RESUMO
Androgen ablation therapy is the primary treatment for metastatic prostate cancer. However, this therapy is associated with several undesired side-effects, including increased risk of cardiovascular diseases. To study if termination of long-term androgen ablation and restoration of testosterone levels could suppress the growth of relapsed hormone-refractory prostate tumors, we implanted testosterone pellets in castrated nude mice carrying androgen receptor (AR)-positive LNCaP 104-R2 cells, which relapsed from androgen-dependent LNCaP 104-S cells after long-term androgen deprivation. 104-R2 tumor xenografts regressed after testosterone pellets were implanted. Of 33 tumors, 24 adapted to elevation of testosterone level and relapsed as androgen-insensitive tumors. Relapsed tumors (R2Ad) expressed less AR and prostate-specific antigen. We then studied the molecular mechanism underlying the androgenic regulation of prostate cancer cell proliferation. Androgen suppresses proliferation of 104-R2 by inducing G(1) cell cycle arrest through reduction of S-phase kinase-associated protein 2 (Skp2) and c-Myc, and induction of p27(Kip1). 104-R2 cells adapted to androgen treatment and the adapted cells, R2Ad, were androgen-insensitive cells with a slower growth rate and low protein level of AR, high levels of c-Myc and Skp2, and low levels of p27(Kip1). Nuclear AR and prostate-specific antigen expression is present in 104-R2 cells but not R2Ad cells when androgen is absent. Overexpression of AR in R2Ad cells regenerated an androgen-repressed phenotype; knockdown of AR in 104-R2 cells generated an androgen-insensitive phenotype. Overexpression of Skp2 and c-Myc in 104-R2 cells blocked the growth inhibition caused by androgens. We concluded that androgens cause growth inhibition in LNCaP 104-R2 prostate cancer cells through AR, Skp2, and c-Myc.
Assuntos
Adenocarcinoma/patologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Proteínas de Neoplasias/fisiologia , Neoplasias da Próstata/patologia , Proteínas Proto-Oncogênicas c-myc/fisiologia , Proteínas Quinases Associadas a Fase S/fisiologia , Adenocarcinoma/metabolismo , Adenocarcinoma/secundário , Antagonistas de Androgênios/farmacologia , Antagonistas de Androgênios/uso terapêutico , Anilidas/farmacologia , Anilidas/uso terapêutico , Animais , Ciclo Celular/efeitos dos fármacos , Divisão Celular , Linhagem Celular Tumoral/efeitos dos fármacos , Linhagem Celular Tumoral/metabolismo , Linhagem Celular Tumoral/patologia , Inibidor de Quinase Dependente de Ciclina p27/biossíntese , Inibidor de Quinase Dependente de Ciclina p27/genética , Inibidor de Quinase Dependente de Ciclina p27/fisiologia , Implantes de Medicamento , Humanos , Metástase Linfática , Masculino , Metribolona/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , Nitrilas/farmacologia , Nitrilas/uso terapêutico , Orquiectomia , Neoplasias da Próstata/metabolismo , Proteínas Proto-Oncogênicas c-myc/biossíntese , Proteínas Proto-Oncogênicas c-myc/genética , Receptores Androgênicos , Proteínas Quinases Associadas a Fase S/biossíntese , Proteínas Quinases Associadas a Fase S/genética , Testosterona/administração & dosagem , Testosterona/farmacologia , Compostos de Tosil/farmacologia , Compostos de Tosil/uso terapêutico , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Prostate cancer is the most frequently diagnosed non-cutaneous tumor of men in Western countries. While surgery is often successful for organ-confined prostate cancer, androgen ablation therapy is the primary treatment for metastatic prostate cancer. However, this therapy is associated with several undesired side-effects, including increased risk of cardiovascular diseases. Shortening the period of androgen ablation therapy may benefit prostate cancer patients. Intermittent Androgen Deprivation therapy improves quality of life, reduces toxicity and medical costs, and delays disease progression in some patients. Cell culture and xenograft studies using androgen receptor (AR)-positive castration-resistant human prostate cancers cells (LNCaP, ARCaP, and PC-3 cells over-expressing AR) suggest that androgens may suppress the growth of AR-rich prostate cancer cells. Androgens cause growth inhibition and G1 cell cycle arrest in these cells by regulating c-Myc, Skp2, and p27Kip via AR. Higher dosages of testosterone cause greater growth inhibition of relapsed tumors. Manipulating androgen/AR signaling may therefore be a potential therapy for AR-positive advanced prostate cancer.
