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1.
Cancer Res ; 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31911550

RESUMO

Pancreatic cancer is a disease with limited therapeutic options. Resistance to chemotherapies poses a significant clinical challenge for pancreatic cancer patients and contributes to a high rate of recurrence. Here we showed that oncogenic KRAS, a critical driver of pancreatic cancer, promotes metabolic reprogramming and upregulates NRF2, a master regulator of the antioxidant network. NRF2 contributed to chemoresistance and was associated with a poor prognosis in pancreatic cancer patients. NRF2 activation metabolically rewired and elevated pathways involved in glutamine metabolism. This curbed chemoresistance in KRAS-mutant pancreatic cancers. Additionally, manipulating glutamine metabolism restrained the assembly of stress granules, an indicator of chemoresistance. Glutaminase inhibitors sensitized chemoresistant pancreatic cancer cells to gemcitabine, thereby improving the effectiveness of chemotherapy. This therapeutic approach holds promise as a novel therapy for pancreatic cancer patients harboring KRAS mutation.

2.
Elife ; 92020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31958057

RESUMO

The RAS proteins are GTP-dependent switches that regulate signaling pathways and are frequently mutated in cancer. RAS proteins concentrate in the plasma membrane via lipid-tethers and hypervariable side-chain interactions in distinct nano-domains. However, little is known about RAS membrane dynamics and the details of RAS activation of downstream signaling. Here we characterize RAS in live human and mouse cells using single molecule tracking methods and estimate RAS mobility parameters. KRAS4b exhibits confined mobility with three diffusive states distinct from the other RAS isoforms (KRAS4a, NRAS, and HRAS); and although most of the amino acid differences between RAS isoforms lie within the hypervariable region, the additional confinement of KRAS4b is largely determined by the protein's globular domain. To understand the altered mobility of an oncogenic KRAS4b we used complementary experimental and molecular dynamic simulation approaches to reveal a detailed mechanism.

3.
J Biol Chem ; 295(1): 263-274, 2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31767684

RESUMO

Mammalian target of rapamycin complex 1 (mTORC1) promotes cell growth and proliferation in response to nutrients and growth factors. Amino acids induce lysosomal translocation of mTORC1 via the Rag GTPases. Growth factors activate Ras homolog enriched in brain (Rheb), which in turn activates mTORC1 at the lysosome. Amino acids and growth factors also induce the phospholipase D (PLD)-phosphatidic acid (PA) pathway, required for mTORC1 signaling through mechanisms that are not fully understood. Here, using human and murine cell lines, along with immunofluorescence, confocal microscopy, endocytosis, PLD activity, and cell viability assays, we show that exogenously supplied PA vesicles deliver mTORC1 to the lysosome in the absence of amino acids, Rag GTPases, growth factors, and Rheb. Of note, pharmacological or genetic inhibition of endogenous PLD prevented mTORC1 lysosomal translocation. We observed that precancerous cells with constitutive Rheb activation through loss of tuberous sclerosis complex subunit 2 (TSC2) exploit the PLD-PA pathway and thereby sustain mTORC1 activation at the lysosome in the absence of amino acids. Our findings indicate that sequential inputs from amino acids and growth factors trigger PA production required for mTORC1 translocation and activation at the lysosome.

