RESUMO
Leukotriene A4 hydrolase (LTA4H), a bifunctional zinc metallo-enzyme, is reportedly overexpressed in several human cancers. Our group has focused on LTA4H as a potential target for cancer prevention and/or therapy. In the present study, we report that LTA4H is a key regulator of cell cycle at the G0/G1 phase acting by negatively regulating p27 expression in skin cancer. We found that LTA4H is overexpressed in human skin cancer tissue. Knocking out LTA4H significantly reduced skin cancer development in the 7,12-dimethylbenz(a)anthracene (DMBA)-initiated/12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted two-stage skin cancer mouse model. LTA4H depletion dramatically decreased anchorage-dependent and -independent skin cancer cell growth by inducing cell cycle arrest at the G0/G1 phase. Moreover, our findings showed that depletion of LTA4H enhanced p27 protein stability, which was associated with decreased phosphorylation of CDK2 at Thr160 and inhibition of the CDK2/cyclin E complex, resulting in down-regulated p27 ubiquitination. These findings indicate that LTA4H is critical for skin carcinogenesis and is an important mediator of cell cycle and the data begin to clarify the mechanisms of LTA4H's role in cancer development.
Assuntos
Carcinogênese/genética , Ciclo Celular/genética , Epóxido Hidrolases/genética , Neoplasias Cutâneas/genética , 9,10-Dimetil-1,2-benzantraceno/toxicidade , Animais , Quinase 2 Dependente de Ciclina/biossíntese , Quinase 2 Dependente de Ciclina/genética , Epóxido Hidrolases/biossíntese , Fase G1 , Humanos , Camundongos , Fosforilação , Antígeno Nuclear de Célula em Proliferação/biossíntese , Piridinas/toxicidade , Neoplasias Cutâneas/induzido quimicamente , Neoplasias Cutâneas/patologiaRESUMO
Non-small cell lung cancer (NSCLC) is the most lethal cancer, causing more than 150,000 deaths in the United States in 2013. The receptor tyrosine kinase inhibitors such as gefitinib are not perfect clinical therapeutic agents for NSCLC treatment due to primary or acquired tyrosine kinase inhibitor resistance. Herein, 3,6,2',4',5'-pentahydroxyflavone (36245-PHF) was identified as a multiple kinase inhibitor for NSCLC treatment based on the computational screening of a natural products database. 36245-PHF was shown to inhibit PI3K and Aurora A and B kinases and overcome gefitinib-resistant NSCLC growth. Our data clearly showed that 36245-PHF markedly inhibited anchorage-independent growth of gefitinib-resistant NSCLC cell lines and exerted a substantial chemotherapeutic effect following oral administration in a gefitinib-resistant NSCLC xenograft model. The evidence from three different subsequent methodological approaches, in vitro, ex vivo, and in vivo, all confirmed that 36245-PHF as a multiple protein kinase inhibitor. Overall, we identified 36245-PHF as a multiple protein kinase inhibitor and as a novel therapeutic agent to overcome gefitinib-resistant NSCLC growth, which could provide a new option for clinical NSCLC oral treatment.
Assuntos
Antineoplásicos/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Flavonoides/farmacologia , Regulação Neoplásica da Expressão Gênica , Neoplasias Pulmonares/tratamento farmacológico , Inibidores de Proteínas Quinases/farmacologia , Quinazolinas/farmacologia , Animais , Aurora Quinase A/antagonistas & inibidores , Aurora Quinase A/genética , Aurora Quinase A/metabolismo , Aurora Quinase B/antagonistas & inibidores , Aurora Quinase B/genética , Aurora Quinase B/metabolismo , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Adesão Celular , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Gefitinibe , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Nus , Transplante de Neoplasias , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Transdução de Sinais , Carga Tumoral/efeitos dos fármacosRESUMO
Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide. Despite progress in developing chemotherapeutics for the treatment of NSCLC, primary and secondary resistance limits therapeutic success. NSCLC cells exhibit multiple mutations in the epidermal growth factor receptor (EGFR), which cause aberrant activation of diverse cell signaling pathways. Therefore, suppression of the inappropriate amplification of EGFR downstream signaling cascades is considered to be a rational therapeutic and preventive strategy for the management of NSCLC. Our initial molecular target-oriented virtual screening revealed that the ginger components, including [6]-shogaol, [6]-paradol and [6]-gingerol, seem to be potential candidates for the prevention and treatment of NSCLC. Among the compounds, [6]-shogaol showed the greatest inhibitory effects on the NSCLC cell proliferation and anchorage-independent growth. [6]-Shogaol induced cell cycle arrest (G1 or G2/M) and apoptosis. Furthermore, [6]-shogaol inhibited Akt kinase activity, a downstream mediator of EGFR signaling, by binding with an allosteric site of Akt. In NCI-H1650 lung cancer cells, [6]-shogaol reduced the constitutive phosphorylation of signal transducer and activator of transcription-3 (STAT3) and decreased the expression of cyclin D1/3, which are target proteins in the Akt signaling pathway. The induction of apoptosis in NCI-H1650 cells by [6]-shogaol corresponded with the cleavage of caspase-3 and caspase-7. Moreover, intraperitoneal administration of [6]-shogaol inhibited the growth of NCI-H1650 cells as tumor xenografts in nude mice. [6]-Shogaol suppressed the expression of Ki-67, cyclin D1 and phosphorylated Akt and STAT3 and increased terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positivity in xenograft tumors. The current study clearly indicates that [6]-shogaol can be exploited for the prevention and/or treatment of NSCLC.
