Timeframe: 2016 – 2017
Goal: Develop new therapeutics for FLC
Principal Investigator: Sandy Simon, PhD
Investigator Collaboration: Barbara Lyons, PhD (New Mexico State University)
Study overview: The goal of this work was to identify potential therapeutic strategies to target FLC. The team identified three independent approaches to analyze based on their laboratory’s work showing that a single common DNA alteration is found in all fibrolamellar tumors leading to the DNAJB1-PRKACA fusion, and that this chimera is sufficient to cause fibrolamellar. The three sub-projects covered included:
- A high-throughput screen for molecules that directly block the chimera
- A screen to identify molecules that are directly phosphorylated by the chimera.
- An analysis of the structural dynamics of the chimera using a molecular dynamics simulation to identify sites on the chimera that would be appropriate for targeting therapeutics.
Key Findings: The study team purified the native and the chimera protein and observed the same level of kinase activity for both the proteins, which indicates that pan-kinase inhibitors may not work for FLC. Subsequently, they screened a library of approved bioactive compounds and identified a small molecule with some efficacy against the disease.
During the funding period, most progress was made against the third sub-project – characterizing the molecular dynamics of the chimera. Using molecular dynamics simulations and NMR, they found an ensemble of conformations of native and chimeric kinase. Because the conserved core of the wild-type enzyme and the chimeric fusion show little structural differences and the canonical function is not affected by the J-domain appendix, the presence of alternate conformations may create a way to target the chimera selectively. This opens up the possibility to develop novel small molecule inhibitors directed at the region of the fusion.
Results of the conformational analysis were published in Nature’s Scientific Reports, in January 2018. The text of that article – “Conformational Landscape of the PRKACA-DNAJB1 Chimeric Kinase, the Driver for Fibrolamellar Hepatocellular Carcinoma” – can be read here.