Discovery of a novel inhibitor of FOXO nuclear–cytoplasmic shuttling

The therapeutic manipulation of the nucleo-cytoplasmic shuttling of macromolecules has emerged as a promising approach to treat human diseases. In particular, the subcellular localization of tumor suppressors and oncogenic proteins is tightly regulated and essential for their function. FOXO transcription factors are involved in normal cell homeostasis and neoplasia, and they are regulated by multiple post-transcriptional modifications. In cancer research, the regulation of the FOXO factors is receiving increasing attention as their activation has been linked to cell-cycle arrest and apoptosis. Here, we used a high-throughput cellular-imaging assay that monitors the nuclear– cytoplasmic translocation of a GFP–FOXO3a fusion protein in tumor cells [1] to study activity of two newly synthetized compounds derived from aulosirazole [2-3]. Fluorescent signals upon treatment allow us to study the mechanisms that influence the intracellular localization of the FOXO family member FOXO3a. While both compounds are cytotoxic in a panel of cancer cell lines, 612 compound present activity in FoxRELOC assay. This activity is confirmed by confocal analyze of native FOXO3a nuclear accumulation after 612 compound treatment of wild type cells.