dactolisib and Pancreatic-Neoplasms

Treatment with BEZ235 has not been shown to demonstrate increased efficacy compared with everolimus and may be associated with a poorer tolerability profile.The hypothesis of dual targeting of the phosphatidylinositol 3-kinase and mammalian target of rapamycin pathways in patients with advanced pancreatic neuroendocrine tumors may warrant further study using other agents.. This phase II study investigated whether targeting the phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway via PI3K, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) inhibition using BEZ235 may be more effective than mTORC1 inhibition with everolimus in patients with advanced pancreatic neuroendocrine tumors (pNET) who are naïve to mTOR inhibitor therapy.. Patients with advanced pNET were randomized (1:1) to oral BEZ235 400 mg twice daily or oral everolimus 10 mg once daily on a continuous dosing schedule. The primary endpoint was progression-free survival (PFS). Secondary endpoints included safety, overall response rate (ORR), overall survival (OS), and time to treatment failure.. Enrollment in this study was terminated early (62 enrolled of the 140 planned). The median PFS was 8.2 months (95% confidence interval [CI]: 5.3 to not evaluable [NE]) with BEZ235 versus 10.8 months (95% CI: 8.1-NE) with everolimus (hazard ratio 1.53; 95% CI: 0.72-3.25). The most commonly reported all-grade adverse events (>50% of patients regardless of study treatment relationship) with BEZ235 were diarrhea (90.3%), stomatitis (74.2%), and nausea (54.8%).. BEZ235 treatment in mTOR inhibitor-naïve patients with advanced pNET did not demonstrate increased efficacy compared with everolimus and may be associated with a poorer tolerability profile.

Topics: Antineoplastic Agents; Everolimus; Female; Humans; Imidazoles; Male; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Middle Aged; Neuroendocrine Tumors; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Progression-Free Survival; Quinolines; TOR Serine-Threonine Kinases

This was a two-stage, phase II trial of the dual phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor BEZ235 in patients with everolimus-resistant pancreatic neuroendocrine tumours (pNETs) (NCT01658436).. In stage 1, 11 patients received 400 mg BEZ235 orally twice daily (bid). Due to tolerability concerns, a further 20 patients received BEZ235 300 mg bid. Stage 2 would be triggered by a 16-week progression-free survival (PFS) rate of ≥60% in stage 1.. As of 30 June, 2014, 29/31 patients had discontinued treatment. Treatment-related grade 3/4 adverse events were reported in eight (72.7%) patients at 400 mg and eight (40.0%) patients at 300 mg, including hyperglycaemia, diarrhoea, nausea, and vomiting. The estimated 16-week PFS rate was 51.6% (90% confidence interval=35.7-67.3%).. BEZ235 was poorly tolerated by patients with everolimus-resistant pNETs at 400 and 300 mg bid doses. Although evidence of disease stability was observed, the study did not proceed to stage 2.

Topics: Administration, Oral; Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Drug Administration Schedule; Drug Resistance, Neoplasm; Everolimus; Female; Humans; Imidazoles; Male; Middle Aged; Neuroendocrine Tumors; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinase; Phosphoinositide-3 Kinase Inhibitors; Prospective Studies; Protein Kinase Inhibitors; Quinolines; Time Factors; TOR Serine-Threonine Kinases; Treatment Outcome

Multi-drug resistance (MDR) develops because cancer cells evade toxicity of several structurally unrelated drugs. Besides other mechanisms, MDR is linked to the overexpression of ATP Binding Cassette (ABC), transporters, among which ABCB1 is the best characterized one. Since overactivation of PI3K/Akt/mTOR plays a pivotal role in the growth of human cancers, we hypothesized whether dual PI3K and mTOR inhibitor, BEZ235 (BEZ, dactolisib) reverses resistance to doxorubicin (DOX).. Ovarian (A2780) and pancreatic (MiaPaca2) cancer cells were used to generate DOX-resistant clones by overexpressing ABCB1 or stepwise treatment of DOX. Intracellular accumulation of DOX was measured by flow cytometry after treatment with BEZ.. BEZ treatment caused an increase in intracellular levels of DOX which was almost identical to the naïve parental cell lines. BEZ was found to be a weak substrate for ABCB1 as demonstrated by minimal increase in ATPase activity. BEZ treatment caused a dose-dependent decrease in cell viability in combination with DOX, which was associated with an increase in cleaved PARP expression in the drug resistant clones.. These results suggest that BEZ is a non-substrate inhibitor of ABCB1 and is able to effectively re-sensitize cells overexpressing ABCB1 to the effects of DOX.. Dual PI3 Kinase/mTOR inhibitor, BEZ, has the potential to reverse MDR in cancer patients.

