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A Ménoret

Publications and source records attributed to A Ménoret.

At least 19 recordsLinked to original sources
PubMed2001

An endoplasmic reticulum protein implicated in chaperoning peptides to major histocompatibility of class I is an aminopeptidase.

gp96, an abundant peptide-binding chaperone of the lumen of the endoplasmic reticulum and an acceptor of peptides transported into the endoplasmic reticulum through transporter associated with antigen processing, is shown to be an aminopeptidase. gp96 can trim an amino-terminal extended 19-mer precursor of the K(b)-binding VSV8 epitope for recognition by the cognate cytotoxic T lymphocyte clone. These observations support a role for gp96 in the amino-terminal trimming of extended peptides in the endoplasmic reticulum.

Aminopeptidases↗
PubMed2001

Phylogenetic conservation of the molecular and immunological properties of the chaperones gp96 and hsp70.

The heat shock proteins (HSP) gp96 and hsp70 have been shown to have a critical role in eliciting adaptive immune responses to cancers and viruses. This role derives from (i) their ability to chaperone antigenic peptides generated in the cells from which the HSP are isolated, and (ii) their capacity to interact with antigen presenting cells (APC) which re-present the HSP-chaperoned peptides in context of MHC I molecules. We have asked whether the immunological properties of HSP extend beyond the mammals to other phyla. We report here the serological, biochemical, genetic, and immunological characterization of the Xenopus gp96. Like mammalian gp96, Xenopus gp96 forms non-covalent complexes with peptides. Immunization with gp96 and hsp70 purified from Xenopus tumors, elicits potent and specific anti-tumor immunity, which is dependent on their ability to chaperone peptides in vivo. An immunogenic peptide chaperoned by the Xenopus gp96 can be processed and presented by mouse APC, to antigen-specific CD8+ T cells of mice. The remarkable conservation of these essential immunological properties of gp96 and hsp70 between amphibians and mammals suggests the importance of HSP in the evolution of the vertebrate immune system.

Amino Acid Sequence↗
PubMed2001

The inducible Hsp70 as a marker of tumor immunogenicity.

Growing evidence indicates that the stress response in general and heat shock proteins (Hsps) in particular have a profound impact on tumor immunogenicity. In this study, we show that tumor cells subjected to a nonlethal heat shock stress are unable to form tumors in syngenic mice, whereas they do so in athymic nude mice. Moreover, heat-shocked MethA immunity is tumor specific. Enhancement of T-cell-mediated immunogenicity correlates with the expression of the inducible Hsp70 but not the constitutive Hsc70. These observations have a bearing on the proposed functional role of Hsp-peptide association in antigen processing and presentation by major histocompatibility complex I molecules under normal and stressful conditions.

Adenocarcinoma↗
PubMed2000

Saturation, competition, and specificity in interaction of heat shock proteins (hsp) gp96, hsp90, and hsp70 with CD11b+ cells.

Heat shock proteins (hsp(s)) have been postulated to interact with APCs through specific receptors, although the receptors are yet to be identified. Specificity, saturation, and competition are the three defining attributes of a receptor-ligand interaction. We demonstrate here that the interaction of the heat shock proteins gp96 and hsp90 with CD11b+ cells is specific and saturable and that gp96 can compete with itself in gp96-macrophage interaction. Interestingly, the phylogenetically related hsp90 also competes quite effectively with gp96 for binding to macrophages, whereas the unrelated hsp70 does so relatively poorly, although it binds CD11b+ cells just as effectively. These data provide evidence that the heat shock proteins interact with APCs with specificity and for the existence of at least two distinct receptors, one for gp96 and hsp90 and the other for hsp70.

Animals↗
PubMed2000

Purification of multiple heat shock proteins from a single tumor sample.

Heat shock protein-based vaccines have been shown to immunize against cancer and infectious diseases in both prophylactic and therapeutic protocols. So far, four classes of heat shock proteins (HSPs) preparation: gp96, HSP90 (hsp86, hsp84), HSP70 (hsc70, hsp70) and calreticulin have been used successfully. The methods for purifying them individually are now readily available. However, since tumors are not always available in large quantity, a major challenge remains the development of a procedure to simultaneously isolate these HSPs from the same sample. We report here that hsp40, hsp60, hsc70, hsp70, hsp84, hsp86, and gp96 (grp94) but not BiP (grp78) and calreticulin can be separated from a single tumor sample in one step using heparin-agarose chromatography. Interestingly this procedure separates the HSP70 isoforms hsp70 from hsc70, but not the HSP90 isoforms hsp84 and hsp86. The three main immunogenic HSPs, gp96, hsp86/84, and hsc70 can be further isolated to homogeneity using additional purification methods. In addition, we have shown that the interaction of the chaperoned peptides with hsc70 and gp96 is not compromised during heparin chromatography. These observations provide a new method for preparation of multiple HSP-based vaccines, circumventing the sample size limitation, as well as providing the possibility to study how multiple HSPs can synergize in eliciting immunity.

