Biomedical Sciences ETDs

Publication Date

Spring 1-31-2018

Abstract

Vacuolar ATPase (V-ATPase) is responsible for maintaining the acidic pH of the endomembrane system in eukaryotic cells. V-ATPase active transport of protons generates the differential luminal pH in lysosomes, endosomes, and the Golgi. In addition to intracellular V-ATPase, cancer cells have V-ATPase at the plasma membrane. Plasmalemmal V-ATPase acidifies the extracellular milieu and enhances cell motility and invasion, evidence that V-ATPase contributes to tumorigenic phenotypes. We studied V-ATPase cellular functions in prostate cancer (PCa), the most commonly diagnosed cancer for men in the United States. V-ATPase inhibitors decreased invasion and migration of PCa cells. In aggressive PCa cell lines, C4-2B and PC3, V-ATPase was detected in plasma membrane enriched extracts and near the leading edge of migrating cells, respectively. V-ATPase was very abundant in the Golgi and clathrin-coated vesicles (CCV) of all the cell lines studied (LAPC4, LNCaP, C4-2B and PC3). V-ATPase inhibition increased the endo-lysosomal pH and altered F-actin organization and membrane traffic. Accrued cytosolic vesicles included CCV, recycling endosomes, and secretory vesicles. Prostate Specific Antigen (PSA) accumulated in the cytosol and its secretion of was reduced. PSA mRNA expression was reduced as well. The androgen receptor (AR) that controls PSA transcription was inhibited and AR protein and mRNA reduced by 50% or more. Moreover, V-ATPase inhibition increased cellular levels of the subunit α of hypoxia inducible factor 1 (HIF-1α), a transcription factor that regulates tumorigenesis. V-ATPase-dependent HIF-1α accumulation repressed AR expression that was rescued by iron in LNCaP and LAPC4 cells. Thus, V-ATPase-dependent pH and iron homeostasis can be altered to target androgen-AR signaling to inhibits cell proliferation in prostate tumors.

Keywords

V-ATPase, Prostate Cancer, Androgen Receptor, concanamycin, HIF-1, pH

Document Type

Dissertation

Language

English

Degree Name

Biomedical Sciences

Level of Degree

Doctoral

Department Name

Biomedical Sciences Graduate Program

First Committee Member (Chair)

Karlett J. Parra, Ph.D.

Second Committee Member

Rebecca S. Hartley, Ph.D.

Third Committee Member

Laurie G. Hudson, Ph.D.

Fourth Committee Member

Todd Thompson, Ph.D.

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