title: Membrane potential differences and GABAA receptor expression in hepatic tumor and non-tumor stem cells.
abstract: The ability to differentiate tumor initiating stem cells (TISCs) from healthy, normal stem cells (NSCs) could have important diagnostic and therapeutic implications for patients with hepatocellular carcinoma (HCC). The aim of this study was to document and compare cell membrane potentials (PDs) and GABAA receptor subunit expression in hepatic TISCs and NSCs. PD values were determined in CD133(+) Huh-7 TISCs and CD133(+) WBF344 NSCs by single channel microelectrode impalement. GABAA receptor subunit expression was documented using immunohistochemistry (IH) in both cell lines as well as surgically resected HCC and healthy liver tissues. TISCs were significantly depolarized compared with NSCs (-4.0 ± 1.8 versus -11.0 ± 2.4 mV, respectively; p < 0.05). GABAA α6 subunit expression was either absent or markedly attenuated, while γ3 subunit expression was abundant in TISCs and HCC compared with NSCs and healthy liver tissues. Exposure to the GABAA receptor agonist muscimol caused hyperpolarization of TISCs (Δ -4.4 ± 1.1) but depolarization of NSCs (Δ + 5.2 ± 2.3) and attenuation of TISC proliferative activity. We conclude that TISCs and NSCs have significantly different cell membrane potentials and these differences are associated with differences in GABAA receptor subunit expression.
authors.affiliation: a Section of Hepatology, Department of Medicine, University of Manitoba, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada.
authors.forename: Wendy
authors.initials: W
authors.lastname: Bautista
authors.forename: Victor
authors.initials: V
authors.lastname: Perez-Alvarez
authors.forename: Frank
authors.initials: F
authors.lastname: Burczynski
authors.forename: Afshin
authors.initials: A
authors.lastname: Raouf
authors.forename: Thomas
authors.initials: T
authors.lastname: Klonisch
authors.forename: Gerald
authors.initials: G
authors.lastname: Minuk
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000097:blood / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018755:GABA Agonists / Q000494:pharmacology; D006023:Glycoproteins / Q000097:blood / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D008564:Membrane Potentials; D009118:Muscimol / Q000494:pharmacology; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000502:physiology*; D010455:Peptides / Q000097:blood / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism*
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D018755:GABA Agonists; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D021122:Protein Subunits; D011963:Receptors, GABA-A; D009118:Muscimol