Hint2, a mitochondrial apoptotic sensitizer down-regulated in hepatocellular carcinoma

Martin, Juliette; Magnino, Fabrice; Schmidt, Karin; Piguet, Anne-Christine; Lee, Ju-Seog; Semela, David; St-Pierre, Marie V; Ziemiecki, Andrew; Cassio, Doris; Brenner, Charles; Thorgeirsson, Snorri S; Dufour, Jean-François (2006). Hint2, a mitochondrial apoptotic sensitizer down-regulated in hepatocellular carcinoma. Gastroenterology, 130(7), pp. 2179-88. Philadelphia, Pa.: Elsevier 10.1053/j.gastro.2006.03.004

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BACKGROUND ; AIMS: Hints, histidine triad nucleotide-binding proteins, are adenosine monophosphate-lysine hydrolases of uncertain biological function. Here we report the characterization of human Hint2. METHODS: Tissue distribution was determined by real-time quantitative polymerase chain reaction and immunoblotting, cellular localization by immunocytochemistry, and transfection with green fluorescent protein constructs. Enzymatic activities for protein kinase C and adenosine phosphoramidase in the presence of Hint2 were measured. HepG2 cell lines with Hint2 overexpressed or knocked down were established. Apoptosis was assessed by immunoblotting for caspases and by flow cytometry. Tumor growth was measured in SCID mice. Expression in human tumors was investigated by microarrays. RESULTS: Hint2 was predominantly expressed in liver and pancreas. Hint2 was localized in mitochondria. Hint2 hydrolyzed adenosine monophosphate linked to an amino group (AMP-pNA; k(cat):0.0223 s(-1); Km:128 micromol/L). Exposed to apoptotic stress, fewer HepG2 cells overexpressing Hint2 remained viable (32.2 +/- 0.6% vs 57.7 +/- 4.6%), and more cells displayed changes of the mitochondrial membrane potential (87.8 +/- 2.35 vs 49.7 +/- 1.6%) with more cleaved caspases than control cells. The opposite was observed in HepG2 cells with knockdown expression of Hint2. Subcutaneous injection of HepG2 cells overexpressing Hint2 in SCID mice resulted in smaller tumors (0.32 +/- 0.13 g vs 0.85 +/- 0.35 g). Microarray analyses revealed that HINT2 messenger RNA is downregulated in hepatocellular carcinomas (-0.42 +/- 0.58 log2 vs -0.11 +/- 0.28 log2). Low abundance of HINT2 messenger RNA was associated with poor survival. CONCLUSION: Hint2 defines a novel class of mitochondrial apoptotic sensitizers down-regulated in hepatocellular carcinoma.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > DCR Unit Tiefenau Hospital [discontinued] > Forschungsgruppe Biologie und Karzinogenese der Brustdrüse [discontinued] 04 Faculty of Medicine > Department of Gastro-intestinal, Liver and Lung Disorders (DMLL) > Clinic of Visceral Surgery and Medicine > Hepatology
UniBE Contributor:	Ziemiecki, Andrew, Dufour, Jean-François
ISSN:	0016-5085
ISBN:	16762638
Publisher:	Elsevier
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:45
Last Modified:	05 Dec 2022 14:14
Publisher DOI:	10.1053/j.gastro.2006.03.004
PubMed ID:	16762638
Web of Science ID:	000238207500023
URI:	https://boris.unibe.ch/id/eprint/18543 (FactScience: 735)