Long noncoding RNA ZEB1-AS1 attenuates ferroptosis of gastric cancer cells through modulating miR-429/BGN axis

Gastric cancer (GC) is the fifth utmost common malignant cancer type globally, in which ferroptosis acts a critical function in the progress of GC. Long noncoding RNA ZEB1-AS1 has been recognized in numerous cancers, but the role of ZEB1-AS1 in ferroptosis remains obscure. Hence, we investigated the efficacy of ZEB1-AS1 on ferroptosis of GC cells. The cell growth and viability were analyzed via cell counting kit assay and xenograft tumor model in vivo and in vitro, respectively. The RNA and protein expression were measured by qRT-PCR and western blot analysis assay, respectively. The levels of Fe²⁺, malondialdehyde (MDA), and lipid reactive oxygen species (ROS) were tested to determine ferroptosis. The erastin and RSL3 were used to induce ferroptosis. The mechanism was analyzed via luciferase reporter gene and RIP assays. The treatment of ferroptosis inducer Erastin and RSL3 suppressed the viability of GC cells and the ZEB1-AS1 overexpression rescued the phenotype in the cells. The levels of Fe²⁺, MDA, and ROS were enhanced through the depletion of ZEB1-AS1 in Erastin/RSL3 treated GC cells. ZEB1-AS1 directly sponged miR-429 in GC cells and miR-429 targeted BGN in GC cells, and the inhibition of miR-429 rescued ZEB1-AS1 depletion-inhibited BGN expression. We validated that miR-429 induced and BGN-repressed ferroptosis in cancer cells. The BGN overexpression and miR-429 suppression could reverse the efficacy of ZEB1-AS1 on proliferation and ferroptosis in cancer cells. The expression of ZEB1-AS1 and BGN was enhanced and miR-429 expression was decreased in clinical GC tissues. ZEB1-AS1 attenuated ferroptosis of cancer cells by modulating miR-429/BGN axis.     

Upregulated microRNA-29a by hepatitis B virus X protein enhances hepatoma cell migration by targeting PTEN in cell culture model

Hepatitis B virus X protein (HBx) plays important roles in the development of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) contribute to cancer development by acting as oncogenes or tumor suppressors. Previously, we reported that HBx was able to promote the migration of hepatoma HepG2 cells. However, the regulation of miRNAs in the development of HBV-related HCC is poorly understood. In the present study, we reported that miR-29a was a novel regulator of migration of hepatoma cells mediated by HBx. Our data showed that the expression of miR-29a was dramatically increased in p21-HBx transgenic mice, HBx-transfected hepatoma HepG2-X (or H7402-X) cells and HepG2.2.15 cells that constitutively replicate HBV. However, our data showed that miR-29a was upregulated in 4 of the 11 clinical HCC samples. We found that the overexpression of miR-29a promoted the migration of HepG2 cells, while a specific miR-29a inhibitor could partially abolish the enhanced migration of HepG2-X cells. Moreover, we identified PTEN was one of the target genes of miR-29a in HepG2 cells. The deletion of the miR-29a-binding site was able to abolish the role of miR-29a in suppression of luciferase activity of the PTEN 3'UTR reporter. Meanwhile, the overexpression of PTEN was able to reverse the promoted migration of HepG2 cells mediated by miR-29a. Moreover, our data showed that the modulation of Akt phosphorylation, a downstream factor of PTEN, was involved in the cell migration enhanced by miR-29a, suggesting that miR-29a is responsible for the cell migration through its target gene PTEN. Thus, we conclude that miR-29a is involved in the regulation of migration of hepatoma cells mediated by HBx through PTEN in cell culture model.     

Increased expression of N-acetylglucosaminyltransferase-V in human hepatoma cells by retinoic acid and 1alpha,25-dihydroxyvitamin D3

