The Role of Extracellular Vesicles as Shuttles of RNA and Their Clinical Significance as Biomarkers in Hepatocellular Carcinoma

Survey of organ-derived small extracellular vesicles and particles (sEVPs) to identify selective protein markers in mouse serum

Extracellular vesicles and particles (EVPs) are secreted by organs across the body into different circulatory systems, including the bloodstream, and reflect pathophysiologic conditions of the organ. However, the heterogeneity of EVPs in the blood makes it challenging to determine their organ of origin. We hypothesized that small (s)EVPs (<100 nm in diameter) in the bloodstream carry distinctive protein signatures associated with each originating organ, and we investigated this possibility by studying the proteomes of sEVPs produced by six major organs (brain, liver, lung, heart, kidney, fat). We found that each organ contained distinctive sEVP proteins: 68 proteins were preferentially found in brain sEVPs, 194 in liver, 39 in lung, 15 in heart, 29 in kidney, and 33 in fat. Furthermore, we isolated sEVPs from blood and validated the presence of sEVP proteins associated with the brain (DPP6, SYT1, DNM1L), liver (FABPL, ARG1, ASGR1/2), lung (SFPTA1), heart (CPT1B), kidney (SLC31), and fat (GDN). We further discovered altered levels of these proteins in serum sEVPs prepared from old mice compared to young mice. In sum, we have cataloged sEVP proteins that can serve as potential biomarkers for organ identification in serum and show differential expression with age.

Extracellular vesicle RNA signaling in the liver tumor microenvironment

The tumor microenvironment (TME) in liver cancers such as hepatocellular cancer (HCC) consists of a complex milieu of liver tissue-resident cells, infiltrated immune cells, and secreted factors that collectively serve to promote tumor growth and progression. Intercellular crosstalk contributes to tissue homeostasis, and perturbations during injury, inflammation and tumorigenesis that are important for tumor progression. Extracellular vesicle (EV)-mediated transfer of a payload of RNA molecules that serve as an intercellular signaling is an important contributor to tissue homeostasis within the TME. Several types of RNA have been implicated in EV-mediated signaling. Biological processes that can be modulated by EV RNA signaling within the liver include tumor growth, invasion, metastasis, angiogenesis, and modulation of the immune cell activities. This mini-review describes the liver TME, and the biological effects of EV RNA-mediated signaling within the liver to highlight the role of EV RNA in intercellular communication.

Extracellular Vesicle-Encapsulated MicroRNA-375 from Bone Marrow-Derived Mesenchymal Stem Cells Inhibits Hepatocellular Carcinoma Progression through Regulating HOXB3-Mediated Wnt/β-Catenin Pathway

Nowadays, microRNA-375 (miR-375) has been implicated in many types of cancers, including hepatocellular carcinoma (HCC), and the functions of miRNAs encapsulated by extracellular vesicles (EV) in HCC progression have also been extensively investigated. In this research, we aimed to probe into the mechanism of EV-encapsulated miR-375 from bone marrow-derived mesenchymal stem cells (BM-MSCs) in HCC progression. At first, miR-375 expression in HCC tissues and cells was detected using RT-qPCR, and miR-375 was overexpressed to specify the effects of miR-375 on the malignant phenotype of HCC cells. miR-375 was downregulated in HCC, and overexpression of miR-375 suppressed HCC cell growth. Then, BM-MSCs and EV were isolated and identified, and, EV were cocultured with HCC cells for further functional assays. It was found that miR-375 encapsulated by EV could restrict the malignant phenotypes of HCC cells. Furthermore, the downstream genes and signaling cascades involved in HCC growth were investigated. HOXB3 was determined to be a downstream target of miR-375, and upregulation of miR-375 decreased Wnt1 and β-catenin protein expression. Furthermore, HOXB3 blocked the repressive effects of miR-375 on HCC cells and Wnt1 and β-catenin expression. This study highlights that miR-375 encapsulated by EV inhibits HCC development via modulating the HOXB3/Wnt/β-catenin axis.

Critical biomarkers of hepatocellular carcinoma in body fluids and gut microbiota

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer and one of the major causes of cancer-related death. The development of specific non-invasive or diagnostic markers from blood, urine and feces may represent a valuable tool for detecting HCC at an early stage. Biomarkers are considered novel potential targets for therapeutic intervention. It helps in the prediction of prognosis or recurrence of HCC, and also assist in the selection of appropriate treatment modality. We summarize the most relevant existing data about various biomarkers that play a key role in the progression of HCC.