the eight GAGE genes, GAGE-2 and -7 were expressed in five of seven normal brains. Four groups of tumors--adult glioblastoma multiforme (n = 20), pediatric glioblastoma multiforme (n = 9), medulloblastomas (n = 15), and ependymomas (n = 14)--were analyzed for mRNA expression. The following frequencies were observed: MAGE-1, 0, 0, 13, and 0%, respectively; MAGE-2, 5, 11, 60, and 57%; MAGE-3 & -6, 0, 0, 13, and 0%; GAGE-1, 65, 11, 13, and 43%; and GAGE-3-6 and -8: 75, 78, 47, and 93%, respectively. Two unclassified tumors expressed GAGE-3-6 and -8 only. The absence of GAGE-1 expression in normal brain, its relatively high frequency of expression in high-grade brain tumors, and its unique 3' sequence, suggest it may represent a useful target for specific immunotherapy. The detection method of reverse transcription-PCR and Southern blotting may also be useful for rapid screening of biopsy specimens both for diagnostic purposes and to determine a patient's eligibility for specific immunotherapy.

Adult↗
PubMed1998

An antigen recognized by autologous CTLs on a human bladder carcinoma.

By stimulating blood lymphocytes with autologous bladder carcinoma cells that had been transfected with B7-1, we obtained a panel of CTL clones which lyse specifically the bladder tumor cells in an MHC class I-restricted fashion. Based on inhibition with anti-HLA Abs and the recognition of allogeneic tumor cells, we could distribute our clones in three groups that recognized three distinct Ags. We characterized one of these Ags by screening a cDNA library prepared with the RNA from this bladder tumor line. This new tumor Ag is a peptide presented by HLA-B4403 molecules. It is produced by a point mutation in a gene that is recorded in databases under the name KIAA0205, is ubiquitously expressed, and whose function is unknown. We also found this mutation in the tumor sample that was originally resected from this patient, but the mutation was not found in the 100 or more independent tumors of various histologic types that were tested. This report is the first to describe the isolation of CTL clones directed against human bladder cancer and the molecular characterization of a bladder tumor Ag.

Antigens, Neoplasm↗
PubMed1998

Reliability of reverse transcription-polymerase chain reaction (RT-PCR)-based assays for the detection of circulating tumour cells: a quality-assurance initiative of the EORTC Melanoma Cooperative Group.

Reverse transcription-polymerase chain reaction (RT-PCR)-based assays detecting occult neoplastic cells are increasingly being used for the study of tumour dissemination and minimal residual disease. However, different methods are employed by various research groups and the results are heterogenous. We prospectively assessed the results from nine laboratories performing tyrosinase RT-PCR assays for the detection of melanoma cells on a series of blind samples. After complete analysis, the results were compared for sensitivity and specificity. All laboratories reported correct results for cDNA standards. Five laboratories attained acceptable specificity and a sensitivity detecting 10 cells in 10 ml of whole blood. Four laboratories had unacceptable specificity and/or sensitivity. This blind study highlights the difficulty of RT-PCR data interpretation and the need for quality assurance between laboratories. Measures to increase the reliability of RT-PCR assays are proposed, which have to be prospectively evaluated in future studies.

DNA, Neoplasm↗
PubMed1998

Mutations of the beta2-microglobulin gene result in a lack of HLA class I molecules on melanoma cells of two patients immunized with MAGE peptides.

Mutations have been identified in the beta2-microglobulin gene of tumor cells of two metastatic melanoma patients who received immunizations with MAGE peptides. One mutation abolishes the start codon whereas the other introduces a premature stop codon. The second beta2-microglobulin allele of both tumors appears to be lost on the basis of sequence data and loss of microsatellite heterozygosity. The lack of beta2-microglobulin gene product results in the absence of HLA class I antigens on the surface of the tumor cells. This may explain why the tumors of both patients progressed despite the immunization treatment and shows the necessity of analyzing in depth the antigen presentation capability of the tumor cells for the interpretation of clinical trials involving anti-tumor vaccination.

Antigens, Neoplasm↗
PubMed1997

Identification of human testis-specific transcripts and analysis of their expression in tumor cells.

