Targeting Metabolic Pathways through Pharmacological and Chemotherapeutic Interventions to Improve Triple-Negative Breast Cancer Therapy

Triple-negative breast cancers (TNBCs) are an aggressive breast cancer subtype with systemic chemotherapy as the only current treatment option. Metabolic reprogramming is key to tumor resistance to stressors including therapy. We hypothesized that targeting nutrient-sensing pathways through IGF-1R/IR and mTORC1 inhibition would increase efficacy of the platinum-based agent carboplatin and that autophagy underpins cell survival. We investigated combinatorial drug treatment effects on cytotoxicity, target inhibition, and mitochondrial function in MDA-MD-231 cells. IGF-1R/IR and mTORC1 inhibition with BMS-754807 and everolimus, respectively, increased the cytotoxicity of carboplatin while BMS-754807 interacted with the autophagy inhibitor chloroquine increasing growth inhibition. This work indicates that IGF-1R/IR and/or mTORC1 suppression is potentially synergistic with carboplatin in TNBC cells and suggests IGF-1R/IR inhibition can collaborate with autophagy inhibition to suppress TNBC growth. We conclude that inhibiting nutrient-sensing metabolic pathways with chemotherapy and/or autophagy inhibition warrants additional study as a strategy to improve response in women with TNBC.Master of Scienc

Examining the effects of anti-cancer combination therapy on tumor cell proliferation, migration and chemoresistance: Targeting Autophagy and Other Novel Pathways.

Autophagy is a cellular catabolic which is known to be activated by cellular stress and acts as a critical cell survival pathway. Solid tumours experience different microenvironmental metabolic stresses such as hypoxia and nutrient/energy deprivation. These highly stressful microenvironmental conditions could lead to activation of the pro-survival autophagic pathway, leading to cancer progression. Currently, clinically available autophagy inhibitors (e.g., chloroquine) only provides modest inhibitory activity. Hence, development of novel strategies to potently inhibit the autophagic pathway are warranted. This thesis explores the effect of anti-cancer combination therapy ,via targeting autophagy with specific autophagy inhibitors directed toward major molecules in the autophagic pathway and other novel pathways, on tumour cell proliferation, migration and chemoresistance

The effects of selective inhibitors of n-glycosylation and endoplasmic reticulum stress inducers on the expression of neuroblastoma drug resistance

Magister Scientiae - MSc (Medical BioSciences)Neuroblastoma (NB) represents 8-10% of all childhood tumours and accounts for approximately 15% of all cancer-related deaths in the paediatric population. Approximately half of newly diagnosed children with this tumour will present with metastatic disease or histologically aggressive large tumours that are at high risk for treatment failure. Since NBs are often widely disseminated and the tumours genetically heterogeneous in terms of their growth and metastatic behaviour, it is challenging to pinpoint their origin and predict disease prognosis. Several risk factors have been identified to play a role in disease progression, including age at the time of initial presentation, tumour stage, histology and ploidy of the tumour, and cytogenetic aberrations such as MYCN amplification, anaplastic lymphoma kinase (ALK), loss of heterozygosity of 11q and gain of 17q chromosomes

The effects of selective inhibitors of N-Glycosylation and Endoplasmic Reticulum stress inducers on Neuroblastoma cell proliferation and Apoptosis

Magister Scientiae - MSc (Medical BioSciences)Among all childhood cancers diagnosed, neuroblastoma (NB) is the most prevalent during infancy. In patients younger than 15 years, it accounts for more than 7% of malignancies and about 15% of all paediatric mortalities. A family history of NB is considered a genetic predisposition and risk factor. In 1-2% of inherited cases, the molecular causative factors linked to the disease are germline mutations, including anaplastic lymphoma kinase (ALK, gain of function), PHOX2B (loss of function) and MYCN (gain of function). NB differs from most solid tumours because of its heterogeneity in both pathobiologic and clinical behaviour, ranging from spontaneous regression to highly-aggressive metastatic disease resistant to conventional and investigational anticancer drugs. Hence, NB embodies a spectrum of disease

Diindolylmethane Analogs as Novel NR4A1 Antagonists and as a Novel Class of Anticancer Agents and Sp Transcription Factors as Nononcogene Addiction Genes That Are Targets of ROS Inducing Agents

The orphan nuclear receptor 4A1 (NR4A1) and specificity protein (Sp) transcription factors (TFs) are both overexpressed in the majority of solid tumors. Our laboratory has researched the molecular mechanisms of a novel class of 1,1-bis(3'-indolyl)-1-(p-substituted phenyl)methanes (C-DIMs) as NR4A1 antagonists and Sp proteins as non-oncogene addiction genes (NOA) that are targets of reactive oxygen species (ROS) inducing agents. Nr4A1 antagonists (DIM-C-pPhOH) (C-DIM 8) and (DIM-C-pPhCO2Me) (C-DIM 14) inhibited cancer cell proliferation, induced apoptosis, and inhibited migration. The NR4A1 antagonists inhibited constitutive and TGFβ-induced migration in Triple Negative Breast Cancer (TNBC) cells. We also demonstrate that p38α is necessary and sufficient for TGFβ-mediated migration and NR4A1 nuclear export in triple negative breast cancer (TNBC) which was attenuated with NR4A1 antagonists (C-DIMs), leptomycin B, and the p38 inhibitor SB202190. We also demonstrate that NR4A1 is essential for TGFβ-induced EMT and NR4A1 antagonists promoted cytosolic sequestration of the transcription factor β-catenin and its proteasome-dependent degradation in a time dependent manner. β-catenin, along with TCF-3, TCF-4, and LEF-1 binds to TCF/LEF response elements in the NR4A1 promoter, regulating its expression. RNA interference (RNAi) demonstrates that Sp1, 3, and 4 TFs individually play a role in cancer cell growth, survival and migration/invasion in cancer cell lines. Individual knockdown of Sp1, Sp3, or Sp4, resulted in inhibition of cell growth, migration, and induction of apoptosis, with no compensation. Moreover, tumor growth in athymic nude mice bearing pancreatic cancer xenografts was significantly attenuated in cells depleted of Sp1, Sp3, and Sp4 in combination or Sp1 alone. Ingenuity Pathway Analysis (IPA) of changes in gene expression in Panc1 pancreatic cancer cells after individual knockdown of Sp TFs demonstrates that Sp1-, Sp3- and Sp4-regulated genes were associated with pro-oncogenic activity. C-DIMs are promising anticancer agents in NR4A1-overexpressing solid tumors and represent a novel class of mechanistic-based drugs that target TGFβ/NR4A1-dependent inducible migration in TNBC. The functional and genomic results coupled with overexpression of Sp transcription factors in tumor vs. non-tumor tissues and decreased Sp1 expression with age indicate that Sp1, Sp3 and Sp4 are non-oncogene addiction (NOA) genes and are attractive drug targets for individual and combined cancer chemotherapies