Japanese Journal of Clinical Oncology Advance Access originally published online on April 12, 2006
Japanese Journal of Clinical Oncology 2006 36(4):207-211; doi:10.1093/jjco/hyl004
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© 2006 Foundation for Promotion of Cancer Research
Doxorubicin-Conjugated Anti-Midkine Monoclonal Antibody as a Potential Anti-Tumor Drug
1 Department of Biochemistry, 2 Department of Plastic Surgery and 3 Division of Disease Models, Center for Neural Disease and Cancer, Nagoya University Graduate School of Medicine, Nagoya, 4 Meiji Milk Co Ltd, Odawara, Kanagawa, 5 Cell Signals Inc., Yokohama and 6 Peptide Institute, Minoh, Osaka, Japan
For reprints and all correspondence: Hisako Muramatsu, Department of Biochemistry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. E-mail: hmurama{at}med.nagoya-u.ac.jp
Received November 24, 2003; accepted December 28, 2005
Background: Midkine is a heparin-binding growth factor preferentially expressed in tumor cells. The present study was performed to utilize anti-midkine antibody for tumor therapy.
Methods: A monoclonal antibody to midkine was raised by immunizing mice deficient in the midkine gene. The binding site of the antibody was studied by using N-terminal half and C-terminal half of midkine, both of which were chemically synthesized. Doxorubicin (DOX)-conjugate of the antibody was produced by chemical conjugation. The effects of the antibody and the conjugate on cell growth were examined using a midkine-secreting tumor cell, i.e. human hepatocellular carcinoma cell (HepG2).
Results: The monoclonal antibody bound to the N-terminal half of midkine. The antibody did not inhibit the growth of HepG2 cells probably because the active domain of midkine is in the C-terminal half. We produced the antibody conjugated with DOX with the hope that the conjugate would be internalized accompanied with midkine. Indeed, the antibody-DOX conjugate significantly inhibited the growth of HepG2 cells compared with DOX-conjugated control IgG.
Conclusion: The result raises the possibility of using anti-midkine antibody conjugated with DOX for cancer therapy.
Key Words: antibody monoclonal cancer growth substances immunotoxins