Bisindolylmaleimide Derivatives Research Articles

PKC signal amplification suppresses non-small cell lung cancer growth by promoting p21 expression and phosphorylation

Protein kinase C (PKC) activation was previously associated with oncogenic features. However, small molecule inhibitors targeting PKC have so far proved ineffective in a number of clinical trials for cancer treatment. Recent progresses have revealed that most PKC mutations detected in diverse cancers actually lead to loss-of-function, thus suggesting the tumor-suppressive roles of PKC proteins. Unfortunately, the development of chemicals to enhance PKC activity is lagging behind relative to its small molecular inhibitors. Here, we report that a bisindolylmaleimide derivative (3,4-bis(1-(prop-2-ynyl)-1H-indol-3-yl)-1 H-pyrrole-2,5-dione, BD-15) significantly inhibited cell growth in non-small cell lung cancer (NSCLC). Mechanistically, BD-15 treatment resulted in markedly enhanced phosphorylation of PKC substrates and led to cell cycle arrest in G2/M. Further, BD-15 treatment upregulated p21 protein levels and enhanced p21 phosphorylation. BD-15 also promoted caspase3 cleavage and triggered cellular apoptosis. In xenograft mouse models, BD-15 exerted anti-tumor effects to suppress in vivo tumor formation. Collectively, our findings revealed the tumor-suppressive roles of BD-15 through enhancing PKC signaling and thus leading to upregulation of p21 expression and phosphorylation.

Hypomorph mutation-directed small-molecule protein-protein interaction inducers to restore mutant SMAD4-suppressed TGF-β signaling

Tumor suppressor genes represent a major class of oncogenic drivers. However, direct targeting of loss-of-function tumor suppressors remains challenging. To address this gap, we explored a variant-directed chemical biology approach to reverse the lost function of tumor suppressors using SMAD4 as an example. SMAD4, a central mediator of the TGF-β pathway, is recurrently mutated in many tumors. Here, we report the development of a TR-FRET technology that recapitulated the dynamic differential interaction of SMAD4 and SMAD4R361H with SMAD3 and identified Ro-31-8220, a bisindolylmaleimide derivative, as a SMAD4R361H/SMAD3 interaction inducer. Ro-31-8220 reactivated the dormant SMAD4R361H-mediated transcriptional activity and restored TGF-β-induced tumor suppression activity in SMAD4 mutant cancer cells. Thus, demonstration of Ro-31-8220 as a SMAD4R361H/SMAD3 interaction inducer illustrates a general strategy to reverse the lost function of tumor suppressors with hypomorph mutations and supports a systematic approach to develop small-molecule protein-protein interaction (PPI) molecular glues for biological insights and therapeutic discovery.

Metal ion-induced coordination and cyclization of crown ether-based bisindolylmaleimides: different fluorescence responses and applications in complex logical operations

Bisindolylmaleimide derivatives with crown ether display different interaction mechanisms with metal ions: coordination and oxidative cyclization, causing red and green emission, respectively, which can be used to construct advanced logic systems.

Small-molecule inhibition of pyruvate phosphate dikinase targeting the nucleotide binding site.

Pyruvate phosphate dikinase (PPDK) is an essential enzyme of C4 photosynthesis in plants, catalyzing the ATP-driven conversion of pyruvate to phosphoenolpyruvate (PEP). It is further used by some bacteria and unicellular protists in the reverse, ATP-forming direction. Many weed species use C4 photosynthesis in contrast to world’s major crops, which are C3 plants. Hence inhibitors of PPDK may be used as C4-specific herbicides. By screening a library of 80 commercially available kinase inhibitors, we identified compounds derived from bisindolylmaleimide (bisindolylmaleimide IV, IC50 = 0.76 ± 0.13 μM) and indirubin (indirubin-3’-monoxime, IC50 = 4.2 ± 0.9 μM) that showed high inhibitory potency towards PPDK and are among the most effective PPDK inhibitors described today. Physiological studies on leaf tissues of a C4 model plant confirmed in vivo inhibition of C4-driven photosynthesis by these substances. Moreover, comparative docking studies of non-inhibitory bisindolylmaleimide derivatives suggest that the selectivity towards PPDK may be increased by addition of functional groups to the core structure.

Solvent-dependent and highly selective anion sensing and molecular logic application of bisindolylmaleimide derivatives

Bisindolylmaleimide derivatives (IMs) were found to be sensitive to different anions in various solvents, and utilized to construct five logic devices.

