[Frontiers in Bioscience 16, 1693-1713, January 1, 2011]

Death pathways triggered by activated Ras in cancer cells

Jean H. Overmeyer, William A. Maltese

Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio 43614

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Overview of Ras Signaling
4. Induction of Apoptosis by Ras
5. Mechanisms of Ras-induced Apoptosis
5.1. Replication stress
5.2. The ERK pathway
5.3. The Rac pathway
5.4. The Bcl-2 proteins
6. Pro-Apoptotic Effects of Ras Mediated by the RASSF Family
7. Induction of Non-Apoptotic Cell Death by Ras
8. Mechanisms of Ras-Induced Non-Apoptotic Cell Death
8.1. Ras and autophagy
8.2. Ras and methuosis
9. Perspectives
10. Acknowledgements
11. References

1. ABSTRACT

Ras GTPases are best known for their ability to serve as molecular switches regulating cell growth, differentiation and survival. Gene mutations that result in expression of constitutively active forms of Ras have been linked to oncogenesis in animal models and humans. However, over the past two decades, evidence has gradually accumulated to support a paradoxical role for Ras proteins in the initiation of cell death pathways. In this review we survey the literature pointing to the ability of activated Ras to promote cell death under conditions where cancer cells encounter apoptotic stimuli or Ras is ectopically expressed. In some of these cases Ras acts through known effectors and well defined apoptotic death pathways. However, in other cases it appears that Ras operates by triggering novel non-apoptotic death mechanisms that are just beginning to be characterized. Understanding these mechanisms and the factors that go into changing the nature of Ras signaling from pro-survival to pro-death could set the stage for development of novel therapeutic approaches aimed at manipulating pro-death Ras signaling pathways in cancer.