Abstract LB189: Elucidating a mechanistic link between progranulin and lysosomal function in SW13 cells: Implications for inflammation and lipid metabolism

Abstract

Abstract The SW13 human adrenocortical carcinoma line is a uniquely powerful model in which to probe the relationship between progranulin processing and cellular activity as it exists in two epigenetically distinct subtypes. The SW13- subtype has an epithelial morphology and is highly proliferative, while the SW13+ subtype has a mesenchymal-like phenotype and a higher metastatic potential. These two subtypes both express progranulin and interconvert by epigenetic mechanisms, as treatment of SW13- cells with histone deacetylase inhibitors (HDACi) adopt a SW13+ phenotype. Progranulin is composed of 7½ highly conserved granulin repeats which are subject to proteolytic processing and may serve as a prognostic biomarker in cancer as progranulin units regulate varied cellular activities including proliferation, migration, inflammation, and lysosomal function. Thus, biological activity of progranulin is dependent on the cellular proteases expressed. Indicative of differential processing, treatment of SW13- cells with exogenous progranulin results in an increase in growth rate, while no effect on SW13+ cell growth was observed. As the SW13+ subtype expresses a higher amount of progranulin than the SW13- subtype, these data are consistent with an inability of SW13+ to process endogenous progranulin to mitogenic granulin unit(s). Immunoblotting with granulin-specific antibodies indicates that progranulin may be processed differently in each subtype. In this work, we focused on lysosomes as a potential site for differential processing of progranulin for two reasons. First, lysosomal proteases have been shown to process progranulin and progranulin itself plays a role in lysosome maturation. Second, differences in lysosomal pH between the two subtypes have been detected using two pH-sensitive dyes which localize to the lysosome. Interestingly, proteomic analysis of lysosomes isolated from each subtype confirms lysosomal dysfunction and suggests upregulation of inflammatory proteins in SW13+ cells. Both proteomics and lipidomics suggest alterations in lipid metabolism. Ongoing experiments will address whether restoration of lysosomal function impacts progranulin production and/or processing in SW13 subtypes. Citation Format: Kathryn J. Leyva, Andrew Z. Yang, Pegah Biparva, Chika Okonya, Chandana K. Uppalapati, Alisha M. Harrison, Agnes S. Pascual, Elizabeth E. Hull. Elucidating a mechanistic link between progranulin and lysosomal function in SW13 cells: Implications for inflammation and lipid metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB189.