Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
1.
Toxicol Mech Methods ; 25(1): 56-62, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25496143

RESUMO

Mycotoxins are naturally occurring contaminants encountered at high levels in a wide variety of agricultural products intended for human and animal consumptions. Various Alternaria mycotoxins may occur simultaneously in small grain cereals. Considering the concomitant production of alternariol (AOH) and alternariol monomethyl ether (AME), it is expected that humans and animals are exposed to the mixture rather than to individual compounds. Therefore, we studied the interactive effects of binary mixture of alternariols (AOH and AME) on the human intestinal cell line, HCT116 cells. Exposure of HCT116 cells to low cytotoxic alternariols doses, resulted in a moderate cytotoxicity manifested by a loss in the cell viability mediated by an activation of the mitochondrial apoptotic process, associated with the opening of mitochondrial permeability transition pore (PTP) and the loss of the mitochondrial transmembrane potential (ΔΨm). However, when combined, they exert a significant increase in their toxic potential. Altogether, our study showed that AOH and AME combination is obviously additive.


Assuntos
Neoplasias do Colo/patologia , Lactonas/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Neoplasias do Colo/metabolismo , Relação Dose-Resposta a Droga , Células HCT116 , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Proteínas de Transporte da Membrana Mitocondrial/efeitos dos fármacos , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Medição de Risco , Fatores de Tempo
2.
Biochim Biophys Acta ; 1833(6): 1356-66, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23485394

RESUMO

Heat shock protein 90 (Hsp90) has recently emerged as an attractive therapeutic target in cancer treatment because of its role in stabilizing the active form of a wide range of client oncoproteins. This study investigated the mechanism of apoptosis induced by the purine-scaffold Hsp90 inhibitor PU-H71 in different human cancer cell lines and examined the role of Bcl-2 and Bax in this process. We demonstrated that Hsp90 inhibition by PU-H71 generated endoplasmic reticulum (ER) stress and activated the Unfolded Protein Response (UPR) as evidenced by XBP1 mRNA splicing and up-regulation of Grp94, Grp78, ATF4 and CHOP. In response to PU-H71-induced ER stress, apoptosis was triggered in melanoma, cervix, colon, liver and lung cancer cells, but not in normal human fibroblasts. Apoptosis was executed through the mitochondrial pathway as shown by down-regulation of Bcl-2, up-regulation and activation of Bax, permeabilization of mitochondrial membranes, release of cytochrome c and activation of caspases. We also found that, in contrast to the ER stressor thapsigargin, PU-H71 induced apoptosis in cells overexpressing Bcl-2 and thus overcame the resistance conferred by this anti-apoptotic protein. In addition, although Bax deficiency rendered cells resistant to PU-H71, combined treatment with the anticancer drugs cisplatin or melphalan greatly sensitized these cells to PU-H71. Taken together, these data suggest that inhibition of Hsp90 by PU-H71 is a promising strategy for cancer treatment, particularly in the case of tumors resistant to conventional chemotherapy.


Assuntos
Apoptose/efeitos dos fármacos , Benzodioxóis/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Neoplasias/patologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Purinas/farmacologia , Antineoplásicos/farmacologia , Antineoplásicos Alquilantes/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica , Western Blotting , Caspases/metabolismo , Proliferação de Células/efeitos dos fármacos , Cisplatino/farmacologia , Chaperona BiP do Retículo Endoplasmático , Inibidores Enzimáticos/farmacologia , Citometria de Fluxo , Imunofluorescência , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Humanos , Melfalan/farmacologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Tapsigargina/farmacologia , Células Tumorais Cultivadas , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Proteína X Associada a bcl-2/metabolismo
3.
Cell Death Discov ; 9(1): 230, 2023 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-37414800

