orals 5th Asia-Pacific NMR Symposium 2013

Dissecting RAS Cancer Cell Signaling by NMR: New Approach Towards ‘Personalized Medicine’ (#12)

Christopher B Marshall 1 , Mohammad Mazhab-Jafari 1 , Mathew J Smith 1 , Mitsu Ikura 1
  1. Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, M5G 1L7

RAS proteins have been long known as a major oncogenic determinant in ~30% of all human tumours. However, the development of clinically effective, RAS-directed cancer therapies has been largely unsuccessful, and RAS-pathway driven cancers remain among the most refractory to available treatments. This is largely owing to the fact that ‘transformed’ RAS-pathways are ill-characterized due to the lack of appropriate functional assays for the affected pathways. NMR spectroscopy is a versatile technique that enables the determination of three-dimensional structures, as well as the dynamic properties of biological macromolecules. NMR can also be used to study enzymatic kinetics and the underlying mechanisms of catalysis, such as Ras GTPase cycle. In our laboratory we use NMR to maximize its technical versatility, through which we can acquire more detailed pictures of the biological systems of our interest. In this talk, I will discuss how we employed NMR spectroscopy to delineate the oncogenic Ras pathways and how we might be able to use the information towards personalized cancer therapy. In particular, I will discuss our real-time NMR-based GTPase assays for the Ras function using mammalian cell extracts with particular attention to the characterization of oncogenic Ras and Noonan syndrome-derived mutations in the Ras guanine nucleotide exchange factor Son-of-Sevenless (SOS). We also employed the nanodisc technology to study membrane-anchored GTPases, which enable us to characterize how a small GTPase function and structure is modulated by the biological membrane. These structural and functional characterizations by NMR help to develop therapeutic strategies towards developing anti-cancer agents and also diagnostic tools for patient cohort identification in heterogeneous cancers (Supported by CFI, CIHR, CCSRI, HSFO, and CRS).