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1.
Front Neurosci ; 16: 882559, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35812222

RESUMO

The quest for neuroprotective factors that can prevent or slow down the progression of retinal degeneration is still ongoing. Acute hypoxic stress has been shown to provide transient protection against subsequent damage in the retina. Stanniocalcins - STC1 and STC2 - are secreted glycoproteins that are hypoxia-regulated and were shown to be cytoprotective in various in vitro studies. Hence, we investigated the expression of stanniocalcins in the normal, degenerating and hypoxic retina. We show that the expression of Stc1 and Stc2 in the retina was detectable as early as postnatal day 10 and persisted during aging. Retinal expression of Stc2, but not Stc1, was induced in mice in an in vivo model of acute hypoxia and a genetic model of chronic hypoxia. Furthermore, we show that HIF1, not HIF2, is responsible for regulating Stc2 in cells with the molecular response to hypoxia activated due to the absence of von Hippel Lindau protein. Surprisingly, Stc2 was not normally expressed in photoreceptors but in the inner retina, as shown by laser capture microdissection and immunofluorescence data. The expression of both Stc1 and Stc2 remained unchanged in the degenerative retina with an almost complete loss of photoreceptors, confirming their expression in the inner retina. However, the absence of either Stc1 or Stc2 had no effect on retinal architecture, as was evident from retinal morphology of the respective knockout mice. Taken together our data provides evidence for the differential regulation of STC1 and STC2 in the retina and the prospect of investigating STC2 as a retinal neuroprotective factor.

2.
Clin Exp Metastasis ; 32(1): 15-27, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25391215

RESUMO

Stanniocalcin-1 (STC1) is a secreted glycoprotein implicated in several pathologies including retinal degeneration, cerebral ischemia, angiogenesis and inflammation. Aberrant STC1 expression has been reported in breast cancer but the significance of this is not clear. High levels of STC1 expression were found in the aggressive 4T1 murine mammary tumor cells and in the MDA-MB-231 human breast cancer line. To investigate its significance, stable clones with STC1 down-regulation using shRNA were generated in both tumor models. The consequences of STC1 down-regulation on cell proliferation, chemotactic invasion, tumor growth and metastasis were assessed. Down-regulation of STC1 in the 4T1 murine mammary tumor cells had a major impact on mammary tumor growth. This observation was replicated in a second tumor model with the MDA-MB-231 human breast cancer line, with a significant reduction in primary tumor formation and a major inhibition of metastasis as well. Interestingly, in both models, proliferation in vitro was not affected. Subsequent microarray gene expression profiling identified 30 genes to be significantly altered by STC1 down-regulation, the majority of which are associated with known hallmarks of carcinogenesis. Furthermore, bioinformatic analysis of breast cancer datasets revealed that high expression of STC1 is associated with poor survival. This is the first study to show definitively that STC1 plays an oncogenic role in breast cancer, and indicates that STC1 could be a potential therapeutic target for treatment of breast cancer patients.


Assuntos
Neoplasias Ósseas/secundário , Neoplasias da Mama/patologia , Glicoproteínas/biossíntese , Neoplasias Hepáticas/secundário , Neoplasias Pulmonares/secundário , Animais , Linhagem Celular Tumoral , Proliferação de Células , Regulação para Baixo , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Glicoproteínas/genética , Humanos , Metástase Linfática , Camundongos , Camundongos Endogâmicos BALB C , Camundongos SCID , Invasividade Neoplásica/genética , Interferência de RNA , RNA Interferente Pequeno
3.
Cancer Res ; 73(4): 1287-97, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-23243022

RESUMO

Platelet-derived growth factor (PDGF) receptor signaling is a major functional determinant of cancer-associated fibroblasts (CAF). Elevated expression of PDGF receptors on stromal CAFs is associated with metastasis and poor prognosis, but mechanism(s) that underlie these connections are not understood. Here, we report the identification of the secreted glycoprotein stanniocalcin-1 (STC1) as a mediator of metastasis by PDGF receptor function in the setting of colorectal cancer. PDGF-stimulated fibroblasts increased migration and invasion of cocultured colorectal cancer cells in an STC1-dependent manner. Analyses of human colorectal cancers revealed significant associations between stromal PDGF receptor and STC1 expression. In an orthotopic mouse model of colorectal cancer, tumors formed in the presence of STC1-deficient fibroblasts displayed reduced intravasation of tumor cells along with fewer and smaller distant metastases formed. Our results reveal a mechanistic basis for understanding the contribution of PDGF-activated CAFs to cancer metastasis.