RESUMO

Toll-like receptor 3 (TLR3) is a pattern recognition receptor mainly known for its role in innate immune response to infection. Indeed, binding of double-stranded RNA (dsRNA) to TLR3 triggers a pro-inflammatory cascade leading to cytokine release and immune cell activation. Its anti-tumoral potential has emerged progressively, associated with a direct impact on tumor cell death induction and with an indirect action on immune system reactivation. Accordingly, TLR3 agonists are currently being tested in clinical trials for several adult cancers. Meanwhile, TLR3 variants have been linked to auto-immune disorders, and as risk factors of viral infection and cancers. However, aside from neuroblastoma, TLR3 role in childhood cancers has not been evaluated. Here, by integrating public transcriptomic data of pediatric tumors, we unveil that high TLR3 expression is largely associated with a better prognosis in childhood sarcomas. Using osteosarcomas and rhabdomyosarcomas as models, we show that TLR3 efficiently drives tumor cell death in vitro and induces tumor regression in vivo. Interestingly, this anti-tumoral effect was lost in cells expressing the homozygous TLR3 L412F polymorphism, which is enriched in a rhabdomyosarcomas cohort. Thus, our results demonstrate the therapeutic potential associated with the targeting of TLR3 in pediatric sarcomas, but also the need to stratify patients eligible for this clinical approach with respect to the TLR3 variants expressed.

4.
Apoptosis ; 16(10): 1014-27, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21710254

RESUMO

A high resistance and heterogeneous response to conventional anti-cancer chemotherapies characterize malignant cutaneous melanoma, the most aggressive and deadly form of skin cancer. Withaferin A (WFA), a withanolide derived from the medicinal plant Withania somnifera, has been reported for its anti-tumorigenic activity against various cancer cells. For the first time, we examined the death-inducing potential of WFA against a panel of four different human melanoma cells and investigated the cellular mechanisms involved. WFA induces apoptotic cell death with various IC50 ranging from 1.8 to 6.1 µM. The susceptibility of cells toward WFA-induced apoptosis correlated with low Bcl-2/Bax and Bcl-2/Bim ratios. In all cell lines, the apoptotic process triggered by WFA involves the mitochondrial pathway and was associated with Bcl-2 down regulation, Bax mitochondrial translocation, cytochrome c release into the cytosol, transmembrane potential (ΔΨm) dissipation, caspase 9 and caspase 3 activation and DNA fragmentation. WFA cytotoxicity requires early reactive oxygen species (ROS) production and glutathione depletion, the inhibition of ROS increase by the antioxidant N-acetylcysteine resulting in complete suppression of mitochondrial and nuclear events. Altogether, these results support the therapeutic potential of WFA against human melanoma.


Assuntos
Apoptose/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Vitanolídeos/farmacologia , Proteína X Associada a bcl-2/metabolismo , Animais , Caspase 3/metabolismo , Caspase 9/metabolismo , Linhagem Celular Tumoral , Fragmentação do DNA/efeitos dos fármacos , Regulação para Baixo , Humanos , Melanoma/tratamento farmacológico , Melanoma/patologia , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Vitanolídeos/uso terapêutico
5.
Sci Adv ; 7(1)2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33523852

RESUMO

Unbalanced energy partitioning participates in the rise of obesity, a major public health concern in many countries. Increasing basal energy expenditure has been proposed as a strategy to fight obesity yet raises efficiency and safety concerns. Here, we show that mice deficient for a muscle-specific enzyme of very-long-chain fatty acid synthesis display increased basal energy expenditure and protection against high-fat diet-induced obesity. Mechanistically, muscle-specific modulation of the very-long-chain fatty acid pathway was associated with a reduced content of the inner mitochondrial membrane phospholipid cardiolipin and a blunted coupling efficiency between the respiratory chain and adenosine 5'-triphosphate (ATP) synthase, which was restored by cardiolipin enrichment. Our study reveals that selective increase of lipid oxidative capacities in skeletal muscle, through the cardiolipin-dependent lowering of mitochondrial ATP production, provides an effective option against obesity at the whole-body level.

