The Novel Fusion Protein Melittin‐MIL‐2 Exhibits Strong Antitumor Immune Effect in Lung Adenocarcinoma Cell A549

Abstract

ABSTRACTIn previous studies, we developed a novel fusion protein named “melittin‐MIL‐2” which exhibited more anti‐tumor activity. However, it remains unclear whether melittin‐MIL‐2 possesses antitumor immune effect on lung adenocarcinoma. In this study, the immune effect and mechanism of melittin‐MIL‐2 inhibiting the growth and invasion of lung adenocarcinoma will be investigated, in order to provide novel perspectives for the immunotherapy of lung cancer. The results indicated that melittin‐MIL‐2 promoted T cell proliferation, enhanced NK cell cytotoxicity, and boosted IFN‐γ secretion in PBMCs. After melittin‐MIL‐2 stimulation, perforin expression and LAK/NK‐like killing activities of human PBMCs and NK cells were significantly enhanced. Melittin‐MIL‐2 is capable of hampering the development and proliferation of lung adenocarcinoma cell A549. ICAM‐1 and Fas expression in A549 cells exposed to melittin‐MIL‐2 rose significantly. The expression levels of TLR8 and VEGF in A549 cells decreased significantly after melittin‐MIL‐2 stimulation. In vivo, melittin‐MIL‐2 substantially impeded the growth of lung adenocarcinoma and formed an immune‐stimulating microenvironment locally in tumor tissues. In conclusion, the novel fusion protein melittin‐MIL‐2 exhibits strong anti‐tumor immune effect in lung adenocarcinoma cell A549 via activating the LFA‐1/ICAM‐1 and Fas/FasL pathways to enhance cytolytic activity, upregulating the secretion of IFN‐γ and perforin, and boosting LAK/NK‐like killing activities. Immuno‐effector cells and their secreted cytokines can form immune stimulation microenvironment locally in lung adenocarcinoma Lewis mice tissue.