Thesis
Ectopic expression of ERK regulates an altered epigenetic program analogous to oncogene addiction leading to phenotypic conversion in C10 cells
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/100477
Abstract
The Extracellular Signal Regulated Kinase (ERK) is a downstream mediator of oncogenes such as Ras and in some cases, constitutive ERK activation is sufficient to recapitulate oncogenic programming driving neoplasia. Here we explore the possibility that ectopic ERK expression regulates epigenetic programming to determine whether this event is sufficient to induce phenotypic conversion. We also investigated the differential sensitivity of phenotypically transformed cells to a DNA methyl transferases (DNMT) inhibitor (5-azacytidine; 5-azaC) and histone deacetylase (HDAC) inhibitor (Trichostatin A), as a measure of biochemical dependence, analogous to oncogene addiction. Following transduction of C10 cells with an ERK1-green fluorescent protein (ERK1- GFP) chimera, a morphological change appeared with prolonged passaging that coincided with the acquisition of focus-forming activity in late passage cells, while early passage ERK1-GFP cells and vector controls exhibited poor focus-forming potential. We observed significant increases in the expression of DNMT 1 and 3b in late passage ERK1-GFP cells, relative to early passage cells and vector controls. Late passage ERK1-GFP cells displayed a marked increase in sensitivity to cell killing induced by 5-azaC, but not Trichostain A, suggesting phenotypic conversion is associated with dependence on DNMT activity. Focus forming potential of late passage ERK1-GFP cells was also inhibited by 5-azaC. The expression of xeroderma pigmentosum complementation group A (XPA) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) were significantly increased only in late passage cells. It is possible that increased expression of DNA repair proteins may reflect increased DNA breaks and damage recognition occurring during phenotypic conversion, although a causal role cannot be defined from these studies. Collectively these observations suggest that ectopic ERK expression is sufficient to drive the transformation of C10 cells, and that survival under these conditions is highly dependent upon an altered epigenetic program.
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Details
- Title
- Ectopic expression of ERK regulates an altered epigenetic program analogous to oncogene addiction leading to phenotypic conversion in C10 cells
- Creators
- Ryan Lyle Sontag
- Contributors
- James R. Pratt (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525106501842
- Language
- English
- Resource Type
- Thesis