Epigenetic regulation of insulin-like growth factor axis in hepatocellular carcinoma

The m5C/m6A/m7G-related non-apoptotic regulatory cell death genes for the prediction of the prognosis and immune infiltration status in hepatocellular carcinoma

Background

5-methylcytosine/N6-methyladenosine/N7-methylguanosine (m5C/m6A/m7G)-related genes play a critical role in tumor occurrence and progression, and non-apoptotic regulatory cell death (NARCD) is closely linked to tumor development and immunity. However, the role of m5C/m6A/m7G-related NARCD genes in hepatocellular carcinoma (HCC) remains unclear. We used m5C/m6A/m7G-related NARCD genes to construct a prognostic model of HCC for prognostic prediction and clinical treatment of patients.

Methods

We obtained transcriptome data for HCC from The Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC). Using the least absolute shrinkage and selection operator (LASSO) regression, we identified m5C/m6A/m7G-related NARCD genes and constructed a prognostic model through multivariate Cox regression. Model performance was assessed using Kaplan-Meier and receiver operating characteristic (ROC) curves, with external validation using the ICGC. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses were used to study differentially expressed genes between high- and low-risk groups. We also examined immune cell infiltration, drug response, and cell communication between tumor cells and immune cells in high-risk groups.

Results

We identified 140 m5C/m6A/m7G-related NARCD genes, using five of them to build the prognostic model. Functional enrichment analysis revealed enrichment in tumor and immune-related pathways for risk genes. The high-risk group displayed increased immune cell infiltration and better responses to immune checkpoint inhibitors (ICIs). High-risk patients were more responsive to cisplatin, doxorubicin, and mitomycin C, while low-risk patients were more sensitive to erlotinib. Cell communication analysis indicated that high-risk tumor cells used insulin-like growth factor (IGF) and macrophage migration inhibitory factor (MIF) signaling pathways to send signals to immune cells and received signals through the bone morphogenetic protein (BMP) and lymphotoxin-related inducible ligand (LIGHT) pathways.

Conclusions

We have developed a prognostic model with m5C/m6A/m7G-related NARCD genes to predict the prognosis of HCC patients. This model can offer insights into the effectiveness of immunotherapy and chemotherapy for HCC patients.

The regulation of proliferation and apoptosis in hepatocellular carcinoma via insulin-like growth factor 1 receptor

OBJECTIVES

Insulin-like growth factor 1 receptor (IGF-1R) is a transmembrane tyrosine kinase receptor of the insulin receptor family. Its expression is consistently increased in hepatocellular carcinoma (HCC) tissue, and it participates in hepatic carcinogenesis. Targeting IGF-1R may be a potential therapeutic approach against hepatocellular carcinoma. This study therefore aimed to explore the effect of IGF-1R on hepatocellular carcinoma cells.

METHODS

IGF-1R silencing cell lines were established by small-interfering RNAs in hepatocellular carcinoma cell line SMMC7721, after which the proliferation, invasion, and apoptosis of SMMC7721 was evaluated. The activation of the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway and the expression of bone morphogenetic protein (BMP)-2 and BMP-7 were measured using Western blot analysis.

RESULTS

The results indicated that the knockdown of IGF-1R can inhibit the proliferation and invasion of HCC and promote the apoptosis of SMMC7721 by inhibiting the PI3K/AKT signaling pathway. Furthermore, depletion of IGF-1R was found to suppress the expression of BMP-2 and BMP-7.

CONCLUSIONS

The findings suggest that IGF-1R plays an important role in the progression of HCC. Therefore, IGF-1R is a potential target for the treatment of HCC in clinic.

The role of YAP1 in liver cancer stem cells: proven and potential mechanisms

YAP1 (Yes-associated protein 1) is one of the principal factors that mediates oncogenesis by acting as a driver of gene expression. It has been confirmed to play an important role in organ volume control, stem cell function, tissue regeneration, tumorigenesis and tumor metastasis. Recent research findings show that YAP1 is correlated with the stemness of liver cancer stem cells, and liver cancer stem cells are closely associated with YAP1-induced tumor initiation and progression. This article reviews the advancements made in research on the mechanisms by which YAP1 promotes liver cancer stem cells and discusses some potential mechanisms that require further study.

The Role of MicroRNAs in Influencing Body Growth and Development

Body growth and development are regulated among others by genetic and epigenetic factors. MicroRNAs (miRNAs) are epigenetic regulators of gene expression that act at the post-transcriptional level, thereby exerting a strong influence on regulatory gene networks. Increasing studies suggest the importance of miRNAs in the regulation of the growth plate and growth hormone (GH)-insulin-like growth factor (IGF) axis during the life course in a broad spectrum of animal species, contributing to longitudinal growth. This review summarizes the role of miRNAs in regulating growth in different in vitro and in vivo models acting on GH, GH receptor (GHR), IGFs, and IGF1R genes besides current knowledge in humans, and highlights that this regulatory system is of importance for growth.

