2025 Theses Doctoral

Functional Dissection of Pancreatic Ductal Adenocarcinoma (PDAC) Progression Through In Vivo, Genome-wide CRISPR Screening and Multi-Omic Analysis of Eif4G2-Dependent Translational Programs

Powers, Justin Anthony

Pancreatic ductal adenocarcinoma (PDAC) is marked by early metastatic spread, intrinsic therapy resistance, and pronounced transcriptional plasticity, all of which contribute to its poor prognosis. I conducted an in vivo, genome-wide CRISPR-Cas9 screening to identify genetic regulators of PDAC progression, capturing both primary tumor growth and metastatic outgrowth. Using immunocompetent, syngeneic allograft models in both young and old hosts, I identified a broad set of tumor suppressors and promoters.

Among these, Eif4G2, a noncanonical translation initiation factor, emerged as a selective suppressor of aggressive tumor phenotypes. Loss of Eif4G2 led to poorly differentiated tumors with basal-like features, including squamous histology and increased expression of Krt14. To dissect the underlying mechanisms, I integrated RNA sequencing, ribosome profiling, and mass spectrometry-based proteomics in Eif4G2-deficient PDAC cell lines. These analyses revealed transcriptional upregulation of neuronal and basal programs alongside post-transcriptional alterations in a distinct subset of genes. Notably, Pten, Mib1, and Malat1 were translationally dysregulated in the absence of corresponding mRNA-level changes. Pten loss, alone, recapitulated tumor growth acceleration and poor-differentiation status, suggesting its contribution to the overall Eif4G2-deficient state which is dependent on transcriptional and translational modifications.

Together, these findings define Eif4G2 as a tumor suppressor that restrains lineage infidelity and phenotypic plasticity in PDAC. More broadly, this work establishes in vivo CRISPR screening as a powerful approach for identifying regulators of tumor cell fate and highlights the role of translational control as a functional axis of PDAC progression.