title: Cytotoxic responses to N-(4-hydroxyphenyl)retinamide in human pancreatic cancer cells.
abstract: OBJECTIVE
  Although fenretinide (4-HPR) has been studied in breast cancer and in neuroblastoma, little is known regarding its activity in pancreatic cancer, a neoplasm for which there are few therapeutic options. Since pancreatic cancer cells are susceptible to reactive oxygen species (ROS) and ceramide, two hallmarks of 4-HPR cytotoxicity, we investigated the effect of 4-HPR on human pancreatic cancer cells.
  
  
  METHODS
  Human pancreatic cancer cell lines MIA PaCa-2 and PANC-1 were treated with 4-HPR, followed by measurement of viability, proliferation, ROS and ceramide production, and Western blotting.
  
  
  RESULTS
  At the measured IC(50) of 10 μM, 4-HPR led to a 44-68% reduction in [(3)H]thymidine incorporation, a >3-fold increase in de novo ceramide levels, a 2.7-fold increase in ROS, and minor increases in markers of apoptosis. 4-HPR induced a robust, sustained increase in LC3 II expression and enhanced formation of acridine orange-stained acidic vesicles that are markers of autophagy. In addition, sustained, dose-dependent increases in JNK and p38 phosphorylation and decreased ERK phosphorylation were observed following treatment. Pretreatment with vitamin E, a ROS scavenger, and 3-methyladenine, an autophagy inhibitor, individually led to decreased sensitivity to 4-HPR; however, the de novo ceramide inhibitor myriocin had no effect.
  
  
  CONCLUSIONS
  These data show that 4-HPR triggers pancreatic cancer cell death by apoptosis and autophagy and that sensitivity appears to be mediated by ROS and not ceramide. This study is the first to characterize the response of human pancreatic cancer cells to 4-HPR and opens the door to investigations into this compound in pancreatic adenocarcinomas.
authors.affiliation: Department of Experimental Therapeutics, John Wayne Cancer Institute, Santa Monica, CA 90404, USA.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Messner
authors.forename: Myles C
authors.initials: MC
authors.lastname: Cabot
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002277:Carcinoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002518:Ceramides / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D017313:Fenretinide / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D020033:Protein Isoforms / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers; D002518:Ceramides; D016166:Free Radical Scavengers; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D017313:Fenretinide