Dissertation
Mechanisms of resistance to targeted therapies for uveal melanoma
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2025
DOI: 10.25820/etd.007866
Abstract
Uveal melanoma (UM) is the most common intraocular malignancy in adults. Originating from melanocytes within the uveal tract, UM is associated with poor prognosis, chemoresistance, and high mortality, particularly in metastatic stages. Over 90% of UM cases exhibit mutually exclusive mutations in the GNAQ or GNA11 genes, which activate various signaling pathways,such as MAPK, PI3K, and YAP, through FAK. Conflicting research exists regarding the key signaling pathways and the resistance mechanisms proteins use to overcome inhibition through these pathways. These discrepancies underscore the need for a novel approach to clarify the significant signaling mechanisms and identify resistance mechanisms in UM. In this study, we address these issues by performing unbiased forward genetic approaches using the Sleeping Beauty (SB) mutagenesis system with targeted therapies to identify genetic drivers of resistance. The following chapters will explore how the SB-identified genes drive drug resistance, the mechanistic pathways they employ, and their relationship to cancer stem cells.
In Chapter 1, I review UM characteristics, risk factors, molecular mechanisms, and the association of metastasis. Additionally, I detail what is known about SB and its applications. In Chapter 2, I investigate resistance mechanisms using SB in UM to GNAQ/11 inhibition through a selective inhibitor, FR. I determined that the over-expression of select candidates from the FR SB screen led to a higher rate of resistant colony emergence than parental cells. I investigated the top driver of FR resistance identified in the SB screen and observed a distinct gene expression profile associated with its over-expression. In Chapter 3, I identify genetic factors contributing to resistance to PKC and MEK inhibitors in an animal model of UM. Using the SB screen, I identified several potential candidates that may be linked to tumor engraftment rather than drug resistance. In contrast, only one candidate conferred resistance to PKC/MEK inhibition and PKC/TK inhibition. In Chapter 5, I conclude the dissertation by exploring the potential implications of these findings for both basic and translational research.
Details
- Title: Subtitle
- Mechanisms of resistance to targeted therapies for uveal melanoma
- Creators
- Sarina Dion Murray
- Contributors
- Adam Dupuy (Advisor)Christopher Stipp (Advisor)Michael Henry (Committee Member)Miles Pufall (Committee Member)Joseph Caster (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Biomedical Science (Cancer Biology)
- Date degree season
- Spring 2025
- DOI
- 10.25820/etd.007866
- Publisher
- University of Iowa
- Number of pages
- xi, 95 pages
- Copyright
- Copyright 2025 Sarina Dion Murray
- Grant note
- This work was partly supported by funding from the Department of Defense (W81XWH-22-1-0782) and the contributions of patients and families to the Iowa Melanoma Research Fund. Thank you to the generosity of primary investigators Kendall J. Blumer and Michael D. Onken from Washington University School of Medicine for gifting our UM cells, 92.1 and MEL202, and the therapeutic target, FR.
- Language
- English
- Date submitted
- 04/01/2025
- Description illustrations
- illustrations, graphs, tables
- Description bibliographic
- Includes bibliographical references (pages 83-95).
- Public Abstract (ETD)
- Uveal melanoma (UM) is the most common form of intraocular cancer in adults, characterized by poor prognosis and chemoresistance, especially in metastatic stages. Despite various treatments, the median survival rate after metastasis is approximately one year, and no effective pharmacological therapies are currently available. Activating mutations in GNAQ and GNA11 proteins (GNAQ/11) drive over 90% of UM cases. In this study, we utilized a functional genomics approach to identify drivers of resistance to the GNAQ/11 inhibitor, FR900359 (FR), in UM cell lines (92.1 and MEL202). Eleven candidate genes were identified, with over- expression of four genes (ABCB1, PLCB4, GRM1, PLCE1) predicted to confer resistance to FR treatment. Notably, over-expression of ABCB1 and PLCB4 led to the emergence of resistant colonies following FR exposure, suggesting that genetic alterations contribute to acquired resistance. These findings highlight that resistance to GNAQ/11 inhibitors results from genetic and epigenetic interactions within heterogeneous UM cell populations, suggesting the complexity of overcoming drug resistance in UM. Additionally, we performed an in vivo Sleeping Beauty mutagenesis screen to uncover genetic factors contributing to resistance to PKC and MEK inhibitors (sotrastaurin and binimetinib). Although ZFHX3, GATA4, PTAFR, and AFF4 were identified as potential drivers of resistance, only PTAFR offered resistance, especially in BAP1-deficient UM cells treated with darovasertib and crizotinib. These findings underscore the complexity of resistance mechanisms in UM and suggest that targeting multiple pathways may be necessary for effective treatment.
- Academic Unit
- Biomedical Science Program
- Record Identifier
- 9984830924802771
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