4.
ACS Appl Mater Interfaces ; 11(50): 47606-47618, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31755256

RESUMO

Finding the most effective method for cancer treatment is one of the thought-provoking tasks. Drug delivery by collapsing of metallogel to the cancer cell is an appealing way out. Cancer cells have an acidic environment due to excessive accumulation of lactic acid. In this work, the novel G5 gelator with a strategically free carboxylic acid arm has been designed and fabricated and characterized by several spectroscopic and microscopic techniques. These experiments suggest the formation of an ordered supramolecular gel with clover-leaf-like morphology. Mechanical properties from rheological measurements suggest the viscoelastic nature of the gel. Furthermore, we have obtained crystals of G5 from the pure dimethyl sulfoxide solution, whereas gelation gets induced by addition of water. This G5 gelator loses its gelation capability once the carboxylate is esterified by layering with methanol, which furnished the crystals of Me-G5' (G5' = G5-H). Further, the G5 gelator is used for the formation of ruthenium metallogel. Interestingly, we obtained the monomeric species [Ru(G5')(η6-p-cymene)Cl] [Ru(II)G5] only in confined gel space upon addition of a [Ru2(η6-p-cymene)2Cl4] dimer to G5. The Ru(II)G5 metallogel has an inherent anticancer property with an IC50 value of 10.53 µM for the A549 cancer cell line. Treatment of the Ru(II)G5 metallogel by lactic acid for mimicking the acidic environment of the malignant cell results in collapsing of the gel by releasing the ruthenium metal ion. This released ruthenium ion binds with the lactic acid derivative making the gelator G5 free and producing a new compound Ru(II)L, which has also shown the anticancer property. The molecular docking study revealed that the released G5 could interact with a monocarboxylate transporter to disrupt the lactate transport chain, which might induce apoptosis.

5.
Inorg Chem ; 58(11): 7324-7334, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31081333

RESUMO

The development of metallogels widens the span of sensing activity as it opens new opportunities to develop chemosensors through metal-ligand interactions. Herein, a new nitrile-substituted 1,3,5-tricarboxamide-based gelator G4 has been fabricated and shows aggregate-induced enhanced emission (AIEE) after gelation in the presence of water. A dimethylformamide (DMF) solution of the gelator shows rapid crystallization, but addition of water to a DMF solution of gelator G4 leads to gelation at room temperature. In addition, gelator G4 was used for the formation of metallogels, and among them, the cobalt metallogel has been found to be effective for sensing l-tryptophan in the gel state through the quenching of AIEE. Interestingly, the gel is also effective in sensing bovine serum albumin protein at the nanomolar level, which contains an l-tryptophan residue. The limit of detection of Co(II)G4 for selective sensing of tryptophan has been found to be 2.4 × 10-8 M. To the best of our knowledge, there have been no reports to date of a metallogel being utilized to discriminate and selectively sense an amino acid and a protein. The gelation properties of the organic gelator molecule and metallogels have been explored through various spectroscopic tools and physicochemical experiments.


Assuntos
Técnicas de Química Analítica/instrumentação , Cobalto/química , Triptofano/análise , Dimetilformamida/química , Modelos Moleculares , Conformação Molecular , Temperatura Ambiente , Fatores de Tempo , Triptofano/química , Água/química
6.
J Inorg Biochem ; 195: 164-173, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30954693

RESUMO

Galactose Oxidase (GOase) and catechol oxidase (COase) are the metalloenzymes of copper having monomeric and dimeric sites of coordination, respectively. This paper summarizes the results of our studies on the structural, spectral and catalytic properties of new mononuclear copper (II) complexes [CuL(OAc)] (1), and [CuL2] (2), (HL = 2,4­dichloro­6­{[(2'­dimethyl­aminoethyl)methylamino]methyl}­phenol) which can mimic the functionalities of the metalloenzymes GOase and COase. The structure of the compounds has been elucidated by X-ray crystallography and the mimicked Cu(II) catalysts were further characterized by EPR. These mimicked models were used for GOase and COase catalysis. The GOase catalytic results were identified by GC-MS and, analyzed by HPLC at room temperature. The conversion of benzyl alcohol to benzaldehyde were significant in presence of a strong base, Bu4NOMe in comparison to the neutral medium. Apart from that, despite of being monomeric in nature, both the homogeneous catalysts are very prone to participate in COase mimicking oxidation reaction. Nevertheless, during COase catalysis, complex 1 was found to convert 3,5­ditertarybutyl catechol (3,5-DTBC) to 3,5­ditertarybutyl quinone (3,5-DTBQ) having greater rate constant, kcat or turn over number (TON) value over complex 2. The generation of reactive intermediates during COase catalysis were accounted by electrospray ionization mass spectrometry (ESI-MS). Through mechanistic approach, we found that H2O2 is the byproduct for both the GOase and COase catalysis, thus, confirming the generation of reactive oxygen species during catalysis. Notably, complex 1 having mono-ligand coordinating atmosphere has superior catalytic activity for both cases in comparison to complex 2, that is having di-ligand environment.

