Expression of interleukin-17 in experimental models of murine mammary carcinoma

Abstract

Objective To explore the impact of interleukin (IL) -17 expression on tumor growth in experimental models of murine mammary carcinoma and potential mechanisms. Methods Two murine cell lines, MA782/5S28102 and 4T1 were used to establish experimental models of murine mammary carcinoma. The IL-17 expression in tumor tissues derived from MA782-bearing mice or 4T1-bearing mice was detected in early and late stages of the tumor by Western blotting. The tumor cells and tumor-infiltrated-lymphocytes were separated from tumor tissues and cultured for 5 days with stimulation of PMA, anti-CD3 antibody and anti-CD28 antibody. The supernatants of culture media of stimulated tumor cells or tumor-infiltrated-lymphocytes were harvested and tested for IL-17 concentration by enzyme linked immunosorbent assay (ELISA). To evaluate the effect of IL-17 on the proliferation of tumor cells, 4T1 cells were culture in media with or without IL-17 and the cell number was counted on the day 5. For ire vivo assay, 4T1-bearing mice were injected with IL-17 or culture media via tail vein, and the tumor volume was measured. To assay the angiogenesis, the tumor tissues from 4T1-bearing mice with or without injection of IL-17 were stained with anti-CD31 antibody by immunohistochemistry. Results The IL-17 expression was significantly higher in late stage than in early stage of tumor in two experimental models. The tumor expression of IL-17 was secreted by tumor infiltrated lymphocytes (P ＜0.01). IL-17 could not increase the generation of tumor cells in vitro (1. 11 ±0. 11, 1. 28 ±0. 21 ,P ＞0. 05). But IL-17, injected into 4T1 -bearing mice, markedly enhanced in vivo tumor growth and significantly increased tumor vascularity (35. 79 ±9. 49, 13. 52 ±3. 55,P ＜0.01). Conclusion IL-17 in tumor tissue probably promotes tumor growth through enhancing angiogenesis. Key words: Mammary carcinoma; IL-17; Angiogenesis