Assuntos
Apoptose/efeitos dos fármacos , Carcinoma Pulmonar de Células não Pequenas/patologia , Catecóis/farmacologia , Divisão Celular/efeitos dos fármacos , Neoplasias Pulmonares/patologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Carcinoma Pulmonar de Células não Pequenas/enzimologia , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Humanos , Neoplasias Pulmonares/enzimologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de SinaisRESUMO
Chrysin (5,7-dihydroxyflavone), a natural flavonoid widely distributed in plants, reportedly has chemopreventive properties against various cancers. However, the anticancer activity of chrysin observed in in vivo studies has been disappointing. Here, we report that a chrysin derivative, referred to as compound 69407, more strongly inhibited EGF-induced neoplastic transformation of JB6 P(+) cells compared with chrysin. It attenuated cell cycle progression of EGF-stimulated cells at the G1 phase and inhibited the G1/S transition. It caused loss of retinoblastoma phosphorylation at both Ser-795 and Ser-807/811, the preferred sites phosphorylated by Cdk4/6 and Cdk2, respectively. It also suppressed anchorage-dependent and -independent growth of A431 human epidermoid carcinoma cells. Compound 69407 reduced tumor growth in the A431 mouse xenograft model and retinoblastoma phosphorylation at Ser-795 and Ser-807/811. Immunoprecipitation kinase assay results showed that compound 69407 attenuated endogenous Cdk4 and Cdk2 kinase activities in EGF-stimulated JB6 P(+) cells. Pulldown and in vitro kinase assay results indicated that compound 69407 directly binds with Cdk2 and Cdk4 in an ATP-independent manner and inhibited their kinase activities. A binding model between compound 69407 and a crystal structure of Cdk2 predicted that compound 69407 was located inside the Cdk2 allosteric binding site. The binding was further verified by a point mutation binding assay. Overall results indicated that compound 69407 is an ATP-noncompetitive cyclin-dependent kinase inhibitor with anti-tumor effects, which acts by binding inside the Cdk2 allosteric pocket. This study provides new insights for creating a general pharmacophore model to design and develop novel ATP-noncompetitive agents with chemopreventive or chemotherapeutic potency.
Assuntos
Carcinoma de Células Escamosas/tratamento farmacológico , Quinases Ciclina-Dependentes/antagonistas & inibidores , Flavonoides/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Neoplasias Cutâneas/tratamento farmacológico , Regulação Alostérica/efeitos dos fármacos , Animais , Sítios de Ligação , Carcinoma de Células Escamosas/enzimologia , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Cristalografia por Raios X , Quinases Ciclina-Dependentes/genética , Quinases Ciclina-Dependentes/metabolismo , Fator de Crescimento Epidérmico/genética , Fator de Crescimento Epidérmico/metabolismo , Flavonoides/química , Fase G1/efeitos dos fármacos , Fase G1/genética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Modelos Moleculares , Transplante de Neoplasias , Inibidores de Proteínas Quinases/química , Proteína do Retinoblastoma/genética , Proteína do Retinoblastoma/metabolismo , Fase S/efeitos dos fármacos , Fase S/genética , Neoplasias Cutâneas/enzimologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologiaRESUMO
Ceftriaxone, an FDA-approved third-generation cephalosporin antibiotic, has antimicrobial activity against both gram-positive and gram-negative organisms. Generally, ceftriaxone is used for a variety of infections such as community-acquired pneumonia, meningitis and gonorrhea. Its primary molecular targets are the penicillin-binding proteins. However, other activities of ceftriaxone remain unknown. Herein, we report for the first time that ceftriaxone has antitumor activity in vitro and in vivo. Kinase profiling results predicted that Aurora B might be a potential 'off' target of ceftriaxone. Pull-down assay data confirmed that ceftriaxone could bind with Aurora B in vitro and in A549 cells. Furthermore, ceftriaxone (500 µM) suppressed anchorage-independent cell growth by targeting Aurora B in A549, H520 and H1650 lung cancer cells. Importantly, in vivo xenograft animal model results showed that ceftriaxone effectively suppressed A549 and H520 lung tumor growth by inhibiting Aurora B. These data suggest the anticancer efficacy of ceftriaxone for the treatment of lung cancers through its inhibition of Aurora B.
