Rottlerin

Chem Biol Drug Des . 2011 Jun;77(6):460-70.

Rottlerin exhibits antiangiogenic effects in vitro[Pubmed: 21435184]

Rottlerin, a natural product purified from Mallotus philippinensis, has a number of target molecules and biological effects. We recently found that Rottlerin caused growth arrest in MCF-7 breast cancer cells and human immortalized keratinocytes, through inhibition of NFκB and downregulation of cyclin D-1. To evaluate whether this effect could be generalized to primary cells, human microvascular endothelial cells were treated with Rottlerin. In this study, we demonstrated that Rottlerin prevents basal and TNFα-stimulated NFκB nuclear migration and DNA binding also in human microvascular endothelial cell, where NFκB inhibition was accompanied by the downregulation of NFκB target gene products, such as cyclin D-1 and endothelin-1, which are essential molecules for endothelial cell proliferation and survival. Rottlerin, indeed, inhibited human microvascular endothelial cells proliferation and tube formation on Matrigel. Rottlerin also increases cytoplasmic free calcium and nitric oxide levels and downregulates endothelin converting enzyme-1 expression, thus contributing to the drop in endothelin-1 and growth arrest. These results suggest that Rottlerin may prove useful in the development of therapeutic agents against angiogenesis.

Cancer Lett . 2014 Oct 10;353(1):32-40.

Rottlerin suppresses growth of human pancreatic tumors in nude mice, and pancreatic cancer cells isolated from Kras(G12D) mice[Pubmed: 25050737]

The purpose of the study was to examine the molecular mechanisms by which Rottlerin inhibited growth of human pancreatic tumors in Balb C nude mice, and pancreatic cancer cells isolated from Kras(G12D) mice. AsPC-1 cells were injected subcutaneously into Balb c nude mice, and tumor-bearing mice were treated with Rottlerin. Cell proliferation and apoptosis were measured by Ki67 and TUNEL staining, respectively. The expression of components of Akt, Notch, and Sonic Hedgehog (Shh) pathways were measured by the immunohistochemistry, Western blot analysis, and/or q-RT-PCR. The effects of Rottlerin on pancreatic cancer cells isolated from Kras(G12D) mice were also examined. Rottlerin-treated mice showed a significant inhibition in tumor growth which was associated with suppression of cell proliferation, activation of capase-3 and cleavage of PARP. Rottlerin inhibited the expression of Bcl-2, cyclin D1, CDK2 and CDK6, and induced the expression of Bax in tumor tissues compared to untreated control. Rottlerin inhibited the markers of angiogenesis (Cox-2, VEGF, VEGFR, and IL-8), and metastasis (MMP-2 and MMP-9), thus blocking production of tumorigenic mediators in tumor microenvironment. Rottlerin also inhibited epithelial-mesenchymal transition by up-regulating E-cadherin and inhibiting the expression of Slug and Snail. Furthermore, Rottlerin treatment of xenografted tumors or pancreatic cancer cells isolated from Kras(G12D) mice showed a significant inhibition in Akt, Shh and Notch pathways compared to control groups. These data suggest that Rottlerin can inhibit pancreatic cancer growth by suppressing multiple signaling pathways which are constitutively active in pancreatic cancer. Taken together, our data show that the Rottlerin induces apoptosis and inhibits pancreatic cancer growth by targeting Akt, Notch and Shh signaling pathways, and provide a new therapeutic approach with translational potential for humans.

Biochem Biophys Res Commun . 1994 Feb 28;199(1):93-98.

Rottlerin, a novel protein kinase inhibitor[Pubmed: 8123051]

Rottlerin, a compound from Mallotus philippinensis, is shown to inhibit protein kinases with some specificity for PKC. To some extent, the novel inhibitor is able to differentiate between PKC isoenzymes, with IC50 values for PKC delta of 3-6 microM, PKC alpha,beta,gamma of 30-42 microM and PKC epsilon,eta,zeta of 80-100 microM. Inhibition of PKC appears, at least in part, to be due to a competition between Rottlerin and ATP. Among the protein kinases tested, only CaM-kinase III is suppressed by Rottlerin as effectively as PKC delta. The chemical structure of Rottlerin might serve as a basis for the development of novel inhibitors with improved selectivity for a distinct PKC isoenzyme, such as PKC delta, or for CaM-kinase III.

Antiviral Res . 2019 Aug;168:51-60.

