Overcoming cancer-associated fibroblast-induced immunosuppression by anti-interleukin-6 receptor antibody
Noriyuki Nishiwaki, Kazuhiro Noma, Toshiaki Ohara, Tomoyoshi Kunitomo, Kento Kawasaki, Masaaki Akai, Teruki Kobayashi, Toru Narusaka, Hajime Kashima, Hiroaki Sato, Satoshi Komoto, Takuya Kato, Naoaki Maeda, Satoru Kikuchi, Shunsuke Tanabe, Hiroshi Tazawa, Yasuhiro Shirakawa, Toshiyoshi Fujiwara
Abstract
Cancer-associated fibroblasts (CAFs) are a critical component of the tumor microenvironment and play a central role in tumor progression. Previously, we reported that CAFs might induce tumor immunosuppression via interleukin-6 (IL-6) and promote tumor progression by blocking local IL-6 in the tumor microenvironment with neutralizing antibody. Here, we explore whether an anti-IL-6 receptor antibody could be used as systemic therapy to treat cancer, and further investigate the mechanisms by which IL-6 induces tumor immunosuppression. In clinical samples, IL-6 expression was significantly correlated with α-smooth muscle actin expression, and high IL-6 cases showed tumor immunosuppression. Multivariate analysis showed that IL-6 expression was an independent prognostic factor. In vitro, IL-6 contributed to cell proliferation and differentiation into CAFs. Moreover, IL-6 increased hypoxia-inducible factor 1α (HIF1α) expression and induced tumor immunosuppression by enhancing glucose uptake by cancer cells and competing for glucose with immune cells. MR16-1, a rodent analog of anti-IL-6 receptor antibody, overcame CAF-induced immunosuppression and suppressed tumor progression in immunocompetent murine cancer models by regulating HIF1α activation in vivo. The anti-IL-6 receptor antibody could be systemically employed to overcome tumor immunosuppression and improve patient survival with various cancers. Furthermore, the tumor immunosuppression was suggested to be induced by IL-6 via HIF1α activation.