Assuntos
Proliferação de Células/efeitos dos fármacos , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Neoplasias da Próstata/tratamento farmacológico , Receptores Androgênicos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Testosterona/farmacologia , Animais , Linhagem Celular Tumoral , Inibidor de Quinase Dependente de Ciclina p27/metabolismo , Ensaio de Imunoadsorção Enzimática , Humanos , Masculino , Camundongos , Camundongos Nus , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Quinases Associadas a Fase S/metabolismo , Testosterona/uso terapêuticoRESUMO
It has been previously observed that low-density lipoprotein receptor knockout (LDLR--/--) mice fed a Western-type diet without cholate and given the liver X receptor agonist T1317 develop a persistent and enhanced hypertriglyceridemia. In contrast, LDLR--/-- mice fed a Paigen diet with cholate exhibit only a transient increase in plasma triglycerides when given T1317. Cholate as an activator of farnesoid X receptor may attenuate T1317-induced triglyceridemia. To determine if cholate was responsible for this transient nature of the hypertriglyceridemia, we orally administered T1317 to LDLR--/-- mice fed a modified Paigen diet without cholate. T1317 transiently elevated plasma triglycerides by increasing plasma very-low-density lipoprotein. Cholesterol and triglyceride levels in plasma very-low-density lipoprotein in T1317-treated mice decreased from peak levels to levels found in vehicle-treated mice after 8 weeks of treatment. A gradual decline of hepatic cholesterol and a transient increase in hepatic triglycerides were also observed in T1317-treated mice. T1317 only transiently activated the expression of genes related to liver de novo lipogenesis, whereas genes related to lipid metabolism were induced in T1317-treated mice, including a gradual increase in plasma lipoprotein lipase activity. Atheroprotective effects of T1317 were observed in the innominate artery and aortic arch but not in the aortic sinus. This work indicates that some component(s) in the Paigen diet other than cholate affect the T1317-induced gene expression profile and ameliorate its effects on lipid synthesis, which lead to hypertriglyceridemia and fatty liver. These findings are important for liver X receptor-related pharmaceutical development for the treatment of cardiovascular disease.
Assuntos
Colatos/administração & dosagem , Gorduras na Dieta/administração & dosagem , Hidrocarbonetos Fluorados/administração & dosagem , Receptores Nucleares Órfãos/agonistas , Receptores de LDL/deficiência , Sulfonamidas/administração & dosagem , Animais , Perfilação da Expressão Gênica/métodos , Receptores X do Fígado , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Nucleares Órfãos/fisiologia , Receptores de LDL/genéticaRESUMO
Liver X receptor (LXR) agonists have the potential to treat atherosclerosis based on their ability to enhance reverse cholesterol transport. However, their side effects, such as induction of liver lipogenesis and triglyceridemia, may limit their pharmaceutical development. In contrast to the nonsteroidal LXR agonist N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)ethyl]phenyl]-benzenesulfonamide (T0901317), 3alpha, 6alpha, 24-trihydroxy-24, 24-di(trifluoromethyl)-5beta-cholane (ATI-829), a novel potent synthetic steroidal LXR agonist, was a poor inducer of sterol regulatory element-binding protein 1c expression in hepatoma HepG2 cells, whereas both compounds increased ABCA1 expression in macrophage THP-1 cells. In male low-density lipoprotein receptor-deficient mice, ATI-829 selectively activated LXR target gene expression in mouse intestines and macrophages but not in the liver. A significant increase in liver triglyceride and plasma triglyceriderich small very low-density lipoprotein (VLDL) was observed in T0901317 but not ATI-829-treated mice. Compared with vehicle-treated mice, atherosclerosis development was significantly inhibited in the innominate artery after treatment with either compound. However, in the aortic root, inhibition of atherosclerosis was only observed in the right (right coronary artery-associated sinus) but not the left coronary-related sinus (left coronary artery-associated sinus; LC) of mice treated with either compound. Lesions in the innominate artery were less complex after treatment with either compound and contained mostly macrophage foam cells. In contrast, LC lesions were more complex and had a large collagen-positive fibrous cap and less macrophage foam cell area after treatment with either compound. The T0901317-induced hypertriglyceridemia was accompanied by an increase in small triglyceride-rich VLDL that may influence LXR agonist-mediated antiatherosclerotic effects at certain vascular sites. ATI-829, by selectively activating LXR in certain tissues without inducing hypertriglyceridemia, is a good candidate for drug development.
