A89: P450 1A subfamily as component of exosomes derived from HepG2 cells

Abstract

Exosomes are small vesicles formed in vesicular bodies in the endosomal network many different types of cells. Exosomes are abundantly released by tumor cells. Current knowledge of exosomes suggests that they can play an important role in the development and progression of cancer through modulation of intercellular communication within the tumour microenvironment by the transfer of protein, lipid, and RNA cargo. Hepatocellular carcinoma is the most common primary malignancy of the liver. HepG2 represents a pure cell line of human liver carcinoma. The purpose of the current study was characterization of exosomes derived from HepG2 cells line. Exosomes were isolated from HepG2 cell culture supernatant by a series of subsequent centrifugation steps. Morphology of exosomes was determined by electron microscopy. To characterize HepG2 cell derived exosomes we also examined the presence of the ER-residing protein Calnexin by Western blot. Data showed that Calnexin was absent in exosomes. Taken together, these results indicate that vesicles obtained from cell-free supernatants of HepG2 cells exhibit properties of exosomes. Proteome analysis was performed for proteins commonly expressed in HepG2 cells such as cytochromes P450 that serve important roles in the cellular detoxification process and drug metabolism. We identified members of protein families cytochromes P450 CYP1A1 и CYP1A2 in both HepG2 cells and exosomes. Thus, hepatocyte-derived exosome population should be useful in our further understanding of the hepatic function and in the identification of components that may serve as biomarkers for hepatic alterations. These tumor-derived extracellular vesicles represent a mediator of the tumor microenvironment, and their presence in the peripheral circulation may serve as a surrogate for tumor biopsies, enabling real-time diagnosis and disease monitoring.