PLK1 as a potential drug target in cancer therapy

Polo-like kinase 1 (PLK1) has been shown to be involved in cell cycle progression of rapidly proliferating, nontransformed cells as well as tumor cells. In cancer, overexpression of PLK1 contributes to the malignant state by aberrant cell cycle regulation at the G2/M phase. We attempted to validate PLK1 function in cell-based assays using antisense oligonucleotide knockout approaches. Our own results and published findings of other groups have led to the conclusion that PLK1 is a logical point for pharmacological intervention. HTS campaigns performed against the recombinant PLIK1-protein led to the identification of two PLK1 inhibitory scaffolds, one containing a 7-azapteridine ring system, the other a fused tetracyclic ketone system. These compounds showed low micromolar antiproliferative activity towards SW620, a human colon cancer cell line, most likely through cell cycle arrest at the G2/M phase. Our data suggest that PLK1 may serve as a target for discovering small molecule anticancer agents. (C) 2004 Wiley-Liss, Inc.