Kinase inhibitors tyrphostin 9 and rottlerin block early steps of rabies virus cycle[Pubmed: 31071352]

Rabies virus (RABV) is a neurotropic virus that causes fatal encephalitis in humans and animals and still kills up to 59,000 people worldwide every year. To date, only preventive or post-exposure vaccination protects against the disease but therapeutics are missing. After screening a library of 80 kinases inhibitors, we identified two compounds as potent inhibitors of RABV infection: tyrphostin 9 and Rottlerin. Mechanism of action studies show that both inhibitors interfere with an early step of viral cycle and can prevent viral replication. In presence of tyrphostin 9, the viral entry through endocytosis is disturbed leading to improper delivery of viral particles in cytoplasm, whereas Rottlerin is inhibiting the transcription, most likely by decreasing intracellular ATP concentration, and therefore the replication of the viral genome.

J Biol Chem . 2011 Aug 5;286(31):27363-27377.

Protein kinase Ctheta is a specific target for inhibition of the HIV type 1 replication in CD4+ T lymphocytes[Pubmed: 21669868]

Integration of HIV-1 genome in CD4(+) T cells produces latent reservoirs with long half-life that impedes the eradication of the infection. Control of viral replication is essential to reduce the size of latent reservoirs, mainly during primary infection when HIV-1 infects CD4(+) T cells massively. The addition of immunosuppressive agents to highly active antiretroviral therapy during primary infection would suppress HIV-1 replication by limiting T cell activation, but these agents show potential risk for causing lymphoproliferative disorders. Selective inhibition of PKC, crucial for T cell function, would limit T cell activation and HIV-1 replication without causing general immunosuppression due to PKC being mostly expressed in T cells. Accordingly, the effect of Rottlerin, a dose-dependent PKC inhibitor, on HIV-1 replication was analyzed in T cells. Rottlerin was able to reduce HIV-1 replication more than 20-fold in MT-2 (IC(50) = 5.2 μM) and Jurkat (IC(50) = 2.2 μM) cells and more than 4-fold in peripheral blood lymphocytes (IC(50) = 4.4 μM). Selective inhibition of PKC, but not PKCδ or -ζ, was observed at <6.0 μM, decreasing the phosphorylation at residue Thr(538) on the kinase catalytic domain activation loop and avoiding PKC translocation to the lipid rafts. Consequently, the main effector at the end of PKC pathway, NF-κB, was repressed. Rottlerin also caused a significant inhibition of HIV-1 integration. Recently, several specific PKC inhibitors have been designed for the treatment of autoimmune diseases. Using these inhibitors in combination with highly active antiretroviral therapy during primary infection could be helpful to avoid massive viral infection and replication from infected CD4(+) T cells, reducing the reservoir size at early stages of the infection.

J Chromatogr Sep Tech . 2013 Jan 1;4(1):100062.

Determination of Rottlerin, a Natural Protein Kinases C Inhibitor, in Pancreatic Cancer Cells and Mouse Xenografts by RP-HPLC Method[Pubmed: 24482742]

Rottlerin is a natural polyphenolic ketone isolated from the pericarps of Mallotus phillippinensis. In previous studies we showed that parenteral administration of Rottlerin reduced tumor growth in murine xenograft models of pancreatic cancer. The aim of this study was to develop a simple and validated method for the quantitative determination of Rottlerin in plasma and tumor tissues of mice fed a Rottlerin diet. A xenograft model of pancreatic cancer was prepared by injection of 2×106 HPAF-II cells subcutaneously into nude mice. One week before tumor implantation, mice were randomly allocated to standard diet (AIN76A) and standard diet supplement with 0.012% Rottlerin (n=6 per group). Mice were sacrificed after 6 weeks on diets. Rottlerin was extracted from the plasma and tissues using protein precipitation-extraction and analyzed by reverse-phase HPLC-DAD method. The same HPLC method was also applied to determine Rottlerin levels in conditioned culture media and in cell lysates from HPAF-II cells exposed to 25 μM concentration of Rottlerin. A substantial amount of Rottlerin was detected in tumor (2.11 ± 0.25 nmol/g tissue) and plasma (2.88 ± 0.41 μM) in mice fed Rottlerin diet. In addition, significant levels of Rottlerin (57.4 ± 5.4 nmol/mg protein) were detected in cell lysates from Rottlerin-treated HPAF-II cells. These data indicate that Rottlerin is efficiently absorbed in cells and tissues both in vivo and in vitro and suggest a strong potential for Rottlerin as a preventive or adjuvant supplement for pancreatic cancer.