Anti-tumor effect against human cancer xenografts by a fully human monoclonal antibody to a variant 8-epitope of CD44R1 expressed on cancer stem cells

PLoS One. 2012;7(1):e29728. doi: 10.1371/journal.pone.0029728. Epub 2012 Jan 17.


Background: CD44 is a major cellular receptor for hyaluronic acids. The stem structure of CD44 encoded by ten normal exons can be enlarged by ten variant exons (v1-v10) by alternative splicing. We have succeeded in preparing MV5 fully human IgM and its class-switched GV5 IgG monoclonal antibody (mAb) recognizing the extracellular domain of a CD44R1 isoform that contains the inserted region coded by variant (v8, v9 and v10) exons and is expressed on the surface of various human epithelial cancer cells.

Methods and principal findings: We demonstrated the growth inhibition of human cancer xenografts by a GV5 IgG mAb reshaped from an MV5 IgM. The epitope recognized by MV5 and GV5 was identified to a v8-coding region by the analysis of mAb binding to various recombinant CD44 proteins by enzyme-linked immunosorbent assay. GV5 showed preferential reactivity against various malignant human cells versus normal human cells assessed by flow cytometry and immunohistological analysis. When ME180 human uterine cervix carcinoma cells were subcutaneously inoculated to athymic mice with GV5, significant inhibition of tumor formation was observed. Furthermore, intraperitoneal injections of GV5markedly inhibited the growth of visible established tumors from HSC-3 human larynx carcinoma cells that had been subcutaneously transplanted one week before the first treatment with GV5. From in vitro experiments, antibody-dependent cellular cytotoxicity and internalization of CD44R1 seemed to be possible mechanisms for in vivo anti-tumor activity by GV5.

Conclusions: CD44R1 is an excellent molecular target for mAb therapy of cancer, possibly superior to molecules targeted by existing therapeutic mAb, such as Trastuzumab and Cetuximab recognizing human epidermal growth factor receptor family.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal / pharmacology*
  • Antibody Specificity / immunology
  • Antibody-Dependent Cell Cytotoxicity / drug effects
  • Antibody-Dependent Cell Cytotoxicity / immunology
  • Antineoplastic Agents / immunology
  • Antineoplastic Agents / pharmacology*
  • Cell Line, Tumor
  • Epitopes / genetics
  • Epitopes / immunology
  • Epitopes / metabolism
  • Female
  • Flow Cytometry
  • Genetic Variation
  • HCT116 Cells
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Hyaluronan Receptors / genetics
  • Hyaluronan Receptors / immunology
  • Hyaluronan Receptors / metabolism*
  • Immunohistochemistry
  • Lymphocytes / drug effects
  • Lymphocytes / immunology
  • Mice
  • Mice, Nude
  • Neoplasms / drug therapy*
  • Neoplasms / immunology
  • Neoplasms / metabolism
  • Neoplastic Stem Cells / drug effects*
  • Neoplastic Stem Cells / immunology
  • Neoplastic Stem Cells / metabolism
  • Protein Isoforms / genetics
  • Protein Isoforms / immunology
  • Protein Isoforms / metabolism
  • Rats
  • Rats, Inbred F344
  • Xenograft Model Antitumor Assays


  • Antibodies, Monoclonal
  • Antineoplastic Agents
  • Epitopes
  • Hyaluronan Receptors
  • Protein Isoforms