Trop-2 inactivates E-cadherin and drives colon cancer metastasis.

Abstract

e15576 Background: Metastatic diffusion is the biggest hurdle for colon cancer (CRC) cure and the identification of decisive drivers of CRC metastasis is an urgent need in CRC care. Methods: The expression of target molecules in primary tumors and metastases was systematically assessed by DNA array and IHC analysis. Cell-cell adhesion capacity was quantified in 2D cell cultures and in HCT116 CRC cell spheroids. Pro-metastatic impact of wtTrop-2 and activated, tail-less Trop-2 (Δcyto) was assessed in vivo in orthotopic diffusion models of KM12SM CRC cells. Primary CRC and metastasis transcriptomes were analyzed for differential induction of EMT determinants. Kaplan–Meier plots were used to illustrate survival and metastatic relapse in independent case series of CRC patients. Results: Trop-2 was identified as uniquely upregulated in CRC models by transcriptome analysis. wtTrop-2 and ΔcytoTrop-2 were shown to induce cell migration, wound-healing and resistance to apoptosis induction . wtTrop-2 increased the metastatic capacity of KM12SM cells, raising metastasis diffusion from 45% for control cells to 90% for wtTrop-2 transfectants. The constitutively-active ΔcytoTrop-2 further boosted metastatic spreading, with metastatic livers reaching up to four times their normal size. Constitutive high expression of E-cadherin was revealed in cancer metastases. No evidence was obtained for transcriptional down-regulation of epithelial differentiation biomarkers. No induction of EMT transcription factors was observed in Trop-2-activated cells. Trop-2 tightly bound E-cadherin and caused its release from the cytoskeleton, for loss of cell-cell adhesion and activation of β-catenin. The Trop-2/E-cadherin/β-catenin-driven pro-metastatic program was recapitulated in CRC patients and was shown to impact on CRC metastatic relapse and overall patient survival. Conclusions: We identify Trop-2-driven functional inactivation of E-cadherin as a key driver of metastatic diffusion in CRC. These findings may pave the way for novel multi-marker personalized diagnostics and anti-cancer therapies. [Table: see text]