43P Looking for Therapeutic Targets on the Proteome Profile of Endometrial Cancer Stem Cells

Endometrial cancer (EC) is one of the most frequent gynaecological malignant diseases whose incidence presents an increasing trend. Cancer stem cells (CSC), a subpopulation of undifferentiated tumour cells identified in EC, are the main actors in the resistance mechanisms to conventional therapies. Thus, the main aim of this study is to identify novel molecular targets in endometrial CSC for the future development of innovative targeted therapies for EC. Two EC cell lines, ECC-1 and RL95-2, were cultured, and endometrial CSC were obtained through an optimized 5-day sphere formation assay. A proteomic profile of cell lines and endometrial CSC was determined through mass spectrometry-based proteomics. The analysis was performed through the comparison of CSC vs. cell line proteins significantly up-regulated by a 40-fold change and their cellular localization. R package was used for statistical analysis. The proteomic analysis of ECC-1 samples allowed the identification of 477 up-regulated ECC-1-CSC-specific proteins, 108 ECC-1-specific proteins, and 2306 common proteins. Regarding RL95-2 samples, the analysis identified 76 up-regulated RL95-2-CSC-specific, 994 cell line-specific, and 1420 common proteins. The cellular localization of up-regulated proteins identified from CSC populations was mainly the cytoplasm (25-31%), nucleus (19-23%), and membrane (21-22%). Regarding the functional analysis, the more regulated subcategories were the intracellular ferritin complex, poly(A) RNA binding, (acetyl-CoA carboxylase) kinase activity, (hydroxymethylglutaryl-CoA reductase (NADPH)) kinase activity, and ubiquitinyl hydrolase activity for ECC-1-CSC vs. ECC-1; the proteasome, cytosol, extracellular vesicular exosome, poly(A) RNA binding, glutamate dehydrogenase (NAD+) activity, and glutamate dehydrogenase (NADP+) activity for RL95-2-CSC vs. RL95-2; and poly(A) RNA binding, (acetyl-CoA carboxylase) kinase activity, NADPH kinase activity, and ubiquitinyl hydrolase activity for both. CSC population-specific proteins were identified, as well as their cellular localization and functional enrichment. This information allows for the future development of endometrial CSC targeted therapies.