Abstract

Background: Therapies targeting altered activity of pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC) have been proposed for hepatomas. However, the activities of these pathways in hepatomas in vivo have not been distinguished. Here we examined pyruvate entry into the tricarboxylic acid (TCA) cycle through PDH versus PC in vivo using hepatoma-bearing rats. Methods: Hepatoma-bearing rats were generated by intrahepatic injection of H4IIE cells. Metabolism of 13C-labeled glycerol, a physiological substrate for both gluconeogenesis and energy production, was measured with 13C NMR analysis. The concentration of key metabolites and the expression of relevant enzymes were measured in hepatoma, surrounding liver, and normal liver. Results: In orthotopic hepatomas, pyruvate entry into the TCA cycle occurred exclusively through PDH and the excess PDH activity compared to normal liver was attributed to downregulated pyruvate dehydrogenase kinase (PDK) 2/4. However, pyruvate carboxylation via PC and gluconeogenesis were minimal, which was linked to downregulated forkhead box O1 (FoxO1) by Akt activity. In contrast to many studies of cancer metabolism, lactate production in hepatomas was not increased which corresponded to reduced expression of lactate dehydrogenase. The production of serine and glycine in hepatomas was enhanced, but glycine decarboxylase was downregulated. Conclusions: The combination of [U-13C3]glycerol and NMR analysis enabled investigation of multiple biochemical processes in hepatomas and surrounding liver. We demonstrated active PDH and other related metabolic alterations in orthotopic hepatomas that differed substantially not only from the host organ but also from many earlier studies with cancer cells.

Original languageEnglish (US)
Article number153993
JournalMetabolism: clinical and experimental
Volume101
DOIs
StatePublished - Dec 2019

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Gluconeogenesis
Pyruvic Acid
Hepatocellular Carcinoma
Oxidoreductases
Pyruvate Carboxylase
Citric Acid Cycle
Down-Regulation
Liver
Glycerol
Glycine Dehydrogenase (Decarboxylating)
Biochemical Phenomena
L-Lactate Dehydrogenase
Glycine
Serine
Lactic Acid
Neoplasms
Injections

Keywords

  • Cancer metabolism
  • Glycerol
  • Hepatocellular carcinoma
  • Pyruvate carboxylase
  • Pyruvate dehydrogenase
  • Tricarboxylic acid cycle

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

Cite this

@article{4335f647c7f242c6aa22c58c8a91ce0e,
title = "Active pyruvate dehydrogenase and impaired gluconeogenesis in orthotopic hepatomas of rats",
abstract = "Background: Therapies targeting altered activity of pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC) have been proposed for hepatomas. However, the activities of these pathways in hepatomas in vivo have not been distinguished. Here we examined pyruvate entry into the tricarboxylic acid (TCA) cycle through PDH versus PC in vivo using hepatoma-bearing rats. Methods: Hepatoma-bearing rats were generated by intrahepatic injection of H4IIE cells. Metabolism of 13C-labeled glycerol, a physiological substrate for both gluconeogenesis and energy production, was measured with 13C NMR analysis. The concentration of key metabolites and the expression of relevant enzymes were measured in hepatoma, surrounding liver, and normal liver. Results: In orthotopic hepatomas, pyruvate entry into the TCA cycle occurred exclusively through PDH and the excess PDH activity compared to normal liver was attributed to downregulated pyruvate dehydrogenase kinase (PDK) 2/4. However, pyruvate carboxylation via PC and gluconeogenesis were minimal, which was linked to downregulated forkhead box O1 (FoxO1) by Akt activity. In contrast to many studies of cancer metabolism, lactate production in hepatomas was not increased which corresponded to reduced expression of lactate dehydrogenase. The production of serine and glycine in hepatomas was enhanced, but glycine decarboxylase was downregulated. Conclusions: The combination of [U-13C3]glycerol and NMR analysis enabled investigation of multiple biochemical processes in hepatomas and surrounding liver. We demonstrated active PDH and other related metabolic alterations in orthotopic hepatomas that differed substantially not only from the host organ but also from many earlier studies with cancer cells.",
keywords = "Cancer metabolism, Glycerol, Hepatocellular carcinoma, Pyruvate carboxylase, Pyruvate dehydrogenase, Tricarboxylic acid cycle",
author = "Lee, {Min Hee} and DeBerardinis, {Ralph J.} and Xiaodong Wen and Corbin, {Ian R.} and Sherry, {A. Dean} and Malloy, {Craig R.} and Jin, {Eunsook S.}",
year = "2019",
month = "12",
doi = "10.1016/j.metabol.2019.153993",
language = "English (US)",
volume = "101",
journal = "Metabolism: Clinical and Experimental",
issn = "0026-0495",
publisher = "W.B. Saunders Ltd",

}

TY - JOUR

T1 - Active pyruvate dehydrogenase and impaired gluconeogenesis in orthotopic hepatomas of rats

AU - Lee, Min Hee

AU - DeBerardinis, Ralph J.