Assuntos
Aterosclerose/tratamento farmacológico , Proteínas de Ligação a DNA/agonistas , Hidroxiesteroides/farmacologia , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores de LDL/deficiência , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Apolipoproteínas E/genética , Linhagem Celular , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Hidroxiesteroides/farmacocinética , Lipoproteínas/genética , Lipoproteínas LDL/sangue , Lipoproteínas VLDL/sangue , Receptores X do Fígado , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Especificidade de Órgãos , Receptores Nucleares Órfãos , Triglicerídeos/sangueRESUMO
Androgen-dependent human LNCaP 104-S tumor xenografts progressed to androgen-independent relapsed tumors (104-Rrel) in athymic mice after castration. The growth of 104-Rrel tumors was suppressed by testosterone. However, 104-Rrel tumors adapted to androgen and regrew as androgen-stimulated 104-Radp tumors. Androgen receptor expression in tumors and serum prostate-specific antigen increased during progression from 104-S to 104-Rrel but decreased during transition from 104-Rrel to 104-Radp. Expression of genes related to liver X receptor (LXR) signaling changed during progression. LXRalpha, LXRbeta, ATP-binding cassette transporter A1 (ABCA1), and sterol 27-hydroxylase decreased during progression from 104-S to 104-Rrel. These coordinated changes in LXR signaling in mice during progression are consistent with our previous findings that reduction of ABCA1 gene expression stimulates proliferation of LNCaP cells. To test if attenuation of LXR signaling may enhance prostate cancer progression from an androgen-dependent state to an androgen-independent state, castrated mice carrying 104-S tumors were given the synthetic LXR agonist T0901317 by gavage. T0901317 delayed progression from 104-S to 104-Rrel tumors. Based on our in vivo model, androgen is beneficial for the treatment of androgen-independent androgen receptor-rich prostate cancer and modulation of LXR signaling may be a potentially useful therapy for prostate cancer.
Assuntos
Androgênios/farmacologia , Proteínas de Ligação a DNA/agonistas , Receptores Citoplasmáticos e Nucleares/agonistas , Sulfonamidas/farmacologia , Animais , Processos de Crescimento Celular , Colesterol/farmacologia , Progressão da Doença , Humanos , Hidrocarbonetos Fluorados , Receptores X do Fígado , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Neoplasias Hormônio-Dependentes/tratamento farmacológico , Neoplasias Hormônio-Dependentes/metabolismo , Neoplasias Hormônio-Dependentes/patologia , Orquiectomia , Receptores Nucleares Órfãos , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Receptores Androgênicos/biossíntese , Receptores Androgênicos/metabolismo , Testosterona/sangue , Propionato de Testosterona/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Most prostate cancer patients develop androgen-independent recurrent prostate tumors a few years after androgen ablation therapy. No therapy, however, has been shown to substantially extend survival in these patients. Previously, we reported that androgen suppresses the growth of androgen-independent LNCaP prostate tumor cells both in vitro and in vivo. In cell culture, androgen receptor (AR)-rich androgen-independent LNCaP 104-R1 cells adapt to growth suppression by androgen and then their growth is androgen stimulated. Because maintaining androgen dependency of prostate tumor cells should prolong the usefulness of androgen ablation therapy, we determined if androgen-independent prostate tumors would revert to an androgen-stimulated phenotype in vivo upon androgen treatment. Growth of the LNCaP 104-R1 tumors was suppressed by androgen, but tumors then adapted to suppression by androgen and growth became androgen stimulated. Tumor AR and prostate-specific antigen mRNA and protein were initially high in 104-R1 tumors but decreased during adaptation. Subsequent removal of androgen decreased the serum prostate-specific antigen level further and stopped the growth of the adapted tumors. Because androgen caused growth suppression and then reversion of androgen-independent tumors to an androgen-stimulated phenotype and because the growth of androgen-stimulated tumors could be restrained by androgen ablation, these results suggest a novel therapy for AR-positive androgen-independent prostate cancer.
Assuntos
Neoplasias Hormônio-Dependentes/patologia , Neoplasias da Próstata/patologia , Testosterona/farmacologia , Animais , Processos de Crescimento Celular/efeitos dos fármacos , Processos de Crescimento Celular/fisiologia , Linhagem Celular Tumoral , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Transplante de Neoplasias , Neoplasias Hormônio-Dependentes/sangue , Neoplasias Hormônio-Dependentes/metabolismo , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/sangue , Neoplasias da Próstata/metabolismo , Receptores Androgênicos/biossíntese , Receptores Androgênicos/metabolismo , Transplante HeterólogoRESUMO
Liver X receptors function as central transcriptional regulators for lipid homeostasis, for which agonists have been developed as potential drugs for treatment of cardiovascular diseases and metabolic syndromes. Because dysregulation of lipid metabolism has been implicated in sex hormone-dependent cancers, we investigated the effect of liver X receptor agonists on prostate and breast cancer cell proliferation. Treatment of human prostate cancer LNCaP cell lines with the synthetic liver X receptor agonist T0901317 decreased the percentage of S-phase cells in a dose-dependent manner and increased the expression of cyclin-dependent kinase inhibitor p27(Kip-1) (p27). Knockdown of p27 by RNA interference blocks T0901317-induced growth inhibition, suggesting that p27 expression plays a crucial role in this signaling. Liver X receptor agonists also inhibited the proliferation of other prostate and breast cancer cell lines. The level of liver X receptor alpha expression correlated directly with sensitivity to growth inhibition by liver X receptor agonists. Retroviral expression of liver X receptor alpha in human breast cancer MDA-MB435S cells, which express low levels of endogenous liver X receptors and are insensitive to T0901317, sensitized these cells to T0901317. Consistent with our observations in LNCaP cells, T0901317 induces dramatic up-regulation of p27 in liver X receptor alpha-overexpressing MDA-MB435S cells. Furthermore, oral administration of T0901317 inhibited the growth of LNCaP tumors in athymic nude mice. Based on these results, modulation of the liver X receptor signaling pathway is a new target for controlling tumor cell proliferation; therefore, liver X receptor agonists may have utility as antitumorigenic agents.
