Suppression of proline-directed protein kinase F(A) systemically inhibits the growth of human acute leukemia cells.

Initial studies revealed that proline-directed protein kinase F(A) (PDPK F(A)) was overexpressed in various cancerous tissues relative to normal controls. However, the functional role of overexpressed PDPK F(A) in cancer remains to be established. In this report, we explore the potential role of PDPK F(A) in leukemia cell growth by investigating the effects of partial inhibition of this kinase on human acute promyelocytic leukemia (HL-60) and acute lymphoblastic leukemia (Jurkat) cells. Cloning of PDPK F(A) cDNA and its recombinant antisense expression vector and antibody were successfully developed. Several stable antisense clones of HL-60 and Jurkat cells were subcloned, which expressed a low level of PDPK F(A) when compared with the control-transfected clone in immunoblot analysis. Moreover, these antisense clones potently inhibited cell growth, clonogenic growth in soft agar and serum-independent growth. The results taken together demonstrate that suppression of PDPK F(A) is able to interfere with the growth of HL-60 and Jurkat cells, suggesting an essential role of this PDPK in human acute leukemia cell growth.