7.
Langmuir ; 34(38): 11575-11585, 2018 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-30168719

RESUMO

Two organogelators G2 and G3 with a carboxamide group have been synthesized and characterized with different spectroscopic tools. Dimethylformamide or dimethyl sulfoxide solutions of both the compounds upon the addition of a minute quantity of water show the tendency to form gels. Supramolecular self-assembly for gel formation paves the way for aggregation-induced emission enhancement (AIEE) phenomena for both the gelator molecules. Introduction of metal ions in organogels strengthens the gel property without much affecting the fluorescence behavior. However, the introduction of Ag+, Fe2+, and Fe3+ ions in the G2 organogel separately results in total quenching of AIEE, making it possible to sense that particular cation in the gel state. The G3 organogel shows a similar behavior with the Fe2+ ion. Remarkably, other metallogels such as Ni(II)G2 and Co(II)G2 can sense sulfide ion and Cu(II)G2 can sense iodide ion by switching off the fluorescence even in multianalyte conditions. Furthermore, the copper-based metallogel Cu(II)G2 can be utilized as a catalyst and reaction medium for aerobic oxidation of catechol to quinone. To the best of our knowledge, this is the first attempt known so far to utilize a metallogel material for bioinspired catalysis such as catechol oxidation.

8.
Dalton Trans ; 47(2): 517-527, 2018 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-29235601

RESUMO

Non-steroidal anti-inflammatory drugs (NSAIDs) are a group of molecules which have been found to be active against cancer cells with chemopreventive properties by targeting cyclooxygenase (COX-1 and COX-2) and lipoxygenase (LOX), commonly upregulated (particularly COX-2) in malignant tumors. Arene ruthenium(ii) complexes with a pseudo-octahedral coordination environment containing different ancillary ligands have shown remarkable activity against primary and metastatic tumors as reported earlier. This work describes the synthesis of four novel ruthenium(ii)-arene complexes viz. [Ru(η6-p-cymene)(nap)Cl] 1 [Hnap = naproxen or (S)-2-(6-methoxy-2-naphthyl)propionic acid], [Ru(η6-p-cymene)(diclo)Cl] 2 [Hdiclo = diclofenac or 2-[(2,6-dichlorophenyl)amino] benzeneacetic acid, [Ru(η6-p-cymene)(ibu)Cl] 3 [Hibu = ibuprofen or 2-(4-isobutylphenyl)propanoic acid] and [Ru(η6-p-cymene)(asp)Cl] 4 [Hasp = aspirin or 2-acetoxy benzoic acid] using different NSAIDs as chelating ligands. Complexes 1-3 have shown promising antiproliferative activity against three different cell lines with GI50 (concentration of drug causing 50% inhibition of cell growth) values comparable to adriamycin. At the concentration of 50 µM, complex 3 is more effective in the inhibition of cyclooxygenase and lipooxygenase enzymes, followed by complex 2 and complex 1 in comparison to their respective free NSAID ligands indicating a possible correlation between the inhibition of COX and/or LOX and anticancer properties. Molecular docking studies with COX-2 reveal that complexes 1 and 2 having naproxen and diclofenac ligands exhibit stronger interactions with COX-2 than their respective free NSAIDs and these results are in good agreement with their relative experimentally observed COX inhibition as well as anti-proliferative activities.


