Liu Ju-Fang, Chang Chih-Shiang, Fong Yi-Chin, Kuo Sheng-Chu, Tang Chih-Hsin
Department of Pharmacology, School and Medicine, China Medical University and Hospital, Taichung, Taiwan; Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung, Taiwan.
Mol Carcinog. 2012 Apr;51(4):315-26. doi: 10.1002/mc.20787. Epub 2011 May 18.
Chondrosarcoma is the second most common primary bone tumor and it responds poorly to both chemotherapy and radiation treatment. In this study, we investigated the anticancer effects of a new benzimidazole derivative, 2-(furanyl)-5-(piperidinyl)- (3,4,5-trimethoxybenzyl) benzimidazole (FPipTB) in human chondrosarcoma cells. FPipTB-induced apoptosis in human chondrosarcoma cell lines (JJ012 and SW1353) but not in primary chondrocytes. Furthermore, it triggered endoplasmic reticulum (ER) stress, which was characterized by changes in cytosolic calcium levels. Treatment of chondrosarcoma cells with FPipTB was associated with increased intracellular levels of ASK1, p38, p53, and Bax, followed by release of cytochrome c from mitochondria and activation of caspases. It is also known that ER stress activates apoptosis signal-regulating kinase 1 (ASK1), which mediates activation of JNK and p38 pathways. We also found that FPipTB-induced p38 and p53 phosphorylation and upregulated Bax expression. To study the mechanism of Bax upregulation, we determined that Bax promoter activity was increased in FPipTB-treated cells, leading to an increase in intracellular levels of Bax. In addition, cell treated with Ca(2+) chelator or p38 inhibitor showed reduced transcriptional activity. The results further suggest that FPipTB triggered ER stress, as indicated by changes in cytosolic calcium levels and activated the ASK1-MKK3/6-p38-p53-Bax pathway, causing chondrosarcoma cell death. Importantly, animal studies revealed a dramatic 40% reduction in tumor volume after 21 d of treatment. Thus, FPipTB may be a novel anticancer agent for the treatment of chondrosarcoma.
软骨肉瘤是第二常见的原发性骨肿瘤，对化疗和放疗反应均较差。在本研究中，我们调查了一种新型苯并咪唑衍生物2-(呋喃基)-5-(哌啶基)-(3,4,5-三甲氧基苄基)苯并咪唑(FPipTB)对人软骨肉瘤细胞的抗癌作用。FPipTB可诱导人软骨肉瘤细胞系(JJ012和SW1353)凋亡，但对原代软骨细胞无此作用。此外，它引发内质网(ER)应激，其特征为胞质钙水平变化。用FPipTB处理软骨肉瘤细胞与ASK1、p38、p53和Bax细胞内水平升高相关，随后细胞色素c从线粒体释放并激活半胱天冬酶。还已知ER应激激活凋亡信号调节激酶1(ASK1)，后者介导JNK和p38途径的激活。我们还发现FPipTB诱导p38和p53磷酸化并上调Bax表达。为研究Bax上调的机制，我们确定在FPipTB处理的细胞中Bax启动子活性增加，导致细胞内Bax水平升高。此外，用Ca(2+)螯合剂或p38抑制剂处理的细胞显示转录活性降低。结果进一步表明，FPipTB引发了ER应激，表现为胞质钙水平变化，并激活了ASK1-MKK3/6-p38-p53-Bax途径，导致软骨肉瘤细胞死亡。重要的是，动物研究显示治疗21天后肿瘤体积显著减少40%。因此，FPipTB可能是一种治疗软骨肉瘤的新型抗癌药物。
