Abstract 3549: DeltaNp63 overexpression induced cytokines and chemokines attract type2 suppressive inflammatory infiltrates through NF-kappaB activation in dysplastic and malignant epithelia

Abstract

Abstract We and others have previously reported that overexpression of DeltaNp63, a TP53 family member and antagonist, is often accompanied by inflammation in pre-malignant as well as cancerous lesions. However, the molecular and cellular nature of the DeltaNp63-induced inflammation and whether it favors tumorigenesis is presently unclear. Here, we report that induced expression of DeltaNp63 in the basal epidermis of transgenic (Tg) mice leads to skin erythema with a microscopically hyperproliferative epidermis and heavy infiltration of inflammatory cells. In situ phenotypic analysis of the infiltrating cells revealed increased recruitment of F4/80+ and CD11b+ macrophages, Ly6B+ neutrophils, S-100+ dentritic cells, CD45+ leukocytes, and CD3+ lymphocytes. Macrophages of the suppressive M2 phenotype were identified as a CD68+ and F4/80+/CD206+ double positive subpopulation. Transcriptome analysis of the skin lesions from DeltaNp63 Tg mice revealed 683 up-regulated genes, ∼19% of which were specifically involved in inflammation/immune responses and related signaling pathways, including many cytokine and chemokine genes. These inflammatory cytokines and chemokines inferred predominant T helper 2 and M2 signatures, and formed network connections with NF-kappaB by Ingenuity Pathway Analysis. We annotated promoter regions of these cytokine and chemokine genes by Genomatix, most of which contained predicted NF-kappaB binding consensus motifs. In addition, in human squamous cell carcinoma (SCC) lines, we showed that DeltaNp63-mediated promoter activities of chemokines and cytokines were partially blocked by knockdown of DeltaNp63, and either NF-kappaB RELA/p65 or c-REL. The reporter activities were significantly diminished when NF-kappaB sites were mutated. Supporting DeltaNp63 activation of the NF-kappaB pathway in vivo, we observed increased expression of phosphorylated NF-κB RelA/p65 (pS276), c-Rel, IKKalpha and IKKbeta in the hyperproliferative skin of DeltaNp63 Tg mice. Consistent with the aforementioned data, we observed overexpression of DeltaNp63, increased infiltrating inflammatory cells, and elevated immunohistochemistry of NF-κB signaling molecules in human SCC tissues. Together, our data support a model in which the elevated level of DeltaNp63 in the epidermis promotes NF-kappaB activation and a skewed spectrum of cytokines and chemokines, which in turn trigger type 2 suppressive inflammatory responses with characteristics of those reported in pre- and malignant squamous epithelia. Our data suggest that the most frequently mutated and aberrantly expressed TP53 family members could trigger inflammatory and immune responses, which favor tumorigenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3549. doi:1538-7445.AM2012-3549