Differential effects of DMKG on the energy metabolism, autophagy, and
apoptosis of the parental and DOX-resistant liver cancer cell lines
Abstract
BACKGROUND AND PURPOSE In this study, we compared the different effect
of Dimethyl-2-ketoglutarate (DMKG) on energy metabolism, autophagy, and
apoptosis between parental and doxorubicin-resistant liver cancer cell
lines. EXPERIMENTAL APPROACH In the energy metabolism section, cell
viability, adenosine triphosphate (ATP) level, doxorubicin (DOX)
content, energy metabolism phenotype, and enzymes expression were
measured. In the autophagy part, autophagy vesicles were observed,
enzymes expression and cell viability were detected. Apoptosis rate and
expression of enzymes were detected in the apoptosis part. KEY RESULTS
DMKG can directly act on ATP synthase and prolyl hydroxylase, affecting
the cellular oxidative phosphorylation and glycolysis levels,
respectively, in both SMMC-7721 and SMMC-7721/DOX cells. However, its
practical effects depend on the function of the mitochondrial
malate-aspartate shuttle. Furthermore, ATP-reduced cell autophagy had
partial anti-apoptotic effects in SMMC-7721 cells, which is an important
reason for the weak inhibition of cell viability observed at low doses
of DMKG. In contrast, DMKG showed no significant effect on autophagy but
a high cell death rate in SMMC-7721/DOX cells. Induced high expression
levels of p-AMPK, p-mTOR, and Bcl-2 could inhibit DMKG-induced apoptosis
in SMMC-7721 cells. However, activation of Caspase-3 was the most
important molecular effect that was observed in relation to the
DMKG-induced apoptosis in SMMC-7721/DOX cells. CONCLUSIONS AND
IMPLICATIONS These results suggest that inhibition of energy metabolism
can reduce the effects of autophagy in DOX resistant cells, which could
improve the therapeutic outcomes and reverse the resistance to
chemotherapeutic drugs. This article provides a new idea and method for
reversing tumor resistance.