The role of Mcl-1 in the response of human colorectal cancer cells to treatment with dichloroacetate
Dichloroacetate (DCA) it a metabolic reprogramming agent that is used to target the unique metabolism of cancer cells, but is not always effective in colorectal cancer cells. In HCT116 cells, DCA was unable to induce apoptosis, but did decrease proliferation when compared to untreated cells. A decrease in full length Mcl-1 protein expression 7 hours following DCA treatment did not correspond with changes in mRNA production or changes in expression of inhibitory binding partners, but may be due to altered proteasomal degradation. Similar reduction in levels of a lower molecular weight Mcl-1 band occurred, which did not result from alternative splicing or from caspase-mediated cleavage. Mcl-1 showed primarily nuclear localization within the cell, and expression changes in full-length Mcl-1 were seen in nuclear lysate but not cytoplasmic lysate after 7 hours of DCA treatment. Changes in nuclear Mcl-1 expression did not correspond with cell cycle arrest or progression. These results suggest that proteasomal degradation of Mcl-1 may be altered following treatment with DCA, and this change may be associated with decreased proliferation, independent of cell cycle arrest. This may indicate a novel role of nuclear Mcl-1 in response of colorectal cancer to DCA exposure.