Assuntos
Anticolesterolemiantes/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Receptores Citoplasmáticos e Nucleares/agonistas , Animais , Proteínas de Ciclo Celular/metabolismo , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Inibidor de Quinase Dependente de Ciclina p27 , Proteínas de Ligação a DNA , Humanos , Hidrocarbonetos Fluorados , Receptores X do Fígado , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Receptores Nucleares Órfãos , Neoplasias da Próstata/patologia , Receptores Citoplasmáticos e Nucleares/fisiologia , Sulfonamidas , Proteínas Supressoras de Tumor/metabolismoRESUMO
Alteration of lipid metabolism is commonly observed in sex hormone-dependent cancer cells, yet its mechanistic involvement in cancer cell proliferation and progression is unclear. We have found that the expression of the cholesterol transporter, ATP-binding cassette transporter A1 (ABCA1), was 15- to 20-fold higher in androgen-dependent than in androgen-independent LNCaP human prostate cancer cells, indicating a possible relationship between the expression levels of ABCA1 and prostate cancer progression. On the basis of real-time quantitative PCR and Western blot analysis, expression of ABCA1 in androgen-dependent cells was inhibited by androgen. The antiandrogen Casodex blocked the effect of androgen, implicating the androgen receptor in regulation of ABCA1 expression by androgens. Using an ABCA1 promoter-reporter gene assay, androgenic suppression was observed at the transcriptional level in androgen-dependent but not in androgen-independent prostate cancer cells. ABCA1 appears to have a role in modulating cell proliferation because knockdown of ABCA1 expression by RNA interference in androgen-dependent cells increased their rate of proliferation. Therefore, a suppressive effect of androgen on ABCA1 expression may be one of the mechanisms by which androgens regulate proliferation in prostate cancer cells. Attenuated ABCA1 expression in androgen-independent cells thus may contribute, in part, to prostate cancer progression.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Androgênios/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Neoplasias da Próstata/metabolismo , Transportador 1 de Cassete de Ligação de ATP , Sequência de Bases , Linhagem Celular Tumoral , Humanos , Masculino , Dados de Sequência Molecular , Regiões Promotoras Genéticas , RNA Mensageiro/análiseRESUMO
The farnesoid X receptor (FXR) is activated by bile acids, natural agonists for this nuclear receptor. FXR-target genes play important roles in cholesterol and lipid metabolism. We have found that a series of 5beta-cholanic acid derivatives, even though without a hydroxyl group or any other substituent on the steroidal rings, can activate FXR more potently than hydroxylated bile acids in a reporter gene assay. The most potent compound among these derivatives, N-methyl-5beta-glycocholanic acid (NMGCA), induces the formation of receptor/coactivator complex in a gel-shift assay and also increases the expression of FXR target genes in human hepatoma HepG2 cells. Furthermore, in rats, NMGCA causes hypolipidemic effects as well as induction of the FXR target genes in liver. Our results suggest that NMGCA and its derivatives are important FXR activators in the study of the physiological functions of FXR and are potentially useful as pharmaceutical agents for treatment of cholesterol and lipid-related diseases.
Assuntos
Ácidos Cólicos/farmacologia , Proteínas de Ligação a DNA/agonistas , Fatores de Transcrição/agonistas , Animais , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Linhagem Celular Tumoral , Colesterol/sangue , Ácidos Cólicos/administração & dosagem , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Receptores X do Fígado , Masculino , Camundongos , Receptores Nucleares Órfãos , RNA Mensageiro/biossíntese , Ratos , Ratos Endogâmicos F344 , Receptores Citoplasmáticos e Nucleares , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína de Ligação a Elemento Regulador de Esterol 1 , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Triglicerídeos/sangueRESUMO
The enzyme steroid 5 alpha-reductase (EC 1.3.99.5) catalyzes the NADPH-dependent reduction of the double bond of a variety of 3-oxo-Delta(4) steroids including the conversion of testosterone to 5 alpha-dihydrotestosterone. In humans, 5 alpha-reductase activity is critical for certain aspects of male sexual differentiation, and may be involved in the development of benign prostatic hyperplasia, alopecia, hirsutism, and prostate cancer. Certain natural products contain components that are inhibitors of 5 alpha-reductase, such as the green tea catechin (-)-epigallocatechin gallate (EGCG). EGCG shows potent inhibition in cell-free but not in whole-cell assays of 5 alpha-reductase. Replacement of the gallate ester in EGCG with long-chain fatty acids produced potent 5 alpha-reductase inhibitors that were active in both cell-free and whole-cell assay systems. Other flavonoids that were potent inhibitors of the type 1 5alpha-reductase include myricetin, quercitin, baicalein, and fisetin. Biochanin A, daidzein, genistein, and kaempferol were much better inhibitors of the type 2 than the type 1 isozyme. Several other natural and synthetic polyphenolic compounds were more effective inhibitors of the type 1 than the type 2 isozyme, including alizarin, anthrarobin, gossypol, nordihydroguaiaretic acid, caffeic acid phenethyl ester, and octyl and dodecyl gallates. The presence of a catechol group was characteristic of almost all inhibitors that showed selectivity for the type 1 isozyme of 5 alpha-reductase. Since some of these compounds are consumed as part of the normal diet or in supplements, they have the potential to inhibit 5 alpha-reductase activity, which may be useful for the prevention or treatment of androgen-dependent disorders. However, these compounds also may adversely affect male sexual differentiation.