Assuntos
Antibacterianos/farmacologia , Ceftriaxona/farmacologia , Neoplasias Pulmonares/tratamento farmacológico , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Animais , Aurora Quinase B , Aurora Quinases , Linhagem Celular Tumoral , Fator de Crescimento Epidérmico/farmacologia , Humanos , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/patologia , CamundongosRESUMO
3,3'-Diindolymethane (DIM) is a dimeric condensation product of indole-3-carbinol (I3C) that is found in broccoli and cabbage. Although DIM has been reported to exhibit anticancer properties against multiple tumor types, the direct target proteins of DIM have not been fully investigated. In the present study, we report that DIM is a novel COX1/2 and ERK1/2 inhibitor that suppresses growth of colon cancer in vitro and in vivo. To identify possible molecular targets of DIM, 11 potential candidate proteins were validated by an in vitro kinase or enzyme assay. We found that DIM directly inhibits COX1/2 and ERK1/2 protein activities in vitro. Additionally, the PGE2 production (COX-mediated metabolite) and phosphorylated RSK expression (ERK1/2 direct downstream kinase) were strongly suppressed by DIM in colon cancer cells. The inhibition of cell growth by DIM is dependent on the expression of COX1/2 or ERK1/2 proteins. Notably, oral administration of DIM suppressed patient-derived xenograft colon tumor growth in an in vivo mouse model. Overall these results suggest that DIM is a potent and dual COX1/2 and ERK1/2 inhibitor that might be used for chemotherapy against colon cancer.
Assuntos
Anticarcinógenos/farmacologia , Inibidores de Ciclo-Oxigenase/farmacologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Indóis/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Neoplasias do Colo/tratamento farmacológico , Ciclo-Oxigenase 2/metabolismo , Humanos , Camundongos , Transdução de Sinais/efeitos dos fármacos , Células Tumorais CultivadasRESUMO
Quercetin exhibits a potent anticarcinogenic activity. However, ingested quercetin circulates as the glucuronide/sulfate conjugates, which are less active compared to the aglycone in healthy individuals. This study aimed to develop further understandings of the cancer-preventing mechanism with dietary quercetin. According to a two-stage hepatocarcinogenesis model with N-diethylnitrosamine (DEN) and phenobarbital (PB), preneoplasms were induced specifically in the liver of Fisher 344 rats. In the liver, glutathione S-transferase placental form (GST-P) positive foci were produced 14 weeks later. beta-Glucuronidase activity increased significantly in the liver by 1.2-fold in the DEN/PB group compared to the activity in a saline group. In the kidney, thymus, lung, heart, and plasma, the activities were similar between both groups. When quercetin was dosed intragastrically 15 min before sacrifice, the aglycone level of quercetin in liver was significantly 1.9-fold higher in the DEN/PB group than in the saline group. On the other hand, quercetin was dosed to rats 3 times a week for 14 weeks. The treatment kept the aglycone level of quercetin at a significantly higher level and tended to suppress the formation of GST-P positive foci. The increase in beta-glucuronidase activity with carcinogenesis induction became insignificant following the frequent doses of quercetin. It was considered that quercetin aglycone played a preventative role and, thus, the conjugates were converted to the active aglycone by beta-glucuronidase that was induced by the generation of preneoplasms.
