Biomedical subjects

S Ménard

Publications and source records attributed to S Ménard.

190 records · Page 11Linked to original sources

PubMedDate not supplied

Production of a monoclonal antibody directed against the recombinant SEL1L protein.

SEL1L, highly similar to the C elegans sel-1 gene, is a recently cloned human gene whose function is under investigation. SEL1L is differentially expressed in tumors and normal tissues and seems to play a role in tumor growth and aggressiveness. We used the recombinant N-terminus of the SEL1L protein to immunize a Balb/c mouse and produce a monoclonal antibody. A hybridoma secreting an antibody specifically reacting on the SEL1L recombinant fragment was selected. This monoclonal antibody, named MSel1, recognizes the SEL1L protein by Western blotting, immunofluorescence and immunohistochemistry on normal and tumor cells. MSel1 is able to recognize SEL1L even on archival tumor specimens and is therefore particularly appropriate to study SEL1L involvement in tumor progression.

Animals↗

PubMedDate not supplied

A double determinant radioimmunoassay Mov2-MOv8 for monitoring ovarian carcinomas: definition of the methodology.

A double-determinant radioimmunoassay for the detection of circulating antigens associated with human ovarian carcinoma was developed using two monoclonal antibodies: MOv2 and MOv8 employed respectively as catcher and tracer. The development of the method through three different procedures enabled us to detect the presence of CaMOv2-CaMOv8 carrying molecules in 14 out of 15 ascitic fluids from ovarian carcinoma patients whose tumors were found to be positive with MOv2 and MOv8 monoclonal antibodies by immunofluorescence. Moreover, 13 out of 15 ovarian carcinoma patients presented high levels of antigen in their serum (60-170 Ua/ml). Low levels of antigen were observed in the normal population, the values ranging from 30-40 Ua/ml. However, in 13 out of 100 apparently healthy women high levels of antigen were found in the serum.

Adult↗

PubMedDate not supplied

Hybrid antibodies in cancer diagnosis and therapy.

Monoclonal Antibodies (Mabs) represent a promising tool for cancer diagnosis and therapy. Administration of MAbs alone or conjugated to cytotoxic agents has been attempted but has significant limitations. Another potentially effective approach is the use of bispecific or bifunctional antibodies where the capacity to recognize the tumor cell and the toxic agent or lymphocyte activation molecule are united in one MAb. The hybrid molecule can be produced by chemical linkage between the two parental antibodies, or alternatively by a biological approach that consists in the fusion of the two selected hybridomas. In the resulting quadroma cell the hybridoma immunoglobulin chains recombine randomly to form the bifunctional MAb. In different in vitro and in vivo models, bifunctional MAbs against tumor and CD3 at nanomolar concentration has been shown to promote tumor cell killing by cytotoxic T cells. Specific localization of chemotherapeutic drugs in xenografted tumors has been demonstrated in mice pretreated with hybrid MAbs. The advantages of the hybrid MAb approach are that it should reduce the MAb biodistribution problem and that it involves no chemical manipulation between the functional agent and the MAb molecules.

Antibodies, Monoclonal↗

PubMedDate not supplied

Detection of Lewis(a) antigen in sera of ovarian carcinoma patients by MOv2-MOv8 double-determinant radioimmunoassay.

