title: Inhibitory effect of fluoxetine on lymphoma growth through the modulation of antitumor T-cell response by serotonin-dependent and independent mechanisms.
abstract: Fluoxetine, a selective serotonin reuptake inhibitor, is widely used for the treatment of depressive symptoms of cancer patients. However, there are contradictory evidences about its effects on immunity and cancer. Thus, we studied the effects of fluoxetine on tumor growth and on antitumoral T-cell-mediated immunity. In vivo chronic fluoxetine treatment inhibited tumor growth, and increased latency of appearance of solid tumors and survival of mice. Fluoxetine administration also increased mitogen-induced T-cell proliferation and Tumor Necrosis Factor-alpha (TNF-alpha) and Interferon-gamma (IFN-gamma) expression, without altering CD4(+)/CD8(+) ratio. In vitro, fluoxetine did not affect tumor cells proliferation, but it exerted a direct effect on T lymphocytes. Both fluoxetine and serotonin stimulated proliferation induced by a suboptimal mitogen concentration but inhibited proliferation at the optimal one. When both drugs were combined the results indicated that the effects of fluoxetine are in part independent of its ability to elevate serotonin extracellular levels. Finally, continue fluoxetine administration in nude mice - devoid of T lymphocytes - did not modify tumor progression, thus supporting the hypothesis of an immuno-modulatory effect of this drug on T cells that drives tumor growth control. These findings indicate, for the first time, that fluoxetine inhibits tumor growth through modulation of T-cell-mediated immunity by the already known serotonin-dependent pathway and by a novel independent mechanism.
authors.affiliation: Centro de Estudios Farmacológicos y Botánicos, Consejo Nacional de Investigaciones Científicas y Técnicas, 1 Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Luciana Romina
authors.initials: LR
authors.lastname: Frick
authors.forename: María Laura
authors.initials: ML
authors.lastname: Palumbo
authors.forename: María Paula
authors.initials: MP
authors.lastname: Zappia
authors.forename: Marcela Adriana
authors.initials: MA
authors.lastname: Brocco
authors.forename: Graciela Alicia
authors.initials: GA
authors.lastname: Cremaschi
authors.forename: Ana María
authors.initials: AM
authors.lastname: Genaro
mesh_terms: D000818:Animals; D016516:CD4-CD8 Ratio; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D016207:Cytokines / Q000096:biosynthesis; D005260:Female; D005473:Fluoxetine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D007111:Immunity, Cellular / Q000187:drug effects; D008198:Lymph Nodes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D016399:Lymphoma, T-Cell / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000473:pathology
chemical_list: D016207:Cytokines; D005473:Fluoxetine; D012701:Serotonin; D017367:Selective Serotonin Reuptake Inhibitors