Assuntos
Inibidores de 5-alfa Redutase , Inibidores Enzimáticos/farmacologia , Flavonoides , Fenóis/farmacologia , Polímeros/farmacologia , 3-Oxo-5-alfa-Esteroide 4-Desidrogenase/metabolismo , Animais , Catequina/análogos & derivados , Catequina/química , Catequina/farmacologia , Extratos Celulares , Sistema Livre de Células , Inibidores Enzimáticos/química , Humanos , Cinética , Fenóis/química , Polímeros/química , Ratos , Relação Estrutura-Atividade , Chá/químicaRESUMO
The majority of prostate cancer (PCa) patient receiving androgen ablation therapy eventually develop castration-resistant prostate cancer (CRPC). We previously reported that androgen treatment suppresses Skp2 and c-Myc through androgen receptor (AR) and induced G1 cell cycle arrest in androgen-independent LNCaP 104-R2 cells, a late stage CRPC cell line model. However, the mechanism of androgenic regulation of Skp2 in CRPC cells was not fully understood. In this study, we investigated the androgenic regulation of Skp2 in two AR-positive CRPC cell line models, the LNCaP 104-R1 and PC-3AR Cells. The former one is an early stage androgen-independent LNCaP cells, while the later one is PC-3 cells re-expressing either wild type AR or mutant LNCaP AR. Proliferation of LNCaP 104-R1 and PC-3AR cells is not dependent on but is suppressed by androgen. We observed in this study that androgen treatment reduced protein expression of Cdk2, Cdk7, Cyclin A, cyclin H, Skp2, c-Myc, and E2F-1; lessened phosphorylation of Thr14, Tyr15, and Thr160 on Cdk2; decreased activity of Cdk2; induced protein level of p27(Kip1); and caused G1 cell cycle arrest in LNCaP 104-R1 cells and PC-3AR cells. Overexpression of Skp2 protein in LNCaP 104-R1 or PC-3AR cells partially blocked accumulation of p27(Kip1) and increased Cdk2 activity under androgen treatment, which partially blocked the androgenic suppressive effects on proliferation and cell cycle. Analyzing on-line gene array data of 214 normal and PCa samples indicated that gene expression of Skp2, Cdk2, and cyclin A positively correlates to each other, while Cdk7 negatively correlates to these genes. These observations suggested that androgen suppresses the proliferation of CRPC cells partially through inhibition of Cyclin A, Cdk2, and Skp2.
Assuntos
Androgênios/fisiologia , Proliferação de Células/fisiologia , Ciclina A/antagonistas & inibidores , Quinase 2 Dependente de Ciclina/antagonistas & inibidores , Orquiectomia , Neoplasias da Próstata/patologia , Proteínas Quinases Associadas a Fase S/antagonistas & inibidores , Linhagem Celular Tumoral , Humanos , MasculinoRESUMO
Oxysterols are oxidation products of cholesterol. Cholestane-3ß, 5α, 6ß-triol (abbreviated as triol) is one of the most abundant and active oxysterols. Here, we report that triol exhibits anti-cancer activity against human prostate cancer cells. Treatment of cells with triol dose-dependently suppressed proliferation of LNCaP CDXR-3, DU-145, and PC-3 human prostate cancer cells and reduced colony formation in soft agar. Oral administration of triol at 20 mg/kg daily for three weeks significantly retarded the growth of PC-3 xenografts in nude mice. Flow cytometric analysis revealed that triol treatment at 10-40 µM caused G1 cell cycle arrest while the TUNEL assay indicated that triol treatment at 20-40 µM induced apoptosis in all three cell lines. Micro-Western Arrays and traditional Western blotting methods indicated that triol treatment resulted in reduced expression of Akt1, phospho-Akt Ser473, phospho-Akt Thr308, PDK1, c-Myc, and Skp2 protein levels as well as accumulation of the cell cycle inhibitor p27(Kip). Triol treatment also resulted in reduced Akt1 protein expression in PC-3 xenografts. Overexpression of Skp2 in PC-3 cells partially rescued the growth inhibition caused by triol. Triol treatment suppressed migration and invasion of DU-145, PC-3, and CDXR-3 cells. The expression levels of proteins associated with epithelial-mesenchymal transition as well as focal adhesion kinase were affected by triol treatment in these cells. Triol treatment caused increased expression of E-cadherin protein levels but decreased expression of N-cadherin, vimentin, Slug, FAK, phospho-FAK Ser722, and phospho-FAK Tyr861 protein levels. Confocal laser microscopy revealed redistribution of ß-actin and α-tubulin at the periphery of the CDXR-3 and DU-145 cells. Our observations suggest that triol may represent a promising therapeutic agent for advanced metastatic prostate cancer.
