Ganglioside GD2 in reception and transduction of cell death signal in tumor cells

Abstract

BackgroundGanglioside GD2 is expressed on plasma membranes of various types of malignant cells. One of the most promising approaches for cancer immunotherapy is the treatment with monoclonal antibodies recognizing tumor-associated markers such as ganglioside GD2. It is considered that major mechanisms of anticancer activity of anti-GD2 antibodies are complement-dependent cytotoxicity and/or antibody-mediated cellular cytotoxicity. At the same time, several studies suggested that anti-GD2 antibodies are capable of direct induction of cell death of number of tumor cell lines, but it has not been investigated in details. In this study we investigated the functional role of ganglioside GD2 in the induction of cell death of multiple tumor cell lines by using GD2-specific monoclonal antibodies.MethodsExpression of GD2 on different tumor cell lines was analyzed by flow cytometry using anti-GD2 antibodies. By using HPTLC followed by densitometric analysis we measured the amount of ganglioside GD2 in total ganglioside fractions isolated from tumor cell lines. An MTT assay was performed to assess viability of GD2-positive and -negative tumor cell lines treated with anti-GD2 mAbs. Cross-reactivity of anti-GD2 mAbs with other gangliosides or other surface molecules was investigated by ELISA and flow cytometry. Inhibition of GD2 expression was achieved by using of inhibitor for ganglioside synthesis PDMP and/or siRNA for GM2/GD2 and GD3 synthases.ResultsAnti-GD2 mAbs effectively induced non-classical cell death that combined features of both apoptosis and necrosis in GD2-positive tumor cells and did not affect GD2-negative tumors. Anti-GD2 mAbs directly induced cell death, which included alteration of mitochondrial membrane potential, induction of apoptotic volume decrease and cell membrane permeability. This cytotoxic effect was mediated exclusively by specific binding of anti-GD2 antibodies with ganglioside GD2 but not with other molecules. Moreover, the level of GD2 expression correlated with susceptibility of tumor cell lines to cytotoxic effect of anti-GD2 antibodies.ConclusionsResults of this study demonstrate that anti-GD2 antibodies not only passively bind to the surface of tumor cells but also directly induce rapid cell death after the incubation with GD2-positive tumor cells. These results suggest a new role of GD2 as a receptor that actively transduces death signal in malignant cells.

Ganglioside as a Therapy Target in Various Types of Cancer

“…Tumor cells protect themselves against immune cells using immunosuppressive factors, for example tumor surrounding inhibitors inhibit infiltrating function of lymphocytes (Elgert et al,1998;Doronin et al, 2014). one of classes of immunosuppressant molecules that may play a role in tumor progression are Gangliosides (Doronin et al, 2014).…”

“…More importantly, Gangliosides exhibits the ability to connect and interact with a variety of proteins, including signaling molecules present in the tumor environment. In addition, they are able to connect to other cell membranes leading to messaging or communicating with healthy cells (Doronin et al, 2014;Boligan et al, 2015).…”

“…For example, increased levels of GD2 and GM3 were found in serum analyses of patients with Neuroblastoma, retinoblastoma and hepatoma. Several reports suggest that the gangliosides like GD1a, GD1b, GD3 and GM3 help tumor for escaping from the immune system (Battula et al, 2012;Doronin et al, 2014;Krengel and Bousquet, 2014). The role of Tumor Gangliosides shown in Figure 1.…”

“…Profile Change of Gangliosides in cultured cells has shown its role in regulating cell proliferation and differentiation (Fukumoto et al, 2000). Various types of tumors express glycosphingo lipid antigens such as gangliosides that are present in many tumors and detectable with the monoclonal antibody (Doronin et al, 2014).…”

“…Gangliosides show different effects on tumor as following: Effect on metastasis and angiogenesis of tumor, regulation of cell motility and signaling, immune suppression (Zeng et al, 2000;Doronin et al, 2014) …”