RESUMO
Von Hippel-Lindau (VHL) disease results from the inactivation of the VHL gene and is characterized by highly vascular tumors. A consequence of VHL loss is the stabilization of hypoxia-inducible factor (HIF) alpha subunits and increased expression of HIF target genes, which include pro-angiogenic growth factors such as vascular endothelial growth factor (VEGF). In mice, homozygous deletion of VHL is embryonic lethal due to vascular abnormalities in the placenta; and, VHL(+/-) mice develop proliferative vascular lesions in several major organs, most prominently the liver. Loss of ELL-associated factor (EAF2) in murine models has also been shown to induce increased vascular density in the liver as well as the prostate. Previously, EAF2 was determined to be a binding partner of VHL and loss of EAF2 induced a reduction in pVHL levels and an increase in hypoxia induced factor 1α (HIF1α) levels in vitro. Here we characterized the cooperative effects of VHL- and EAF2-deficiency on angiogenesis in the liver and prostate of male mice. VHL deficiency consistently increased the incidence of hepatic vascular lesions across three mouse strains. These vascular lesions where characterized by an increase in microvessel density, and staining intensity of VHL target proteins HIF1α and VEGF. EAF2(-/-)VHL(+/-) mice had increased incidence of proliferative hepatic vascular lesions (4/4) compared to VHL(+/-) (10/18) and EAF2(-/-) (0/5) mice. Prostates of EAF2(-/-)VHL(+/-) mice also displayed an increase in microvessel density, as well as stromal inflammation and prostatic intraepithelial neoplasia. These results suggest that cooperation of VHL and EAF2 may be critical for angiogenic regulation of the liver and prostate, and concurrent loss of these two tumor suppressors may result in a pro-angiogenic phenotype.
Assuntos
Heterozigoto , Fígado/metabolismo , Neovascularização Patológica/metabolismo , Proteínas Nucleares/metabolismo , Próstata/metabolismo , Transativadores/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismo , Doença de von Hippel-Lindau/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Fígado/patologia , Masculino , Camundongos , Camundongos Knockout , Neovascularização Patológica/genética , Neovascularização Patológica/patologia , Proteínas Nucleares/genética , Próstata/patologia , Neoplasia Prostática Intraepitelial/genética , Neoplasia Prostática Intraepitelial/metabolismo , Neoplasia Prostática Intraepitelial/patologia , Transativadores/genética , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Doença de von Hippel-Lindau/genética , Doença de von Hippel-Lindau/patologiaRESUMO
Von Hippel-Lindau (VHL) disease type 2A is an inherited tumor syndrome characterized by predisposition to pheochromocytoma (pheo), retinal hemangioma (RA), and central nervous system hemangioblastoma (HB). Specific VHL subtypes display genotype-phenotype correlations but, unlike other familial syndromes such as MEN-2, the phenotype in VHL has not yet been stratified at the codon level. Over decades, we have managed two very large VHL type 2A regional kindreds with nearly adjacent but distinct VHL missense mutations. We determined the phenotype of Family 2 and compared the clinical and pathologic parameters of pheo between 30 members of Family 1 (Y112H mutation) and 33 members of Family 2 (Y98H mutation) with mean follow-up of 15.5 and 12.1 years, respectively (P = 0.24). In Family 2, pheo was the most frequent VHL manifestation (79%) and all pheo diagnoses occurred by age 50. Age at first diagnosis was younger in Family 2 than in Family 1 (mean 19.7 vs. 28.8 years; P = 0.02). Pheo expressivity differed by genotype: Family 1 pheo was more likely to be multifocal (P = 0.04), as well as malignant (P < 0.01) and lethal (P = 0.02). Family 1 pheo was also more likely to secrete vanillylmandelic acid (VMA) alone (P = 0.05). This analysis of 130 pheochromocytomas in 63 VHL type 2A patients demonstrates that mutation-specific malignancy and expression patterns exist within the VHL type 2A subtype, and provides information that may help tailor the screening and management algorithms of affected members and those at risk.