AU - Wen, Xiaodong

AU - Corbin, Ian R.

AU - Sherry, A. Dean

AU - Malloy, Craig R.

AU - Jin, Eunsook S.

PY - 2019/12

Y1 - 2019/12

N2 - Background: Therapies targeting altered activity of pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC) have been proposed for hepatomas. However, the activities of these pathways in hepatomas in vivo have not been distinguished. Here we examined pyruvate entry into the tricarboxylic acid (TCA) cycle through PDH versus PC in vivo using hepatoma-bearing rats. Methods: Hepatoma-bearing rats were generated by intrahepatic injection of H4IIE cells. Metabolism of 13C-labeled glycerol, a physiological substrate for both gluconeogenesis and energy production, was measured with 13C NMR analysis. The concentration of key metabolites and the expression of relevant enzymes were measured in hepatoma, surrounding liver, and normal liver. Results: In orthotopic hepatomas, pyruvate entry into the TCA cycle occurred exclusively through PDH and the excess PDH activity compared to normal liver was attributed to downregulated pyruvate dehydrogenase kinase (PDK) 2/4. However, pyruvate carboxylation via PC and gluconeogenesis were minimal, which was linked to downregulated forkhead box O1 (FoxO1) by Akt activity. In contrast to many studies of cancer metabolism, lactate production in hepatomas was not increased which corresponded to reduced expression of lactate dehydrogenase. The production of serine and glycine in hepatomas was enhanced, but glycine decarboxylase was downregulated. Conclusions: The combination of [U-13C3]glycerol and NMR analysis enabled investigation of multiple biochemical processes in hepatomas and surrounding liver. We demonstrated active PDH and other related metabolic alterations in orthotopic hepatomas that differed substantially not only from the host organ but also from many earlier studies with cancer cells.

AB - Background: Therapies targeting altered activity of pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC) have been proposed for hepatomas. However, the activities of these pathways in hepatomas in vivo have not been distinguished. Here we examined pyruvate entry into the tricarboxylic acid (TCA) cycle through PDH versus PC in vivo using hepatoma-bearing rats. Methods: Hepatoma-bearing rats were generated by intrahepatic injection of H4IIE cells. Metabolism of 13C-labeled glycerol, a physiological substrate for both gluconeogenesis and energy production, was measured with 13C NMR analysis. The concentration of key metabolites and the expression of relevant enzymes were measured in hepatoma, surrounding liver, and normal liver. Results: In orthotopic hepatomas, pyruvate entry into the TCA cycle occurred exclusively through PDH and the excess PDH activity compared to normal liver was attributed to downregulated pyruvate dehydrogenase kinase (PDK) 2/4. However, pyruvate carboxylation via PC and gluconeogenesis were minimal, which was linked to downregulated forkhead box O1 (FoxO1) by Akt activity. In contrast to many studies of cancer metabolism, lactate production in hepatomas was not increased which corresponded to reduced expression of lactate dehydrogenase. The production of serine and glycine in hepatomas was enhanced, but glycine decarboxylase was downregulated. Conclusions: The combination of [U-13C3]glycerol and NMR analysis enabled investigation of multiple biochemical processes in hepatomas and surrounding liver. We demonstrated active PDH and other related metabolic alterations in orthotopic hepatomas that differed substantially not only from the host organ but also from many earlier studies with cancer cells.

KW - Cancer metabolism

KW - Glycerol

KW - Hepatocellular carcinoma

KW - Pyruvate carboxylase

KW - Pyruvate dehydrogenase

KW - Tricarboxylic acid cycle

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UR - http://www.scopus.com/inward/citedby.url?scp=85074159822&partnerID=8YFLogxK

U2 - 10.1016/j.metabol.2019.153993

DO - 10.1016/j.metabol.2019.153993

M3 - Article

C2 - 31672442

AN - SCOPUS:85074159822

VL - 101

JO - Metabolism: Clinical and Experimental

JF - Metabolism: Clinical and Experimental

SN - 0026-0495

M1 - 153993

ER -