In:
American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 311, No. 2 ( 2016-08-01), p. G221-G236
Abstract:
Protease-activated receptors PAR 1 and PAR 2 play an important role in the control of epithelial cell proliferation and migration. However, the survival of normal and tumor intestinal stem/progenitor cells promoted by proinflammatory mediators may be critical in oncogenesis. The glycogen synthase kinase-3β (GSK3β) pathway is overactivated in colon cancer cells and promotes their survival and drug resistance. We thus aimed to determine PAR 1 and PAR 2 effects on normal and tumor intestinal stem/progenitor cells and whether they involved GSK3β. First, PAR 1 and PAR 2 were identified in colon stem/progenitor cells by immunofluorescence. In three-dimensional cultures of murine crypt units or single tumor Caco-2 cells, PAR 2 activation decreased numbers and size of normal or cancerous spheroids, and PAR 2 -deficient spheroids showed increased proliferation, indicating that PAR 2 represses proliferation. PAR 2 -stimulated normal cells were more resistant to stress (serum starvation or spheroid passaging), suggesting prosurvival effects of PAR 2 . Accordingly, active caspase-3 was strongly increased in PAR 2 -deficient normal spheroids. PAR 2 but not PAR 1 triggered GSK3β activation through serine-9 dephosphorylation in normal and tumor cells. The PAR 2 -triggered GSK3β activation implicates an arrestin/PP2A/GSK3β complex that is dependent on the Rho kinase activity. Loss of PAR 2 was associated with high levels of GSK3β nonactive form, strengthening the role of PAR 2 in GSK3β activation. GSK3 pharmacological inhibition impaired the survival of PAR 2 -stimulated spheroids and serum-starved cells. Altogether our data identify PAR 2 /GSK3β as a novel pathway that plays a critical role in the regulation of stem/progenitor cell survival and proliferation in normal colon crypts and colon cancer.
Type of Medium:
Online Resource
ISSN:
0193-1857
,
1522-1547
DOI:
10.1152/ajpgi.00328.2015
Language:
English
Publisher:
American Physiological Society
Publication Date:
2016
detail.hit.zdb_id:
1477329-6
SSG:
12
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