[miR-200a involvement in the biological behavior of hepatoma carcinoma cells by targeting the regulatory expression of mesenchymal-epithelial transition factor]

Objective: To study the regulatory effect of miR-200a on mesenchymal-epithelial transition factor (MET) and its impact on the biological behavior of hepatoma carcinoma cells. Method: A luciferase reporter assay was used to determine miR-200a's regulatory impact on MET. Human hepatoma HepG2 cells were divided into a control group, a miR-200a group, a MET overexpression group, and a co-transfection group (miR-200a+MET). After culture, cell proliferation ability, cell migration ability, apoptosis, cell invasion ability, and the expression of MET and apoptosis-related (Bcl-2, Caspase-3, Bax) proteins were detected and observed by cell counting kit-8 (CCK-8), scratch assay, Annexin V-FITC staining, transwell chambers, and western blotting. The two groups were compared using the independent sample t-test. The multiple groups were statistically analyzed using one-way ANOVA. Results: The luciferase experiment showed that miR-200a had target MET. The proliferation rate, number of invasions in cells (55.00 ± 7.21, 85.00 ± 7.94, 164.67 ± 19.22, 104.00± 12.29), scratch healing rate (28.33% ± 5.03%, 61.67% ± 4.04%, 74.67% ± 7.02%, 49.33% ± 9.02%), and expression levels of MET, Bcl-2, and Caspase-3 proteins were lower in the miR-200a group than those in the control group, MET overexpression group, and co-transfection group, while the MET overexpression group had higher indexes than the other three groups, with statistically significant differences between the groups (P <0.05). The apoptosis rate of HepG2 cells and the expression level of Bax protein were higher in the miR-200a group than those in the control group, MET overexpression group, and co-transfection group (19.25% ± 2.98%, 6.80% ± 1.15%, 3.42% ±0.76%, 9.90% ± 2.72%), while the levels of various indexes in the MIF overexpression group were lower than those in the other three groups. The control group and co-transfection group were between the two groups, and the difference between the groups was statistically significant (P <0.05). Conclusion: HepG2 cell proliferation, migration, invasion, and cell apoptosis induction can be inhibited by miR-200a, and the functional mechanism for this may be associated with the miR-200a target's ability to down-regulate MET expression in HepG2 cells.

Development of a genetically modified hepatoma cell line with heat-inducible high liver function

Hepatoma cells are a promising cell source for the construction of bioartificial liver (BAL) systems owing to their high proliferative capability. However, their low liver function compared with primary hepatocytes is a major problem. In a previous study, we established a genetically modified hepatoma cell line, Hepa/8F5, in which eight liver-enriched transcription factor (LETF) genes were transduced into mouse hepatoma Hepa1-6 cells using a drug-inducible transactivator system. These cells proliferate actively under normal culture conditions, meaning that large quantities can be prepared easily. When the overexpression of the LETFs is induced by the addition of an inducer drug, cell growth stops and cell morphology changes with concomitant high expression of liver functions. However, the liver functions largely depend on the presence of the inducer drug, which must be continuously added to maintain these enhanced functions. In the present study, we attempted to modify the method of induction of LETF overexpression in Hepa/8F5 cells to remove the requirement for continual drug addition. To this end, we constructed a system in which the artificial transactivator was transcribed and amplified under the control of a heat-shock protein promoter, and introduced the system into the genome of Hepa/8F5 cells. In our modified cell line, heat-triggered LETF expression was confirmed to induce high liver function. After drug-screening of transfected cells, we established a hepatoma cell line (Hepa/HS), which exhibited high, heat-inducible liver functions. The Hepa/HS cells may represent a new cell source for hepatic studies such as the construction of BAL systems.

Supplementary Information

The online version of this article (10.1007/s10616-021-00457-4) contains supplementary material, which is available to authorized users.

