Tumor-associated macrophages drive spheroid formation during early transcoelomic metastasis of ovarian cancer
Mingzhu Yin, Xia Li, Shu Tan, Huanjiao Jenny Zhou, Weidong Ji, Stefania Bellone, Xiaocao Xu, Haifeng Zhang, Alessandro D. Santin, Ge Lou, Wang Min
Mingzhu Yin, Xia Li, Shu Tan, Huanjiao Jenny Zhou, Weidong Ji, Stefania Bellone, Xiaocao Xu, Haifeng Zhang, Alessandro D. Santin, Ge Lou, Wang Min
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Research Article Inflammation Oncology

Tumor-associated macrophages drive spheroid formation during early transcoelomic metastasis of ovarian cancer

Abstract

Tumor-associated macrophages (TAMs) can influence ovarian cancer growth, migration, and metastasis, but the detailed mechanisms underlying ovarian cancer metastasis remain unclear. Here, we have shown a strong correlation between TAM-associated spheroids and the clinical pathology of ovarian cancer. Further, we have determined that TAMs promote spheroid formation and tumor growth at early stages of transcoelomic metastasis in an established mouse model for epithelial ovarian cancer. M2 macrophage–like TAMs were localized in the center of spheroids and secreted EGF, which upregulated αMβ2 integrin on TAMs and ICAM-1 on tumor cells to promote association between tumor cells and TAM. Moreover, EGF secreted by TAMs activated EGFR on tumor cells, which in turn upregulated VEGF/VEGFR signaling in surrounding tumor cells to support tumor cell proliferation and migration. Pharmacological blockade of EGFR or antibody neutralization of ICAM-1 in TAMs blunted spheroid formation and ovarian cancer progression in mouse models. These findings suggest that EGF secreted from TAMs plays a critical role in promoting early transcoelomic metastasis of ovarian cancer. As transcoelomic metastasis is also associated with many other cancers, such as pancreatic and colon cancers, our findings uncover a mechanism for TAM-mediated spheroid formation and provide a potential target for the treatment of ovarian cancer and other transcoelomic metastatic cancers.

Authors

Mingzhu Yin, Xia Li, Shu Tan, Huanjiao Jenny Zhou, Weidong Ji, Stefania Bellone, Xiaocao Xu, Haifeng Zhang, Alessandro D. Santin, Ge Lou, Wang Min

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Figure 8

TAMs promote adhesion with EGFR+ tumor cells through integrin αMβ2 and ICAM-1 interaction.

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TAMs promote adhesion with EGFR+ tumor cells through integrin αMβ2 and I...
(A) Immunofluorescent stainings of CD68 with ICAM-1 in spheroids harvested from ascites of OC mice. Representative images of spheroids from n = 5 mice are shown. Scale bar: 10 μm. (B and C) PE-ID8 cells were treated with EGF in the absence or presence of EGFR inhibitor erlotinib or ERK inhibitor PD98059 (10 nM) for 24 hours. ICAM-1 protein was determined by Western blot. Relative levels of ICAM-1 were quantified. (D and E) ID8 cells were treated with EGF or VEGF-C in the absence or presence of MAZ51 (VEGFR3 inhibitor) for 24 hours. ICAM-1 was determined by Western blot (D). Relative protein levels of ICAM-1 were quantified (E). (F–K) Effects of ICAM-1 neutralization antibodies on spheroid formation. 3D cocultures of mouse TAM–ID8 (F–H) and human TAM-SKOV3 (I–K) were performed as in Figure 7 in the presence of anti-mouse ICAM-1 or anti-human ICAM-1, respectively. Number and size of spheroids were measured at 48 hours. Scale bars: 50 μm (F); 25 μm (I). Three independent experiments were performed. Data are presented as mean ± SEM. **P < 0.01; ***P < 0.001. (L–Q) An orthotopic mouse model was established by injecting mouse ID8 OCs i.p. into C57BL/6 female recipient mice. Mice were then either treated with IgG or anti-mouse ICAM-1 antibody by i.p. injection. Mouse body weight gain was measured at indicated time points (days 0–50) (L). Ascetic volume (M) and tumor weight (N) were measured at day 50. (O–Q) Spheroids were examined by H&E staining (O). Total number (P) and size (Q) of spheroids were quantified. Data are presented as mean ± SEM. n = 10. **P < 0.001 (2-sided Student’s t test).