Mapping Epigenetic and Functional Landscape of Tumor Immunotherapy Resistance Using CRISPR-Based Genome Editing Shangshang Wang

Format:

Book

Thesis/Dissertation

Author/Creator:

Wang, Shangshang, author.

Contributor:

University of Pennsylvania. Chemistry., degree granting institution.

Language:

English

Subjects (All):

0369.

0982.

0992.

Local Subjects:

0369.

0982.

0992.

Physical Description:

1 electronic resource (176 pages)

Contained In:

Dissertations Abstracts International 87-07B

Place of Publication:

Ann Arbor : ProQuest Dissertations and Theses, 2025

Language Note:

English

Summary:

Immune checkpoint blockade (ICB) therapies have changed the landscape of cancer therapy. However, most tumors either exhibit primary or acquire resistance to these therapies, hence restricting their practical use. Understanding these complex mechanisms will provide opportunities to find actionable targets to sensitize tumors to immune attack. This dissertation utilized a combination of functional genomic screens, mechanistic studies, and in vivo tumor models to characterize the epigenetic regulators of immune checkpoint block (ICB) resistance and their contributions to the tumor-immune microenvironment.Through in vivo CRISPR screens in ICB-resistant and naïve tumor models, we identify the histone methyltransferase SETDB1 as a critical mediator of tumor immune evasion. SETDB1 inhibits the transcriptional activation of transposable elements (TEs) and prevents the downstream production of double-stranded RNA (dsRNA) that generates neoantigens and is recognized by immune capacities. The loss of SETDB1 in tumors induces the activation of TEs, upregulates IFN signaling, and enhances tumor immunogenicity. In tumors with higher basal levels of interferon signaling, depletion of SETDB1 further amplifies cytotoxic programs driven by IFN and sensitizes tumors to NK cell-mediated killing.While functional screens clearly identify cancer dependency, applying these findings to therapeutic approaches requires a specific understanding of the target genes at the domain/residue level. To address these challenges, we have developed a novel split-engineered CRISPR base editing (seBE) platform that systematically targets protein domains and the critical residues required for ontogenesis. Here, splitting deaminase into two inactive fragments, which can be reassembled by small molecule-induced heterodimerization, reduces off-target toxicity while enabling inducible and tunable editing. When applying seBEs to tile mutagenesis of multiple cancer dependencies, we identified critical residues that enhanced tumor fitness while influencing immune interactions.Overall, this work combines functional genomics, epigenetic regulation, and immunology to elucidate how SETDB1 and TE silencing influence tumor immune evasion and ICB response, while providing a resourceful tool for systematically mapping functionally important protein residues. The work lends a mechanistic and translational understanding of overcoming immunotherapy resistance and lays the groundwork for functional interrogation of cancer dependencies

Notes:

Advisors: Minn, Andy J.; Marmorstein, Ronen Committee members: Shi, Junwei; Jin, Chengcheng; Matthews, Megan L.

Source: Dissertations Abstracts International, Volume: 87-07, Section: B.

Ph.D. University of Pennsylvania 2025

Vendor supplied data

Local Notes:

School code: 0175

ISBN:

9798276006239

Access Restriction:

Restricted for use by site license