Differential effects of vitamin D3 vs vitamin D2 on cellular uptake, tissue distribution and activation of vitamin D in mice and cells

To combat vitamin D deficiency, vitamin D₃ and vitamin D₂ are commonly used as a supplement or to fortify food sources. Human data show that the response of 25-hydroxyvitamin D (25(OH)D) to supplementation with vitamin D₃ is higher than to vitamin D₂. To elucidate the metabolic route of both vitamers, we conducted a study with vitamin D-depleted mice, which were allotted into three groups (n = 12) and received equal doses of either deuterated vitamin D₃, deuterated vitamin D₂ or both for 4 weeks. To further investigate the hepatic uptake and hydroxylation of both D-vitamers to 25(OH)D, we conducted cell culture experiments with murine and human hepatoma cells (Hepa1-6 and HepG2). The vitamin D metabolite concentrations in serum, tissues and cells were analyzed by LC-MS/MS or ELISA. In mice, vitamin D₂ resulted in lower serum and tissue concentrations of vitamin D (P < 0.001) than vitamin D₃, while the group which received both D-vitamers showed values in between. Interestingly, vitamin D₂ fed mice had 1.9-times and 2.9-times higher serum concentrations of total and free 25(OH)D (P < 0.001) than mice fed vitamin D₃, while the concentration of 1,25-dihydroxyvitamin D (1,25(OH)₂D) was 1.8-times lower (P < 0.001). The gene and protein expression of enzymes, involved in the hydroxylation and renal uptake of vitamin D remained largely unaffected by the D-vitamer. In contrast to the mice data, hepatoma cells preferred vitamin D₃ for 25-hydroxylation over vitamin D₂ (P < 0.001). In general, the formation of 25(OH)D was much more pronounced in human than in murine hepatoma cells (P < 0.001). To conclude, in contrast to humans, vitamin D₂ was more efficient in increasing 25(OH)D than vitamin D₃ in mice, although this difference was not caused by a preferential hydroxylation of vitamin D₂ in the liver. The metabolic routes of D₃ and D₂ in mice differ, showing lower circulating 1,25(OH)₂D and tissue vitamin D concentrations in D₂- than in D₃-fed mice.

Vanadate inhibits transcription of the rat insulin receptor gene via a proximal sequence of the 5'flanking region

Vanadate, a protein tyrosine phosphatase inhibitor which elicits insulin-like effects, has previously been shown to inhibit expression of the insulin receptor gene at the transcriptional level in rat hepatoma cells. In an attempt to identify the DNA sequence and transcription factors potentially involved in this effect, a fragment of the proximal 5'flanking region of the IR gene (-1143/-252 upstream the ATG codon) has been cloned and functionally characterized. RNase protection allowed the identification of several transcription start sites in the conserved region of the gene, among which two major sites at -455 and -396. Upon fusion to the luciferase gene and transient transfection into hepatoma cells, the -1143/-252 fragment showed promoter activity. This was unaffected by deletion of the -1143/-761 sequence, but markedly decreased (90%) by additional deletion of the -760/-465 sequence. Treatment of hepatoma cells with vanadate led to a dose-dependent decrease in promoter activity of the 1143/-252, -760/-252 and -464/-252 constructs (change relative to untreated cells, 40, 55 and 23% at 125 μM, and 70, 85 and 62% at 250 μM, respectively). These data suggest that although the entire DNA sequence upstream the transcription start sites is probably involved in vanadate-induced inhibition, the short sequence downstream of position -464 and is sufficient for inhibition. Potential targets of vanadate are the transcription factors FoxO1 and HMGA1, two downstream targets of the insulin signaling pathway which have been shown to mediate the inhibitory effect of insulin on IR gene expression.

Effects of flavonoids from Rabdosia serra (Maxim.) Hara on proliferation, migration, and invasion of hepatocellular carcinoma cells

AIM

To investigate the effect of flavonoids from Rabdosia serra (Maxim.) Hara on the proliferation, migration, and invasion of human hepatoma HepG2 cells and explore the possible mechanisms involved.

