Inflammation awakens dormant cancer cells by modulating epithelial-mesenchymal phenotypic state [Sum159]

The awakening of dormant disseminated cancer cells is responsible for the clinical relapses of patients whose primary tumors have been cured months and even years earlier. In the present study, we demonstrate that dormant breast cancer cells lodged in the lungs reside in a highly mesenchymal, non-proliferative phenotypic state. The awakening of these cells does not occur because of a cancer cell-autonomous process. Instead, inflammation and wound-healing of the surrounding tissue microenvironment causes them to shift from a highly mesenchymal to a quasi-mesenchymal phenotypic state in which they acquire stemness and proliferative ability. Once awakened, these cells can stably reside in this quasi-mesenchymal state and maintain their stemness, doing so without ongoing heterotypic signaling from the lung microenvironment. EGFR ligands released by the cells of the injured tissue microenvironment, including notably M2 type macrophages, promote dormant cancer cells to move toward this quasi-mesenchymal state, a transition that is essential for the awakening process. An understanding of the mechanisms of metastatic awakening may lead in the future to treatment strategies designed to prevent such awakening and resulting metastatic relapse. Overall design: For the samples of Sum159 ITGB4 low clone 1 beomycin treated, cells were injected into the mouse lungs through tail vein. At the end point of the experiment, lungs were harvested and dissociated into cell suspension. Cell suspension containing tumor cells were cultured in petri dishes overnight, and in the next day tdtomato+ tumor cells were sorted by FACS. RNA samples were extracted from the sorted tdtomato+ tumor cells and sent for sequencing. For the samples of Sum159 ITGB4 high, Sum159 ITGB4 low clone 1 control, cells were cultured in petri dishes. RNA samples were extracted from these cells and sent for sequencing.