Oncologic trogocytosis with Hospicells induces the expression of N-cadherin by breast cancer cells

In breast cancers, the appearance of metastasis is synonymous with poor prognosis. The metastatic process is usually associated with epithelial-mesenchymal transition (EMT) which is often induced by several soluble factors produced either by the tumour cells themselves or by cells constituting the tumour microenvironment. The aim of the present study was to determine whether the mesenchymal properties given by some molecules such as N-cadherin, for instance, could be acquired by cancer cells via the trogocytosis process with cells of the tumour microenvironment. Hospicells are stromal cells which were first isolated from cancer cell aggregates of patients with ovarian cancer. We recently showed that these cells are immunosuppressive for T lymphocyte functions and confer chemoresistance to cancer cells by the transfer of the MDR protein via trogocytosis. In this study, we showed that a mammary cancer cell line (MDA-MB-231) acquires patches of membrane via oncologic trogocytosis with Hospicells. This unidirectional and active process depends on actin polymerization and can be increased via inhibition of the Src family and decreased via inhibition of PI3K. Trogocytosis between Hospicells and MDA-MB-231 does not lead to the direct acquisition of N-cadherin but rather it leads to the production of soluble factor(s) which induce de novo expression of N-cadherin by the cancer cells. The novelty here is that this factor is produced only if cancer cells interact and undergo trogocytosis with Hospicells. This new expression could confer a more invasive phenotype to the cancer cells and thus can explain the correlation of the presence of Hospicells with the number of invaded lymph nodes in patients with mammary adenocarcinoma.