Animals↗
PubMed2000

Natural autoantibodies against heat-shock proteins hsp70 and gp96: implications for immunotherapy using heat-shock proteins.

Immunization of mice with cognate cancer-derived heat-shock protein (hsp) preparations leads to protection from cancer growth. As hsp used for vaccination or therapy are derived from autologous cancers, questions of pathological autoimmunity are of immense significance for the ongoing translation of this approach to therapy of human cancer. Employing the sera of normal adult mice as the first antibody, highly sensitive immunoblotting revealed the presence of anti-hsp natural autoantibodies in healthy animals. Natural autoantibodies of the immunoglobulin D (IgD) isotype bind to gp96, whereas hsp70 was recognized by IgD and IgM autoantibodies. Neither hsp was recognized by the IgA, IgE or IgG immunoglobulins contained in the serum. The antigen-antibody recognition was titratable and dependent on the integrity of the IgD molecule. Sera from only a subset of the animals tested were found to be positive for autoantibodies against gp96 and hsp70, and individual and strain-specific variations were detected. Injection of gp96 into healthy mice did not show sustained or consistent anti-gp96 IgD antibody response, class switching, toxicity or pathological autoimmunity. IgD autoantibodies against gp96 and hsp70 were also not detected in the autoimmune lpr mice. These observations show the existence of a measured and tightly regulated natural immune response to hsp.

Animals↗
PubMed1999

Cell surface expression of the endoplasmic reticular heat shock protein gp96 is phylogenetically conserved.

In mammals, the heat shock protein gp96 complexed to antigenic peptides elicits T cell adaptive immunity. By itself, however, gp96 can evoke responses that are characteristic of innate immunity. Interestingly, this protein, which resides in the endoplasmic reticulum, is expressed on the surface of certain mouse tumor cells. Given that heat shock proteins are highly conserved, we investigated whether the cell surface expression of gp96 is also evolutionarily conserved. Our data reveal that gp96, most likely containing the endoplasmic reticulum retention motif (KDEL), is expressed on the surface of three different Xenopus lymphoid tumor cell lines, each derived from a different spontaneously arising thymic tumor. Levels of expression differ among the tumor lines tested, with more immunogenic tumors expressing greater amounts of surface gp96. Moreover, a high level of gp96 surface expression is detectable on a subset of Xenopus normal nontransformed splenic lymphocytes (mainly surface IgM+ B cells) but not on other normal cells, including macrophages and nucleated erythrocytes. Surface expression of a gp96 protein homologue occurs also on some, but not all, T and B cell clones derived from peripheral blood cells of the channel catfish, as well as on lymphocyte-like cells, but not on erythrocytes from the hagfish, a primitive agnathan vertebrate lacking markers of an adaptive immune system. gp96 is actively directed to and retained on the plasma membrane of Xenopus lymphocytes and tumor cells and hagfish lymphocyte-like cells by a process that requires vesicular transport. This selective surface expression of gp96 on some immune cells from different vertebrate classes is consistent with an ancestral immunological role of gp96 as danger-signaling molecule.

Animals↗
PubMed1999

Association of peptides with heat shock protein gp96 occurs in vivo and not after cell lysis.

Immunization of mice and rats with gp96 preparations isolated from syngeneic cancers has been shown to elicit protective immunity to a number of cancers. The specific immunogenicity of gp96 preparations derives from the antigenic peptides chaperoned by the gp96 molecule and not from gp96 molecules per se. Studies reported here demonstrate that the association of peptides with gp96 occurs in vivo and is not a procedural artifact which occurs in vitro after cell lysis. This demonstration has a bearing on the proposed functional role of HSP peptide association in antigen processing and presentation by MHC I molecules.

Animals↗
PubMed1998

Heat-shock protein-based anticancer immunotherapy: an idea whose time has come.

