Altered mitochondrial function and cholesterol synthesis influences protein synthesis in extended HepG2 spheroid cultures

Cultures of hepatocytes and HepG2 cells provide useful in vitro models of liver specific function. In this study, we investigated metabolic and biosynthetic function in 3-D HepG2 spheroid cultures, in particular to characterise changes on prolonged culture. We show that HepG2 cells cultured in spher...

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Bibliographic Details
Published in:Archives of biochemistry and biophysics 2004-12, Vol.432 (2), p.167-177
Main Authors: Damelin, Leonard H., Coward, Sam, Choudhury, Sarah F., Chalmers, Sherri-Ann, Cox, I. Jane, Robertson, Nicola J., Revial, Gilbert, Miles, Marianne, Tootle, Rosemary, Hodgson, Humphrey J.F., Selden, Clare
Format: Article
Language:English
Subjects:
3-D culture
Albumins - metabolism
Biosynthesis
Cell Culture Techniques - methods
Cell Respiration - drug effects
Cell Respiration - physiology
Cells, Cultured
Cholesterol
Cholesterol - biosynthesis
Environment
Glucose - metabolism
Hepatocytes - drug effects
Hepatocytes - physiology
HepG2
Lovastatin
Lovastatin - pharmacology
Membrane Potentials - drug effects
Membrane Potentials - physiology
Metabolism
Microspheres
Mitochondria, Liver - drug effects
Mitochondria, Liver - physiology
Mitochondrial function
Mitochondrial Proteins - metabolism
Oxygen - metabolism
Signal Transduction - physiology
Spheroids
Tissue Engineering - methods
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Summary:Cultures of hepatocytes and HepG2 cells provide useful in vitro models of liver specific function. In this study, we investigated metabolic and biosynthetic function in 3-D HepG2 spheroid cultures, in particular to characterise changes on prolonged culture. We show that HepG2 cells cultured in spheroids demonstrate a reduction in mitochondrial membrane potential and respiration following 10 days of culture. This coincides with a modest reduction in glycolysis but an increase in glucose uptake where increased glycogen synthesis occurs at the expense of the intracellular ATP pool. Lowered biosynthesis coincides with and is linked to mitochondrial functional decline since low glucose-adapted spheroids, which exhibit extended mitochondrial function, have stable biosynthetic activity during extended culture although biosynthetic function is lower. This indicates that glucose is required for biosynthetic output but sustained mitochondrial function is required for the maintenance of biosynthetic function. Furthermore, we show that cholesterol synthesis is markedly increased in spheroids cf. monolayer culture and that inhibition of cholesterol synthesis by lovastatin extends mitochondrial and biosynthetic function. Therefore, increased cholesterol synthesis and/or its derivatives contributes to mitochondrial functional decline in extended HepG2 spheroid cultures.
ISSN:0003-9861
1096-0384
DOI:10.1016/j.abb.2004.09.023