Assuntos
Anti-Inflamatórios não Esteroides/química , Benzeno/química , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Prostaglandina-Endoperóxido Sintases/metabolismo , Rutênio/química , Animais , Bovinos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ciclo-Oxigenase 1/química , Ciclo-Oxigenase 1/metabolismo , Ciclo-Oxigenase 2/química , Ciclo-Oxigenase 2/metabolismo , Inibidores de Ciclo-Oxigenase/síntese química , Inibidores de Ciclo-Oxigenase/química , Inibidores de Ciclo-Oxigenase/metabolismo , Inibidores de Ciclo-Oxigenase/farmacologia , DNA/metabolismo , Dimetil Sulfóxido/química , Estabilidade de Medicamentos , Humanos , Lipoxigenase/metabolismo , Inibidores de Lipoxigenase/síntese química , Inibidores de Lipoxigenase/química , Inibidores de Lipoxigenase/metabolismo , Inibidores de Lipoxigenase/farmacologia , Simulação de Acoplamento Molecular , Compostos Organometálicos/síntese química , Compostos Organometálicos/metabolismo , Prostaglandina-Endoperóxido Sintases/química , Conformação Proteica , Soroalbumina Bovina/metabolismo
9.
Soft Matter ; 13(36): 6243-6249, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-28808713

RESUMO

A carboxamide based molecule has shown unique gelation property in an aqueous mixture of DMF or DMSO. The gel itself has shown aggregation-induced fluorescence enhanced emission (AIEE), which can be utilized effectively in sensing ferrous and ferric ions as both of them switch off the fluorescence completely. An investigation by IR spectroscopy reveals an enhanced π interaction of nitrile group with the iron center and this could be the possible reason behind the complete quenching of AIEE. This molecule was further investigated for the formation of metallogels for a wide array of cations, which in turn can act in tandem to behave as a dynamic array to detect several anions by either switching off or switching on the emission property of the metallogels.

10.
Dalton Trans ; 45(48): 19277-19289, 2016 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-27868122

RESUMO

Four new ruthenium arene PTA type complexes have been synthesized using substituted picolinamide derivatives as ancillary ligands and characterized by spectroscopic methods. In one of the complexes, the ancillary ligand has shown an unprecedented valence-bond tautomerization in the presence of an ammonium salt to act as a polar neutral donor ligand making the ligand more prone towards substitution. The same compound has shown remarkable antiproliferative activity against three cancer cell lines with GI50 values comparable to Adriamycin, a known therapeutic drug. Along with this it also strongly inhibits the action of thioredoxin reductase, which might be a probable reason for the enhanced proliferative action of the valence-bond tautomerized compound.


Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Inibidores Enzimáticos/farmacologia , Rutênio/química , Antineoplásicos/química , Complexos de Coordenação/química , Cristalografia por Raios X , Inibidores Enzimáticos/química , Isomerismo , Ligantes , Espectroscopia de Prótons por Ressonância Magnética , Espectrometria de Massas por Ionização por Electrospray
11.
PLoS One ; 11(6): e0157532, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27362507

RESUMO

The quorum sensing molecule Autoinducer-2 (AI-2) is generated as a byproduct of activated methyl cycle by the action of LuxS in Escherichia coli. AI-2 is synthesized, released and later internalized in a cell-density dependent manner. Here, by mutational analysis of the genes, uvrY and csrA, we describe a regulatory circuit of accumulation and uptake of AI-2. We constructed a single-copy chromosomal luxS-lacZ fusion in a luxS + merodiploid strain and evaluated its relative expression in uvrY and csrA mutants. At the entry of stationary phase, the expression of the fusion and AI-2 accumulation was positively regulated by uvrY and negatively regulated by csrA respectively. A deletion of csrA altered message stability of the luxS transcript and CsrA protein exhibited weak binding to 5' luxS regulatory region. DNA protein interaction and chromatin immunoprecipitation analysis confirmed direct interaction of UvrY with the luxS promoter. Additionally, reduced expression of the fusion in hfq deletion mutant suggested involvement of small RNA interactions in luxS regulation. In contrast, the expression of lsrA operon involved in AI-2 uptake, is negatively regulated by uvrY and positively by csrA in a cell-density dependent manner. The dual role of csrA in AI-2 synthesis and uptake suggested a regulatory crosstalk of cell signaling with carbon regulation in Escherichia coli. We found that the cAMP-CRP mediated catabolite repression of luxS expression was uvrY dependent. This study suggests that luxS expression is complex and regulated at the level of transcription and translation. The multifactorial regulation supports the notion that cell-cell communication requires interaction and integration of multiple metabolic signals.