METHODS

After HepG2 cells were treated with various concentrations of flavonoids from Rabdosia serra (Maxim.) Hara (0, 1, 5, 10, 20, or 40 μmol/L), cell viability was determined by CCK-8 assay, cell migration was examined by wound healing assay, and cell invasion was assessed by Transwell assay. Moreover, the protein expression of Notch-1, Cyclin D1, MMP-2, and MMP-9 was detected by Western blot.

RESULTS

CCK-8 assay showed that flavonoids from Rabdosia serra (Maxim.) Hara decreased HepG2 cell viability in a concentration-dependent manner, with the maximal effect observed at 20 μmol/L. Flavonoids from Rabdosia serra (Maxim.) significantly inhibited hepatoma cell migration and invasion. Furthermore, the protein expression of Notch-1, Cyclin D1, MMP-2, and MMP-9 was dramatically decreased after treatment with flavonoids from Rabdosia serra (Maxim.) Hara.

CONCLUSION

Our data demonstrate that the flavonoids from Rabdosia serra (Maxim.) Hara can effectively inhibit human hepatoma HepG2 cell proliferation, migration, and invasion possibly by inhibiting the Notch-1-MMP-2/-9 and Notch-1-Cyclin D1 signaling pathways.

Thyroid hormone regulates fibronectin expression through the activation of the hypoxia inducible factor 1

Thyroid hormones regulate gene expression via both canonical and non-canonical signaling. Hyperthyroidism is associated with elevated plasma levels of fibronectin (FN): in this study we elucidate the molecular mechanism through which triiodothyronine (T3) regulates FN and demonstrate that T3 induces FN expression via a non-canonical pathway by activating hypoxia-inducible factor-1 (HIF-1). We found that T3 treatment increased cellular and secreted FN in human hepatoma cells (HepG2) and human dermal fibroblasts (HF) via the PI3K/Akt/HIF-1 pathway. The inhibition of either Akt phosphorylation with wortmannin or HIF-1 with YC1 in both cell types prevented HIF-1α synthesis and FN positive regulation upon T3 treatment. We showed that HIF-1α overexpression per se was sufficient to up-regulate FN in both cell lines as demonstrated by the transient transfection of both the constitutively active and wild-type forms of HIF-1α. Our data demonstrate the involvement of the PI3K/Akt/HIF-1 pathway in mediating T3 induced FN up-regulation.

Three-dimensional culture of a genetically modified hepatoma cell line using macroporous gelatin beads

Hepatoma cells are a candidate cell source for bio-artificial livers. However, they exhibit reduced liver functions compared with primary hepatocytes. In our previous study, genetically engineered mouse hepatoma cells were created by transduction with vectors mediating inducible overexpression of eight liver-enriched transcription factors. Upon the induction of the liver-enriched transcription factors transduced, the cells expressed both phenotypic and genotypic liver functions at high levels. In the present study, we performed three-dimensional culture of these cells using macroporous gelatin beads. When immobilized on the macroporous gelatin beads, these cells exhibited further enhancement in liver functionality, including increased albumin secretion, ammonia removal and cytochrome P450 activity. The levels of these functions were significantly enhanced compared to monolayer culture. The method is simple and scalable, and provides highly functional cells that can be used in basic and applied fields of hepatic research.

INHIBITORY EFFECT OF CHITOSAN OLIGOSACCHARIDE ON HUMAN HEPATOMA CELLS IN VITRO

Background:

Chitosan oligosaccharide, the degradation products of chitin, was reported to have a wide range of physiological functions and biological activities. In this study, we explored the inhibitory effect of Chitosan oligosaccharide on human hepatoma cells

Materials and Methods:

MTT assay was applied to detect cell viability of the human hepatoma cells treated with Chitosan oligosaccharide. Flow cytometric analysis was used to investigate the apoptosis of the human hepatoma cells treated with Chitosan oligosaccharide. We employed western blot to investigate the underlying mechanisms involved in the apoptosis.

