title: Human pancreatic carcinoma cells secrete bioactive interleukin-18 after treatment with 5-fluorouracil: implications for anti-tumor immune response.
abstract: Recently we observed that pancreatic carcinoma cell lines constitutively express Interleukin-18 (IL-18). Bioactive IL-18 induces Interferon (IFN)-gamma production, Fas Ligand (FasL) expression, and inhibits angiogenesis, raising the issue of anti-tumor effects of a tumor-derived cytokine and motivating a more detailed analysis of IL-18 production in pancreatic carcinoma cells. This analysis included the study of effects of chemotherapeutic drugs (5-fluorouracil [5-FU], gemcitabine, cisplatin) commonly used in the treatment of pancreatic cancer patients on IL-18 production and processing. IL-18 expression and post-translational processing were determined using RT-PCR, immunoblot and ELISA in pancreatic carcinoma cell lines and in tumor tissue and serum samples from pancreatic carcinoma patients in the presence and absence of chemotherapeutic drugs. We describe expression of IL-18 in pancreatic carcinoma cells and tissues associated with significantly elevated IL-18 levels in patients sera. Specifically, Capan-2 pancreatic tumor cells produced and secreted precursor IL-18 with no apparent biological activity. However, the chemotherapeutic agent 5-FU, by inducing Caspase-1 and Caspase-3 activation, induced secretion of proteolytically processed mature and degraded IL-18 species, respectively, in Capan-2 cells. Conditioned medium from 5-FU-treated but not control Capan-2 cells induced IFN-gamma production by activated T cells in an IL-18-dependent manner. Furthermore, adjuvant polychemotherapy including 5-FU significantly increased serum levels of mature, bioactive IL-18 in pancreatic carcinoma patients. Treatment of pancreatic cancer cells with 5-FU induced Caspase-dependent processing of pro-IL18 leading to the secretion of biologically active IL-18. These findings delineate a novel mechanism by which chemotherapeutic agents may modulate local anti-tumor cell-mediated immune responses.
authors.affiliation: Department of Gastroenterology and Clinical Nutrition, Azienda Ospedaliera San Giovanni Battista, Molinette, Turin, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Carbone
authors.forename: Ulrich
authors.initials: U
authors.lastname: Rodeck
authors.forename: Francesco Angelo
authors.initials: FA
authors.lastname: Mauri
authors.forename: Michela
authors.initials: M
authors.lastname: Sozzi
authors.forename: Fabio
authors.initials: F
authors.lastname: Gaspari
authors.forename: Carlo
authors.initials: C
authors.lastname: Smirne
authors.forename: Adriana
authors.initials: A
authors.lastname: Prati
authors.forename: Alfredo
authors.initials: A
authors.lastname: Addeo
authors.forename: Anna
authors.initials: A
authors.lastname: Novarino
authors.forename: Antonio
authors.initials: A
authors.lastname: Robecchi
authors.forename: Oscar
authors.initials: O
authors.lastname: Bertetto
authors.forename: Giorgio
authors.initials: G
authors.lastname: Emanuelli
authors.forename: Graziella
authors.initials: G
authors.lastname: Bellone
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D016022:Case-Control Studies; D020170:Caspase 1 / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D017077:Culture Media, Conditioned; D004789:Enzyme Activation / Q000187:drug effects*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use*; D006801:Humans; D015151:Immunoblotting; D007371:Interferon-gamma / Q000378:metabolism; D020382:Interleukin-18 / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D000964:Antimetabolites, Antineoplastic; D017077:Culture Media, Conditioned; D020382:Interleukin-18; D007371:Interferon-gamma; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D020170:Caspase 1; D005472:Fluorouracil