Simultaneous Ligand Directed Cytotoxic Toxin and Endosome Disruptor Delivery to Ablate Prostate Cancer
Technical Report,01 Aug 2018,31 Jul 2019
University of Arizona Tucson United States
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We proposed that the efficacy of G-protein coupled receptor GPCR ligand directed toxins is limited by sequestration and degradation in the endosome following endocytosis. We proposed that a GPCR ligand-endosome disruptor conjugate would enhance the efficacy of a GPCR ligand-toxin conjugate. We engineered E. Coli that synthesize listeriolysin O LLO, an endosome disruptor, and developed a fast protein liquid chromatography method to purify this LLO. We used solid state protein chemistry to synthesize gastrin release peptide GRP and gonadotropin releasing hormone GnRH then created conjugates with the ribosome inactivating protein toxin, Saporin, and the endosome disruptor, LLO. Both GRP-Saporin and GnRH-Saporin were effective in ablating two immortalized prostate cancer cell lines DU145 and PC3 cells in vitro, with GRP-Saporin effective at lower concentrations. The efficacy of both GRP-Saporin and GnRH-Saporin were enhanced by simultaneous treatment with LLO conjugates respectively. We are currently conducting research to complete in vivo mouse studies aimed at understanding the efficacy of these conjugates in a tumor implant model. These in vivo studies will include a GPCR ligand-doxorubicin conjugate to test the efficacy of endosome disruptors in preventing loss of efficacy due to endosomal sequestration. By including doxorubicin conjugates our findings may be more quickly applied to improve a compound in phase 3 clinical trials.
- Medicine and Medical Research