Assuntos
Neoplasias Colorretais/metabolismo , Fibroblastos/metabolismo , Glicoproteínas/metabolismo , Receptores do Fator de Crescimento Derivado de Plaquetas/metabolismo , Animais , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Fibroblastos/efeitos dos fármacos , Perfilação da Expressão Gênica , Glicoproteínas/genética , Células HCT116 , Células HT29 , Humanos , Imuno-Histoquímica , Hibridização In Situ , Camundongos , Camundongos Knockout , Invasividade Neoplásica , Neoplasias Experimentais/genética , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Análise de Sequência com Séries de Oligonucleotídeos , Fator de Crescimento Derivado de Plaquetas/farmacologia , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transplante Heterólogo
4.
PLoS One ; 6(2): e17036, 2011 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-21347226

RESUMO

Approximately 10% of cancers use recombination-mediated Alternative Lengthening of Telomeres (ALT) instead of telomerase to prevent telomere shortening. A characteristic of cells that utilize ALT is the presence of ALT-associated PML nuclear bodies (APBs) containing (TTAGGG)n DNA, telomere binding proteins, DNA recombination proteins, and heterochromatin protein 1 (HP1). The function of APBs is unknown and it is possible that they are functionally heterogeneous. Most ALT cells lack functional p53, and restoration of the p53/p21 pathway in these cells results in growth arrest/senescence and a substantial increase in the number of large APBs that is dependent on two HP1 isoforms, HP1α and HP1γ. Here we investigated the mechanism of HP1-mediated APB formation, and found that histone chaperones, HIRA and ASF1a, are present in APBs following activation of the p53/p21 pathway in ALT cells. HIRA and ASF1a were also found to colocalize inside PML bodies in normal fibroblasts approaching senescence, providing evidence for the existence of a senescence-associated ASF1a/HIRA complex inside PML bodies, consistent with a role for these proteins in induction of senescence in both normal and ALT cells. Moreover, knockdown of HIRA but not ASF1a significantly reduced p53-mediated induction of large APBs, with a concomitant reduction of large HP1 foci. We conclude that HIRA, in addition to its physical and functional association with ASF1a, plays a unique, ASF1a-independent role, which is required for the localization of HP1 to PML bodies and thus for APB formation.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Núcleo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Chaperonas de Histonas/metabolismo , Homeostase do Telômero , Fatores de Transcrição/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Proteínas de Ciclo Celular/deficiência , Proteínas de Ciclo Celular/genética , Nucléolo Celular/metabolismo , Senescência Celular , Homólogo 5 da Proteína Cromobox , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Técnicas de Silenciamento de Genes , Células HeLa , Chaperonas de Histonas/deficiência , Chaperonas de Histonas/genética , Humanos , Chaperonas Moleculares , Fatores de Transcrição/deficiência , Fatores de Transcrição/genética , Proteína Supressora de Tumor p53/metabolismo
5.
Cancer Res ; 68(9): 3115-23, 2008 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-18451136

RESUMO

Activation of telomerase is a crucial step during cellular immortalization, and in some tumors this results from amplification of the human telomerase reverse transcriptase (hTERT) gene. Immortalization of normal human cells has been achieved by transduction with hTERT cDNA under the control of a strong heterologous enhancer/promoter, but this is sometimes an inefficient process, with periods of poor growth or even crisis occurring before immortalization. Here, we showed that normal human mammary epithelial cells expressing exogenous hTERT amplified the transgene extensively and expressed high levels of hTERT mRNA and protein. Paradoxically, the cells had low levels of telomerase activity and very short telomeres, indicating that telomerase activity did not correlate with hTERT expression. These cells contained only approximately 20 human telomerase RNA (hTR) molecules/cell (compared with approximately 120 hTR molecules per 293 cell). Expression of exogenous hTR caused increased telomerase activity and telomere lengthening. These data indicate that some hTERT-transduced normal cells may express high levels of the transgene but fail to up-regulate endogenous hTR expression sufficiently to enable expression of robust levels of telomerase activity.


