px-478 and Carcinoma--Pancreatic-Ductal

Arsenic trioxide (ATO) has been selected as a promising treatment not only in leukemia but also in solid tumors. Previous studies showed that the cytotoxicity of ATO mainly depends on the induction of reactive oxygen species. However, ATO has only achieved a modest effect in pancreatic ductal adenocarcinoma, suggesting that the existing radical scavenging proteins, such as hypoxia inducible factor-1, attenuate the effect. The goal of this study is to investigate the effect of combination treatment of ATO plus PX-478 (hypoxia-inducible factor-1 inhibitor) and its underlying mechanism. Here, we showed that PX-478 robustly strengthened the anti-growth and pro-apoptosis effect of ATO on Panc-1 and BxPC-3 pancreatic cancer cells in vitro. Meanwhile, in vivo mouse xenograft models also showed the synergistic effect of ATO plus PX-478 compared with any single agent. Further studies showed that the anti-tumor effect of ATO plus PX-478 was derived from the reactive oxygen species-induced apoptosis. We next confirmed that Hypoxia-inducible factor-1 cleared reactive oxygen species by its downstream target, forkhead box O transcription factors, and this effect may justify the strategy of ATO plus PX-478 in the treatment of pancreatic cancer.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Arsenic Trioxide; Arsenicals; Binding Sites; Carcinoma, Pancreatic Ductal; Cell Line; Cell Proliferation; Dose-Response Relationship, Drug; Drug Synergism; Forkhead Box Protein O1; Gene Expression Regulation, Neoplastic; Heat-Shock Proteins; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Mice, Nude; Mustard Compounds; Oxidative Stress; Oxides; Pancreatic Neoplasms; Phenylpropionates; Promoter Regions, Genetic; Reactive Oxygen Species; RNA Interference; Signal Transduction; Time Factors; Transcriptional Activation; Transfection; Xenograft Model Antitumor Assays

Pancreatic ductal adenocarcinoma (PDAC) is the worst prognoses among all the malignancies. Now, gemcitabine (Gem) is the first line chemotherapeutic drug for advanced pancreatic cancer. However, Gem is usually ineffective to the PDAC because of high degree of drug resistance. Hypoxia and immune suppressive milieu are the best-described hallmarks of PDAC; therefore, we investigated the impact of hypoxia inducible factor-1 (HIF-1) inhibitor, PX-478, in combination with Gem on the induction of immunogenic cell death (ICD). We verified that combined treatment with Gem/PX-478 significantly enhanced the anti-tumor effect and increased proportion of tumor infiltrating T-lymphocytes in Panc02-bearing immune-competent but not in immune-deficient mice. Vaccination using Panc02 cell line treated with single agent or in combination showed significant anti-tumor effects. Pancreatic cell lines treated with Gem and PX-478 can induce an increase in eIF2α phosphorylation was correlated with down-regulation of HIF-1α and elicited exposure of CRT and release of HMGB1 and ATP. Only co-treated cells induced DC maturation/phagocytosis and IFN-γ secretion by cytotoxic T lymphocytes. Altogether, combined treatment with Gem/PX-478 showed significantly inhibition on tumor growth and anti-tumor immunization. We propose that inhibition HIF-1α elicits Gem-induced immune response and eliminates PDAC cells by inducing ICD.

Topics: Adenosine Triphosphate; Animals; Antineoplastic Combined Chemotherapy Protocols; Blotting, Western; Carcinoma, Pancreatic Ductal; Cell Death; Cell Line, Tumor; Deoxycytidine; DNA-Binding Proteins; Drug Synergism; Gemcitabine; HMGB1 Protein; Hypoxia-Inducible Factor 1, alpha Subunit; Immunization; Mice, Inbred C57BL; Mice, Nude; Microscopy, Fluorescence; Mustard Compounds; Pancreatic Neoplasms; Phenylpropionates; Phosphorylation; Survival Analysis; T-Lymphocytes; Transcription Factors; Tumor Burden