Value of KPNA4 as a diagnostic and prognostic biomarker for hepatocellular carcinoma

It is important to identify novel biomarkers to improve hepatocellular carcinoma (HCC) diagnosis and treatment. Herein, we reported the role of karyopherin α4 (KPNA4) in HCC patients through public data mining and examined the results using clinical samples in our center. Our results revealed that KPNA4 expression level was positively correlated with the infiltration of CD8⁺ T cells, B cells, dendritic cells, CD4⁺ T cells, neutrophils and macrophages. In addition, KPNA4 expression was significantly associated with T cell exhaustion. KPNA4 mRNA and protein expression levels were significantly higher in cancerous tissue than in normal tissue. Besides, the increased expression of KPNA4 indicated poor overall survival. Univariate and multivariate Cox regression analyses showed KPNA4 could be viewed as an independent risk factor for HCC patients. Moreover, our experimental results were consistent with those obtained from bioinformatic results. These findings revealed KPNA4 may serve as a novel prognostic biomarker and a potential therapeutic target for HCC.

Role of exosomes in pathogenesis, progression, diagnosis and treatment of hepatocellular carcinoma

Exosomes are nanovesicles that may play a role in intercellular communication by acting as carriers of functional contents such as proteins, lipids, RNA molecules, and circulating DNA between cells. In addition, exosomes may play a potential role in immunosurveillance and tumor pathogenesis and progression. Recently, research has increasingly focused on the role of exosomes in hepatocellular carcinoma (HCC), the most common primary liver malignancy. In addition to their diagnostic value in HCC, exosomes are also involved in different mechanisms of HCC pathogenesis and progression including angiogenesis and immune escape. Moreover, exosomes have been demonstrated to change the tumor microenvironment to a less tolerogenic state, favoring immune response and tumor suppression. These results underline a practical and potentially feasible role of exosomes in the treatment of patients with HCC, both as a target and a vehicle for drug design. Future studies need to further elucidate the exact role and reliability of exosomes as screening, diagnosis, and treatment targets in patients with HCC. We herein review the data on emerging experimental and clinical studies that focused on the role of exosomes in the pathogenesis, progression, diagnosis, and therapy response of patients with HCC.

Metformin Counteracts HCC Progression and Metastasis Enhancing KLF6/p21 Expression and Downregulating the IGF Axis

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is the common tumor of the liver. Unfortunately, most HCC seem to be resistant to conventional chemotherapy and radiotherapy. The poor efficacy of antitumor agents is also due, at least in part, to the inefficient drug delivery and metabolism exerted by the steatotic/cirrhotic liver that hosts the tumor. Thus, novel approaches in chemotherapy may be needed to improve the survival rate in patients with HCC. Metformin (METF) has been found to lower HCC risk; however, the mechanisms by which METF performs its anticancer activity are not completely elucidated. Previous studies have showed METF action on growth inhibition in the liver in a dose/time-dependent manner and its antitumor role by targeting multiple pathways. We investigated molecular effects of METF in an in vitro human hepatoma model (HepG2), studying cell cycle regulators, tumorigenesis markers, and insulin-like growth factor (IGF) axis regulation.

MATERIALS AND METHODS

HepG2 cells were treated with METF (400 μM) for 24, 48, and 72 hours. METF action on cell cycle progression and cellular pathways involved in metabolism regulation was evaluated by gene expression analysis, immunofluorescence, and Western blot assay.

RESULTS

By assessing HepG2 cell viability, METF significantly decreased growth cell capacity raising KLF6/p21 protein content. Moreover, METF ameliorated the cancer microenvironment reducing cellular lipid drop accumulation and promoting AMPK activity. The overexpression of IGF-II molecule and the IGF-I receptor that plays a main role in HCC progression was counteracted by METF. Furthermore, the protein content of HCC principal tumor markers, CK19 and OPN, linked to the metastasis process was significantly reduced by METF stimulus.

CONCLUSION

Our data show that METF could suppress HepG2 proliferation, through induction of cell cycle arrest at the G0/G1 phase. In addition, METF effect on the cancer microenvironment and on the IGF axis leads to the development of new METF therapeutic use in HCC treatment.

Folic Acid Reduced Triglycerides Deposition in Primary Chicken Hepatocytes

Abdominal fat or fatty liver cause huge economic losses in the poultry industry, and nonalcoholic fatty liver disease (NAFLD) is also a global health issue in humans. More than 90% of de novo lipogenesis in humans and chickens is undertaken by the liver, which is proved to be full of lipids in new-born chickens. Folic acid was thought to have correlation with lipid metabolism. Primary hepatocytes from new-born chickens were employed as a natural model of early stage fatty liver in vitro and further to explore whether folic acid could prevent fatty liver in the current study. We found that folic acid addition reduced triglyceride deposition by suppressing de novo fatty acid synthesis and coordinately promoting triglyceride hydrolysis and exportation in primary chicken hepatocytes from new-born chickens. In addition, lipogenesis suppression was through the PI3K/AKT/SREBP pathway mediated by weakening insulin/IGF signal. Our data suggested that folic acid may be considered as a precautionary strategy for abdominal fat deposition in broilers or fatty liver in laying hens and humans. In addition, mechanism regulation also implied that an IGF2 inhibitor and PI3K inhibitor may be used for the NAFLD precautionary measure to reduce TG deposition.