The heat-shock proteins (HSPs) belong to a family of ubiquitous and abundant proteins used successfully in prophylactic and therapeutic vaccination against tumors. The HSPs are natural chaperones of peptides that reflect the immunologic composition of the cell. Immunization with tumor-derived HSP-peptide complexes (HSP-PC) induces a potent antigen-specific immune response against both the primary tumor and preestablished metastases; the response is restricted to the tumor from which the HSPs are purified. This article describes the manufacturing process of an individual HSP vaccine, and discusses the rationale, feasibility, advantages, and safety of this new approach of cancer immunotherapy in the context of various animal models and of the first HSP clinical trial.

Animals↗
PubMed1997

Purification of immunogenic heat shock protein 70-peptide complexes by ADP-affinity chromatography.

Adenosine triphosphate (ATP)-affinity chromatography has been widely used to purify molecules of the Hsp70 family. This procedure leads to dissociation of peptides from Hsp70 molecules, resulting in Hsp70 preparations devoid of immunological activity. We report that substitution of ATP-affinity chromatography by ADP-affinity chromatography results in isolation of Hsp70 molecules which are still associated with peptides and are immunogenic. The Hsp70 preparations thus obtained contain the constitutive Hsp73 and the inducible Hsp72 molecules. These observations furnish a basis for an analysis of the structural heterogeneity among the members of the Hsp70 family and of the antigenic peptides associated with individual members of this family. They also provide a practical method for the isolation of large quantities of immunologically active Hsp70-peptide preparations.

Adenosine Diphosphate↗
PubMed1995

Co-segregation of tumor immunogenicity with expression of inducible but not constitutive hsp70 in rat colon carcinomas.

Recent results have shown the importance of heat-shock proteins (hsp) in immune reactions. In addition, immunization against hsp purified from some immunogenic tumors specifically protects animals from a challenge with the tumor from which the hsp were purified. The protection is dependent on the association between hsp and immunogenic peptides. Using a model of rat colon carcinoma, we studied the importance of hsp70 expression in determining the tumorigenicity of cancer cells in immunocompetent syngeneic animals. Various clones with distinct tumorigenic potentials have been derived from the same parental tumor. Some clones are tumorigenic and others are rejected through an immune-based mechanism. It was observed that among all parameters tested, immunogenicity of tumors co-segregated with expression of inducible hsp70 but not with constitutive hsc70. Variants were obtained from a highly tumorigenic clone (PROb) and from a regressive clone (REGb). The PROb variant (Ph8), selected by repeated sublethal heat shocks, showed an increased capacity for hsp70 synthesis concomitant with a decreased tumorigenicity. Inversely, the REGb variant (REGR73), selected after in vivo growth in partially immunosuppressed rats, acquired tumorigenicity and lost the ability to synthesize hsp70. Expression of other immunologic mediators such as intercellular adhesion molecule-1, MHC I, and MHC II did not co-segregate with tumor immunogenicity. Depletion experiments showed that the immunity elicited by these tumors involves TCR-alpha beta-bearing T cells. Such observations imply that, in this experimental model, inducible but not constitutive hsp70 is involved in immunogenicity of tumors.

Adenocarcinoma↗
PubMed1995

The expression of carbohydrate blood group antigens correlates with heat resistance.

Recent data indicate that cells may resist heat shock via more than one route: heat shock protein synthesis and other still ill-defined mechanisms. We investigated this phenomenon using four types of cells derived from a single rat colon carcinoma: clones REGb and PROb; PRO A+, a glycosylation variant of PROb selected for its high expression of blood group A antigen; and Ph8, a thermoresistant variant of PROb selected by repeated sublethal heat treatments. Basal heat resistance was clearly associated with the level of cell surface expression of blood group H and A antigens. Biosynthesis of these carbohydrate structures requires two glycosyltransferases, H and A enzymes, whose activities are also correlated with basal heat resistance. In addition, heat sensitive REGb cells were rendered more resistant by transfection with the gene encoding for H enzyme, allowing expression of H antigen. Thus, these terminal glycosylations could play a role as cellular protectors against heat treatment. Blood group carbohydrate antigens were mainly located on O-linked carbohydrate chains of a major glycoprotein of 200 kDa and to a lesser extent on N-linked chains. Only trace amounts were present as glycolipids.

ABO Blood-Group System↗
PubMed1994

Expression of the 100-kda glucose-regulated protein (GRP100/endoplasmin) is associated with tumorigenicity in a model of rat colon adenocarcinoma.

