6AN (6-Aminonicotinamide)

Blocking the pentose phosphate pathway (PPP) by 6-AN significantly inhibits mES colony formation in the presence of a normal concentration of glucose. 6-AN treatment effectively inhibits AKT phosphorylation and activation of its downstream effector S6. 6-AN treatment has no effect on the ERK and PDK1 activities, suggesting an AKT-specific effect. 6-AN treatment inhibits cell growth.^[2]

PHLDA3 knockout blocks the effects of 6-AN, R5P or uridine on cell growth in vitro. Isogenic PHLDA3 WT and knockout HeLa cells are seeded in 96-well plates at a density of 1000 cells/well. After 48 h, the cells are treated with 6-AN (100 nM). Cell viability is detected by CCK-8 assays at indicated time points.

PTEN null human cancer cells and in vivo murine models are sensitive to 6-AN (anti-PPP, anti pentose phosphate pathway) treatments, suggesting the importance of the PPP in maintaining AKT activation even in the presence of a constitutively activated PI3K pathway. The treatment of TALL models with 6-AN significantly increases the Phlda3 mRNA and protein levels, accompanied by substantial decreases in the levels of P-AKT and P-S6 as well as the PPP metabolic intermediates.^[2]