RESUMO
Dysfunctional telomeres suppress tumour progression by activating cell-intrinsic programs that lead to growth arrest. Increased levels of TRF2, a key factor in telomere protection, are observed in various human malignancies and contribute to oncogenesis. We demonstrate here that a high level of TRF2 in tumour cells decreased their ability to recruit and activate natural killer (NK) cells. Conversely, a reduced dose of TRF2 enabled tumour cells to be more easily eliminated by NK cells. Consistent with these results, a progressive upregulation of TRF2 correlated with decreased NK cell density during the early development of human colon cancer. By screening for TRF2-bound genes, we found that HS3ST4--a gene encoding for the heparan sulphate (glucosamine) 3-O-sulphotransferase 4--was regulated by TRF2 and inhibited the recruitment of NK cells in an epistatic relationship with TRF2. Overall, these results reveal a TRF2-dependent pathway that is tumour-cell extrinsic and regulates NK cell immunity.
Assuntos
Neoplasias da Mama/prevenção & controle , Neoplasias do Colo/prevenção & controle , Células Matadoras Naturais/imunologia , Linfócitos do Interstício Tumoral/imunologia , Melanoma Experimental/prevenção & controle , Sulfotransferases/metabolismo , Proteína 2 de Ligação a Repetições Teloméricas/metabolismo , Animais , Apoptose , Western Blotting , Neoplasias da Mama/imunologia , Neoplasias da Mama/metabolismo , Adesão Celular , Proliferação de Células , Neoplasias do Colo/imunologia , Neoplasias do Colo/metabolismo , Primers do DNA/química , Receptor com Domínio Discoidina 1 , Feminino , Citometria de Fluxo , Células HeLa , Humanos , Células Matadoras Naturais/metabolismo , Células Matadoras Naturais/patologia , Linfócitos do Interstício Tumoral/patologia , Melanoma Experimental/imunologia , Melanoma Experimental/metabolismo , Camundongos , Camundongos Nus , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase em Tempo Real , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sulfotransferases/genética , Proteína 2 de Ligação a Repetições Teloméricas/antagonistas & inibidores , Proteína 2 de Ligação a Repetições Teloméricas/genética , Células Tumorais CultivadasRESUMO
BACKGROUND: Dysregulation of many apoptotic related genes and androgens are critical in the development, progression, and treatment of prostate cancer. The differential sensitivity of tumour cells to TRAIL-induced apoptosis can be mediated by the modulation of surface TRAIL receptor expression related to androgen concentration. Our previous results led to the hypothesis that downregulation of TRAIL-decoy receptor DcR2 expression following androgen deprivation would leave hormone sensitive normal prostate cells vulnerable to the cell death signal generated by TRAIL via its pro-apoptotic receptors. We tested this hypothesis under pathological conditions by exploring the regulation of TRAIL-induced apoptosis related to their death and decoy receptor expression, as also to hormonal concentrations in androgen-sensitive human prostate cancer, LNCaP, cells. RESULTS: In contrast to androgen-insensitive PC3 cells, decoy (DcR2) and death (DR5) receptor protein expression was correlated with hormone concentrations and TRAIL-induced apoptosis in LNCaP cells. Silencing of androgen-sensitive DcR2 protein expression by siRNA led to a significant increase in TRAIL-mediated apoptosis related to androgen concentration in LNCaP cells. CONCLUSIONS: The data support the hypothesis that hormone modulation of DcR2 expression regulates TRAIL-induced apoptosis in LNCaP cells, giving insight into cell death induction in apoptosis-resistant hormone-sensitive tumour cells from prostate cancer. TRAIL action and DcR2 expression modulation are potentially of clinical value in advanced tumour treatment.
RESUMO
The apoptotic cell death process in the prostate is known to be under the control of androgens. Tumor necrosis factor-alpha (TNF-alpha)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF-alpha family of cytokines, known to induce apoptosis upon binding to its death domain-containing receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2. Two additional TRAIL receptors, DcR1/TRAIL-R3 and DcR2/TRAIL-R4, lack functional death domains and act as decoy receptors for TRAIL. In this study, we examined whether TRAIL and cellular receptors expression was targeted by androgens during the apoptotic cell death process in the hormone sensitive ventral prostate. The role of androgens was investigated using two sets of experiment. (1) Androgen deprivation associated with an apoptotic process resulted in a decrease in DcR2 mRNA and protein expression in the ventral prostate 3 days after castration. Testosterone administration to castrated adult rats prevented the decrease in DcR2 mRNA and protein levels in the ventral prostate. In contrast, DcR2 expression was modified, neither in the dorsolateral nor in the anterior prostate following castration. No changes were observed in DR4, DR5, DcR1, and TRAIL mRNA and protein levels in prostate after castration. (2) A specific decrease in DcR2 expression was observed in the ventral prostate after treatment of rats with the anti-androgen flutamide. Together, the present results suggest that testosterone specifically controls DcR2 expression in the adult rat ventral prostate. Androgen withdrawal, by reducing DcR2 expression, might leave the cells vulnerable to cell death signals generated by TRAIL via its functional receptors.
