Ermine, Kaylee A.
(2023)
Restoring Necroptosis to Overcome Chemotherapeutic Resistance in Colorectal Cancer.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Colorectal cancer (CRC) is a leading cause of cancer-related deaths in the United States. Metastatic CRC is commonly treated with 5-fluorouracil (5-FU)-based therapies, but resistance is a major problem, often due to evasion of cell death and immune destruction. Although it is well-established that 5-FU exerts its cytotoxicity through apoptosis, studies have shown that cell death can still occur when apoptosis is blocked, suggesting a role for non-apoptotic cell death, such as necroptosis. Necroptosis is a regulated form of necrosis, controlled by Receptor Interacting Protein kinase 1 (RIP1), RIP3, and Mixed Lineage Kinase domain-Like pseudokinase (MLKL). Unlike apoptosis, necroptosis results in plasma membrane rupture, causing release of Damage Associated Molecular Patterns (DAMPs), which can stimulate an immune response. Although necroptosis has been studied under normal conditions and in several diseases, its role in cancer is not quite clear. We determined that key necroptosis protein RIP3 is downregulated in ~50% of colorectal tumors, which is associated with poor clinical outcomes. RIP3 downregulation also occurs in established CRC cell lines. Therefore, we hypothesized that necroptosis plays a critical role in anticancer therapy and that restoring defective necroptosis could enhance therapeutic sensitivity. In this study, we established that 5-FU induces both apoptosis and necroptosis in CRC cells in a RIP3-dependent manner, as loss of RIP3 not only abrogated necroptosis induction but also reduced 5-FU sensitivity. Additionally, we found that restoration of RIP3 expression in RIP3-silenced CRC cells restored necroptosis induction, but only enhanced 5-FU sensitivity under conditions where apoptosis was inhibited. Furthermore, we identified synergy with a novel drug combination of 5-FU and natural compound OSW-1, which simultaneously induced both apoptosis and necroptosis in RIP3-silenced CRC cells. This combination resulted in significant tumor growth inhibition and a robust CD8+ T cell-dependent antitumor immune response in syngeneic mouse models. Together, these findings provide novel insights into the role of necroptosis in anticancer therapy in CRC, demonstrating a rationale for inducing necroptosis in the clinic.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
17 November 2023 |
| Date Type: |
Publication |
| Defense Date: |
20 June 2023 |
| Approval Date: |
17 November 2023 |
| Submission Date: |
29 June 2023 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
148 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Medicine > Molecular Pharmacology |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Cell Death; Necroptosis; Colorectal Cancer; Chemotherapy; Immunogenic Cell Death |
| Date Deposited: |
17 Nov 2023 18:45 |
| Last Modified: |
17 Nov 2023 18:45 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/45055 |
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