title: NFATc2 is an intrinsic regulator of melanoma dedifferentiation.
abstract: Melanoma dedifferentiation, characterized by the loss of MITF and MITF regulated genes and by upregulation of stemness markers as CD271, is implicated in resistance to chemotherapy, target therapy and immunotherapy. The identification of intrinsic mechanisms fostering melanoma dedifferentiation may provide actionable therapeutic targets to improve current treatments. Here, we identify NFATc2 transcription factor as an intrinsic regulator of human melanoma dedifferentiation. In panels of melanoma cell lines, NFATc2 expression correlated inversely with MITF at both mRNA and protein levels. NFATc2(+/Hi) melanoma cell lines were CD271(+) and deficient for expression of melanocyte differentiation antigens (MDAs) MART-1, gp100, tyrosinase and of GPNMB, PGC1-α and Rab27a, all regulated by MITF. Targeting of NFATc2 by small interfering RNA, short hairpin RNA and by an NFATc2 inhibitor upregulated MITF, MDAs, GPNMB, PGC-1α, tyrosinase activity and pigmentation and suppressed CD271. Mechanistically, we found that NFATc2 controls melanoma dedifferentiation by inducing expression in neoplastic cells of membrane-bound tumor necrosis factor-α (mTNF-α) and that melanoma-expressed TNF-α regulates a c-myc-Brn2 axis. Specifically, NFATc2, mTNF-α and expression of TNF receptors were significantly correlated in panels of cell lines. NFATc2 silencing suppressed TNF-α expression, and neutralization of melanoma-expressed TNF-α promoted melanoma differentiation. Moreover, silencing of NFATc2 and TNF-α neutralization downmodulated c-myc and POU3F2/Brn2. Brn2 was strongly expressed in NFATc2(+/Hi) MITF(Lo) cell lines and its silencing upregulated MITF. Targeting of c-myc, by silencing or by a c-myc inhibitor, suppressed Brn2 and upregulated MITF and MART-1 in melanoma cells. The relevance of NFATc2-dependent melanoma dedifferentiation for immune escape was shown by cytolytic T-cell assays. NFATc2(Hi) MITF(Lo) MDA(Lo) HLA-A2.1(+) melanoma cells were poorly recognized by MDA-specific and HLA-A2-restricted CTL lines, but NFATc2 targeting significantly increased CTL-mediated tumor recognition. Taken together, these results suggest that the expression of NFATc2 promotes melanoma dedifferentiation and immune escape.
authors.affiliation: Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Perotti
authors.affiliation: Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Baldassari
authors.affiliation: Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Molla
authors.affiliation: Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Vegetti
authors.affiliation: Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Bersani
authors.affiliation: Melanoma and Sarcoma Unit, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Maurichi
authors.affiliation: Melanoma and Sarcoma Unit, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Santinami
authors.affiliation: Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Anichini
authors.affiliation: Human Tumors Immunobiology Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Mortarini
mesh_terms: D000068816:Adapalene / Q000378:metabolism; D054337:Cell Dedifferentiation; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D008545:Melanoma / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D058950:Melanoma-Specific Antigens / Q000378:metabolism; D051739:Microphthalmia-Associated Transcription Factor / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D050809:POU Domain Factors / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D019139:Tumor Escape
chemical_list: D018398:Homeodomain Proteins; D058950:Melanoma-Specific Antigens; D051739:Microphthalmia-Associated Transcription Factor; D050778:NFATC Transcription Factors; D050809:POU Domain Factors; D016271:Proto-Oncogene Proteins c-myc; C085076:transcription factor Brn-2; D000068816:Adapalene