Search results for "Melanocyte"
showing 10 items of 39 documents
Indicaxanthin from Opuntia Ficus Indica (L. Mill) impairs melanoma cell proliferation, invasiveness, and tumor progression.
2018
Abstract Background: A strong, reciprocal crosstalk between inflammation and melanoma has rigorously been demonstrated in recent years, showing how crucial is a pro-inflammatory microenvironment to drive therapy resistance and metastasis. Purpose: We investigated on the effects of Indicaxanthin, a novel, anti-inflammatory and bioavailable phytochemical from Opuntia Ficus Indica fruits, against human melanoma both in vitro and in vivo. Study Design and Methods: The effects of indicaxanthin were evaluated against the proliferation of A375 human melanoma cell line and in a mice model of cutaneous melanoma. Cell proliferation was assessed by MTT assay, apoptosis by Annexin V-Fluorescein Isothio…
The Amount of Melanin Influences p16 Loss in Spitzoid Melanocytic Lesions: Correlation With CDKN2A Status by FISH and MLPA.
2019
AIMS The risk assessment of spitzoid lesions is one of the most difficult challenges in dermatopathology practice. In this regard, the loss of p16 expression and the homozygous deletion of CDKN2A, have been pointed in the literature as reliable indicators of high risk. However, these findings are poorly reproducible, and the molecular bases underlying the loss of p16 expression remain unclear. We aimed to identify the underlying events causing loss of CDKN2A/p16 in spitzoid tumors. MATERIALS AND METHODS We evaluated the immunohistochemical expression of p16, and the presence of CDKN2A genetic alterations detected through fluorescence in situ hybridization (FISH) and multiplex ligation-depen…
Pathological modelling of pigmentation disorders associated with Hutchinson-Gilford Progeria Syndrome (HGPS) revealed an impaired melanogenesis pathw…
2018
AbstractHutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic disorder that leads to premature aging. In this study, we used induced pluripotent stem cells to investigate the hypopigmentation phenotypes observed in patients with progeria. Accordingly, two iPS cell lines were derived from cells from HGPS patients and differentiated into melanocytes. Measurements of melanin content revealed a lower synthesis of melanin in HGPS melanocytes as compared to non-pathologic cells. Analysis of the melanosome maturation process by electron microscopy revealed a lower percentage of mature, fully pigmented melanosomes. Finally, a functional rescue experiment revealed the direct role of progerin…
Migration of Melanoblasts into the Developing Murine Hair Follicle Is Accompanied by Transient c-Kit Expression
2002
Disruption of the c-Kit/stem cell factor (SCF) signaling pathway interferes with the survival, migration, and differentiation of melanocytes during generation of the hair follicle pigmentary unit. We examined c-Kit, SCF, and S100 (a marker for precursor melanocytic cells) expression, as well as melanoblast/melanocyte ultrastructure, in perinatal C57BL/6 mouse skin. Before the onset of hair bulb melanogenesis (i.e., stages 0–4 of hair follicle morphogenesis), strong c-Kit immunoreactivity (IR) was seen in selected non-mela-nogenic cells in the developing hair placode and hair plug. Many of these cells were S100-IR and were ultrastructurally identified as melanoblasts with migratory appearanc…
Evaluation of DNA ploidy and degree of DNA abnormality in benign and malignant melanocytic lesions of the skin using video imaging.
2000
BACKGROUND Making a morphologic distinction between benign and malignant melanocytic tumors of the skin is frequently difficult, especially because “gray zones” between these lesions often exist. DNA image cytometry as an adjuvant method for the diagnosis and prognostic prediction of premalignant lesions and malignant tumors of many other organs is already well established. The aim of this study was to determine whether DNA image cytometry is helpful in distinguishing benign from malignant melanocytic lesions and whether cytometry would give valid information with which to predict the prognoses associated with malignant melanomas. METHODS DNA image cytometry was performed on 127 benign and …
Immunoselection in vivo: independent loss of MHC class I and melanocyte differentiation antigen expression in metastatic melanoma
1997
Peptides derived from melanocyte differentiation antigens have been identified as targets for MHC class I-restricted cytolytic T lymphocytes (CTLs) in human melanoma Regression of antigen-expressing tumors as well as selection of antigen-loss variants in the presence of antigen-specific CTLs have previously been reported. In the present study, we determined the expression of the melanocyte differentiation antigens Melan A/MART-1 and tyrosinase by mRNA analysis and by immunohistochemical staining with the monoclonal antibodies (MAbs) A103 and T311. Co-expression of Melan A/MART-1 and tyrosinase was detected by both methods in 18/20 melanomas tested. However, immunohistochemistry provided add…
Spontaneous regression of multiple melanocytic nevi after melanoma: report of 3 cases.
2014
Complete spontaneous regression of multiple melanocytic nevi after melanoma is an extremely rare phenomenon. We report 3 cases of patients with a history of melanoma that showed regression of almost all melanocytic nevi over time. One of the patients had 2 simultaneous primary cutaneous melanomas without metastasis. In the other 2 patients, regression of the melanocytic nevi was seen after the development of metastasis in lymph nodes. These patients had spontaneously developed an efficient immune response against melanocytes, and they would represent paradigmatic examples of the spontaneous immune responses in melanoma patients. Better understanding of the mechanisms involved in the complet…
Apolipoprotein E Regulates Amyloid Formation within Endosomes of Pigment Cells.
2015
International audience; Accumulation of toxic amyloid oligomers is a key feature in the pathogenesis of amyloid-related diseases. Formation of mature amyloid fibrils is one defense mechanism to neutralize toxic prefibrillar oligomers. This mechanism is notably influenced by apolipoprotein E variants. Cells that produce mature amyloid fibrils to serve physiological functions must exploit specific mechanisms to avoid potential accumulation of toxic species. Pigment cells have tuned their endosomes to maximize the formation of functional amyloid from the protein PMEL. Here, we show that ApoE is associated with intraluminal vesicles (ILV) within endosomes and remain associated with ILVs when th…
Direct subphthalocyanine conjugation to bombesin vs. indirect conjugation to its lipidic nanocarrier
2016
International audience; Bombesin (BBN) was covalently bound to graftable subphthalocyanine (SubPc) or to a cholesterol derivative, a component of a liposome that encapsulates non-graftable SubPc. The latter bioconjugation approach was suitable to address the stability of SubPc and was achieved by copper-free click-chemistry on the outer-face of the liposome. Liposomes were purified (FPLC) and then analyzed in size (outer diameter about 60 nm measured by DLS). In vitro binding studies allowed to determine the IC50 13.9 nM for one component of the liposome, cholesterol, conjugated to BBN. Hence, azido- (or alkynyl-) liposomes give fluorophores with no reactive functional group available on th…
Clonal expansion of melan a-specific cytotoxic T lymphocytes in a melanoma patient responding to continued immunization with melanoma-associated pept…
2000
Peptides derived from human tumor antigens have been used in a number of clinical trials to induce specific immune responses against autologous tumors in cancer patients. Although favorable clinical results were observed in single patients, immune responses correlating with tumor regression were either not detected or in case of responses, the T-cell specificity was difficult to demonstrate. In this study, we analyzed antigen-specific T-cell responses induced in the skin and in peripheral blood lymphocytes (PBL) in an HLA-A2-positive melanoma patient. The patient showed major regression of metastatic melanoma under continued immunization with peptides derived from the melanocyte differentia…