Assuntos
Comunicação Celular/fisiologia , Escherichia coli/metabolismo , Homosserina/análogos & derivados , Lactonas/metabolismo , Carbono/metabolismo , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Homosserina/metabolismo , Regiões Promotoras Genéticas
12.
Mol Cancer Ther ; 15(3): 347-53, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26916116

RESUMO

The mTOR pathway is a critical regulator of cell growth, proliferation, metabolism, and survival. Dysregulation of mTOR signaling has been observed in most cancers and, thus, the mTOR pathway has been extensively studied for therapeutic intervention. Rapamycin is a natural product that inhibits mTOR with high specificity. However, its efficacy varies by dose in several contexts. First, different doses of rapamycin are needed to suppress mTOR in different cell lines; second, different doses of rapamycin are needed to suppress the phosphorylation of different mTOR substrates; and third, there is a differential sensitivity of the two mTOR complexes mTORC1 and mTORC2 to rapamycin. Intriguingly, the enigmatic properties of rapamycin dosage can be explained in large part by the competition between rapamycin and phosphatidic acid (PA) for mTOR. Rapamycin and PA have opposite effects on mTOR whereby rapamycin destabilizes and PA stabilizes both mTOR complexes. In this review, we discuss the properties of rapamycin dosage in the context of anticancer therapeutics.


Assuntos
Antibióticos Antineoplásicos/administração & dosagem , Neoplasias/tratamento farmacológico , Inibidores de Proteínas Quinases/administração & dosagem , Sirolimo/administração & dosagem , Animais , Antibióticos Antineoplásicos/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina , Alvo Mecanístico do Complexo 2 de Rapamicina , Complexos Multiproteicos/antagonistas & inibidores , Complexos Multiproteicos/metabolismo , Neoplasias/metabolismo , Ligação Proteica , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/química , Serina-Treonina Quinases TOR/metabolismo
14.
Dalton Trans ; 44(46): 20154-67, 2015 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-26530012

RESUMO

Two new mononuclear water soluble copper(II) complexes, [Cu{(5-pyrazinyl)tetrazolate}2(1,10-phenanthroline)] 1 and [Cu{(5-pyrazinyl)tetrazolate}(1,10-phenanthroline)2](NO3)0.5(N3)0.5 2, have been synthesized using the metal mediated [2 + 3] cycloaddition reaction between copper bound azide and pyrazinecarbonitrile. The interactions of these copper tetrazolate complexes 1 and 2 with biomolecules like DNA and bovine serum albumin (BSA) are studied and the catecholase like catalytic activity of compound 2 is also explored. Structural determination reveals that both compounds 1 and 2 are octahedral in nature. Screening tests were conducted to quantify the binding ability of complexes (1 and 2) towards DNA and it was revealed that complex 2 has a stronger affinity to bind to CT-DNA. DFT studies indicated that a lower HOMO-LUMO energy gap between the DNA fragment and metal complexes might be the reason for this type of stronger interaction. DNA cleavage activity was explored by gel-electrophoresis and moderate to strong DNA cleavage properties were observed in the presence and absence of co-reagents. Inhibition of cleavage in the presence of sodium azide indicates the propagation of the activity through the production of singlet molecular oxygen. Furthermore enzyme kinetic studies reflect that complex 2 is also effective in mimicking catecholase like activities. An ESI-MS spectral study indicates the probable involvement of dimeric species [(phen)2Cu-(OH)2-Cu(phen)2](2+) in the catalytic cycle.