6.
Int J Cell Biol ; 2019: 9151394, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31360169

RESUMO

Renal tubulointerstitial fibrosis is the final common pathway in end-stage renal disease and is characterized by aberrant accumulation of extracellular matrix (ECM) components secreted by myofibroblasts. Tubular type 2 EMT, induced by TGF-ß, plays an important role in renal fibrosis, by participating directly or indirectly in myofibroblasts generation. TGF-ß1-induced apoptosis and fibrosis in experimental chronic murine kidney diseases are concomitantly associated with an intrarenal decreased expression of the IL-15 survival factor. Since IL-15 counteracts TGF-ß1 effects in different cell models, we analyzed whether (1) human chronic inflammatory nephropathies evolving towards fibrosis could be also characterized by a weak intrarenal IL-15 expression and (2) IL-15 could inhibit epithelial-mesenchymal transition (EMT) and excess matrix deposition in human renal proximal tubular epithelial cells (RPTEC). Our data show that different human chronic kidney diseases are characterized by a strong decreased expression of intrarenal IL-15, which is particularly relevant in diabetic nephropathy, in which type 2 tubular EMT plays an important role in fibrosis. Moreover, primary epithelial tubular cultures deprived of growth supplements rapidly produce active TGF-ß1 inducing a "spontaneous" EMT process characterized by the loss of membrane-bound IL-15 (mbIL-15) expression. Both "spontaneous" EMT and recombinant human (rh) TGF-ß1-induced EMT models can be inhibited by treating RPTEC and HK2 cells with rhIL-15. Through a long-lasting phospho-c-jun activation, IL-15 inhibits rhTGF-ß1-induced Snail1 expression, the master inducer of EMT, and blocks TGF-ß1-induced tubular EMT and downstream collagen synthesis. In conclusion, our data suggest that intrarenal IL-15 could be a natural inhibitor of TGF-ß in human kidney able to guarantee epithelial homeostasis and to prevent EMT process. Thus, both in vivo and in vitro an unbalance in intrarenal IL-15 and TGF-ß1 levels could render RPTEC cells more prone to undergo EMT process. Exogenous IL-15 treatment could be beneficial in some human nephropathies such as diabetic nephropathy.

7.
Cell Death Differ ; 24(2): 343-356, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27911441

RESUMO

Over the past decade, endoplasmic reticulum (ER) stress has emerged as an important mechanism involved in the pathogenesis of cardiovascular diseases including heart failure. Cardiac therapy based on ER stress modulation is viewed as a promising avenue toward effective therapies for the diseased heart. Here, we tested whether sirtuin-1 (SIRT1), a NAD+-dependent deacetylase, participates in modulating ER stress response in the heart. Using cardiomyocytes and adult-inducible SIRT1 knockout mice, we demonstrate that SIRT1 inhibition or deficiency increases ER stress-induced cardiac injury, whereas activation of SIRT1 by the SIRT1-activating compound STAC-3 is protective. Analysis of the expression of markers of the three main branches of the unfolded protein response (i.e., PERK/eIF2α, ATF6 and IRE1) showed that SIRT1 protects cardiomyocytes from ER stress-induced apoptosis by attenuating PERK/eIF2α pathway activation. We also present evidence that SIRT1 physically interacts with and deacetylates eIF2α. Mass spectrometry analysis identified lysines K141 and K143 as the acetylation sites on eIF2α targeted by SIRT1. Furthermore, mutation of K143 to arginine to mimic eIF2α deacetylation confers protection against ER stress-induced apoptosis. Collectively, our findings indicate that eIF2α deacetylation on lysine K143 by SIRT1 is a novel regulatory mechanism for protecting cardiac cells from ER stress and suggest that activation of SIRT1 has potential as a therapeutic approach to protect the heart against ER stress-induced injury.


Assuntos
Apoptose , Estresse do Retículo Endoplasmático , Fator de Iniciação 2 em Eucariotos/metabolismo , Sirtuína 1/metabolismo , Acetilação , Fator 6 Ativador da Transcrição/metabolismo , Animais , Apoptose/efeitos dos fármacos , Carbazóis/farmacologia , Linhagem Celular , Chaperona BiP do Retículo Endoplasmático , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Fator de Iniciação 2 em Eucariotos/genética , Proteínas de Choque Térmico/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutagênese Sítio-Dirigida , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Ligação Proteica , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sirtuína 1/antagonistas & inibidores , Sirtuína 1/genética , Tunicamicina/farmacologia , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
8.
Oncotarget ; 7(50): 82511-82527, 2016 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-27764776

