PHYTOCHEMICAL AND SYNTHETIC INVESTIGATIONAL COMPOUNDS AS MODULATORS OF CYTOMETABOLIC AND CYTOSKELETAL DYNAMICS FOR PRE-CLINICAL TARGETING OF PROSTATE CANCER

Prostate cancer (PC) is the most commonly found malignancy among men globally. Many genetic and epigenetic factors involving multiple cellular signaling networks are implicated in the initiation, progression, and metastasis of this disease. Therapeutic drug resistance and hormone-sensitive and/or refractory metastases present a major stumbling block in disease management. However, the heterogeneity and complexity of this disease make it impossible to inhibit cancer cell survival signaling pathways with monotherapy. Combination therapy offers a strategy to improve malignant cell death via interfering with multiple pro-survival pathways. Natural health products and nutraceuticals present tangible options as potential candidates for combination therapy to treat cancer. These products are generally known to be well-tolerated with chronic use by consumers. For this reason, we chose the bioactive phenolic plant compound, lignan, for our investigations. As a metabolic disease, cancer cells rewire metabolic networks to support bioenergetics and biosynthetic requirements for their survival and progression (cells increase in malignancy via progressive alterations). Consequently, cancer cells can utilize different energy substrates such as glucose, pyruvate, and glutamine based on their need and availability. Given this, my Ph.D. dissertation research assessed the comparative cytotoxicity under different energy substrate conditions, cellular targets, and putative mechanisms of action for the lignans, enterolactone and isoalantolactone, and to identify other potential drug candidates for targeting PC cytometabolic and cytoskeletal stress vulnerabilities, in several different heterogeneous sub-types of PC by the use a myraid of in vitro cell and molecular biology techniques. We demonstrated that: (a) lignans and other potential drug candidates differentially influence PC cell survival by targeting cellular energy metabolism influenced by normal and high glucose, and (b) lignans and other investigational pharmacological compounds negatively influenced PC cell survival by targeting cellular energy metabolism influenced by energy substrates like glucose, pyruvate, glutamine, and galactose. The experimental evidence suggests that lignans (and other investigational compounds) reduced ATP, interfered with mitochondria by reducing activity and membrane potential, modulated ROS and lipid storage in cells, negatively influenced key target genes associated with lipid and glucose metabolism (SREBP1/2, INSIG1, FASN, PKM2, PPARα/γ, mTOR, MAF, PDK1, LDLR, and SRB1), induced ER stress by elevating key targets in ER stress signaling (CHOP, ATF4, GRP94, GRP58, GADD 34, and PGC1α), increased glucose uptake and glycolysis due to severe nutrient and energy reduction in cells, and interfered with the cellular recovery process, autophagy, thus leading to reduced cell proliferation, activation of caspases, and reduced cell viability. Collectively, these data suggest lignans and other investigational compounds modulate metabolic dynamics in PC cells. We also provide evidence to support lignans (and other investigational drug candidates) differentially influence PC cell survival (and possibly progression) by targeting metabolic stress mechanisms, specifically mitochondrial and endoplasmic reticulum dynamics. The experimental evidence suggests that lignans negatively influence cell motility by repressing cell invasion associated genes, (modulate epithelial cell metastatic and anti-metastatic genes) such as TGFβ, SMAD3, VIMENTIN, E-CADHERIN, SNAIL, modulating F-actin, disfavoring anoikis resistance, and disfavoring EMT through limiting cell adhesion. Furthermore, we demonstrated that lignans and other investigational compounds differentially influence PC cell survival by modulating cytoskeletal dynamics and influence cell motility to reduce cancer cell survival and progression by targeting invasion, migration, extracellular matrix, and Wnt signaling. The experimental evidence suggests that enterolactone enhances the cancer killing effects of anti-mitotic chemotherapeutics such as docetaxel in PC cells involving multiple cell death pathways, and by suppressing FOXM1 and PCNA. Finally, we demonstrate that lignans and other investigational compounds perturb cancer cell survival through enhancing the anti-cancer effects of known clinically used anti-cancer agents such as microtubule targeted drugs and androgen receptor signaling blockers. The experimental evidence suggests that enterolactone enhanced the cancer killing effects of docetaxel, enzalutamide, and abiraterone anticancer drugs with synergism in PC cells, by involving multiple cell death pathways. With further studies, the roles and crosstalk of signaling pathways involving lignan’s and other investigational drugs (nelfinavir, piperlongumine, and ursolic acid) mechanisms of actions can be clarified and used as putative therapeutic targets for prostate cancer. In summary this thesis provides evidence to support the ideas that: a) PC cells differentially utilize glucose, pyruvate, and glutamine; b) lignans and other compounds target metabolism associated with glucose, pyruvate, and/or glutamine; c) PC cells can be vulnerable to the targeting of their cytometabolic processes; d) Lignans and other compounds negatively impact PC cell cycle, epithelial to mesenchymal transition and cell motility, and promote epithelial formation; e) PC cells can be vulnerable to targeting of their cytoskeletal dynamics; and f) Lignan’s enhance the cytotoxic effects of clinically used PC therapeutics such as Taxol and androgen targeted therapies. Therefore, this evidence will lay foundation for further investigations in pre-clinical in vivo cancer models and thereafter in clinical trials to assess use of lignan enriched products as combination therapy for improved treatment of prostate cancer.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Pharmacy

Grantor

University of Saskatchewan

Year dc:date.issued

2023

Author dc:creator

• De Silva, Shanal Franklyn

Advisor dc:contributor.advisor

• Alcorn, Jane

Committee members dc:contributor.committeemember

• Freywald, Andrew
• Arnason, Terra
• Yang, Jian
• Dadachova, Kate
• Spagnuolo, Paul

• Cancer, Metabolism, Prostate, cytoskeleton, mitochondria, endoplasmic reticulum, lignan, lipids, glucose, pyruvate, glutamine, autophagy, heterogeneous, chemotherapeutics, Cell stress

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/14568

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/14568