Targeting PCDH20 gene by microRNA-122 confers 5-FU resistance in hepatic carcinoma

Drug resistance is one of the main hurdles for the successful treatment of hepatic carcinoma. However, the detailed mechanisms underlying resistance remain largely unknown and therapeutic approaches are limited. In the present study, we show that miR-122 confers resistance to 5-fluorouracil induced hepatocellular carcinoma cell apoptosis in vitro and reduces the potency of 5-fluorouracil in the inhibition of tumor growth in a mouse xenograft model in vivo. Further studies indicate that miR-122 modulates drug resistance through down-regulation of expression of PCDH20, which belongs to the protocadherin gene family and negatively regulates Akt activation. Knockdown of PCDH20 expression increases Akt phosphorylation, which leads to elevated mTOR activity and enhanced 5-fluorouracil resistance; whereas rescue of PCDH20 expression in miR-122-expressing cells decreases Akt and mTOR phosphorylation, re-sensitizing hepatocellular carcinoma cell to 5-fluorouracil induced apoptosis. Moreover, a specific and potent Akt inhibitor reverses miR-122-conferred 5-fluorouracil resistance. These findings indicate that the miR-122/PCDH20/Akt/mTOR signaling axis has an important role in mediating response to chemotherapy in human hepatocellular carcinoma. A major implication of our study is that inhibition of miR-122 or restoration of PCDH20 expression may have significant therapeutic potential to overcome drug resistance in hepatocellular carcinoma and that the combined use of an Akt inhibitor with 5-fluorouracil may increase efficacy in liver cancer treatment.

Elevating microRNA-122 in blood improves outcomes after temporary middle cerebral artery occlusion in rats

Because our recent studies have demonstrated that miR-122 decreased in whole blood of patients and in whole blood of rats following ischemic stroke, we tested whether elevating blood miR-122 would improve stroke outcomes in rats. Young adult rats were subjected to a temporary middle cerebral artery occlusion (MCAO) or sham operation. A polyethylene glycol-liposome-based transfection system was used to administer a miR-122 mimic after MCAO. Neurological deficits, brain infarction, brain vessel integrity, adhesion molecule expression and expression of miR-122 target and indirect-target genes were examined in blood at 24 h after MCAO with or without miR-122 treatment. miR-122 decreased in blood after MCAO, whereas miR-122 mimic elevated miR-122 in blood 24 h after MCAO. Intravenous but not intracerebroventricular injection of miR-122 mimic decreased neurological deficits and brain infarction, attenuated ICAM-1 expression, and maintained vessel integrity after MCAO. The miR-122 mimic also down-regulated direct target genes (e.g. Vcam1, Nos2, Pla2g2a) and indirect target genes (e.g. Alox5, Itga2b, Timp3, Il1b, Il2, Mmp8) in blood after MCAO which are predicted to affect cell adhesion, diapedesis, leukocyte extravasation, eicosanoid and atherosclerosis signaling. The data show that elevating miR-122 improves stroke outcomes and we postulate this occurs via downregulating miR-122 target genes in blood leukocytes.

Mesenchymal stem cells deliver and release conditionally replicative adenovirus depending on hepatic differentiation to eliminate hepatocellular carcinoma cells specifically

Currently, it is a key challenge to remove the postsurgical residuals and metastasis of hepatocellular carcinoma (HCC). Oncolytic adenoviral virotherapy is an attractive treatment modality for cancer; however, the difficulty remains regarding its intravenous administration. The aim of this study was to develop a targeted therapeutic system which has great potential to overcome the postsurgical residuals and metastasis of HCC. In this system, we developed a conditionally replicative adenovirus (CRAd) loaded on human umbilical cord-derived mesenchymal stem cells (HUMSCs), in which the CRAd contained an adenovirus E1A gene dual regulated by α-fetoprotein promoter and microRNA-122 target sequence. When HUMSCs homed to the tumor sites and differentiated into hepatocyte-like cells within tumor microenvironment, the CRAds were packaged and released strictly to the local tumor. Subsequently, the CRAd lysed tumor cells selectively with the post-infection regulation. The study showed the specific oncolytic effect of the CRAd to HCC cells and the production of the CRAd by differentiated HUMSCs in vitro. Furthermore, we proved the hepatocyte-like transformation of HUMSC in the microenvironment of orthotopic or heterotopic hepatoma. Finally, this therapeutic system exhibited dramatic tumor inhibition on both orthotopic and subcutaneous hepatic xenograft tumor model mice with less toxicity on normal organs. The study results have demonstrated that this targeted therapeutic strategy is a promising method to resolve the problem of postsurgical residuals and metastasis of HCC.