Resistance to glucose starvation and expression of glucose-regulated proteins (grp) were studied in a model of rat colon carcinoma. In this model, various clones originating from the same parental tumor showed distinct tumorigenic potential in syngeneic hosts. Some clones were tumorigenic while others were rejected by an immune-based mechanism. It appeared that the more tumorigenic clones were more resistant to glucose starvation and able to synthesize larger amounts of grp100 than non-tumorigenic clones in response to either glucose starvation or tunicamycin treatment. In contrast, there was no difference in the induced levels of synthesis of grp78 between tumorigenic and non-tumorigenic clones. These results suggest that the ability of cells to synthesize large amounts of the stress protein grp100 might allow them to resist marginal conditions imposed by fully immunocompetent hosts, thus conferring greater tumorigenicity.

Adenocarcinoma↗
PubMed1992

Analysis of factors associated with the tumorigenic potential of 12 tumor clones derived from a single rat colon adenocarcinoma.

We analyzed several factors which could influence the immunogenicity of colon tumor cells, using a series of clones derived from a single chemically induced rat adenocarcinoma cell line. These clones display variable tumorigenic potential in syngeneic immunocompetent animals, and it has been established that in this model the tumorigenicity of the cells depends on their ability to escape immune surveillance. The results show an absence of relationship between tumorigenicity and expression of MHC-class-I antigens, cell adhesion to rat fibroblasts or fibroblast extracellular matrix. The secretion of latent and active TGF beta I appeared to be quite variable from one clone to the other, but was unrelated to tumorigenicity. Unexpectedly, some regressive clones produced elevated levels of this cytokine, suggesting that in this model, spontaneous secretion of TGF beta I is not sufficient to impair the immune system of the host. In contrast, the more tumorigenic clones were more resistant than less tumorigenic ones to cytotoxicity mediated by NK or LAK cells. They also showed arrest of cell proliferation after reaching confluence, something not observed in the less tumorigenic clones. Finally, the strongest relationship with tumorigenicity was found for expression of blood-group carbohydrate antigens. Increased expression of blood-group-H antigen and, conversely, decreased expression of beta-galactoside precursors of this antigen correlated with increased tumorigenicity.

Adenocarcinoma↗
PubMed1992

[Characterization of autoantigen (p105) in a model of colonic adenocarcinoma in the rat].

Sera from BDIX rats bearing the syngeneic colon tumors PROb or REGb were analysed by Western blotting in order to detect a possible humoral response against the grafted tumor. The PROb clone grows progressively in syngeneic hosts and metastasizes, whereas the REGb clone grows slowly and then is rejected. This model was developed by F Martin and his group in Dijon, France. We observed that rats bearing PROb tumors only develop an antibody response against a water-soluble protein of 105 kDa (p105) which is expressed by both tumor clones. This antibody response has never been detected in rats bearing REGb tumors. The antigen p105 was also expressed by normal adult colon as well as some other foetal or adult tissues. It is also present in extracts from several tumor cell lines including human colorectal carcinoma cell lines. Moreover, the titer of detected antibody at day 30 was inversely correlated with the survival of rats after tumor inoculation, suggesting a possible facilitating role of this antibody response.

Adenocarcinoma↗
PubMed1991

Analysis of the state of differentiation of two rat colon carcinoma clones with distinct tumorigenic properties.

The presence of some characteristics of normal rat intestinal epithelial cells was studied on two clones originating from a single rat colon carcinoma. These clones differed by their tumorigenic properties in the syngeneic host. However, they grow similarly in vitro and in immuno-deprived animals. The PROb clone which had the ability to form progressive tumors in the syngeneic host appeared to possess more features of differentiated cells than the REGb clone which was immunologically rejected by syngeneic hosts. Indeed, the morphology of the cells was different, the REBb cells having a more fibroblastic appearance while the PROb cells had the capacity to form domes characterizing the functional polarization of the cell layer. The two clones could also be distinguished by their expression of proteins of intermediate filaments. Both expressed cytokeratins showing their epithelial origin, but only REGb cells displayed vimentin which is characteristic of mesenchymal or poorly differentiated epithelial cells. Furthermore, analysis of the expression of a series of glycoconjugate tissue antigens and an unknown protein (p120) showed that the PROb cells resembled more the normal adult digestive epithelium than the REGb cells did. In conclusion, it appears that in this model, the most aggressive cells, those resisting to the constraints imposed by the immune system, are also the more differentiated ones.

Adenocarcinoma↗