Author: Christina Holzer
Publisher:
ISBN:
Category :
Languages : en
Pages : 80

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Author: Benjamin G. Neel
Publisher: Springer
ISBN: 1493936492
Category : Medical
Languages : en
Pages : 362

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This book aims to bridge the gap in understanding how protein-tyrosine phosphatases (PTPs), which carry out the reverse reaction of tyrosine phosphorylation, feature in cancer cell biology. The expertly authored chapters will first review the general features of the PTP superfamily, including their overall structure and enzymological properties; use selected examples of individual PTP superfamily members, to illustrate emerging data on the role of PTPs in cancer; and will review the current status of PTP-based drug development efforts. Protein Tyrosine Phosphatases in Cancer,from renowned researchers Benjamin Neel and Nicholas Tonks, is invaluable reading for researchers in oncology, stem cell signaling,and biochemistry.

Author: Manfred Wirth
Publisher: Walter de Gruyter
ISBN: 3110807270
Category : Medical
Languages : en
Pages : 220

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Author: Nicola Aceto
Publisher:
ISBN:
Category :
Languages : en
Pages : 146

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Author: Yifan Zhai
Publisher:
ISBN:
Category : Breast
Languages : en
Pages : 296

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Author: Mairin Rafferty
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Sherry T. Shu
Publisher:
ISBN:
Category : Carcinogenesis
Languages : en
Pages : 154

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Abstract: Reduced expression of protein tyrosine phosphatase gamma (PTPG) has been shown in breast cancer cell lines and cancerous tissue. PTPG over-expression in breast cancer cell line MCF-7 leads to the inhibition of cell proliferation and anchorage- independent growth. To further investigate the anti-carcinogenic abilities of PTPG in vivo, athymic nude mice were implanted with MCF-7 cells, which were stably transfected with PTPG cDNA (M7-PTPG) or empty vectors (M7-PCR). Tumor formation was significantly lower at the M7-PTPG cells implanted sites (10%) compared to sites where M7-PCR cells were implanted (100%), indicating that tumor formation was inhibited by the effect of PTPG in vivo. To explore the signaling pathway that PTPG is involved, breast cancer-related signaling cDNA array assays were performed. Seventy genes showed at least a 1.5 fold of expression difference in M7-PTPG cells compared to M7- PCR cells. The increase of the levels of p21(cip) and p27(kip) in M7-PTPG cells was confirmed by Western blot analyses. M7-PTPG cells also showed delayed re-entry into the cell cycle after the cells were released from G0/G1 cell cycle arrest, accompanied by lower phosphorylation levels of ERK1/2, compared to the control cells. Moreover, there was an aberrant methylation pattern in the PTPG promoter region of the breast cancer cell lines and patient's cancerous tissue. PTPG expression in SkBr3 cells can be recovered by treating with deoxy-5-azacytidine (DAC) and trichostatin A (TSA). Our results indicate that PTPG inhibits breast tumor promotion in vivo, presumably through cell cycle arrest by the up-regulated p21(cip) and p27(kip) proteins; and DNA methylation is a possible mechanism that leads to PTPG silencing in breast cancer cells. The results obtained from this study suggest that PTPG plays important role in breast carcinogenesis and may serve as a breast cancer therapeutic target.

Author: Universitat de València. Facultat de Ciències Biològiques
Publisher:
ISBN:
Category :
Languages : en
Pages : 158

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 15

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Stromal-epithelial interactions regulate mammary epithelial cell (MEC) fate via integrin-growth factor receptor (GFR) interactions. Integrin-GFR crosstalk influences MEC behavior through activation of tyrosine kinase signaling that is tempered by protein tyrosine phosphatase (PTP) activity of which we know little about. Using a degenerate RT-PCR to amplify PTPs expressed in differentiated versus non-differentiated MECs, we identified the Band 4.1 PTPs MEG1 and Dl as two candidate PTP metastasis suppressors. Our studies show that during MEC differentiation PTP MEGl and Dl expression rise dramatically, coincident with assembly of E-cadherin/Beta-catenin adherens junction formation. However, both mRNA and protein expression of MEGl and Dl become repressed following MEC tissue differentiation. Because we could not establish any correlation between MEC growth, or tissue polarization, this suggests that MEG1 and Dl expression may be functionally linked to adherens junction assembly. Consistently, malignant MECs that fail to assemble adherens junctions do not modulate MEGl or Dl expression. Moreover, MEGl expression is not induced in phenotypically reverting tumors, or down regulated in dormant structures. This suggests that these Band 4.1 PTPs may be functionally-linked to molecules mediating adherens junction formation.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Tyrosine phosphorylation is controlled by a balance of tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Whereas the contribution of PTKs to breast tumorigenesis is the subject of intense scrutiny, the potential role of PTPs is poorly known. RPTP alpha is implicated in the activation of Src family kinases, and regulation of integrin signaling, cell adhesion, and growth factor responsiveness. To explore its potential contribution to human neoplasia, we surveyed RPTP alpha protein levels in primary human breast cancer. We found RPTPa levels to vary widely among tumors, with 29% of cases manifesting significant overexpression. High RPTP alpha protein levels correlated significantly with low tumor grade and positive estrogen receptor status. Expression of RPTPC alpha in breast carcinoma cells led to growth inhibition, associated with increased accumulation in G(0) and G(1), and delayed tumor growth and metastasis. To our knowledge, this is the first example of a study correlating expression level of a specific bona fide PTP with neoplastic disease status in humans.