Assuntos
Androgênios/farmacologia , Proteínas Reguladoras de Apoptose/metabolismo , Glicoproteínas de Membrana/metabolismo , Próstata/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Antagonistas de Androgênios/farmacologia , Animais , Apoptose , Proteínas Reguladoras de Apoptose/fisiologia , Castração , Flutamida/farmacologia , Células HeLa , Humanos , Masculino , Glicoproteínas de Membrana/fisiologia , Próstata/citologia , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores do Fator de Necrose Tumoral/genética , Reprodutibilidade dos Testes , Ligante Indutor de Apoptose Relacionado a TNF , Testosterona/farmacologia , Fator de Necrose Tumoral alfa/fisiologiaRESUMO
Tumour necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) is a member of the tumour necrosis factor-alpha (TNF-alpha) family of cytokines which is known to induce apoptosis upon binding to its death domain-containing receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2. Two additional TRAIL receptors, DcR1/TRAIL-R3 and DcR2/TRAIL-R4, lack functional death domains and act as decoy receptors for TRAIL. In this study, the presence of TRAIL and its receptors was investigated by immunohistochemistry in adult human testes. In addition, TRAIL and its receptors were studied in terms of protein and mRNA using western blot analysis and RT-PCR respectively. TRAIL and its receptors were immunodetected according to the different testicular cell types: TRAIL, DR5/TRAIL-R2 and DcR2/TRAIL-R4 were localized in Leydig cells, DR4/TRAIL-R1 was seen in peritubular and Sertoli cells whereas ligand and all receptors were detected in germ cells. Proteins and mRNA corresponding to TRAIL and its receptors were also identified in adult human testes. In conclusion, TRAIL and its receptors DR4/TRAIL-R1, DR5/TRAIL-R2, DcR1/TRAIL-R3 and DcR2/TRAIL-R4 are expressed in the human testis, and are predominantly localized in different germ cell types.
Assuntos
Glicoproteínas de Membrana/análise , Receptores do Fator de Necrose Tumoral/análise , Testículo/química , Fator de Necrose Tumoral alfa/análise , Adulto , Idoso , Apoptose/fisiologia , Proteínas Reguladoras de Apoptose , Proteínas Ligadas por GPI , Células HeLa , Humanos , Imunoquímica , Células Intersticiais do Testículo/química , Células Intersticiais do Testículo/citologia , Masculino , Glicoproteínas de Membrana/genética , Proteínas de Membrana/análise , Pessoa de Meia-Idade , RNA Mensageiro/química , Receptores do Ligante Indutor de Apoptose Relacionado a TNF , Receptores do Fator de Necrose Tumoral/genética , Membro 10c de Receptores do Fator de Necrose Tumoral , Células de Sertoli/química , Células de Sertoli/citologia , Espermátides/química , Espermátides/citologia , Espermatócitos/química , Espermatócitos/citologia , Ligante Indutor de Apoptose Relacionado a TNF , Testículo/citologia , Receptores Chamariz do Fator de Necrose Tumoral , Fator de Necrose Tumoral alfa/genéticaRESUMO
Tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor-alpha family of cytokines that is known to induce apoptosis upon binding to its death domain-containing receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2. Two additional TRAIL receptors, DcR1/TRAIL-R3 and DcR2/TRAIL-R4, lack functional death domains and act as decoy receptors for TRAIL. In this study, the presence of TRAIL and its receptors was investigated in the rat testis during development. TRAIL and its receptors were immunolocalized to the different testicular cell types. TRAIL and its receptors were also identified in the rat testis in terms of protein and mRNA. Our immunohistochemical studies indicate that TRAIL, DR5/TRAIL-R2, and DcR2-TRAIL-R4 are detected in Leydig cells, whereas ligand and all receptors are localized in germ cells. TRAIL was permanently immunodetected in germ cells from the fetal stage to adulthood, whereas its receptors were immunolocalized exclusively in postmeiotic germ cells. The expression of TRAIL and receptor mRNAs was consistent with the immunodetection of TRAIL and receptor proteins. Indeed, TRAIL ligand mRNA was also identified in the rat testis from the fetal stage to adulthood. The mRNAs of the death receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2, were weakly detected during the perinatal period and increased from the pubertal stage to adulthood. The mRNAs of the decoy receptors, DcR1 and DcR2, were present in the rat testis at all ages studied, but the DcR2/TRAIL-R4 mRNa level was higher from the pubertal period to adulthood. Together, the present findings demonstrate that 1) TRAIL and its receptors are expressed in the testis during normal development, and 2) TRAIL protein is present in the different germ cell types, whereas its receptors were predominantly detected in the postmeiotic germ cells.
Assuntos
Expressão Gênica , Testículo/crescimento & desenvolvimento , Testículo/metabolismo , Envelhecimento , Animais , Proteínas Ligadas por GPI , Imuno-Histoquímica , Masculino , Ratos , Ratos Sprague-Dawley , Receptores do Ligante Indutor de Apoptose Relacionado a TNF , Receptores do Fator de Necrose Tumoral/análise , Receptores do Fator de Necrose Tumoral/genética , Membro 10c de Receptores do Fator de Necrose Tumoral , Maturidade Sexual , Espermatozoides/química , Testículo/química , Receptores Chamariz do Fator de Necrose TumoralRESUMO
Tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor-alpha (TNF-alpha) family of cytokines that is known to induce apoptosis upon binding to its death domain-containing receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2. Two additional TRAIL receptors, DcR1/TRAIL-R3 and DcR2/TRAIL-R4, lack functional death domains and act as decoy receptors for TRAIL. In this study, the presence of TRAIL and its receptors was investigated in adult rat hormonosensitive ventral prostate. TRAIL and its receptors were identified in the rat ventral prostate in terms of protein and mRNA. TRAIL and its receptors were immunolocalized in prostatic epithelial cells.
