Author ORCID Identifier

https://orcid.org/

0000-0002-5643-0232

Date of Graduation

6-2022

Document Type

Dissertation (PhD)

Program Affiliation

Cancer Biology

Degree Name

Doctor of Philosophy (PhD)

Advisor/Committee Chair

Anirban Maitra

Committee Member

Cullen Taniguchi

Committee Member

Ken Chen

Committee Member

Paul Scheet

Committee Member

Chad Huff

Committee Member

Sinchita Roy-Chowdhuri

Abstract

Heterogeneity is a hallmark of cancer, and the advent of multimodal single-cell technologies has helped uncover heterogeneity in a high-throughput manner in different cancers across varied contexts at an unprecedented resolution. In an effort to improve precision medicine approaches in pancreatic ductal adenocarcinoma (PDAC), a highly lethal malignancy with a mere 11% 5-year survival rate, this dissertation focuses on first questioning the assumptions of the most basic models used to study PDAC via multimodal single-cell characterization methods at multiple levels of biological organization (scCNVseq and snATACseq for DNA assays, scRNAseq for transcriptomics, and paired protein assays such as multiplexed immunofluorescence and fluorescence in situ hybridization for validation methods) to reveal inherent heterogeneity in assumptively isogenic pancreatic cancer (PDAC) cell lines, patient-derived organoids (PDOs), and patient tissue samples that contribute to the proliferation of resistant cell phenotypes and, ultimately, treatment failures in the clinic. I then apply single-cell characterization methods to a panel of PDO samples to explore adaptive resistance mechanisms of PDAC lesions following administration of epigenetically-modifying therapeutic agents (HDAC inhibitors). I describe a novel HDACi resistance mechanism of AP1 activation, which can be intercepted by using an AP1 inhibitor in combination with an HDAC inhibitor to achieve tumor cell death. Finally, in an effort to explore and characterize the molecular consequences of newly-developed KRAS inhibitors in PDAC samples, I present a series to studies illustrating differential PDO sensitivity to KRAS inhibitors with different mechanisms of action, induce KRASi-resistance in select G12C-mutant PDO samples, and suggest avenues for future study to achieve maximal clinical benefit for PDAC patients on KRAS-inhibitory therapies.

Keywords

pancreatic cancer

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