Takumi Shota, Ikema Satoshi, Hanyu Tamami, Shima Yusuke, Kurimoto Takashi, Shiozaki Kazuhiro, Sugiyama Yasumasa, Park Ho-Dong, Ando Seiichi, Furukawa Tatsuhiko, Komatsu Masaharu
Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, Tokyo 105-8461, Japan.
Division of Food and Chemical Biology, Faculty of Fisheries, Kagoshima University, Kagoshima 890-0056, Japan.
Environ Toxicol Pharmacol. 2015 Mar;39(2):974-81. doi: 10.1016/j.etap.2015.02.021. Epub 2015 Mar 7.
Microcystin-LR, which is an inhibitor of serine/threonine protein phosphatase (PP)1 and PP2A, induces liver injury by its selective uptake system into the hepatocyte. It is also thought that microcystin-LR induces reactive oxygen species (ROS). We tried to establish the chemical prevention of microcystin-LR poisoning. We investigated the effect of grapefruit flavanone glycoside naringin on cytotoxicity of microcystin-LR using human hepatocyte uptake transporter OATP1B3-expressing HEK293-OATP1B3 cells. We found cytotoxicity of microcystin-LR was attenuated by naringin in a dose dependent manner. The inhibition magnitude of total cellular serine/threonine protein phosphatase activity induced by microcystin-LR was suppressed by naringin. In addition, uptake of microcystin-LR into HEK293-OATP1B3 cells was inhibited by naringin. Furthermore, microcystin-LR induced phosphorylation of p53 was inhibited by naringin. Regardless of the difference in the exposure pattern of pre-processing and post-processing of naringin, the toxicity of microcystin-LR was comparable. These results suggested that naringin is promising remedy as well as preventive medicine for liver damage with microcystin-LR. In addition, involvement of ROS production after exposure to the sublethal concentrations of microcystin-LR in the onset of cytotoxicity was negligible. Therefore, inhibition of microcystin-LR uptake and the pathway other than ROS production would be involved in the effect of naringin on the attenuation of microcystin-LR toxicity.
微囊藻毒素-LR是丝氨酸/苏氨酸蛋白磷酸酶（PP）1和PP2A的抑制剂，通过其进入肝细胞的选择性摄取系统诱导肝损伤。也有人认为微囊藻毒素-LR会诱导活性氧（ROS）产生。我们试图建立对微囊藻毒素-LR中毒的化学预防方法。我们使用表达人肝细胞摄取转运体OATP1B3的HEK293-OATP1B3细胞，研究了葡萄柚黄酮糖苷柚皮苷对微囊藻毒素-LR细胞毒性的影响。我们发现柚皮苷以剂量依赖的方式减弱了微囊藻毒素-LR的细胞毒性。柚皮苷抑制了微囊藻毒素-LR诱导的总细胞丝氨酸/苏氨酸蛋白磷酸酶活性的抑制程度。此外，柚皮苷抑制了微囊藻毒素-LR进入HEK293-OATP1B3细胞。此外，柚皮苷抑制了微囊藻毒素-LR诱导的p53磷酸化。无论柚皮苷预处理和后处理的暴露模式有何差异，微囊藻毒素-LR的毒性都是相当的。这些结果表明，柚皮苷有望成为治疗和预防微囊藻毒素-LR所致肝损伤的药物。此外，在细胞毒性发生过程中，暴露于亚致死浓度的微囊藻毒素-LR后ROS产生的参与程度可忽略不计。因此，柚皮苷对微囊藻毒素-LR毒性减弱的作用可能涉及抑制微囊藻毒素-LR的摄取以及ROS产生以外的途径。
