title: The matrix metalloproteinase inhibitor prinomastat enhances photodynamic therapy responsiveness in a mouse tumor model.
abstract: Photodynamic therapy (PDT) clinical results are promising; however, tumor recurrences can occur and, therefore, methods for improving treatment efficacy are needed. PDT elicits direct tumor cell death and microvascular injury as well as expression of angiogenic, inflammatory, and prosurvival molecules. Preclinical studies combining antiangiogenic drugs or cyclooxygenase-2 inhibitors with PDT show improved treatment responsiveness (A. Ferrario et al., Cancer Res 2000;60:4066-9; A. Ferrario et al., Cancer Res 2002;62:3956-61). In the present study, we evaluated the role of Photofrin-mediated PDT in eliciting expression of matrix metalloproteinases (MMPs) and modulators of MMP activity. We also examined the efficacy of a synthetic MMP inhibitor, Prinomastat, to enhance tumoricidal activity after PDT, using a mouse mammary tumor model. Immunoblot analysis of extracts from PDT-treated tumors demonstrated strong expression of MMPs and extracellular MMP inducer along with a concomitant decrease in expression of tissue inhibitor of metalloproteinase-1. Gelatin zymography and enzyme activity assays performed on protein extracts from treated tumors confirmed the induction of both latent and enzymatically active forms of MMP-9. Immunohistochemical analysis indicated that infiltrating inflammatory cells and endothelial cells were primary sources of MMP-9 expression after PDT, whereas negligible expression was observed in tumor cells. Administration of Prinomastat significantly improved PDT-mediated tumor response (P = 0.02) without affecting normal skin photosensitization. Our results indicate that PDT induces MMPs and that the adjunctive use of an MMP inhibitor can improve PDT tumor responsiveness.
authors.affiliation: Department of Pediatrics, Keck School of Medicine, University of Southern California and the Saban Research Institute, Childrens Hospital Los Angeles, Los Angeles, California, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Ferrario
authors.forename: Christophe F
authors.initials: CF
authors.lastname: Chantrain
authors.forename: Karl
authors.initials: K
authors.lastname: von Tiehl
authors.forename: Sue
authors.initials: S
authors.lastname: Buckley
authors.forename: Natalie
authors.initials: N
authors.lastname: Rucker
authors.forename: David R
authors.initials: DR
authors.lastname: Shalinsky
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimada
authors.forename: Yves A
authors.initials: YA
authors.lastname: DeClerck
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Gomer
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D017323:Dihematoporphyrin Ether / Q000494:pharmacology; D004357:Drug Synergism; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy* / Q000201:enzymology; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000096:biosynthesis / Q000378:metabolism; D051379:Mice; D009930:Organic Chemicals / Q000494:pharmacology*; D010778:Photochemotherapy / Q000379:methods*
chemical_list: D007527:Isoenzymes; D061965:Matrix Metalloproteinase Inhibitors; D009930:Organic Chemicals; C113282:prinomastat; D017323:Dihematoporphyrin Ether; D020782:Matrix Metalloproteinases