title: Decreased hepatocyte membrane potential differences and GABAA-beta3 expression in human hepatocellular carcinoma.
abstract: To determine whether hepatocyte membrane potential differences (PDs) are depolarized in human HCC and whether depolarization is associated with changes in GABAA receptor expression, hepatocyte PDs and gamma-aminobutyric acid (GABA)A receptor messenger RNA (mRNA) and protein expression were documented in HCC tissues via microelectrode impalement, real-time reverse-transcriptase polymerase chain reaction, and Western blot analysis, respectively. HCC tissues were significantly depolarized (-19.8+/-1.3 versus -25.9+/-3.2 mV, respectively [P<0.05]), and GABAA-beta3 expression was down-regulated (GABAA-beta3 mRNA and protein expression in HCC; 5,693+/-1,385 and 0.29+/-0.11 versus 11,046+/-4,979 copies/100 mg RNA and 0.62+/-0.16 optical density in adjacent tumor tissues, respectively [P=0.002 and P<0.0001, respectively]) when compared with adjacent nontumor tissues. To determine the physiological relevance of the down-regulation, human malignant hepatocytes deficient in GABAA-beta3 receptor expression (Huh-7 cells) were transfected with GABAA-beta3 complementary DNA (cDNA) or vector alone and injected into nu/nu nude mice (n=16-17 group). Tumors developed after a mean (+/-SD) of 51+/-6 days (range: 41-60 days) in 7/16 (44%) mice injected with vector-transfected cells and 70+/-12 days (range: 59-86 days) in 4/17 (24%) mice injected with GABAA-beta3 cDNA-transfected cells (P<0.005).
  
  
  CONCLUSIONS
  The results of this study indicate that (1) human HCC tissues are depolarized compared with adjacent nontumor tissues, (2) hepatic GABAA-beta3 receptor expression is down-regulated in human HCC, and (3) restoration of GABAA-beta3 receptor expression results in attenuated in vivo tumor growth in nude mice.
authors.affiliation: Section of Hepatology, Department of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada. gminuk@cc.umanitoba.ca
authors.forename: Gerald Y
authors.initials: GY
authors.lastname: Minuk
authors.forename: Manna
authors.initials: M
authors.lastname: Zhang
authors.forename: Yuewen
authors.initials: Y
authors.lastname: Gong
authors.forename: Leonard
authors.initials: L
authors.lastname: Minuk
authors.forename: Hans
authors.initials: H
authors.lastname: Dienes
authors.forename: Norman
authors.initials: N
authors.lastname: Pettigrew
authors.forename: Michael
authors.initials: M
authors.lastname: Kew
authors.forename: Jeremy
authors.initials: J
authors.lastname: Lipschitz
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Sun
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology*; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D022781:Hepatocytes / Q000502:physiology*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology*; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: C546273:GABRB3 protein, human; C546270:Gabrb3 protein, mouse; D012333:RNA, Messenger; D011963:Receptors, GABA-A; D000254:Sodium-Potassium-Exchanging ATPase