Identification of Bisindolylmaleimide IX as a potential agent to treat drug-resistant BCR-ABL positive leukemia.

Chronic myeloid leukemia (CML) treatment with BCR-ABL inhibitors is often hampered by development of drug resistance. In a screen for novel chemotherapeutic drug candidates with genotoxic activity, we identified a bisindolylmaleimide derivative, IX, as a small molecule compound with therapeutic potential against CML including drug-resistant CML. We show that Bisindolylmaleimide IX inhibits DNA topoisomerase, generates DNA breaks, activates the Atm-p53 and Atm-Chk2 pathways, and induces cell cycle arrest and cell death. Interestingly, Bisindolylmaleimide IX is highly effective in targeting cells positive for BCR-ABL. BCR-ABL positive cells display enhanced DNA damage and increased cell cycle arrest in response to Bisindolylmaleimide IX due to decreased expression of topoisomerases. Cells positive for BCR-ABL or drug-resistant T315I BCR-ABL also display increased cytotoxicity since Bisindolylmaleimide IX inhibits B-Raf and the downstream oncogene addiction pathway. Mouse cancer model experiments showed that Bisindolylmaleimide IX, at doses that show little side effect, was effective in treating leukemia-like disorders induced by BCR-ABL or T315I BCR-ABL, and prolonged the lifespan of these model mice. Thus, Bisindolylmaleimide IX presents a novel drug candidate to treat drug-resistant CML via activating BCR-ABL-dependent genotoxic stress response and inhibiting the oncogene addiction pathway activated by BCR-ABL.

Amide-based diarylmaleimide derivatives and polymers: Highly selective and ratiometric fluorescence sensing for anions

A series of diarylmaleimide derivatives and polymers based on amide group were designed and synthesized to detect anions selectively and sensitively. Three bisindolylmaleimide derivatives (FAM-p, FAM-m and FAM-o) employing trifluoroacetamide as receptor exhibited strong fluorescent quenching upon fluoride and cyanide. Trifluoroacetamide receptor was replaced by acetamide to obtain other two derivatives (AM-p and AM-o) which showed higher selectivity than FAMs with sensing for only fluoride. The diarylmaleimide derivatives were introduced into the backbone of polyfluorene by Suzuki reaction to prepare polymer PFAM and PAM with same sensing selectivity for anions as FAM and AM, respectively. PFAM and PAM were found to be ratiometric fluorescence sensors for a fluorescence resonance energy transfer (FRET) from fluorene segments to diphenylmaleimide units. The experimental and DFT/TDDFT calculation results demonstrated that the interaction mechanism of FAMs with F− and CN− was hydrogen bond interaction and nucleophilic addition reaction, respectively.

Synthesis of Novel Bisindolylmaleimide Derivatives

Four novel bisindolylmaleimides 9a, 9b, 9d, 9e containing different aminoalkyl side chains were derived from methylsulfonylation, ammonolysis of the intermediate 7, which was prepared by reaction of methyl(1-(3-O'-tetrahydro- pyranepropyl)indolyl-3)-glyoxylate (5) with indole-3-acetamides (6) using t-BuOK in THF as catalyst and treatment using concentrated hydrochloric acid subsequently. The structures of target products were also confirmed by 1 H NMR, 13 C NMR,

Toggle-switchable fluorescence of bisindolylmaleimide derivatives by reversible esterification/hydrolysis

Isomers based on the bisindolylmaleimide architecture were reported in this Letter. Introducing hydroxyl to this architecture lead to quenching the fluorescence of bisindolylmaleimide. The fluorescence was recovered with its hydroxyl group esterified. Ester group can be easily transformed to hydroxyl group by hydrolysis reaction. Thus, a toggle-switchable fluorescence, ‘off–on’ cycle can be established on the basis of reversible esterification/hydrolysis reaction.

Synthesis of novel 3,4-diaryl-5-aminopyrazoles as potential kinase inhibitors

Synthesis of a diverse series of novel 3,4-diaryl-5-aminopyrazoles as candidates in the development of new protein kinase inhibitors is reported for the first time. In the course of a wider study into bisindolylmaleimide (BIM) derivatives, we examined a novel 5-aminopyrazole heterocyclic moiety as a structural analogue of the highly potent VEGF-R2/3 inhibitor pyrrole-2-one ( 8). The versatile nature of this pharmacophore allows considerable scope for derivatisation and hence exploration of structure activity relationships. Consequently, a variety of structural modifications were used in order to diversify the aminopyrazole ring substituents. Bicyclic derivatives of the parent aminopyrazoles ( 11, 12) were also synthesised as a means of probing the kinase active site, leading to formation of complex planar pyrimidine moieties. This work provides the framework for new explorations into kinase inhibition and critical investigations into selectivity of inhibitory activity.

