Abstract B218: Lentiviral shRNA screen of human kinases identifies PLK1 as a potential therapeutic target for osteosarcoma

Abstract

Abstract Induction of RNA interference in cancer cells has made possible high-throughput genome-wide loss-of-function studies using reverse genetic screening techniques. Kinases play an important role in the growth and survival of tumor cells. We aim to identify kinases that are vital to the survival of osteosarcoma cells and may be a key target in creating novel anticancer therapies. We describe an optimized systematic screen of known kinases using osteosarcoma cell lines (KHOS and U-2OS) and a lentiviral-based short hairpin RNA (shRNA) human kinase library. CellTiter 96® AQueous One Solution Cell Proliferation Assay was used to measure cell growth and survival. We identified several kinases, including human polo-like kinase (PLK1), which inhibit cell growth and induce apoptosis in osteosarcoma cells when knocked down. cDNA rescue and synthetic siRNA assays confirm that the observed phenotypic changes result from the loss of PLK1 gene expression. Furthermore, a small molecule inhibitor to PLK1 inhibited osteosarcoma cell growth and induced apoptosis. Western blot analysis confirmed that PLK1 is highly expressed and activated in several osteosarcoma cell lines as well as in resected tumor samples. Immunohistochemistry analysis showed that patients with high PLK1 tumor expression levels correlated with significantly shorter survival than patients with lower levels of tumor PLK1 expression. These results demonstrate the capability and feasibility of a high-throughput screen with a large collection of lentiviral kinases and its effectiveness in identifying potential drug targets. The development of more potent inhibitors that target PLK1 may open doors to a new range of anti-cancer strategies in osteosarcoma. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B218.