title: Treatment with chemopreventive agents, difluoromethylornithine and retinyl acetate, results in altered mammary extracellular matrix.
abstract: The effect of treatment with D-L-2-difluoromethylornithine (DFMO) plus retinyl acetate (RA) on the promotion stage of 1-methyl-1-nitrosourea (MNU)-induced mammary carcinogenesis was evaluated in female Sprague-Dawley rats. Combined treatment was more effective than single agent treatment in decreasing cancer incidence and multiplicity and in prolonging cancer latency. Increased efficacy was associated with reduced morphological complexity of the gland and increased mammary extracellular matrix. Using ovarian hormones to model mitogen stimulation in the mammary gland, DFMO plus RA treatment reduced mammary gland complexity in the absence of an effect on bromodeoxyuridine (BrDU) labeling index measured immunohistochemically. Morphological and biochemical evaluation of these glands revealed increased levels of extracellular matrix in rats treated with chemopreventive agents. Tenascin expression and fibronectin levels were elevated and laminin levels were decreased. The fact that matrix degrading proteinase activity was also increased indicated that tissue remodeling was modulated by these chemopreventive agents. These data provide evidence of alterations in epithelial cell-extracellular matrix interactions that could account in part for the chemopreventive effects of DFMO plus RA.
authors.affiliation: Division of Laboratory Research, AMC Cancer Research Center, Denver, CO 80214, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Schedin
authors.forename: R
authors.initials: R
authors.lastname: Strange
authors.forename: M
authors.initials: M
authors.lastname: Singh
authors.forename: M R
authors.initials: MR
authors.lastname: Kaeck
authors.forename: S C
authors.initials: SC
authors.lastname: Fontaine
authors.forename: H J
authors.initials: HJ
authors.lastname: Thompson
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D004224:Diterpenes; D000518:Eflornithine / Q000494:pharmacology*; D005109:Extracellular Matrix / Q000187:drug effects*; D016326:Extracellular Matrix Proteins / Q000032:analysis; D005260:Female; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D000084562:Retinyl Esters; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D016588:Anticarcinogenic Agents; D004224:Diterpenes; D016326:Extracellular Matrix Proteins; D000084562:Retinyl Esters; D014801:Vitamin A; C009166:retinol acetate; D000518:Eflornithine