Assuntos
Antineoplásicos/farmacologia , Movimento Celular/efeitos dos fármacos , Colestanóis/farmacologia , Neoplasias da Próstata/metabolismo , Actinas/metabolismo , Androgênios/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Expressão Gênica , Humanos , Receptores X do Fígado , Masculino , Camundongos , Invasividade Neoplásica , Receptores Nucleares Órfãos/agonistas , Fosforilação , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , Proteoma , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Quinases Associadas a Fase S/genética , Transdução de Sinais , Tubulina (Proteína)/metabolismo , Carga Tumoral/efeitos dos fármacos , Ensaio Tumoral de Célula-Tronco , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Caffeic acid phenethyl ester (CAPE) is a bioactive component derived from honeybee hive propolis. CAPE has been shown to have antimitogenic, anticarcinogenic, and other beneficial medicinal properties. Many of its effects have been shown to be mediated through its inhibition of NF-κB signaling pathways. We took a systematic approach to uncover the effects of CAPE from hours to days on the signaling networks in human prostate cancer cells. We observed that CAPE dosage dependently suppressed the proliferation of LNCaP, DU-145, and PC-3 human prostate cancer cells. Administration of CAPE by gavage significantly inhibited the tumor growth of LNCaP xenografts in nude mice. Using LNCaP cells as a model system, we examined the effect of CAPE on gene expression, protein signaling, and transcriptional regulatory networks using micro-Western arrays and PCR arrays. We built a model of the impact of CAPE on cell signaling which suggested that it acted through inhibition of Akt-related protein signaling networks. Overexpression of Akt1 or c-Myc, a downstream target of Akt signaling, significantly blocked the antiproliferative effects of CAPE. In summary, our results suggest that CAPE administration may be useful as an adjuvant therapy for prostate and potentially other types of cancers that are driven by the p70S6K and Akt signaling networks.
Assuntos
Ácidos Cafeicos/farmacologia , Carcinoma/patologia , Proliferação de Células/efeitos dos fármacos , Proteína Oncogênica v-akt/antagonistas & inibidores , Álcool Feniletílico/análogos & derivados , Neoplasias da Próstata/patologia , Proteínas Quinases S6 Ribossômicas 70-kDa/antagonistas & inibidores , Animais , Ácidos Cafeicos/uso terapêutico , Carcinoma/metabolismo , Carcinoma/prevenção & controle , Linhagem Celular Tumoral , Citotoxinas/farmacologia , Citotoxinas/uso terapêutico , Regulação para Baixo/efeitos dos fármacos , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Proteína Oncogênica v-akt/metabolismo , Álcool Feniletílico/farmacologia , Álcool Feniletílico/uso terapêutico , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/prevenção & controle , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND AND PURPOSE: Potent synthetic nonsteroidal liver X receptor (LXR) agonists like T0901317 induce triglyceridaemia and fatty liver, effects not observed with some natural and synthetic steroidal, relatively weak agonists of LXR. To determine if potency is responsible for the lack of side effects with some steroidal agonists, we investigated the in vivo effects of a novel steroidal LXR agonist, ATI-111, that is more potent than T0901317. EXPERIMENTAL APPROACH: Eight week old male LDLR(-/-) mice fed an atherogenic diet were orally treated with vehicle or ATI-111 at 3 and 5 mg·kg(-1) ·day(-1) for 8 weeks, and effects on plasma and liver lipid levels, expression of genes involved in lipid metabolism and on atherogenesis were analysed. KEY RESULTS: ATI-111 increased the expression of genes involved in lipid transport, such as ABCA1, ABCG1 and ABCG5/G8, in intestine and macrophages; decreased ABCG1, apoE; and slightly increased ABCA1 and ABCG5/G8 expression in liver. ATI-111 markedly increased sterol regulatory element-binding protein (SREBP)-1c mRNA in some tissues, whereas acetyl-coenzyme A carboxylase and fatty acid synthase expression was unaffected or only slightly increased in intestine and liver. ATI-111 inhibited the conversion of SREBP-1c precursor form to its active form. Compared with vehicle-treated mice, the levels of hepatic lipids and liver-secreted nascent lipoproteins were not altered, while a significant decrease in plasma cholesterol and triglyceride levels was observed in ATI-111-treated mice. ATI-111 significantly inhibited atherogenesis in three separate vascular sites. CONCLUSIONS AND IMPLICATIONS: ATI-111 is a promising candidate for further development as a treatment of certain vascular diseases as it lacks the significant side effects associated with nonsteroidal LXR agonists, the induction of fatty liver and hypertriglyceridaemia.
