Astrocytoma is currently incurable due to its diffuse infiltration and the lack of effective therapies. We are developing a mouse model of spontaneous astrocytoma through mutation of Nf1 and p53. Both Nf1 and p53 have been shown to be mutated in sporadic human glioblastomas (GBM). In addition, p53 has been shown to be mutated in anaplastic astrocytomas, although NF1 has not yet been examined. In addition, Nf1 is associated with the disease neurofibromatosis type 1 (NF1), for which there are no cures and very few therapy options for treatment. The astrocytomas and GBM in the Nf1/p53 mutant mice show diffuse infiltration throughout the central nervous system and form secondary structures around neurons and blood vessels recapitulating the pathology seen in human astrocytomas. We are developing methods for using this model for testing experimental therapeutics. During fiscal year 2010 we developed our collaboration with the Molecular Targets Laboratory to use this assay for high-throughput screening of compound libraries available at NCI. We completed the screening of all of the chemically defined libraries available through the Molecular Targets Laboratory, and have begun screening crude natural product extracts. We have identified roughly 8 prefractionated natural product extracts with promising activity against brain tumor cells that we are pursuing further. Through these efforts we also identified the serotonin and PKA pathways as worthy of further study for the inhibition of brain tumors, work that will continue in a more focused way next fiscal year within project ZIA BC 010540. We have also continued our collaboration with a clinical NF group at Children's National Medical Center to take promising therapeutic leads for testing in our Nf1/p53 mouse model. In another collaboration with the Molecular Targets Laboratory, we are examining the effects of a natural compound, Schweinfurthin, on astrocytoma in vitro and in vivo. We have shown that Schweinfurthin inhibits multiple NF1-associated tumor types. This in vitro work was published this year in Molecular Cancer Therapeutics (Turbyville et al 2010) and we are continuing our efforts in vivo. We have tested additional Schweinfurthin analogues that may provide better stability in vivo and have developed a better formulation for in vivo testing. During fiscal year 2010, in collaboration with the Molecular Target Laboratory, the Center for Applied Preclinical Research, and the Laboratory of Proteomics and Analytical Technologies, we have developed a method to detect the compound in mouse tissues and body fluids and are currently examining the pharmokinetics of the compound in mice for the first time. This will allow us to establish the protocols needed to determine if this compound is effective against NF1 tumors in vivo.