Topics: ATP Binding Cassette Transporter, Subfamily B; Cell Line, Tumor; Doxorubicin; Drug Resistance, Neoplasm; Female; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Ovarian Neoplasms; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Quinolines; TOR Serine-Threonine Kinases

Tumor vessels are leaky and immature, which causes poor oxygen and nutrient supply to tumor vessels and results in cancer cell metastasis to distant organs. This instability of tumor blood vessels also makes it difficult for anticancer drugs to penetrate and reach tumors. Numerous tumor vessel normalization approaches have been investigated for improving drug delivery into tumors. In this study, we investigated whether phosphoinositide 3-kinase (PI3K) inhibitors are able to improve vascular structure and function over the prolonged period necessary to achieve effective vessel normalization. The PI3K inhibitors, HS-173 and BEZ235 potently suppressed tumor growth and hypoxia, and increased tumor apoptosis in animal models. PI3K inhibitors also induced a regular, flat monolayer of endothelial cells (ECs) in vessels, improving stability of vessel structure, and normalized tumor vessels by increasing vascular maturity, pericyte coverage, basement membrane thickness, and tight-junctions. These effects resulted in a decrease in tumor vessel tortuosity and vessel thinning, and improved vessel function and blood flow. The tumor vessel stabilization effect of the PI3K inhibitor HS-173 also decreased the number of metastatic lung nodules in vivo metastasis model. Furthermore, HS-173 improved the delivery of doxorubicin into the tumor region, enhancing its anticancer effects. Mechanistic studies suggested that PI3K inhibitor HS-173-induced vessel normalization reflected changes in endothelial Notch signaling. Taken together, our findings indicate that vessel normalization by PI3K inhibitors restrained tumor growth and metastasis while improving chemotherapy by enhancing drug delivery into the tumor, suggesting that HS-173 may have a therapeutic value as an enhancer or an anticancer drug.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Blood Vessels; Cell Line, Tumor; Cell Proliferation; Doxorubicin; Human Umbilical Vein Endothelial Cells; Humans; Imidazoles; Lung Neoplasms; Male; Melanoma, Experimental; Mice, Inbred BALB C; Mice, Nude; Neovascularization, Pathologic; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinase; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Pyridines; Quinolines; Signal Transduction; Sulfonamides; Time Factors; Tumor Burden; Tumor Hypoxia; Tumor Microenvironment; Xenograft Model Antitumor Assays

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

Extensive cross talk exists between PI3K/Akt/mTOR and mitogen-activated protein kinase (MAPK) pathways, and both are upregulated in pancreatic ductal adenocarcinoma (PDAC). Our previous study suggested that epidermal growth factor receptor inhibitor erlotinib which acts upstream of these pathways acts synergistically with PI3K inhibitors in PDAC. Horizontal combined blockade upstream and downstream of these two pathways is therefore explored.. Erlotinib paired with PI3K inhibitor (BYL719) was tested against erlotinib plus dual PI3K/mTOR inhibitor BEZ-235, and MEK inhibitor (PD98059) plus BEZ235, on five primary PDAC cell lines and on two pairs of parent and erlotinib-resistant (ER) cell lines. A range of in vitro assays including cell proliferation, Western blotting, migration, clonogenic, cell cycle, and apopotic assays was used to test for the efficacy of combined blockade.. Dual downstream blockade of the MAPK and PAM pathways was more effective in attenuating downstream molecular signals. Synergy was demonstrated for erlotinib and BEZ235 and for PD-98059 and BEZ-235. This resulted in a trend of increased growth cell cycle arrest, apoptosis, cell proliferation, and colony and migration suppression. This combination showed more efficacy in cell lines with acquired resistance to erlotinib.. The additional mTOR blockade provided by BEZ235 in combined blockade resulted in increased anticancer effect. The hypersensitivity of ER cell lines to additional mTOR blockade suggested PAM pathway oncogenic dependence via mTOR. Dual downstream combined blockade of MAPK and PAM pathways with MEK and PI3K/mTOR inhibitor appeared most effective and represents an attractive therapeutic strategy against pancreatic cancer and its associated drug resistance.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Pancreatic Ductal; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Movement; Cell Proliferation; Drug Resistance, Neoplasm; Drug Synergism; Erlotinib Hydrochloride; Flavonoids; Humans; Imidazoles; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Pancreatic Neoplasms; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Quinolines; Thiazoles; TOR Serine-Threonine Kinases