Assuntos
Glucuronídeos/metabolismo , Neoplasias Hepáticas Experimentais/induzido quimicamente , Neoplasias Hepáticas Experimentais/prevenção & controle , Quercetina/administração & dosagem , Quercetina/metabolismo , Animais , Glucuronidase/metabolismo , Glucuronosiltransferase/metabolismo , Fígado/enzimologia , Neoplasias Hepáticas Experimentais/enzimologia , Masculino , Ratos , Ratos Endogâmicos F344RESUMO
Malignant melanoma is an aggressive tumor of the skin and still lacks effective preventive and therapeutic treatments. In melanoma, both the BRAF/MEK/ERK and PI3-K/AKT signaling pathways are constitutively activated through multiple mechanisms, which result in cell-cycle progression and prevention of apoptosis. Therefore, the development of novel strategies for targeting BRAF and PI3K are of utmost importance. In this study, we found that Ashitaba (Angelica keiskei) chalcones, 4-hydroxyderricin (4HD) and xanthoangelol (XAG), suppressed melanoma development by directly targeting both BRAFV600E and PI3K, which blocked the activation of downstream signaling. This led to the induction of G1 phase cell-cycle arrest and apoptosis in melanoma cells. Importantly, 4HD or XAG dramatically attenuated tumor incidence and volume in the BRAF-activated Pten-deficient melanoma mouse model. Our findings suggest that 4HD and XAG are promising chemopreventive or potential therapeutic agents against melanomagenesis that act by targeting both BRAF and PI3K, providing hope for rapid clinical translation. Cancer Prev Res; 11(10); 607-20. ©2018 AACR.
Assuntos
Carcinogênese/efeitos dos fármacos , Chalcona/análogos & derivados , Melanoma Experimental/prevenção & controle , Extratos Vegetais/farmacologia , Neoplasias Cutâneas/prevenção & controle , Angelica/química , Animais , Carcinogênese/patologia , Linhagem Celular Tumoral , Chalcona/farmacologia , Chalcona/uso terapêutico , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Melanoma Experimental/induzido quimicamente , Melanoma Experimental/genética , Melanoma Experimental/patologia , Camundongos , Camundongos Knockout , Mutação , PTEN Fosfo-Hidrolase/genética , Fosfatidilinositol 3-Quinases/metabolismo , Extratos Vegetais/uso terapêutico , Proteínas Proto-Oncogênicas B-raf/genética , Transdução de Sinais/efeitos dos fármacos , Neoplasias Cutâneas/induzido quimicamente , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Resultado do TratamentoRESUMO
Bioavailability of glabridin was elucidated to show that this compound is one of the active components in the traditional medicine licorice. Using a model of intestinal absorption, Caco-2 cell monolayer, incorporation of glabridin was examined. Glabridin was easily incorporated into the cells and released to the basolateral side at a permeability coefficient of 1.70+/-0.16 cm/s x 10(5). The released glabridin was the aglycone form and not a conjugated form. Then, 10 mg (30 micromol)/kg body weight of standard chemical glabridin and licorice flavonoid oil (LFO) containing 10 mg/kg body weight of glabridin were administered orally to rats, and the blood concentrations of glabridin was determined. Glabridin showed a maximum concentration 1 h after the dose, of 87 nmol/L for standard glabridin and 145 nmol/L for LFO glabridin, and decreased gradually over 24 h after the dose. The level of incorporation into the liver was about 0.43% of the dosed amount 2 h after the dose. These detected glabridins were in the aglycone form and not conjugated forms. The bioavailability was calculated to be AUC(inf) of 0.825 and 1.30 microM.h and elimination T(1/2 )of 8.2 and 8.5 h for standard glabridin and LFO, respectively. Adipocytokine levels were determined in the rats. The secreted amount of monocyte chemoattractant protein-1 was significantly lower in the glabridin group compared to control vehicle group. Thus, dietary glabridin was at least partly incorporated into the body in an unchanged form, though most dietary flavonoids are converted to non-active conjugate forms during intestinal absorption.
