Identifying endo-lysosomal alterations downstream of RAS mutations

Abstract

The endo-lysosomal system is primarily responsible for vesicle transport and degradation but also plays a crucial role in nutrient sensing and metabolic signaling. As a result, the state of endo-lysosomal pathways significantly influence cancer development and progression. For instance, in RAS-mutated cancers, like colorectal and pancreatic cancers, it has been shown that both lysosomal and autophagic activity has increased. However, research on the direct effects of individual oncogene mutations, such as those in RAS, remains limited. In this study, we use an inducible RPE1 model to express the mutated HRAS G12V and examine its impact on the endo-lysosomal system. Surprisingly, our findings reveal decreased endo-lysosomal protein expression, fewer endosomes and lysosomes, and a more perinuclear positioning with reduced acidification. All these observations are the opposite of previous research conducted on model cancer cell lines. Notably, TFE3 localization shifts toward the nucleus, while TFEB appears to be increasingly retained at the lysosomal surface, hinting at greater functional divergence between the lysosomal transcription factors than previously recognized. Additionally, autophagy levels show a slight increase, although further validation is required. Nevertheless, our results suggest that single oncogene mutations may exert distinct effects on the endo-lysosomal system compared to the combinatorial mutations previously observed in cancer cell lines.