Department of Surgery, Show Chwan Memorial Hospital, Changhua 500, Taiwan.
Department of Biological Science and Technology, China Medical University, Taichung 404, Taiwan.
Int J Mol Sci. 2020 May 16;21(10):3527. doi: 10.3390/ijms21103527.
Magnolol is one of the hydroxylated biphenyl compounds from the root and stem bark of , which shown to possess anti-colorectal cancer (CRC) effects. However, the regulatory mechanism of magnolol on apoptosis and NF-κB signaling in human CRC has not been elucidated. Thus, we investigated the inhibitory mechanism of magnolol on human and mouse CRC (HT-29 and CT-26) in vitro and in vivo. Results from reporter gene assay indicated that both magnolol and rottlerin (PKCδ inhibitor) reduced the endogenous NF-κB activity. In addition, indolactam V (PKCδ activator)-induced NF-κB signaling was significantly suppressed with both magnolol and rottlerin treatment. Results from Western blotting also indicated that phosphorylation of PKCδ and NF-κB -related proteins involved in tumor progression were effectively decreased by magnolol treatment. The invasion capacity of CRC cells was also attenuated by both magnolol and rottlerin. Furthermore, magnolol triggered Fas/Fas-L mediated extrinsic apoptosis and mitochondria mediated intrinsic apoptosis were validated by flow cytometry. Most importantly, tumor growth in both HT-29 and CT-26 bearing mice were suppressed by magnolol, but no pathologic change was detected in mice kidney, spleen, and liver. As confirmed by immunohistochemistry (IHC) staining from tumor tissue, PKCδ/NF-κB signaling and downstream proteins expression were decreased, while apoptotic proteins expression was increased in the magnolol treated group. According to these results, we suggest that the induction of apoptosis through extrinsic/intrinsic pathways and the blockage of PKCδ/NF-κB signaling are associated with the magnolol-inhibited progression of CRC.
厚朴酚是从厚朴的根和茎皮中分离得到的一种羟基化联苯化合物，具有抗结直肠癌（CRC）的作用。然而，厚朴酚对人 CRC 细胞凋亡和 NF-κB 信号通路的调节机制尚未阐明。因此，我们研究了厚朴酚在体外和体内对人源和鼠源 CRC（HT-29 和 CT-26）的抑制机制。报告基因检测结果表明，厚朴酚和罗特林（PKCδ 抑制剂）均可降低内源性 NF-κB 活性。此外，吲哚拉坦 V（PKCδ 激活剂）诱导的 NF-κB 信号通路也被厚朴酚和罗特林的处理显著抑制。Western blot 结果也表明，厚朴酚处理可有效降低 PKCδ 及其相关蛋白的磷酸化，这些蛋白与肿瘤的进展有关。CRC 细胞的侵袭能力也被厚朴酚和罗特林削弱。此外，流式细胞术验证了厚朴酚触发 Fas/Fas-L 介导的细胞外凋亡和线粒体介导的细胞内凋亡。最重要的是，厚朴酚抑制了 HT-29 和 CT-26 荷瘤小鼠的肿瘤生长，但在小鼠的肾脏、脾脏和肝脏中未检测到病理变化。肿瘤组织免疫组化（IHC）染色证实，PKCδ/NF-κB 信号及其下游蛋白的表达减少，而凋亡蛋白的表达增加。根据这些结果，我们认为通过细胞外/细胞内途径诱导凋亡以及阻断 PKCδ/NF-κB 信号通路与厚朴酚抑制 CRC 进展有关。
