Identification of Akt-selective cytotoxic compounds that enhance cytotoxic responses to rapamycin.

We performed a high-throughput screen to identify compounds with a selective ability to induce apoptosis in Akt-expressing cells without disrupting Bcl-xL-dependent survival. Results showed that a screening strategy based on Alamar Blue underrepresented the viability of Bcl-xL-expressing cells relative to Akt-expressing cells, possibly due to metabolic differences between the two cell survival programs. Using an alternative screen based on plasma membrane integrity, we identified several compounds that target Akt-dependent survival without toxic effect to Bcl-xL-dependent survival. These compounds enhanced the cytotoxic potential of rapamycin, a chemotherapeutic that inhibits survival signaling downstream of Akt. The results demonstrate a screening method and the subsequent identification of two compounds with selective activity in counteracting Akt-dependent cell survival.