RESUMO

Melanoma is a particularly virulent human cancer, due to its resistance to conventional treatments and high frequency of metastasis. Melanomas contain a fraction of cells, the melanoma-initiating cells (MICs), responsible for tumor propagation and relapse. Identification of the molecular pathways supporting MICs is, therefore, vital for the development of targeted treatments. One factor produced by melanoma cells and their microenvironment, insulin-like growth factor-1 (IGF- 1), is linked to epithelial-mesenchymal transition (EMT) and stemness features in several cancers.We evaluated the effect of IGF-1 on the phenotype and chemoresistance of B16-F10 cells. IGF-1 inhibition in these cells prevented malignant cell proliferation, migration and invasion, and lung colony formation in immunodeficient mice. IGF-1 downregulation also markedly inhibited EMT, with low levels of ZEB1 and mesenchymal markers (N-cadherin, CD44, CD29, CD105) associated with high levels of E-cadherin and MITF, the major regulator of melanocyte differentiation. IGF-1 inhibition greatly reduced stemness features, including the expression of key stem markers (SOX2, Oct-3/4, CD24 and CD133), and the functional characteristics of MICs (melanosphere formation, aldehyde dehydrogenase activity, side population). These features were associated with a high degree of sensitivity to mitoxantrone treatment.In this study, we deciphered new connections between IGF-1 and stemness features and identified IGF-1 as instrumental for maintaining the MIC phenotype. The IGF1/IGF1-R nexus could be targeted for the development of more efficient anti-melanoma treatments. Blocking the IGF-1 pathway would improve the immune response, decrease the metastatic potential of tumor cells and sensitize melanoma cells to conventional treatments.


Assuntos
Biomarcadores Tumorais/metabolismo , Proliferação de Células , Transição Epitelial-Mesenquimal , Fator de Crescimento Insulin-Like I/metabolismo , Melanoma Experimental/metabolismo , Células-Tronco Neoplásicas/metabolismo , Neoplasias Cutâneas/metabolismo , Animais , Antineoplásicos/farmacologia , Biomarcadores Tumorais/genética , Linhagem Celular Tumoral , Movimento Celular , Resistencia a Medicamentos Antineoplásicos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Feminino , Fator de Crescimento Insulin-Like I/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/prevenção & controle , Neoplasias Pulmonares/secundário , Melanoma Experimental/tratamento farmacológico , Melanoma Experimental/genética , Melanoma Experimental/secundário , Camundongos Endogâmicos C57BL , Mitoxantrona/farmacologia , Invasividade Neoplásica , Células-Tronco Neoplásicas/patologia , Células-Tronco Neoplásicas/efeitos da radiação , Transdução de Sinais , Neoplasias Cutâneas/tratamento farmacológico , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Fatores de Tempo , Transfecção , Microambiente Tumoral
9.
Oncotarget ; 7(13): 15507-24, 2016 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-26551931

RESUMO

As rapidly developing patient-derived xenografts (PDX) could represent potential sources of cancer stem cells (CSC), we selected and characterized non-cultured PDX cell suspensions from four different renal carcinomas (RCC). Only the cell suspensions from the serial xenografts (PDX-1 and PDX-2) of an undifferentiated RCC (RCC-41) adapted to the selective CSC medium. The cell suspension derived from the original tumor specimen (RCC-41-P-0) did not adapt to the selective medium and strongly expressed CSC-like markers (CD133 and CD105) together with the non-CSC tumor marker E-cadherin. In comparison, PDX-1 and PDX-2 cells exhibited evolution in their phenotype since PDX-1 cells were CD133high/CD105-/Ecadlow and PDX-2 cells were CD133low/CD105-/Ecad-. Both PDX subsets expressed additional stem cell markers (CD146/CD29/OCT4/NANOG/Nestin) but still contained non-CSC tumor cells. Therefore, using different cell sorting strategies, we characterized 3 different putative CSC subsets (RCC-41-PDX-1/CD132+, RCC-41-PDX-2/CD133-/EpCAMlow and RCC-41-PDX-2/CD133+/EpCAMbright). In addition, transcriptomic analysis showed that RCC-41-PDX-2/CD133- over-expressed the pluripotency gene ERBB4, while RCC-41-PDX-2/CD133+ over-expressed several tumor suppressor genes. These three CSC subsets displayed ALDH activity, formed serial spheroids and developed serial tumors in SCID mice, although RCC-41-PDX-1/CD132+ and RCC-41-PDX-2/CD133+ displayed less efficiently the above CSC properties. RCC-41-PDX-1/CD132+ tumors showed vessels of human origin with CSC displaying peri-vascular distribution. By contrast, RCC-41-PDX-2 originated tumors exhibiting only vessels of mouse origin without CSC peri-vascular distribution.Altogether, our results indicate that PDX murine microenvironment promotes a continuous redesign of CSC phenotype, unmasking CSC subsets potentially present in a single RCC or generating ex novo different CSC-like subsets.


