Graduation Date

Summer 8-9-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Biochemistry & Molecular Biology

First Advisor

Amar B Singh

Abstract

Despite significant progress in clinical management, colorectal cancer (CRC) remains the 3rd most common cause of cancer-related deaths. A positive association of PYCR2 (Pyrroline-5-carboxylate reductase-2), a terminal enzyme of proline metabolism, with CRC aggressiveness was recently reported including by us. However, how PYCR2 promotes colon carcinogenesis remains ill understood. In our studies, comprehensive in-silico and biochemical evaluations were performed along with genetic manipulations and in-vivo tumor growth assays to gain mechanistic understanding. Results showed that PYCR2 expression was significantly upregulated in CRC and associated with poor patient survival specifically among PYCR isoforms (PYCR-1, -2 and -3). Genetic inhibition of PYCR2 inhibited tumorigenic abilities of CRC cells and in-vivo tumor growth potential. Coinciding with these observations was a significant decrease in cellular proline content. In complementary studies, PYCR2 overexpression in CRC cells promoted their tumorigenic abilities. Proteomics (LC MS/MS) analysis using the lysates from control and PYCR2 manipulated CRC cells further demonstrated that PYCR2 loss-of-expression in CRC cells inhibited survival and cell cycle pathways along with modulation of biochemical metabolic pathways. Subsequent biochemical analysis demonstrated that PYCR2 regulates Wnt/β-catenin-signaling in manners dependent on the expression of MASTL (Microtubule Associated Serine/Threonine Like), known to promote CRC. Overall, our data suggested that PYCR2 promotes MASTL/Wnt/β-catenin signaling to regulate cancer cell stemness and thus colon carcinogenesis. Additional studies further demonstrated that PYCR2 expression induces a significant shift in metabolic activities of CRC cells in causal association with GLUT3 expression. Taken together, our data highlights the significance of PYCR2 as a novel regulator of CRC progression and potential therapeutic target for effectively treating colon cancer.

Comments

2024 Copyright, the authors

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Available for download on Monday, February 10, 2025

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