Molecular Cell
Volume 42, Issue 1, 8 April 2011, Pages 23-35
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Article
Oncogenic Ras-Induced Expression of Noxa and Beclin-1 Promotes Autophagic Cell Death and Limits Clonogenic Survival

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Summary

Deregulated oncogenes such as MYC and RAS are typically insufficient to transform cells on their own due to the activation of pathways that restrain proliferation. Previous studies have shown that oncogenic H-Ras can induce proliferative arrest or senescence, depending on the cellular context. Here, we show that deregulated H-Ras activity can also lead to caspase-independent cell death with features of autophagy. Ras-induced autophagy was associated with upregulation of the BH3-only protein Noxa as well as the autophagy regulator Beclin-1. Silencing of Noxa or Beclin-1 expression reduced Ras-induced autophagy and increased clonogenic survival. Ras-induced cell death was also inhibited by coexpression of Bcl-2 family members that inhibit Beclin-1 function. Ras-induced autophagy was associated with Noxa-mediated displacement of the Bcl-2 family member, Mcl-1, from Beclin-1. Thus, Ras-induced expression of Noxa and Beclin-1 promotes autophagic cell death, which represents a mechanism to limit the oncogenic potential of deregulated Ras signals.

Highlights

► Oncogenic H-RasV12 can promote cell death with features of autophagy ► H-RasV12 induced upregulation of the BH3-only protein, Noxa, as well as Beclin-1 ► Ras-induced Noxa displaced the Bcl-2 family member, Mcl-1, from Beclin-1 ► Autophagic cell death may limit the transforming potential of oncogenic forms of Ras

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Present address: Children's Cancer Centre, Murdoch Children's Research Institute, Flemington Road, Parkville, Victoria 3052, Australia