Tumor-specific antigens recognized by autologous T lymphocytes are encoded by genes, including those of the MAGE, BAGE, and GAGE gene families, that are expressed in a significant fraction of tumors of various types, but not in normal adult tissues, except for testis where they appear to be expressed in germ cells. Because male germ cells are known to express many genes that are not expressed in other normal adult tissues, we wished to determine whether most of these genes are occasionally activated in tumor cells. Representational difference analysis was used to obtain testis-specific transcripts. The expression of 15 testis-specific cDNA sequences was tested by RT-PCR in a series of tumor cell lines. Only one cDNA sequence showed a significant level of expression in some tumor cell lines. Remarkably, this cDNA clone proved to be a new gene of the MAGE family. These results suggest that MAGE, BAGE, and GAGE genes belong to a minor subset of testis-specific genes that is often activated in tumors of various types, whereas most testis-specific genes are either never or very rarely activated in tumors.

Antigens, Neoplasm↗
PubMed1997

Two members of the human MAGEB gene family located in Xp21.3 are expressed in tumors of various histological origins.

Genes of the MAGE family direct the expression of tumor antigens recognized on a human melanoma by autologous cytolytic T lymphocytes. Twelve closely related MAGE genes are located in the Xq28 region. These genes share 60-98% nucleotide identity in their coding region. The presence of homologous genes in a region of Xp21.3 has been reported previously. We obtained the complete sequence of a 42-kb stretch of this region. It contains four MAGE-related genes, which we propose to name MAGE-B1, B2, B3, and B4 (HGMW-approved symbols MAGEB1, MAGEB2, MAGEB3, and MAGEB4). The coding regions of these genes share 66-81% nucleotide identity and show 45-63% identity with those of the MAGE genes located in Xq28. Like the MAGE genes located in Xq28, the MAGE-B genes are silent in normal tissues with the exception of testis. Like MAGE-1, 2, 3, 4, 6 and 12 (HGMW-approved symbols MAGEA1, 2, 3, 4, 6, and 12), genes MAGE-B1 and MAGE-B2 are expressed in a significant fraction of tumors of various histological types. The transcription of MAGE-B1 and MAGE-B2 can be induced by 5-aza-2'-deoxycytidine, suggesting that the activation of these genes in tumors results from a demethylation process.

Alternative Splicing↗
PubMed1997

A CASP-8 mutation recognized by cytolytic T lymphocytes on a human head and neck carcinoma.

Of the antigens recognized on human tumors by autologous cytolytic T lymphocytes, all those defined thus far have been identified on melanoma or renal cell carcinoma. We report here the identification of an antigen recognized by autologous cytolytic T lymphocytes on a human squamous cell carcinoma of the oral cavity. The antigen is encoded by a mutated form of the CASP-8 gene. This gene, also named FLICE or MACH, codes for protease caspase-8, which is required for induction of apoptosis through the Fas receptor and tumor necrosis factor receptor-1. The mutation, which was found in the tumor cells but not in the normal cells of the patient, modifies the stop codon and adds an Alu repeat to the coding region, thereby lengthening the protein by 88 amino acids. The ability of the altered protein to trigger apoptosis appears to be reduced relative to the normal caspase-8. The antigenic peptide is a nonamer presented by HLA-B*3503. The five last amino acids are encoded by the extension of the reading frame caused by the mutation. This, together with previous observations of CDK4 and beta-catenin mutations, suggests that a significant fraction of the point mutations generating a tumor antigen also play a role in the tumoral transformation or progression.

Aged↗
PubMed1997

Genes coding for melanoma antigens recognised by cytolytic T lymphocytes.

It is now well established that human melanoma cells express antigens that are recognised by cytolytic T lymphocytes derived from the tumour-bearing patient. The molecular definition of these antigens is progressing at an accelerated pace. The currently characterised melanoma antigens can be classified into three categories: differentiation antigens, antigens encoded by genes that are specifically expressed in tumours, and antigens encoded by mutated genes. Several of these antigens are sufficiently tumour-specific to qualify them as candidate anti-cancer vaccines in melanoma patients.

Antigens↗
PubMed1997

MAGE-1 expression threshold for the lysis of melanoma cell lines by a specific cytotoxic T lymphocyte.