Results:

Our data indicated that chitosan oligosaccharide dose-dependently inhibited the growth of hepatoma cells and induced apoptosis. On the molecular level, chitosan oligosaccharide decreased Bcl-2 and increased Caspase-3 expression which may be related to the apoptosis of hepatoma cells.

Conclusion:

Our results provide an experimental basis for the clinical development of Chitosan oligosaccharide as a novel anti-hepatoma drug.

Establishment of MicroRNA delivery system by PP7 bacteriophage-like particles carrying cell-penetrating peptide

MicroRNAs have great therapeutic potential in cancer and other diseases. However, their instability and low in vivo delivery efficiency limits their application. Recombinant PP7 bacteriophage-based virus-like particles (VLPs) could protect microRNAs against rapid degradation by RNase by packaging specific exogenous pre-microRNAs using the pac site. Insertion of a cell-penetrating peptide (CPP) into the AB-loop of VLPs could significantly improve the delivery efficiency of microRNAs into mammalian cells. Unlike other microRNA delivery methods (viral or non-viral vectors), recombinant PP7 VLPs carrying a CPP and microRNA could be efficiently expressed in Escherichia coli using the one-plasmid double expression system. Here we showed that PP7 VLPs carrying a CPP penetrated hepatoma SK-HEP-1 cells and delivered the pre-microRNA-23b, which was processed into a mature product within 24 h; a concentration of 10 nM was sufficient for the inhibition of hepatoma cell migration via the downregulation of liver-intestine cadherin expression. Furthermore, PP7 VLPs carrying a CPP and a pre-microRNA were not infectious, replicative, or cytotoxic. Therefore, recombinant PP7 VLPs can be used for simultaneous and targeted delivery of both microRNAs and peptides because of their ability to package specific exogenous RNA using the pac site and to display peptides.

Influence of oxygen partial pressure on the characteristics of human hepatocarcinoma cells

Most of the in vitro studies using liver cell lines have been performed under atmospheric oxygen partial pressure (21% O₂). However, the oxygen concentrations in the liver and cancer cells are far from this value. In the present study, we have evaluated the influence of oxygen on 1) the tumor cell lines features (growth, steady-state ROS levels, GSH content, activities of antioxidant enzymes, p66 Shc and SOD expressions, metalloproteinases secretion, migration, invasion, and adhesion) of human hepatocellular carcinoma cell lines, and b) the response of the cells to an oxidant stimulus (aqueous leaf extract of the V. baccifera plant species). For this purpose, three hepatocarcinoma cell lines with different p53 status, HepG2 (wild-type), Huh7 (mutated), and Hep3B (deleted), were cultured (6–30 days) under atmospheric (21%) and more physiological (8%) pO₂. Results showed that after long-term culturing at 8% versus 21% O₂, the cellular proliferation rate and the steady-state levels of mitochondrial O₂^- were unaffected. However, the intracellular basal ROS levels were higher independently of the characteristics of the cell line. Moreover, the lower pO₂ was associated with lower glutathione content, the induction of p66 Shc and Mn-SOD proteins, and increased SOD activity only in HepG2. This cell line also showed a higher migration rate, secretion of active metalloproteinases, and a faster invasion. HepG2 cells were more resistant to the oxidative stress induced by V. baccifera. Results suggest that the long-term culturing of human hepatoma cells at a low, more physiological pO₂ induces antioxidant adaptations that could be mediated by p53, and may alter the cellular response to a subsequent oxidant challenge. Data support the necessity of validating outcomes from studies performed with hepatoma cell cultures under ambient O₂.

•

The influence of pO₂ on human hepatocellular carcinoma cell features is analyzed.

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Low oxygen tension (8% O₂) induces antioxidant adaptations in HepG2.

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Low O₂ increases the migration and invasion rates of HepG2.

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Antioxidant adaptations could be p53-dependent.

