Interleukin-38 promotes tumor growth through regulation of CD8+ tumor-infiltrating lymphocytes in lung cancer tumor microenvironment.

Interleukin (IL)-38 was discovered in 2001 and is a member of the IL-1 family of cytokines. IL-38 shows anti-inflammatory activity in several inflammatory diseases. In lung adenocarcinoma, we previously demonstrated that high IL-38 expression in tumor cells was associated with poor prognosis. However, the role of IL-38 in the tumor microenvironment has not been clarified. IL-38-plasmid-transfected Lewis lung carcinoma cells (LLC-IL38) and empty vector-transfected LLC cells (LLC-vector) were established. Cell proliferation in vitro and tumor growth in vivo were examined, and immunohistochemical staining was used to assess tumor-infiltrating lymphocytes (TILs). A CD8+ lymphocyte depletion model was established to show the association between IL-38 and CD8+ lymphocytes. Moreover, we examined the association between IL-38 expression and CD8+ TILs in human samples, analyzing immunohistochemical staining in 226 patients with radically resected lung adenocarcinoma. Tumor growth of LLC-IL38 in vivo was significantly increased compared with that of LLC-vector, although cell proliferation of LLC-IL38 in vitro was lower than that of LLC-vector. CD8+ TILs were significantly decreased in LLC-IL38 tumor compared with LLC-vector tumor. The difference in tumor growth between LLC-IL38 and LLC-vector became insignificant after depletion of CD8+ lymphocytes. In immunohistochemical staining in tissues from patients with lung adenocarcinoma, multivariate analysis showed high IL-38 expression was an independent negative predicter of high density of CD8+ TILs. We demonstrated that high IL-38 expression in tumor cells was significantly associated with reduction of CD8+ TILs and tumor progression. These results suggest that IL-38 could be a therapeutic target for lung cancer.

Citation

Fumihiko Kinoshita, Tetsuzo Tagawa, Takaki Akamine, Kazuki Takada, Yuichi Yamada, Yuka Oku, Keisuke Kosai, Yuki Ono, Kensuke Tanaka, Sho Wakasu, Taro Oba, Atsushi Osoegawa, Mototsugu Shimokawa, Yoshinao Oda, Tomoaki Hoshino, Masaki Mori. Interleukin-38 promotes tumor growth through regulation of CD8+ tumor-infiltrating lymphocytes in lung cancer tumor microenvironment. Cancer immunology, immunotherapy : CII. 2021 Jan;70(1):123-135

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PMID: 32653939

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