UDP-N-acetylglucosamine: alpha-6-D-mannoside beta-1,6N-acetylglucosaminyltransferase-V activities were determined in human hepatoma cell lines of Hep3B and HepG2, and also compared with those of normal liver tissues and primary hepatocytes. When GlcNAcbeta1-2Manalpha1-3(GlcNAcbeta1-2Manalpha1-4)(Manbeta1-4GlcNAc-2-amino pyridine (GlcN,GlcN-biant-PA) and UDP-GlcNAc were used as substrates, the enzymes displayed optimum temperatures of 50 degrees C, optimum pHs of 6.5 in each case, K(m) values for UDP-GlcNAc to be 5.8 (Hep3B) and 4.5 mM (HepG2) and K(m) values for GlcN,GlcN-biant-PA (mM) to be 1.28 (Hep3B) and 2.4 (HepG2). This indicates that values of Hep3B GlcNAc-transferase-V were distinguishable with HepG2 enzyme. Furthermore, Hep3B enzyme in membrane fraction showed about 1.5-fold higher specific activity (1.423 pmol/(h mg) than that (1.066 pmol/(h mg)) of HepG2. Normal hepatocytes are characterized by very low level of GlcNAc-transferase-V activity whereas hepatoma cells contained high activities. Treatment of hepatoma cells with retinoic acid and 1alpha,2,5-dihydroxyvitamin D(3) (Vit-D(3)) resulted in an increase in GlcNAc-transferase-V activity, while treatment with dimethyl sulfoxide and cytosine-arabinoside resulted in decrease in the enzyme activity. Although retinoic acid (RA) treated cells shows a changed GlcNAc-transferase-V mRNA expression, expression of marker proteins such as alpha-fetoprotein and albumin was not changed. This is the first demonstration of GlcNAc-transferase-V activity in RA and Vit-D(3)-treated hepatoma cell lines.     

Acetaminophen sensitizing erastin-induced ferroptosis via modulation of Nrf2/heme oxygenase-1 signaling pathway in non-small-cell lung cancer

Growing evidence confirms that ferroptosis plays an important role in tumor growth inhibition. However, some non-small-cell lung cancer (NSCLC) cell lines are less sensitive to erastin-induced ferroptotic cell death. Elucidating the mechanism of resistance of cancer cells to erastin-induced ferroptosis and increasing the sensitivity of cancer cells to erastin need to be addressed. In our experiment, erastin and acetaminophen (APAP) cotreatment inhibited NSCLC cell viability and promoted ferroptosis and apoptosis, accompanied with attenuation of glutathione and ectopic increases in lipid peroxides. Erastin and APAP promoted NSCLC cell death by regulating nucleus translocation of nuclear factor erythroid 2-related factor 2 (Nrf2); and the ferroptosis induced by erastin and APAP was abrogated by bardoxolone methyl (BM) with less generation of reactive oxygen species and malondialdehyde. As a downstream gene of Nrf2, heme oxygenase-1 expression decreased significantly with the cotreatment of erastin and APAP, which could be rescued by BM. In vivo experiment showed that the combination of erastin and APAP had a synergic therapeutic effect on xenograft of lung cancer. In short, the present study develops a new effective treatment for NSCLC by synergizing erastin and APAP to induce ferroptosis.     

ATP citrate lyase inhibitor triggers endoplasmic reticulum stress to induce hepatocellular carcinoma cell apoptosis via p-eIF2α/ATF4/CHOP axis

ATP citrate lyase (ACLY), a key enzyme in the metabolic reprogramming of many cancers, is widely expressed in various mammalian tissues. This study aimed to evaluate the effects and mechanisms of ACLY and its inhibitor BMS-303141 on hepatocellular carcinoma (HCC). In this study, ACLY was highly expressed in HCC tissues, especially in HepG2 and Huh7 cells, but was down-regulated in Hep3B and HCC-LM3 cells. Besides, ACLY knockdown inhibited HepG2 proliferation and clone formation, while opposite result was noticed in HCC-LM3 cells with ACLY overexpression. Moreover, ACLY knockdown impeded the migration and invasion abilities of HepG2 cells. Similarly, BMS-303141 suppressed HepG2 and Huh-7 cell proliferation. The p-eIF2α, ATF4, CHOP p-IRE1α, sXBP1 and p-PERK were activated in HepG2 cells stimulated by BMS-303141. In cells where ER stress was induced, ATF4 was involved in BMS-303141-mediated cell death procession, and ATF4 knockdown reduced HCC cell apoptosis stimulated by BMS-303141. In a mouse xenograft model, combined treatment with BMS-303141 and sorafenib reduced HepG2 tumour volume and weight. In addition, ACLY expression was associated with HCC metastasis and tumour-node-metastases staging. Survival analysis and Cox proportional hazards regression model showed that overall survival was lower in HCC patients with high ACLY expression; AFP level, TNM staging, tumour size and ACLY expression level were independent risk factors affecting their overall survival. In conclusion, ACLY might represent a promising target in which BMS-303141 could induce ER stress and activate p-eIF2α/ATF4/CHOP axis to promote apoptosis of HCC cells, and synergized with sorafenib to enhance the efficacy of HCC treatment.     

