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04272021 FINAL_BG dissertation.pdf (4.61 MB)

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Role of the tumor microenvironment on mechanosensitive TRPV4 channels and tumor angiogenesis

Guarino, Brianna D
http://orcid.org/0000-0001-5824-1139
http://rave.ohiolink.edu/etdc/view?acc_num=ne2mh1619702863516646

Abstract Details

2021, Doctor of Philosophy, Northeast Ohio Medical University, Integrated Pharmaceutical Medicine.
Angiogenesis, the formation of new blood vessels from existing vasculature is an important physiological function. However, abnormal vessel formation (tumor angiogenesis) is one of the hallmarks of cancerous tumor development. The hyperpermeability and disorganized nature of the tumor vasculature act as a barrier to effective drug delivery. Traditional anti-angiogenic drugs, aimed to inhibit vascular endothelial growth factor (VEGF), have gained much attention as a cancer therapy, however, they are met with varying clinical problems, including acquired drug resistance. Therefore, it is crucial to identify alternative approaches, such as vascular normalization, to overcome the complications that arise from tumor angiogenesis. The goal of vascular normalization is to correct the abnormal characteristics observed in the tumor vasculature, with the ultimate intention being enhanced drug delivery and decreased metastasis. Previously, our lab identified TRPV4, a mechanosensitive ion channel, as a target of vascular normalization. We found that the functional expression of TRPV4 was downregulated in tumor endothelial cells (TEC), and that activation of these channels normalized the tumor vasculature and improved cancer therapy. However, the molecular mechanisms involved in TRPV4 downregulation in tumor endothelial cells are unknown. The first aim of this dissertation was to determine if and how the tumor microenvironment transforms normal endothelial cells into a tumor endothelial cell-like phenotype through the downregulation of TRPV4 channels. Here, we found that tumor cell conditioned media (TCM) transforms normal human endothelial cells into tumor endothelial-like cells via the downregulation of TRPV4 channels. Further, we showed that tumor-derived extracellular vesicles (t-EVs) isolated from TCM induces abnormal angiogenesis in vitro. The second aim of this dissertation was to investigate the role of t-EVs on TRPV4 downregulation and abnormal angiogenesis independent of tumors in vivo. Our data show that TRPV4 functional activity was indeed decreased in ECs after t-EV treatment, with concomitant disappearance of perinuclear VEGFR2. Additionally, we show that treatment with a Rho kinase inhibitor was able to restore t-EV-induced abnormal tube formation by ECs in vitro. Importantly, t-EVs induced abnormal angiogenesis in Matrigel plugs in WT mice, as evidenced by decreased pericyte coverage and increased VEGFR2 expression. Finally, the third aim of this dissertation was to determine if the inhibition of EVs normalizes the tumor vasculature. Our results revealed decreased vascular density, increased pericyte coverage, increased tumor growth, and decreased metastatic foci in syngeneic LLC tumor bearing mice treated with an exosome inhibitor, GW4869. Mechanistically, we found that TRPV4 mRNA showed no difference between t-EV-treated or control ECs. However, western blotting revealed significantly decreased TRPV4 protein expression in t-EV-treated ECs, indicating that t-EVs downregulate TRPV4 expression post-translationally. Taken together, our data suggest that t-EVs transform normal endothelial cells into tumor endothelial-like cells via the downregulation of TRPV4 channels, leading to abnormal angiogenesis, and that the targeting of EV formation or TRPV4 in tumors may induce vascular normalization and improve cancer therapy.
Charles Thodeti, PhD (Advisor)
Yin Liya , MD, PhD (Committee Member)
Kasumov Takhar , PhD (Committee Member)
Dong Feng , MD, PhD (Committee Member)
Smith Matthew , PhD (Committee Member)
123 p.
Biomedical Research; Molecular Biology; Physiology
Angiogenesis; TRPV4; extracellular vesicles, tumor, endothelial cell

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Citations

  • Guarino, B. D. (2021). Role of the tumor microenvironment on mechanosensitive TRPV4 channels and tumor angiogenesis [Doctoral dissertation, Northeast Ohio Medical University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ne2mh1619702863516646

    APA Style (7th edition)

  • Guarino, Brianna. Role of the tumor microenvironment on mechanosensitive TRPV4 channels and tumor angiogenesis . 2021. Northeast Ohio Medical University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ne2mh1619702863516646.

    MLA Style (8th edition)

  • Guarino, Brianna. "Role of the tumor microenvironment on mechanosensitive TRPV4 channels and tumor angiogenesis ." Doctoral dissertation, Northeast Ohio Medical University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ne2mh1619702863516646

    Chicago Manual of Style (17th edition)

ne2mh1619702863516646
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© 2021, all rights reserved.
This open access ETD is published by NEOMED Integrated Pharmaceutical Medicine and OhioLINK.