Acetoacetate coenzyme A transferase activity in rat hepatomas

Area of Science:

• Biochemistry
• Oncology
• Metabolic research

Background:

• Succinyl-coenzyme A:acetoacetate CoA transferase (CoA transferase) initiates ketone body utilization in non-hepatic tissues.
• Understanding CoA transferase levels is crucial for metabolic studies in various physiological and pathological conditions.

Purpose of the Study:

• To investigate the presence and activity of CoA transferase in different rat liver conditions and transplantable hepatomas.
• To compare the biochemical and kinetic properties of CoA transferase from normal liver, tumor tissue, and skeletal muscle.

Main Methods:

• Assay of CoA transferase activity in normal, regenerating, neonatal, and tumor-bearing rat livers.
• Analysis of CoA transferase in a series of Morris hepatomas with varying growth rates.
• Biochemical characterization including size, kinetic parameters, and isoelectric focusing of CoA transferase from normal and hepatoma tissues.

Main Results:

• CoA transferase levels are very low in normal, host, and regenerating liver but significantly elevated in neonatal liver and hepatomas.
• A positive correlation exists between CoA transferase content and tumor growth rate in Morris hepatomas.
• The enzyme from fast-growing hepatoma (7288Ctc) shares biochemical similarities with that from skeletal muscle, including size, mechanism, kinetic parameters, and isoelectric point.

Conclusions:

• Faster-growing hepatomas possess substantial capacity for ketone body utilization.
• The biochemical properties of CoA transferase are conserved between highly proliferative tumors and differentiated non-hepatic tissues like skeletal muscle.