title: Adenoviral vector-mediated expression of a gene encoding secreted, EpCAM-targeted carboxylesterase-2 sensitises colon cancer spheroids to CPT-11.
abstract: CPT-11 (irinotecan or 7-ethyl-10[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin) is an anticancer agent in use for the treatment of colon cancer. In order to be fully active, CPT-11 needs to be converted into SN-38 (7-ethyl-10-hydroxycamptothecin) by the enzyme carboxylesterase (CE). In humans, only a minority of CPT-11 is converted to SN-38. To increase the antitumour effect of CPT-11 by gene-directed enzyme prodrug therapy, we constructed a replication-deficient adenoviral vector Ad.C28-sCE2 containing a fusion gene encoding a secreted form of human liver CE2 targeted to the surface antigen epithelial cell adhesion molecule (EpCAM) that is highly expressed on most colon carcinoma cells. By targeting CE2 to EpCAM, the enzyme should accumulate specifically in tumours and leakage into the circulation should be minimised. Ad.C28-sCE2-transduced colon carcinoma cells expressed and secreted active CE that bound specifically to EpCAM-expressing cells. In sections of three-dimensional colon carcinoma spheroids transduced with Ad.C28-sCE2, it was shown that C28-sCE2 was capable of binding untransduced cells. Most importantly, treatment of these spheroids with nontoxic concentrations of CPT-11 resulted in growth inhibition comparable to treatment with SN-38. Therefore, Ad.C28-sCE2 holds promise in gene therapy approaches for the treatment of colon carcinoma.
authors.affiliation: Department of Medical Oncology, Division of Gene Therapy, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands. d.oosterhoff@vumc.nl
authors.forename: D
authors.initials: D
authors.lastname: Oosterhoff
authors.forename: R M
authors.initials: RM
authors.lastname: Overmeer
authors.forename: M
authors.initials: M
authors.lastname: de Graaf
authors.forename: I H
authors.initials: IH
authors.lastname: van der Meulen
authors.forename: G
authors.initials: G
authors.lastname: Giaccone
authors.forename: V W
authors.initials: VW
authors.lastname: van Beusechem
authors.forename: H J
authors.initials: HJ
authors.lastname: Haisma
authors.forename: H M
authors.initials: HM
authors.lastname: Pinedo
authors.forename: W R
authors.initials: WR
authors.lastname: Gerritsen
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000972:Antineoplastic Agents, Phytogenic / Q000633:toxicity; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000633:toxicity*; D043182:Carboxylesterase / Q000235:genetics*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005822:Genetic Vectors; D006801:Humans; D000077146:Irinotecan; D010051:Ovarian Neoplasms
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D043182:Carboxylesterase; D002166:Camptothecin