Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sumach leaf, Aleppo gall, Tara pod and commercial tannic acids (TAs) were tested topically for their ability to inhibit the biochemical and biological effects of 12-0-tetradecanoylphorbol-13-acetate (TPA) in mouse epidermis in vivo. These TAs all inhibit to various degrees ornithine decarboxylase (ODC) induction, hydroperoxide (HPx) production and the sequential stimulation of RNA, protein and DNA synthesis linked to TPA promotion. When applied before each promotion treatment, these TAs all inhibit complete tumor promotion by TPA. Sumach leaf TA is the most effective. TAs applied 24h after TPA inhibit HPx production but not tumor promotion, since ODC activity and DNA synthesis have already been stimulated. However, these TA post-treatments enhance the antioxidant and antitumor-promoting effects of TA pretreatments. TAs inhibit the 2nd rather than the 1st stage of tumor promotion. Plant TAs, therefore, may be valuable against tumor propagation but their efficacy may vary considerably depending on their origin.
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PMID:Antitumor-promoting effects of gallotannins extracted from various sources in mouse skin in vivo. 768 39

We recently showed that Tarapod tannic acid (TA), a hydrolyzable tannin extracted from the pods of the Tara tree (Caesalpinia spinosa), was more effective than other tannins tested at inhibiting ultraviolet-B (UV-B)-stimulated hydrogen peroxide activity (an indirect measure of free radicals) in the skin of hairless mice. We also found that Tarapod TA inhibited UV-B-induced ornithine decarboxylase activity and UV-B-stimulated DNA synthesis, two biochemical markers linked to the skin tumor-promoting ability of this physical carcinogen. For this reason, we examined the effect of topical application, force feeding (gavage), and intraperitoneal injections of Tarapod TA on mouse skin chronically treated with UV-B light. Mice were initiated by a single topical application of 7,12-dimethylbenz[a]anthracene (50 nmol) and promoted by two weekly treatments with UV-B light (250 mJ/cm2) for 25 weeks. Topical application of Tarapod TA, 20 minutes before irradiation, resulted in a dose-dependent inhibition of tumor incidence (number of mice with tumors) and tumor yield (number of tumors/mouse), with 8 mg of TA inhibiting tumor yield by 70% at Week 25. Intraperitoneal injections of low doses (10 mg/kg mouse body wt), but not of high doses (25 mg/kg body wt), of TA afforded protection against UV-B-induced papillomas. However, the protection by intraperitoneal injection was lower than that observed by topical application: 10 mg/kg body wt of TA reduced tumor yield by 55%. The force feeding of 10 mg of Tarapod TA before irradiation failed to significantly inhibit the yield of tumors at the end of the experiment but delayed tumor appearance by six weeks. These results suggest that plant tannins administered topically or injected intraperitoneally reduce the tumor-promoting effects of UV-B radiation and thus could be useful photoprotectants.
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PMID:Tannins protect against skin tumor promotion induced by ultraviolet-B radiation in hairless mice. 1096 22