Assuntos
Aterosclerose/tratamento farmacológico , Hidroxiesteroides/farmacologia , Receptores Nucleares Órfãos/agonistas , Receptores de LDL/genética , Animais , Aterosclerose/fisiopatologia , Colesterol/sangue , Colesterol/metabolismo , Relação Dose-Resposta a Droga , Regulação da Expressão Gênica/efeitos dos fármacos , Hidroxiesteroides/administração & dosagem , Hidroxiesteroides/efeitos adversos , Mucosa Intestinal/metabolismo , Intestinos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Receptores X do Fígado , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Triglicerídeos/sangue , Triglicerídeos/metabolismoRESUMO
The effects of liver X receptor (LXR) agonists on plasma lipid homeostasis, especially triglyceride metabolism are controversial. Here we examined the effect of long-term activation of LXR on plasma lipid homeostasis in wild-type C57BL/6 and LDL receptor deficient (LDLR-/-) mice given the LXR agonist T0901317 for 4 weeks. LXR agonist treatment of wild-type mice decreased plasma total triglycerides by 35% due to a significant reduction of plasma VLDL triglycerides. In contrast, in LDLR-/- mice T0901317 treatment increased plasma total cholesterol and triglycerides. An increase in the level of smaller VLDL particles was also observed in T0901317-treated LDLR-/- mice. The changes in circulating lipoprotein profiles in response to T0901317 treatment in these two animal models reflect the balance between synthesis and secretion on the one hand and lipolysis and clearance on the other. In both models there was both an increase in VLDL production and secretion and in an increase in LPL production and activity in T0901317-treated animals. In wild-type mice lipolysis and clearance predominates, while in the absence of the LDLR, which plays a major role in the clearance of apoB-containing lipoproteins, the increased output predominates. The generation of elevated levels of small VLDL particles due to increased lipolysis may represent an additional risk factor for atherosclerosis.
Assuntos
Homeostase , Lipídeos/sangue , Lipoproteínas/metabolismo , Receptores Nucleares Órfãos/fisiologia , Animais , Receptores X do Fígado , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Triglicerídeos/sangueRESUMO
A series of 3-O-acylated (-)-epigallocatechins were synthesized and their inhibition of steroid 5α-reductase was studied. They were prepared from the reaction of EGCG with tert-butyldimethylsilyl chloride followed by reductive cleavage of the ester bond. The resultant (-)-epigallocatechins penta-O-tert-butyldimethylsilyl ether was esterified with different fatty acids then desilylated to provide the corresponding products. The activity of 3-O-acylated (-)-epigallocatechins increased with the increasing carbon numbers of the fatty acid moiety, reaching maximum for 16 carbon atoms (compound 4h) with an IC50 of 0.53 µM, which was â¼12-fold more potent than EGCG (IC50=6.29 µM). Introduction of monounsaturated fatty acid provided the most potent compound 6 (IC50=0.48 µM), which showed moderate anti-tumor activity in vivo.
Assuntos
3-Oxo-5-alfa-Esteroide 4-Desidrogenase/metabolismo , Inibidores de 5-alfa Redutase/farmacologia , Antineoplásicos/farmacologia , Catequina/análogos & derivados , Inibidores de 5-alfa Redutase/síntese química , Inibidores de 5-alfa Redutase/química , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Catequina/síntese química , Catequina/química , Catequina/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Masculino , Camundongos , Camundongos SCID , Modelos Moleculares , Estrutura Molecular , Estereoisomerismo , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), inhibits the development and progression of prostate cancer in TRAMP mice and in men. We examined the effects of EGCG on LNCaP human prostate cancer sublines 104-S, 104-R1 and R1Ad representing different progression stages of prostate cancer. EGCG suppressed cell proliferation, prostate specific antigen (PSA) expression, and AR transcriptional activity in the different LNCaP sublines. Intraperitoneal administration of EGCG also suppressed the growth of relapsing R1Ad tumors and decreased tumor-derived serum PSA. Effects of EGCG on tumor PSA expression have the potential to affect accurate monitoring of patient tumor burden by serum PSA measurements.
