Article

Beyond PTEN mutations: the PI3K pathway as an integrator of multiple inputs during tumorigenesis.

The Campbell Family Institute for Breast Cancer Research, University Health Network, University of Toronto, Toronto, Ontario M5G 2C1, Canada.
Nature reviews. Cancer (Impact Factor: 37.91). 04/2006; 6(3):184-92. DOI: 10.1038/nrc1819
Source: PubMed

ABSTRACT The tumour-suppressor phosphatase with tensin homology (PTEN) is the most important negative regulator of the cell-survival signalling pathway initiated by phosphatidylinositol 3-kinase (PI3K). Although PTEN is mutated or deleted in many tumours, deregulation of the PI3K-PTEN network also occurs through other mechanisms. Crosstalk between the PI3K pathways and other tumorigenic signalling pathways, such as those that involve Ras, p53, TOR (target of rapamycin) or DJ1, can contribute to this deregulation. How does the PI3K pathway integrate signals from numerous sources, and how can this information be used in the rational design of cancer therapies?

0 Bookmarks
 · 
126 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Hedgehog (Hh) signalling pathway plays a pivotal role in the spatial and temporal regulation of cell proliferation and differentiation. By controlling the correct maturation of developing tissues and ensuring attainment of the correct size, position and the presence of fully functioning cellular structures, the Hh plays a pivotal role in development. Conversely aberrant Hh signalling is involved in Gorlin syndrome, basal cell carcinoma (the most common cancer in the world), and more than one third of all human medulloblastoma cases. In all of these cases, it is believed that deregulated Hh signalling leads to increased cell proliferation and tumour formation. Inhibition of the Hedgehog signalling pathway, is a recently validated anti-cancer drug target, with vismodegib (Erivedge™), approved by the U.S. Food and Drug Administration for the treatment of adult basal cell carcinoma. In this perspective we outline the current state of Hh pathway inhibitors with a particular focus on potential limitations of upstream Hh pathway inhibition in relation to resistance mutations and crosstalk pathways. Together, these limitations indicate that inhibition of downstream components, specifically the Gli family of transcription factors, may represent a next generation approach to suppress tumours associated with aberrant Hh pathway signalling.
    Medicinal Chemistry Communication 01/2014; 5(2):117. DOI:10.1039/c3md00334e · 2.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: PTEN-Long is a translational variant of PTEN (Phosphatase and Tensin Homolog). Like PTEN, PTEN-Long is able to antagonize the PI3K-Akt pathway and inhibits tumor growth. In this study, we investigated the role PTEN-Long plays in the development and progression of clear cell renal cell carcinoma (ccRCC) and explored the therapeutic possibility using proteinaceous PTEN-Long to treat ccRCC. We found that the protein levels of PTEN-Long were drastically reduced in ccRCC, which was correlated with increased levels of phosphorylated Akt (pAkt). Gain of function experiments showed overexpression of PTEN-Long in the ccRCC cell line 786-0 suppressed PI3K-Akt signaling, inhibited cell proliferation, migration and invasion, and eventually induced cell death. When purified PTEN-Long was added into cultured 786-0 cells, it entered cells, blocked Akt activation, and induced apoptosis involving Caspase 3 cleavage. Furthermore, PTEN-Long inhibited proliferation of 786-0 cells in xenograft mouse model. Our results implicated that understanding the roles of PTEN-Long in renal cell carcinogenesis has therapeutic significance.
    PLoS ONE 01/2015; 10(2):e114250. DOI:10.1371/journal.pone.0114250 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Second heart field (SHF) progenitors exhibit continued proliferation and delayed differentiation, which are modulated by FGF4/8/10, BMP and canonical Wnt/β-catenin signaling. PTEN-Akt signaling regulates the stem cell/progenitor cell homeostasis in several systems, such as hematopoietic stem cells, intestinal stem cells and neural progenitor cells. To address whether PTEN-Akt signaling is involved in regulating cardiac progenitors, we deleted Pten in SHF progenitors. Deletion of Pten caused SHF expansion and increased the size of the SHF derivatives, the right ventricle and the outflow tract. Cell proliferation of cardiac progenitors was enhanced, whereas cardiac differentiation was unaffected by Pten deletion. Removal of Akt1 rescued the phenotype and early lethality of Pten deletion mice, suggesting that Akt1 was the key downstream target that was negatively regulated by PTEN in cardiac progenitors. Furthermore, we found that inhibition of FOXO by Akt1 suppressed the expression of the gene encoding the BMP ligand (BMP7), leading to dampened BMP signaling in the hearts of Pten deletion mice. Cardiac activation of Akt also increased the Ser552 phosphorylation of β-catenin, thus enhancing its activity. Reducing β-catenin levels could partially rescue heart defects of Pten deletion mice. We conclude that Akt signaling regulates the cell proliferation of SHF progenitors through coordination of BMP signaling and β-catenin activity. © 2015. Published by The Company of Biologists Ltd.

Preview

Download
14 Downloads
Available from