Browsing by Subject "Cancer Stem Cell"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Role of Tumor Oxygen Tension in Signaling and Response to Targeted Therapies
    (2024-10) Adebayo, Adedeji Kolawole; Nakshatri, Harikrishna; Quilliam, Lawrence; Capitano, Maegan; Kim, Jaeyeon
    Most tumor cells in solid tumors are exposed to oxygen levels ranging from 0.5% to 5%, but never to ambient air oxygen levels of about 21%. We developed an approach that allows collection, processing and evaluation of cancer and non-cancer cells under physioxia (3%-5% oxygen), ensuring little to no exposure to ambient air. This approach allowed for comparison of baseline and targeted therapy-induced changes in signaling pathways in cells under physioxia and ambient air and to identify potentially efficacious therapeutic combinations based on signaling pathways uniquely active under physioxia. Using tumor cells from two transgenic models of breast cancer and cells from breast tissues of clinically breast cancer-free women, we demonstrate oxygen level-dependent differences in cell preference for EGFR or PDGFRβ signaling. Physioxia caused PDGFRβ-mediated activation of AKT and ERK that reduced tumor cell sensitivity to EGFR and PIK3CA inhibition and maintained PDGFRβ+ epithelial-mesenchymal hybrid cells with potential cancer stem cell properties. Cells in ambient air displayed differential EGFR activation and were sensitive to EGFR and PIK3CA inhibition. Tumor cells grown under physioxia were sensitive to high affinity PDGFRβ inhibitor sunitinib. Furthermore, significantly higher synergistic growth inhibition and apoptosis was observed with lapatinib (a clinically used dual EGFR and ErbB2/HER2 inhibitor) and sunitinib combination only in tumor cells under physioxia both in vitro and in vivo. Our data emphasize the importance of oxygen considerations in preclinical cancer research to evaluate clinically relevant signaling pathways and identify novel drug targets or combination therapy approaches. We suggest that evaluation of candidate drugs for their efficacy under physiologic oxygen levels in preclinical models, prior to transitioning into clinical trials, would not only accelerate the development of effective drugs but also reduce failure at the clinical trial stage.
  • Thumbnail Image
    Item
    Targetable Multi-Drug Nanoparticles for Treatment of Glioblastoma with Neuroimaging Assessment
    (2020-05) Smiley, Shelby B.; Lin, Chien-Chi; Veronesi, Michael; Agarwal, Mangilal
    Glioblastoma (GBM) is a deadly, malignant brain tumor with a poor long-term prognosis. The current median survival is approximately fifteen to seventeen months with the standard of care therapy which includes surgery, radiation, and chemotherapy. An important factor contributing to recurrence of GBM is high resistance of GBM cancer stem cells (CSCs), for which a systemically delivered single drug approach will be unlikely to produce a viable cure. Therefore, multi-drug therapies are needed. Currently, only temozolomide (TMZ), which is a DNA alkylator, affects overall survival in GBM patients. CSCs regenerate rapidly and over-express a methyl transferase which overrides the DNA-alkylating mechanism of TMZ, leading to drug resistance. Idasanutlin (RG7388, R05503781) is a potent, selective MDM2 antagonist that additively kills GBM CSCs when combined with TMZ. By harnessing the strengths of nanotechnology, therapy can be combined with diagnostics in a truly theranostic manner for enhancing personalized medicine against GBM. The goal of this thesis was to develop a multi-drug therapy using multi-functional nanoparticles (NPs) that preferentially target the GBM CSC subpopulation and provide in vivo preclinical imaging capability. Polymer-micellar NPs composed of poly(styrene-b-ethylene oxide) (PS-b-PEO) and poly(lactic-co-glycolic) acid (PLGA) were developed investigating both single and double emulsion fabrication techniques as well as combinations of TMZ and RG7388. The NPs were covalently bound to a 15 base-pair CD133 aptamer in order to target a specific epitope on the CD133 antigen expressed on the surface of GBM CSC subpopulation. For theranostic functionality, the NPs were also labelled with a positron emission tomography (PET) radiotracer, zirconium-89 (89Zr). The NPs maintained a small size of less than 100 nm, a relatively neutral charge and exhibited the ability to produce a cytotoxic effect on CSCs. There was a slight increase in killing with the aptamer-bound NPs compared to those without a targeting agent. This work has provided a potentially therapeutic option for GBM specific for CSC targeting and future in vivo biodistribution studies.