Abstract

Lysosomes play vital roles in cellular homeostasis. In cancer cells the lysosome function is often maladaptively upregulated in order to respond to the high energy demand associated with their enhanced metabolism. Transient Receptor Potential-Mucolipin 1 (TRPML1) is a cation-selective channel mostly located at the lysosomal membrane. It promotes lysosomal/autophagic gene expression through TFEB nuclear translocation[1]. The channel plays a key role in the cell autophagic pathway and in the overall bioenergetic output by increasing the oxygen consumption in the mitochondria. TRPML1 is overexpressed in triple-negative breast cancer[2] (TNBC) and melanomas[3] and its inhibition or reduced expression decreases the in vitro proliferation and migration as well as the in vivo tumor growth. For these reasons, TRPML1 antagonists could represent an interesting treatment for specific solid tumors. An HTS campaign was performed in Axxam by screening over 300000 lead-like compounds using a cell-based FLIPR assay as primary screening tool. Among the several primary hits confirmed and qualified, 6 of them, active in the micromolar range, were chosen as starting point for the subsequent hit-to-lead activities. The effectiveness of the 6 identified hits was also confirmed using the LysoPatch assay, which allows the study of the channel directly in the lysosome membrane by employing the endogenous agonist PI_(3,5)P₂. For further characterization, compounds are going to be tested on phenotypic assays, including TFEB translocation and autophagy, and on mTRPML1 to verify cross-species activity and hTRPML3 for a preliminary selectivity assessment, in order to identify a promising lead.