Crosstalk between cancer-associated fibroblasts and immune cells in peritoneal metastasis: inhibition in the migration of M2 macrophages and mast cells by Tranilast

Abstract

Background The role of tumor–stroma interactions in tumor immune microenvironment (TME) is attracting attention. We have previously reported that cancer-associated fibroblasts (CAFs) contribute to the progression of peritoneal metastasis (PM) in gastric cancer (GC), and M2 macrophages and mast cells also contribute to TME of PM. To elucidate the role of CAFs in TME, we established an immunocompetent mouse PM model with fibrosis, which reflects clinical features of TME. However, the involvement of CAFs in the immunosuppressive microenvironment remains unclear. In this study, we investigated the efficacy of Tranilast at modifying this immune tolerance by suppressing CAFs. Methods The interaction between mouse myofibroblast cell line LmcMF and mouse GC cell line YTN16 on M2 macrophage migration was investigated, and the inhibitory effect of Tranilast was examined in vitro. Using C57BL/6J mouse PM model established using YTN16 with co-inoculation of LmcMF, TME of resected PM treated with or without Tranilast was analyzed by immunohistochemistry. Results The addition of YTN16 cell-conditioned medium to LmcMF cells enhanced CXCL12 expression and stimulated M2 macrophage migration, whereas Tranilast inhibited the migration ability of M2 macrophages by suppressing CXCL12 secretion from LmcMF. In PM model, Tranilast inhibited tumor growth and fibrosis, M2 macrophage, and mast cell infiltration and significantly promoted CD8 + lymphocyte infiltration into the tumor, leading to apoptosis of cancer cells by an immune response. Conclusion Tranilast improved the immunosuppressive microenvironment by inhibiting CAF function in a mouse PM model. Tranilast is thus a promising candidate for the treatment of PM.

Hypoxia-Induced CD36 Expression in Gastric Cancer Cells Promotes Peritoneal Metastasis via Fatty Acid Uptake

“…Immunofluorescence was performed as described in a previous study. 18 Briefly, slides with the samples were incubated with CD36 antibody (NB400-144, rabbit, diluted 1:300, Novus Biologicals, Littleton, CO, USA) overnight at 4 °C. Immunoreactivity was visualized using anti-rabbit immunoglobulin (Ig) G secondary antibody conjugated with Alexa Fluor ® 546 (1:400; Molecular Probes/Invitrogen, Eugene, OR, USA).…”

“…Western blotting was performed according to a previously reported standard protocol. 18 The CD36 SR-B3 antibody (NB400-144, rabbit polyclonal IgG, diluted…”

“…Immunohistochemical (IHC) staining was performed according to a previously reported standard protocol. 18 CD36 antibody (NB400-144, rabbit, diluted 1:300; Novus Biologicals) and CAIX antibody (NB100-417, rabbit, diluted 1:500; Novus Biologicals) were used for the IHC assessment. Based on intensity, the staining was graded/ scored as no staining (0), weak staining (1), moderate staining (2), and strong staining (3).…”

Cancer-Associated Fibroblasts: Master Tumor Microenvironment Modifiers

“…In mouse models of peritoneal tumors, CXCL12 from CAFs was suppressed. This reduced mast cell migration and degranulation and reduced tumor fibrosis [ 104 ]. Natural killer (NK) cells, an important immune component responsible for eliminating tumor cells, interact with CAFs as tumors progress.…”

Tumor microenvironment-mediated immune tolerance in development and treatment of gastric cancer

“…Studies have shown that the antiallergic drug Tranilast can inhibit the secretory function of fibroblasts in peritoneal metastatic GC tissue, effectively improve the tumor microenvironment, increase the infiltration of CD8 + T cells, as well as reduce the infiltration of M2 macrophages and mast cells. This leads to reduced proliferation and fibrosis of GC cells ( 141 ). Futibatinib is a novel FGFR1-4 inhibitor that exhibits broad-spectrum antitumor effects in various tumors, including gastric cancer ( 142 ).…”