We conducted the largest drug screen to date

We conducted the largest drug screen to date in HPV-positive cancers and identified Aurora kinase inhibitors as effective and understudied drugs in HNSCC and CESC. These drugs cause apoptosis and cell cycle arrest in vitro and decrease tumor size in vivo. This is the first published study to demonstrate that mutations in KMT2D (MLL2), which are common in many cancers, correlate with drug sensitivity in two independent data sets.
Funding source This work was supported by philanthropic contributions to The University of Texas MD Anderson HPV Moonshot (FMJ) and Oropharynx Discovery (JNM) Programs, and the National Institutes of Health/National Institute of Dental and Craniofacial Research (U01DE025181, JNM). Flow cytometry and bioinformatics were supported by the National Cancer Institute Support Grant P30CA016672. Cell line drug testing was also supported by Cancer Prevention Research Institute of Texas grant RP110532 (CCS).
Conflicts of interest
Acknowledgments
Auroras, serine–threonine kinases, have emerged as key regulators in the control of the cell cycle and mitosis. Mammalian genomes contain three genes encoding Aurora kinases, denoted Aurora A, B, and C. Each Aurora kinase shows a different subcellular location. Aurora A localizes to the centrosome and spindle poles, and is mainly related to centrosome function and spindle assembly. Aurora A may also be involved in cytokinesis, in accordance with its localization at the central spindle and midbody in the interleukin 1 receptor antagonist and telophase of mitosis. Aurora B is a member of the chromosome passenger complex, and localizes to centromeres during early mitosis, transfers to the midzone of the mitotic spindle and contractile ring during anaphase, and stays in the midbody during cytokinesis., Aurora C is specifically expressed in the testis and plays many roles in meiosis. Aurora C has been reported to be a chromosomal passenger protein with maximal expression in the G2/M phase of the cell cycle, and can complement the functions of Aurora B. Aurora kinases are strongly associated with human cancer. Accumulating evidence indicates that Aurora kinases are significantly overexpressed in a wide range of human cancer cell lines. Deregulation of Aurora kinase activity causes mitotic abnormalities, leading to genomic instability and ultimately tumorigenesis., Considering their importance in mitosis and association with tumorigenesis, Aurora kinases have been proposed as promising targets for cancer therapy., A growing number of Aurora kinase inhibitors are being developed, and many of these are in clinical trials. Recently, the pan-Aurora kinase inhibitor Danusertib (PHA-739358) and the selective Aurora B inhibitor Barasertib (AZD1152) have been in clinical trials for the treatment of leukemia, myeloma, and other solid tumors ()., Typical kinase inhibitors are classified by their binding mode (type I–IV). Type I kinase inhibitors work on the active form of enzymes in a competitive manner with ATP. In contrast, type II inhibitors interact with the inactive conformation of enzymes. In the case of type III kinase inhibitors, they bind in an allosteric pocket nearby active site, without any interaction with the ATP-binding pocket. Type IV kinase inhibitors placed to an allosteric site far from the ATP-binding pocket. There are two remarkable differences between the active and inactive conformations of the kinases. Firstly, an Asp residue (Asp218 in Aurora B) interacting with the gamma phosphate is reoriented in the inactive conformation by the DFG motif taking the ‘out’ position. The second important change is observed at a Glu residue (Glu125 in Aurora B), which is responsible for the construction of a salt bridge with β3 Lys (Lys106 in Aurora B), in the αC-helix., These conformational changes generate an additional allosteric site that opens favorable interactions for selectivity. In the present Letter, we report the discovery and identification of a novel series of 2-aminobenzoxazole analogs as type II kinase inhibitors. The representative structure of the targeted molecules is depicted in . Similar to many other type II kinase inhibitors, our aminobenzoxazole analogs consist of three parts; a hinge binder, a solvent accessible group, and DFG and allosteric site-interacting groups. Here, we examined their activities with respect to the inhibition of Aurora kinases, cell growth, and tumor growth using an ADP-Glo™ kinase assay, a cell-based assay, and PC-3 tumor xenograft model, respectively. We found that compound potentially inhibited Aurora B kinase activity and suppressed cell proliferation in the human cancer cell lines in vitro and the growth of PC-3 xenograft tumors in vivo. These observations suggest that compound is worthy of further study directed towards the identification of more potent and selective Aurora B kinase inhibitors as anticancer agents.