title: Mucin production determines sensitivity to bortezomib and gemcitabine             in pancreatic cancer cells.
abstract: The prognosis of pancreatic cancer remains disappointing due to a high intrinsic             resistance against chemotherapeutic agents. Standard gemcitabine therapies have             improved overall survival only marginally and recently, inhibition of the proteasome             by the boronic acid derivative bortezomib has been introduced as a novel therapeutic             strategy for solid and hematological malignancies including pancreatic cancer.             The mucus-producing pancreatic cancer cell line Capan-1 was cultured under standard             conditions and treated with different concentrations of gemcitabine or bortezomib.             Mucus production was suppressed by siRNA-mediated silencing of apomucin genes.             Cell proliferation was determined by 3H-thymidine incorporation and apoptosis             was quantified after propidium iodide staining by flow cytometry. Apoptotic cell             death was confirmed by TUNEL staining, determination of mitochondrial transmembrane             potential and assessment of caspase 3/7 activity. NFκB-activity was determined             by EMSA. The unfolded protein response (UPR) was further investigated by PCR,             Western blotting and caspase 12 activity assays. Silencing of MUC4 significantly             reduced expression of mucins for up to 5 days after transfection. While native             cells showed an increased sensitivity to bortezomib treatment, silenced cells             were more sensitive to gemcitabine treatment. Bortezomib induces mitochondrial             damage in native cells and also activates the UPR by splicing of Xbp-1 and induction             of CHOP, which is significantly reduced by silencing of MUC4. Our data suggest             that mucinous pancreatic cancers are more sensitive towards proteasome inhibition             by bortezomib and that alternative pathways of apoptosis are involved in cell             death induction, while tumor cells with a low secretory activity show a better             response to gemcitabine.
authors.affiliation: Division of Gastroenterology, University Hospital of the Phillips-University Marburg, Baldingerstrasse, 35043 Marburg, Germany. wissniowski@me.com
authors.forename: Thaddäus Till
authors.initials: TT
authors.lastname: Wissniowski
authors.forename: Silke
authors.initials: S
authors.lastname: Meister
authors.forename: Eckhart G
authors.initials: EG
authors.lastname: Hahn
authors.forename: Joachim R
authors.initials: JR
authors.lastname: Kalden
authors.forename: Reinhard
authors.initials: R
authors.lastname: Voll
authors.forename: Matthias
authors.initials: M
authors.lastname: Ocker
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053454:Caspase 12 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D020287:In Situ Nick-End Labeling; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009077:Mucins / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016133:Polymerase Chain Reaction; D011480:Protease Inhibitors / Q000494:pharmacology*; D011719:Pyrazines / Q000494:pharmacology*; D034622:RNA Interference; D000071701:Regulatory Factor X Transcription Factors; D013997:Time Factors; D051742:Transcription Factor CHOP / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D056811:Unfolded Protein Response / Q000187:drug effects; D000071717:X-Box Binding Protein 1; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D001897:Boronic Acids; C497249:DDIT3 protein, human; D004268:DNA-Binding Proteins; D009077:Mucins; D016328:NF-kappa B; D011480:Protease Inhibitors; D011719:Pyrazines; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; D003841:Deoxycytidine; D051742:Transcription Factor CHOP; D000069286:Bortezomib; C506444:CASP12 protein, human; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053454:Caspase 12; D053148:Caspase 3; D053179:Caspase 7; D000093542:Gemcitabine