Potential therapeutic role of interleukin 9 in a mouse lung cancer model

Abstract

Introduction: Lung cancer is still the leading cause of cancer-related death. Mounting evidence indicated that interleukin 9 (IL-9) was linked to cancer. However, its role in lung cancer is still controversial. In this study, we aimed to explore the therapeutic role of IL-9 in lung cancer and to elucidate its mechanism. Methods: Mouse Lewis lung carcinoma (LLC) cells and human lung cancer cell lines (H1975, A549, HCC827) were purchased from ATCC. Western blot was used to detect the IL-9 receptor expression. MTT assay was conducted to explore the effect of IL-9 on human lung cancer cell lines. Lewis lung carcinoma mouse model was established by subcutaneous injection of 500000 LLC cells. At day 7, the mice were randomised and divided into control and IL-9 group. In IL-9 arm, mice were treated with IL-9 intraperitoneally (50 ng/mouse, 3 times/ week). The body weight of mice and tumour volume were measured every other day. Results: Interleukin 9 receptor was found in all human lung cancer cell lines, but not in LLC. Interleukin 9 inhibited cell proliferation in human lung cancer cell lines. After incubation of 50 ng/mL IL-9 for 48 hours, about 20% to 40% reduction of cell growth was observed. Moreover, IL-9 suppressed the tumour growth in LLC mouse model. The relative tumour volume in the IL-9 treatment arm was 69% that of the control group at the end of treatment (P=0.0295). Conclusion: Interleukin 9 slightly inhibited growth of human lung cancer cell lines only possibly due to endogenous expression of IL-9 receptor in those cell lines. In contrast, IL-9 suppressed tumour growth in LLC mouse model. The underlying mechanisms remain to be elucidated. Acknowledgement This study was supported by YC Chan Scientist Award 2019 and Donation from Lifestyle International Holdings Limited.