Assuntos
Catecol Oxidase/química , Complexos de Coordenação/química , Cobre/química , Clivagem do DNA/efeitos dos fármacos , Tetrazóis/química , Animais , Catálise , Catecol Oxidase/farmacologia , Bovinos , Complexos de Coordenação/farmacologia , Cobre/farmacologia , Cristalografia por Raios X , DNA/química , Cinética , Modelos Moleculares , Oxirredução , Fenantrolinas/química , Fenantrolinas/farmacologia , Soroalbumina Bovina/química , Solubilidade , Tetrazóis/farmacologia , Água/química
15.
Molecules ; 20(10): 19203-20, 2015 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-26506333

RESUMO

Microwave assisted synthesis of the Cu(I) compound [Cu(µ4-4-ptz)]n [1, 4-ptz=5-(4-pyridyl)tetrazolate] has been performed by employing a relatively easy method and within a shorter period of time compared to its sister compounds. The syntheses of the Cu(II) compounds [Cu3(µ3-4-ptz)4(µ2-N3)2(DMF)2]n∙(DMF)2n (2) and [Cu(µ2-4-ptz)2(H2O)2]n (3) using a similar method were reported previously by us. MOFs 1-3 revealed high catalytic activity toward oxidation of cyclic alkanes (cyclopentane, -hexane and -octane) with aqueous hydrogen peroxide, under very mild conditions (at room temperature), without any added solvent or additive. The most efficient system (2/H2O2) showed, for the oxidation of cyclohexane, a turnover number (TON) of 396 (TOF of 40 h(-1)), with an overall product yield (cyclohexanol and cyclohexanone) of 40% relative to the substrate. Moreover, the heterogeneous catalytic systems 1-3 allowed an easy catalyst recovery and reuse, at least for four consecutive cycles, maintaining ca. 90% of the initial high activity and concomitant high selectivity.


Assuntos
Cobre/química , Cicloexanóis/síntese química , Cicloexanonas/síntese química , Peróxido de Hidrogênio/química , Compostos Organometálicos/química , Catálise , Cicloexanos/química , Química Verde , Micro-Ondas , Oxirredução
16.
Cell Cycle ; 14(20): 3331-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26323019

RESUMO

mTOR - the mammalian/mechanistic target of rapamycin - has been implicated as a key signaling node for promoting survival of cancer cells. However, clinical trials that have targeted mTOR with rapamycin or rapamycin analogs have had minimal impact. In spite of the high specificity of rapamycin for mTOR, the doses needed to suppress key mTOR substrates have proved toxic. We report here that rapamycin when combined with AICAR - a compound that activates AMP-activated protein kinase makes rapamycin cytotoxic rather than cytostatic at doses that are tolerated clinically. AICAR by itself is able to suppress mTOR complex 1 (mTORC1), but also stimulates a feedback activation of mTORC2, which activates the survival kinase Akt. However, AICAR also suppresses production of phosphatidic acid (PA), which interacts with mTOR in a manner that is competitive with rapamycin. The reduced level of PA sensitizes mTORC2 to rapamycin at tolerable nano-molar doses leading reduced Akt phosphorylation and apoptosis. This study reveals how the use of AICAR enhances the efficacy of rapamycin such that rapamycin at low nano-molar doses can suppress mTORC2 and induce apoptosis in human cancer cells at doses that are clinically tolerable.


