Prevention of hepatocarcinogenesis and increased susceptibility to acetaminophen-induced liver failure in transaldolase-deficient mice by N-acetylcysteine
Robert Hanczko, David R. Fernandez, Edward Doherty, Yueming Qian, Gyorgy Vas, Brian Niland, Tiffany Telarico, Adinoyi Garba, Sanjay Banerjee, Frank A. Middleton, Donna Barrett, Maureen Barcza, Katalin Banki, Steve K. Landas, Andras Perl
Robert Hanczko, David R. Fernandez, Edward Doherty, Yueming Qian, Gyorgy Vas, Brian Niland, Tiffany Telarico, Adinoyi Garba, Sanjay Banerjee, Frank A. Middleton, Donna Barrett, Maureen Barcza, Katalin Banki, Steve K. Landas, Andras Perl
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Research Article Gastroenterology

Prevention of hepatocarcinogenesis and increased susceptibility to acetaminophen-induced liver failure in transaldolase-deficient mice by N-acetylcysteine

Abstract

Although oxidative stress has been implicated in acute acetaminophen-induced liver failure and in chronic liver cirrhosis and hepatocellular carcinoma (HCC), no common underlying metabolic pathway has been identified. Recent case reports suggest a link between the pentose phosphate pathway (PPP) enzyme transaldolase (TAL; encoded by TALDO1) and liver failure in children. Here, we show that Taldo1–/– and Taldo1+/– mice spontaneously developed HCC, and Taldo1–/– mice had increased susceptibility to acetaminophen-induced liver failure. Oxidative stress in Taldo1–/– livers was characterized by the accumulation of sedoheptulose 7-phosphate, failure to recycle ribose 5-phosphate for the oxidative PPP, depleted NADPH and glutathione levels, and increased production of lipid hydroperoxides. Furthermore, we found evidence of hepatic mitochondrial dysfunction, as indicated by loss of transmembrane potential, diminished mitochondrial mass, and reduced ATP/ADP ratio. Reduced β-catenin phosphorylation and enhanced c-Jun expression in Taldo1–/– livers reflected adaptation to oxidative stress. Taldo1–/– hepatocytes were resistant to CD95/Fas-mediated apoptosis in vitro and in vivo. Remarkably, lifelong administration of the potent antioxidant N-acetylcysteine (NAC) prevented acetaminophen-induced liver failure, restored Fas-dependent hepatocyte apoptosis, and blocked hepatocarcinogenesis in Taldo1–/– mice. These data reveal a protective role for the TAL-mediated branch of the PPP against hepatocarcinogenesis and identify NAC as a promising treatment for liver disease in TAL deficiency.

Authors

Robert Hanczko, David R. Fernandez, Edward Doherty, Yueming Qian, Gyorgy Vas, Brian Niland, Tiffany Telarico, Adinoyi Garba, Sanjay Banerjee, Frank A. Middleton, Donna Barrett, Maureen Barcza, Katalin Banki, Steve K. Landas, Andras Perl

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Figure 8

Increased susceptibility of Taldo1–/– mice to liver failure induced by APAP.

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Increased susceptibility of Taldo1–/– mice to liver failure induced by A...
(A) Survival of Taldo1+/+ (n = 26), Taldo1+/– (n = 28), and Taldo1–/– littermates (n = 23) injected with 800 mg/kg APAP. Log-rank test showed reduced survival of Taldo1–/– compared with Taldo1+/+ mice (P = 0.027). No significant difference was observed between the Taldo1+/– and Taldo1+/+ groups. (B) H&E-stained liver sections obtained 6 hours after APAP injection. Hemorrhagic necrosis, characterized by hepatocyte vacuolization and extravasation of erythrocytes, was enhanced in Taldo1–/– liver. Original magnification, ×100. (C) Western blot detection of 46- and 54-kDa JNK and their state of phosphorylation (p46 and p54 JNK) in APAP-injected and untreated control mice. Numbers below blots show p-JNK/JNK levels, which were determined relative to actin and normalized to untreated Taldo1+/+ protein lysates, set as 1.0. (D) Assessment of JNK activity by in vitro phosphorylation of GST–c-Jun1–89 fusion protein in APAP-treated liver. TAL, c-Jun, and actin levels were detected by Western blot of liver cell lysates. In vitro phosphorylation of GST–c-Jun was detected by Western blot analysis using anti–phospho–c-JunSer63 antibody. (E) Effect of SP600125 on APAP-induced activation of JNK. Littermate 12-week-old mice were pretreated with SP600125 or DMSO control as described in Methods 1 hour prior to APAP exposure. Numbers below blots show p-JNK/JNK levels 3 hours after APAP treatment; values were determined relative to actin and normalized to untreated Taldo1+/+ protein lysates, set as 1.0.