Assuntos
Neoplasias das Glândulas Suprarrenais/genética , Mutação de Sentido Incorreto/genética , Fenótipo , Feocromocitoma/genética , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Doença de von Hippel-Lindau/genética , Fatores Etários , Família , Feminino , Genótipo , Humanos , Imageamento por Ressonância Magnética , Masculino , Linhagem , Penetrância , Análise de SobrevidaRESUMO
The FHIT gene plays important roles in cancer development, including lung cancers, in which the Fhit protein is frequently lost. To determine if Fhit-deficient mice exhibit increased susceptibility to carcinogen-induced lung cancer, mice were treated with the pulmonary carcinogen 4-methylnitrosamino-1-3-pyridyl-1-butanone. Wild-type and Fhit-deficient animals did not exhibit significantly different frequencies of lung lesions, but Fhit-/- mice showed significantly increased average tumor volume (1.62 mm3) and multiplicity in tumor-bearing mice, compared with wild-type mice (0.70 mm3). Tumors of Fhit-/- mice were all carcinomas, whereas Fhit+/+ mice did not develop carcinomas. To determine if Fhit absence, in combination with deficiency of an additional 3p tumor suppressor, would affect the frequency of tumor induction, we examined the spontaneous and dimethylnitrosamine-induced tumor phenotype of Fhit-/-Vhl+/- mice. Whereas no spontaneous lung tumors were observed in Fhit-/- or Vhl+/- mice, 44% of Fhit-/-Vhl+/- mice developed adenocarcinomas by 2 years of age. Dimethylnitrosamine (6 mg/kg body weight) induced lung tumors (adenomas and carcinomas) in 100% of Fhit-/-Vhl+/- mice and adenomas in 40% of Fhit-/- mice by 20 months of age. Thus, double deficiency in murine homologues of 3p suppressor genes, including haploinsufficiency of Vhl, predisposes to spontaneous and induced lung cancers, showing that Fhit-deficient mice will be useful, in combination with other 3p tumor suppressors, in recapitulating a pattern of lung cancer development similar to the human pattern; such double- or triple-deficient mice will be excellent lung cancer prevention and therapy models.
Assuntos
Hidrolases Anidrido Ácido/deficiência , Cocarcinogênese , Neoplasias Pulmonares/genética , Proteínas de Neoplasias/deficiência , Proteínas Supressoras de Tumor/deficiência , Ubiquitina-Proteína Ligases/deficiência , Hidrolases Anidrido Ácido/genética , Alelos , Animais , Carcinógenos , Feminino , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Predisposição Genética para Doença , Haploidia , Neoplasias Pulmonares/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas de Neoplasias/genética , Nitrosaminas , Proteínas Supressoras de Tumor/genética , Ubiquitina-Proteína Ligases/genética , Proteína Supressora de Tumor Von Hippel-LindauRESUMO
The blood clotting cascade is selectively involved in lung metastasis, but the reason for this selectivity is unclear. Here, we show that tumor cells that metastasize predominantly to the lung, such as renal cell carcinoma (RCC) and soft tissue sarcoma (STS), have an inherent capacity to generate extensive invadopodia when embedded in a blood clot. Compared with other metastatic cancer cells tested, RCC and STS cells exhibited increased levels of expression of fibronectin and an activated form of the integrin αvß3, which coordinately supported the generation of an elaborate fibronectin matrix and actin stress fibers in fibrin-embedded tumor cells. Together, fibronectin and αvß3 induced upregulation of the transcription factor Slug, which mediates epithelial-mesenchymal transition as well as fibrin invasion and lung metastasis. This mechanism is clinically significant, because primary cancer cells from patients with metastatic RCC strongly invaded fibrin and this correlated with fibronectin matrix formation and Slug expression. In contrast, tumor cells from patients with localized RCC were largely noninvasive. Together, our findings establish that activated integrin αvß3 and fibronectin promote lung metastasis by upregulating Slug, defining a mechanism through which cancer cells can colonize blood clots in the lung vasculature.
