Chen Liping, Feng Di, Qian Yafang, Cheng Xiao, Song Huizhu, Qian Yifan, Zhang Xu, Wu Yali, Lv Huawei, Liu Qi, Cheng Gang, Yang Bo, Gu Mancang
College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, China; Academy of Chinese Medical Science, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, China.
College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, China.
Phytomedicine. 2021 May;85:153537. doi: 10.1016/j.phymed.2021.153537. Epub 2021 Mar 3.
Valtrate is a novel epoxy iridoid ester isolated from Chinese herbal medicine Valeriana jatamansi Jones with anti-proliferative activity against various human cancer cell lines. However, its efficacy and molecular mechanisms against pancreatic cancer (PC) cells are largely unclear.
To investigate the anti-cancer effects of valtrate on PC cell lines and its underlying mechanisms.
MTT assay was first performed to detect the effect of valtrate on cell viability in human PC cell lines and normal pancreatic epithelial cells HPDE. Cell apoptosis and cycle phase assay were detected by flow cytometry. The relative mRNA expressions of Bax, Bcl-2, c-Myc, and CyclinB1 were tested by quantitative PCR (qPCR) assay. The expression of relative proteins was detected by Western blotting (WB). A PANC-1 cells xenograft mouse model in nu/nu female mice was used to elucidate the effect of valtrate on tumor growth in vivo.
Valtrate significantly inhibited the growth of PC cells without affecting the growth of normal pancreatic epithelial cells HPDE, induced significant apoptosis and cell cycle arrest in G2/M phase. Moreover, valtrate inhibited the tumor growth of PC cell PANC-1 in xenograft mice by 61%. Further mechanism study demonstrated that valtrate could increase the expression level of Bax, suppress Bcl-2 as well as c-Myc and Cyclin B1, inhibit the transcriptional activity of Stat3, while valtrate decreased the expression level of Stat3 and phosphated-Stat3 (Tyr705) and induced the high molecular aggregation of Stat3. Molecular docking analysis predicted that valtrate might interact with Cys712 of Stat3 protein. Valtrate could also induce a transient depleted intracellular glutathione (GSH) level and increased reactive oxygen species (ROS). NAC (N-acetylcysteine), a reducer reversed valtrate-induced the depletion of Stat3, p-Stat3, c-Myc, and Cyclin B1.
Valtrate exerts anti-cancer activity against PC cells by directly targeting Stat3 through a covalent linkage to inhibit Stat3 activity, which causes apoptosis and cell cycle arrest.
缬草酯是从中药蜘蛛香中分离出的一种新型环氧环烯醚萜酯，对多种人类癌细胞系具有抗增殖活性。然而，其对胰腺癌细胞（PC）的疗效和分子机制尚不清楚。
研究缬草酯对PC细胞系的抗癌作用及其潜在机制。
首先采用MTT法检测缬草酯对人PC细胞系和正常胰腺上皮细胞HPDE细胞活力的影响。通过流式细胞术检测细胞凋亡和细胞周期阶段。采用定量PCR（qPCR）法检测Bax、Bcl-2、c-Myc和CyclinB1的相对mRNA表达。通过蛋白质免疫印迹法（WB）检测相关蛋白的表达。采用nu/nu雌性小鼠的PANC-1细胞异种移植小鼠模型阐明缬草酯对体内肿瘤生长的影响。
缬草酯显著抑制PC细胞生长，而不影响正常胰腺上皮细胞HPDE的生长，诱导显著的细胞凋亡和细胞周期阻滞于G2/M期。此外，缬草酯使异种移植小鼠中PC细胞PANC-1的肿瘤生长抑制了61%。进一步的机制研究表明，缬草酯可增加Bax的表达水平，抑制Bcl-2以及c-Myc和Cyclin B1，抑制Stat3的转录活性，同时缬草酯降低Stat3和磷酸化Stat3（Tyr705）的表达水平，并诱导Stat3的高分子聚集。分子对接分析预测缬草酯可能与Stat3蛋白的Cys712相互作用。缬草酯还可诱导细胞内谷胱甘肽（GSH）水平短暂降低并增加活性氧（ROS）。N-乙酰半胱氨酸（NAC），一种还原剂，可逆转缬草酯诱导的Stat3、p-Stat3、c-Myc和Cyclin B1的消耗。
缬草酯通过与Stat3直接共价连接靶向Stat3以抑制其活性，从而导致细胞凋亡和细胞周期阻滞，发挥对PC细胞的抗癌活性。
