RESUMO
Exosomes (small extracellular vesicles: EVs) have attracted increasing attention from basic scientists and clinicians since they play important roles in cell-to-cell communication in various biological processes. Various features of EVs have been elucidated regarding their contents, generation and secretion mechanisms, and functions in inflammation, regeneration, and cancers. These vesicles are reported to contain proteins, RNAs, microRNAs, DNAs, and lipids. Although the roles of individual components have been rigorously studied, the presence and roles of glycans in EVs have rarely been reported. In particular, glycosphingolipids in EVs have not been investigated to date. In this study, the expression and function of a representative cancer-associated ganglioside, GD2, in malignant melanomas was investigated. Generally, cancer-associated gangliosides have been shown to enhance malignant properties and signals in cancers. Notably, EVs derived from GD2-expressing melanomas enhanced the malignant phenotypes of GD2-negative melanomas, such as cell growth, invasion, and cell adhesion, in a dose-dependent manner. The EVs also induced increased phosphorylation of signaling molecules such as EGF receptor and focal adhesion kinase. These results suggest that EVs released from cancer-associated ganglioside-expressing cells exert many functions that have been reported as a function of these gangliosides and regulate microenvironments, including total aggravation of heterogeneous cancer tissues, leading to more malignant and advanced cancer types.
Assuntos
Vesículas Extracelulares , Gangliosídeos , Melanoma , Microambiente Tumoral , Humanos , Vesículas Extracelulares/metabolismo , Gangliosídeos/análise , Gangliosídeos/metabolismo , Melanoma/metabolismo , Melanoma/patologia , Linhagem Celular TumoralRESUMO
This study describes the genome sequence of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain detected in the nasopharyngeal swab sample of a coronavirus disease 2019 (COVID-19) patient from the southeastern Khagrachari District of Bangladesh.
RESUMO
Some gangliosides, sialic acid-containing glycosphingolipids, have been considered as tumor-associated antigens. GD1α or a GD1α synthase gene ST6GalNAc5 was reported to be involved in the metastasis of murine lymphomas or human breast cancers, respectively. But expression patterns of 0-series gangliosides GD1α and its precursor GM1b in human cancers have not yet been investigated mainly due to lack of specific antibodies. We established specific monoclonal antibodies (mAbs) reactive with GD1α or GM1b using gangliosides from brain tissues of GM3 synthase (St3gal5)-deficient mice as immunogens. We used GM2/GD2 synthase (B4galnt1)-deficient mice to immunize by liposomes embedded with GD1α or acidic glycolipid fractions from brain of St3gal5-deficient mice. Specificities of established mAbs as analyzed by enzyme-linked immunosorbent assay and thin-layer chromatography-immunostaining were very high among various gangliosides. Increased expression of GD1α and reduced GM1b in the St6galnac5 cDNA-transfected RAW117 cell line also substantiated the specificities of two mAbs. Then, we analyzed expression of GD1α and GM1b, and of relevant glycosyltransferase genes in various human cancer cell lines using generated anti-GD1α mAb 122 or anti-GM1b mAb MR155A-7. A few human cancer cell lines showed significant expression of these gangliosides with reasonable expression of relevant glycosyltransferase genes.
Assuntos
Gangliosídeo G(M1)/análogos & derivados , N-Acetilgalactosaminiltransferases/genética , Sialiltransferases/genética , Animais , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Antígenos de Neoplasias/genética , Linhagem Celular Tumoral , Gangliosídeo G(M1)/biossíntese , Gangliosídeo G(M1)/genética , Gangliosídeo G(M1)/metabolismo , Gangliosídeos/genética , Gangliosídeos/metabolismo , Regulação Enzimológica da Expressão Gênica , Glicoesfingolipídeos/genética , Glicoesfingolipídeos/imunologia , Glicoesfingolipídeos/metabolismo , Humanos , Camundongos , Camundongos Knockout , N-Acetilgalactosaminiltransferases/metabolismo , Metástase Neoplásica , Sialiltransferases/metabolismoRESUMO
We previously demonstrated that focal adhesion kinase (FAK), p130Cas and paxillin are crucially involved in the enhanced malignant properties under expression of ganglioside GD3 in melanoma cells. Therefore, molecules existing in the GD3-mediated signaling pathway could be considered as suitable targets for therapeutic intervention in malignant melanoma. The aim of this study was to determine whether blockade of p130Cas and/or paxillin by RNAi suppresses melanoma growth. We found a suitable dose (40 µM siRNA, 25 µl/tumor) of the siRNA to suppress p130Cas in the xenografts generated in nu/nu mice. Based on these results, we performed intratumoral (i.t.) treatment with anti-p130Cas and/or anti-paxillin siRNAs mixed with atelocollagen as a drug delivery system in a xenograft tumor of a human melanoma cell line, SK-MEL-28. Mixture of atelocollagen (1.75%) and an siRNA (500 or 1000 pmol/tumor) was injected into the tumors every 3 days after the first injection. An siRNA against human p130Cas markedly suppressed tumor growth of the xenograft in a dose-dependent manner, whereas siRNA against human paxillin slightly inhibited the tumor growth. A control siRNA against firefly luciferase showed no effect. To our surprise, siRNA against human p130Cas (500 or 1000 pmol/tumor) combined with siRNA against human paxillin dramatically suppressed tumor growth. In agreement with the tumor suppression effects of the anti-p130Cas siRNA, reduction in Ki-67 positive cell number as well as in p130Cas expression was demonstrated by immunohistostaining. These results suggested that blockade of GD3-mediated growth signaling pathways by siRNAs might be a novel and promising therapeutic strategy against malignant melanomas, provided signaling molecules such as p130Cas and paxillin are significantly expressed in individual cases. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.