The monoclonal antibodies MOv2 and MOv8, raised against ovarian carcinoma, were found to be directed against two non-crossreacting epitopes expressed on the same molecule. Immunochemical analysis of the MOv8 recognized epitope showed that the Le(a) oligosaccharide, or commercial anti-Le(a) MAb, but not the anti-Le(b) MAb, prevented Ov8 binding to the reference target cell line (SW626), indicating that it is carried by the Le(a) antigen. Since we previously reported that MOv2 also recognises the Le(a) antigen, these data suggest that Mov8 and Mov2 were directed against different epitopes on the same oligosaccharide chain. Bearing in mind the knowledge of the biochemical nature of the monoclonal antibody recognized epitopes (CaMOv2 and CaMOv8), the presence of the circulating molecules recognized by them was analyzed by double determinant immunoradiometric assay (DDIRMA) in 103 sera from ovarian carcinoma patients. Patients with clinical evidence of the disease (ED) with MOv2 and MOv8 reactive and negative tumors had sera reactivity in 67% and 19% respectively. Also, 26% of the patients with no clinical evidence of disease (NED) had positive sera. When we investigated the relationship between MOv2-MOv8 DDIRMA sera positivity and red blood cells (RBC) Lewis phenotype, a strong correlation was found between the Le(a)+ phenotype and DDIRMA sera reactivity in healthy donors (6/6) and in ovarian carcinoma patients (9/10) whatever their clinical condition. No Le(a)- healthy donors gave evidence of MOv2-MOv8 reactive sera. In contrast, 33% and 57% of the sera from ED carcinoma patients with respectively Lea-b+ and Lea-b- phenotype were positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMedDate not supplied

Production of monoclonal antibodies against a new carcinoma-associated marker in view of developing a serological test.

By immunizing a mouse with human metastatic breast tumor cells from patient effusions and infiltrated lymph nodes, a monoclonal antibody (MLuC2), which identifies a new carcinoma-associated marker, was raised. The reactivity of this reagent was studied by immunohistochemistry on live and fixed cells from tumor cell lines and on frozen sections from surgical specimens. Besides reacting with 73% of breast carcinomas, MLuC2 also reacted with 93% of non-small cell lung carcinoma (NSCLC) and with a few normal tissues. The MLuC2-recognized molecule (CaMLuC2), whose MW was 90 KDa according to immunoblotting experiments, was found to be detectable in the serum and could therefore be of particular interest for serological diagnostic applications. Since the CaMLuC2 epitope was not polyexpressed on the bearing molecule, we produced a new generation of MAbs in order to define epitopes coexpressed with CaMLuC2 on the same 90 kDa molecule, and which are therefore suitable to develop a double-determinant immunoradiometric assay (DDIRMA) for the detection of this marker in the sera of lung carcinoma patients. Different analyses by immunohistochemistry, binding inhibition tests and DDIRMA, proved that the two new reagents developed, MLuC8 and MLuC9, recognize the same or closely related epitopes, which are however different from CaMLuC2, but which are all present on the same molecule. Preliminary immunoradiometric tests performed on sera from lung cancer and control patients showed a good specificity but a low sensitivity. In fact, only 42% of the 28 tested sera samples from NSCLC patients scored positive despite the fact that more than 90% of the NSCLC expressed the relevant antigen.

Antibodies, Monoclonal↗

PubMedDate not supplied

Study of a soluble tumor-associated marker composed of CEA related molecules recognized by three monoclonal antibodies.

Three MAbs, MLuC2, MLuC8 and MLuC9, directed against a molecule that is produced and secreted by carcinoma cells were studied with the aim of developing a double-determinant immunoradiometric assay (DDIRMA). We demonstrated by means of immunoblotting, immunodepletion and DDIRMA techniques, that MLuC9 reacted against the CEA molecule, whereas MLuC2 and MLuC8 reacted against a 90 Kd molecule related to CEA. The DDIRMA performed with the anti-CEA as a catcher MAb and the anti-90 Kd as a tracer MAb was found to be positive with the HT29 soluble extract, which suggests the existence of CEA/90 Kd dimeric molecules. The same reactivity was found when sera from patients with lung carcinomas were tested, which excludes that this molecule could be an artefact due to the cell solubilization procedures. The association between CEA and the 90 Kd molecule was further confirmed by immunodepletion experiments in which the immunoprecipitation with one MAb not only removed the recognized molecule, but also partially immunodepleted the material from the other.

Antibodies, Monoclonal↗

PubMedDate not supplied

Conventional antibodies: requirements and methods for their optimization.

