Sensitization of Human Breast Cancer Cells to Cyclophosphamide and Ifosfamide by Transfer of a Liver Cytochrome P450 Gene

摘要: Abstract The cancer chemotherapeutic agent cyclophosphamide (CPA) and its isomer ifosfamide (IFA) are alkylating prodrugs that require metabolism by liver cytochrome P450 (P450) enzymes for antitumor activity. therapeutic effectiveness of these oxazaphosphorines is limited the hematopoietic, renal, cardiac toxicity accompanies systemic distribution liver-derived activated drug metabolites. Transfer a gene, CYP2B1, into human breast MCF-7 cells presently shown to greatly sensitize oxazaphosphorine as consequence acquired capacity intratumoral CPA IFA activation. Thus, were highly cytotoxic following stable transfection CYP2B1 but exhibited no parental tumor or β-galactosidase-expressing transfectant. This cytotoxicity could be appreciably blocked inhibitor metyrapone. Cell cycle analysis revealed arrested CYP2B1-expressing cells, not CYP2B1-negative at G2-M phase. A strong bystander effect does direct cell-cell contact was mediated on non-CYP2B1 cells. Intratumoral expression conferred distinct advantage when treating tumors grown in nude mice with CPA, 15–20-fold greater vivo cytotoxicity, determined excision/colony formation assay, substantially enhanced activity, monitored growth delay, compared control tumors. These effects obtained without any apparent increase host toxicity. To evaluate extent which CPA/P450 gene therapy strategy may generally applicable other cell types, replication-defective recombinant adenovirus carrying driven cytomegalovirus (CMV) promoter Ad.CMV-2B1 constructed used infect panel lines. infection rendered each lines sensitive substantial chemosensitization seen multiplicities low 10. prodrug activation system thus serve useful paradigm further development novel strategies utilize susceptibility genes significantly potentiate activity conventional agents.