Assuntos
Carcinoma de Células Renais/patologia , Xenoenxertos , Neoplasias Renais/patologia , Células-Tronco Neoplásicas/patologia , Animais , Técnicas de Cultura de Células/métodos , Separação Celular/métodos , Citometria de Fluxo/métodos , Humanos , Camundongos , Camundongos SCID , Células Tumorais Cultivadas
10.
Neoplasia ; 17(6): 509-17, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26152359

RESUMO

Intrarenal interleukin-15 (IL-15) participates to renal pathophysiology, but the role of its different membrane-bound isoforms remains to be elucidated. In this study, we reassess the biology of membrane-bound IL-15 (mb-IL-15) isoforms by comparing primary cultures of human renal proximal tubular epithelial cells (RPTEC) to peritumoral (ptumTEC), tumoral (RCC), and cancer stem cells (CSC/CD105(+)). RPTEC express a 14 to 16 kDa mb-IL-15, whose existence has been assumed but never formally demonstrated and likely represents the isoform anchored at the cell membrane through the IL-15 receptor α (IL-15Rα) chain, because it is sensitive to acidic treatment and is not competent to deliver a reverse signal. By contrast, ptumTEC, RCC, and CSC express a novel N-hyperglycosylated, short-lived transmembrane mb-IL-15 (tmb-IL-15) isoform around 27 kDa, resistant to acidic shock, delivering a reverse signal in response to its soluble receptor (sIL-15Rα). This reverse signal triggers the down-regulation of the tumor suppressor gene E-cadherin in ptumTEC and RCC but not in CSC/CD105(+), where it promotes survival. Indeed, through the AKT pathway, tmb-IL-15 protects CSC/CD105(+) from non-programmed cell death induced by serum starvation. Finally, both mb-IL-15 and tmb-IL-15 are sensitive to metalloproteases, and the cleaved tmb-IL-15 (25 kDa) displays a powerful anti-apoptotic effect on human hematopoietic cells. Overall, our data indicate that both mb-IL-15 and tmb-IL-15 isoforms play a complex role in renal pathophysiology downregulating E-cadherin and favoring cell survival. Moreover, "apparently normal" ptumTEC cells, sharing different properties with RCC, could contribute to organize an enlarged peritumoral "preneoplastic" environment committed to favor tumor progression.


Assuntos
Carcinoma de Células Renais/patologia , Membrana Celular/metabolismo , Interleucina-15/metabolismo , Neoplasias Renais/patologia , Túbulos Renais Proximais/patologia , Células-Tronco Neoplásicas/patologia , Apoptose , Western Blotting , Carcinoma de Células Renais/metabolismo , Proliferação de Células , Células Cultivadas , Transição Epitelial-Mesenquimal , Citometria de Fluxo , Humanos , Neoplasias Renais/metabolismo , Túbulos Renais Proximais/metabolismo , Células-Tronco Neoplásicas/metabolismo , Isoformas de Proteínas , Microambiente Tumoral
11.
Toxicon ; 84: 1-6, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24680766

