ABSTRACT
BACKGROUND: Connexins form the intercellular channels of the gap junction and play an integral part in a variety of biological functions, such as maintaining tissue homeostasis, cell growth control, and development. Previously it was demonstrated that the expression of connexin 26 (Cx26) can increase the metastatic potential of mouse melanoma cells. The objective of the study was to investigate the role Cx26 plays in the metastasis of human melanoma cells, focusing on the communication between melanoma cells and endothelial cells. METHODS: Immunostaining was used to examine Cx26 expression in the melanoma lesions and in the endothelial cells around the melanoma cell nests. In all, 33 melanomatous tissue samples from 16 patients were studied, as well as nevocellular nevus (NCN) and normal skin samples. Cx26 mRNA and protein expression was also examined in the cultured endothelial cells. A dye-transfer assay was performed to examine gap junction formation between melanoma cells and endothelial cells. RESULTS: Immunohistochemistry demonstrated that Cx26 was clearly expressed by the endothelial cells of the small vessels surrounding the melanoma cell nests as well as the melanoma cells. Cx26 mRNA and protein expression was detected in cultured endothelial cells. In a coculture system with human malignant melanoma cell line (HMY-1) and endothelial cells (HMVEC), immunohistochemistry indicated Cx26 expression in both types of cells and dye-transfer assay demonstrated dye-coupling from HMY-1 into HMVEC. CONCLUSIONS: Cx26 may contribute to the metastasis of melanoma by facilitating communication between melanoma cells and their surrounding endothelial cells.
Subject(s)
Connexins/metabolism , Melanoma/pathology , Skin Neoplasms/pathology , Adult , Aged , Cell Line , Cell Line, Tumor , Cell Membrane/metabolism , Connexin 26 , Connexin 30 , Connexins/genetics , Connexins/physiology , Endothelial Cells/cytology , Endothelial Cells/metabolism , Female , Gene Expression Regulation, Neoplastic , Humans , Immunohistochemistry , Male , Melanoma/genetics , Melanoma/metabolism , Middle Aged , Neoplasm Metastasis , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Skin Neoplasms/genetics , Skin Neoplasms/metabolismABSTRACT
Severe hypersensitivity to mosquito bites (HMB) is characterized by intense local skin reactions and systemic symptoms such as high fever, lymphadenopathy, and hepatosplenomegaly. Patients with HMB often have natural killer (NK) cell lymphocytosis associated with Epstein-Barr virus (EBV) infection. Here we investigated whether mosquito bites have any influence on the oncogenesis of EBV-infected NK cells. We examined six HMB patients with EBV-infected NK cell lymphocytosis. We first demonstrated that CD4+ T cells, but not NK cells, proliferated well in response to mosquito salivary gland extracts (SGE), especially to SGE of Aedes albopictus. When NK cells were cocultured with autologous CD4+ T cells stimulated by mosquito SGE, the expression of viral oncogene latent membrane protein 1 (LMP1) was remarkably enhanced. Next, we stimulated mononuclear cells of the patients with mosquito SGE, and NK cell counts were monitored for 28 d. The counts changed little from initial levels in the culture with mosquito SGE, whereas they decreased steadily in the culture without the extracts. Furthermore, we detected LMP1 mRNA in the skin lesion induced by mosquito SGE. These results suggest that mosquito bites can induce expression of the viral oncogene LMP1 in NK cells via mosquito antigen-specific CD4+ T cells, which is involved in the oncogenesis of NK cells in vivo.