Chromosome 1p35-36, which encodes tumor suppressors and mitotic checkpoint control genes, is commonly altered in human malignancies. One gene at this locus, stathmin 1 (STMN1), is involved in cell cycle progression and metastasis. We hypothesized that increased STMN1 expression may play a role in pancreatic neuroendocrine neoplasm (pNEN) malignancy. We investigated stathmin copy number variation, mRNA, and protein expression using PCR-Taqman Copy Number Assays, Q-PCR, Western blot, and immunohistochemistry. A mechanistic role for stathmin in proliferation was assessed in the BON cell line under growth-restrictive conditions and siRNA silencing. Furthermore, its role in PI3K signaling pathway activation was evaluated using pharmacological inhibitors. mRNA (p = 0.0001) and protein (p < 0.05) were overexpressed in pNENs. Expression was associated with pNEN tumor extension (p < 0.05), size (p < 0.01), and Ki67 expression (p < 0.01). Serum depletion decreased Ki67 expression (p < 0.01) as well as Ser38 phosphorylation (p < 0.05) in BON cells. STMN1 knockdown (siRNA) decreased proliferation (p < 0.05), and PI3K inhibitors directly inhibited proliferation via stathmin inactivation (dephosphorylation p < 0.01). We identified that stathmin was overexpressed and associated with pathological parameters in pancreatic NENs. We postulate that STMN1 overexpression and phosphorylation result in a loss of cell cycle mitotic checkpoint control and may render tumors amenable to PI3K inhibitory therapy.

Topics: Cell Line, Tumor; Cell Proliferation; DNA Copy Number Variations; Gene Expression; Humans; Imidazoles; Liver Neoplasms; Neuroendocrine Tumors; Pancreas; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Processing, Post-Translational; Quinolines; RNA, Messenger; Signal Transduction; Stathmin

The PI3K/AKT/mTOR pathway, which is aberrantly stimulated in many cancer cells, has emerged as a target for therapy. However, mTORC1/S6K also mediates negative feedback loops that attenuate upstream signaling. Suppression of these feedback loops opposes the growth-suppressive effects of mTOR inhibitors and leads to drug resistance. Here, we demonstrate that treatment of PANC-1 or MiaPaCa-2 pancreatic ductal adenocarcinoma (PDAC) cells with the dual PI3K/mTOR kinase inhibitor (PI3K/TOR-KI) BEZ235 blocked mTORC1/S6K activation (scored by S6 phosphorylation at Ser(240/244)), mTORC1/4E-BP1 (assayed by 4E-BP1 phosphorylation at Thr(37/46)), and mTORC2-mediated AKT phosphorylation at Ser(473), in a concentration-dependent manner. Strikingly, BEZ235 markedly enhanced the MEK/ERK pathway in a dose-dependent manner. Maximal ERK overactivation coincided with complete inhibition of phosphorylation of AKT and 4E-BP1. ERK overactivation was induced by other PI3K/TOR-KIs, including PKI-587 and GDC-0980. The MEK inhibitors U126 or PD0325901 prevented ERK overactivation induced by PI3K/TOR-KIs. The combination of BEZ235 and PD0325901 caused a more pronounced inhibition of cell growth than that produced by each inhibitor individually. Mechanistic studies assessing PI3K activity in single PDAC cells indicate that PI3K/TOR-KIs act through a PI3K-independent pathway. Doses of PI3K/TOR-KIs that enhanced MEK/ERK activation coincided with those that inhibited mTORC2-mediated AKT phosphorylation on Ser(473), suggesting a role of mTORC2. Knockdown of RICTOR via transfection of siRNA markedly attenuated the enhancing effect of BEZ235 on ERK phosphorylation. We propose that dual PI3K/mTOR inhibitors suppress a novel negative feedback loop mediated by mTORC2, thereby leading to enhanced MEK/ERK pathway activity in pancreatic cancer cells.

