Isowalsuranolide targets TrxR1/2 and triggers lysosomal biogenesis and autophagy via the p53-TFEB/TFE3 axis.

Abstract

The lysosome is transformed from a major degradative site to a dynamic regulator of cellular homeostasis. Cancer cells with altered redox environments could be exploited as potential targets for cancer therapy. The thioredoxin (Trx) system, which includes thioredoxin reductases (TrxRs), is a promising target for cancer drug development. Here, by identifying the natural product isowalsuranolide (Hdy-7), we showed that lysosomal biogenesis and autophagy are elicited by Hdy-7 via the inhibition of TrxRs. The attenuation of cellular TrxR activity led to the accumulation of ROS, which are indispensable for p53 activation and subsequent lysosomal biogenesis mediated by the transcription factor TFEB/TFE3. Knockdown of TrxR1/2 led to activation of TFEB/TFE3, thereafter increasing lysosomal biogenesis. Treatment with the ROS scavenger NAC or knockdown of p53 or SESN2 led to attenuation of the nuclear translocation of TFEB/TFE3, lysosomal biogenesis, and autophagic flux, suggesting that the TrxR1/2-p53-TFEB/TFE3 axis plays a role in maintaining lysosomal homeostasis under stress conditions other than starvation. Surprisingly, pharmacological inhibition or genetic ablation of autophagy prevented Hdy-7-induced cell death, suggesting that Hdy-7-induced autophagy is detrimental to cancer cells. Our study revealed that Hdy-7 induces ROS-mediated lysosomal biogenesis and retards cell growth by targeting TrxR1/2. This study highlights the lysosome as a regulatory hub for cellular homeostasis and as an attractive therapeutic target for a variety of lysosome-related diseases, including cancer.