Ratio of microRNA-122/155 in isoniazid-induced acute liver injury in mice

Liver injury is a major hindrance to the treatment of tuberculosis (TB) patients due to the primary side effects associated with anti-TB drugs. Several investigations have identified sensitive biomarkers for the early diagnosis of anti-TB drug-induced liver injury (ADLI), including the use of microRNAs (miRNAs/miRs). However, the association between miR-122/155 and ADLI remains unknown. Thus, the present study used reverse transcription-quantitative polymerase chain reaction to observe changes in tissue miR-122/155 expression levels during the course of liver injury in mice. Liver injury was induced by the administration of isoniazid (INH), a first-line anti-TB drug. miR-122/155 expression levels were quantified at seven time points throughout 1 day (0.25, 0.75, 1.5, 6, 12, 18 and 24 h) based on the pharmacokinetics of INH in mice. Notably, over the timecourse of INH-induced liver injury, the tissue miR-122 expression level significantly decreased at 0.25 h, which is the peak concentration time of INH, compared with the control group (P<0.05). The change was more rapid than that of the serum aminotransferase and miR-155, which were significantly increased at 0.75 h. In addition, the pathological score correlated with the ratio of miR-122/miR-155 (r=−0.779; P<0.01). In conclusion, the miR-122/155 ratio may be utilized as a sensitive biomarker for ADLI, which could contribute to the early diagnosis of patients following anti-TB treatment.

Downregulation of microRNA-122 promotes proliferation, migration, and invasion of human hepatocellular carcinoma cells by activating epithelial-mesenchymal transition

Objective

To investigate the effects of microRNA-122 (miR-122) on proliferation, migration, and invasion in human hepatocellular carcinoma (HCC) cells by activating epithelial–mesenchymal transition (EMT) pathways.

Methods

miR-122 mimics, miR-122 inhibitors, relevant control oligonucleotides, and Wnt1 were transfected into HepG2 and huh7 cell lines which were then divided into six groups: miR-122 group, anti-miR-122 group, miR-negative control (NC) group, anti-miR-NC group, miR-122 + Wnt1 group, and miR-122 + vector group. The miR-122 expressions and mRNA expressions of Wnt1 and EMT-related genes (E-cadherin, vimentin, β-cadherin, and N-cadherin) were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression levels of Wnt1, E-cadherin, vimentin, β-cadherin, and N-cadherin were measured by Western blot. Cell proliferation, migration, and invasion were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, wound-healing assay, and Transwell assay, respectively.

Results

Dual luciferase reporter gene results showed that Wnt1 is a direct target gene of miR-122 in both HepG2 and huh7 cell lines. Compared to miR-NC, anti-miR-NC, and miR-122 + Wnt1 groups, miR-122 expression was markedly higher in the miR-122 group and miR-122 + vector group, but was sharply decreased in anti-miR-122 group (both P<0.05), and the mRNA and protein levels of Wnt1, vimentin, β-cadherin, and N-cadherin decreased significantly; also E-cadherin increased, and cell proliferation, migration, and invasion decreased in the miR-122 group and miR-122 + vector group (all P<0.05), but the situation was totally reversed in the anti-miR-122 group (all P<0.05).

Conclusion

Downregulation of miR-122 promoted proliferation, migration, and invasion of human HCC cells by targeting Wnt1 and regulating Wnt/β-catenin pathway which activated the EMT pathways.

miR-122 inhibits metastasis and epithelial-mesenchymal transition of non-small-cell lung cancer cells

miR-122 may function as a novel tumor suppressor. Expression of miR-122 could suppress the proliferation of multi-kinds of human cancer cell lines. In this work, expression of miR-122 via adenoviral vector in non-small-cell lung cancer (NSCLC) cells reduces the number of invasion and migration cells. miR-122 attenuates the epithelial-mesenchymal transition process, which mediates cancer cells metastasis in NSCLC cells A549 and H460. The mechanisms data reveals that miR-122 would disrupt the epithelial-mesenchymal transition process by downregulating PI3K/AKT activation via reducing endogenous expression of insulin-like growth factor 1 receptor. These data highlight the detailed roles and potential application of miR-122 in NSCLC cells.

MicroRNA-130a inhibits HCV replication by restoring the innate immune response

Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis and hepatocellular carcinoma. Currently pegylated interferon (IFN) combined with ribavirin remains the best therapeutic approach, although patients infected with HCV genotype I may benefit from adding protease inhibitors as 'triple therapy'. MicroRNAs (miRNAs) are endogenous small noncoding RNAs that regulate gene expression and have recently been shown to play an important role in human innate immune response and as an antiviral in chimpanzees. We studied the effect of miR-130a on the HCV replication. We found that miR-130a significantly inhibits HCV replication in both HCV replicon and J6-/JFH1-infected cells. Over expression of miR-130a upregulated the expression of type I IFN (IFN-α/IFN -β), ISG15, USP18 and MxA, which are involved in innate immune response and decreased expression of miR-122, a well-defined miRNA promoting HCV production. In conclusion, miR-130a inhibits HCV replication/production by restoring host innate immune responses and/or downregulating pro-HCV miR-122. miR-130a might be a potential drug target by modulating host innate immune responses to combat HCV infection.