Topics: Bridged Bicyclo Compounds, Heterocyclic; Carrier Proteins; Cell Line, Tumor; Cell Proliferation; Drug Synergism; ErbB Receptors; Gene Knockdown Techniques; Humans; Imidazoles; MAP Kinase Signaling System; Mechanistic Target of Rapamycin Complex 2; Morpholines; Multiprotein Complexes; Pancreatic Neoplasms; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Pyrimidines; Quinolines; Rapamycin-Insensitive Companion of mTOR Protein; Receptor, IGF Type 1; Receptor, Insulin; Receptors, Somatomedin; TOR Serine-Threonine Kinases; Triazines

Pancreatic cancer has the lowest 5-year survival rate of all major cancers despite decades of effort to design and implement novel, more effective treatment options. In this study, we tested whether the dual phosphoinositide 3-kinase/mechanistic target of rapamycin inhibitor BEZ235 (BEZ) potentiates the antitumor effects of doxorubicin (DOX) against pancreatic cancer. Cotreatment of BEZ235 with DOX resulted in dose-dependent inhibition of the phosphoinositide 3-kinase/mechanistic target of rapamycin survival pathway, which corresponded with an increase in poly ADP ribose polymerase cleavage. Moreover, BEZ cotreatment significantly improved the effects of DOX toward both cell viability and cell death in part through reduced Bcl-2 expression and increased expression of the shorter, more cytotoxic forms of BIM. BEZ also facilitated intracellular accumulation of DOX, which led to enhanced DNA damage and reactive oxygen species generation. Furthermore, BEZ in combination with gemcitabine reduced MiaPaca2 cell proliferation but failed to increase reactive oxygen species generation or BIM expression, resulting in reduced necrosis and apoptosis. Treatment with BEZ and DOX in mice bearing tumor xenographs significantly repressed tumor growth as compared with BEZ, DOX, or gemcitabine. Additionally, in contrast to the enhanced expression seen in MiaPaca2 cells, BEZ and DOX cotreatment reduced BIM expression in H9C2 cardiomyocytes. Also, the Bcl-2/Bax ratio was increased, which was associated with a reduction in cell death. In vivo echocardiography showed decreased cardiac function with DOX treatment, which was not improved by combination treatment with BEZ. Thus, we propose that combining BEZ with DOX would be a better option for patients than current standard of care by providing a more effective tumor response without the associated increase in toxicity.

Topics: Animals; Antibiotics, Antineoplastic; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Cardiotoxicity; Cell Survival; Doxorubicin; Drug Synergism; Female; HCT116 Cells; Humans; Imidazoles; Membrane Proteins; Mice; Mice, Nude; Myocytes, Cardiac; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Poly(ADP-ribose) Polymerases; Protein Kinase Inhibitors; Proto-Oncogene Proteins; Quinolines; Reactive Oxygen Species; TOR Serine-Threonine Kinases

Pancreatic endocrine tumors (PETs) are characterised by an indolent behaviour in terms of tumor growth. However, most patients display metastasis at diagnosis and no cure is currently available. Since the PI3K/AKT/mTOR axis is deregulated in PETs, the mTOR inhibitor RAD001 represents the first line treatment. Nevertheless, some patients do not respond to treatments and most acquire resistance. Inhibition of mTOR leads to feedback re-activation of PI3K activity, which may promote resistance to RAD001. Thus, PI3K represents a novel potential target for PETs. We tested the impact of three novel PI3K inhibitors (BEZ235, BKM120 and BYL719) on proliferation of PET cells that are responsive (BON-1) or unresponsive (QGP-1) to RAD001. BEZ235 was the most efficient in inhibiting proliferation in PET cells. Furthermore, combined treatment with BEZ235 and RAD001 exhibited synergic effects and was also effective in BON-1 that acquired resistance to RAD001 (BON-1 RR). Analysis of PI3K/AKT/mTOR pathway showed that RAD001 and BEZ235 only partially inhibited mTOR-dependent phosphorylation of 4EBP1. By contrast, combined therapy with the two inhibitors strongly inhibited phosphorylation of 4EBP1, assembly of the translational initiation complex and protein synthesis. Thus, combined treatment with BEZ235 may represent suitable therapy to counteract primary and acquired resistance to RAD001 in PETs.