RESUMO

It is expected that humans are exposed to combined mycotoxins, which occur simultaneously in the food items, than to individual compounds and that can increase their potential toxicity. Considering this coincident production, deoxynivalenol (DON) and zearalenone (ZEN) as they are produced by several Fusarium species, can interfere at a cellular level. Therefore, these two toxins were chosen to study their interactive effects on human colon carcinoma cells (HCT116), using the endpoints including cell viability, cell cycle analysis, mitochondrial transmembrane potential (ΔΨm) determination and permeability transition pore (PTP) opening. Our results showed that DON and ZEN caused a marked decrease of cell viability in a dose-dependent manner, mediated by an activation of the mitochondrial apoptotic process; characterized by PTP opening and the loss of ΔΨm. Nevertheless, combined DON and ZEN reduced all the toxicities observed with the mycotoxins separately. Therefore, the combination of the two mycotoxins appears as a sub-additive response.


Assuntos
Micotoxinas/toxicidade , Tricotecenos/toxicidade , Zearalenona/toxicidade , Apoptose/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células HCT116 , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Proteínas de Transporte da Membrana Mitocondrial/efeitos dos fármacos , Poro de Transição de Permeabilidade Mitocondrial
12.
Biochem Pharmacol ; 83(9): 1172-82, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22285227

RESUMO

A major clinical problem regarding antitumoral treatment with DNA cross-linking agents such as cisplatin (Cisp), mechlorethamine (HN2) or its derivative melphalan (MLP) is intrinsic or acquired resistance to therapy, which frequently results from a resistance to apoptosis induction. In this study, aimed to identify novel sensitizing targets to DNA cross-linker-induced cell death, we demonstrated that MLP, Cisp and HN2 induce mitochondrial permeability transition pore (PTP)-mediated apoptosis in cervical and colon carcinoma cells. This apoptotic pathway is characterized by dissipation of the mitochondrial membrane potential, production of ROS, mitochondrial translocation of Bax, release of apoptogenic factors, caspase activation and nuclear alterations. The opening of PTP and subsequent apoptosis was reduced in Bax deficient cells and in cells with elevated Bcl-2 level, but not in cells invalidated for Bak. We further showed that, among the pro-apoptotic PTP regulators tested (VDAC1, creatine kinase, ANT1 and ANT3), exogenous overexpression of VDAC1 was the most effective in enhancing Cisp- and MLP-induced apoptosis. In addition, pharmacologically induced up-regulation of VDAC1 by the chemotherapeutic agent arsenic trioxide (As(2)O(3)) greatly sensitized HeLa cells to Cisp and MLP treatment. These data indicate that increased expression of VDAC1 appears as a promising strategy to improve DNA cross-linker-induced chemotherapy.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Reagentes de Ligações Cruzadas/farmacologia , Canal de Ânion 1 Dependente de Voltagem/metabolismo , Linhagem Celular Tumoral , Cisplatino/farmacologia , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Reagentes de Ligações Cruzadas/química , DNA/química , Feminino , Células HeLa , Humanos , Mecloretamina/farmacologia , Melfalan/farmacologia , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Neoplasias do Colo do Útero/tratamento farmacológico , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/patologia , Canal de Ânion 1 Dependente de Voltagem/genética , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Proteína X Associada a bcl-2/metabolismo
13.
Food Chem Toxicol ; 50(5): 1680-9, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22281158

RESUMO

Deoxynivalenol (DON) is a widespread trichothecene mycotoxin which contaminates cereal crops and harmfully affects the gastrointestinal tract. Since it is well known that mitochondria play a central role in apoptosis triggered by many stimuli, an effort was made to examine whether DON-induced cytotoxicity occurs through mitochondria-mediated apoptotic pathway. The intestinal system being one of the primary targets of mycotoxins, the human colon carcinoma cell line HCT116 was used in this study. Using flow cytometric analyses and immunofluorescence, we showed that DON at 100 µM induced a mitochondria-dependent apoptotic pathway associated with opening of the mitochondrial permeability transition pore (PTP), loss of the mitochondrial transmembrane potential (ΔΨm), downstream generation of O2·â» and cytochrome c release. The DON-induced apoptosis was accompanied by an activation of caspase 9 and 3, as demonstrated by Western blot and caspase activity assay. In addition, by taking advantage of HCT116 cells invalidated for Bax, we showed that this pro-apoptotic protein favored mitochondrial alterations induced by the mycotoxin. Besides, incubation of purified mitochondria with DON indicated that this mycotoxin does not directly target mitochondria to induce PTP-dependent permeabilization of mitochondrial membranes. Altogether, our results indicate that mitochondria-related caspase-dependent apoptotic pathway is involved in this in vitro model of DON induced-cytotoxicity.