Assuntos
Amplificação de Genes , Glândulas Mamárias Humanas/metabolismo , RNA Mensageiro/metabolismo , Telomerase/genética , Telomerase/metabolismo , Linhagem Celular Transformada , Dosagem de Genes/fisiologia , Regulação da Expressão Gênica , Humanos , Telômero/metabolismo , Transfecção
6.
Endocrinology ; 149(5): 2403-10, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18258678

RESUMO

Stanniocalcin (STC), a secreted glycoprotein, was first studied in fish as a classical hormone with a role in regulating serum calcium levels. There are two closely related proteins in mammals, STC1 and STC2, with functions that are currently unclear. Both proteins are expressed in numerous mammalian tissues rather than being secreted from a specific endocrine gland. No phenotype has been detected yet in Stc1-null mice, and to investigate whether Stc2 could have compensated for the loss of Stc1, we have now generated Stc2(-/-) and Stc1(-/-) Stc2(-/-) mice. Although Stc1 is expressed in the ovary and lactating mouse mammary glands, like the Stc1(-/-) mice, the Stc1(-/-) Stc2(-/-) mice had no detected decrease in fertility, fecundity, or weight gain up until weaning. Serum calcium and phosphate levels were normal in Stc1(-/-) Stc2(-/-) mice, indicating it is unlikely that the mammalian stanniocalcins have a major physiological role in mineral homeostasis. Mice with Stc2 deleted were 10-15% larger and grew at a faster rate than wild-type mice from 4 wk onward, and the Stc1(-/-) Stc2(-/-) mice had a similar growth phenotype. This effect was not mediated through the GH/IGF-I axis. The results are consistent with STC2 being a negative regulator of postnatal growth.


Assuntos
Glicoproteínas/fisiologia , Crescimento e Desenvolvimento/genética , Animais , Animais Recém-Nascidos , Peso Corporal/genética , Desenvolvimento Ósseo/genética , Cruzamentos Genéticos , Feminino , Glicoproteínas/genética , Peptídeos e Proteínas de Sinalização Intercelular , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Atividade Motora/genética , Músculo Esquelético/fisiologia , Tamanho do Órgão/genética , Reprodução/genética , Caracteres Sexuais
7.
Mol Cell Biol ; 25(23): 10604-10, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16287871

RESUMO

The stanniocalcin 1 (STC1) gene is expressed in a wide variety of tissues, including the kidney, prostate, thyroid, bone, and ovary. STC1 protein is considered to have roles in many physiological processes, including bone development, reproduction, wound healing, angiogenesis, and modulation of inflammatory response. In fish, STC1 is a hormone that is secreted by the corpuscles of Stannius and is involved in calcium and phosphate homeostasis. To determine the role of STC1 in mammals, we generated Stc1-null mice by gene targeting. The number of Stc1-/- mice obtained was in accordance with Mendelian ratios, and both males and females produced offspring normally. No anatomical or histological abnormalities were detected in any tissues. Our results demonstrated that Stc1 function is not essential for growth or reproduction in the mouse.


Assuntos
Desenvolvimento Embrionário/fisiologia , Glicoproteínas/metabolismo , Reprodução/fisiologia , Animais , Western Blotting , Cálcio/sangue , Células Cultivadas , Colecalciferol/farmacologia , Desenvolvimento Embrionário/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Glicoproteínas/deficiência , Glicoproteínas/genética , Heterozigoto , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fósforo/sangue , Condicionamento Físico Animal , RNA Mensageiro/genética , Reprodução/genética
8.
Mol Cell Biol ; 25(7): 2708-21, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15767676

RESUMO

Approximately 10% of cancers overall use alternative lengthening of telomeres (ALT) instead of telomerase to prevent telomere shortening, and ALT is especially common in astrocytomas and various types of sarcomas. The hallmarks of ALT in telomerase-negative cancer cells include a unique pattern of telomere length heterogeneity, rapid changes in individual telomere lengths, and the presence of ALT-associated promyelocytic leukemia bodies (APBs) containing telomeric DNA and proteins involved in telomere binding, DNA replication, and recombination. The ALT mechanism appears to involve recombination-mediated DNA replication, but the molecular details are largely unknown. In telomerase-null Saccharomyces cerevisiae, an analogous survivor mechanism is dependent on the RAD50 gene. We demonstrate here that overexpression of Sp100, a constituent of promyelocytic leukemia nuclear bodies, sequestered the MRE11, RAD50, and NBS1 recombination proteins away from APBs. This resulted in repression of the ALT mechanism, as evidenced by progressive telomere shortening at 121 bp per population doubling, a rate within the range found in telomerase-negative normal cells, suppression of rapid telomere length changes, and suppression of APB formation. Spontaneously generated C-terminally truncated Sp100 that did not sequester the MRE11, RAD50, and NBS1 proteins failed to inhibit ALT. These findings identify for the first time proteins that are required for the ALT mechanism.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas Nucleares/metabolismo , Telômero/metabolismo , Linhagem Celular , Regulação da Expressão Gênica , Humanos , Mutação/genética , Proteínas Nucleares/genética , Ligação Proteica , RNA Interferente Pequeno , Telômero/genética , Transgenes/genética
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