Downregulation of Epidermal Growth Factor Receptor Expression Contributes to 𝛼-TEA's Proapoptotic Effects in Human Ovarian Cancer Cell Lines

Figure 3

α-TEA decreased levels of the phosphorylated (active) form of Akt and its downstream substrate p-GSK3$\beta$. Overexpression of constitutively active Akt blocks $\alpha$-TEA’s ability to downregulate FLIP and survivin, while combinations of $\alpha$-TEA and chemical inhibitors of PI3K are better at inducing apoptosis and downregulating FLIP and survivin than single treatments. (a) Cells were treated with 20 $\mu$M (A2780S) or 40 $\mu$M (A2780/CP70R) of $\alpha$-TEA for 3, 6, 12, and 24 hours or vehicle control for 24 hours. Cell lysates from each treatment were analyzed by immunoblotting for pAkt, total Akt, pGSK3$\beta$ (Ser-9), and GSK3$\beta$. Numbers cited under lanes represent densitometric analyses of $\alpha$-TEA treated samples compared to vehicle control treated samples normalized for any lane load differences. (b) Immunoblotting analyses were conducted on whole cell lysates from A2780S and A2780/CP70R cells transiently transfected with HA-Myr-AKT2 plasmid, following treatment with $\alpha$-TEA at 20 or 40 $\mu$M, respectively, for 12 hours. (c) Cells were treated with two PI3K inhibitors, LY294002 (10 $\mu$M) or wortmannin (1 $\mu$M), and cultured with or without $\alpha$-TEA (10 or 20 $\mu$M for A2780S and A2780/CP70R cells, resp.) for 15 hours. At the end of the treatment period, cells were collected and total proteins were extracted for Western blot. All data are representative of a minimum of two independent experiments.

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