Non-enzymatic heparanase enhances gastric tumor proliferation via TFEB-dependent autophagy

Heparanase (HPA) is the predominant enzyme that cleaves heparan sulfate and plays a critical role in a variety of pathophysiological processes. HPA activity has been traditionally correlated with tumor metastasis due to participation in the cleavage and remodeling of the extracellular matrix (ECM). Apart from its well-characterized catalytic properties, HPA was noticed to exert biological functions not rely on its enzymatic activity. This feature is supported by studies showing induction of signaling events, such as Src and AKT, by nonenzymatic HPA mutant. We provide evidence here that active HPA and inactive HPA mutant proteins enhance gastric cancer cell growth, possibly attributed to TFEB-mediated autophagy. Similarly, HPA gene silencing resulted in decreased gastric cancer cell proliferation and autophagy. Besides, TFEB inhibition reduced cell growth and autophagy induced by nonenzymatic HPA. Notably, HPA and TFEB were significantly elevated in gastric carcinomas compared with the adjacent gastric tissue. Moreover, the elevation of HPA gene expression and upregulation of TFEB levels have been associated with advanced clinical stage and poor prognosis of gastric cancer, providing strong clinical support for a connection between TFEB and HPA. Thus, neutralizing the nonenzymatic function of HPA and the related TFEB-driven autophagy may profoundly impact gastric cancer progression.