Topics: Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cell Proliferation; Everolimus; Humans; Imidazoles; Neuroendocrine Tumors; Pancreatic Neoplasms; Phosphorylation; Quinolines; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Pancreatic adenocarcinoma is an aggressive type of malignancy and remains a treatment-refractory cancer. Because of the few treatment options, understanding of the molecular mechanisms is necessary, for new drugs be developed against molecular targets. Two of the novel, promising regimens against molecular targets, NVP-BEZ235 and MSK-777, were examined in three preclinical studies performed in human pancreatic cell lines and mouse models and presented in the 2013 ASCO Annual Meeting. Two of the studies evaluated the role of NVP-BEZ235, an oral phosphatidylinositol-3-kinase (PI3K) inhibitor, in pancreatic cancer treatment, alone and in combination with nab-paclitaxel (Abstract #e15007) or gemcitabine (Abstract #e15070). The third study presents the effectiveness of the novel cell division cycle 7 (Cdc7) kinase inhibitor, MSK-777 (Abstract #e15059). All studies demonstrated promising results and further investigation is ongoing.

Topics: Albumins; Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Cycle Proteins; Cell Line, Tumor; Cell Survival; Deoxycytidine; G1 Phase Cell Cycle Checkpoints; Gemcitabine; Humans; Imidazoles; Mice; Paclitaxel; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Quinolines; Signal Transduction; TOR Serine-Threonine Kinases; Tumor Burden; Xenograft Model Antitumor Assays

Gemcitabine has limited clinical benefits for pancreatic ductal adenocarcinoma (PDAC). The phosphatidylinositol-3-kinase (PI3K)/AKT and mammalian target of rapamycin (mTOR) signaling pathways are frequently dysregulated in PDAC. We investigated the effects of NVP-BEZ235, a novel dual PI3K/mTOR inhibitor, in combination with gemcitabine and endothelial monocyte activating polypeptide II (EMAP) in experimental PDAC. Cell proliferation and protein expression were analyzed by WST-1 assay and Western blotting. Animal survival experiments were performed in murine xenografts. BEZ235 caused a decrease in phospho-AKT and phospho-mTOR expression in PDAC (AsPC-1), endothelial (HUVECs), and fibroblast (WI-38) cells. BEZ235 inhibited in vitro proliferation of all four PDAC cell lines tested. Additive effects on proliferation inhibition were observed in the BEZ235-gemcitabine combination in PDAC cells and in combination of BEZ235 or EMAP with gemcitabine in HUVECs and WI-38 cells. BEZ235, alone or in combination with gemcitabine and EMAP, induced apoptosis in AsPC-1, HUVECs, and WI-38 cells as observed by increased expression of cleaved poly (ADP-ribose) polymerase-1 (PARP-1) and caspase-3 proteins. Compared to controls (median survival: 16 days), animal survival increased after BEZ235 and EMAP therapy alone (both 21 days) and gemcitabine monotherapy (28 days). Further increases in survival occurred in combination therapy groups BEZ235 + gemcitabine (30 days, P = 0.007), BEZ235 + EMAP (27 days, P = 0.02), gemcitabine + EMAP (31 days, P = 0.001), and BEZ235 + gemcitabine + EMAP (33 days, P = 0.004). BEZ235 has experimental PDAC antitumor activity in vitro and in vivo that is further enhanced by combination of gemcitabine and EMAP. These findings demonstrate advantages of combination therapy strategies targeting multiple pathways in pancreatic cancer treatment.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Proliferation; Cytokines; Deoxycytidine; Enzyme Inhibitors; Female; Fibroblasts; Gemcitabine; Human Umbilical Vein Endothelial Cells; Humans; Imidazoles; Mice; Mice, SCID; Neoplasm Proteins; Pancreatic Neoplasms; Phosphoinositide-3 Kinase Inhibitors; Quinolines; RNA-Binding Proteins; Signal Transduction; Survival Analysis; TOR Serine-Threonine Kinases

