Cancer cells constantly adapt to oxidative phosphorylation (OXPHOS) suppression resulting from
hypoxia or mitochondria defects. Under the OXPHOS suppression,
AMP-activated protein kinase (AMPK) regulates global metabolism adjustments, but its activation has been found to be transient. Whether cells can maintain cellular
ATP homeostasis and survive beyond the transient AMPK activation is not known. Here, we study the bioenergetic adaptation to the OXPHOS inhibitor
oligomycin in a group of
cancer cells. We found that
oligomycin at 100 ng/ml completely inhibits OXPHOS activity in 1 h and induces various levels of glycolysis gains by 6 h, from which we calculate the bioenergetic organizations of
cancer cells. In glycolysis-dominant cells,
oligomycin does not induce much energy stress as measured by glycolysis acceleration,
ATP imbalance, AMPK activation, AMPK substrate
acetyl-CoA carboxylase phosphorylation at Ser(79), and cell growth inhibition. In OXPHOS-dependent LKB1 wild type cells,
oligomycin induces 5-8%
ATP drops and transient AMPK activation during the initial 1-2 h. After AMPK activation is completed,
oligomycin-induced increase of
acetyl-CoA carboxylase phosphorylation at Ser(79) is still detected, and cellular
ATP is back at preoligomycin treatment levels by sustained elevation of glycolysis. Cell growth, however, is inhibited without an increase in cell death and alteration in cell cycle distribution. In OXPHOS-dependent LKB1-null cells, no AMPK activation by
oligomycin is detected, yet cells still show a similar adaptation. We also demonstrate that the adaptation to
oligomycin does not invoke activation of
hypoxia-induced factor. Our data suggest that
cancer cells may grow and survive persistent OXPHOS suppression through an as yet unidentified regulatory mechanism.