Hara Shintaro, Morita Reiko, Ogawa Takashi, Segawa Risa, Takimoto Norifumi, Suzuki Kazuhiko, Hamadate Naobumi, Hayashi Shim-Mo, Odachi Ayano, Ogiwara Isao, Shibusawa Sakae, Yoshida Toshinori, Shibutani Makoto
Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan.
Exp Toxicol Pathol. 2014 Aug;66(5-6):225-34. doi: 10.1016/j.etp.2014.02.002. Epub 2014 Mar 26.
To investigate the protective effect of bilberry extracts (BBE) and enzymatically modified isoquercitrin (EMIQ) on the hepatocarcinogenic process involving oxidative stress responses, we used a two-stage hepatocarcinogenesis model in N-diethylnitrosamine-initiated and piperonyl butoxide (PBO)-promoted rats. We examined the modifying effect of co-administration with BBE or EMIQ on the liver tissue environment including oxidative stress responses, cell proliferation and apoptosis, and phosphatase and tensin homolog (PTEN)/Akt and transforming growth factor (TGF)-β/Smad signalings on the induction mechanism of preneoplastic lesions during early stages of hepatocellular tumor promotion. PBO increased the numbers and area of glutathione S-transferase placental form (GST-P)(+) liver cell foci and the numbers of Ki-67(+) proliferating cells within GST-P(+) foci. Co-administration of BBE or EMIQ suppressed these effects with the reductions of GST-P(+) foci (area) to 48.9-49.4% and Ki-67(+) cells to 55.5-61.4% of the PBO-promoted cases. Neither BBE nor EMIQ decreased microsomal reactive oxygen species induced by PBO. However, only EMIQ suppressed the level of thiobarbituric acid-reactive substances to 78.4% of the PBO-promoted cases. PBO increased the incidences of phospho-PTEN(-) foci, phospho-Akt substrate(+) foci, phospho-Smad3(-) foci and Smad4(-) foci in GST-P(+) foci. Both BBE and EMIQ decreased the incidences of phospho-PTEN(-) foci in GST-P(+) foci to 59.8-72.2% and Smad4(-) foci to 62.4-71.5% of the PBO-promoted cases, and BBE also suppressed the incidence of phospho-Akt substrate(+) foci in GST-P(+) foci to 75.2-75.7% of the PBO-promoted cases. These results suggest that PBO-induced tumor promotion involves facilitation of PTEN/Akt and disruptive TGF-β/Smad signalings without relation to oxidative stress responses, but this promotion was suppressed by co-treatment with BBE or EMIQ through suppression of cell proliferation activity of preneoplastic liver cells.
为了研究越橘提取物（BBE）和酶法改性异槲皮苷（EMIQ）对涉及氧化应激反应的肝癌致癌过程的保护作用，我们在N-二乙基亚硝胺启动和胡椒基丁醚（PBO）促进的大鼠中使用了两阶段肝癌发生模型。我们研究了与BBE或EMIQ共同给药对肝脏组织环境的调节作用，包括氧化应激反应、细胞增殖和凋亡，以及磷酸酶和张力蛋白同源物（PTEN）/Akt和转化生长因子（TGF）-β/Smad信号通路在肝细胞肿瘤促进早期阶段癌前病变诱导机制中的作用。PBO增加了谷胱甘肽S-转移酶胎盘型（GST-P）（+）肝细胞灶的数量和面积以及GST-P（+）灶内Ki-67（+）增殖细胞的数量。与BBE或EMIQ共同给药可抑制这些作用，使GST-P（+）灶（面积）减少至PBO促进组的48.9 - 49.4%，Ki-67（+）细胞减少至PBO促进组的55.5 - 61.4%。BBE和EMIQ均未降低PBO诱导的微粒体活性氧。然而，只有EMIQ将硫代巴比妥酸反应性物质水平抑制至PBO促进组的78.4%。PBO增加了GST-P（+）灶中磷酸化PTEN（-）灶、磷酸化Akt底物（+）灶、磷酸化Smad3（-）灶和Smad4（-）灶的发生率。BBE和EMIQ均将GST-P（+）灶中磷酸化PTEN（-）灶的发生率降低至PBO促进组的59.8 - 72.2%，Smad4（-）灶降低至PBO促进组的62.4 - 71.5%，并且BBE还将GST-P（+）灶中磷酸化Akt底物（+）灶的发生率抑制至PBO促进组的75.2 - 75.7%。这些结果表明，PBO诱导的肿瘤促进涉及PTEN/Akt信号通路的促进和TGF-β/Smad信号通路的破坏，与氧化应激反应无关，但通过抑制癌前肝细胞的增殖活性，与BBE或EMIQ共同处理可抑制这种促进作用。