Assuntos
Mucosa Intestinal/metabolismo , Fenóis/sangue , Fenóis/farmacocinética , Adiponectina/sangue , Adiponectina/metabolismo , Animais , Disponibilidade Biológica , Células CACO-2 , Sobrevivência Celular/fisiologia , Quimiocina CCL2/sangue , Glycyrrhiza/química , Humanos , Insulina/sangue , Insulina/metabolismo , Secreção de Insulina , Absorção Intestinal , Isoflavonas , Leptina/sangue , Leptina/metabolismo , Fígado/metabolismo , Masculino , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Fator de Necrose Tumoral alfa/sangue , Fator de Necrose Tumoral alfa/metabolismoRESUMO
TRAF1 is a member of the TRAF protein family, which regulates the canonical and noncanonical NF-κB signaling cascades. Although aberrant TRAF1 expression in tumors has been reported, the role of TRAF1 remains elusive. Here, we report that TRAF1 is required for solar UV-induced skin carcinogenesis. Immunohistochemical analysis showed that TRAF1 expression is up-regulated in human actinic keratosis and squamous cell carcinoma. In vivo studies indicated that TRAF1 expression levels in mouse skin are induced by short-term solar UV irradiation, and a long-term skin carcinogenesis study showed that deletion of TRAF1 in mice results in a significant inhibition of skin tumor formation. Moreover, we show that TRAF1 is required for solar UV-induced extracellular signal-regulated kinase-5 (ERK5) phosphorylation and the expression of AP-1 family members (c-Fos/c-Jun). Mechanistic studies showed that TRAF1 expression enhances the ubiquitination of ERK5 on lysine 184, which is necessary for its kinase activity and AP-1 activation. Overall, our results suggest that TRAF1 mediates ERK5 activity by regulating the upstream effectors of ERK5 and also by modulating its ubiquitination status. Targeting TRAF1 function might lead to strategies for preventing and treating skin cancer.
Assuntos
Carcinogênese/efeitos da radiação , Regulação da Expressão Gênica , Queratinócitos/efeitos da radiação , Fator 1 Associado a Receptor de TNF/genética , Raios Ultravioleta/efeitos adversos , 9,10-Dimetil-1,2-benzantraceno/farmacologia , Análise de Variância , Animais , Carcinogênese/efeitos dos fármacos , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Modelos Animais de Doenças , Células Epidérmicas , Epiderme/patologia , Cromatografia Gasosa-Espectrometria de Massas/métodos , Queratinócitos/citologia , Queratinócitos/patologia , Ceratose Actínica/etiologia , Ceratose Actínica/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Proteína Quinase 7 Ativada por Mitógeno/metabolismo , Proteína Quinase 7 Ativada por Mitógeno/efeitos da radiação , Distribuição Aleatória , Transdução de Sinais , Neoplasias Cutâneas/etiologia , Neoplasias Cutâneas/fisiopatologia , Regulação para CimaRESUMO
Esophageal cancer is one of the least studied and deadliest cancers worldwide with a poor prognosis due to limited options for treatment. Chemotherapy agents such as the microtubule-targeting compounds are the mainstay of palliation for advanced esophageal cancer treatment. However, the toxicity and side effects of tubulin-binding agents (TBAs) have promoted the development of novel, more potent but less toxic TBAs. Herein, we identified 2-[4-(3,4-dimethoxyphenyl)-3-methyl-1H-pyrazol-5-yl]-5-[(2-methylprop-2-en-1-yl)oxy] phenol (PPMP) as a novel TBA for esophageal cancer treatment. PPMP markedly inhibited tubulin polymerization, and decreased viability and anchorage-independent growth of esophageal cancer cell lines, effects that were accompanied by G2/M arrest and apoptosis. Importantly, we produced patient-derived esophageal cancer xenografts to evaluate the therapeutic effect of PPMP in a setting that best mimics the clinical context in patients with esophageal cancer. Overall, we identified PPMP as a novel microtubule-destabilizing compound and as a new therapeutic agent against esophageal carcinoma.