Assuntos
Aminoimidazol Carboxamida/análogos & derivados , Neoplasias/metabolismo , Neoplasias/patologia , Ribonucleotídeos/administração & dosagem , Sirolimo/administração & dosagem , Aminoimidazol Carboxamida/administração & dosagem , Antibióticos Antineoplásicos/administração & dosagem , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/fisiologia , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/fisiologia , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Humanos , Células MCF-7 , Neoplasias/tratamento farmacológico , Resultado do Tratamento
17.
Cell Cycle ; 14(14): 2285-92, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25945415

RESUMO

Mutations in genes encoding regulators of mTOR, the mammalian target of rapamycin, commonly provide survival signals in cancer cells. Rapamycin and analogs of rapamycin have been used with limited success in clinical trials to target mTOR-dependent survival signals in a variety of human cancers. Suppression of mTOR predominantly causes G1 cell cycle arrest, which likely contributes to the ineffectiveness of rapamycin-based therapeutic strategies. While rapamycin causes the accumulation of cells in G1, its effect in other cell cycle phases remains largely unexplored. We report here that when synchronized MDA-MB-231 breast cancer cells are allowed to progress into S-phase from G1, rapamycin activates the apoptotic machinery with a concomitant increase in cell death. In Calu-1 lung cancer cells, rapamycin induced a feedback increase in Akt phosphorylation at Ser473 in S-phase that mitigated rapamycin-induced apoptosis. However, sensitivity to rapamycin in S-phase could be reestablished if Akt phosphorylation was suppressed. We recently reported that glutamine (Gln) deprivation causes K-Ras mutant cancer cells to aberrantly arrest primarily in S-phase. Consistent with observed sensitivity of S-phase cells to rapamycin, interfering with Gln utilization sensitized both MDA-MB-231 and Calu-1 K-Ras mutant cancer cells to the apoptotic effect of rapamycin. Importantly, rapamycin induced substantially higher levels of cell death upon Gln depletion than that observed in cancer cells that were allowed to progress through S-phase after being synchronized in G1. We postulate that exploiting metabolic vulnerabilities in cancer cells such as S-phase arrest observed with K-Ras-driven cancer cells deprived of Gln, could be of great therapeutic potential.


Assuntos
Apoptose/efeitos dos fármacos , Sirolimo/farmacologia , Linhagem Celular Tumoral , Cromonas/farmacologia , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Humanos , Células MCF-7 , Morfolinas/farmacologia , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fase S , Pontos de Checagem da Fase S do Ciclo Celular/efeitos dos fármacos , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Proteínas ras/metabolismo
18.
Cancer Lett ; 360(2): 134-40, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25659819

RESUMO

The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of G1 cell cycle progression. Two key substrates of mTORC1 are ribosomal subunit S6 kinase (S6K) and eukaryotic initiation factor 4E (eIF4E) binding protein-1 (4E-BP1). We reported previously that simultaneous knockdown of S6K and eIF4E causes a transforming growth factor-ß (TGF-ß)-dependent G1 cell cycle arrest in MDA-MB-231 human breast cancer cells. Rapamycin inhibits the phosphorylation of S6K at nano-molar concentrations in MDA-MB-231 cells; however, micro-molar concentrations of rapamycin are required to inhibit phosphorylation of 4E-BP1 - the phosphorylation of which liberates eIF4E to initiate translation. Micro-molar doses of rapamycin are required for complete G1 cell cycle arrest - indicating that 4E-BP1 is a critical target of mTOR for promoting cell cycle progression. Data are provided demonstrating that G1 cell cycle arrest induced by rapamycin is due to up-regulation of TGF-ß signaling and down-regulation of Rb phosphorylation via phosphorylation of the mTORC1 substrates S6K and 4E-BP1 respectively. These findings enhance the current understanding of the cytostatic effects of mTORC1 suppression with therapeutic implications.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Proteína do Retinoblastoma/metabolismo , Sirolimo/farmacologia , Fator de Crescimento Transformador beta/metabolismo , Antibióticos Antineoplásicos/farmacologia , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Ciclina D1/antagonistas & inibidores , Ciclina D1/biossíntese , Relação Dose-Resposta a Droga , Feminino , Pontos de Checagem da Fase G1 do Ciclo Celular/fisiologia , Humanos , Células MCF-7 , Fosforilação
19.
J Biol Chem ; 290(11): 6986-93, 2015 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-25632961

