Rottlerin, a Novel Protein Kinase Inhibitor

Gschwendt, Michael; Müller, Hans‐Joachim; Kielbassa, Kirsten; Zang, Rukun; Kittstein, Walter; Rincke, Gabriele; Marks, Friedrich

doi:10.1006/bbrc.1994.1199

Cited by 789 publications

(678 citation statements)

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“…We found that PKCδ plays a critical role in STAT-3 signalling in these cells, since the addition of rottlerin inhibited: (1) IL-6-induced Tyr-705 and Ser-727 phosphorylation of STAT3; (2) nuclear translocation and transcriptional binding of STAT3; (3) IL-6-induced activation of inflammatory genes like Il-6, Saa3 and Hp, as well as the feed-back inhibitor Socs3; and (4) SAA3 secretion to the culture medium. Although rottlerin has been claimed to be a specific inhibitor of PKCδ [30], recent studies have shown that it may have additional effects in the mitochondria and on 5′-AMP-activated protein kinase [31,32]. Therefore, we further corroborated our findings in 3T3-L1 cells with rottlerin by using Pkcδ −/− MEFs.…”

Section: Discussionsupporting

confidence: 84%

Protein kinase C-δ is involved in the inflammatory effect of IL-6 in mouse adipose cells

2010

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Aims/hypothesis The aim of the study was to address the role of protein kinase C-δ (PKCδ) on phosphorylation of signal transducer and activator of transcription 3 (STAT3) and activation of inflammatory genes in response to IL-6 in adipose cells. Methods Differentiated mouse 3T3-L1 adipocytes preincubated with the PKCδ inhibitor rottlerin and mouse embryonic fibroblasts (MEFs) lacking PKCδ were incubated with IL-6 and/or insulin. RNA was extracted and the gene expression was analysed by real-time PCR, while the proteins from total, nuclear and cytoplasmic lysates were analysed by immunoblotting. Results Inhibition of PKCδ by rottlerin significantly reduced both Ser-727 and Tyr-705 phosphorylation of STAT3. Consequently, nuclear translocation of STAT3 and the IL-6-induced gene transcription and protein release of the inflammatory molecule serum amyloid A 3 (SAA3) were reduced. Similarly, the IL-6-regulated gene transcription of Il-6 (also known as Il6) to Hp and the feedback inhibitor of IL-6, Socs3, were also attenuated by rottlerin. Furthermore, PKCδ was found to translocate to the nucleus following IL-6 treatment and this was also reduced by rottlerin. In agreement with the effect of rottlerin, Pkcδ (also known as Prkcd) −/− MEFs also displayed a markedly reduced ability of IL-6 to activate the transcription of Saa3, Hp, Socs3 and Il6 genes compared with wild-type MEFs. These results correlated with a reduced nuclear translocation and phosphorylation of STAT3. Conclusions/interpretation These results show that PKCδ plays a key role in the inflammatory effect of IL-6 in adipose cells and may be a suitable target for novel antiinflammatory agents.

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Section: Discussionsupporting

confidence: 84%

Protein kinase C-δ is involved in the inflammatory effect of IL-6 in mouse adipose cells

2010

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“…1C), confirming that PKCy regulates TG2 mRNA expression. Rottlerin has been shown to block PKCy specifically at concentrations between 3 and 6 Amol/L (20). However, at higher concentrations, it can also inhibit other isoforms of PKC.…”

Section: Inhibition Of Pkcd Results In Down-regulation Of Tg2mentioning

confidence: 99%

Tissue Transglutaminase Inhibits Autophagy in Pancreatic Cancer Cells

Akar

Özpolat

Mehta

et al. 2007

Molecular Cancer Research

119

107

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Elevated expression of tissue transglutaminase (TG2) in cancer cells has been implicated in the development of drug resistance and metastatic phenotypes. However, the role and the mechanisms that regulate TG2 expression remain elusive. Here, we provide evidence that protein kinase CD (PKCD) regulates TG2 expression, which in turn inhibits autophagy, a type II programmed cell death, in pancreatic cancer cells that are frequently insensitive to standard chemotherapeutic agents. Rottlerin, a PKCD-specific inhibitor, and PKCD small interfering RNA (siRNA) down-regulated the expression of TG2 mRNA and protein and induced growth inhibition without inducing apoptosis in pancreatic cancer cells. Inhibition of PKCD by rottlerin or knockdown of TG2 protein by a TG2-specific siRNA resulted in a marked increase in autophagy shown by presence of autophagic vacuoles in the cytoplasm, formation of the acidic vesicular organelles, membrane association of microtubule-associated protein 1 light chain 3 (LC3) with autophagosomes, and a marked induction of LC3-II protein, important hallmarks of autophagy, and by electron microscopy. Furthermore, inhibition of TG2 by rottlerin or by the siRNA led to accumulation of green fluorescent protein (GFP)-LC3-II in autophagosomes in pancreatic cancer cells transfected with GFP-LC3 (GFP-ATG8) expression vector. Knockdown of Beclin-1, a specific autophagy-promoting protein and the product of Becn1 (ATG6), inhibited rottlerin-induced and TG2 siRNA -induced autophagy, indicating that Beclin-1 is required for this process. These results revealed that PKCD plays a critical role in the expression of TG2, which in turn regulates autophagy. In conclusion, these results suggest a novel mechanism of regulation of TG2 and TG2-mediated autophagy in pancreatic cancer cells.

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“…These 15 compounds inhibit various kinases with nanomolar to micromolar IC 50 values. For instance, rottlerin is marketed as a PKCδ inhibitor with an IC 50 of 3 µM, 16 and quercetin is advertised as a PI3-K inhibitor with an IC 50 of 3.8 µM. 17 Eight of the 15 compounds inhibited the model non-kinase enzymes with micromolar IC 50 values.…”

Section: Resultsmentioning

confidence: 99%

Kinase Inhibitors: Not Just for Kinases Anymore

2003

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Kinase inhibitors are widely employed as biological reagents and as leads for drug design. Their use is often complicated by their lack of specificity. Although binding conserved ATP sites accounts for some of their nonspecificity, some compounds inhibit proteins not known to bind ATP. It has been found that promiscuous hits from high-throughput screening may act as aggregates. To explore whether this mechanism might explain the action of widely used nonspecific kinase inhibitors, 15 such compounds were studied. Eight of these, rottlerin, quercetin, K-252c, bisindolylmaleimide I, bisindolylmaleimide IX, U0126, indirubin, and indigo, inhibited three diverse non-kinase enzymes. Inhibition was time-dependent and sensitive to enzyme concentration; by light scattering, the compounds formed particles of 100-1000 nm diameter. These observations suggest that these eight kinase inhibitors, at least at micromolar concentrations, are promiscuous and act as aggregates. Results obtained from the use of these compounds at micromolar or higher concentrations against individual enzymes should be interpreted cautiously.

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Rottlerin, a Novel Protein Kinase Inhibitor

Cited by 789 publications

References 0 publications

Protein kinase C-δ is involved in the inflammatory effect of IL-6 in mouse adipose cells

Protein kinase C-δ is involved in the inflammatory effect of IL-6 in mouse adipose cells

Tissue Transglutaminase Inhibits Autophagy in Pancreatic Cancer Cells

Kinase Inhibitors: Not Just for Kinases Anymore

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