Department of Medicine Chest, Kaohsiung Armed Forces General Hospital, Kaohsiung 80284, Taiwan ROC.
Department of Biological Sciences, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan ROC.
Phytomedicine. 2021 Apr;84:153502. doi: 10.1016/j.phymed.2021.153502. Epub 2021 Feb 12.
Transforming growth factor‑β (TGF-β) signaling is a crucial inducer of tissue fibrosis and extracellular matrix accumulation and a vital suppressor of epithelial cell proliferation and cancer metastasis. The nature of this multifunctional cytokine has prompted the development of TGF-β signaling inhibitors as therapeutic agents. Our research group has recently isolated the polyprenylated polycyclic acylphloroglucinol garcimultiflorone K (GMK) from the stems of Garcinia multiflora; GMK exhibits antiangiogenic activity in endothelial cells.
In the current study, we aimed to explore the antitumor effect and detailed mechanisms of Garcimultiflorone K in hepatocellular carcinoma cells.
Cell proliferation and viability were evaluated using the MTT assay. The migratory ability of HepG2 cells was measured using wound healing assays. The inhibitory effect of GMK against the nuclear translocation of Smad by TGF-β was assessed through immunofluorescence staining and Western blotting. To investigate TGF-β-dependent gene expression profiles upon GMK stimulation, RNA transcript levels were determined using reverse transcription polymerase chain reaction. The effects of GMK in Smad2-driven transcriptomic activities were studied using a reporter gene assay. Protein levels were detected using Western blotting.
Our data revealed that GMK inhibited TGF-β-induced cellular responses, including Smad protein phosphorylation, cell migration, and extracellular matrix production, during epithelial-mesenchymal transition (EMT). Mechanistic studies further demonstrated that GMK suppressed TGF-β signaling by downregulating TGF-β receptor II (TβRII).
These findings elucidate that TβRII expression in hepatic cells can be specifically suppressed by GMK to attenuate metastasis and the disease-promoting effects of EMT, representing a therapeutic approach.
转化生长因子-β（TGF-β）信号是诱导组织纤维化和细胞外基质积累的关键因子，也是抑制上皮细胞增殖和癌症转移的重要因子。这种多功能细胞因子的特性促使开发 TGF-β 信号抑制剂作为治疗剂。我们的研究小组最近从藤黄属植物的茎中分离出多聚异戊二烯多环酰基间苯三酚 garcimultiflorone K（GMK）；GMK 在血管内皮细胞中表现出抗血管生成活性。
在本研究中，我们旨在探讨 Garcimultiflorone K 对肝癌细胞的抗肿瘤作用及详细机制。
采用 MTT 法评估细胞增殖和活力。通过划痕愈合实验测定 HepG2 细胞的迁移能力。通过免疫荧光染色和 Western blot 评估 GMK 对 TGF-β诱导的 Smad 核转位的抑制作用。为了研究 GMK 刺激后 TGF-β 依赖性基因表达谱，使用逆转录聚合酶链反应测定 RNA 转录水平。通过报告基因实验研究 GMK 在 Smad2 驱动的转录组学活性中的作用。使用 Western blot 检测蛋白水平。
我们的数据表明，GMK 抑制 TGF-β诱导的细胞反应，包括 Smad 蛋白磷酸化、细胞迁移和细胞外基质产生，在上皮-间充质转化（EMT）过程中。机制研究进一步表明，GMK 通过下调 TGF-β 受体 II（TβRII）抑制 TGF-β 信号。
这些发现表明 GMK 可以特异性抑制肝实质细胞中 TβRII 的表达，从而减轻转移和 EMT 的促病作用，代表一种治疗方法。