Human gene MAGE-1 codes for an antigen that is recognized on a melanoma by an autologous cytotoxic T lymphocyte (CTL). Because MAGE-1 is expressed on a significant proportion of tumours of various histological types and not on normal tissues, the encoded antigen may serve as a target for cancer immunotherapy. Evaluation of the expression of the gene by reverse transcription polymerase chain reaction (RT-PCR) in various tumour samples and tumour cell lines has suggested great variability in the level of expression. It was therefore important to evaluate the minimal level of expression required for lysis by CTL. We tested a number of melanoma cell lines by a quantitative RT-PCR assay to correlate their level of MAGE-1 expression and recognition by the relevant CTL clone. We found that only cell lines expressing more than 10% of the MAGE-1 messenger RNA (mRNA) level of reference cell line MZ2-MEL.3.0 (i.e. more than three mRNA molecules per cell) were lysed by the CTL or induced significant tumour necrosis factor release.

Antigens, Neoplasm↗
PubMed1996

The activation of human gene MAGE-1 in tumor cells is correlated with genome-wide demethylation.

Human gene MAGE-1 encodes tumor-specific antigens that are recognized on melanoma cells by autologous cytolytic T lymphocytes. This gene is expressed in a significant proportion of tumors of various histological types, but not in normal tissues except male germ-line cells. We reported previously that reporter genes driven by the MAGE-1 promoter are active not only in the tumor cell lines that express MAGE-1 but also in those that do not. This suggests that the critical factor causing the activation of MAGE-1 in certain tumors is not the presence of the appropriate transcription factors. The two major MAGE-1 promoter elements have an Ets binding site, which contains a CpG dinucleotide. We report here that these CpG are demethylated in the tumor cell lines that express MAGE-1, and are methylated in those that do not express the gene. Methylation of these CpG inhibits the binding of transcription factors, as seen by mobility shift assay. Treatment with the demethylating agent 5-aza-2'-deoxycytidine activated gene MAGE-1 not only in tumor cell lines but also in primary fibroblasts. Finally, the overall level of CpG methylation was evaluated in 20 different tumor cell lines. It was inversely correlated with the expression of MAGE-1. We conclude that the activation of MAGE-1 in cancer cells is due to the demethylation of the promoter. This appears to be a consequence of a genome-wide demethylation process that occurs in many cancers and is correlated with tumor progression.

Antigens, Neoplasm↗
PubMed1996

Infrequent expression of the MAGE gene family in uveal melanomas.

It has previously been reported that MAGE-1, -2, -3 and -4 genes are expressed in human cancers including cutaneous melanoma. MAGE-1 and MAGE-3 represent targets for specific immunotherapy because they encode peptide antigens which are recognised by cytotoxic T lymphocytes (CTL) when presented by HLA class I molecules, and pilot clinical trials with these peptides are currently in progress. It is likely that other members of the MAGE gene family may also encode antigens recognised by CTL. Uveal melanomas, like cutaneous melanomas, arise from melanocytes that are derived from the neural crest. To determine if uveal melanoma patients would be suitable for MAGE-peptide immunotherapy, the expression of MAGE-1, -2, -3 and -4 genes was assessed by reverse transcription followed by polymerase chain reaction (RT-PCR) amplification and ethidium bromide staining. Expression of MAGE genes was not detected in any of 27 primary tumours. Either MAGE-1 or MAGE-4 was expressed in only 2 of 26 metastatic samples, but expression of MAGE-2 or -3 was not detected. Our data suggest that, unlike cutaneous melanomas, uveal melanomas may not be suitable candidates for MAGE-peptide immunotherapy.

Antigens, Neoplasm↗
PubMed1996

A mutated HLA-A2 molecule recognized by autologous cytotoxic T lymphocytes on a human renal cell carcinoma.

Many human tumor cells have been shown to express antigens that are recognized by autologous cytotoxic T lymphocytes (CTL) and the molecular nature of a number of melanoma antigens has been defined recently. Here we describe the characterization of an antigen recognized on a renal cell carcinoma by autologous CTL clones. This antigen is encoded by the HLA-A2 gene present in the tumor cells. The sequence of this gene differs from the HLA-A2 sequence found in autologous peripheral blood lymphocytes by a point mutation that results in an arginine to isoleucine exchange at residue 170, which is located on the alpha-helix of the alpha 2 domain. Transfection experiments with the normal and mutated HLA-A2 cDNA demonstrated that this amino acid replacement was responsible for the recognition of the HLA-A2 molecule expressed on the tumor cells. The mutant HLA-A2 gene was also detected in the original tumor tissue from the patient, excluding the possibility that the mutation had appeared in vitro. Thus, HLA class I molecules carrying a tumor-specific mutation can be involved in the recognition of tumor cells by autologous CTL.

