title: β-Actin-binding complementarity-determining region 2 of variable heavy chain from monoclonal antibody C7 induces apoptosis in several human tumor cells and is protective against metastatic melanoma.
abstract: Complementarity-determining regions (CDRs) from monoclonal antibodies tested as synthetic peptides display anti-infective and antitumor activities, independent of the specificity of the native antibody. Previously, we have shown that the synthetic peptide C7H2, based on the heavy chain CDR 2 from monoclonal antibody C7, a mAb directed to a mannoprotein of Candida albicans, significantly reduced B16F10 melanoma growth and lung colony formation by triggering tumor apoptosis. The mechanism, however, by which C7H2 induced apoptosis in tumor cells remained unknown. Here, we demonstrate that C7H2 interacts with components of the tumor cells cytoskeleton, being rapidly internalized after binding to the tumor cell surface. Mass spectrometry analysis and in vitro validation revealed that β-actin is the receptor of C7H2 in the tumor cells. C7H2 induces β-actin polymerization and F-actin stabilization, linked with abundant generation of superoxide anions and apoptosis. Major phenotypes following peptide binding were chromatin condensation, DNA fragmentation, annexin V binding, lamin disruption, caspase 8 and 3 activation, and organelle alterations. Finally, we evaluated the cytotoxic efficacy of C7H2 in a panel of human tumor cell lines. All tumor cell lines studied were equally susceptible to C7H2 in vitro. The C7H2 amide without further derivatization significantly reduced lung metastasis of mice endovenously challenged with B16F10-Nex2 melanoma cells. No significant cytotoxicity was observed toward nontumorigenic cell lines on short incubation in vitro or in naïve mice injected with a high dose of the peptide. We believe that C7H2 is a promising peptide to be developed as an anticancer drug.
authors.affiliation: Experimental Oncology Unit (UNONEX), Universidade Federal de São Paulo (UNIFESP), São Paulo SP 04023-062, Brazil.
authors.forename: Denise C
authors.initials: DC
authors.lastname: Arruda
authors.forename: Luana C P
authors.initials: LC
authors.lastname: Santos
authors.forename: Filipe M
authors.initials: FM
authors.lastname: Melo
authors.forename: Felipe V
authors.initials: FV
authors.lastname: Pereira
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Figueiredo
authors.forename: Alisson L
authors.initials: AL
authors.lastname: Matsuo
authors.forename: Renato A
authors.initials: RA
authors.lastname: Mortara
authors.forename: Maria A
authors.initials: MA
authors.lastname: Juliano
authors.forename: Elaine G
authors.initials: EG
authors.lastname: Rodrigues
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Dobroff
authors.forename: Luciano
authors.initials: L
authors.lastname: Polonelli
authors.forename: Luiz R
authors.initials: LR
authors.lastname: Travassos
mesh_terms: D000199:Actins / Q000276:immunology*; D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000276:immunology / Q000494:pharmacology*; D000912:Antibodies, Neoplasm / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002176:Candida albicans / Q000276:immunology; D053148:Caspase 3 / Q000276:immunology; D053181:Caspase 8 / Q000276:immunology; D045744:Cell Line, Tumor; D053938:DNA Fragmentation / Q000187:drug effects; D004273:DNA, Neoplasm / Q000276:immunology; D005656:Fungal Proteins / Q000276:immunology; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000276:immunology / Q000494:pharmacology*; D007135:Immunoglobulin Variable Region / Q000276:immunology / Q000494:pharmacology*; D008297:Male; D008545:Melanoma / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000276:immunology*
chemical_list: D000199:Actins; D058846:Antibodies, Monoclonal, Murine-Derived; D000912:Antibodies, Neoplasm; D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D005656:Fungal Proteins; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C025363:mannoproteins; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C505409:Casp3 protein, mouse; C505526:Casp8 protein, mouse; D053148:Caspase 3; D053181:Caspase 8