Genetic alterations activating K-RAS and PI3K/AKT signaling are also known to induce the activity of mTOR kinase through TORC1 and TORC2 complexes in human pancreatic ductal adenocarcinoma (PDAC). Here, we determined the effects of the dual PI3K and mTOR inhibitor, NVP-BEZ235 (BEZ235), and the pan-histone deacetylase inhibitor panobinostat (PS) against human PDAC cells. Treatment with BEZ235 or PS inhibited cell cycle progression with induction of the cell cycle inhibitory proteins, p21waf1 and p27kip1. BEZ235 and PS also dose dependently induced loss of cell viability of the cultured PDAC cells, associated with depletion of phosphorylated (p) AKT, as well as of the TORC1 substrates 4EBP1 and p70S6 kinase. While inhibiting p-AKT, treatment with PS induced the levels of the pro-apoptotic proteins BIM and BAK. Co-treatment with BEZ235 and PS synergistically induced apoptosis of the cultured PDAC cells. This was accompanied by marked attenuation of the levels of p-AKT and Bcl-xL but induction of BIM. Although in vivo treatment with BEZ235 or PS reduced tumor growth, co-treatment with BEZ235 and PS was significantly more effective in controlling the xenograft growth of Panc1 PDAC cells in the nude mice. Furthermore, co-treatment with BEZ235 and PS more effectively blocked tumor growth of primary PDAC heterotransplants (possessing K-RAS mutation and AKT2 amplification) subcutaneously implanted in the nude mice than each agent alone. These findings demonstrate superior activity and support further in vivo evaluation of combined treatment with BEZ235 and PS against PDAC that possess heightened activity of RAS-RAF-ERK1/2 and PI3K-AKT-mTOR pathways.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Cell Growth Processes; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Synergism; Enzyme Inhibitors; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Imidazoles; Indoles; Membrane Proteins; Mice; Mice, Nude; Pancreatic Neoplasms; Panobinostat; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Quinolines; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

The phosphatidylinositol-3-kinase (PI3K)/Akt signalling pathway is frequently deregulated in pancreatic cancers, and is believed to be an important determinant of their biological aggression and drug resistance. NVP-BEZ235 is a novel, dual class I PI3K/mammalian target of rapamycin (mTor) inhibitor undergoing phase I human clinical trials. To simulate clinical testing, the effects of NVP-BEZ235 were studied in five early passage primary pancreatic cancer xenografts, grown orthotopically. These tumours showed activated PKB/Akt, and increased levels of at least one of the receptor tyrosine kinases that are commonly activated in pancreatic cancers. Pharmacodynamic effects were measured following acute single doses, and anticancer effects were determined in separate groups following chronic drug exposure. Acute oral dosing with NVP-BEZ235 strongly suppressed the phosphorylation of PKB/Akt, followed by recovery over 24 h. There was also inhibition of Ser235/236 S6 ribosomal protein and Thr37/46 4E-BP1, consistent with the effects of NVP-BEZ235 as a dual PI3K/mTor inhibitor. Chronic dosing with 45 mg kg(-1) of NVP-BEZ235 was well tolerated, and produced significant tumour growth inhibition in three models. These results predict that agents targeting the PI3K/Akt/mTor pathway might have anticancer activity in pancreatic cancer patients, and support the testing of combination studies involving chemotherapy or other molecular targeted agents.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Cell Differentiation; Child; Enzyme Inhibitors; Humans; Imidazoles; Immunohistochemistry; Mice; Mice, SCID; Pancreatic Neoplasms; Phosphoinositide-3 Kinase Inhibitors; Protein Kinases; Quinolines; TOR Serine-Threonine Kinases; Transplantation, Heterologous