Paraneoplastic renal dysfunction in fly cancer models driven by inflammatory activation of stem cells

Abstract

Tumors can induce systemic disturbances in distant organs, leading to physiological changes that enhance host morbidity. In Drosophila cancer models, tumors have been known for decades to cause hypervolemic bloating of the abdominal cavity. Here we use allograft and transgenic tumors to show that hosts display fluid retention associated with autonomously defective secretory capacity of fly renal tubules, which function analogous to those of the human kidney. Excretion from these organs is blocked by abnormal cells that originate from inappropriate activation of normally quiescent renal stem cells (RSCs). Blockage is initiated by IL-6-like oncokines that perturb renal water-transporting cells, and trigger a damage response in RSCs that proceeds pathologically. Thus, a chronic inflammatory state produced by the tumor causes paraneoplastic fluid dysregulation by altering cellular homeostasis of host renal units. Significance StatementTumors cause pathophysiological changes to host tissues, including distant organs. Here we use fruit fly cancer models to uncover mechanisms underlying paraneoplastic renal dysfunction. IL-6-like signaling from the tumor induces inflammatory signaling in renal tubule cells. Defects in these cells are sensed by normally quiescent renal stem cells, leading to inappropriate proliferation in a damage-like response. Chronic activation in the tumor context results in physical obstruction of tubule ducts and thus failures in fluid clearance. This fly work can prompt investigation of analogous mechanisms underlying renal dysfunction in cancer patients.