Mapping the Molecular Mechanism of GTPases KRAS and RIT1 in Lung Cancer
出版項
2021
說明
1 online resource (101 pages)
文字
text
無媒介
computer
成冊
online resource
附註
Source: Dissertations Abstracts International, Volume: 82-11, Section: B
Advisor: Berger, Alice
Thesis (Ph.D.)--University of Washington, 2021
Includes bibliographical references
RAS genes are mutated in 30% of human cancers, and RAS genes are amongst the most important oncogenes. KRAS and RIT1 (Ras-like in all tissues) have been identified as cancer drivers in 30% and 2% of lung adenocarcinoma, respectively. RIT1 is traditionally studied using the homology between KRAS to inform functional mutations and effector proteins. Defining mutant KRAS or RIT1-specific signaling and critical effector proteins is important, because targeting RAS effector proteins may provide a therapeutic opportunity.Recently it has been shown that KRAS forms homodimers, and KRAS homodimers are required for mutant KRAS- driven tumorigenesis. Preliminary mass spectrometry data identified NRAS as a KRAS interacting protein, raising the possibility that RAS proteins can heterodimerize. In order to investigate if KRAS and NRAS heterodimerize, I employed the biochemical assays of size exclusion chromatography and co-immunoprecipitation. Size exclusion chromatography resolved Ras homodimers, confirming the catalytic RAS G-domain has an innate ability to form dimers. Future work in optimizing recombinant protein expression is necessary to distinguish RAS homodimers from putative KRAS/NRAS homodimers. Unfortunately, co-immunoprecipitation cannot detect KRAS homodimers or putative KRAS/NRAS heterodimers. Additionally, loss of NRAS in A549 lung adenocarcinoma cells led to a decrease in proliferation, confirming the functional role of NRAS in mutant KRAS cancer. Continuing to characterize RAS dimers may uncover opportunities to abrogate Ras heterodimers for therapeutic benefit. Global proteomic profiling was performed in order to identify RIT1 and KRAS specific signaling in lung cancer cells. Mutant RIT1 drives epithelial-to-mesenchymal transition (EMT) similar to mutant KRAS by modulating key EMT genes such as Vimentin, Fibronectin1, N-Cadherin, Keratin19. Interestingly, mutant RIT1 and KRAS induced down-regulation of HLA proteins. Additional work is necessary to elucidate the mechanism of loss of MHC class I complex. Phosphoproteome analysis revealed differential phosphorylation of several EGFR phosphorylation sites. Understanding the similarities and differences in the signaling pathways modulated by mutant RIT1 and mutant KRAS can help to elucidate a therapeutic strategy for RIT1-driven lung adenocarcinoma
Electronic reproduction. Ann Arbor, Mich. : ProQuest, 2021