Assuntos
Fibronectinas/metabolismo , Integrina alfaVbeta3/metabolismo , Neoplasias/sangue , Neoplasias/patologia , Fatores de Transcrição/metabolismo , Animais , Adesão Celular , Linhagem Celular Tumoral , Feminino , Fibronectinas/genética , Inativação Gênica , Humanos , Integrina alfaVbeta3/genética , Masculino , Camundongos Nus , Microscopia Confocal , Invasividade Neoplásica , Metástase Neoplásica , Neoplasias/metabolismo , Fatores de Transcrição da Família Snail , Trombose/patologia , Fatores de Transcrição/genética , Regulação para CimaRESUMO
The von Hippel-Lindau (VHL) tumor suppressor gene product is the recognition component of an E3 ubiquitin ligase and is inactivated in patients with VHL disease and in most sporadic clear-cell renal cell carcinomas (RCC). pVHL controls oxygen-responsive gene expression at the transcriptional and posttranscriptional levels. The VEGFA mRNA contains AU-rich elements (ARE) in the 3'-untranslated region, and mRNA stability or decay is determined through ARE-associated RNA-binding factors. We show here that levels of the ARE-binding factor, AUF1, are regulated by pVHL and by hypoxia. pVHL and AUF1 stably associate with each other in cells and AUF1 is a ubiquitylation target of pVHL. AUF1 and another RNA-binding protein, HuR, bind to VEGFA ARE RNA. Ribonucleoprotein (RNP) immunoprecipitations showed that pVHL associates indirectly with VEGFA mRNA through AUF1 and/or HuR, and this complex is associated with VEGFA mRNA decay under normoxic conditions. Under hypoxic conditions pVHL is downregulated, whereas AUF1 and HuR binding to VEGF mRNA is maintained, and this complex is associated with stabilized mRNA. These studies suggest that AUF1 and HuR bind to VEGFA ARE RNA under both normoxic and hypoxic conditions, and that a pVHL-RNP complex determines VEGFA mRNA decay. These studies further implicate the ubiquitin-proteasome system in ARE-mediated RNA degradation.
Assuntos
Ribonucleoproteínas Nucleares Heterogêneas Grupo D/metabolismo , Processamento Pós-Transcricional do RNA , RNA Mensageiro/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismo , Hipóxia Celular/genética , Hipóxia Celular/fisiologia , Células Cultivadas , Proteínas ELAV/genética , Proteínas ELAV/metabolismo , Proteínas ELAV/fisiologia , Células HEK293 , Ribonucleoproteína Nuclear Heterogênea D0 , Ribonucleoproteínas Nucleares Heterogêneas Grupo D/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo D/fisiologia , Humanos , Modelos Biológicos , Ligação Proteica/fisiologia , Processamento Pós-Transcricional do RNA/genética , Estabilidade de RNA/genética , Sequências Reguladoras de Ácido Ribonucleico/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Proteína Supressora de Tumor Von Hippel-Lindau/fisiologiaRESUMO
PURPOSE: We evaluated the effects of the over expression of p27Kip1, a cyclin dependent kinase inhibitor and tumor suppressor protein, on the 786-0 human renal carcinoma cell line. MATERIALS AND METHODS: The recombinant adenovirus Adp27Kip1 was evaluated for the induction of p27 protein expression in 786-0 renal carcinoma cells. Expression time and optimal vector concentration were determined. Growth curve studies, cell cycle analysis and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling were done to determine the effects of p27Kip1 on the cell cycle. Cyclin dependent protein kinase (Cdk) inhibitor (CDKI) activity assays were done to determine the expression/activities of Cdks and Western blot analysis was performed to determine the presence of CDKIs and other cell cycle regulator proteins. Nude mouse xenografts were established to demonstrate the in vivo efficacy of Adp27Kip1. RESULTS: p27Kip1 protein expression was detected within 12 hours after Adp27Kip1 infection and it remained stable for at least 48 hours. Growth studies demonstrated that Adp27Kip1 infection resulted in the inhibition of proliferation by 3 days after infection and cell death was detected by day 5. Cell cycle analysis of DNA content indicated an accumulation of cells in the G1 phase of Adp27Kip1 infected cells and a corresponding decrease in S phase cells within 48 hours after infection. Cdk activity was determined, and Cdk2, Cdk4 and Cdc2 kinase activities were inhibited, consistent with p27Kip1 over expression. The levels of the CDKIs p16 and p18 were elevated 24 hours after Adp27Kip1 infection, while p21 levels remained unchanged. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling revealed that Adp27Kip1 infection but not infection by control virus induced detectable apoptosis within 24 hours. Adp27Kip1 significantly caused the reduction in the size of tumors of the renal cell carcinoma xenografts. CONCLUSIONS: This study demonstrates the potential effectiveness of Adp27Kip1 as a vector for gene therapy studies of renal cell carcinoma.
