osi-027 and Pancreatic-Neoplasms

The mTOR-inhibitor everolimus improves progression-free survival in advanced pancreatic neuroendocrine tumours (PNETs). However, adaptive resistance to mTOR inhibition is described.. QGP-1 and BON-1, two human PNET cell lines, were cultured with increasing concentrations of everolimus up to 22 weeks to reach a dose of 1 μM everolimus, respectively, 1000-fold and 250-fold initial IC50. Using total DNA content as a measure of cell number, growth inhibitory dose-response curves of everolimus were determined at the end of resistance induction and over time after everolimus withdrawal. Response to ATP-competitive mTOR inhibitors OSI-027 and AZD2014, and PI3K-mTOR inhibitor NVP-BEZ235 was studied. Gene expression of 10 PI3K-Akt-mTOR pathway-related genes was evaluated using quantitative real-time PCR (RT-qPCR).. Long-term everolimus-treated BON-1/R and QGP-1/R showed a significant reduction in everolimus sensitivity. During a drug holiday, gradual return of everolimus sensitivity in BON-1/R and QGP-1/R led to complete reversal of resistance after 10-12 weeks. Treatment with AZD2014, OSI-027 and NVP-BEZ235 had an inhibitory effect on cell proliferation in both sensitive and resistant cell lines. Gene expression in BON-1/R revealed downregulation of MTOR, RICTOR, RAPTOR, AKT and HIF1A, whereas 4EBP1 was upregulated. In QGP-1/R, a downregulation of HIF1A and an upregulation of ERK2 were observed.. Long-term everolimus resistance was induced in two human PNET cell lines. Novel PI3K-AKT-mTOR pathway-targeting drugs can overcome everolimus resistance. Differential gene expression profiles suggest different mechanisms of everolimus resistance in BON-1 and QGP-1.

Topics: Antineoplastic Agents; Cell Line, Tumor; Drug Resistance, Neoplasm; Everolimus; Gene Expression Profiling; Humans; Imidazoles; Neuroendocrine Tumors; Pancreatic Neoplasms; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Quinolines; TOR Serine-Threonine Kinases; Triazines

Despite its relative rarity, pancreatic ductal adenocarcinoma (PDAC) accounts for a large percentage of cancer deaths. In this study, we investigated the in vitro efficacy of OSI-027, a selective inhibitor of mammalian target of rapamycin complex 1 (mTORC1) and mTORC2, to treat PDAC cell lines alone, and in combination with gemcitabine (GEM). Similarly, we tested the efficacy of these two compounds in a xenograft mouse model of PDAC. OSI-027 significantly arrested cell cycle in G0/G1 phase, inhibited the proliferation of Panc-1, BxPC-3, and CFPAC-1 cells, and downregulated mTORC1, mTORC2, phospho-Akt, phospho-p70S6K, phospho-4E-BP1, cyclin D1, and cyclin-dependent kinase 4 (CDK4) in these cells. Moreover, OSI-027 also downregulated multidrug resistance (MDR)-1, which has been implicated in chemotherapy resistance in PDAC cells and enhanced apoptosis induced by GEM in the three PDAC cell lines. When combined, OSI-027 with GEM showed synergistic cytotoxic effects both in vitro and in vivo. This is the first evidence of the efficacy of OSI-027 in PDAC and may provide the groundwork for a new clinical PDAC therapy.

Topics: Animals; Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Pancreatic Ductal; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Survival; Deoxycytidine; Dose-Response Relationship, Drug; Drug Synergism; Gemcitabine; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Inhibitory Concentration 50; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Mice, Inbred BALB C; Mice, Nude; Multiprotein Complexes; Pancreatic Neoplasms; Protein Kinase Inhibitors; RNA Interference; Signal Transduction; Time Factors; TOR Serine-Threonine Kinases; Transfection; Triazines; Tumor Burden; Xenograft Model Antitumor Assays

In the present study, we investigated the potential activity of OSI-027, a potent and selective mammalian target of rapamycin (mTOR) complex 1/2 (mTORC1/2) dual inhibitor, against pancreatic cancer cells both in vitro and in vivo. We demonstrated that OSI-027 inhibited survival and growth of both primary and transformed (PANC-1 and MIA PaCa-2 lines) human pancreatic cancer cells. Meanwhile, OSI-027 induced caspase-dependent apoptotic death of the pancreatic cancer cells. On the other hand, caspase inhibitors alleviated cytotoxicity by OSI-027. At the molecular level, OSI-027 treatment blocked mTORC1 and mTORC2 activation simultaneously, without affecting ERK-mitogen-activated protein kinase activation. Importantly, OSI-027 activated cytoprotective autophagy in the above cancer cells. Whereas pharmacological blockage of autophagy or siRNA knockdown of Beclin-1 significantly enhanced the OSI-027-induced activity against pancreatic cancer cells. Specifically, a relatively low dose of OSI-027 sensitized gemcitabine-induced pancreatic cancer cell death in vitro. Further, administration of OSI-027 or together with gemcitabine dramatically inhibited PANC-1 xenograft growth in severe combined immunodeficiency mice, leading to significant mice survival improvement. In summary, the preclinical results of this study suggest that targeting mTORC1/2 synchronously by OSI-027 could be further investigated as a valuable treatment for pancreatic cancer.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; Cell Line, Tumor; Cell Survival; Deoxycytidine; Gemcitabine; Humans; Imidazoles; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Membrane Proteins; Mice, SCID; Multiprotein Complexes; Pancreatic Neoplasms; TOR Serine-Threonine Kinases; Triazines; Xenograft Model Antitumor Assays