Targeting of human squamous carcinomas by SPA470-doxorubicin immunoconjugates.

Abstract

In a quest to identify a favorable target for head and neck cancers and squamous cell carcinoma, we sought to determine if Hsp47/CBP2 could be used as a target and whether the expression of this target was influenced by hypoxia. Moreover, we determined if doxorubicin (DOX) immunoconjugates directed against Hsp47/CBP2 that linked monoclonal antibodies (MAbs) to the 13-keto position of the drug possessed high cytotoxic drug activity and antibody-directed killing of antigen bearing tumor target cells. Experiments were performed using established cell lines of human oral squamous carcinoma cells (SCCs) (SCC-4, -9, -15 and -25) obtained from American Type Culture Collection (ATCC) (Manassas, VA). In addition, the UMB2 cell line is a spontaneous mutant of SCC-9 that does not express Hsp47/CBP2 was also used. Synthesis of the immunoconjugates was accomplished by thiolating the MAbs with 2 IT and reacting the MAbs with the DOX-hydrazone. The binding of MAb-DOX conjugates to SCC cells was determined by indirect immunofluorescence and analyzed using a Becton Dickinson FACS scan with Cell Quest software. Comparison of the cytotoxicity of DOX, MAb-DOX conjugates and MAb+DOX were determined using a limited dilution assay and colony survival assays during normoxia and hypoxia. These studies revealed that SCC cells treated with the SPA470-DOX conjugate for 2 h retained the original binding activity for targeted SCC cells and was significantly more potent that unconjugated DOX, DOX-hydrazone or equivalent MAb protein+DOX. Also, SPA47-DOX produced equal to and at lower concentrations greater cell killing than equivalent dose of free DOX. During hypoxia cells treated with SPA470-DOX demonstrated a small increase in colony survival and a diminishment in cytotoxicity. SPA470-DOX conjugates target SCC cells that express Hsp47/CBP2. The demonstration that SPA470-DOX is effective during hypoxia or conditions that mimic hypoxia presumes the further utility of SPA470-DOX in treating head and neck cancers.

• Authors: C Hebert, K Norris, J J Sauk
• Journal: Journal of drug targeting (J Drug Target) Vol. 11 Issue 2 Pg. 101-7 (Feb 2003) ISSN: 1061-186X [Print] England
• PMID: 12881196 (Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Antibodies, Monoclonal
• Antineoplastic Agents
• HSP47 Heat-Shock Proteins
• Heat-Shock Proteins
• Immunoconjugates
• SERPINH1 protein, human
• Doxorubicin

Topics

• Antibodies, Monoclonal (administration & dosage, chemistry, pharmacology)
• Antineoplastic Agents (administration & dosage, chemistry, pharmacology)
• Carcinoma, Squamous Cell (pathology)
• Cell Hypoxia
• Cell Survival (drug effects)
• Dose-Response Relationship, Drug
• Doxorubicin (administration & dosage, chemistry, pharmacology)
• Fluorescent Antibody Technique, Indirect
• HSP47 Heat-Shock Proteins
• Head and Neck Neoplasms (pathology)
• Heat-Shock Proteins (genetics, metabolism)
• Humans
• Immunoconjugates (administration & dosage, pharmacology)
• Tumor Cells, Cultured