The endothelin system in Morris hepatoma-7777: an endothelin receptor antagonist inhibits growth in vitro and in vivo

Diagnostic accuracy of serum endothelin-1 in patients with HCC on top of liver cirrhosis

Background

Hepatocellular carcinoma (HCC) is one of the most common cancers and one of the main causes of cancer-related deaths. As the overall survival of patients with cirrhosis has improved and the global incidence of HCC has continued to increase, strategies for the early detection of HCC are urgently needed for better prognosis. In this study, we aimed to assess the accuracy of endothelin-1 in the diagnosis of HCC in cirrhotic patients in comparison with alpha-fetoprotein (AFP) and whether it could predict its vascular spread. This is a case–control study that included 70 cirrhotic patients with or without hepatocellular carcinoma. Patients were subjected to complete medical history taking, clinical examination and laboratory investigations including serum endothelin-1, alpha-fetoprotein, abdominal ultrasound and Triphasic multi-slice computed tomography (CT; abdomen and pelvis). The outcome results obtained for endothelin-1 were used to assess its diagnostic accuracy in HCC diagnosis and the prediction of presence of vascular spread.

Results

There was a statistically significant increase in serum endothelin-1 in HCC in comparison to cirrhotic patients and normal persons (P value < 0.001). Sensitivity, specificity, and positive and negative predictive values at cut-off point of 5.2 pg/ml for HCC were 90%, 100%, 100%, and 90.9% respectively. There was no statistically significant association between serum endothelin-1 level and portal vein thrombosis in HCC (P value = 0.547).

Conclusion

Endothelin-1 has high sensitivity and specificity for diagnosis of hepatocellular carcinoma. However, it has little value for prediction of its vascular spread.

Functions of endothelin-1 in apoptosis and migration in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer mortality in China and the third leading cause of cancer mortality worldwide. The mechanisms involved in the development and progression of HCC are not well understood. In the present study, the functions of endothelin-1 (ET-1) in HCC were studied and its underlying mechanisms were investigated. ET-1, B-cell lymphoma 2 (Bcl-2), Bcl-2 related protein 4 (Bax), matrix metalloproteinase (MMP)-2 and MMP-9 expression was measured by reverse transcription-quantitative polymerase chain reaction and western blotting. Cell proliferation was measured via Cell Counting kit-8 assay. Flow cytometry was performed for cell cycle and apoptosis analysis. Migration was measured via Transwell assay. The results demonstrated that ET-1 expression significantly increased in HCC tissues compared with the normal tissues of patients in The Cancer Genome Atlas dataset (P<0.01). Furthermore, downregulation of ET-1 was able to significantly inhibit cell proliferation and growth in vitro (P<0.01) and in vivo (P<0.01), and induce cell cycle arrest (P<0.05) and apoptosis (P<0.01) in the HCC SMMC-7721 cell line. Bioinformatics analysis demonstrated that the cell apoptosis signaling pathway was activated by ET-1. The ratio of B-cell lymphoma (Bcl-2) -related protein 4 (Bax)/Bcl-2 was significantly increased by downregulation of ET-1 (P<0.01). ET-1 downregulation also inhibited migration of SMMC-7721 cells (P<0.05) via decreasing levels of matrix metalloproteinase (MMP) -2 (P<0.05) and MMP-9 (P>0.05). These results suggest that ET-1 may be able to affect the apoptosis and migration of HCC cells via modulation of the Bax/Bcl-2 ratio and expression levels of MMP-2 and MMP-9, which indicates that ET-1 maybe a potential novel target for HCC treatment.

Overexpression of endothelin 1 triggers hepatocarcinogenesis in zebrafish and promotes cell proliferation and migration through the AKT pathway

Hepatocarcinogenesis commonly involves the gradual progression from hepatitis to fibrosis and cirrhosis, and ultimately to hepatocellular carcinoma (HCC). Endothelin 1 (Edn1) has been identified as a gene that is significantly up-regulated in HBx-induced HCC in mice. In this study, we further investigated the role of edn1 in hepatocarcinogenesis using a transgenic zebrafish model and a cell culture system. Liver-specific edn1 expression caused steatosis, fibrosis, glycogen accumulation, bile duct dilation, hyperplasia, and HCC in zebrafish. Overexpression of EDN1 in 293T cells enhanced cell proliferation and cell migration in in vitro and xenotransplantation assays and was accompanied with up-regulation of several cell cycle/proliferation- and migration-specific genes. Furthermore, expression of the unfolded protein response (UPR) pathway-related mediators, such as spliced XBP1, ATF6, IRE1, and PERK, was also up-regulated at both the RNA and protein levels. In the presence of an EDN1 inhibitor or an AKT inhibitor, these increases were diminished and the EDN1-induced migration ability also was disappeared, suggesting that the EDN1 effects act through activation of the AKT pathway to enhance the UPR and subsequently activate the expression of downstream genes. Additionally, p-AKT is enhanced in the edn1 transgenic fish compared to the GFP-mCherry control. The micro RNA miR-1 was found to inhibit the expression of EDN1. We also observed an inverse correlation between EDN1 and miR-1 expression in HCC patients. In conclusion, our data suggest that EDN1 plays an important role in HCC progression by activating the PI3K/AKT pathway and is regulated by miR-1.

MicroRNA-1 inhibits proliferation of hepatocarcinoma cells by targeting endothelin-1

AIMS

MicroRNA-1 (miR-1) has been demonstrated as a tumor-suppressive miRNA, which shows a down-regulated pattern in several human malignancies including hepatocellular carcinoma (HCC). However, the pathophysiologic roles of miR-1 and their mechanisms in HCC tumorigenesis are still not totally elucidated.

MAIN METHODS

Pre-miR-1 was cloned into pSuper plasmid to overexpress the miR-1 in hepatoma cells. Real-time PCR and Western blot were applied to detect miR-1, ET-1 mRNA and protein levels respectively. Dual luciferase reporter assay was conducted to investigate the binding site of miR-1 on 3'UTR of ET-1 mRNA. Proliferation of hepatoma cells was evaluated by MTT assay.

KEY FINDINGS

We observed that over-expression of miR-1 by miRNA-expressing plasmid transfection in HepG2 and Hep3B cells significantly reduced the proliferation of these cells. To explore the mechanism, we examined the potential target genes of miR-1 by bioinformatics. A potent mitogen, Endothelin-1 (ET-1), attracted our attention. Elevated expression of ET-1 but reduced miR-1 level was detected both in human liver cancer tissues and in hepatoma cell lines using Western Blot and miRNA real-time PCR respectively. By the over-expression and inhibition of miR-1 in HepG2 and Hep3B, we confirmed that miR-1 negatively regulated ET-1 expression in hepatoma cells. A luciferase reporter assay showed that miR-1 regulation was established by pairing to a complementary binding site within the ET-1 3'UTR. Finally, attenuated proliferation of hepatoma cells by over-expression of miR-1 could be partially restored by exogenous ET-1 treatment.

SIGNIFICANCE

Our findings demonstrate that miR-1 could inhibit ET-1 expression to attenuate the proliferation of hepatoma cells.

Identification of the common regulators for hepatocellular carcinoma induced by hepatitis B virus X antigen in a mouse model

