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

• Published in: The Journal of biological chemistry Vol. 287; no. 18; pp. 14912 - 14922
• Main Authors: Arruda, Denise C., Santos, Luana C.P., Melo, Filipe M., Pereira, Felipe V., Figueiredo, Carlos R., Matsuo, Alisson L., Mortara, Renato A., Juliano, Maria A., Rodrigues, Elaine G., Dobroff, Andrey S., Polonelli, Luciano, Travassos, Luiz R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 27-04-2012; American Society for Biochemistry and Molecular Biology
• Subjects: Actin; Actins - immunology; Animals; Antibodies, Monoclonal, Murine-Derived - immunology; Antibodies, Monoclonal, Murine-Derived - pharmacology; Antibodies, Neoplasm - pharmacology; Antineoplastic Agents - immunology; Antineoplastic Agents - pharmacology; Apoptosis; Apoptosis - drug effects; Cancer Therapy; Candida albicans - immunology; Caspase 3 - immunology; Caspase 8 - immunology; Cell Biology; Cell Death; Cell Line, Tumor; DNA Fragmentation - drug effects; DNA, Neoplasm - immunology; Fungal Proteins - immunology; Humans; Immunoglobulin CDR; Immunoglobulin Heavy Chains - immunology; Immunoglobulin Heavy Chains - pharmacology; Immunoglobulin Variable Region - immunology; Immunoglobulin Variable Region - pharmacology; Male; Melanoma - immunology; Melanoma - pathology; Melanoma - prevention & control; Membrane Glycoproteins - immunology; Metastatic Melanoma; Mice; Neoplasm Metastasis; Neoplasm Proteins - immunology; Peptides; Tumor Cells; β-Actin; Cancer Therapy; Immunoglobulin CDR; Tumor Cells; Peptides; Actin; Cell Death; Metastatic Melanoma; Apoptosis; β-Actin
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.322362

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.
Background: Immunoglobulin complementarity-determining region (CDR) peptides frequently display antitumor activities.
Results: Monoclonal antibody C7 CDR-H2 binds to β-actin and induces polymerization, F-actin stabilization, and tumor cell death.
Conclusion: Alterations of actin dynamics trigger reactive oxygen species and tumor cell apoptosis.
Significance: The in vitro apoptotic effect and in vivo antimetastatic activity of peptide C7H2 makes it a candidate to be developed as an anticancer drug.