Intrahepatic cholangiocarcinoma (ICC), a malignant tumor derived from the intrahepatic bile duct epithelium, has a poor prognosis and is refractory to conventional chemotherapy and radiation therapy. Thus, there is an urgent need to develop new effective therapeutic strategies for this disease. We previously found that L1 cell adhesion molecule (L1CAM) plays an important role in tumor progression of ICC, and we generated a murine mAb, A10-A3 (IgG1), that binds to the Ig1 domain of L1CAM. In the present study, we further characterized A10-A3, constructed a chimeric A10-A3 antibody (cA10-A3) containing the constant regions of human IgG1, and evaluated the therapeutic potential in a human ICC xenograft nude mice model. The affinities (K D) of A10-A3 and cA10-A3 for soluble L1CAM were 1.8 nM and 1.9 nM, respectively, as determined by competition ELISA. A10-A3 inhibited L1CAM homophilic binding and was slowly internalized into the tumor cells, but it did not significantly inhibit proliferation of ICC cells in vitro. cA10-A3 mediated antibody-dependent cell-mediated cytotoxicity in vitro and displayed anti-tumor activity in the ICC animal model. These results suggest that the humanized A10-A3 antibody may have potential as an anticancer agent for the treatment of ICC.
Animals ; Antibodies, Monoclonal/genetics/*immunology ; Antibody-Dependent Cell Cytotoxicity ; Bile Ducts, Intrahepatic/drug effects/immunology/pathology ; CHO Cells ; Cell Adhesion/drug effects ; Cell Proliferation/drug effects ; Cholangiocarcinoma/*drug therapy/immunology/pathology ; Cricetinae ; Disease Models, Animal ; Endocytosis/drug effects ; Humans ; Immunoglobulin G/genetics/*immunology ; Liver Neoplasms/*drug therapy/immunology/pathology ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Neural Cell Adhesion Molecule L1/genetics/*immunology/metabolism ; Protein Binding ; Protein Structure, Tertiary ; Recombinant Fusion Proteins/immunology/metabolism/*therapeutic use

Cholangiocarcinoma (CC) is a chemoresistant intrahepatic bile duct carcinoma with a poor prognosis. The aims of this study were to identify molecular pathways that enhance sesquiterpene lactone parthenolide (PTL)-induced anticancer effects on CC cells. The effects of PTL on apoptosis and hemoxygenase-1 (HO-1) induction were examined in CC cell lines. The enhancement of PTL-mediated apoptosis by modulation of HO-1 expression and the mechanisms involved were also examined in an in vitro cell system. Low PTL concentrations (5 to 10 micrometer) led to Nrf2-dependent HO-1 induction, which attenuated the apoptogenic effect of PTL in Choi-CK and SCK cells. PTL-mediated apoptosis was enhanced by the protein kinase C-alpha inhibitor Ro317549 (Ro) through inhibition of expression and nuclear translocation of Nrf2, resulting in blockage of HO-1 expression. Finally, HO-1 silencing resulted in enhancement of apoptotic cell death in CC cells. The combination of PTL and Ro efficiently improved tumor growth inhibition compared to treatment with either agent alone in an in vivo subcutaneous tumor model. In conclusion, the modulation of HO-1 expression substantially improved the anticancer effect of PTL. The combination of PTL and Ro could prove to be a valuable chemotherapeutic strategy for CC.
Active Transport, Cell Nucleus/drug effects ; Antineoplastic Agents/chemistry/*pharmacology ; Apoptosis/drug effects/genetics ; Cell Line, Tumor ; Cell Nucleus/*metabolism ; Cholangiocarcinoma/drug therapy/*metabolism/pathology ; Drug Resistance, Neoplasm/drug effects/genetics ; Enzyme Activation ; Enzyme Inhibitors/pharmacology ; Heme Oxygenase-1/genetics/*metabolism ; Humans ; Lactones/chemistry ; NF-E2-Related Factor 2/genetics/*metabolism ; Protein Kinase C-alpha/antagonists & inhibitors ; RNA, Small Interfering/genetics ; Sesquiterpenes/chemistry/*pharmacology ; Signal Transduction/drug effects