5-(4-amino-1-propan-2-yl-3-pyrazolo[3-4-d]pyrimidinyl)-1-3-benzoxazol-2-amine and Prostatic-Neoplasms

Both mammalian target of rapamycin (mTOR) complexes 1 and 2 (mTORC1/2) are often over-activated in prostate cancer cells and are associated with cancer progression. In the current study, we evaluated the potential anti-prostate cancer activity of INK-128, an ATP-competitive mTORC1/2 dual inhibitor, both in vitro and in vivo. Our results showed that INK-128 exerted potent anti-proliferative activity in established (PC-3 and LNCaP lines) and primary (patient-derived) human prostate cancer cells by inducing cell apoptosis. The latter was evidenced by increase of annexin V percentage, formation of cytoplasmic histone-associated DNA fragments, and cleavage of caspase-3. INK-128-induced prostate cancer cell apoptosis and cytotoxicity were alleviated upon pretreatment of cells with the pan-caspase inhibitor z-VAD-FMK or the specific caspase-3 inhibitor z-DVED-FMK. At the molecular level, INK-18 blocked mTORC1/2 activation in PC-3 cells and LNCaP cells and downregulated mTOR-regulated genes including cyclin D1, hypoxia-inducible factor 1α (HIF-1α), and HIF-2α. ERK-MAPK activation and androgen receptor expression were, however, not affected by INK-128 treatment. In vivo, oral administration of INK-128 significantly inhibited growth of PC-3 xenografts in nude mice. The preclinical results of this study suggest that INK-128 could be further investigated as a promising anti-prostate cancer agent.

Topics: Animals; Apoptosis; Benzoxazoles; Blotting, Western; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Male; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Mice; Mice, Nude; Multiprotein Complexes; Prostatic Neoplasms; Pyrimidines; TOR Serine-Threonine Kinases; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

The mammalian target of rapamycin (mTOR) kinase is a master regulator of protein synthesis that couples nutrient sensing to cell growth and cancer. However, the downstream translationally regulated nodes of gene expression that may direct cancer development are poorly characterized. Using ribosome profiling, we uncover specialized translation of the prostate cancer genome by oncogenic mTOR signalling, revealing a remarkably specific repertoire of genes involved in cell proliferation, metabolism and invasion. We extend these findings by functionally characterizing a class of translationally controlled pro-invasion messenger RNAs that we show direct prostate cancer invasion and metastasis downstream of oncogenic mTOR signalling. Furthermore, we develop a clinically relevant ATP site inhibitor of mTOR, INK128, which reprograms this gene expression signature with therapeutic benefit for prostate cancer metastasis, for which there is presently no cure. Together, these findings extend our understanding of how the 'cancerous' translation machinery steers specific cancer cell behaviours, including metastasis, and may be therapeutically targeted.

Topics: Adaptor Proteins, Signal Transducing; Animals; Benzoxazoles; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Eukaryotic Initiation Factor-4E; Eukaryotic Initiation Factors; Gene Expression Regulation, Neoplastic; Genome; Humans; Male; Mice; Mice, Inbred C57BL; Neoplasm Invasiveness; Neoplasm Metastasis; Phosphoproteins; Prostatic Neoplasms; Protein Biosynthesis; Pyrimidines; Repressor Proteins; RNA, Messenger; Signal Transduction; TOR Serine-Threonine Kinases