Rottlerin

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]。