The cell penetrating ability of the proapoptotic peptide, KLAKLAKKLAKLAK fused to the N-terminal protein transduction domain of translationally controlled tumor protein, MIIYRDLISH.

We show here, that the proapoptotic peptide, KLAKLAKKLAKLAK (KLA), which by itself does not penetrate cell membranes, can do so when fused to a protein transduction domain derived from NH(2)-terminus of translationally controlled tumor protein (TCTP-PTD, MIIYRDLISH). Once inside the cell, the conjugated KLA exerts its proapoptotic activity to inhibit tumor growth. We evaluated the cellular uptake of KLA fused to TCTP-PTD (hereafter called TCTP-KLA) and its effect on cancer cell viability. The IC(50) of TCTP-KLA was between 7 and 10 μmol/L. We also evaluated its anti-tumor activity in vivo by injecting it into xenografts of lung carcinoma in Balb/c nude mice. Tumor growth inhibition resulting from treatment with TCTP-KLA was better than that of TAT-KLA. These results suggest that TCTP-KLA can be applied to design cancer therapeutics.