STAT1 plays an essential role in LPS/D-galactosamine-induced liver apoptosis and injury

Interferon-gamma (IFN-gamma) has been implicated in liver damage in animal models and chronic hepatitis C infection; however, the underlying mechanism is not clear. Here we examined the role of STAT1, a key signaling molecule for IFN-gamma, in a model of murine hepatitis induced by the injection of LPS/D-galactosamine and in human hepatoma Hep3B cells. STAT1 is rapidly activated and highly induced after injection of LPS/D-galactosamine. Both overexpression of STAT1 and hepatocellular damage are located in the same pericentral region. Disruption of the STAT1 gene abolishes LPS/D-galactosamine-induced liver injury. Studies from IFN-gamma-deficient mice indicate that IFN-gamma is the major cytokine responsible for activation and hyperexpression of STAT1 in LPS/D-galactosamine-induced hepatitis. Hep3B cells overexpressing dominant negative STAT1 are resistant to IFN-gamma and IFN-gamma + TNF-alpha-induced cell death, whereas Hep3B cells overexpressing wild-type STAT1 are more susceptible to cell death. Taken together, these findings suggest that STAT1 plays an essential role in LPS/D-galactosamine-induced liver apoptosis and injury.     

p53 is not necessary for nuclear translocation of GAPDH during NO-induced apoptosis

Aberrant GAPDH expression following S-nitrosoglutathione (GSNO) treatment was compared in HepG2 cells, which express functional p53, and Hep3B cells, which lack functional p53. The results of Western blotting and fluorescent immunocytochemistry revealed that nuclear translocation and accumulation of GAPDH occur in both HepG2 and Hep3B cells. This finding suggests that p53 may not be necessary for the GSNO-induced translocation of GAPDH to the nucleus during apoptotic cell death in hepatoma cells.     

Paeoniae Radix,a Chinese herbal extract,inhibit hepatoma cells growth by inducing apoptosis in a p53 independent pathway

Paeoniae Radix (PR) is the root of traditional Chinese Herb named Paeonia lactiflora Pallas, which is commonly used to treat liver diseases in China for centuries. Several earlier studies have indicated that PR has anticancer growth activities, however the mechanism underlying these activities was unclear and remained to be elucidated. In this study, we evaluated the molecular mechanism of the effect of PR on human hepatoma cell lines, HepG2 and Hep3B. Our results showed that the water-extract of Paeoniae Radix (PRE) had inhibitory effect on the growth of both HepG2 and Hep3B cell lines. The induction of internucleosomal DNA fragmentation and chromatin condensation appearance, and accumulation of sub-G1 phase of cell cycle profile in PRE treated hepatoma cells evidenced that the cytotoxicity of PRE to the hepatoma cells is through activation of the cell death program, apoptosis. The activation of apoptosis by PRE is independent of the p53 pathway as Hep3B cell is p53-deficient. In addition, the differential gene expression of PRE treated HepG2 was examined by cDNA microarray technology and RT-PCR analysis. We found that the gene expression of BNIP3 was up-regulated while ZK1, RAD23B, and HSPD1 were down-regulated during early apoptosis of the hepatoma cell mediated by PRE. The elucidation of the drug targets of PR on inhibition of tumor cells growth should enable further development of PR for liver cancer therapy.     

