Hockenbery, DavidGrissett, Laquita Monique2022-09-232022-09-232022-09-232022Grissett_washington_0250E_24776.pdfhttp://hdl.handle.net/1773/49236Thesis (Ph.D.)--University of Washington, 2022Fanconi anemia (FA) is a rare genetic disorder. Patients with FA are cancer-prone and commonly develop acute myeloid leukemia and several solid tumors, including head and neck squamous cell carcinoma (HNSCC). Typically, the FA DNA repair pathway, which is responsible for the repair of DNA interstrand crosslinks, is ubiquitously found in all tissues; however, FA patients lose the FA DNA repair pathway in all their tissues. Despite the absence of this pathway in all their tissues, the epithelium of the head and neck is disproportionately burdened with solid tumors, and little is known regarding why this epithelium is a major site for cancer in FA patients. The objective of my dissertation is to elucidate cellular mechanisms that explain why FA patients are highly susceptible to HNSCC. Formaldehyde and acetaldehyde are two aldehydes generated via normal cellular metabolic activity, and it has been proposed that both aldehydes are predominant contributors to DNA crosslinking events in humans. I measured endogenous aldehyde production, and I tested the effect of formaldehyde and acetaldehyde on human cell lines including oral keratinocyte cell lines and an epidermal keratinocyte cell line to understand more about the activity of the FA DNA repair pathway and the impact of these genotoxins (i.e., formaldehyde and acetaldehyde) on the genome. Oral keratinocytes were compared to epidermal keratinocytes because there is not a high incidence of epidermal squamous cell carcinoma reported in FA patients. I found that endogenous aldehyde production is unlikely to be a contributing factor to HNSCC in FA patients based on data extrapolated from cell lines. I found that oral keratinocytes are more resistant to formaldehyde and acetaldehyde compared to the epidermal keratinocytes. Resistance to exogenous formaldehyde and acetaldehyde correlated with increased activation of the FA DNA repair pathway and γH2AX in the oral keratinocyte cell lines, which suggests that the oral keratinocyte cell lines may be more dependent on the FA DNA repair pathway for protection against exogenous sources of aldehydes. Conversely, the failure of the same concentration of exogenous aldehydes to activate the FA DNA repair pathway in the epidermal keratinocyte cell line suggests dependence on enzymes that catabolize aldehydes, and aldehyde dehydrogenase 2 has been reported to be expressed in the epidermis at higher levels compared to the oral mucosa. My research findings suggest that exogenous sources of aldehydes and the reliance on the FA DNA repair pathway for protection in the oral keratinocytes may explain the increased frequency of HNSCC in FA patients. This work is a leap towards understanding the complex intersection of genomic and genotoxic factors that contribute to and drive HNSCC development in FA patients, and findings could potentially lead to the development of therapeutic interventions.application/pdfen-USnoneacetaldehydecancer biologyFA DNA repair pathwayFanconi anemiaformaldehydehead and neck squamous cell carcinomaDentistryBiologyGeneticsThesis