Trop-2 induces ADAM10-mediated cleavage of E-cadherin and drives EMT-less metastasis in colon cancer

We recently reported that activation of Trop-2 through its cleavage at R87-T88 by ADAMIO underlies Trop-2-driven progression of colon cancer. However, the mechanism of action and pathological impact of Trop-2 in metastatic diffusion remain unexplored. Through searches for molecular determinants of cancer metastasis, we identified TROP2 as unique in its up-regulation across independent colon cancer metastasis models. Overexpression of wild-type Trop-2 in KM12SM human colon cancer cells increased liver metastasis rates in vivo in immunosuppressed mice. Metastatic growth was further enhanced by a tail-less, activated Delta cytoTrop-2 mutant, indicating the Trop-2 tail as a pivotal inhibitory signaling element. In primary tumors and metastases, transcriptome analysis showed no down-regulation of CDH1 by transcription factors for epithelial-to-mesenchymal transition, thus suggesting that the pro-metastatic activity of Trop-2 is through alternative mechanisms. Trop-2 can tightly interact with ADAM10. Here, Trop-2 bound E-cadherin and stimulated ADAM10-mediated proteolytic cleavage of E-cadherin intracellular domain. This induced detachment of E-cadherin from beta-actin, and loss of cell-cell adhesion, acquisition of invasive capability, and membrane-driven activation of beta-catenin signaling, which were further enhanced by the Delta cytoTrop-2 mutant. This Trop-2/E-cadherin/beta-catenin program led to anti-apoptotic signaling, increased cell migration, and enhanced cancer-cell survival. In patients with colon cancer, activation of this Trop-2-centered program led to significantly reduced relapse-free and overall survival, indicating a major impact on progression to metastatic disease. Recently, the anti-Trop-2 mAb Sacituzumab govitecan-hziy was shown to be active against metastatic breast cancer. Our findings define the key relevance of Trop-2 as a target in metastatic colon cancer. Funding Agencies|grants of Fondazione of the Cassa di Risparmio della Provincia di Chieti; Compagnia di San PaoloCompagnia di San Paolo [2489IT]; Italian Ministry of Development [MI01_00424]; Region Abruzzo (POR FESR) [C78C14000100005]; Oncoxx Biotech (Italian Ministry of University and Research, Smart Cities and Communities) [SCN_00558]; Programma Per Giovani Ricercatori "Rita Levi Montalcini", Italian Ministry of University and Research [PGR12I7N1Z]