Assuntos
Neoplasias Esofágicas/tratamento farmacológico , Meperidina/análogos & derivados , Moduladores de Tubulina/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias Esofágicas/metabolismo , Neoplasias Esofágicas/patologia , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Humanos , Pontos de Checagem da Fase M do Ciclo Celular/efeitos dos fármacos , Masculino , Meperidina/farmacologia , Camundongos , Pessoa de Meia-Idade , Modelos Moleculares , Tubulina (Proteína)/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Ornithine decarboxylase (ODC) is a rate-limiting enzyme in the first step of polyamine biosynthesis that is associated with cell growth and tumor formation. Existing catalytic inhibitors of ODC have lacked efficacy in clinical testing or displayed unacceptable toxicity. In this study, we report the identification of an effective and nontoxic allosteric inhibitor of ODC. Using computer docking simulation and an in vitro ODC enzyme assay, we identified herbacetin, a natural compound found in flax and other plants, as a novel ODC inhibitor. Mechanistic investigations defined aspartate 44 in ODC as critical for binding. Herbacetin exhibited potent anticancer activity in colon cancer cell lines expressing high levels of ODC. Intraperitoneal or oral administration of herbacetin effectively suppressed HCT116 xenograft tumor growth and also reduced the number and size of polyps in a mouse model of APC-driven colon cancer (ApcMin/+). Unlike the well-established ODC inhibitor DFMO, herbacetin treatment was not associated with hearing loss. Taken together, our findings defined the natural product herbacetin as an allosteric inhibitor of ODC with chemopreventive and antitumor activity in preclinical models of colon cancer, prompting its further investigation in clinical trials.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Flavonoides/farmacologia , Inibidores da Ornitina Descarboxilase/farmacologia , Regulação Alostérica , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Anticarcinógenos/farmacologia , Eflornitina/farmacologia , Feminino , Flavonoides/toxicidade , Células HCT116 , Perda Auditiva/induzido quimicamente , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ornitina Descarboxilase/química , Ornitina Descarboxilase/metabolismoRESUMO
BACKGROUND: Colorectal cancer (CRC) represents the third leading cause of cancer-related death in the United States. Lack of reliable biomarkers remains a critical issue for early detection of CRC. In this study, we investigated the potential predictive values of circulating prostaglandin (PG) biosynthesis in CRC risk. METHODS: Profiles of circulating PG biosynthesis and platelet counts were determined in healthy subjects (n = 16), familial adenomatous polyposis (FAP) patients who were classified as regular aspirin users (n = 14) or nonusers (n = 24), and CRC patients with (n = 18) or without FAP history (n = 20). Immunohistochemistry staining was performed on biopsy samples. RESULTS: Analysis of circulating PG biosynthesis unexpectedly revealed that CRC progression is accompanied by a pronounced elevation of circulating thromboxane A2 (TXA2) levels. When a circulating TXA2 level of 1000 pg/mL was selected as a practical cutoff point, 95% of CRC patients were successfully identified. Further study suggested that the TXA2 pathway is constitutively activated during colorectal tumorigenesis and required for anchorage-independent growth of colon cancer cells. CONCLUSIONS: This study established the importance of the TXA2 pathway in CRC pathophysiology, and laid the groundwork for introducing a TXA2-targeting strategy to CRC prevention, early detection and management.
RESUMO
BACKGROUND: Aspirin intake reduces the risk of colorectal cancer (CRC), but the molecular underpinnings remain elusive. Epidermal growth factor receptor (EGFR), which is overexpressed in about 80% of CRC cases, is implicated in the etiology of CRC. Here, we investigated whether aspirin can prevent CRC by normalizing EGFR expression. METHODS: Immunohistochemistry staining was performed on paraffin-embedded tissue sections from normal colon mucosa, adenomatous polyps from FAP patients who were classified as regular aspirin users or nonusers. The interplay between cyclooxygenase-2 (COX-2) and EGFR was studied in primary intestinal epithelial cells isolated from ApcMin mice, immortalized normal human colon epithelial cells (HCEC) as well as murine embryonic fibroblasts (MEFs). RESULTS: Immunohistochemistry staining results established that EGFR overexpression is an early event in colorectal tumorigenesis, which can be greatly attenuated by regular use of aspirin. Importantly, EGFR and COX-2 were co-overexpressed and co-localized with each other in FAP patients. Further mechanistic studies revealed that COX-2 overexpression triggers the activation of the c-Jun-dependent transcription factor, activator protein-1 (AP-1), which binds to the Egfr promoter. Binding facilitates the cellular accumulation of EGFR and lowers the threshold required for pre-neoplastic cells to undergo transformation. CONCLUSION: Aspirin might exert its chemopreventive activity against CRC, at least partially, by normalizing EGFR expression in gastrointestinal precancerous lesions.
RESUMO
Recent clinical trials raised concerns regarding the cardiovascular toxicity of selective cyclooxygenase-2 (COX-2) inhibitors and cyclooxygenase-1 (COX-1) is now being reconsidered as a target for chemoprevention. Our aims were to determine whether selective COX-1 inhibition could delay or prevent cancer development and also clarify the underlying mechanisms. Data clearly showed that COX-1 was required for maintenance of malignant characteristics of colon cancer cells or tumor promoter-induced transformation of preneoplastic cells. We also successfully applied a ligand-docking computational method to identify a novel selective COX-1 inhibitor, 6-C-(E-phenylethenyl)-naringenin (designated herein as 6CEPN). 6CEPN could bind to COX-1 and specifically inhibited its activity both in vitro and ex vivo. In colorectal cancer cells, it potently suppressed anchorage-independent growth by inhibiting COX-1 activity. 6CEPN also effectively suppressed tumor growth in a 28-day colon cancer xenograft model without any obvious systemic toxicity. Taken together, COX-1 plays a critical role in human colorectal carcinogenesis, and this specific COX-1 inhibitor merits further investigation as a potential preventive agent against colorectal cancer.
