S. Wang1, Y. Wang1, J. Wang2, X. Zhang3, and J. Wang3; 1The Fourth Hospital of Hebei Medical University, Shijiazhuang, China, 2the Fourth Hospital of Hebei Medical University, Shijiazhuang, China, 3Fourth Hospital of Hebei Medical University, Shijiazhuang, China
Purpose/Objective(s): This study aims to develop an mRNA-LNP (lipid nanoparticle) vaccine targeting the HER2
site and to explore its antitumor effect in combination with radiotherapy in a mouse model bearing HER2-overexpressing LLC (HER2-LLC) tumors. The study focuses on designing and preparing an efficient HER2-targeted mRNA-LNP (HER2-mRNA-LNP) vaccine, evaluating its immunogenicity in the HER2-LLC mouse model, and investigating the synergistic effects of combining the HER2-mRNA-LNP vaccine with radiotherapy. Materials/Methods:
The HER2-mRNA-LNP was prepared, and a stable cell line of HER2-LLC was established and verified. After vaccine injection, antibody levels in mouse serum were measured by ELISA. Flow cytometry was used to analyze the proportion of immune cells in mouse spleen cells. ELISA was performed to detect cytokines in splenic lymphocytes, and a cell counting kit assay was used to measure the killing rate of splenic lymphocytes against tumor cells. Flow cytometry was used to analyze the proportion of immune cells in tumor tissues. Immunohistochemistry was employed to analyze the expression of HER2 antigen and the changes in tumor proliferative capacity. HE was performed on liver, lung, and heart tissues, and the complete blood count, liver and kidney function tests, as well as myocardial enzyme profile tests were conducted on blood samples to evaluate the safety of the vaccine.
Results:
The particle size distribution and zeta potential of LNPs, the encapsulation efficiency of the HER2-mRNA-LNP indicate that it is of good quality and has stable properties. The results of WB and QPCR verified the successful overexpression of HER2 in LLC cells. In the HER2-LLC model, the HER2-mRNA-LNP vaccine exhibited significant tumor-inhibiting effects and showed a synergistic anti-tumor effect when combined with radiotherapy. The changes in the composition of immune cells in tumors and spleens and the changes of cytokines suggest that the vaccine activates the systemic immune response and alters the tumor immune microenvironment. Moreover, the combination with radiotherapy can enhance the body's immune response. In the HER2-mRNA-LNP group, no abnormalities were observed in HE staining, routine blood tests, liver and kidney function tests, or myocardial enzyme profile tests, indicating that the vaccine has good safety. Immunohistochemistry showed significant differences in tumor proliferation.
Conclusion:
The HER2-mRNA-LNP vaccine can effectively inhibit tumor growth in the HER2-LLC mouse model and produce a synergistic anti-tumor effect when combined with radiotherapy. This vaccine exerts its anti-tumor effects by improving the tumor immune microenvironment and activating the body's immune response.
