gx-15-070 and Pancreatic-Neoplasms

The present study aimed to investigate the effects of obatoclax (OBX) combined with gemcitabine (GEM) treatment on the proliferation, migration, invasion and epithelial‑mesenchymal transition (EMT) related proteins of pancreatic cancer cell line BxPC‑3 under hypoxic conditions. Protein expression levels of hypoxia‑inducible factor 1α (HIF‑1α) in BxPC‑3 pancreatic cancer cells under normoxic and hypoxic conditions were detected by western blotting. Cells were divided into four groups: Normoxia group, hypoxia group, OBX group and OBX + GEM group. The proliferation activity of BxPC‑3 cells was detected by Cell Counting kit‑8. The migratory and invasive abilities of BxPC‑3 cells were detected by the scratch test and Matrigel assay, respectively. The protein expression levels of vimentin, E‑cadherin and p53 in BxPC‑3 cells were also detected by western blotting. HIF‑1α expression under hypoxic conditions was significantly increased compared with expression under normoxic conditions. Under hypoxic conditions, OBX treatment reduced cell activity, decreased cell migration and invasion, promoted the expression of E‑cadherin and p53. In the OBX + GEM group, BxPC‑3 cell activity decreased significantly, cell migration and invasion decreased significantly, the expression of vimentin was significantly reduced and the expression of E‑cadherin and p53 further increased. In conclusion, the present results demonstrated that under hypoxic conditions, OBX combined with a small dose of GEM may be able to inhibit the growth, migration and invasion of pancreatic cancer cells, possibly via inhibition of EMT process. These results may provide a promising strategy for pancreatic cancer therapy.

Topics: Antineoplastic Combined Chemotherapy Protocols; Cadherins; Cell Hypoxia; Cell Line, Tumor; Cell Movement; Deoxycytidine; Epithelial-Mesenchymal Transition; Gemcitabine; Humans; Indoles; Neoplasm Invasiveness; Pancreatic Neoplasms; Pyrroles; Tumor Suppressor Protein p53

In this study, we explored the antitumor activities of the PARP inhibitor AZD2281 (Olaparib) and the pan-Bcl-2 inhibitor GX15-070 (Obatoclax) in six pancreatic cancer cell lines. While both agents were able to cause growth arrest and limited apoptosis, the combination of the two was able to synergistically cause growth arrest and non-apoptotic cell death. Furthermore, in an in vivo xenograft model, the combination caused substantially increased tumor necrosis compared to either treatment alone. Our results support further investigation of the combination of Bcl-2 and PARP inhibitors for the treatment of pancreatic cancer.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; BRCA1 Protein; BRCA2 Protein; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Synergism; Enzyme Inhibitors; Female; Humans; Indoles; Mice, Inbred BALB C; Mice, Nude; Necrosis; Pancreatic Neoplasms; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Time Factors; Xenograft Model Antitumor Assays

Pancreatic cancer is an aggressive disease with a poor prognosis. Therefore, new treatment is urgently required. GX15-070 is a pan-Bcl-2 inhibitor which has shown promising antitumor activity in different malignancies. We previously demonstrated that clinically achievable concentrations of GX15-070 caused growth arrest in pancreatic cancer cell lines. However, they only induced minimal levels of apoptosis. We hypothesized that GX15-070 induced autophagy in pancreatic cancer cells which blocked apoptosis. In this study, we investigated the effects of GX15-070 on autophagy and the antitumor activities of the combination of GX15-070 and chloroquine (CQ), an autophagy inhibitor, in six pancreatic cancer cell lines. We found that GX15-070 treatment indeed induced autophagy in 5 of the 6 pancreatic cancer cell lines, reflected by the conversion of LC3B-I to LC3B-II and detection of autophagosomes by transmission electron microscopy. Furthermore, we found additive to synergistic antitumor interactions in all six cell lines by MTT assays. CQ significantly enhanced GX15-070-induced apoptosis in the cell line models, possibly due to downregulation of Bcl-2, Bcl-xL and Mcl-1 in the cells by the two agents. These results provide compelling evidence for the further development of the combination of GX15-070 and CQ in pancreatic cancer.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Autophagy; bcl-X Protein; Cell Line, Tumor; Chloroquine; Drug Synergism; Gene Expression Regulation, Neoplastic; Humans; Indoles; Myeloid Cell Leukemia Sequence 1 Protein; Pancreatic Neoplasms; Proto-Oncogene Proteins c-bcl-2; Pyrroles

Prosurvival Bcl-2 proteins inhibit the mitochondrial and death receptor-mediated apoptotic pathways. Obatoclax is a small-molecule antagonist of the BH3-binding groove of Bcl-2 proteins that may enhance tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) sensitivity and efficacy.. Human pancreatic cancer cell lines were incubated with obatoclax and/or TRAIL and cell viability, Annexin V labeling, caspase cleavage, and cytochrome c release were measured. In drug-treated cell lines, protein-protein interactions were studied by immunoprecipitation. Bax/Bak activation was analyzed using conformation-specific antibodies. Lentiviral short hairpin RNA was used to knockdown Bim, Bid, and apoptosis-inducing factor (AIF) expression.. Obatoclax reduced the viability of PANC-1 and BxPC-3 cell lines and synergistically enhanced TRAIL-mediated cytotoxicity. Obatoclax enhanced TRAIL-mediated apoptosis, as shown by Annexin V labeling, which was accompanied by caspase activation (caspase-8, -9, and -3) and cleavage of Bid. Obatoclax potentiated TRAIL-mediated Bax/Bak activation and the release of mitochondrial cytochrome c, Smac, and AIF. Mechanisms underlying the apoptotic effect of obatoclax include displacement of Bak from its sequestration by Bcl-x(L) or Mcl-1 and release of Bim from Bcl-2 or Mcl-1. Bid knockdown by short hairpin RNA attenuated caspase cleavage and cytotoxicity of obatoclax plus TRAIL. Bim knockdown failed to inhibit the cytotoxic effect of obatoclax alone or combined with TRAIL yet attenuated TRAIL-mediated cytotoxicity. AIF knockdown attenuated cytotoxicity of the drug combination.. Obatoclax potentiates TRAIL-mediated apoptosis by unsequestering Bak and Bim from Bcl-2/Bcl-x(L) or Mcl-1 proteins. This drug combination enhances Bid-mediated cross-talk between the mitochondrial and death receptor-mediated apoptotic pathways and may represent a novel therapeutic strategy against pancreatic cancer.

Topics: Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; BH3 Interacting Domain Death Agonist Protein; Caspases; Cell Line, Tumor; Cytochromes c; Humans; Indoles; Myeloid Cell Leukemia Sequence 1 Protein; Pancreatic Neoplasms; Proto-Oncogene Proteins c-bcl-2; Pyrroles; TNF-Related Apoptosis-Inducing Ligand