Assuntos
Neoplasias Colorretais/tratamento farmacológico , Ciclo-Oxigenase 1/metabolismo , Inibidores de Ciclo-Oxigenase/farmacologia , Flavanonas/farmacologia , Animais , Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/patologia , Neoplasias Colorretais/prevenção & controle , Modelos Animais de Doenças , Feminino , Células HT29 , Humanos , Masculino , Camundongos , Camundongos Nus , Transfecção , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Recent clinical trials raised concerns regarding the cardiovascular toxicity of selective cyclooxygenase-2 (COX-2) inhibitors. Many active dietary factors are reported to suppress carcinogenesis by targeting COX-2. A major question was accordingly raised: why has the lifelong use of phytochemicals that likely inhibit COX-2 presumably not been associated with adverse cardiovascular side effects. To answer this question, we selected a library of dietary-derived phytochemicals and evaluated their potential cardiovascular toxicity in human umbilical vein endothelial cells. Our data indicated that the possibility of cardiovascular toxicity of these dietary phytochemicals was low. Further mechanistic studies revealed that the actions of these phytochemicals were similar to aspirin in that they mainly inhibited COX-1 rather than COX-2, especially at low doses.
Assuntos
Ciclo-Oxigenase 1/metabolismo , Ciclo-Oxigenase 2/metabolismo , Inibidores de Ciclo-Oxigenase/farmacologia , Compostos Fitoquímicos/farmacologia , 6-Cetoprostaglandina F1 alfa/farmacologia , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Ciclo-Oxigenase 1/genética , Ciclo-Oxigenase 2/genética , Inibidores de Ciclo-Oxigenase/toxicidade , Ativação Enzimática/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Concentração Inibidora 50 , Camundongos , Camundongos Knockout , Óxido Nítrico/biossíntese , Compostos Fitoquímicos/toxicidade , Tromboxano B2/farmacologiaRESUMO
Plant-based polyphenols (i.e., phytochemicals) have been used as treatments for human ailments for centuries. The mechanisms of action of these plant-derived compounds are now a major area of investigation. Thousands of phytochemicals have been isolated, and a large number of them have shown protective activities or effects in different disease models. Using conventional approaches to select the best single or group of best chemicals for studying the effectiveness in treating or preventing disease is extremely challenging. We have developed and used computational-based methodologies that provide efficient and inexpensive tools to gain further understanding of the anticancer and therapeutic effects exerted by phytochemicals. Computational methods involving virtual screening, shape and pharmacophore analysis and molecular docking have been used to select chemicals that target a particular protein or enzyme and to determine potential protein targets for well-characterized as well as for novel phytochemicals.
Assuntos
Anticarcinógenos/metabolismo , Anticarcinógenos/farmacologia , Biologia Computacional , Flavonoides/metabolismo , Flavonoides/farmacologia , Terapia de Alvo Molecular , Anticarcinógenos/química , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Flavonoides/química , Humanos , Modelos Moleculares , Proteínas de Neoplasias/química , Proteínas de Neoplasias/metabolismo , Conformação Proteica , Interface Usuário-ComputadorRESUMO
Skin cancer is one of the most commonly diagnosed cancers in the United States. Taxifolin reportedly exerts multiple biologic effects, but the molecular mechanisms and direct target(s) of taxifolin in skin cancer chemoprevention are still unknown. In silico computer screening and kinase profiling results suggest that the EGF receptor (EGFR), phosphoinositide 3-kinase (PI3K), and Src are potential targets for taxifolin. Pull-down assay results showed that EGFR, PI3K, and Src directly interacted with taxifolin in vitro, whereas taxifolin bound to EGFR and PI3K, but not to Src in cells. ATP competition and in vitro kinase assay data revealed that taxifolin interacted with EGFR and PI3K at the ATP-binding pocket and inhibited their kinase activities. Western blot analysis showed that taxifolin suppressed UVB-induced phosphorylation of EGFR and Akt, and subsequently suppressed their signaling pathways in JB6 P+ mouse skin epidermal cells. Expression levels and promoter activity of COX-2 and prostaglandin E(2) (PGE(2)) generation induced by UVB were also attenuated by taxifolin. The effect of taxifolin on UVB-induced signaling pathways and PGE(2) generation was reduced in EGFR knockout murine embryonic fibroblasts (MEF) compared with EGFR wild-type MEFs. Taxifolin also inhibited EGF-induced cell transformation. Importantly, topical treatment of taxifolin to the dorsal skin significantly suppressed tumor incidence, volume, and multiplicity in a solar UV (SUV)-induced skin carcinogenesis mouse model. Further analysis showed that the taxifolin-treated group had a substantial reduction in SUV-induced phosphorylation of EGFR and Akt in mouse skin. These results suggest that taxifolin exerts chemopreventive activity against UV-induced skin carcinogenesis by targeting EGFR and PI3K.
