Rottlerin, a natural product purified from Mallotus Philippinensis, is a specific PKC inhibitor, with IC50 values for PKCδ of 3-6μM, PKCα, β, γ of 30-42μM, PKCε, η, ζ of 80-100μM[1]. Rottlerin also acts as a direct mitochondrial uncoupler, and stimulates autophagy by targeting a signaling cascade upstream of mTORC1[2]. Rottlerin is often used in the research of viral infections, neurodegenerative diseases and metabolic disorders[3][4].
In vitro, treatment of human microvascular endothelial cells (HMVECs) with Rottlerin (5 or 20μM; 2, 6, 24h) significantly inhibits the proliferation of cells by reducing thymidine incorporation by 75%–80%, dose-dependently inhibits tube formation on Matrigel with complete inhibition at 20μM after 18h, and reduces cyclin D-1 mRNA to 50%, 40%, and 20% of control levels at 2, 6, and 24h, respectively, with a similar trend observed for protein levels[5]. Additionally, Rottlerin exhibits significant antiproliferative effects on various cell lines, with IC50 values of 12μM for C6 cells (24h), 5μM for C6 cells (48h), 7μM for T98G cells (48h), and 9μM for U138MG cells (48h); reduces the number of S-phase cells in C6, T98G, and U138MG cells at 5μM (24h); and induces DNA laddering in HL-60 cells at 5μM (24h)[6].
In vivo, Rottlerin (20mg/kg/day; p.o.; 6 weeks) significantly inhibited the growth of AsPC-1 pancreatic cancer xenografts in Balb/c nude mice, decreased the expression of cell proliferation markers (Ki67 and PCNA) in tumor tissues, increased the activation of apoptosis markers (caspase-3 and PARP), and suppressed the expression of proteins related to angiogenesis (VEGF, VEGFR, Cox-2, IL-8) and epithelial–mesenchymal transition (Slug, Snail, MMP-2, MMP-9), while upregulating the expression of E-cadherin[7].
References:
[1] Gschwendt M, Müller HJ, Kielbassa K, et al. Rottlerin, a novel protein kinase inhibitor. Biochem Biophys Res Commun. 1994;199(1):93-98.
[2] Balgi AD, Fonseca BD, Donohue E, et al. Screen for chemical modulators of autophagy reveals novel therapeutic inhibitors of mTORC1 signaling. PLoS One. 2009;4(9):e7124.
[3] Lama Z, Gaudin Y, Blondel D, Lagaudrière-Gesbert C. Kinase inhibitors tyrphostin 9 and rottlerin block early steps of rabies virus cycle. Antiviral Res. 2019;168:51-60.
[4] Zhang D, Anantharam V, Kanthasamy A, Kanthasamy AG. Neuroprotective effect of protein kinase C delta inhibitor rottlerin in cell culture and animal models of Parkinson's disease. J Pharmacol Exp Ther. 2007;322(3):913-922.
[5] Valacchi G, Pecorelli A, Sticozzi C, et al. Rottlerin exhibits antiangiogenic effects in vitro. Chem Biol Drug Des. 2011;77(6):460-470.
[6] Parmer TG, Ward MD, Hait WN. Effects of rottlerin, an inhibitor of calmodulin-dependent protein kinase III, on cellular proliferation, viability, and cell cycle distribution in malignant glioma cells. Cell Growth Differ. 1997;8(3):327-334.
[7] Huang M, Tang SN, Upadhyay G, et al. Rottlerin suppresses growth of human pancreatic tumors in nude mice, and pancreatic cancer cells isolated from Kras(G12D) mice. Cancer Lett. 2014;353(1):32-40.
Rottlerin 是从Mallotus Philippinensis中纯化得到的天然产物，是一种特异性蛋白激酶C（PKC）抑制剂，对PKCδ的 IC50 值为3-6μM，对PKCα、β、γ 的IC50值为30-42μM，对PKCε、η、ζ 的IC50值为 80-100μM[1]。Rottlerin还作为一种直接的线粒体解偶联剂，通过靶向mTORC1上游的信号级联来刺激自噬[2]。Rottlerin常用于病毒感染、神经退行性疾病和代谢紊乱的研究[3][4]。
在体外，用Rottlerin（5或20μM；2、6、24小时）处理人微血管内皮细胞（HMVEC）显著抑制细胞增殖，使胸腺嘧啶掺入减少75%–80%，呈剂量依赖性地抑制Matrigel上的管状结构形成，20μM时在18小时后完全抑制，并在2、6和24小时时分别使cyclin D-1 mRNA 降低至对照组的 50%、40%和20%，蛋白水平也呈现类似趋势[5]。此外，Rottlerin对多种细胞系表现出显著的抗增殖效果，C6细胞（24小时）的 IC50 值为 12μM，C6细胞（48 小时）的IC50值为5μM，T98G细胞（48 小时）的IC50值为7μM，U138MG细胞（48小时）的IC50值为9μM；在5μM（24小时）时减少C6、T98G和U138MG细胞中S期细胞的数量并诱导HL-60细胞中DNA梯状条带的形成[6]。
在体内，Rottlerin（20mg/kg/天；口服；6周）显著抑制了Balb/c裸鼠中AsPC-1胰腺癌异种移植瘤的生长，降低了肿瘤组织中细胞增殖标志物（Ki67和PCNA）的表达，增加了凋亡标志物（caspase-3 和 PARP）的激活，并抑制了与血管生成（VEGF、VEGFR、Cox-2、IL-8）和上皮 - 间充质转化（Slug、Snail、MMP-2、MMP-9）相关的蛋白表达，同时上调了E-cadherin的表达[7]。