Suppression of proline-directed protein kinase F-A expression inhibits thegrowth of human chronic myeloid leukaemia cells

Initial studies revealed that proline-directed protein kinase F-A (PDPK F-A ) was overexpressed in various cancerous tissues relative to normal control s. 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 leukaemia cell growth by investigating the effects of partial inhibit ion of this kinase on the malignant phenotype of human chronic myeloid leuk aemia cells (K562). Cloning of PDPK F-A cDNA and its recombinant antisense expression vector and PDPK F-A-specific antibody were successfully develope d. Two stable antisense clones of K562 cells were subcloned which expressed 70% and 45% of PDPK F-A-respectively, compared with control-transfected cl one in both immunoprecipitate activity assay and immunoprecipitate analysis . In sharp contrast, these two antisense clones expressed no significant su ppression of any other related PDPK family members, indicating the specific ity of these two antisense clones. Moreover, these antisense clones proport ionally and potentially exhibited cell growth retardation, poor clonogenic growth in soft agar and loss of serum independence. The results demonstrate that specific antisense suppression of PDPK F-A is sufficient to interfere with the growth of K562 cells, indicating that PDPK F-A is essential for h uman chronic myeloid leukaemia cell growth. (C) 2000 Cancer Research Campai gn.