Alteration of the microRNA-122 regulatory network in rat models of hepatotoxicity

MicroRNAs are small RNA molecules that post-transcriptionally regulate gene expression. MicroRNA-122 is the most abundant and specific liver microRNA. Hepatotoxicity involves a significant alteration of liver gene expression. The aim of this work was to evaluate the microRNA-122 regulatory network in models of hepatotoxicity induced by thioacetamide or carbon tetrachloride. We report that the toxins decreased the expression of microRNA-122, which corresponded with an increase in two target genes: Cyclin G1 and the cationic amino acid transporter CAT-1. We found a decreased expression of its precursor, pri-microRNA-122, and of the transcription factors that specifically bind its promoter: CCAAT/enhancer-binding protein alpha, and members of the hepatocyte nuclear factor family. Therefore, microRNA-122 expression levels are under transcriptional control during hepatotoxicity. We propose that the changes observed are associated with the liver response to cope with the injury caused by the hepatotoxins, likely through a cell proliferation process to repair the damaged tissue.

Correlation between plasma miR-122 expression and liver injury induced by hepatectomy

OBJECTIVE

This study aimed to define the correlation between microRNA-122 (miR-122) expression and hepatectomy-induced liver injury in patients with hepatocellular carcinoma (HCC).

METHODS

Plasma miR-122 expression in patients with HCC and healthy age-matched controls was determined, and correlated with plasma alanine transaminase activity (ALT) and bilirubin levels preoperatively and on days 1 and 7 postoperation. Correlations between plasma miR-122 and clinicopathological characteristics at 1 day postoperation were also determined.

RESULTS

This study included 80 patients with HCC and 80 controls. Baseline expression of miR-122 mRNA and ALT in patients with HCC was significantly higher than in controls. MiR-122 expression correlated with ALT and bilirubin levels preoperatively and on days 1 and 7 postoperatively. In patients with HCC who received a block of the first hepatic portal during surgery and those with excised tumour size >5 cm, plasma miR-122 expression was significantly increased on day 1 postoperatively, compared with expression levels in those who did not receive a block and those with smaller tumours.

CONCLUSIONS

Plasma miR-122 expression is correlated with hepatectomy-induced liver injury in patients with HCC. Increase in miR-122 expression could be used as an index of such injury before and after hepatectomy in these patients.

Plasma biomarkers of liver injury and inflammation demonstrate a lack of apoptosis during obstructive cholestasis in mice

Cholestasis is a pathological common component of numerous liver diseases that results in hepatotoxicity, inflammation, and cirrhosis when untreated. While the predominant hypothesis in cholestatic liver injury remains hepatocyte apoptosis due to direct toxicity of hydrophobic bile acid exposure, recent work suggests that the injury occurs through inflammatory necrosis. In order to resolve this controversy, we used novel plasma biomarkers to assess the mechanisms of cell death during early cholestatic liver injury. C57Bl/6 mice underwent bile duct ligation (BDL) for 6-72 h, or sham operation. Another group of mice were given d-galactosamine and endotoxin as a positive control for apoptosis and inflammatory necrosis. Plasma levels of full length cytokeratin-18 (FL-K18), microRNA-122 (miR-122) and high mobility group box-1 protein (HMGB1) increased progressively after BDL with peak levels observed after 48 h. These results indicate extensive cell necrosis after BDL, which is supported by the time course of plasma alanine aminotransferase activities and histology. In contrast, plasma caspase-3 activity, cleaved caspase-3 protein and caspase-cleaved cytokeratin-18 fragments (cK18) were not elevated at any time during BDL suggesting the absence of apoptosis. In contrast, all plasma biomarkers of necrosis and apoptosis were elevated 6 h after Gal/End treatment. In addition, acetylated HMGB1, a marker for macrophage and monocyte activation, was increased as early as 12 h but mainly at 48-72 h. However, progressive neutrophil accumulation in the area of necrosis started at 6h after BDL. In conclusion, these data indicate that early cholestatic liver injury in mice is an inflammatory event, and occurs through necrosis with little evidence for apoptosis.

Targeting microRNA-122 to Treat Hepatitis C Virus Infection

An important host factor for hepatitis C virus (HCV) is microRNA-122 (miR-122). miR-122 is a liver-specific member of a family of small, non-coding RNA molecules known as microRNAs that play major roles in the regulation of gene expression by direct interaction with RNA targets. miR-122 binds directly to two sites in the 5′ untranslated region (UTR) of HCV RNA and positively regulates the viral life cycle. The mechanism by which this regulation occurs is still not fully understood. There has been a great deal of interest in potential therapeutics based on small RNAs, and targeting miR-122 to combat HCV is one of the furthest advanced. Chemical inhibitors of miR-122 can be introduced into mammals intravenously and result in potent and specific knockdown of the microRNA, with no detectable adverse effects on liver physiology. This strategy was recently applied to chimpanzees chronically infected with HCV and resulted in a sustained reduction in viral load in the animals. Inhibition of miR-122 therefore presents a very attractive novel approach to treating HCV, a virus for which improved therapeutics are urgently needed.