•

Validating results from in vitro studies using cells cultured at 21% O₂ are required.

Expression and bioactivity of human α-fetoprotein in a Bac-to-Bac system

α-fetoprotein (AFP) is an early serum growth factor in foetal embryonic development and hepatic oncogenesis. A growing number of investigations of AFP as a tumour-specific biomarker have concluded that AFP is an important target for cancer treatment. AFP also plays an immunomodulatory role in the treatment of several autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis, myasthenia gravis and thyroiditis. In an effort to support biochemical screening and drug design and discovery, we attempted to express and purify human AFP in a Bac-to-Bac system. Two key factors affecting the expression of recombinant human AFP (R-AFP), namely the infectious baculovirus inoculum volume and the culturing time post-infection, were optimized to maximize the yield. We achieved a high yield of approximately 1.5 mg/l of harvested medium with a 72–96 h incubation period after infection and an inoculum volume ratio of 1:100. We also assessed the role of R-AFP in the proliferation of the human liver cancer cell line Bel 7402, and the results indicated that R-AFP promoted the growth of hepatoma cells. We concluded that this method can produce high yields of R-AFP, which can be used for studies related to AFP.

Epimeric spirolactone-type triterpenoids from Abies faxoniana Rehd

Phytochemical investigation of Abies faxoniana Rehd. led to the isolation of two pairs of new epimeric spirolactone-type triterpenoids (1/1' and 2/2') and 11 known terpenoids (3-13). Compounds 1/1' and 2/2' were isolated as epimeric mixtures due to the C-23 ketal tautomerism in their spirolactone structures. The dynamic HPLC manifested that the C-23 epimeric mixtures interconverted into each other in solution. Structure determinations were based on extensive NMR and HRESIMS spectroscopic analysis. Meanwhile, their cytotoxic activities were tested by MTT method. Compound 5 showed cytotoxicities against MCF-7 and A549 cells with IC50 values of 6.5 and 5.7μM, respectively. Compounds 1/1' had IC50 values of 10.0 and 12.3μM for Huh7 and SMMC7721 cells, respectively.

MicroRNA-505 suppresses proliferation and invasion in hepatoma cells by directly targeting high-mobility group box 1

AIMS

MicroRNA-505 (miR-505) expressions have been reported to be altered in the serum of HCC patients. However, the effect and underlying mechanism of miR-505 in hepatoma cells remains poorly understood. The present study intended to investigate the expression levels and the probable role and molecular basis of miR-505 in hepatoma cells.

MAIN METHODS

Real-time PCR was used to determine the miR-505 expressions in hepatoma cell lines QGY-7703, SMMC-7721 and MHCC97. Furthermore, an up-or down-regulation of miR-505 was performed in MHCC97 by transfected with miR-505 mimics or anti-miR-505, respectively. Cell proliferation, cell invasion, and epithelial-mesenchymal transition were determined. Moreover, the target gene of miR-505 was also investigated.

KEY FINDINGS

The expressions of miR-505 were down-regulated in three hepatoma cell lines. MHCC97 possessed the lowest miR-505 levels among the three hepatoma cell lines. Furthermore, the up-regulation of miR-505 suppressed, whereas the down-regulation of miR-505 promoted proliferation, invasion and epithelial-mesenchymal transition in MHCC97. Moreover, miR-505 could directly bind to the 3'-untranslated region of High-Mobility Group Box 1. Notably, High-Mobility Group Box 1 knockdown apparently promoted cell proliferation and invasion in MHCC97.

SIGNIFICANCE

We investigated that MiR-505 regulates proliferation and invasion in MHCC97 cells via targeting High-Mobility Group Box 1.

