The Preliminary Study Of IL-33 Expression In Cancer And Its Function On Inhibiting Tumor

Objective:To investigate the expression of IL-33 in lung cancer and breast cancer and observe its relationship with pathology and clinical indicators. To establish the transfectant 4T1-IL-33 stably secreting mouse mature IL-33 protein and analyze the anti-tumor role of IL-33 expressed by 4T1-IL-33 in tumor microenvironment.Methods: The lung cancer tissues and distal normal lung tissues were obtained by surgical removal from clinically confirmed 33 patients with lung cancer. Based on extracting total RNA from lung cancer and para carcinoma with Trizol, the expression of IL-33 was determined by the method of QRT-PCR. In addition, IL-33 expression in breast cancer was analyzed based on the GEO database. The gene fragment encoding the mature peptide(S109 to I266) sequence of murine IL-33 was amplified based on RT-PCR from mouse lung RNA. Then IL-33 expression construct was generated by fusing the the fragment encoding human CD8α signal sequence to the 5’ end of IL-33 sequence, subsequently ligated into pc DEF3 vector. The recombinant vector was transfected into 4T1 cells with Lipfect AMINETM 2000, and the cells were further selected with G418.Expression levels of IL-33 in the transfectant supernatant by were measured by ELISA assay. In vitro, the capacity of IL-33 stimulating CD8+ T cell secreting IFN-g was measured by ELISA assay. The growth and proliferation of transfectants were determined by cell counting with Trypan staining and by flow cytometry respectively.Results: The results showed that expression of IL-33 m RNA in para carcinoma was higher than cancer(P=0.01). The stable expression of IL-33 in the supernatant of the transfected cell line was identified by ELISA assay. There are no differences of growth and proliferation between 4T1-vec and 4T1-IL-33 cell lines(P>0.05). In vitro, IL-33 can obviously promote effector CD8+ T cell to secret IFN-g(P<0.05). In vivo, IL-33 secreted in the tumor microenvironment by 4T1-IL-33 transfectant can significantly inhibit tumor growth and metastasis(P<0.01).Conclusion: IL-33 expression significantly decreased in cancer compared with para carcinoma, suggesting that IL-33 in the tumor microenvironment possibly effect on anti-tumor response and its downregulation may contribute to tumorigenesis. The transfectant 4T1-IL-33 stably secreting mouse IL-33 has been established and IL-33 expressed in the tumor microenvironment can prominently inhibit tumor growth and metastasis.