Hepatitis B virus X antigen plays an important role in the development of human hepatocellular carcinoma (HCC). The key regulators controlling the temporal downstream gene expression for HCC progression remains unknown. In this study, we took advantage of systems biology approach and analyzed the microarray data of the HBx transgenic mouse as a screening process to identify the differentially expressed genes and applied the software Pathway Studio to identify potential pathways and regulators involved in HCC. Using subnetwork enrichment analysis, we identified five common regulator genes: EDN1, BMP7, BMP4, SPIB and SRC. Upregulation of the common regulators was validated in the other independent HBx transgenic mouse lines. Furthermore, we verified the correlation of their RNA expression levels by using the human HCC samples, and their protein levels by using the human liver disease tissue arrays. EDN1, bone morphogenetic protein (BMP) 4 and BMP7 were upregulated in cirrhosis, BMP4, BMP7 and SRC were further upregulated in hepatocellular or cholangiocellular carcinoma samples. The trend of increasing expression of the common regulators correlates well with the progression of human liver cancer. Overexpression of the common regulators increases the cell viability, promotes migration and invasiveness and enhances the colony formation ability in Hep3B cells. Our approach allows us to identify the critical genes in hepatocarcinogenesis in an HBx-induced mouse model. The validation of the gene expressions in the liver cancer of human patients and their cellular function assays suggests that the identified common regulators may serve as useful molecular targets for the early-stage diagnosis or therapy for HCC.

Hormonal, hypothalamic and striatal responses to reduced body weight gain are attenuated in anorectic rats bearing small tumors

Lack of compensatory or even reduced food intake is frequently observed in weight-losing cancer patients and contributes to increased morbidity and mortality. Our previous work has shown increased transcription factor expression in the hypothalamus and ventral striatum of anorectic rats bearing small tumors. mRNA expression of molecules known to be involved in pathways regulating appetite in these structures was therefore assessed in this study. Given that pain, pro-inflammatory cytokines and metabolic hormones can modify food intake, spinal cord cellular activation patterns and plasma concentrations of cytokines and hormones were also studied. Morris hepatoma 7777 cells injected subcutaneously in Buffalo rats provoked a 10% lower body weight and 15% reduction in food intake compared to free-feeding tumor-free animals 4 weeks later when the tumor represented 1-2% of body mass. No differences in spinal cord activation patterns or plasma concentration of pro-inflammatory cytokines were observed between groups. However, the changes in plasma ghrelin and leptin concentrations found in food-restricted weight-matched rats in comparison to ad libitum-fed animals did not occur in anorectic tumor-bearing animals. Real-time PCR showed that tumor-bearing rats did not display the increase in hypothalamic agouti-related peptide mRNA observed in food-restricted weight-matched animals. In addition, microarray analysis and real-time PCR revealed increased ventral striatal prostaglandin D synthase expression in food-restricted animals compared to anorectic tumor-bearing rats. These findings indicate that blunted hypothalamic AgRP mRNA expression, probably as a consequence of relatively high leptin and low ghrelin concentrations, and reduced ventral striatal prostaglandin D synthesis play a role in maintaining cancer-associated anorexia.

T(2) relaxation times of (13)C metabolites in a rat hepatocellular carcinoma model measured in vivo using (13)C-MRS of hyperpolarized [1-(13)C]pyruvate

A single-voxel Carr-Purcell-Meibloom-Gill sequence was developed to measure localized T(2) relaxation times of (13)C-labeled metabolites in vivo for the first time. Following hyperpolarized [1-(13)C]pyruvate injections, pyruvate and its metabolic products, alanine and lactate, were observed in the liver of five rats with hepatocellular carcinoma and five healthy control rats. The T(2) relaxation times of alanine and lactate were both significantly longer in HCC tumors than in normal livers (p < 0.002). The HCC tumors also showed significantly higher alanine signal relative to the total (13)C signal than normal livers (p < 0.006). The intra- and inter-subject variations of the alanine T(2) relaxation time were 11% and 13%, respectively. The intra- and inter-subject variations of the lactate T(2) relaxation time were 6% and 7%, respectively. The intra-subject variability of alanine to total carbon ratio was 16% and the inter-subject variability 28%. The intra-subject variability of lactate to total carbon ratio was 14% and the inter-subject variability 20%. The study results show that the signal level and relaxivity of [1-(13)C]alanine may be promising biomarkers for HCC tumors. Its diagnostic values in HCC staging and treatment monitoring are yet to be explored.