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In order to evaluate the anti-mutagenic effects of the potential chemoprotective compounds selenium and S-2-(3-Rminopropy1amino)ethylphosphorothioic acid (WR-1065), CHO AA8 cells were exposed to both compounds either individually or in combination prior to irradiation. Mutation frequency fohowing exposure to 8 Gy was evaluated by quantitation of the mutations detected at the hprt locus of these cells. Protection against radiation-induced mutation was observed for both 30 nM sodium selenite or 4 mM WR-1065. In addition, the protection against mutation induction provided by the combination of these agents appeared additive, In contrast, s d u m selenite did not 2 provide protection agdinst radiation toxicity when provided either alone or in conjunction with WR-1065. In order to evaluate the possible mechanisms of the anti-mutagenic effects observed in these cells, glutathione peroxidase (G-) activity was evaluated following exposure to the chemopreventative compounds. The addition of sodium selenite to the culture media resulted in a &fold increase in GPx activity, which was unaltered by the presence of the -1065.Northern analysis of RNA derived from these cells indicated that selenium supplementation resulted in a marginal increase in the d W A for the cytosolic GPx (GSHPx-1) which was insufficient to account for the stimulation of GPx activity observed in cellular extracts. These results suggest that selenium and WR-1065 offer protection via independent mechanisms and that GPx stimulation remains a possible mechanism of the anti-mutagenic effect of selenium. DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thercof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracj, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thercof. Introduction 3A large body of experimental evidence has demonstrated the chemopreventative role of selenium in carcinogenesis. ArLimal studies have indicated that dietary supplementation with low, non-toxic levels of selenium can inhibit tumor formation following insult with a wide variety of carcinogens (1-3). These include chemicals having diverse modes of action, expoawe to Werent qualities of radiation, and oncogenic viruses (1-3). Protection can be observed €or most organ systems w i t h a typical reduction in tumor incidence ranging &om 40%-80%. Numerous in vitro studies have likewise ...

This report details the findings of a single-dose Phase I pharmacokinetic and toxicity study of a food-based formulation of lycopene in healthy adult male subjects. Five dosing groups (n = 5 per group) were sequentially treated with increasing doses of lycopene ranging from 10 to 120 mg. Blood samples were collected for a total of 28 days (672 h) after administration of single doses of lycopene. The mean time (tmax) to reach maximum total lycopene concentration (Cmax) ranged from 15.6 to 32.6 h. The Cmax for total lycopene ranged between 4.03 and 11.27 μg/dl (0.075–0.210 μm). Mean AUC0–96 and elimination half-life for total lycopene ranged from 214 to 655 μg h/dl (3.986–12.201 μmol h/l) and 28.1 and 61.6 h, respectively. The changes observed in lycopene exposure parameters (e.g., Cmax and AUC0–96) were not proportional to increments in dose, with larger increases observed at the lowest end of the dosing range (10–30 mg). Chylomicron lycopene was measured during the first 12 h with the differences observed among the dosing groups not reaching statistical significance. These findings may reflect a process of absorption that is saturable at very low dosing levels or may be explained by the large interindividual variability in attained lycopene concentrations that were observed within each dosing group. Pharmacokinetic parameters for trans- and cis-lycopene isomers were calculated and are reported here. The formulation was well tolerated with minimal side effects, which were mainly of gastrointestinal nature and of very low grade.

T h e m e d i a of representative marnrnalian cell lines were s u p p l e m e n t e d with low levels of selenium in t h e form of sodium selenite in order to investigate t h e effects of selenium on rnammafian cells.Following incubation In 30 nM sodium selenite, these cells were assayed for changes in glutathione peroxidase (GPx) activity. The cells examined included NIH 3T3 mouse fibroblasts, PC12 rat sympathetic precursor cells, cells. AA8 cells w e r e selected to e v a l u a t e whether selenium S u p p l e m e n t a t i o n was radioprotective against 60cobalt gamma irradiation.Protection against radiation-induced mutation was measured by evaluating mutation frequency at the hprt locus. In this assay, pre- Se-dependent glutathione peroxidases (SeGPx) represent a family of related enzymes which are generally believed to constitute a major defense system against toxic peroxides and oxygen free radicals f113. Given the role of SeGPx in anti-oxidant defense, one might speculate that some of the bioprotective effects of selenium, at kast in part, would be due to this enzyme activity. This is generally not believed to be the case as several older studies have indicated that chernoprotective doses of selenium did not result in significant increases in SeGPx activity in experimental animats [I 2,131. In this manuscript, it was examined whether the supplementation of culture media with low levels of sodium selenite would have on effect on GPx activity and report that this activity was stimulated in several mammalian cell lines. A represenlive cell line, CHO AA8 cells, were further examined and shown to be protected from radiation-induced mutation. The irnpiicatioris of this data are discussed reyarding the mechanisms by which selenium may provide its bioprotectivt? role. likely to be by mechanisms independent of effects on GPx activity [12,13,24,25]. The results with CHO AA8 cells indicated that the same dose of selenium that resulted in a better than 4 fold increase in GPx activity significantly protected these cells from radiation-induced mutation. This data cannot distinguish between GPx-dependent vs. -independent mechanisms of protection. Future studies using GPx expression constructs to genetically increase GPx activity independent of selenium status will be required to establish the protective role of this enzyme.Acknowledgement: This work was sapported by Grant ## CN-I33 from the American Cancer Society (to A.M.D.).