Assuntos
Apoptose/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Tricotecenos/toxicidade , Caspases/metabolismo , Linhagem Celular Tumoral , Citocromos c/metabolismo , Ativação Enzimática , Humanos , Metaloproteinases da Matriz/metabolismo , Potenciais da Membrana/efeitos dos fármacos
14.
Toxicol In Vitro ; 26(6): 915-23, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22542754

RESUMO

Mycotoxins are unavoidable contaminants of most foods and feeds, and some are known to be detrimental to human health. It is thus worthwhile to understand how cells of the intestinal system, one of the primary targets of these toxins, respond to their toxic effects. In this study, human colon carcinoma cells were used to elucidate the cell death mode and the pathways triggered by Alternariol (AOH), the most important mycotoxin produced by Alternaria species, which are the most common mycoflora infecting small grain cereals worldwide. Treatment of cells with AOH resulted in a loss of cell viability by inducing apoptosis. AOH-induced apoptosis was mediated through a mitochondria-dependent pathway, characterized by a p53 activation, an opening of the mitochondrial permeability transition pore (PTP), a loss of mitochondrial transmembrane potential (ΔΨm), a downstream generation of O(2)(*-) and caspase 9 and 3 activation. Besides, deficiency of the pro-apoptotic protein Bax partially protected cells against AOH-induced mitochondrial alterations. In addition, experiments performed on purified mitochondria indicated that AOH does not directly target this organelle to induce cell death. Our results demonstrate for the first time that AOH-induced cytotoxicity is mediated by activation of the mitochondrial pathway of apoptosis in human colon carcinoma cells.


Assuntos
Alternaria , Lactonas/toxicidade , Micotoxinas/toxicidade , Caspase 3/metabolismo , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Fragmentação do DNA , Células HCT116 , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Proteína X Associada a bcl-2/metabolismo
15.
Toxicology ; 290(2-3): 230-40, 2011 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-22001388

RESUMO

Alternariol monomethyl ether (AME) is a major mycotoxin produced by fungi of the genus Alternaria and a common contaminant of food products such as fruits and cereals worldwide. AME can cause serious health problems for animals as well as for humans. In this study, human colon carcinoma cells (HCT116) were used to explore the mechanisms of cell death induced by AME. Exposure of HCT116 cells to AME resulted in significant cytotoxicity manifested by a loss in cell viability mainly mediated by activation of apoptotic process. AME activated the mitochondrial apoptotic pathway evidenced by the opening of the mitochondrial permeability transition pore (PTP), loss of the mitochondrial transmembrane potential (ΔΨm) downstream generation of O(2)(-), cytochrome c release and caspase 9 and 3 activation. Experiments conducted on isolated organelles indicated that AME does not directly target mitochondria to induce PTP-dependent permeabilization of mitochondrial membranes. Moreover, no difference was observed in Bax-KO cells in comparison to parental cells, suggesting that the pro-apoptotic protein Bax is not involved in AME-induced mitochondrial apoptosis. Our findings demonstrate for the first time that AME induces cell death in human colon carcinoma cells by activating the mitochondrial pathway of apoptosis.