Theoretical Study of Photophysical Properties of Bisindolylmaleimide Derivatives

The photophysical properties of two bisindolylmaleimide derivatives, 3,4-bis(3-indolyl)-1-H-pyrrole-2,5-dione (arcyriarubin A) and indolo[2,3-a]pyrrolo[3,4-c] carbazole-5,7-(6 H)-dione (arcyriaflavin A), are investigated by using ab initio molecular orbital (MO) and multireference perturbation theory. These compounds are suggested to exist as monovalent anions deprotonated from an indole NH group in aprotic polar solvents. The analysis of MOs shows that the electronic structures of the S(1) and S(2) states are described by the single- or double-electron excitation between the naturally localized MOs on an indole moiety and on the maleimide part. This indicates that the intramolecular charge transfer (ICT) transfer may occur by photoexcitation. The minimum-energy structure of the arcyriarubin A anion is twisted; the dihedral angles between the indole and maleimide rings are 83.4 degrees and 20.2 degrees for the S(1) and S(0) states, respectively. The analysis of the minimum energy path along the coordinate of the twist angle is performed to explore the emission process from the S(1) state. It has been shown that the magnitude of the Stokes shift increases with increasing the twist angle, but the oscillator strength decreases. It has been suggested that the experimentally observed fluorescence arises on the way toward the energy minimum of the S(1) state. The Stokes-shifted emission of arcyriaflavin A is contributed by the S(1)-S(0) electronic relaxation after the excitation in the S(2) state.

Dye-sensitized solar cells based on bisindolylmaleimide derivatives

Three organic dyes based on bisindolylmaleimide derivatives (I1, I2 and I3) were synthesized and investigated as sensitizers for the application in nanocrystalline TiO2 solar cells. The indole group, maleimide group and carboxylic group functioned as electron donor, acceptor and anchoring group, respectively. Solar-to-electrical energy conversion efficiencies under simulated amplitude-modulated 1.5 irradiation (100 mW·cm−2) of 2.07% were obtained for solar cells based on I2 and of 1.87% and 1.50% for I3 and I1, respectively. The open circuit voltage Voc was demonstrated to be enhanced by the introduction of dodecyl or benzyl moieties on the indole groups. The nonplanar structure of bisindolylmaleimide was proven to be effective in aggregation resistance. This work suggests that organic sensitizers with maleimide as electron acceptor are promising candidates as organic sensitizers in dye-sensitized solar cells.

Bisindolylmaleimides in anti-cancer therapy - more than PKC inhibitors

Bisindolylmaleimide derivatives were originally described as protein kinase C inhibitors. However, several studies have shown that bisindolylmaleimides target several other signaling molecules. The review presents bisindolylmaleimide-mediated PKC-dependent and PKC-independent biological effects, such as reversal of MDR and modulation of Wnt signaling through GSK-3b and b-catenin. Importantly, the potent proapoptotic properties of bisindolylmaleimides are also described. Bis-IX appears as the most efficient activator of intrinsic apoptotic pathway and additionally, facilitates extrinsic apoptosis. Presented molecular mechanisms indicate that bisindolylmaleimides could be useful agents in anticancer therapy. They repress uncontrolled proliferation and restore the sensitivity to chemotherapy which allows eradication of cancer cells.

Novel bisindolylmaleimide derivative inhibits mitochondrial permeability transition pore and protects the heart from reperfusion injury

Despite major advances in treating patients with coronary heart disease, reperfusion injury is still considered to be a major problem, especially in surgical settings. Here, we demonstrate the protective effects of a novel bisindolylmaleimide derivative, MS1 (2-[1-(3-aminopropyl)indol-3-yl]-3-(indol-3-yl)-N-methylmaleimide), against reperfusion injury of the heart. After anesthesia and artificial ventilation, Wistar rats were subjected to 30 min of left coronary artery occlusion followed by 120 min of reperfusion with or without treating the rats with MS1 (2.25 mumol.L-1.kg-1) before left coronary artery occlusion. Compared with the untreated hearts, MS1 treatment significantly reduced myocardial infarct size (35.1% +/- 3% vs. 75.5% +/- 5%, p < 0.001), reduced prevalence of apoptotic cells (2.6% +/- 0.5% vs. 12.2% +/- 2.1%, p < 0.001), prevented mitochondrial swelling and cytochrome c release, inhibited downregulation of antiapoptotic protein Bcl-2 expression, and suppressed caspase-3 activation. In contrast, pretreatment with atractyloside, a mitochondrial permeability transition pore opener, abolished the protective effects of MS1. In conclusion, MS1 inhibits pathologic opening of permeability transition pores and protects the heart against reperfusion injury and pathologic apoptosis.

A Novel Bisindolylmaleimide Derivative Enhances Functional Recovery of Heart After Long-Term Hypothermic Heart Preservation

Functional recovery following heart transplantation mainly depends on the ability of preservative solution in providing the physical and biochemical environment so as to maintain the viability of the tissue during preservation and in reperfusion. Here we demonstrate the protective effects of a novel bisindolylmaleimide derivative, MS1, on enhancing the functional recovery of the heart following long-term hypothermic preservation when added to the preservative solution. After anesthesia and artificial ventilation, the hearts were rapidly isolated and perfused with Kreb's Henseleit buffer at 37 degrees C in working mode. After 30 minutes of perfusion, the hearts were arrested with cardioplegic solution and preserved in University of Wisconsin solution with (UW-MS1 group) or without MS1 (UW-Vehicle group) for 12 h at 4 degrees C. After 12 hours, the hearts were reperfused for 60 minutes. MS1 treated hearts showed: a) significant recovery of cardiac functions (P<0.001), b) well-preserved myocardial ATP levels (P<0.001), c) less myocardial water content (P<0.01), d) reduced oxidative stress (P<0.001), e) less intracellular swelling and well-preserved mitochondria, and g) activation of cell survival cascades compared to the control hearts preserved in UW solution without MS1. In contrast, these protective effects of MS1 were abolished on opening the permeability transition pore before MS1 treatment. These results altogether indicate the efficacy of this compound in protecting the myocardium against reperfusion injury and thus making this drug a clinically useful tool in patients undergoing reperfusion after cardiac surgeries.

Bisindolylmaleimide derivatives as non-doped red organic light-emitting materials

A new series of bisindolylmaleimide (BIM) derivatives were synthesized. The absorption and fluorescence properties of these compounds were investigated in solution and solid state. Dramatic difference in solid-state fluorescence emission spectra was observed by changing the substituents on the fluorophores skeleton from methyl to benzyl. We performed X-ray crystallographic analyses to elucidate the effect of the substituents of the non-conjugated linkage on the solid-state fluorescence emission spectra. The relationships between the solid-state photophysical properties and the chemical and crystal structures of 2,3-bis( N-benzyl-2′methyl-3′-indolyl)- N-methylmaleimide ( 1S) and 2,3-bis( N-benzyl-2′methyl-3′-indolyl)- N-benzylmaleimide ( 5S) are discussed on the basis of the X-ray crystal data. Bis[2,3-bis( N-ethyl-2′methyl-3′-indolyl)- N-(prop-2-ynyl)maleimide] ( 1B) and 1S were utilized in non-doping host red EL device. The brightness reaches 393 cd m −2 at 100 mA cm −2 for 1S.

Electroluminescence of Bisindolylmaleimide Derivatives Containing Pentafluorophenyl Substituents

Bisindolylmaleimide derivatives containing nonfluorinated (1−3) and fluorinated (1F−4F) substituents were synthesized, and their performances on electroluminescence devices were compared. Two kinds of devices were fabricated, in which either AlQ3 (tris(8-hydroxyquinolinato)aluminum) or TPBI (2,2‘,2‘ ‘-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)) was used as an electron-transporting (ET) medium. For nonfluorinated materials 1−3, a red emission was obtained in devices with an ITO/NPB/1−3/TPBI/Mg:Ag configuration (ITO and NPB denote indium−tin oxide and 4,4‘-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, respectively), whereas dual emissions were observed in others using AlQ3 as the ET material. For fluorinated materials 1F−4F, dual emissions were observed in both kinds of devices. The second emission came from the ET layer, although a certain number of holes were annihilated with the electrons there. Compounds bearing pentafluorophenyl moieties exhibited a reduced potential energy for both the HOMO and ...

Protein Kinase C Pathway Is Involved in Transcriptional Regulation of C-Reactive Protein Synthesis in Human Hepatocytes

C-reactive protein (CRP) is the prototype acute phase protein and a cardiovascular risk factor. Interleukin-1beta (IL-1beta) and IL-6 stimulate CRP synthesis in hepatocytes. We searched for additional pathways regulating CRP expression. Primary human hepatocytes (PHHs) were treated with IL-1beta, IL-6, and protein kinase C (PKC) activator phorbol 12,13-dibutyrate (PDBu). CRP was analyzed by quantitative RT-PCR and ELISA. PDBu significantly induced CRP transcription by 21.0+/-9.24-fold and protein release by 2.9+/-0.5-fold. Transcriptional regulation was studied in detail in hepatoma G2 (HepG2) cells stably transfected with the 1-kb CRP promoter (HepG2-ABEK14 cells). In these cells, PDBu significantly induced CRP transcription by 5.39+/-0.66-fold. Competitive inhibition with bisindolylmaleimide derivative LY333531 abolished PDBu-mediated promoter activation. Competitive inhibition with IkappaB kinase inhibitor I229 also inhibited PDBu effects. Importantly, IL-8 significantly induced CRP release in PHHs by 58.675+/-19.1-fold, which was blockable by LY333531. This study describes a novel PKC-dependent transcriptional regulation of CRP gene expression, which, in analogy to the classical IL-1beta and IL-6 pathways, is operational in hepatocytes only. It also identifies IL-8 as a potential physiological PKC activator. HepG2-ABEK14 cells may be useful for high throughput screening to identify inhibitors of CRP synthesis for the prevention of cardiovascular disease.

Rapid in vitro conformational changes of the catalytic site of PKC alpha assessed by FIM-1 fluorescence.

To study the activation process of protein kinase C (PKCalpha), we used a fluorescent probe, FIM-1, a bis-indolylmaleimide derivative, which binds to the ATP-binding site on the catalytic domain [Chen, C. S., and Poenie, M. (1993) J. Biol. Chem. 268, 15812]. This enabled us to directly observe the microenvironment of the ATP-binding site in vitro during the activation process. The FIM-1 binding affinity for PKCalpha (EC(50) between 6 and 10 nM) was affected neither by PKCalpha activating conditions nor by enzyme proteolysis. The fluorescence yield of the PKCalpha-FIM-1 complex depended on the PKCalpha activation state. This fluorescence yield was decreased upon proteolysis, which allowed us to study the rate of PKC proteolysis by mu-calpain and its modification by cofactors. Two binding sites were also observed for Ca2+ on the partially activated PKCalpha. After phorbol ester (TPA) application, PKC activation was characterized by biexponential kinetics, including a rapid phase completed within 5 min and a slow phase lasting at least 30 min, which reflected several activation steps. Two different binding sites for TPA were revealed on membrane-associated PKCalpha (EC(50) = 31 +/- 12 and 580 +/- 170 nM), and their modulation by phosphatidylserine and Ca2+ was characterized. The high-affinity TPA binding site was highly conserved, even on the soluble enzyme. Our study shows that binding of low concentrations of TPA triggers conformational changes in the soluble PKCalpha, which affect the microenvironment of its catalytic domain.

Ro31-8220 inhibits protein kinase C to block the phorbol ester-stimulated release of choline- and ethanolamine-metabolites from C6 glioma cells: p70 S6 kinase and MAPKAP kinase-1β do not function downstream of PKC in activating PLD

The use of bisindolylmaleimide derivatives of staurosporine as selective inhibitors of protein kinase C (PKC) is in doubt following the report by Alessi [FEBS Lett. 402 (1997) 121–123] that Ro31-8220 and GF109203X are potent in vitro inhibitors of p70 S6 kinase and mitogen-activated protein kinase-activated protein kinase-1β, as well as of PKC. Here we show that the phorbol ester-stimulated release of choline- and ethanolamine-metabolites from C6 glioma cells due to phospholipid hydrolysis by phospholipase D (PLD) is not inhibited by rapamycin or PD98059, specific inhibitors respectively of p70 S6 kinase and MAPKK (MEK) and thus of MAPKAP kinase-1β but is still completely blocked by Ro31-8220. We conclude therefore that p70 S6k and MAPKAP kinase-1β as well as MAPK are not involved in signalling pathways downstream of PKC that regulate phorbol ester-stimulated phospholipid turnover and that the inhibitory action of Ro31-8220 occurs by blocking PKC which regulates at least one pathway to PLD activation. The PI-3 kinase inhibitor, wortmannin, inhibits the phorbol ester-stimulated release of ethanolamine- but not choline-metabolites from C6 cells suggesting that different PLD isoforms regulate the turnover of PtdEth and PtdCho in C6 cells. Both PLD isoforms are activated via PKC but the PtdEth-PLD is also regulated via a wortmannin-sensitive pathway.