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New York City, NY, United States

Lopez-Rivera E.,Mount Sinai School of Medicine | Jayaraman P.,Mount Sinai School of Medicine | Parikh F.,Mount Sinai School of Medicine | Davies M.A.,University of Houston | And 9 more authors.
Cancer Research | Year: 2014

Melanoma is one of the cancers of fastest-rising incidence in the world. Inducible nitric oxide synthase (iNOS) is overexpressed in melanoma and other cancers, and previous data suggest that iNOS and nitric oxide (NO) drive survival and proliferation of human melanoma cells. However, specific mechanisms through which this occurs are poorly defined. One candidate is the PI3K-AKT-mTOR pathway, which plays a major role in proliferation, angiogenesis, and metastasis of melanoma and other cancers. We used the chick embryo chorioallantoic membrane (CAM) assay to test the hypothesis that melanoma growth is regulated by iNOS-dependent mTOR pathway activation. Both pharmacologic inhibition and siRNA-mediated gene silencing of iNOS suppressed melanoma proliferation and in vivo growth on the CAM in human melanoma models. This was associated with strong downregulation ofmTORpathway activation by Western blot analysis of p-mTOR, p70 ribosomal S6 kinase (p-P70S6K), p-S6RP, and p-4EBP1. iNOS expression and NO were associated with reversible nitrosylation of tuberous sclerosis complex (TSC) 2, and inhibited dimerization of TSC2 with its inhibitory partner TSC1, enhancing GTPase activity of its target Ras homolog enriched in brain (Rheb), a critical activator of mTOR signaling. Immunohistochemical analysis of tumor specimens from stage III melanoma patients showed a significant correlation between iNOS expression levels and expression of the mTOR pathway members. Exogenously supplied NO was also sufficient to reverse the mTOR pathway inhibition by the B-Raf inhibitor vemurafenib. In summary, covalent modification of TSC2 by iNOS-derived NO is associated with impaired TSC2/TSC1 dimerization, mTOR pathway activation, and proliferation of human melanoma. This model is consistent with the known association of iNOS overexpression and poor prognosis in melanoma and other cancers. © 2014 American Association for Cancer Research.

Pintova S.,One Gustave L. Levy Place | Sidhu H.,Mount Sinai School of Medicine | Friedlander P.A.,One Gustave L. Levy Place | Holcombe R.F.,One Gustave L. Levy Place
Melanoma Research | Year: 2013

Sweet's syndrome, a neutrophilic dermatosis, is a known paraneoplastic complication occurring with various malignancies. It has been infrequently reported in association with melanoma. Ipilimumab is an antibody against an inhibitory cytotoxic T-lymphocyte-associated antigen 4 receptor on T cells. It is associated with a range of immune-related toxicities. Sweet's syndrome in association with ipilimumab has been reported only briefly in the literature. However, neutrophilic infiltration has been seen in biopsies of patients with ipilimumab-associated enterocolitis. We report, in detail, the case of a woman with metastatic melanoma undergoing ipilimumab therapy. After the second cycle of immunotherapy, the patient presented with high-grade fever followed by a rash on her hands. No infectious etiology was elucidated after an extensive workup. Pathologic examination of the skin biopsy from the hands confirmed neutrophilic dermatosis. The patient was treated with systemic steroids achieving complete remission of the skin lesions. Physicians should be aware of Sweet's syndrome as a possible cutaneous side effect of ipilimumab therapy and be familiar with its management. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Miller E.A.,One Gustave L. Levy Place | Gopal R.,Mount Sinai School of Medicine | Valdes V.,New York University | Berger J.S.,New York University | And 2 more authors.
AIDS | Year: 2015

Objective: Plasma soluble CD40 ligand (sCD40L) is increased during HIV-1 infection, but it is unknown whether it circulates in monomeric or multimeric forms, and whether the circulating forms have differential effects on myeloid dendritic cell function and adaptive regulation. Design: sCD40L forms were measured in plasma samples from HIV-infected donors. The effects of sCD40L forms on dendritic cell function were measured in vitro. Methods: To delineate which forms of sCD40L are present in plasma from HIV-infected donors, immunoblots were performed following enrichment of plasma for medium and low-abundance proteins. Dendritic cells from seronegative donors were exposed to multiple forms of sCD40L prior to Toll-like receptor stimulation and dendritic cell function and adaptive regulation was assessed in vitro. Results: Monomeric and multimeric forms of sCD40L were identified in plasma from antiretroviral therapy-treated HIV-infected donors. Although monomeric and multimeric forms of sCD40L had differential effects on dendritic cell activation when given alone, both strongly suppressed secretion of the Th1 skewing cytokine, interleukin-12, upon subsequent Toll-like receptor stimulation. Furthermore, dendritic cells exposed to both monomeric and multimeric sCD40L induced regulatory T-cell formation and T-cell anergy. Conclusion: Elevated sCD40L during HIV infection impairs dendritic cell function, contributing to innate and adaptive immune dysfunction. Antiretroviral adjunctive therapies that decrease sCD40L may provide immune modulatory benefits. © 2015 Wolters Kluwer Health, Inc. All rights reserved.

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