Assuntos
Apoptose/efeitos dos fármacos , Neoplasias Colorretais/tratamento farmacológico , Lactonas/farmacologia , Mitocôndrias/efeitos dos fármacos , Micotoxinas/farmacologia , Linhagem Celular Tumoral , Neoplasias Colorretais/patologia , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/metabolismo , Membranas Mitocondriais/efeitos dos fármacos , Membranas Mitocondriais/metabolismo , Permeabilidade , Proteína X Associada a bcl-2/metabolismo
16.
Int J Biochem Cell Biol ; 42(5): 623-9, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20060930

RESUMO

The adenine nucleotide translocator (ANT) is a mitochondrial bi-functional protein, which catalyzes the exchange of ADP and ATP between cytosol and mitochondria and participates in many models of mitochondrial apoptosis. The human adenine nucleotide translocator sub-family is composed of four isoforms, namely ANT1-4, encoded by four nuclear genes, whose expression is highly regulated. Previous studies have revealed that ANT1 and 3 induce mitochondrial apoptosis, whereas ANT2 is anti-apoptotic. However, the role of the recently identified isoform ANT4 in the apoptotic pathway has not yet been elucidated. Here, we investigated the effects of stable heterologous expression of the ANT4 on proliferation, mitochondrial respiration and cell death in human cancer cells, using ANT3 as a control of pro-apoptotic isoform. As expected, ANT3 enhanced mitochondria-mediated apoptosis in response to lonidamine, a mitochondriotoxic chemotherapeutic drug, and staurosporine, a protein kinase inhibitor. Our results also indicate that the pro-apoptotic effect of ANT3 was accompanied by decreased rate of cell proliferation, alteration in the mitochondrial network topology, and decreased reactive oxygen species production. Of note, we demonstrate for the first time that ANT4 enhanced cell growth without impacting mitochondrial network or respiration. Moreover, ANT4 differentially regulated the intracellular levels of hydrogen peroxide without affecting superoxide anion levels. Finally, stable ANT4 overexpression protected cancer cells from lonidamine and staurosporine apoptosis in a manner independent of Bcl-2 expression. These data highlight a hitherto undefined cytoprotective activity of ANT4, and provide a novel dichotomy in the human ANT isoform sub-family with ANT1 and 3 isoforms functioning as pro-apoptotic while ANT2 and 4 isoforms render cells resistant to death inducing stimuli.


Assuntos
Apoptose , Mitocôndrias/fisiologia , Translocases Mitocondriais de ADP e ATP/fisiologia , Translocador 3 do Nucleotídeo Adenina/biossíntese , Translocador 3 do Nucleotídeo Adenina/genética , Translocador 3 do Nucleotídeo Adenina/fisiologia , Antineoplásicos/farmacologia , Caspase 9/metabolismo , Proliferação de Células , Forma Celular , Citoproteção , Células HeLa , Humanos , Peróxido de Hidrogênio/análise , Indazóis/farmacologia , Isoenzimas/biossíntese , Isoenzimas/genética , Isoenzimas/fisiologia , Translocases Mitocondriais de ADP e ATP/biossíntese , Translocases Mitocondriais de ADP e ATP/sangue , Translocases Mitocondriais de ADP e ATP/genética , Fosforilação Oxidativa , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Estaurosporina/farmacologia , Superóxidos/análise
17.
Front Biosci (Landmark Ed) ; 14(9): 3465-82, 2009 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-19273287

RESUMO

The ndoplasmic reticulum (ER) function is critical for multiple cellular activities. Hence, impairment of the physiological function of the ER, such as accumulation of unfolded proteins or disturbance of lumenal calcium homeostasis, leads to an evolutionarily conserved adaptive response known as the ER stress response. Activation of this self-protective pathway gives the cell a chance to restore normal ER function. In the case of prolonged or severe stress conditions, or if the ER dysfunctions cannot be compensated, apoptosis is ultimately activated to eliminate stressed cells. Although the molecular mechanisms involved in ER stress-mediated apoptosis are poorly understood, it is known that ER and mitochondria can cooperate to induce cell death. In this review, we discuss the commitment and development of the lethal crosstalk between ER and mitochondria and focus on the role of the mitochondrial permeability transition pore complex in these processes.


Assuntos
Permeabilidade da Membrana Celular , Organelas/fisiologia , Apoptose , Retículo Endoplasmático/fisiologia , Mitocôndrias/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA