Cell expression patterns of CD147 in N-diethylnitrosamine/phenobarbital-induced mouse hepatocellular carcinoma

MFGE8 protects against CCl4 -induced liver injury by reducing apoptosis and promoting proliferation of hepatocytes

Milk fat globule-EGF factor 8 (MFGE8) has been reported to play various roles in acute injury and inflammation response. However, the role of MFGE8 in liver injury is poorly investigated. The present research was designed to clarify the expression and function of MFGE8 in carbon tetrachloride (CCl₄ )-induced liver injury. Using serum cytokine arrays, we selected a promising cytokine MFGE8 as the candidate in the process of hepatitis-fibrosis-hepatocellular carcinoma (HCC) progression, based on the elevated expression in both hepatic fibrosis and HCC models. We validated the increased expression of MFGE8 in liver tissues and serum samples of acute and chronic CCl₄ -induced mice. Immunohistochemistry staining of mouse liver tissues indicated that elevated MFGE8 expression was mainly derived from the injured hepatocytes. In addition, MFGE8 expression in the supernatant of primary hepatocytes was accumulated with prolongation of culture time, and CCl₄ treatment further increased the expression of MFGE8. Moreover, a strong correlation between serum MFGE8 expression and liver transaminase activities suggested that MFGE8 may be a novel candidate in liver injury. Intriguingly, mice pretreated with MFGE8 were protected from CCl₄ -induced liver injury through antiapoptosis role in the early stage and proproliferation role in the late stage. MFGE8 reduced apoptosis by inhibiting the activation of IRE1α/ASK1/JNK pathway and promoted proliferation by phosphorylation of ERK and AKT. Moreover, serum MFGE8 expression was increased in hepatitis patients while decreased in liver cirrhosis patients. All the results suggest MFGE8 as a novel marker and promising therapeutic agent of liver injury.

Basolateral CD147 induces hepatocyte polarity loss by E-cadherin ubiquitination and degradation in hepatocellular carcinoma progress

Hepatocytes are epithelial cells with highly specialized polarity. The disorder and loss of hepatocyte polarity leads to a weakness of cell adhesion and connection, the induction of epithelial-mesenchymal transition, and eventually the occurrence of hepatocellular carcinoma (HCC). Cluster of differentiation 147 (CD147), a tumor-related glycoprotein, promotes epithelial-mesenchymal transition and the invasion of HCC. However, the function of CD147 in hepatocyte depolarization is unknown. Here we identified that CD147 was basolaterally polarized in hepatocyte membrane of liver tissues and HepG2 cells. CD147 not only promoted transforming growth factor-β1-mediated hepatocyte polarity loss but also directly induced endocytosis and down-regulation of E-cadherin which contributed to hepatocyte depolarization. Overexpression of CD147 induced Src activation and subsequently recruited ubiquitin ligase Hakai for E-cadherin ubiquitination and lysosomal degradation, leading to decreases of partitioning defective 3 expression and β-catenin nuclear translocation. This signal transduction was initiated by competitive binding of CD147 with integrin β1 that interrupted the interaction between the Arg-Gly-Asp motif of fibronectin and integrin β1. The specific antibodies targeting integrin α5 and β1 reversed the decrease of E-cadherin and partitioning defective 3 levels induced by CD147 overexpression. In human liver tissues, CD147 polarity rates significantly declined from liver cirrhosis (71.4%) to HCC (10.4%). CD147-polarized localization negatively correlated with Child-Pugh scores in human liver cirrhosis (r = -0.6092, P < 0.0001) and positively correlated with differentiation grades in HCC (r = 0.2060, P = 0.004). HCC patients with CD147-polarized localization had significantly better overall survival than patients with CD147 nonpolarity (P = 0.021).

CONCLUSION

The ectopic CD147-polarized distribution on basolateral membrane promotes hepatocyte depolarization by activation of the CD147-integrin α5β1-E-cadherin ubiquitination-partitioning defective 3 decrease and β-catenin translocation signaling cascade, replenishing a molecular pathway in hepatic carcinogenesis. (Hepatology 2018;68:317-332).

Animal models as a tool in hepatocellular carcinoma research: A Review

Cancer is the first cause of death in developed countries and the second in developing countries. Concerning the most frequent worldwide-diagnosed cancer, primary liver cancer represents approximately 4% of all new cancer cases diagnosed globally. However, among primary liver cancer, hepatocellular carcinoma is by far the most common histological subtype. Notwithstanding the health promotion and disease prevention campaigns, more than half a million new hepatocellular carcinoma cases are reported yearly, being estimated to growth continuously until 2020. Taking this scenario under consideration and the fact that some aspects concerning hepatocellular carcinoma evolution and metastasize process are still unknown, animal models assume a crucial role to understand this disease. The animal models have also provided the opportunity to screen new therapeutic strategies. The present review was supported on research and review papers aiming the complexity and often neglected chemically induced animal models in hepatocarcinogenesis research. Despite the ongoing debate, chemically induced animal models, namely, mice and rat, can provide unique valuable information on the biotransformation mechanisms against xenobiotics and apprehend the deleterious effects on DNA and cell proteins leading to carcinogenic development. In addition, taking under consideration that no model achieves all hepatocellular carcinoma research purposes, criteria to define the " ideal" animal model, depending on the researchers' approach, are also discussed in this review.

Regulation of a TGF-β1-CD147 self-sustaining network in the differentiation plasticity of hepatocellular carcinoma cells

Cellular plasticity has an important role in the progression of hepatocellular carcinoma (HCC). In this study, the involvement of a TGF-β1-CD147 self-sustaining network in the regulation of the dedifferentiation progress was fully explored in HCC cell lines, hepatocyte-specific basigin/CD147-knockout mice and human HCC tissues. We demonstrated that TGF-β1 stimulation upregulated CD147 expression and mediated the dedifferentiation of HCC cells, whereas all-trans-retinoic acid induced the downregulation of CD147 and promoted differentiation in HCC cells. Overexpression of CD147 induced the dedifferentiation and enhanced the malignancy of HCC cells, and increased the transcriptional expression of TGF-β1 by activating β-catenin. CD147-induced matrix metalloproteinase (MMP) production activated pro-TGF-β1. The activated TGF-β1 signaling subsequently repressed the HNF4α expression via Smad-Snail1 signaling and enhanced the dedifferentiation progress. Hepatocyte-specific basigin/CD147-knockout mice decreased the susceptibility to N-nitrosodiethylamine-induced tumorigenesis by suppressing TGF-β1-CD147 signaling and inhibiting dedifferentiation in hepatocytes during tumor progression. CD147 was positively correlated with TGF-β1 and negatively correlated with HNF4α in human HCC tissues. Positive CD147 staining and lower HNF4α levels in tumor tissues were significantly associated with poor survival of patients with HCC. The overexpression of HNF4α and Smad7 and the deletion of CD147 by lentiviral vectors jointly reprogrammed the expression profile of hepatocyte markers and attenuated malignant properties including proliferation, cell survival and tumor growth of HCC cells. Our results highlight the important role of the TGF-β1-CD147 self-sustaining network in driving HCC development by regulating differentiation plasticity, which provides a strong basis for further investigations of the differentiation therapy of HCC targeting TGF-β1 and CD147.

Activation of TGF-β1-CD147 positive feedback loop in hepatic stellate cells promotes liver fibrosis

Activation of hepatic stellate cells (HSCs) by transforming growth factor-β1 (TGF-β1) initiates HBV-associated fibrogenesis. The mechanism of TGF-β1 modulating HSC activation is not fully uncovered. We hypothesized a positive feedback signaling loop of TGF-β1-CD147 promoting liver fibrogenesis by activation of HSCs. Human HSC cell line LX-2 and spontaneous liver fibrosis model derived from HBV transgenic mice were used to evaluate the activation of molecules in the signaling loop. Wound healing and cell contraction assay were performed to detect the CD147-overexpressed HSC migration and contraction. The transcriptional regulation of CD147 by TGF-β1/Smad4 was determined using dual-luciferase reporter assay and chromatin immunoprecipitation. We found that a positive reciprocal regulation between TGF-β1 and CD147 mediated HSC activation. CD147 over-expression promoted HSC migration and accelerated TGF-β1-induced cell contraction. Phosphorylation of Smad2 and Smad3 in cooperation with Smad4 mediated the TGF-β1-regulated CD147 expression. Smad4 activated the transcription by direct interaction with CD147 promoter. Meanwhile, CD147 modulated the activated phenotype of HSCs through the ERK1/2 and Sp1 which up-regulated α-SMA, collagen I, and TGF-β1 synthesis. These findings indicate that TGF-β1-CD147 loop plays a key role in regulating the HSC activation and combination of TGF-β receptor inhibitor and anti-CD147 antibody might be promised to reverse fibrogenesis.

Deciphering hepatocellular responses to metabolic and oncogenic stress

Each cell type responds uniquely to stress and fractionally contributes to global and tissue-specific stress responses. Hepatocytes, liver macrophages (MΦ), and sinusoidal endothelial cells (SEC) play functionally important and interdependent roles in adaptive processes such as obesity and tumor growth. Although these cell types demonstrate significant phenotypic and functional heterogeneity, their distinctions enabling disease-specific responses remain understudied. We developed a strategy for the simultaneous isolation and quantification of these liver cell types based on antigenic cell surface marker expression. To demonstrate the utility and applicability of this technique, we quantified liver cell-specific responses to high-fat diet (HFD) or diethylnitrosamine (DEN), a liver-specific carcinogen, and found that while there was only a marginal increase in hepatocyte number, MΦ and SEC populations were quantitatively increased. Global gene expression profiling of hepatocytes, MΦ and SEC identified characteristic gene signatures that define each cell type in their distinct physiological or pathological states. Integration of hepatic gene signatures with available human obesity and liver cancer microarray data provides further insight into the cell-specific responses to metabolic or oncogenic stress. Our data reveal unique gene expression patterns that serve as molecular "fingerprints" for the cell-centric responses to pathologic stimuli in the distinct microenvironment of the liver. The technical advance highlighted in this study provides an essential resource for assessing hepatic cell-specific contributions to metabolic and oncogenic stress, information that could unveil previously unappreciated molecular mechanisms for the cellular crosstalk that underlies the continuum from metabolic disruption to obesity and ultimately hepatic cancer.

The RNA-binding protein Sam68 regulates tumor cell viability and hepatic carcinogenesis by inhibiting the transcriptional activity of FOXOs

Src associated in mitosis (Sam68; 68 kDa) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family, and has been implicated in the oncogenesis and progression of several human cancers. Our study aimed to investigated the clinicopathologic significance of Sam68 expression and its role in cell proliferation and the underlying molecular mechanism in hepatocellular carcinoma (HCC). We demonstrated that Sam68 expression was significantly increased in HCC and high expression of Sam68 was significantly associated with Edmondson grade, tumor size, tumor nodule number, HBsAg status and Ki-67 expression. The Kaplan-Meier survival curves showed that increased expression of Sam68 was correlated with poor prognosis in HCC patients and served as an independent prognostic marker of overall survival in a multivariable analysis. In addition, through serum starvation and refeeding assay, we demonstrated that Sam68 was lowly expressed in serum-starved HCC cells, and was progressively increased after serum-additioning. Furthermore, siRNA knockdown of endogenous Sam68 inhibited cell proliferation and tumourigenicity of HCC cells in vitro, through blocking the G1 to S phase transition. Moreover, we reported that the anti-proliferative effect of silencing Sam68 was accompanied with up-regulated expression of cyclin-dependent kinase inhibitors, p21(Cip1) and p27(Kip1), enhanced transactivation of FOXO factors (FOXO4), and dysreuglation of Akt/GSK-3β signaling. Taken together, these findings provide a rational framework for the progression of HCC and thereby indicated that Sam68 might be a novel and useful prognostic marker and a potential target for human HCC treatment.