Molecular and metabolic consequences following E6 transfection in an isogenic ovarian cell line (A2780) pair

To examine molecular and metabolic consequences of HPV-16 viral- protein E6, which targets p53 for degradation, in A2780 (ovarian cancer) cells.

Isogenic derivatives of A2780 cells, with empty-vector (E6-) or E6 (E6+) transfection, were cultured. Intracellular metabolites, fatty acids, and the flux of glutamine, glucose, alanine and lactate in proliferation (Day 2) and confluence (Day 4) were determined using MRS. Western blotting confirmed p53 status, protein expressions related to AKT, ERK and mTOR signalling, and phospholipid metabolism.

Growth rate was slower in E6+ cells compared with E6-, resulting in reduced glycolysis, amino acid uptake and fatty acid synthesis. Glutamine metabolism, glycerophosphocholine (GPC), and protein expressions of cytosolic PLA2 (cPLA2) and p-cPLA2 increased in E6+ cells. Despite decreased ERK and AKT signalling, expression of S6RP and p-S6RP downstream of mTOR remained unaffected in E6+ cells. E6+ cells were more invasive and migrate faster than the E6- cells.

E6+ had slower growth than E6- cells with reduced metabolism, but E6+ cells maintained cellular homeostasis through glutamine metabolism when compared with E6- at Day 2. The ability to migrate and form larger colonies may provide the E6+ cells with a growth advantage.