Diabetes and hepatocellular carcinoma: A pathophysiological link and pharmacological management

Both diabetes mellitus (DM) and cancer are multifarious, dissimilar, and long-lasting, fatal diseases with a remarkable influence on health worldwide. DM is not only related to cardiovascular diseases, neuropathy, nephropathy, and retinopathy, but also related to a number of liver diseases such as nonalcoholic fatty liver disease, steatohepatitis, and liver cirrhosis. Recently, it is hypothesized that DM has a greater risk for many forms of cancer, such as breast, colorectal, endometrial, pancreatic, gallbladder, renal, and liver cancer including hepatocellular carcinoma (HCC). Both DM and cancer have many common risk factors, but the association between these two is poorly stated. Several epidemiologic studies have revealed the association between pathogenic and prognostic characteristics of DM and a higher incidence of HCC, thus representing DM as an independent risk factor for HCC development. The etiological and pathophysiological relationship between DM and HCC has been presented in this review by linking hyperglycemia, hyperinsulinemia, insulin resistance, and activation of insulin-like growth factor signaling pathways and pharmacological management of HCC associated with DM.

LncRNA CASC2 inhibited the viability and induced the apoptosis of hepatocellular carcinoma cells through regulating miR-24-3p

Cancer susceptibility candidate 2 (CASC2), a recently discovered long non-coding RNA (lncRNA), was confirmed to play numerous roles in several human cancers. However, the involvement and concrete mechanism of CASC2 in hepatocellular carcinoma (HCC) still need to be further elucidated. The relative expressions of CASC2 and miR-24-3p in HCC tissue and cell lines were determined by quantitative real-time PCR (qRT-PCR). The effects of CASC2 and miR-24-3p on HCC cells were further assessed via cell viability and apoptosis. In vivo tumorigenesis assay was performed to verify the inhibition effect of CASC2 on the tumor growth and further clarify the important role of miR-24-3p in this mechanism. Compared with the paired normal tissues, the relative expression of CASC2 significantly reduced in the HCC tissues, while miR-24-3p as determined by qRT-PCR obviously increased in the HCC tissues. This observation was also found in HCC cell lines. Meanwhile, the expression of CASC2 was negatively related to miR-24-3p expression in the HCC tissues (r = -0.804, P < 0.001). CASC2 could negatively regulate the expression of miR-24-3p in vitro. Moreover, CASC2 overexpression resulted in the growth inhibitory and apoptosis-inducing effects on HCC cells, but the up-regulation of miR-24-3p greatly eliminated the CASC2-induced effects. The tumorigenesis of HCC cells was restrained significantly by CASC2 overexpression as shown by decreased tumor volume and growth rate. However, miR-24-3p up-regulation rescued the inhibition of CASC2 on the tumor growth in tumor-bearing mice. LncRNA CASC2 inhibited the viability and induced the apoptosis of HCC cells through regulating miR-24-3p.

RNA-binding protein AUF1 suppresses miR-122 biogenesis by down-regulating Dicer1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the common cancers worldwide, especially in developing countries. Although the chronic infections of hepatitis B and C viruses have been established as the etiological factors of HCC, the mechanism for the tumorigenesis and development of HCC is still unclear. The liver-specific microRNA-122 (miR-122), an established tumor-suppressor miRNA, is often down-regulated in HCC, while the underlying mechanism is not well understood. Here we report that the AU-rich element-binding factor AUF1 suppresses the expression of Dicer1, the type III RNase that is required for microRNA maturation, leading to the inhibited biogenesis of miR-122. Overexpression of AUF1 led to the decreased expression of Dicer1 and miR-122, while the level of the miR-122 precursor (pre-miR-122) was increased. On the other hand, siRNA of AUF1 (siAUF1) increased the levels of Dicer1 mRNA and miR-122, but it reduced the abundance of pre-miR-122. Consistent with the reported data, this study demonstrated that AUF1 and Dicer1 showed opposite expression pattern in both human HCC tissues and cell lines. In addition, AUF1 inhibited the expression of Dicer1 by interacting with the 3′ untranslated region (3′UTR) and coding region of DICER1 mRNA. Moreover, the knockdown of AUF1 by siRNA altered the expression of other miRNAs and promoted HCC cell death. In conclusion, AUF1 down-regulates the expression miR-122 by interacting with the 3′UTR and coding region of DICER1 mRNA and suppressing Dicer1 expression. The AUF1/Dicer1/miR-122 pathway might play a critical role in the development of HCC.