Single chain variable fragments (scFv) antibodies have been fused obtaining diabodies, improving scFv properties converting in a promising therapy. Three diabodies d-shMFE, d-B3 and d-CB4 were developed against CEA antigen (d-shMFE23), integrin vd-B6-3and bispecific for both antigens (CB4). Cell adhesion andmigration assay have been carried out in tumor cells in order to study the effects of these diabodies. Our aim is to probe that diabodies are specific for both antigens and they block cell adhesion and migration through different extracellular matrix proteins (ECM).
Antibodies have become a therapeutic agent used in a range of diseases such cancer, multiple sclerosis, inflammatorydiseases, macular degeneration, transplant rejection (Kerbrat et al. 2011, Coiffer et al, 1998, Luan et al, 2011; Seider et al, 2001) . Their clinical applications in cancer have increased in the recent year being one of the therapies with more future perspective due to their versatility as therapeutic agents.
Development of antibodies has evolved over the years, starting in 1975 with theproduction of murine monoclonal antibodies by Kohler and Milsteim and ending with recombinant antibody engineering. Small antibodies fragments have been generated to overcome the limitations of the whole antibody such as background in imaging, myelotoxicity in therapeutics applications and undesirable effects triggered by the Fc fragment (Maneesh et al, 2007).
Recombinant technology has allowedproduction of small antibody fragments called single chain variable fragment (scFv). ScFv consists in the variable heavy and light chain of an antibody fused by a neutral linker, keeping the antigen binding site of an antibody. The antigen binding site is composed by six complement determining region (CDRs); these are hypervariable regions within the variable regions that give the specificity to theantibody (Söderlind et al, 1999).
ScFv are monospecific in binding and have short serum life (< 10 min) due to their small size (27kDa). In order to improve this disadvantage, diabodies were undertaken. Diabodies consist of the fusion of two scFV by non covalent association, covalent association or using a peptide linker. Diabodies increase binding avidity and the serum half life, being moresuccessful penetrating solid tumors. (Maneesh et al, 2007).
Cancer targets are proteins or molecules that during tumorigenesis are overexpressed comparing with normal epithelium or the bio-distribution of the protein is altered. In our study we are going to target two proteins, one of them overexpressed during tumor progression, the integrin αvβ6, and the carcinoembryonic antigen whichbio-distribution is altered.
Integrins are a family of heterodimeric membrane glycoproteins. Integrin family members mediates cell-cell adhesion and adhesion and attachment to different extracellular matrix proteins (ECM), soluble proteins, pathogens and growth factors (Wipff et al, 2008). Theses membrane proteins are involved in transmitting bidirectional signaling form both sided of the plasma membraneinteracting with the cytoskeleton adaptor proteins controlling the ligand interaction in the other hand the extracellular proteins ligand binding can modulate cytoskeleton adaptor proteins (Huvenners et al, 2009). Furthermore integrins regulate cellular processes such as proliferation, migration, cell survival, cell adhesion and migration. (GJ Thomas et al, 2001a) Hence, deregulated expression ofthese integrin in cancer cells has been shown to promote migration, tumor invasion and metastasis.
Integrinvis not expressed in human healthy adult epithelium, although it is detected during embryonic development, inflammation and wound healing (Breuss et al, 2005). These integrin is also overexpressed in some cancers such as in colorectal carcinoma, cervical carcinoma, non-small cell...