Cetuximab intensifies the ADCC activity of NK cells in nude mice xenograft colorectal cancer model

【作者】 郑秋红； 李雪春； 陈珊珊；

【机构】 福建省肿瘤医院； 福建省肿瘤生物治疗重点实验室；

【摘要】 Backgound: Colorectal cancer is the fifth leading cause of cancer death in China, and the 5-year survival rate remains poor for patients with recurrence or metastasis disease. There were some novel achievements in the prognosis of patients with advanced coloretal cancer in the past decades, immunotherapy stategy based on monoclonal antibodies is one of them. Besides, adoptive transfer of NK cells is also an attractive way to eliminate metastasis of colorectal cancer. However, accumuating data from clinical study indicate that when used as a monotherapy, metastatic colorectal cancer showed limited responses to cetuximab, meanwhile, the adoptive NK cell therapy also undergoing some limitations such as the immunosuppressive environment of colorectal cancer. The combination of NK cell therapy with antibody-based immunotherapy would be a potential effective way to enhance the antitumor activity towards metastasis colorectal cancer. Objective: To observe the antitumor activity of Cetuximab, the anti-EGFR monoclonal antibody, combined with NK cells in nude mice xenograft colorectal cancer models with different EGFR expression, and explore the ADCC activity of NK cells with or without cetuximab in vivo. Methods:The nude mice xenograft colorectal cancer models were established by subcutaneous injecting LOVO(EGFR+++) and SW620(EGFR-) cells. Then they were randomly divided into 6 groups: PBS, Cetuximab, hI g G, NK cells, h Ig G plus NK cells and Cetuximab plus NK cells. The ADCC antitumor activity was evaluated in the colorectal cancer models by the following methods. Tumor volume was measured and tumor growth curve was drawn during the treatment. All the mice were sacrificed 3 days after the end of treatment, tumor weigh were measured and the antitumor rate were evaluated. Pathological changes of tumor were analyzed by immunohistochemistry and TUNEL staining. Results: Immunohistochemistry confirmed that the LOVO cell was EGFR positive(+++) and SW620 cell was EGFR negative(-), indicating that LOVO or SW620 cells transplanted into nude mice kept their EGFR expression biological characteristics. Cetuximab plus NK cells group showed the greatest tumor inhibitory effect towards LOVO xenograft tumor models compared with the control groups(the PBS and h Ig G group)(P<0.01), while single Cetuximab or single NK cell group showed lower tumor inhibition effect than it(P<0.05). However, the combination of Cetuximab and NK cells did not show stronger tumor inhibitory effect against SW620 xenograft tumor when compared with the efficiency of single NK cells(P>0.05). Conclusion: Cetuximab could intensify the ADCC antitumor activity of NK cells towards xenograft colorectal cancer, and the activity was correlated with the level of EGFR expression. The combination of Cetuximab and NK cells may be a potential immunotherapy for advanced coloretal cancer patients with high EGFR expression, the level of EGFR expression on the tumor cells could be a prediction index for the efficacy of this therapy.更多还原

【Abstract】 Backgound: Colorectal cancer is the fifth leading cause of cancer death in China, and the 5-year survival rate remains poor for patients with recurrence or metastasis disease. There were some novel achievements in the prognosis of patients with advanced coloretal cancer in the past decades, immunotherapy stategy based on monoclonal antibodies is one of them. Besides, adoptive transfer of NK cells is also an attractive way to eliminate metastasis of colorectal cancer. However, accumuating data from clinical study indicate that when used as a monotherapy, metastatic colorectal cancer showed limited responses to cetuximab, meanwhile, the adoptive NK cell therapy also undergoing some limitations such as the immunosuppressive environment of colorectal cancer. The combination of NK cell therapy with antibody-based immunotherapy would be a potential effective way to enhance the antitumor activity towards metastasis colorectal cancer. Objective: To observe the antitumor activity of Cetuximab, the anti-EGFR monoclonal antibody, combined with NK cells in nude mice xenograft colorectal cancer models with different EGFR expression, and explore the ADCC activity of NK cells with or without cetuximab in vivo. Methods:The nude mice xenograft colorectal cancer models were established by subcutaneous injecting LOVO(EGFR+++) and SW620(EGFR-) cells. Then they were randomly divided into 6 groups: PBS, Cetuximab, hI g G, NK cells, h Ig G plus NK cells and Cetuximab plus NK cells. The ADCC antitumor activity was evaluated in the colorectal cancer models by the following methods. Tumor volume was measured and tumor growth curve was drawn during the treatment. All the mice were sacrificed 3 days after the end of treatment, tumor weigh were measured and the antitumor rate were evaluated. Pathological changes of tumor were analyzed by immunohistochemistry and TUNEL staining. Results: Immunohistochemistry confirmed that the LOVO cell was EGFR positive(+++) and SW620 cell was EGFR negative(-), indicating that LOVO or SW620 cells transplanted into nude mice kept their EGFR expression biological characteristics. Cetuximab plus NK cells group showed the greatest tumor inhibitory effect towards LOVO xenograft tumor models compared with the control groups(the PBS and h Ig G group)(P<0.01), while single Cetuximab or single NK cell group showed lower tumor inhibition effect than it(P<0.05). However, the combination of Cetuximab and NK cells did not show stronger tumor inhibitory effect against SW620 xenograft tumor when compared with the efficiency of single NK cells(P>0.05). Conclusion: Cetuximab could intensify the ADCC antitumor activity of NK cells towards xenograft colorectal cancer, and the activity was correlated with the level of EGFR expression. The combination of Cetuximab and NK cells may be a potential immunotherapy for advanced coloretal cancer patients with high EGFR expression, the level of EGFR expression on the tumor cells could be a prediction index for the efficacy of this therapy.更多还原