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Hepatocellular carcinoma (HCC) generally occurs in the presence of chronic liver injury, often as a sequela of liver fibrosis. Hepatic progenitor cells (HPCs) are known to be capable of forming both hepatocytes and cholangiocytes in chronic liver injury, which are also considered a source of myofibroblasts and tumor-initiating cells, under carcinogenic circumstances. However, the underlying mechanisms that activate HPCs to give rise to HCC are still unclear. In current study, the correlation between HPCs activation and liver fibrosis and carcinogenesis was investigated in rats and human specimens. We analyzed the role of HPCs in tumorigenesis, by transplanting exogenous HPCs in a diethylnitrosamine-induced rat HCC model. Our data indicated that HPC activation correlated with hepatic fibrosis and hepatocarcinogenesis. We further found that exogenous HPC infusion promoted liver fibrosis and hepatocarcinogenesis, while lipopolysaccharides (LPS) played an important role in this process. However, results of our study indicated that LPS did not induce HPCs to form tumor in nude mice directly. Rather, LPS induced myofibroblast-like morphology in HPCs, which enhanced the tumorigenic potential of HPCs. Further experiments showed that LPS/Toll-like receptor 4 (TLR4) signaling mediated the differentiation of HPCs into myofibroblasts and enhanced the production of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), which led to the aberrant expression of Ras and p53 signaling pathways in HPCs, and finally, promoted the proliferation and malignant transformation of HPCs, by long non-coding RNA regulation. Besides, examination of HCC clinical samples demonstrated that IL-6 and TNF-α production correlated with HPC activation, hepatic fibrosis, and HCC recurrence. Our study indicates that both myofibroblasts and tumor cells are derived from HPCs. HPC-derived myofibroblasts create tumor microenvironment and contribute to the proliferation and malignant transformation of HPCs. Furthermore, LPS present in the chronic liver inflammation microenvironment might play an important role in hepatocarcinogenesis, by regulating the plastic potential of HPCs.

STING (also known as MITA) is critical for host defence against viruses and the activity of STING is regulated by ubiquitination. However, the deubiquitination of STING is not fully understood. Here, we show that ubiquitin-specific protease 13 (USP13) is a STING-interacting protein that catalyses deubiquitination of STING. Knockdown or knockout of USP13 potentiates activation of IRF3 and NF-κB and expression of downstream genes after HSV-1 infection or transfection of DNA ligands. USP13 deficiency results in impaired replication of HSV-1. Consistently, USP13 deficient mice are more resistant than wild-type littermates to lethal HSV-1 infection. Mechanistically, USP13 deconjugates polyubiquitin chains from STING and prevents the recruitment of TBK1 to the signalling complex, thereby negatively regulating cellular antiviral responses. Our study thus uncovers a function of USP13 in innate antiviral immunity and provides insight into the regulation of innate immunity., The cGAS-STING pathway is a DNA sensing mechanism that enables response to viral infection by inducing type 1 interferon expression. Here the authors show a mechanism by which the deubiquitinating enzyme USP13 prevents STING from enabling response to virus.

Hepatocyte nuclear factor-1beta (HNF1β) was initially identified as a liver-specific transcription factor. It is a homeobox transcription factor that functions as a homodimer or heterodimer with HNF1α. HNF1β plays an important role in organogenesis during embryonic stage, especially of the liver, kidney, and pancreas. Mutations in the HNF1β gene cause maturity-onset diabetes of the young type 5 (MODY5), renal cysts, genital malformations, and pancreas atrophy. Recently, it has been shown that the expression of HNF1β is associated with cancer risk in several tumors, including hepatocellular carcinoma, pancreatic carcinoma, renal cancer, ovarian cancer, endometrial cancer, and prostate cancer. HNF1β also regulates the expression of genes associated with stem/progenitor cells, which indicates that HNF1β may play an important role in stem cell regulation. In this review, we discuss some of the current developments about HNF1β and tumor, the relationship between HNF1β and stem/progenitor cells, and the potential pathogenesis of HNF1β in various tumors.

Hepatitis B virus (HBV) infection is a risk factor for hepatocarcinogenesis and recurrence. Here, we sought to characterize intratumoral and peritumoral expression of HBsAg and its specific receptors in HBsAg-positive hepatocellular carcinoma (HCC) patients and further examined their correlation with the recurrence-free survival (RFS). HCC tissue and adjacent normal tissue specimens were acquired from HBsAg-positive patients. The presence of HBsAg and receptors, as well as hepatic progenitor cells (HPCs) were detected by tissue microassay and immunohistochemistry. Necroinflammatory activity was evaluated by HE staining. The mean IOD of HBsAg and HBV DNA in the intratumoral tissues was markedly lower than that in the peritumoral tissues (P < 0.001). Pearson correlation analysis further showed a significant correlation between the expression of HBsAg and NTCP (r = 0.461, P < 0.001) or ASGPR (r = 0.506, P < 0.001) in peritumoral tissues. And the peritumoral HBsAg and receptors presented a positive association with necroinflammatory activity (P < 0.05). Inflammation induced by HBV infection presented a positive association with HPCs activation (P < 0.05). Additionally, due to lack of HBV receptors, HPCs was not preferentially infected with HBV, but activated HPCs had a significant correlation with HBsAg expression in peritumoral tissues, and the peritumoral HPCs activation was associated with RFS of HCC patients, therefore, the overexpression of HBsAg and receptors in peritumor were also with higher recurrence risk (P < 0.05). In conclusion, lack of HBV receptors resulted in scant HBV infection in tumor cells, and overexpression of HBsAg and receptors in peritumor was strongly associated with higher recurrence risk in HCC patients.

Hyperimmunoglobulinemia is frequently observed in patients with chronic liver diseases. However, the exact mechanism underlying the high level of antibody formation is not fully understood. In our study, we provide evidence for the functional role of the liver and the stimulation of plasma cell proliferation in hyperimmunoglobulinemia. We collected sera from patients with chronic liver diseases, and the level of serum immunoglobulins in patients was examined; this was also investigated in animal models of liver cirrhosis and hepatocellular carcinoma. An end-to-side microsurgical portacaval shunt was used to mimic liver dysfunction in rats. We used portal vein serum and inferior vena cava serum to immunize healthy rats and mice in order to confirm the function of the healthy liver in disposing of antigens and endotoxins from the gut. For the analysis of the state of plasma cell activation, plasma cells from mice were stained with PE-conjugated anti-CD138 and FITC-conjugated anti-BrdU for flow cytometry analysis. Hyperimmunoglobulinemia was observed both in patients with chronic liver diseases and in related animal models, and high plasma LPS levels were also observed. There was a significant increase in the activation and proliferation of plasma cell in mice immunized with antigens or LPS-positive serum compared with controls that were immunized with antigens and LPS-negative serum. We confirmed that the healthy liver plays an important role in disposing of antigens and endotoxins derived from the gut. Hyperimmunoglobulinemia in chronic liver diseases mainly arises due to the collateral circulation secondary to portal hypertension, gut antigens and endotoxins that bypass the liver and reach the antibody-producing cells.