RESUMO

AMP-activated protein kinase (AMPK), a critical sensor of energy sufficiency, acts as central metabolic switch in cell metabolism. Once activated by low energy status, AMPK phosphorylates key regulatory substrates and turns off anabolic biosynthetic pathways. In contrast, the mammalian/mechanistic target of rapamycin (mTOR) is active when there are sufficient nutrients for anabolic reactions. A critical factor regulating mTOR is phosphatidic acid (PA), a central metabolite of membrane lipid biosynthesis and the product of the phospholipase D (PLD)-catalyzed hydrolysis of phosphatidylcholine. PLD is a downstream target of the GTPase Rheb, which is turned off in response to AMPK via the tuberous sclerosis complex. Although many studies have linked AMPK with mTOR, very little is known about the connection between AMPK and PLD. In this report, we provide evidence for reciprocal regulation of PLD by AMPK and regulation of AMPK by PLD and PA. Suppression of AMPK activity led to an increase in PLD activity, and conversely, activation of AMPK suppressed PLD activity. Suppression of PLD activity resulted in elevated AMPK activity. Exogenously supplied PA abolished the inhibitory effects of elevated AMPK activity on mTOR signaling. In contrast, exogenously supplied PA could not overcome the effect AMPK activation if either mTOR or Raptor was suppressed, indicating that the inhibitory effects of PLD and PA on AMPK activity are mediated by mTOR. These data suggest a reciprocal feedback mechanism involving AMPK and the PLD/mTOR signaling node in cancer cells with therapeutic implications.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Neoplasias/enzimologia , Fosfolipase D/metabolismo , Linhagem Celular Tumoral , Ativação Enzimática , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina , Complexos Multiproteicos/metabolismo , Neoplasias/metabolismo , Ácidos Fosfatídicos/metabolismo , Serina-Treonina Quinases TOR/metabolismo
20.
Dalton Trans ; 44(5): 2299-310, 2015 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-25531802

RESUMO

Four new mononuclear Ni(ii) complexes [Ni(L(1))]ClO4 (), [Ni(L(2))]ClO4(), [Ni(SCN)3(CH3OH)(aminoethylpiperazineH)] (), and [Ni(DMSO)4(aminoethylpiperazineH)](ClO4)3()have been synthesized from two Schiff base ligands [L(1) = 1-phenyl-3-((2-(piperidin-4-yl)ethyl)imino)but-1-en-1-ol and L(2) = 4-((2-(piperazin-1-yl)ethyl)imino)pent-2-en-2-ol] by exploiting the flexibility of the piperazinyl moiety. Structural analysis reveals that and are square planar complexes with piperazine rings in boat conformations whereas hydrolysis of Schiff bases (L(1) and L(2)) occurs during formation of octahedral complexes ( and ) with piperazine rings in chair conformations. Screening tests were conducted to quantify the binding ability of complexes (, and ) towards DNA, BSA and HSA and it was found that square planar complexes ( and ) showed more effective binding properties over octahedral complex (). Furthermore, enzyme kinetic studies reflect that square planar complexes ( and ) are also effective in mimicking catecholase like activities over octahedral complex (). Among all the complexes, was found to be the most promising molecule among the series due to its large binding affinity towards different bio-macromolecules and higher T.O.N in the catechol oxidation reaction.


Assuntos
DNA/metabolismo , Níquel/química , Compostos Organometálicos/química , Compostos Organometálicos/metabolismo , Oxirredutases/metabolismo , Piperazinas/química , Albumina Sérica/metabolismo , Animais , Materiais Biomiméticos/química , Materiais Biomiméticos/metabolismo , Catecóis/metabolismo , Bovinos , Humanos , Modelos Moleculares , Conformação Molecular , Piperazina , Ligação Proteica , Bases de Schiff/química
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