Salivary extracellular vesicle-associated exRNA as cancer biomarker

Extracellular vesicles (EVs) secreted in biological fluids contain several transcripts of the cell of origin, which may modify the functions and phenotype of proximal and distant cells. Cancer-derived EVs may promote a favorable microenvironment for cancer growth and invasion by acting on stroma and endothelial cells and may favor metastasis formation. The transcripts contained in cancer EVs may be exploited as biomarkers. Protein and extracellular RNA (exRNA) profiling in patient bio-fluids, such as blood and urine, was performed to identify molecular features with potential diagnostic and prognostic values. EVs are concentrated in saliva, and salivary EVs are particularly enriched in exRNAs. Several studies were focused on salivary EVs for the detection of biomarkers either of non-oral or oral cancers. The present paper provides an overview of the available studies on the diagnostic potential of exRNA profiling in salivary EVs

Human Liver Stem Cell-Derived Extracellular Vesicles Target Hepatic Stellate Cells and Attenuate Their Pro-fibrotic Phenotype

Liver fibrosis occurs in response to chronic liver injury and is characterized by an excessive deposition of extracellular matrix. Activated hepatic stellate cells are primarily responsible for this process. A possible strategy to counteract the development of hepatic fibrosis could be the reversion of the activated phenotype of hepatic stellate cells. Extracellular vesicles (EVs) are nanosized membrane vesicles involved in intercellular communication. Our previous studies have demonstrated that EVs derived from human liver stem cells (HLSCs), a multipotent population of adult stem cells of the liver with mesenchymal-like phenotype, exert in vivo anti-fibrotic activity in the liver. However, the mechanism of action of these EVs remains to be determined. We set up an in vitro model of hepatic fibrosis using a human hepatic stellate cell line (LX-2) activated by transforming growth factor-beta 1 (TGF-β1). Then, we investigated the effect of EVs obtained from HLSCs and from human bone marrow-derived mesenchymal stromal cells (MSCs) on activated LX-2. The incubation of activated LX-2 with HLSC-EVs reduced the expression level of alpha-smooth muscle actin (α-SMA). Conversely, MSC-derived EVs induced an increase in the expression of pro-fibrotic markers in activated LX-2. The analysis of the RNA cargo of HLSC-EVs revealed the presence of several miRNAs involved in the regulation of fibrosis and inflammation. Predictive target analysis indicated that several microRNAs (miRNAs) contained into HLSC-EVs could possibly target pro-fibrotic transcripts. In particular, we demonstrated that HLSC-EVs shuttled miR-146a-5p and that treatment with HLSC-EVs increased miR-146a-5p expression in LX-2. In conclusion, this study demonstrates that HLSC-EVs can attenuate the activated phenotype of hepatic stellate cells and that their biological effect may be mediated by the delivery of anti-fibrotic miRNAs, such as miR-146a-5p

Role of Lefty in the anti tumor activity of human adult liver stem cells

Recent studies demonstrated that factors derived from embryonic stem cells inhibit the tumorigenicity of a variety of cancer cell lines. Embryonic stem cell-secreted Lefty, an inhibitor of Nodal-signalling pathway, was implicated in reprogramming cancer cells. Whether adult stem cells exhibited similar properties has not been explored. The aim of the present study was to investigate whether the conditioned medium (CM) derived from adult stem cells influence in vitro and in vivo tumor growth by a Nodal-dependent pathway. In particular we compared the anti-tumor effect of CM from human liver stem cells (HLSC) with that of bone marrow-derived mesenchymal stem cells (MSC). We found that HLSC-CM inhibited the in vitro growth and promoted apoptosis in HepG2 cells that expressed a deregulated Nodal pathway. The effect of HLSC-CM was related to the presence of Lefty A in the CM of HLSC. Silencing Lefty A in HLSC or Lefty A blockade with a blocking peptide abrogated the anti-proliferative and pro-apoptotic effect of HLSC-CM. Moreover, the administration of human recombinant Lefty A protein mimicked the effect of HLSC-CM indicating that Nodal pathway is critical for the growth of HepG2. At variance of HLSC, bone marrow-derived MSC did not express and release Lefty A and the MSC-CM did not exhibited an anti-tumor activity in vitro, but rather stimulated proliferation of HepG2. In addition, the intra-tumor administration of HLSC-CM was able to inhibit the in vivo growth of HepG2 hepatoma cells implanted subcutaneously in SCID mice. At variance, HLSC-CM derived from Lefty A silenced HLSC was unable to inhibit tumor growth. In conclusion, the results of present study suggest that Lefty A may account for the tumor suppressive activity of HLSC as a result of an inhibition of the Nodal-signalling pathway by a mechanism similar to that described for embryonic stem cells