Abstract 3049: Development of novel survivin inhibitors to target mitotic machinery in cancers

Survivin, a member of the inhibitor of apoptosis (IAP) protein family has essential roles in cell division and inhibition of apoptosis. Over-expression of survivin is observed in most human cancers, but survivin expression is not detectable in non-proliferating normal adult tissues. In dividing cells, survivin is detected as an integral component of the chromosomal passenger complex (CPC). In the CPC, survivin is organized as a homodimer, associated with Aurora B-kinase and plays a critical role in the recruitment of a number of proteins to the kinetochore and centromere, which are essential for mitotic progression. Several clinical correlative studies in cancer patients have shown that elevated levels of survivin decreases overall survival and leads to resistance to radiation and chemotherapeutic treatments. Thus, disruption of functional survivin along its dimer interface is hypothesized to inhibit the proliferation of cancer cells by further sensitizing them to therapeutic agents and radiation. Recently, through HTS-NMR and AS/MS affinity based screenings, compound 1 (C1) was identified to bind to the dimerization interface of survivin monomers. Further development of this compound was accomplished by computational modeling of inhibitor interactions along the dimerization interface, which has lead to the design of a panel of promising compounds analogous to compound 1. Two of the most potent inhibitors included LLP3 and LLP9, which showed significant levels of activity between 50 and 100 nM. In proliferating human umbilical vein endothelial cells (HUVEC) as well as in prostate cancer cells (PC3) cells, the compounds caused a delay in mitotic progression and major mitotic defects. These cells expressed physiological levels of GFP-tagged survivin, which were used for visualization in automated fluorescent time-lapse videomicroscopy to investigate how the survivin dimerization inhibitors affected cell cycle progression. The same microscopy methods were used for understanding the specificity and activity of each respective compound. The investigation of cells treated with each of the compounds allowed for resolution of subcellular level effects on mitotic progression and CPC organization/movement during mitosis. The qualitative microscopy data was enumerated in order to quantify effects the compounds had on cells. The cells were enumerated in triplicate and tracked for changes in their proliferation, cell death, changes in ploidy, and other mitotic defects.