miR-146a/b在Hep3B细胞中的表达及上下游调控机制探讨

目的：探究miR-146a/b在Hep3B的表达及其上游调控机制和下游靶标蛋白。方法：MTT法检测人正常肝细胞株LO2和人肝癌细胞株HepG2、Hep3B的增殖活性。分别提取3个细胞的总RNA和蛋白,应用RT-qPCR和蛋白印记法分别检测细胞株中miR-146a/b的表达和细胞外调节激酶1/2（ERK）、磷酸化ERK 1/2（p-ERK1/2）、磷酸化蛋白激酶B（p-AKT）、NF-κB抑制蛋白α亚基（IκBα）、白介素1受体关联激酶1（IRAK1）、肿瘤坏死因子受体相关蛋白6（TRAF6）的蛋白水平。用抑制剂分别抑制Hep3B细胞PI3K、AKT、ERK、NF-κB信号分子的活性并检测miR-146a/b的表达水平及IRAK1、TRAF6的蛋白水平。结果Hep3B细胞增殖活力和miR-146a/b表达水平显著高于LO2和HepG2（P<0.01）。蛋白印记结果显示,以LO2为对照组,Hep3B细胞的p-ERK1、ERK1、p-AKT、IκB的蛋白水平明显升高,分别为LO2的10.87、24.68、6.67和1.92倍;IRAK1、TRAF6的蛋白水平明显降低,分别为LO2的0.23和0.003倍。与LO2细胞相比,HepG2细胞的IκB和IRAK1蛋白表达明显升高,分别为LO2的4.46和2.69倍。抑制Hep3B细胞的PI3K和AKT活性12 h和24 h,miR-146a和miR-146b的表达水平显著降低（P<0.05）;抑制ERK和NF-κB的活性12 h和24 h,miR-146a/b的表达水平没有显著变化。抑制PI3K、AKT、ERK、NF-κB信号通路活性均可上调TRAF6和下调IRAK1的蛋白表达水平。结论：在恶化程度较高的Hep3B细胞中,PI3K/AKT可通过上调miR-146a/b的表达进而下调TRAF6的蛋白水平,这一机制为肝肿瘤发生发展的机理研究提供了重要线索。     

Screening and identification of a novel target specific for hepatoma cell line HepG2 from the FliTrx bacterial peptide library

To explore new targets for hepatoma research, we used a surface display library to screen novel tumor cell-specific peptides. The bacterial FliTrx system was screened with living normal liver cell line L02 and hepatoma cell line HepG2 successively to search for hepatoma-specific peptides. Three clones (Hep1, Hep2, and Hep3) were identified to be specific to HepG2 compared with L02 and other cancer cell lines. Three-dimensional structural prediction proved that peptides inserted into the active site of Escherichia coli thioredoxin (TrxA) formed certain loop structures protruding out of the surface. Western blot analysis showed that FliC/TrxA-peptide fusion proteins could be directly used to detect HepG2 cells. Three different FliC/TrxA-peptide fusion proteins targeted the same molecule, at approximately 140 kDa, on HepG2 cells. This work presented for the first time the application of the FliTrx library in screening living cells. Three peptides were obtained that could be potential candidates for targeted liver cancer therapy.     

Vitamin D and melatonin protect the cell’s viability and ameliorate the CCl4 induced cytotoxicity in HepG2 and Hep3B hepatoma cell lines

Carbon tetrachloride (CCl₄) is widely used to induce liver toxicity in in vitro/in vivo models. Lipid peroxidation (LPO) begins with toxicity and affects cell viability. Recently, the beneficial effects of melatonin and Vitamin D on cell proliferation in human normal and cancer cells were found. This study was planned to evaluate antioxidant and cytoprotective activity of melatonin and Vitamin D in CCl₄ induced cytotoxicity in HepG2 and Hep3B hepatoma cell lines. Based on the cytotoxicity assay, melatonin and Vitamin D were evaluated for cytotoprotective potential against CCl₄ induced toxicity in HepG2 and Hep3B liver cell lines by monitoring cell viability, LPO and glutathione (GSH) level. Different dosages of CCl₄ (0.1, 0.2, 0.3 and 0.4 % v/v) were applied to HepG2 and Hep3B cells in order to determine the most toxic dosage of it in a time dependent manner. The same experiments were repeated with exogenously applied melatonin (MEL) and Vitamin D to groups treated with/without CCL₄. Cell viability was determined with MTT measurements at the 2nd, 24th and 48th h. GSH content and Malondialdehyde levels were measured from the cell lysates. As a result, both melatonin and Vitamin D administration during CCl₄ exposure protected liver cells from CCl₄ induced cell damage. Increase in LPO and decrease in GSH were found in the CCl₄ groups of both cells. Contrary to these results administration of MEL and Vitamin D on cells exhibited results similar to the control groups. Therefore, melatonin and Vitamin D might be a promising therapeutic agent in several toxic hepatic diseases.     