Assuntos
Antineoplásicos/farmacologia , Receptores ErbB/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Quercetina/análogos & derivados , Neoplasias Cutâneas/prevenção & controle , Animais , Western Blotting , Transformação Celular Neoplásica/efeitos dos fármacos , Modelos Animais de Doenças , Receptores ErbB/química , Feminino , Camundongos , Camundongos Knockout , Modelos Moleculares , Fosfatidilinositol 3-Quinases/química , Estrutura Quaternária de Proteína , Quercetina/farmacologia , Transdução de Sinais/efeitos dos fármacos , Neoplasias Cutâneas/metabolismo , Raios UltravioletaRESUMO
Ultraviolet (UV) irradiation is the leading factor in the development of skin cancer, prompting great interest in chemopreventive agents for this disease. In this study, we report the discovery of norathyriol, a plant-derived chemopreventive compound identified through an in silico virtual screening of the Chinese Medicine Library. Norathyriol is a metabolite of mangiferin found in mango, Hypericum elegans, and Tripterospermum lanceolatum and is known to have anticancer activity. Mechanistic investigations determined that norathyriol acted as an inhibitor of extracellular signal-regulated kinase (ERK)1/2 activity to attenuate UVB-induced phosphorylation in mitogen-activated protein kinases signaling cascades. We confirmed the direct and specific binding of norathyriol with ERK2 through a cocrystal structural analysis. The xanthone moiety in norathyriol acted as an adenine mimetic to anchor the compound by hydrogen bonds to the hinge region of the protein ATP-binding site on ERK2. Norathyriol inhibited in vitro cell growth in mouse skin epidermal JB6 P+ cells at the level of G(2)-M phase arrest. In mouse skin tumorigenesis assays, norathyriol significantly suppressed solar UV-induced skin carcinogenesis. Further analysis indicated that norathyriol mediates its chemopreventive activity by inhibiting the ERK-dependent activity of transcriptional factors AP-1 and NF-κB during UV-induced skin carcinogenesis. Taken together, our results identify norathyriol as a safe new chemopreventive agent that is highly effective against development of UV-induced skin cancer.
Assuntos
MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , Neoplasias Induzidas por Radiação/prevenção & controle , Inibidores de Proteínas Quinases/farmacologia , Neoplasias Cutâneas/prevenção & controle , Luz Solar , Xantenos/farmacologia , Animais , Western Blotting , MAP Quinases Reguladas por Sinal Extracelular/química , Feminino , Camundongos , Modelos Moleculares , Neoplasias Induzidas por Radiação/etiologia , Neoplasias Cutâneas/etiologiaRESUMO
The cancer microenvironment affects cancer cell proliferation and growth. Embryonic stem (ES)-preconditioned 3-dimensional (3-D) culture of cancer cells induces cancer cell reprogramming and results in a change in cancer cell properties such as differentiation and migration in skin melanoma. However, the mechanism has not yet been clarified. Using the ES-preconditioned 3-D microenvironment model, we provide evidence showing that the ES microenvironment inhibits proliferation and anchorage-independent growth of SK-MEL-28 melanoma cells. We also found that the ES microenvironment suppresses telomerase activity and thereby induces senescence in SK-MEL-28 cells. Furthermore, we observed that gremlin, an antagonist of BMP4, is secreted from ES cells and plays an important role in cellular senescence. Knocking down gremlin in the ES microenvironment increases proliferation and anchorage-independent growth of SK-MEL-28 melanoma cells. Taken together, these results demonstrated that gremlin is a crucial factor responsible for abrogating melanoma properties in the ES-preconditioned 3-D microenvironment.