RAS unplugged: negative feedback and oncogene-induced senescence.
Nabeel Bardeesy1, Norman E Sharpless
1Department of Medicine, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, Massachusetts 02114, USA. nelbardeesy@partners.org
Cancer Cell
|December 13, 2006
Summary
Oncogene activation triggers senescence, a tumor suppressor program. New findings reveal RAS/RAF pathway activation reduces MAPK and PI3K signaling, which is essential for this growth arrest.
Area of Science:
- Cellular biology
- Oncology
- Molecular signaling
Background:
- Senescence is a tumor suppressor mechanism where normal cells permanently arrest growth in response to stress like oncogene activation.
- Sustained activation of MAP kinase (MAPK) and PI3 kinase (PI3K) signaling was previously thought to drive oncogene-induced senescence.
Purpose of the Study:
- To investigate the signaling pathways involved in oncogene-induced senescence.
- To challenge the prevailing model of senescence induction.
Main Methods:
- Investigated the effects of aberrant RAS/RAF pathway activation on MAPK and PI3K signaling.
- Analyzed the role of signaling attenuation in senescence.
Main Results:
- Aberrant RAS/RAF pathway activation initiates a negative feedback loop.
- This feedback loop globally attenuates MAPK and PI3K signaling.
- Reduced MAPK and PI3K signaling is a prerequisite for senescence.
Conclusions:
- The established model of senescence induction via sustained MAPK/PI3K signaling is challenged.
- RAS/RAF pathway activation-mediated attenuation of MAPK/PI3K signaling is critical for senescence.
- Senescence is a complex process involving feedback mechanisms that regulate key signaling pathways.
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