Aged↗
PubMed1996

A peptide recognized by human cytolytic T lymphocytes on HLA-A2 melanomas is encoded by an intron sequence of the N-acetylglucosaminyltransferase V gene.

A cytolytic T lymphocyte (CTL) clone that lyses many HLA-A2 melanomas was derived from a population of tumor-infiltrating lymphocytes of an HLA-A2 melanoma patient. The gene coding for the antigen recognized by this CTL was identified by transfection of a cDNA library. It is the gene which has been reported to code for N-acetylglucosaminyltransferase V (GnT-V). Remarkably, the antigenic peptide recognized by the CTL is encoded by a sequence located in an intron. In contrast to the fully spliced GnT-V mRNA, which was found in a wide range of normal and tumoral tissues, the mRNA containing the intron region coding for the antigen was not found at a significant level in normal tissues. This mRNA was observed to be present in about 50% of melanomas. Our results suggest that a promoter located near the end of the relevant intron is activated in melanoma cells, resulting in the production of an mRNA coding for the antigen.

Amino Acid Sequence↗
PubMed1995

Expression of MAGE genes in primary and metastatic cutaneous melanoma.

Human genes MAGE-1 and MAGE-3 code for antigens that are recognized on melanoma cells by autologous cytolytic T lymphocytes. These antigens may constitute useful targets for specific anti-tumor immunization of cancer patients, since genes MAGE-1 and MAGE-3 are expressed in a number of tumors of different histological types, but are not expressed in normal adult tissues other than testis. This also applies to genes MAGE-2 and MAGE-4, which are closely related to MAGE-1 and MAGE-3. We have analyzed the expression of these 4 MAGE genes in cutaneous melanoma. Sixteen of 100 primary tumors vs. 69 (48%) of 145 metastases from individual patients expressed MAGE-1. Similar differences in the frequency of gene expression between primary and metastatic tumor samples were observed for MAGE-2, MAGE-3, and MAGE-4. MAGE expression in primary tumors was correlated with tumor thickness: there was a significantly increased frequency in the expression of MAGE-1, -2 and -3 in tumors of greater thickness. Benign and dysplastic nevi, as well as in situ melanomas, did not express any of the 4 MAGE genes.

Adult↗
PubMed1995

Expression of MAGE genes in transitional-cell carcinomas of the urinary bladder.

Human genes MAGE-1 and MAGE-3 code for distinct antigens, which are recognized on melanoma cells by autologous cytolytic T lymphocytes (CTL). These antigens may constitute useful targets for anti-cancer immunotherapy, since no expression of MAGE genes has been observed in normal tissues other than testis. Out of 57 samples of primary transitional-cell carcinomas of the bladder, 12 (21%) expressed MAGE-1 and 20 (35%) expressed MAGE-3. All but one of the tumors expressing MAGE-1 also expressed MAGE-3. Genes MAGE-2 and MAGE-4, which are closely related to MAGE-1 and MAGE-3, were expressed by 30% and 33% of the tumors respectively. MAGE expression was more frequent in advanced tumor stages: 61% of the invasive tumors (stage > or = T2) were positive for expression of at least one of the four genes, whereas only 28% of the superficial tumors (stages Ta and T1) expressed these genes.

Antigens, Neoplasm↗
PubMed1994

Expression of mage genes by non-small-cell lung carcinomas.

Human gene MAGE-I codes for an antigen that is recognized on melanoma cells by autologous cytolytic T lymphocytes (CTL). This antigen is potentially useful as a target for cancer immunotherapy because gene MAGE-I is not expressed in any normal tissues except the testis. We tested 46 surgical samples of non-small-cell lung carcinomas and observed MAGE-I expression in 16 of them (35%). Genes MAGE-2 and 3, which are closely related to MAGE-I, were expressed by a similar proportion of these tumors. Some small-cell lung tumors also express MAGE genes. The proportion of tumors expressing MAGE-I suggests that lung tumor patients may constitute the largest group of patients potentially eligible for pilot studies involving MAGE-I immunization.

Base Sequence↗