Sakata Keiko, Hara Akira, Hirose Yoshinobu, Yamada Yasuhiro, Kuno Toshiya, Katayama Masaki, Yoshida Koujiro, Zheng Qiao, Murakami Akira, Ohigashi Hajime, Ikemoto Kohei, Koshimizu Koichi, Tanaka Takuji, Mori Hideki
Department of Pathology, Gifu University School of Medicine, Gifu, Japan.
Oncology. 2004;66(3):244-52. doi: 10.1159/000078001.
We have previously reported that an antioxidant, auraptene (AUR), isolated from citrus fruit effectively inhibits chemically induced carcinogenesis in digestive tracts, such as the oral cavity, esophagus and large bowel. In this study, we investigated the modifying effects of dietary supplementation with AUR on N,N-diethylnitrosamine (DEN)-initiated hepatocarcinogenesis in male F344 rats in two different experiments to determine whether the compound exerts a cancer-chemopreventive action in other organs.
In the first experiment, animals were fed diets containing AUR at dose levels of 100 and 500 ppm for 7 weeks 1 week before, during, and 1 week after the start of liver carcinogenesis induced by DEN (40 ppm in drinking water for 5 weeks) to predict the modulatory effect on hepatocarcinogenesis. After 7 weeks, the numbers of hepatocellular enzyme-altered foci (EAF; cm(2)) which stained positive for the placental form of glutathione S-transferase (GST-P) and transforming growth factor (TGF)-alpha were determined on immunohistochemically stained sections. In the second experiment conducted to confirm the findings, animals subjected to DEN treatment were fed AUR-containing diets (100 and 500 ppm) during either the initiation stage ('initiation' feeding for 7 weeks) or post-initiation phase ('post-initiation' feeding for 25 weeks) of DEN-induced hepatocarcinogenesis.
In the first experiment, feeding with AUR at both doses during DEN exposure decreased the mean numbers of GST-P-positive and TGF-alpha-positive EAF/cm(2), and the reduction in the number of TGF-alpha-positive EAF by feeding 500 ppm AUR was statistically significant (p < 0.005). In the second experiment, the 'initiation' feeding with 500 ppm AUR significantly inhibited the incidence (33 vs. 83%, p = 0.000511) and multiplicity (0.67 +/- 1.09 vs. 1.96 +/- 1.85, p < 0.005) of liver cell carcinoma. Also, the 'post-initiation' feeding with AUR at both doses significantly reduced the development of hepatocellular carcinoma (100 ppm: incidence, 15%, p = 0.000006; multiplicity: 0.25 +/- 0.64, p < 0.001; 500 ppm: incidence, 11%, p = 0.000002; multiplicity, 0.26 +/- 0.81, p < 0.001). In addition, AUR feeding reduced cell proliferation and the apoptotic index in liver cell neoplasms.
The results suggest that the citrus antioxidant AUR is a potential chemopreventive agent against DEN-induced hepatocarcinogenesis in rats.
我们之前报道过，从柑橘类水果中分离出的抗氧化剂奥瑞烯（AUR）能有效抑制化学诱导的消化道致癌作用，如口腔、食管和大肠。在本研究中，我们在两项不同实验中研究了膳食补充AUR对雄性F344大鼠经N,N -二乙基亚硝胺（DEN）启动的肝癌发生的调节作用，以确定该化合物是否在其他器官发挥癌症化学预防作用。
在第一个实验中，在由DEN（饮用水中40 ppm，持续5周）诱导肝癌发生开始前1周、期间及开始后1周，给动物喂食含100 ppm和500 ppm剂量水平AUR的饲料7周，以预测对肝癌发生的调节作用。7周后，在免疫组织化学染色切片上确定谷胱甘肽S -转移酶（GST - P）胎盘形式和转化生长因子（TGF）-α染色阳性的肝细胞酶改变灶（EAF；cm²）数量。在进行的第二个实验以证实这些发现中，对接受DEN处理的动物，在DEN诱导肝癌发生的起始阶段（“起始”喂养7周）或起始后阶段（“起始后”喂养25周）喂食含AUR的饲料（100 ppm和500 ppm）。
在第一个实验中，在DEN暴露期间喂食两种剂量的AUR均降低了GST - P阳性和TGF -α阳性EAF/cm²的平均数，喂食500 ppm AUR使TGF -α阳性EAF数量的减少具有统计学意义（p < 0.005）。在第二个实验中，用500 ppm AUR进行“起始”喂养显著抑制了肝细胞癌的发生率（33%对83%，p = 0.000511）和多发性（0.67±1.09对1.96±1.85，p < 0.005）。此外，两种剂量的AUR“起始后”喂养均显著降低了肝细胞癌的发生（100 ppm：发生率，15%，p = 0.000006；多发性：0.25±0.64，p < 0.001；500 ppm：发生率，11%，p = 0.000002；多发性，0.26±0.81，p < 0.001）。此外，喂食AUR降低了肝细胞肿瘤中的细胞增殖和凋亡指数。
结果表明，柑橘抗氧化剂AUR是一种潜在的预防大鼠DEN诱导肝癌发生的化学预防剂。
