Effects of the Polo-like-kinase-1-inhibitor BI2536 in squamous cell carcinoma cell lines of the head and neck.

Inhibition of the Polo-like-kinase-1 (PLK1) has been shown to be effective in a number of solid tumor models. In this in vitro study, we examined the antitumor effect of BI2536, a small molecule inhibitor of PLK1, in squamous cell carcinoma of the head and neck (SCCHN) cell lines. Dose escalation studies were performed with nine SCCHN cell lines using BI2536. Growth inhibitory and proapoptotic effects were measured quantitatively using cytohistology and a Human Apoptosis Array Kit. BI2536 demonstrated a significant antiproliferative and apoptotic activity in all nine SCCHN cell lines investigated (p<0.009). Our results indicate that inhibition of PLK1 by BI2536 leads to an antiproliferative and apoptotic effect in SCCHN cell lines. In vivo and in the clinical setting, the application of BI2536 may support the antitumoral activity of conventional drugs that are in current use and could decrease the systemic toxicity of these drugs.