A Selective β-Catenin-Metadherin/CEACAM1-CCL3 Axis Mediates Metastatic Heterogeneity upon Tumor-Macrophage Interaction

Tumor heterogeneity plays a key role in cancer relapse and metastasis, however, the distinct cellular behaviors and kinetics of interactions among different cancer cell subclones and the tumor microenvironment are poorly understood. By profiling an isogenic model that resembles spontaneous human ovarian cancer metastasis with an highly metastatic (HM) and non-metastatic (NM) tumor cell pair, one finds an upregulation of Wnt/beta-catenin signaling uniquely in HM. Using humanized immunocompetent mice, one shows for the first time that activated beta-catenin acts nonautonomously to modulate the immune microenvironment by enhancing infiltrating tumor-associated macrophages (TAM) at the metastatic site. Single-cell time-lapse microscopy further reveals that upon contact with macrophages, a significant subset of HM, but not NM, becomes polyploid, a phenotype pivotal for tumor aggressiveness and therapy resistance. Moreover, HM, but not NM, polarizes macrophages to a TAM phenotype. Mechanistically, beta-catenin upregulates cancer cell surface metadherin, which communicates through CEACAM1 expressed on macrophages to produce CCL3. Tumor xenografts in humanized mice and clinical patient samples both corroborate the relevance of enhanced metastasis, TAM activation, and polyploidy in vivo. The results thus suggest that targeting the beta-catenin-metadherin/CEACAM1-CCL3 positive feedback cascade holds great therapeutic potential to disrupt polyploidization of the cancer subclones that drive metastasis.

Automated summary

Tumor heterogeneity is crucial for cancer relapse and metastasis. This study reveals the upregulation of Wnt/β-catenin signaling in highly metastatic tumors and the nonautonomous effect of activated β-catenin on the immune microenvironment by modulating tumor-associated macrophages. Additionally, it is shown that contact with macrophages induces polyploidy in a subset of highly metastatic cells, while beta-catenin polarizes macrophages to a TAM phenotype. Targeting the positive feedback cascade of metadherin/CEACAM1-CCL3 holds great therapeutic potential to disrupt polyploidization of metastatic cancer subclones.