UBC Theses and Dissertations
Cell of origin in pancreatic ductal adenocarcinoma Lee, Alex Y. L.
Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease with a ductal morphology. Prior research has identified both pancreatic acinar and ductal cells as possible cells of origin for histologically similar PDAC. However, because different mutations were induced in acinar and ductal cells, apt comparisons could not be made to address whether the tumor cell of origin influences PDAC initiation, development, and other tumor differences. To address this open question, I induced oncogenic Ras expression (KrasG¹²D) with concomitant homozgyous Trp53 deletion at 4 weeks of age in a ductal cell specific (Sox9CreER; KrasLSL-G12D; Trp53flox/flox (“Duct:KPcKO”)) and an acinar cell specific (Ptf1aCreER; KrasLSL-G12D; Trp53flox/flox (“Acinar:KPcKO”)) mouse model. I found that Duct:KPcKO mice met their humane endpoints earlier (82 days post injection, p.i.) than the Acinar:KPcKO mice (128 days p.i.), for reasons associated with differences in the timing of PDAC onset. While tumors from both cells of origin were similarly proliferative and shared many physical characteristics, Duct:KPcKO mice developed tumors much earlier than Acinar:KPcKO mice and this was further associated with a difference in precursor lesion initiation. Specifically, ductal cells only formed high-grade lesions while acinar cells formed precursor lesions of all grades. These findings suggest that cell type intrinsic differences may allow ductal cells to rapidly form PDAC under genetically favorable conditions. In comparison, acinar cells likely require additional steps to alter cell identity and become duct-like – thus delaying PDAC initiation and extending survival. Taken together, I have demonstrated, by using cell type specific mouse models, that cell of origin can alter disease initiation, progression and impact PDAC phenotype.
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