Cancer is associated with globally hypoacetylated
chromatin and considerable attention has recently been focused on epigenetic
therapies.
N-acetyl-L-aspartate (NAA), the primary storage form of
acetate in the brain, and
aspartoacylase (ASPA), the
enzyme responsible for NAA catalysis to generate
acetate and ultimately
acetyl-Coenzyme A for
histone acetylation, are reduced in
oligodendroglioma. The short chain
triglyceride glyceryl triacetate (GTA), which increases
histone acetylation and inhibits
histone deacetylase expression, has been safely used for
acetate supplementation in
Canavan disease, a leukodystrophy due to ASPA mutation. We demonstrate that GTA induces
cytostatic G0 growth arrest of
oligodendroglioma-derived cells in vitro, without affecting normal cells.
Sodium acetate, at doses comparable to that generated by complete GTA catalysis, but not
glycerol also promoted growth arrest, whereas long chain
triglycerides promoted cell growth. To begin to elucidate its mechanism of action, the effects of GTA on ASPA and
acetyl-CoA synthetase protein levels and differentiation of established human
oligodendroglioma cells (HOG and Hs683) and primary
tumor-derived
oligodendroglioma cells that exhibit some features of cancer stem cells (grade II OG33 and grade III OG35) relative to an oligodendrocyte progenitor line (Oli-Neu) were examined. The nuclear localization of ASPA and
acetyl-CoA synthetase-1 in untreated cells was regulated during the cell cycle. GTA-mediated growth arrest was not associated with apoptosis or differentiation, but increased expression of acetylated
proteins. Thus, GTA-mediated
acetate supplementation may provide a safe, novel epigenetic
therapy to reduce the growth of
oligodendroglioma cells without affecting normal neural stem or oligodendrocyte progenitor cell proliferation or differentiation.