title: Cox-2 gene expression in chemically induced skin papillomas cannot predict subsequent tumor fate.
abstract: Elevated cyclooxygenase-2 (COX-2) expression is observed in a variety of premalignant neoplastic tissues, suggesting COX-2 expression might serve as a potential indicator of subsequent tumor development. However, it has not been possible to compare the relationship between Cox-2 gene expression in premalignant lesions and their subsequent fate, because conventional studies require tissue destruction for analysis of gene expression. To monitor COX-2 expression non-invasively during tumor development, we created a Cox-2 luciferase knock-in mouse, Cox-2(luc), in which the firefly luciferase coding region replaces the Cox-2 coding region. Luciferase activity was non-invasively, quantitatively and repeatedly monitored in Cox-2(luc/+) mice subjected to DMBA/TPA multistage skin tumor induction. Luciferase activity is significantly higher in all papillomas than in surrounding skin. However, the magnitude of Cox-2 promoter-driven luciferase activity in small papillomas cannot predict subsequent papilloma regression or growth. Elevated Cox-2 promoter-driven luciferase signal can be detected when papillomas first become visible, but not before this time.
authors.affiliation: Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.
authors.forename: Tomo-o
authors.initials: TO
authors.lastname: Ishikawa
authors.forename: Naveen K
authors.initials: NK
authors.lastname: Jain
authors.forename: Harvey R
authors.initials: HR
authors.lastname: Herschman
mesh_terms: D000818:Animals; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D055879:Gene Knock-In Techniques; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D010212:Papilloma / Q000139:chemically induced / Q000235:genetics / Q000473:pathology; D011401:Promoter Regions, Genetic; D012878:Skin Neoplasms / Q000139:chemically induced / Q000235:genetics / Q000473:pathology
chemical_list: D008156:Luciferases; D051546:Cyclooxygenase 2