A Different Trend of Heat Shock Proteins 90 mRNA and Protein Inhepatocellular Carcinoma Cell Line-Secreted Extracellular Vesicles

Abstract

Primary Hepatocellular Carcinoma (HCC) does not usually show any symptoms at the early stage and the use of biomarkers is necessary to aid in diagnosis. Recently Extracellular Vesicles (EVs), submicron membranebound structures secreted from different cell types containing a wide variety of bioactive molecules, have increased the attention in many cancers, including HCC, becoming an auspicious candidate as biomarkers and therapy in the scenario of limited diagnostic and treatment option. Many indications have shown that heat shock proteins (Hsps) are important modulators in treatment resistance and invasion of HCC becoming attractive therapeutic targets. In particular, Hsp90a/β isoforms have been found to play critical roles in regulating the proliferation, apoptosis, and metastasis of tumor cells, suggesting for these proteins a role as targets for modern anticancer therapies. The study aimedto verify the presence of Hsp90a/β in EVs secreted by an HCC tumor cell line (HepG2) and by a non-tumorigenic hepatocyte cell line (WRL68), both at protein and mRNA levels, and to analyze their expression variations. The result showed that Hsp90s are transported by the EVs as protein but not at the mRNA level. To build new therapeutic targets using EVs or other organelles as performed on exosomes in recent studies, it is essential to evaluate the action at the pre or post-transcriptional level given their different behavior in transporting proteins or mRNA.