TIC10 anti-tumor effect through regulation of Foxo3a and TRAIL

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Project Summary The potency and safety of TRAIL has prompted clinical trials with the recombinant protein as a novel treatment for human cancer. While TRAIL is very active in killing tumor cells, recombinant TRAIL possesses drug properties that limit its efficacy such as short serum half-life, instability, and the inability to cross the intact blood-brain barrier. To overcome these limitations we identified a small molecule inducer of the TRAIL gene, TIC10 that is superior to recombinant TRAIL in terms of stability, bioavailability, ability to cross the blood-brain barrier, cost of production, and spectrum of activity. Importantly, our data shows that TIC10 is highly active in several aggressive and therapy-resistant cancers. On a mechanistic level, TIC10 causes potent antitumor effects and TRAIL-induction that is mediated by the transcription factor Foxo3a, which directly regulates the TRAIL gene promoter. Furthermore, we found that TIC10 results in the dual inactivation of Akt and ERK, thereby inhibiting their constitutive phosphorylation of Fox3a and potentiating its translocation to the nucleus and binding to the TRAIL gene promoter (Allen et al, Science Translational Medicine, In Press, 2013). We hypothesize that TIC10 induces potent antitumor effects that require Akt- and ERK-mediated Foxo3a nuclear translocation and transcriptional activation of the TRAIL gene. To address the hypothesis we propose the following specific aims: Specific Aim #1: Identify TIC10-induced effects on Foxo3a expression, phosphorylation, and subcellular localization; Specific Aim #2: Elucidate the role of Akt and ERK kinases in the mechanism of action of TIC10; Specific Aim #3: Determine the differential regulation of TRAIL gene transcription by FOXO family members. These studies will create a comprehensive molecular understanding of how TIC10 harnesses Foxo3a to achieve its potent antitumor activity and also has the potential to undercover novel regulatory mechanisms of Foxo3a activity that are biologically significant. Preclinical cancer models including orthotopic xenografts and transgenic mice along with primary human tumor specimens will substantiate the efficacy and validate the mechanistic findings regarding TIC10 and Foxo3a. Together, these studies will elucidate key and novel regulatory mechanisms involving Foxo3a with the first-in-class molecule TIC10 to yield insight regarding its mechanism of action as well as in clinical samples in the context of colon cancer disease progression. Our studies will facilitate the clinical translation of a novel anti-cancer therapeutic agent through further development in preclinical laboratory studies.