Induction of apoptosis in p53-deficient human hepatoma cell line by wild-type p53 gene transduction: inhibition by antioxidant

We investigated the role of wild-type (wt)-p53 as an inducer of apoptotic cell death in human hepatoma cell lines. Following the retrovirus-mediated transduction of the wt-p53 gene, Hep3B cells lacking the endogenous p53 expression began to die through apoptosis in 4 h. They showed a maximal apoptotic death at 12 h, whereas HepG2 cells expressing endogenous p53 did not. However, the transduction of the wt-p53 gene elicited growth suppression of both Hep3B and HepG2 cells. P21(WAF1/CIP1), a p53-inducible cell cycle inhibitor, was induced, not only in Hep3B cells undergoing apoptosis, but also in HepG2 cells. The kinetics of the p21(WAF1/CIP1) induction, DNA fragmentation, and growth suppression of the Hep3B cells showed that DNA fragmentation and growth suppression progressed rapidly following p21(WAF1/CIP1) accumulation. N-acetyl-cysteine or glutathione, potent antioxidants, strongly inhibited the DNA fragmentation, but did not reduce the elevated level of p21(WAF1/CIP1). These findings suggested that p21(WAF1/CIP1) was not a critical mediator for the execution of p53-mediated apoptosis, although it contributed to the growth inhibition of cells undergoing apoptosis. Furthermore, p53-mediated apoptosis could be repressed by antioxidants.     

A solution hybridization/RNase protection assay with riboprobes to determine absolute levels of apoB, A-I, and E mRNA in human hepatoma cell lines

A solution hybridization/RNase protection assay with riboprobes was developed to quantitate apolipoprotein mRNA concentrations. Previously, radiolabeled DNA probes have been used in solution hybridization/S1 nuclease protection assays for this purpose. The new assay requires less time for probe preparation and hybridization compared to previous assays. In addition, the vector used for riboprobe preparation can also be used to conveniently produce cRNA required to generate the standard curve to quantitate absolute apolipoprotein mRNA levels. The solution hybridization RNase protection assay was used to quantitate apoB, A-I, and E mRNA levels in four human hepatoma cell lines, HepG2, Hep3B, WRL-68, SK-Hep2. HepG2 and Hep3B, but not WRL-68 and SK-Hep2 cells had concentrations of all three apolipoprotein mRNAs comparable to liver in vivo. These data suggest that HepG2 and Hep3B are suitable models to study liver specific apolipoprotein gene expression.     

LncRNA DGCR5 represses the development of hepatocellular carcinoma by targeting the miR-346/KLF14 axis

Long non-coding RNAs (lncRNAs) are a class of regulatory noncoding RNAs. Emerging evidence highlights the critical roles of lncRNAs in the progression of hepatocellular carcinoma (HCC). Although many lncRNAs have been identified in the development of HCC, the association between DiGeorge syndrome critical region gene 5 (DGCR5) and HCC remains unclear. In the current study, we focused on the biological role of DGCR5 in HCC. We observed that DGCR5 was decreased in HCC cells, including SMCC7721, Hep3B, HepG2, MHCC-97L, MHCC-97H, and SNU449 hepatocellular carcinoma cells, compared with the normal human liver cell line THLE-3 normal human liver cells. In addition, DGCR5 overexpression could repress HCC cell growth, migration, and invasion considerably. Increasing studies have indicated the interactions between lncRNAs and microRNAs. MicroRNAs are endogenous small noncoding RNAs and they can play important roles in tumorigenesis. MicroRNA 346 (miR-346) has been demonstrated in various human cancer types, including HCC. MiR-346 was found to be increased in HCC cells and DGCR5 can act as a sponge of miR-346 to modulate the progression of HCC. The binding correlation between DGCR5 and miR-346 was validated in our research. Subsequently, Krüppel-like factor 14 (KLF14) was predicted as a downstream target of miR-346 and miR-346 can induce the development of HCC by inhibiting KLF14. Finally, we proved that DGCR5 can rescue the inhibited levels of KLF14 repressed by miR-346 mimics in MHCC-97H and Hep3B cells. Taken together, it was indicated in our study that DGCR5 can restrain the progression of HCC through sponging miR-346 and modulating KLF14 in vitro.