Assuntos
Catequina/análogos & derivados , Antígeno Prostático Específico/biossíntese , Neoplasias da Próstata/patologia , Receptores Androgênicos/metabolismo , Animais , Catequina/farmacologia , Linhagem Celular Tumoral , Proliferação de Células , Progressão da Doença , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias da Próstata/metabolismo , Recidiva , Transdução de Sinais , Transcrição GênicaRESUMO
Activation of liver X receptors (LXRs) has been reported to reduce atherosclerosis in mouse models. However, this can be associated with enhanced liver de novo lipogenesis and elevation of plasma triglyceride-rich VLDL, which may limit its clinical use. In this study, we administered orally the LXR agonist T0901317 to male LDLR-/- mice fed a Western diet. This induced a persistent enhanced hypertriglyceridemia by largely increasing plasma triglyceride-rich VLDL. T0901317 treatment decreased atherosclerosis with a much more pronounced response and dose dependence in the innominate artery than in the aortic sinus. Lesions in the innominate artery were less complex containing mostly macrophage foam cells in T0901317-treated mice. However, in the aortic root, a significant reduction of atherosclerosis was seen only in the right coronary-related aortic sinus (RC) of T0901317-treated mice. Increasing the dose of T0901317 did not extend atheroprotection to the other sinuses of the aortic root. Lesions in the RC were less complex both in T0901317 and vehicle-treated mice with macrophage foam cells predominating. On the other hand, in T0901317-treated mice, the left coronary-related sinus (LC) lesions while not reduced in size, were more complex with a large fibrous cap and necrotic core, more collagen-positive areas, and variable macrophage foam cell content compared to vehicle-treated mice. These data suggest that activation of LXR by T0901317 had differential anti-atherosclerotic effects in two arterial regions in mice with hypertriglyceridemia.
Assuntos
Aterosclerose/prevenção & controle , Tronco Braquiocefálico/patologia , Proteínas de Ligação a DNA/metabolismo , Hidrocarbonetos Fluorados/farmacologia , Receptores Citoplasmáticos e Nucleares/metabolismo , Seio Aórtico/patologia , Sulfonamidas/farmacologia , Animais , Aterosclerose/tratamento farmacológico , Células Espumosas/citologia , Regulação da Expressão Gênica , Hipertrigliceridemia/tratamento farmacológico , Lipídeos/química , Receptores X do Fígado , Macrófagos/citologia , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Receptores Nucleares ÓrfãosRESUMO
Bcl-2 is an anti-apoptotic oncoprotein and its protein levels are inversely correlated with prognosis in many cancers. However, the role of Bcl-2 in the progression of prostate cancer is not clear. Here we report that Bcl-2 is required for the progression of LNCaP prostate cancer cells from an androgen-dependent to an androgen-independent growth stage. The mRNA and protein levels of Bcl-2 are significantly increased in androgen-independent prostate cancer cells. shRNA-mediated gene silencing of Bcl-2 in androgen-independent prostate cancer cells promotes UV-induced apoptosis and suppresses the growth of prostate tumors in vivo. Growing androgen-dependent cells under androgen-deprivation conditions results in formation of androgen-independent colonies; and the transition from androgen-dependent to androgen-independent growth is blocked by ectopic expression of the Bcl-2 antagonist Bax or Bcl-2 shRNA. Thus, our results demonstrate that Bcl-2 is not only critical for the survival of androgen-independent prostate cancer cells, but is also required for the progression of prostate cancer cells from an androgen-dependent to an androgen-independent growth stage.
Assuntos
Androgênios/fisiologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Neoplasias da Próstata/patologia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Regulação para Cima/genética , Apoptose/genética , Linhagem Celular Tumoral , Progressão da Doença , Humanos , Masculino , Neoplasias da Próstata/genética , Proteínas Proto-Oncogênicas c-bcl-2/biossínteseRESUMO
Liver X receptors (LXRs) are important regulators of cholesterol, fatty acid, and glucose homeostasis. LXR agonists are effective for treatment of murine models of atherosclerosis, diabetes, and Alzheimer's disease. Recently we observed that LXR agonists suppressed proliferation of prostate and breast cancer cells in vitro and treatment of mice with the LXR agonist T0901317 suppressed the growth of prostate tumor xenografts. LXR agonists appear to cause G1 cell cycle arrest in cells by reducing expression of Skp2 and inducing the accumulation of p27(Kip). T0901317 induced expression of ATP-binding cassette transporter A1 (ABCA1) and delayed the progression of androgen-dependent human prostate tumor xenografts towards androgen-independency in mice. Phytosterols, the plant equivalent of mammalian cholesterol, have recently been shown to be agonists for LXRs. beta-Sitosterol and campesterol, the two most common phytosterols, suppressed proliferation of prostate and breast cancer cells. The anticancer activity of phytosterols may be due to LXR signaling. This review examines the potential use of LXR signaling as a therapeutic target in prostate and other cancers.