Medicine and Health Sciences Commons^™

The Role Of The Diras Family Members In Regulating Ras Function, Cancer Growth And Autophagy, Margie Nicole Sutton

Dissertations & Theses (Open Access)

DIRAS3 is a maternally imprinted tumor suppressor gene that is downregulated by multiple mechanisms across several tumor types. When re-expressed, DIRAS3 decreases proliferation, inhibits motility, and induces autophagy and tumor dormancy. DIRAS3 encodes a 26 kDa small GTPase with 60% homology to Ras and Rap, differing from oncogenic Ras family members by a 34-amino acid N-terminal extension that is required for its tumor suppressive function in ovarian cancer. By assessing the structure-function relationship, I found that DIRAS3 inhibits Ras-induced transformation and is a natural antagonist of Ras/MAPK signaling. DIRAS3 binds directly to Ras and disrupts cluster formation inhibiting the activation …

Structure Based Prediction Of Drug-Protein Interactions At Allosteric Sites: Towards Direct Inhibition Of The Ras Oncogene, Harrison Hocker

Dissertations & Theses (Open Access)

Ras is a monomeric G-protein that mediates multiple signaling pathways. When bound to GTP, Ras binds to and activates effectors and when bound to GDP it does not. Somatic mutations occur in ~15% of all human cancers and cause Ras to be predominantly bound to GTP. Recently, several studies revealed that Ras exists in an ensemble of at least two states when bound to GTP. In the state 1 conformation, Ras is unable to properly bind effectors but holds potential for binding ligands. Conversely, at allosteric sites, state 2 conformations readily bind effectors but not ligands.

To incorporate the flexibility …

Increased Geranylgeranylated K-Ras Contributes To Antineoplastic Effects Of Farnesyltransferase Inhibitors., Mandy A. Hall

Dissertations & Theses (Open Access)

The Ras family of small GTPases (N-, H-, and K-Ras) is a group of important signaling mediators. Ras is frequently activated in some cancers, while others maintain low level activity to achieve optimal cell growth. In cells with endogenously low levels of active Ras, increasing Ras signaling through the ERK and p38 MAPK pathways can cause growth arrest or cell death. Ras requires prenylation – the addition of a 15-carbon (farnesyl) or 20-carbon (geranylgeranyl) group – to keep the protein anchored into membranes for effective signaling. N- and K-Ras can be alternatively geranylgeranylated (GG’d) if farnesylation is inhibited but are …