RESUMO
Chemokines mediate the signaling and migration of T cells, but little is known about the transcriptional events involved therein. Microarray analysis of CXC chemokine ligand (CXCL) 12-treated T cells revealed that Wnt ligands are significantly up-regulated during CXCL12 treatment. Real-time polymerase chain reaction and Western blot analysis confirmed that the expression of noncanonical Wnt pathway members (eg, Wnt5A) was specifically up-regulated during CXCL12 stimulation, whereas beta-catenin and canonical Wnt family members were selectively down-regulated. Wnt5A augmented signaling through the CXCL12-CXCR4 axis via the activation of protein kinase C. Moreover, Wnt5A expression was required for CXCL12-mediated T-cell migration, and rWnt5A sensitized human T cells to CXCL12-induced migration. Furthermore, Wnt5A expression was also required for the sustained expression of CXCR4. These results were further supported in vivo using EL4 thymoma metastasis as a model of T-cell migration. Together, these data demonstrate that Wnt5A is a critical mediator of CXCL12-CXCR4 signaling and migration in human and murine T cells.
Assuntos
Movimento Celular/imunologia , Quimiocina CXCL12/imunologia , Proteínas Proto-Oncogênicas/imunologia , Transdução de Sinais/imunologia , Linfócitos T/imunologia , Proteínas Wnt/imunologia , Animais , Linhagem Celular Tumoral , Movimento Celular/genética , Quimiocina CXCL12/genética , Quimiocina CXCL12/metabolismo , Humanos , Camundongos , Camundongos Mutantes , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Receptores CXCR4/genética , Receptores CXCR4/imunologia , Receptores CXCR4/metabolismo , Transdução de Sinais/genética , Linfócitos T/metabolismo , Regulação para Cima/genética , Regulação para Cima/imunologia , Proteínas Wnt/genética , Proteínas Wnt/metabolismo , Proteína Wnt-5a , beta Catenina/genética , beta Catenina/imunologiaRESUMO
There are currently no effective therapies for metastatic melanoma and targeted immunotherapy results in the remission of only a very small percentage of tumors. In this study, we show that the noncanonical Wnt ligand, Wnt5A, can increase melanoma metastasis in vivo while down-regulating the expression of tumor-associated antigens important in eliciting CTL responses (e.g., MART-1, GP100, and tyrosinase). Melanosomal antigen expression is governed by MITF, PAX3, and SOX10 and is inhibited upon signal transducers and activators of transcription 3 (STAT3) activation, via decreases in PAX3 and subsequently MITF expression. Increasing Wnt5A in Wnt5A-low cells activated STAT3, and STAT3 was decreased upon Wnt5A knockdown. Downstream targets such as PAX3, MITF, and MART-1 were also affected by Wnt5A treatment or knockdown. Staining of a melanoma tissue array also highlighted the inverse relationship between MART-1 and Wnt5A expression. PKC activation by phorbol ester mimicked Wnt5A effects, and Wnt5A treatment in the presence of STAT3 or PKC inhibitors did not lower MART-1 levels. CTL activation studies showed that increases in Wnt5A correspond to decreased CTL activation and vice versa, suggesting that targeting Wnt5A before immunotherapy may lead to the enhancement of current targeted immunotherapy for patients with metastatic melanoma.