Bhimani R S, Troll W, Grunberger D, Frenkel K
Department of Environmental Medicine, New York University Medical Center, New York 10016-6451.
Cancer Res. 1993 Oct 1;53(19):4528-33.
12-O-Tetradecanoylphorbol-13-acetate (TPA)-mediated oxidative stress in HeLa cells and its inhibition were studied by fluorometric measurement of H2O2 and by 3H-postlabeling of the oxidized bases 8-hydroxyl-2'-deoxyguanosine (8-OHdG) and 5-hydroxymethyl-2'-deoxyuridine (HMdU). TPA treatment (10 fmol/cell) caused approximately 7-fold increase in H2O2 levels (0.1 nmol TPA/ml), and 5-10-fold increase in 8-OHdG and HMdU (10 nmol TPA/ml). Naturally occurring compounds [caffeic acid phenethyl ester (CAPE), (-).epigallocatechin gallate (EGCG), penta-O-galloyl-beta-D-glucose (PGG) and sarcophytol A (Sarp A)] and the anticancer drug tamoxifen (TAM) were tested as potential chemopreventive agents. These agents dose-dependently inhibited TPA-induced H2O2, 8-OHdG and HMdU. The doses required for a 50% decrease in H2O2 were approximately 2.5 microM for TAM; 5 microM for CAPE, EGCG and PGG; and 75 microM for Sarp A. TAM and PGG (10 microM), EGCG (25 microM), and CAPE (50 microM) abolished TPA-mediated H2O2 production, even below the normal cellular levels. TAM (2.5-20 microM) decreased TPA-mediated HMdU and 8-OHdG formation 2-29 times. Maximum inhibition occurred at 20 microM TAM, which caused an approximately 95% decline in HMdU and 8-OHdG. CAPE was effective at 0.5-50 microM. CAPE (25 microM) decreased 8-OHdG 95%, and HMdU 58%, while Sarp A (250 microM) reduced 8-OHdG by 93% and HMdU by 78%. EGCG (1-25 microM) and PGG (1-10 microM) inhibited of 8-OHdG and HMdU dose-dependently. However, higher doses (50 and 100 microM) decreased the efficacy of that inhibition. Of those agents tested, TAM appears to be the most and Sarp A the least effective. Our results point to these 5 compounds as being potential chemopreventive agents, which at very low doses decrease the tumor promoter-mediated oxidative processes.
通过荧光法测定过氧化氢以及对氧化碱基8-羟基-2'-脱氧鸟苷（8-OHdG）和5-羟甲基-2'-脱氧尿苷（HMdU）进行³H后标记，研究了12-O-十四烷酰佛波醇-13-乙酸酯（TPA）介导的HeLa细胞氧化应激及其抑制作用。TPA处理（10 fmol/细胞）使过氧化氢水平（0.1 nmol TPA/ml）增加约7倍，使8-OHdG和HMdU（10 nmol TPA/ml）增加5至10倍。对天然存在的化合物[咖啡酸苯乙酯（CAPE）、（-）-表没食子儿茶素没食子酸酯（EGCG）、五-O-没食子酰-β-D-葡萄糖（PGG）和肉珊瑚醇A（Sarp A）]以及抗癌药物他莫昔芬（TAM）作为潜在化学预防剂进行了测试。这些试剂剂量依赖性地抑制TPA诱导的过氧化氢、8-OHdG和HMdU。使过氧化氢水平降低50%所需的剂量，TAM约为2.5 μM；CAPE、EGCG和PGG为5 μM；Sarp A为75 μM。TAM和PGG（10 μM）、EGCG（25 μM）和CAPE（50 μM）消除了TPA介导的过氧化氢产生，甚至低于正常细胞水平。TAM（2.5 - 20 μM）使TPA介导的HMdU和8-OHdG形成减少2至29倍。在20 μM TAM时出现最大抑制，导致HMdU和8-OHdG下降约95%。CAPE在0.5 - 50 μM有效。CAPE（25 μM）使8-OHdG降低95%，使HMdU降低58%，而Sarp A（250 μM）使8-OHdG降低93%，使HMdU降低78%。EGCG（1 - 25 μM）和PGG（1 - 10 μM）剂量依赖性地抑制8-OHdG和HMdU。然而，更高剂量（50和100 μM）会降低这种抑制的效果。在这些测试的试剂中，TAM似乎最有效，而Sarp A最无效。我们的结果表明这5种化合物是潜在的化学预防剂，它们在非常低的剂量下就能减少肿瘤启动子介导的氧化过程。
