CAP2 promotes gastric cancer metastasis by mediating the interaction between tumor cells and tumor-associated macrophages
Guohao Zhang, … , Ruinan Zhao, Peng Gao
Guohao Zhang, … , Ruinan Zhao, Peng Gao
Published September 14, 2023
Citation Information: J Clin Invest. 2023;133(21):e166224. https://doi.org/10.1172/JCI166224.
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Research Article Gastroenterology Oncology

CAP2 promotes gastric cancer metastasis by mediating the interaction between tumor cells and tumor-associated macrophages

Abstract

The metastasis of cancer cells is the main cause of death in patients with gastric cancer (GC). Mounting evidence has demonstrated the vital importance of tumor-associated macrophages in promoting tumor invasion and metastasis; however, the interaction between tumor cells and macrophages in GC is largely unknown. In this study, we demonstrated that cyclase-associated protein 2 (CAP2) was upregulated in GC, especially in cases with lymph node metastasis, and was correlated with a poorer prognosis. The transcription factor JUN directly bound to the promoter region of CAP2 and activated CAP2 transcription. The N-terminal domain of CAP2 bound to the WD5 to WD7 domains of receptor for activated C kinase 1 (RACK1) and induced M2 macrophage polarization by activating the SRC/focal adhesion kinase (FAK)/ERK signaling pathway, which resulted in IL-4 and IL-10 secretion. Polarized M2 macrophages induced premetastatic niche formation and promoted GC metastasis by secreting TGFB1, which created a TGFB1/JUN/CAP2 positive-feedback loop to activate CAP2 expression continuously. Furthermore, we identified salvianolic acid B as an inhibitor of CAP2, which effectively inhibited GC cell invasion capabilities by suppressing the SRC/FAK/ERK signaling pathway. Our data suggest that CAP2, a key molecule mediating the interaction between GC cells and tumor-associated macrophages, may be a promising therapeutic target for suppressing tumor metastasis in GC.

Authors

Guohao Zhang, Zhaoxin Gao, Xiangyu Guo, Ranran Ma, Xiaojie Wang, Pan Zhou, Chunlan Li, Zhiyuan Tang, Ruinan Zhao, Peng Gao

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Figure 5

CAP2 competitively binds to domains WD5–WD7 of RACK1 and dissociates SRC.

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CAP2 competitively binds to domains WD5–WD7 of RACK1 and dissociates SRC...
(A) Schematic representation of the RACK1 domains. (B) HA-tagged WT-RACK1, WD6-1, WD5-1, WD4-1, WD3-1, WD2-1, and WD1 were individually overexpressed in MKN45 cells, and anti-HA–tagged antibodies were used for co-IP. (C) HA-tagged WT-RACK1, WD2-7, WD3-7, WD4-7, WD5-7, WD6-7, and WD7 were individually overexpressed in MKN45 cells, and anti-HA–tagged antibodies were used for co-IP. (D) Schematic diagram of CAP2 protein truncation. (E) Overexpression of His-tagged WT-CAP2, CAP2(1–210bp), CAP2(1–310bp), CAP2(211–477bp), and CAP2(311–477bp) in MKN45 cells, immunoprecipitated with an anti-His-tag antibody. (F and G) Immunoprecipitation was performed using an IP-grade anti-RACK1 antibody. The level of SRC binding to RACK1 in GC cells with or without CAP2 expression was detected by Western blotting. (H) The expression and phosphorylation levels of the SRC/FAK/ERK signaling pathway in GC cells with or without CAP2 knockdown were detected by Western blotting. (I) Western blotting was conducted to determine the expression and phosphorylation levels of SRC/FAK/ERK/IL-4 and IL-10 in xenografted tumors. (J) SRC inhibitor (PP2) was added to GC cells overexpressing CAP2, and the expression and phosphorylation levels of SRC/FAK/ERK/IL-4 and IL-10 were detected by Western blotting.