Insulin-like modulation of Akt/FoxO signaling by copper ions is independent of insulin receptor

Copper ions are known to induce insulin-like effects in various cell lines, stimulating the phosphoinositide 3'-kinase (PI3K)/Akt signaling cascade and leading to the phosphorylation of downstream targets, including FoxO transcription factors. The aim of this work was to study the role of insulin- and IGF1-receptors (IR and IGF1R) in insulin-like signaling induced by copper in HepG2 human hepatoma cells. Cells were exposed to Cu(II) at various concentrations for up to 60 min. While Akt and FoxO1a/FoxO3a were strongly phosphorylated in copper- and insulin-treated cells at all time points studied, only faint tyrosine phosphorylation of IR/IGF1R was detected in cells exposed to Cu(II) by either immunoprecipitation/immunoblot or by immunoblotting using phospho-specific antibodies, whereas insulin triggered strong phosphorylation at these sites. Pharmacological inhibition of IR/IGF1R modestly attenuated Cu-induced Akt and FoxO phosphorylation, whereas no attenuation of Cu-induced Akt activation was achieved by siRNA-mediated IR depletion. Cu(II)-induced FoxO1a nuclear exclusion was only slightly impaired by pharmacological inhibition of IR/IGF1R, whereas insulin-induced effects were blunted. In contrast, genistein, a broad-spectrum tyrosine kinase inhibitor, at concentrations not affecting IR/IGF1R, attenuated Cu(II)-induced Akt phosphorylation, pointing to the requirement of tyrosine kinases other than IR/IGF1R for Cu(II)-induced signaling.

Correlation between GPC3 expression and proliferation of hepatocellular carcinoma cells

AIM: To investigate the relationship between GPC3 expression and proliferative ability of hepatocellular carcinoma (HCC) cells.

METHODS: Immunohistochemistry was employed to detect the expression of GPC3 in 54 HCC tissues. The correlation between GPC3 expression and Ki-67 labeling index and other clinicopathologic characteristics was studied. An shRNA targeting the GPC3 gene was transfected into SMMC7721 cells to silence GPC3 expression. MTT assay was performed to determine the effect of GPC3 knockdown on the growth of HCC SMMC7721 cells.

RESULTS: GPC3 expression was significantly correlated with Ki-67 Li (r = 0.521, P = 0.000). GPC3 expression was related to differentiation degree and vessel invasion of HCC (r = 0.287, 0.289; P = 0.035, 0.034). The cell proliferative activity was significantly reduced in the GPC3-shRNA group compared with the negative control group and blank control group (F = 45.38, P = 0.000).

CONCLUSION: GPC3 may play an important role in the occurrence, development and invasion of HCC, mainly due to the effect on the proliferation of HCC cells.

Hydrogen sulfide (H2S)/cystathionine γ-lyase (CSE) pathway contributes to the proliferation of hepatoma cells

Hydrogen sulfide (H2S)/cystathionine γ-lyase (CSE) pathway has been demonstrated to play vital roles in physiology and pathophysiology. However, its role in tumor cell proliferation remains largely unclear. Here we found that CSE over-expressed in hepatoma HepG2 and PLC/PRF/5 cells. Inhibition of endogenous H2S/CSE pathway drastically decreased the proliferation of HepG2 and PLC/PRF/5 cells, and it also enhanced ROS production and mitochondrial disruption, pronounced DNA damage and increased apoptosis. Moreover, this increase of apoptosis was associated with the activation of p53 and p21 accompanied by a decreased ratio of Bcl-2/Bax and up-regulation of phosphorylated c-Jun N-terminal kinase (JNK) and caspase-3 activity. In addition, the negative regulation of cell proliferation by inhibition of H2S/CSE system correlated with the blockage of cell mitogenic and survival signal transduction of epidermal growth factor receptor (EGFR) via down-regulating the extracellular-signal-regulated kinase 1/2 (ERK1/2) activation. These results demonstrate that H2S/CSE and its downstream pathway contribute to the proliferation of hepatoma cells, and inhibition of this pathway strongly suppress the excessive growth of hepatoma cells by stimulating mitochondrial apoptosis and suppressing cell growth signal transduction.