Precancerous liver diseases do not cause increased mutagenesis in liver stem cells

Inflammatory liver disease increases the risk of developing primary liver cancer. The mechanism through which liver disease induces tumorigenesis remains unclear, but is thought to occur via increased mutagenesis. Here, we performed whole-genome sequencing on clonally expanded single liver stem cells cultured as intrahepatic cholangiocyte organoids (ICOs) from patients with alcoholic cirrhosis, non-alcoholic steatohepatitis (NASH), and primary sclerosing cholangitis (PSC). Surprisingly, we find that these precancerous liver disease conditions do not result in a detectable increased accumulation of mutations, nor altered mutation types in individual liver stem cells. This finding contrasts with the mutational load and typical mutational signatures reported for liver tumors, and argues against the hypothesis that liver disease drives tumorigenesis via a direct mechanism of induced mutagenesis. Disease conditions in the liver may thus act through indirect mechanisms to drive the transition from healthy to cancerous cells, such as changes to the microenvironment that favor the outgrowth of precancerous cells.

LncRNA TCL6 Contributes to CSC-like Properties via Modulating TP53 in HCC

BackgroundHepatocellular carcinoma (HCC) is the most common malignant tumors, accounting for most of the adult primary liver cancer. Herein, we aimed to analyze the expression of long non-coding RNA-T cell leukemia/lymphoma 6 (lncRNA-TCL6) in HCC and elucidate its mechanism involved in the HCC progression. Methodse performed RNA extraction and quantitative real-time polymerase chain reaction assays, spheroid formation assays, flow cytometry and western blot assays to assess the effect of TCL6 on the liver CSCs marker CD133 expression rate, sphere-forming ability of liver stem cells, and the relationship between TCL6 expression and stem cell factor (TP53, P21, CD44, KLF4, OCT4, Nanog, and Sox2). In addition, we used a dual luciferase assay to verify the relationship between miR-106a-5p and TP53.ResultsKnockdown of TCL6 expression significantly improved the CD133 expression rate and the liver stem cells sphere-forming ability in HCC, while TCL6 overexpression in HCC showed the opposite effect. Knockdown of TCL6 upregulated the KLF4mRNA expression, while TCL6 overexpression in HCC inhibited the TP53 and CDKN1A expression. Western blot assays showed that TCL6 expression was positively correlated with TP53 and P21, while negatively correlated with stem cell factor. Dual luciferase assay showed that TP53 was a target of miR-106a-5p.ConclusionResults suggested that reprogramming-related TCL6 may be a novel tumor suppressor gene in HCC, which inhibits the self-renewal of liver CSCs, in part by promoting the TP53 expression.

Human Liver Stem Cells: A Liver-Derived Mesenchymal Stromal Cell-Like Population With Pro-regenerative Properties

Human liver stem cells (HLSCs) were described for the first time in 2006 as a new stem cell population derived from healthy human livers. Like mesenchymal stromal cells, HLSCs exhibit multipotent and immunomodulatory properties. HLSCs can differentiate into several lineages under defined in vitro conditions, such as mature hepatocytes, osteocytes, endothelial cells, and islet-like cell organoids. Over the years, HLSCs have been shown to contribute to tissue repair and regeneration in different in vivo models, leading to more than five granted patents and over 15 peer reviewed scientific articles elucidating their potential therapeutic role in various experimental pathologies. In addition, HLSCs have recently completed a Phase 1 study evaluating their safety post intrahepatic injection in infants with inherited neonatal onset hyperammonemia. Even though a lot of progress has been made in understanding HLSCs over the past years, some important questions regarding the mechanisms of action remain to be elucidated. Among the mechanisms of interaction of HLSCs with their environment, a paracrine interface has emerged involving extracellular vesicles (EVs) as vehicles for transferring active biological materials. In our group, the EVs derived from HLSCs have been studied in vitro as well as in vivo. Our attention has mainly been focused on understanding the in vivo ability of HLSC–derived EVs as modulators of tissue regeneration, inflammation, fibrosis, and tumor growth. This review article aims to discuss in detail the role of HLSCs and HLSC-EVs in these processes and their possible future therapeutic applications.