The transcriptional regulator Sin3A balances IL-17A and Foxp3 expression in primary CD4 T cells.

The Sin3 transcriptional regulator homolog A (Sin3A) is the core member of a multiprotein chromatin-modifying complex. Its inactivation at the CD4/CD8 double-negative stage halts further thymocyte development. Among various functions, Sin3A regulates STAT3 transcriptional activity, central to the differentiation of Th17 cells active in inflammatory disorders and opportunistic infections. To further investigate the consequences of conditional Sin3A inactivation in more mature precursors and post-thymic T cell, we have generated CD4-Cre and CD4-CreERT2 Sin3AF/F mice. Sin3A inactivation in vivo hinders both thymocyte development and peripheral T-cell survival. In vitro, in Th17 skewing conditions, Sin3A-deficient cells proliferate and acquire memory markers and yet fail to properly upregulate Il17a, Il23r, and Il22. Instead, IL-2+ and FOXP3+ are mostly enriched for, and their inhibition partially rescues IL-17A+ T cells. Notably, Sin3A deletion also causes an enrichment of genes implicated in the mTORC1 signaling pathway, overt STAT3 activation, and aberrant cytoplasmic RORγt accumulation. Thus, together our data unveil a previously unappreciated role for Sin3A in shaping critical signaling events central to the acquisition of immunoregulatory T-cell phenotypes.

Topical neurokinin-1 receptor antagonist Fosaprepitant ameliorates ocular graft-versus-host disease in a preclinical mouse model.

PURPOSE: to assess the effect of topical administration of the Neurokin-1 receptor (NK1R) antagonist Fosaprepitant in a pre-clinical model of ocular Graft-versus-Host disease (GVHD). METHODS: BALB/c mice were pre-conditioned by myeloablative total body irradiation and subjected to allogeneic bone marrow transplantation and mature T cell infusion (BM + T). BM-transplanted mice (BM) were used as controls. Ocular GVHD was specifically assessed by quantifying corneal epithelial damage, tear secretion, blepharitis and phimosis, 3 times/week for 28 days post-transplantation. A group of BM + T mice received Fosaprepitant 10 mg/mL, 6 times/day, topically, from day 7-29 after transplantation. After sacrifice, the expression of NK1R, CD45, CD3, and CXCL10 was quantified in the cornea, conjunctiva, and lacrimal gland by immunohistochemistry. RESULTS: BM + T mice developed corneal epithelial damage (day 0-29, p < 0.001), blepharitis (day 0-29, p < 0.001), and phimosis (day 0-29, p < 0.01), and experienced decreased tear secretion (day 21, p < 0.01) compared to controls. NK1R was found upregulated in corneal epithelium (p < 0.01) and lacrimal gland (p < 0.01) of BM + T mice. Fosaprepitant administration significantly reduced corneal epithelial damage (p < 0.05), CD45+ (p < 0.05) and CD3+ (p < 0.01) immune cell infiltration in the cornea and conjunctiva (p < 0.001 and p < 0.001, respectively). In addition, Fosaprepitant reduced the expression of CXCL10 in the cornea (p < 0.05) and in the lacrimal gland (p < 0.05). CONCLUSIONS: Our results suggest that NK1R represents a novel druggable pathway for the therapy of ocular GVHD.

The Transcriptional Regulator Sin3A Contributes to the Oncogenic Potential of STAT3.

Epigenetic silencing of promoter and enhancer regions is a common phenomenon in malignant cells. The transcription factor STAT3 is aberrantly activated in several tumors, where its constitutive acetylation accounts for the transcriptional repression of a number of tumor suppressor genes (TSG) via molecular mechanisms that remain to be understood. Using nucleophosmin-anaplastic lymphoma kinase-positive (NPM-ALK+) anaplastic large-cell lymphoma (ALCL) as model system, we found in cells and patient-derived tumor xenografts that STAT3 is constitutively acetylated as a result of ALK activity. STAT3 acetylation relied on intact ALK-induced PI3K- and mTORC1-dependent signaling and was sensitive to resveratrol. Resveratrol lowered STAT3 acetylation, rescued TSG expression, and induced ALCL apoptotic cell death. STAT3 constitutively bound the Sin3A transcriptional repressor complex, and both STAT3 and Sin3A bound the promoter region of silenced TSG via a resveratrol-sensitive mechanism. Silencing SIN3A caused reexpression of TSG, induced ALCL apoptotic cell death in vitro, and hindered ALCL tumorigenic potential in vivo. A constitutive STAT3-Sin3A interaction was also found in breast adenocarcinoma cells and proved critical for TSG silencing and cell survival. Collectively, these results suggest that oncogene-driven STAT3 acetylation and its constitutive association with Sin3A represent novel and concomitant events contributing to STAT3 oncogenic potential. SIGNIFICANCE: This study delineates the transcriptional regulatory complex Sin3A as a mediator of STAT3 transcriptional repressor activity and identifies the STAT3/Sin3A axis as a druggable target to antagonize STAT3-addicted tumors. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/79/12/3076/F1.large.jpg.See related commentary by Monteleone and Poli, p. 3031.