Eighteen years after the discovery of monoclonal antibodies (MAbs), the debate as to whether these reagents have fulfilled their promise must now be addressed. When MAbs were studied as tools for diagnosis and therapy, problems arose regarding the reagents themselves and the recognized target antigens. Because most MAbs are of murine origin, they usually evoke an immune response in human patients, which reduces their effectiveness. Moreover, their bulky size and dispersal via the blood prevent most of the injected antibodies from substantially penetrating solid, poorly vascularized tumors. However, MAbs that are adequately selected and manipulated to circumvent these problems have been found to successfully image tumors and to be therapeutically active.

Antibodies, Monoclonal↗

PubMedDate not supplied

Production and characterization of monoclonal antibodies directed against the laminin receptor precursor.

The 67-kDa laminin receptor (67LR) is an important tumor marker whose molecular structure has not yet been fully elucidated. To shed new light on this molecule, we raised a series of eight new monoclonal antibodies, designated MPLR1 to 8, directed against the 37-kDa recombinant laminin receptor precursor (37LRP). Cross-competition experiments demonstrated that the epitopes recognized by MPLR2, 4 and 5 partially overlap, since MPLR4 and 5 compete with labelled MPLR2 for the binding to recombinant 37LRP. These three antibodies belong to the IgG1 class, whereas the other ones are all IgM. Presumably due to the fact that they are directed against partially unfolded antigenic determinants expressed on the recombinant protein, MPLRs did not recognize the native protein. Indeed, they showed no reactivity at the membrane level in cytofluorimetric analysis and they did not work in immunoprecipitation experiments. In contrast, these reagents are valuable tools in immunoblotting, since they clearly identify a 67-kDa protein (the mature laminin receptor) in addition to the 37-kDa precursor form. MPLRs are thus a new powerful tool which could help in the characterization of the still enigmatic 67LR molecule.

Animals↗

PubMedDate not supplied

c-erbB-2 expression in primary breast cancer.

c-erbB-2 is an oncoprotein which is overexpressed in up to 40% of primary breast cancers. c-erbB-2 overexpression is a bad prognostic factor in patients with lymph node-positive disease. Unfortunately, there has been no agreement to date on whether c-erbB-2 overexpression is of prognostic significance in patients with lymph node-negative disease. c-erbB-2 overexpression is correlated with the absence of estrogen receptor expression in a number of publications. Correlation between c-erbB-2 overexpression and hormone sensitivity in the clinical setting is less well established and is the focus of ongoing studies. Both preclinical and clinical studies support an association between c-erbB-2 receptor overexpression and resistance to alkylating agents. In contrast, the data for c-erbB-2 and anthracyclines should be viewed in a slightly different manner. Anthracyclines appear to have a greater therapeutic effect in c-erbB-2-positive disease which may be dose sensitive. In c-erbB-2-negative disease not only is the therapeutic effect reduced but there does not appear to be any improved response to higher doses of anthracyclines. The data for c-erbB-2 and the taxanes is still not clear enough to provide any definite conclusions. If there is a correlation it would at present appear to be between paclitaxel and response rates, but this needs to be confirmed in larger studies. Few studies have looked at changes in c-erbB-2 on therapy. Those that have seem to show no significant change on either tamoxifen or chemotherapy.

Breast Neoplasms↗

PubMedDate not supplied

Production of a monoclonal antibody directed against the high-affinity nerve growth factor receptor.

The high-affinity nerve growth factor receptor corresponds to the tyrosine protein kinase encoded by the proto-oncogene trkA. Different findings suggest that nerve growth factor (NGF) can be operative in the growth modulation of tumor cell lines possessing high-affinity binding sites for this molecule. Using as immunizing material the SKNBE neuroblastoma cell line transfected with proto-trkA we produced a monoclonal antibody (MAb) able to recognize the high-affinity nerve growth factor receptor. The selected MAb, designated MGR12, is directed against an epitope present on the extracellular domain of the receptor since it showed reactivity on living trkA-expressing cells and was able to immunoprecipitate the proto-trkA molecule. The MGR12 MAb is directed against a non-functional epitope since it neither inhibited NGF binding nor induced receptor internalization. This new reagent appears to be an appropriate tool for analyzing the expression of high-affinity nerve growth factor receptor in tumors of different origin and for elucidating its involvement in tumor progression.

3T3 Cells↗