title: In vivo Effects in Melanoma of ROCK Inhibition-Induced FasL Overexpression.
abstract: Ectopic Fas-ligand (FasL) expression in tumor cells is responsible for both tumor escape through tumor counterattack of Fas-positive infiltrating lymphocytes and tumor rejection though inflammatory and immune responses. We have previously shown that RhoA GTPase and its effector ROCK negatively control FasL membrane expression in murine melanoma B16F10 cells. In this study, we found that B16F10 treatment with the ROCK inhibitor H1152 reduced melanoma development in vivo through FasL membrane overexpression. Although H1152 treatment did not reduce tumor growth in vitro, pretreatment of tumor cells with this inhibitor delayed tumor appearance, and slowed tumor growth in C57BL/6 immunocompetent mice. Thanks to the use of mice-bearing mutated Fas receptors (B6/lpr), we found that reduced tumor growth, observed in immunocompetent mice, was linked to FasL overexpression induced by H1152 treatment. Tumor growth analysis in immunosuppressed NUDE and IFN-γ-KO mice highlighted major roles for T lymphocytes and IFN-γ in the H1152-induced tumor growth reduction. Histological analyses of subcutaneous tumors, obtained from untreated versus H1152-treated B16F10 cells, showed that H1152 pretreatment induced a strong intratumoral infiltration of leukocytes. Cytofluorometric analysis showed that among these leukocytes, the number of activated CD8 lymphocytes was increased. Moreover, their antibody-induced depletion highlighted their main responsibility in tumor growth reduction. Subcutaneous tumor growth was also reduced by repeated intravenous injections of a clinical ROCK inhibitor, Fasudil. Finally, H1152-induced ROCK inhibition also reduced pulmonary metastasis implantation independently of T cell-mediated immune response. Altogether, our data suggest that ROCK inhibitors could become interesting pharmacological molecules for melanoma immunotherapy.
authors.affiliation: Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France.
authors.forename: Iotefa
authors.initials: I
authors.lastname: Teiti
authors.affiliation: Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Florie
authors.affiliation: Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France.
authors.forename: Christine
authors.initials: C
authors.lastname: Pich
authors.affiliation: Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Gence
authors.affiliation: Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lajoie-Mazenc
authors.affiliation: Université Paul Sabatier , Toulouse , France ; Institut Universitaire du Cancer de Toulouse , Toulouse , France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Rochaix
authors.affiliation: Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France ; Institut Universitaire du Cancer de Toulouse , Toulouse , France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Favre
authors.affiliation: Unité INSERM UMR 1037, CRCT , Toulouse , France ; Université Paul Sabatier , Toulouse , France.
authors.forename: Anne-Françoise
authors.initials: AF
authors.lastname: Tilkin-Mariamé
keywords: FasL; H1152; ROCK; immune response; melanoma