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  • 1
    ISSN: 0730-2312
    Keywords: chemoprevention ; H-ras ; PCNA ; rat ; retinoid ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Mammary tumors were induced in 48-52-day-old female Sprague-Dawley rats in metestrus or diestrus with a single jugular injection of MNU (50 mg/kg). Control rats received the saline vehicle (Group 4 n = 9). Rats were fed 4% Teklad diet containing either 0 (Group 3, n = 20) or 782 mg 4-HPR/kg diet. 4-HPR supplementation was initiated either 1 week prior to (Group 1, n = 14) or 4 weeks following MNU administration (Group 2, n = 19). Neither body weight nor food intake differed significantly between treatment groups. Feeding of 4-HPR 1 week prior to tumor induction reduced the number of tumors (0.8±.2) when compared to MNU control rats (2.1±.4). Immunohistochemical staining of mammary tumor sections for PCNA was quantitated by microdensitometry and expressed as an HSCORE. No differences in HSCORE were observed between tumor groups although the percentage of nuclear area occupied by intermediate and darkly stained nuclei was reduced in the late 4-HPR group. GC→AT transitions in codon 12 of the H-ras gene were detected in 50% (12/24) of MNU control tumors, 60% (6/10) of early 4-HPR tumors, and 38% (6/16) of late 4-HPR tumors. Mutation rates did not differ significantly between groups. 4-HPR appears to be a more effective chemopreventive when fed during the initiation period. J. Cell. Biochem. Suppl. 27:92-99. © 1998 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0730-2312
    Keywords: cancer chemopreventive agents ; drug development ; retinoids ; DFMO ; NSAIDs ; oltipraz ; Phase I clinical trials ; Phase II clinical trials ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Clinical chemoprevention trials of more than 30 agents and agent combinations are now in progress or being planned. The most advanced agents are well known and are in large Phase III chemoprevention intervention trials or epidemiological studies. These drugs include several retinoids [e.g., retinol, retinyl palmitate, all-trans-retinoic acid, and 13-cis-retinoic acid], calcium, βcarotene, vitamin E, tamoxifen, and finasteride. Other newer agents are currently being evaluated in or being considered for Phase II and early Phase III chemoprevention trials. Prominent in this group are all-trans-N-(4-hydroxy phenyl)retinamide (4-HPR) (alone and in combination with tamoxifen), 2-difluoromethylornithine (DFMO), nonsteroidal antiinflammatory drugs (aspirin, piroxicam, sulindac), oltipraz, and dehydroepiandrostenedione (DHEA).A third group is new agents showing chemopreventive activity in animal models, epidemiological studies, or in pilot clinical intervention studies. They are now in preclinical toxicology testing or Phase I safety and pharmacokinetics trials preparatory to chemoprevention efficacy trials. These agents include S-allyl-l-cysteine, curcumin, DHEA analog 8354 (fluasterone), genistein, ibuprofen, indole-3-carbinol, perillyl alcohol, phenethyl isothiocyanate, 9-cis-retinoic acid, sulindac sulfone, tea extracts, ursodiol, vitamin D analogs, and p-xylyl selenocyanate. A new generation of agents and agent combinations will soon enter clinical chemoprevention studies based primarily on promising chemopreventive activity in animal models and in mechanistic studies. Among these agents are more efficacious analogs of known chemopreventive drugs including novel carotenoids (e.g., α-carotene and lutein). Also included are safer analogs which retain the chemopreventive efficacy of the parent drug such as vitamin D3 analogs. Other agents of high interest are aromatase inhibitors (e.g., (+)-vorozole), and protease inhibitors (e.g., Bowman-Birk soybean trypsin inhibitor). Combinations are also being considered, such as vitamin E with l-selenomethionine. Analysis of signal transduction pathways is beginning to yield classes of potentially active and selective chemopreventive drugs. Examples are ras isoprenylation and epidermal growth factor receptor inhibitors. 1997 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Type of Medium: Electronic Resource
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