Developing ribosome biogenesis inhibitors for the prevention of cancer

Tumor formation and cancer cell proliferation depend on enhanced ribosome biogenesis and protein synthesis. Ribosomes are the molecular machines responsible for protein production within cells. Emerging data indicates that inhibition of ribosome formation and function can prevent cancers from forming in certain contexts. For example, liver disease predisposes patients for liver cancer, including hepatocellular carcinoma, and this transition is marked by enhanced ribosome biogenesis. Inhibition of ribosome function prevents liver tumor formation in mouse models. Thus, additional compounds that attenuate ribosome production and activity may be able to prevent the formation of tumors. Unfortunately, previously available methods used to study ribosome biogenesis are laborious and not easily scalable. This has significantly hampered the development of new ribosome biogenesis inhibitors. To overcome this critical barrier, we have developed an innovative platform that we call ribo-SNAP, which allows us to assay the dynamics of ribosome biogenesis at single cell resolution in living cells. Using this platform, we have successfully completed pilot compound screens and identified new genes and small molecules that inhibit the protein synthesis capacity of cancer cells. In parallel, we have also developed a second novel assay called SidBait, which allows us to robustly and rapidly identify compound targets within cells. Using these approaches, we are in a unique position to identify and develop ribosome biogenesis inhibitors as effective anti-cancer agents. We now seek to expand our efforts to the larger NCI natural product library. The proposal is divided into UG3 and UH3 sections. Under Aim 1, we will further optimize the ribo-SNAP platform and conduct a small pilot screen of a subset of fractions from the SOOK natural product library. In Aim 2, we will use Sid Bait to identify the targets of compounds identified in the pilot screen or our ongoing screen of an independent 3SOK compound library. Experiments described under Aim 3 will directly test the extent to which ribosome biogenesis inhibitors can prevent liver tumor formation in mouse models. These three aims have clear milestones and we anticipate that the successful completion of the UG3 phase will allow the project to advance. During the UH3 phase, the large of screening will expand to the entire SOOK library under Aim 4. Sid Bait will be used in Aim 5 to begin to determine the mechanism of action of specific compounds. Finally, under Aim 6, mouse models will be used to test whether lead molecule prevent cancer progression. The successful completion of the entire project described in this proposal will provide an unparalleled collection of ribosome biogenesis inhibitors that can be further developed into novel therapeutics for the prevention of liver cancer.