Inoh Kazuhiko, Muramatsu Hisako, Torii Shuhei, Ikematsu Shinya, Oda Munehiro, Kumai Hideshi, Sakuma Sadatoshi, Inui Tatsuya, Kimura Terutoshi, Muramatsu Takashi
Department of Biochemistry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
Jpn J Clin Oncol. 2006 Apr;36(4):207-11. doi: 10.1093/jjco/hyl004. Epub 2006 Apr 12.
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.
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).
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.
The result raises the possibility of using anti-midkine antibody conjugated with DOX for cancer therapy.
中期因子是一种优先在肿瘤细胞中表达的肝素结合生长因子。本研究旨在利用抗中期因子抗体进行肿瘤治疗。
通过免疫中期因子基因缺陷的小鼠制备抗中期因子单克隆抗体。使用化学合成的中期因子N端半段和C端半段研究抗体的结合位点。通过化学偶联制备抗体与阿霉素（DOX）的偶联物。使用分泌中期因子的肿瘤细胞，即人肝癌细胞（HepG2），检测抗体和偶联物对细胞生长的影响。
单克隆抗体与中期因子的N端半段结合。该抗体未抑制HepG2细胞的生长，可能是因为中期因子的活性结构域在C端半段。我们制备了与DOX偶联的抗体，希望该偶联物能伴随中期因子被内化。事实上，与DOX偶联的对照IgG相比，抗体-DOX偶联物显著抑制了HepG2细胞的生长。
该结果增加了使用与DOX偶联的抗中期因子抗体进行癌症治疗的可能性。
