Butyrate and its analogues have long been investigated as potential chemotherapeutic agents. Our previous structure-activity relationship studies of
butyrate analogues revealed that
4-benzoylbutyrate had comparable in vitro effects to
butyrate when used to treat HT29 and HCT116
colorectal cancer cell lines. The aim of this study was to identify potential mechanisms associated with the antitumorigenic effects of
4-benzoylbutyrate. In this study,
butyrate,
3-hydroxybutyrate and
4-benzoylbutyrate were also investigated for their effects on
histone deacetylase (HDAC) activity and
histone H4 acetylation in HT29 and HCT116 cells. The
biological effects of these analogues on HT29 cells were further investigated using quantitative proteomics to determine the
proteins potentially involved in their apoptotic and antiproliferative effects. Because
3-hydroxybutyrate had minimal to no effect on apoptosis, proliferation or HDAC activity, this analogue was used to identify differentially expressed
proteins that were potentially specific to the apoptotic effects of
butyrate and/or
4-benzoylbutyrate.
Butyrate treatment inhibited HDAC activity and induced H4 acetylation.
4-Benzoylbutyrate inhibited HDAC activity but failed to enhance H4 acetylation. Proteomic analysis revealed 20
proteins whose levels were similarly altered by both
butyrate and
4-benzoylbutyrate.
Proteins that showed common patterns of differential regulation in the presence of either
butyrate or
4-benzoylbutyrate included c-Myc transcriptional targets,
proteins involved in ER homeostasis, signal transduction pathways and cell energy metabolism. Although an additional 23
proteins were altered by
4-benzoylbutyrate uniquely, further work is required to understand the mechanisms involved in its apoptotic effects.