Assuntos
Adenoviridae/genética , Apoptose/genética , Carcinoma de Células Renais/patologia , Proteínas de Ciclo Celular/genética , Ciclo Celular/genética , Divisão Celular/genética , Terapia Genética , Vetores Genéticos/genética , Neoplasias Renais/patologia , Recombinação Genética/genética , Células Tumorais Cultivadas/patologia , Proteínas Supressoras de Tumor/genética , Animais , Inibidor de Quinase Dependente de Ciclina p27 , Feminino , Regulação Neoplásica da Expressão Gênica/fisiologia , Regulação Viral da Expressão Gênica/fisiologia , Humanos , Marcação In Situ das Extremidades Cortadas , Camundongos , Camundongos Nus , Transplante de NeoplasiasRESUMO
The von Hippel-Lindau (VHL) tumor suppressor gene plays a prominent role in the development of renal cell carcinoma (RCC) in humans. VHL functions as a ubiquitin E3 ligase, controlling the stability of hypoxia inducible factor (HIF) and tumor angiogenesis. Alterations in this tumor suppressor gene are rarely observed in spontaneous or chemically induced RCC that arise in conventional strains of rodents and Vhl knockout mice (Vhl+/-) do not develop spontaneous RCC. We tested whether Vhl knockout mice exhibited increased susceptibility to renal carcinogenesis using the well-characterized renal carcinogen streptozotocin. No differences were observed between wild-type and Vhl+/- animals in the frequency or type of renal lesions induced by 50-200 mg/kg streptozotocin. Carcinogen-induced RCC that developed in Vhl heterozygotes and wild-type mice did not contain mutations in the wild-type Vhl, as determined by direct sequencing of the primary tumors. While Vhl+/- mice exhibited no increase in renal lesions in response to streptozotocin, heterozygous animals did develop vascular proliferative lesions of the liver, uterus, ovary, spleen and heart. These lesions, ranging from angiectasis to hemangiosarcoma, were most prominent in the livers of Vhl+/- mice, where they were found in high incidence and high multiplicity. Wild-type mice developed a low-frequency of liver angiectasis (7-15%) only at the highest doses of carcinogen used (150 and 200 mg/kg, respectively) while Vhl+/- mice exhibited angiectasis, hemangioma and hemangiosarcomas with a frequency ranging from 19 to 46% at 50-200 mg/kg streptozotocin. Untreated Vhl+/- mice had a spontaneous incidence of hepatic vascular lesions of 21%. Furthermore, vascular lesions of the uterus, ovary, spleen and heart were observed only in Vhl+/- mice, with an incidence of (5-28%). Taken together, the data indicate that heterozygosity at the Vhl locus predisposes mice to a vascular phenotype ranging from angiectasis to hemangiosarcoma, consistent with the ability of this tumor suppressor gene to control the stability of HIF and regulate key proteins that participate in angiogenesis.