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Rac1 protects epithelial cells against anoikis
S J Coniglio1, T S Jou, M Symons
1Picower Institute for Medical Research, Manhasset, New York 11030, USA.
The Journal of Biological Chemistry
|May 23, 2001
Summary
Constitutive activation of Rac1, a Rho family protein, prevents anoikis (apoptosis from anchorage loss) in epithelial cells. This Rac1 signaling is crucial for cell survival during anchorage-independent growth, a hallmark of cancer.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Rho family proteins are critical in malignant transformation.
- Anchorage-independent growth and anoikis resistance are key features of transformed cells.
Purpose of the Study:
- To investigate the role of Rac1 in anoikis.
- To identify signaling pathways mediating Rac1-induced cell survival.
Main Methods:
- Used Madin-Darby canine kidney (MDCK) epithelial cells.
- Expressed constitutively active Rac1-V12 in suspended MDCK cells.
- Assessed DNA fragmentation, caspase activity, and cell survival.
- Utilized chemical and protein inhibitors to probe signaling pathways (ERK, p38, Akt, NF-kappaB).
Main Results:
- Constitutively active Rac1-V12 significantly decreased DNA fragmentation and caspase activity.
- Rac1-V12 expression increased cell survival in suspension.
- Rac1-mediated survival was dependent on phosphatidylinositol 3-kinase (PI3K) activity.
- ERK, p38, and NF-kappaB pathways were dispensable for Rac1-induced survival.
Conclusions:
- Rac1 activation suppresses apoptosis in epithelial cells under anchorage-independent conditions.
- Rac1-mediated survival signaling may play a role in cellular transformation and cancer development.