Curcumin up-regulates Akt phosphorylation in MCF-7 cells
It is now well established that activation/inactivation of Akt is the key determinant in defining sensitivity to chemotherapeutic drugs. To confirm this we treated MCF-7 cells with 40 lM curcumin for different time periods, and the collected cell lysates were subjected to Western blot analysis for phospho-Akt. The result in Fig. 3A showed that curcumin increases the phosphorylation of Akt at Ser473 in a time dependant manner, without effecting total Akt expression.
Glycogen synthase kinase 3b, a downstream Akt substrate, mediates apoptosis in response to various stimuli. GSK3b is inhibited by Akt once it is phosphorylated by Akt on serine residue 9. As shown in Fig. 3B curcumin induced the phosphorylation of GSK3b at Ser9. Thus, Akt phosphorylation at Ser473 is correlating with phosphorylation of GSK3b at ser9.