An Anti‐GD2 Monoclonal Antibody Enhances Apoptotic Effects of Anti‐cancer Drugs against Small Cell Lung Cancer Cells via JNK (c‐Jun Terminal Kinase) Activation

Abstract

Small cell lung cancer (SCLC) cell lines specifically express ganglioside GD2, and anti-GD2 monoclonal antibodies (mAbs) caused suppression of cell growth and induced apoptosis of SCLC cells with single use. Here, enhancement of the cytotoxic effects of various anti-cancer drugs with an anti-GD2 mAb was demonstrated. The cytotoxicity of all six drugs examined was markedly enhanced, i.e. 2.4-7.8-fold increase of cell sensitivity in terms of IC 50 . In particular, the combination of cisplatin (CDDP) with an anti-GD2 mAb resulted in prominent enhancement of cytotoxicity even in low-moderate GD2-expressing lines. The anti-GD2 mAb induced weak activation of c-Jun terminal kinase (JNK) in SCLC cells, and all anti-cancer drugs also induced its activation to various degrees. When CDDP and an anti-GD2 mAb were used together, significantly stronger JNK activation was observed corresponding to the cytotoxic effects, suggesting that synergistic phosphorylation of JNK with two reagents induced prominent apoptosis. The essential role of JNK in the induction of SCLC apoptosis with CDDP and anti-GD2 mAb was confirmed by experiments with a JNK inhibitor, curcumin. These results suggest that anti-GD2 mAbs would be very efficient in combination with anti-cancer drugs, both to achieve SCLC-specific cytotoxicity and to enhance its magnitude. Key words: Apoptosis -Small cell lung cancer -Chemotherapy -JNK -GD2Gangliosides are enriched in nervous tissues of vertebrates 1) and their expression is spatio-temporally regulated.2) In human malignant tumor cells, neuroectodermderived tumor cells such as melanomas, neuroblastomas, and gliomas frequently express characteristic gangliosides for individual tumor types.3-6) Sarcomas, 7) gastric cancers, 8,9) T cell leukemias [10][11][12] and small cell lung cancer (SCLC) cells 13) also express specific gangliosides. Specific monoclonal antibodies (mAbs) to these tumor-associated ganglioside antigens have been utilized for diagnosis, 14,15) prediction of the prognosis, 16,17) and detection of residual tumors.18) In particular, anti-ganglioside mAbs have been tried for immunotherapy of melanomas 19,20) and neuroblastomas. 21)During the early stage of mAb application, anti-GD3 mAb R24 was used for the first time in the treatment of recurrent melanomas, and showed the ability to reduce the tumor size or halt the progression.19) Anti-GD2 mAb was also applied in the treatment of neuroblastomas to extend remission.22) Moreover, a human mAb reactive with GD2 was tried for cutaneous melanomas with some effects. 20)However, further development of antibody therapy has not been successful mainly due to xenogeneic immunogenicity of mouse antibodies and poor penetration of antibodies into tumor tissues.Recently, application of mAbs for the treatment of various cancers has been re-evaluated based on the progress in recombinant molecular technology and protein engineering with site-directed mutagenesis. Anti-c-erbB2/HER2/neu mAb was used in the therapy of advanced stages of breast cancers 23) and anti-CD20 mAb ...

Binding Activities and Antitumor Properties of a New Mouse/Human Chimeric Antibody Specific for GD2 Ganglioside Antigen

“…Direct apoptotic induction with anti-GD2 mouse mAbs has thus far been reported with GD2-expressing small cell lung carcinoma cell lines (11). Anti-GD2 mAbs binding on the cell surface are thought to cause conformational changes in integrin molecules, leading to the disruption of cell-matrix interactions with subsequent dephosphorylation of focal adhesion kinases (40). In this study, EL4 lymphoma cell apoptosis induced by anti-GD2 mAbs was mainly observed with the murine IgG 3 anti-GD2 60C3 antibody, whereas chimeric c.60C3 had a weak effect at the highest concentration (Fig.…”

“…Another mechanism contributing to the antitumor effect upon passive immunotherapy with anti-GD2 mAbs involves cell death induction without immune effector mechanism (11,40). Apoptosis induced by anti-GD2 mAbs is very interesting because this mechanism may be very important in the treatment of solid tumors that have evolved complex mechanisms to protect themselves from CDC and ADCC (41).…”

GD2 ganglioside specific antibody treatment downregulates PI3K/Akt/mTOR signaling network in human neuroblastoma cell lines

“…The mechanisms of the anti-proliferative effects of the antibodies are only partially elucidated. In small cell lung cancer cell cultures anti-GD2 ganglioside monoclonal antibodies induced apoptosis through reduction of the phosphorylation levels of focal adhesion kinase (FAK) and the activation of p38 (6) as well as activation of c-Jun N terminal kinase (JNK) (7). Moreover, the anti-GD2 ganglioside mAbs were very efficient in combination with anticancer drugs to exert enhanced cytotoxicity against the afore-mentioned cells (7).…”

“…Several studies have evidenced that GD2-specific antibodies inhibit tumor growth without involvement of the immune system (6)(7)(8). The mechanisms of the anti-proliferative effects of the antibodies are only partially elucidated.…”

“…In small cell lung cancer cell cultures anti-GD2 ganglioside monoclonal antibodies induced apoptosis through reduction of the phosphorylation levels of focal adhesion kinase (FAK) and the activation of p38 (6) as well as activation of c-Jun N terminal kinase (JNK) (7). Moreover, the anti-GD2 ganglioside mAbs were very efficient in combination with anticancer drugs to exert enhanced cytotoxicity against the afore-mentioned cells (7). Our studies showed that the anti-GD2 14G2a mAb decreases survival of IMR-32 human neuroblastoma cells in a dose-dependent manner through induction of apoptosis and also exerts a synergistic effect with doxorubicin and topotecan in killing IMR-32 cells in culture (8).…”