State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, Nanjing, People's Republic of China.
Toxicol Lett. 2012 Apr 5;210(1):78-86. doi: 10.1016/j.toxlet.2012.01.019. Epub 2012 Jan 31.
A tightly regulated catabolic process named autophagy involves the degradation of intracellular components via lysosomes. Here we investigate the antitumor effect of E Platinum, a newly synthesized derivative of oxaliplatin, in vivo and in vitro. E Platinum exhibits growth inhibition of various tumor cells in a dose-dependent manner, but the mechanism underlying it is unclear. Based on theory introducing autophagy, we preliminarily investigate whether autophagy could contribute to the antitumor activity of E Platinum. Our results showed that autophagy induced by 12.5 μM E Platinum in gastric carcinoma BGC-823 cells was significantly characterized by the FITC-fluorescent microtubule associated protein 1 light chain 3 (MAP-LC3), lysosomal-rich/acidic compartments visualized with Lysotracker red (LTR-red) and an accumulation of numerous large autophagic vesicles within the cytoplasm, but not in the control cells. Meanwhile treatment of cells with 12.5 μM E Platinum resulted in conversion of water soluble LC3 (LC3-I) to lipidated and autophagosome-associated form (LC3-II) as well as increasing expression of autophagy protein Beclin 1. Activation of predominant lysosomal aspartic protease, LAMP-1 and cathepsin D, was demonstrated. Moreover, RNA interference targeting Beclin 1, inhibition of autophagy by 3-methyladenine (3-MA) and chloroquine significantly suppressed the above process as well as the BGC-823 cells growth inhibition triggered by 12.5 μM E Platinum. Studies of mechanism revealed that E Platinum suppressed activation of mTOR and p70S6K by decreasing phosphorylation of Akt, ERK1/2, JNK and p38 involved in mitogen-activated protein kinase signaling. We supported new evidences for E Platinum as a promising antitumor agent, involving with autophagy induction.
一种被称为自噬的严格调控的分解代谢过程涉及通过溶酶体降解细胞内成分。在这里，我们研究了新合成的奥沙利铂衍生物 E 白金在体内和体外的抗肿瘤作用。E 白金以剂量依赖性方式抑制各种肿瘤细胞的生长，但其机制尚不清楚。基于自噬的理论，我们初步研究了自噬是否有助于 E 白金的抗肿瘤活性。我们的结果表明，E 白金在胃癌 BGC-823 细胞中诱导的自噬，通过 FITC-荧光微管相关蛋白 1 轻链 3（MAP-LC3）、溶酶体丰富/酸性区室用 Lysotracker red（LTR-red）可视化和细胞质内大量大自噬囊泡的积累明显特征化，但在对照细胞中没有。同时，用 12.5 μM E 白金处理细胞会导致水溶性 LC3（LC3-I）转化为脂化和与自噬体相关的形式（LC3-II），以及自噬蛋白 Beclin 1 的表达增加。证明了主要溶酶体天冬氨酸蛋白酶、LAMP-1 和组织蛋白酶 D 的激活。此外，针对 Beclin 1 的 RNA 干扰、自噬的抑制通过 3-甲基腺嘌呤（3-MA）和氯喹显著抑制了上述过程以及由 12.5 μM E 白金触发的 BGC-823 细胞生长抑制。机制研究表明，E 白金通过降低丝氨酸苏氨酸激酶 Akt、细胞外信号调节激酶 1/2（ERK1/2）、c-Jun N-末端激酶（JNK）和 p38 涉及丝裂原激活蛋白激酶信号通路的磷酸化，抑制 mTOR 和 p70S6K 的激活。我们为 E 白金作为一种有前途的抗肿瘤药物提供了新的证据，涉及自噬诱导。
