MicroRNA-374a Promotes Hepatocellular Carcinoma Cell Proliferation by Targeting Mitogen-Inducible Gene 6 (MIG-6)

Prognostic MicroRNA Fingerprints Predict Recurrence of Early-Stage Hepatocellular Carcinoma Following Hepatectomy

Purpose: This study aims to develop liquid biopsy assays for early HCC diagnosis and prognosis. Methods: Twenty-three microRNAs were first consolidated as a panel (HCCseek-23 panel) based on their reported functions in HCC development. Serum samples were collected from 103 early-stage HCC patients before and after hepatectomy. Quantitative PCR and machine learning random forest models were applied to develop diagnostic and prognostic models. Results: For HCC diagnosis, HCCseek-23 panel demonstrated 81% sensitivity and 83% specificity for identifying HCC in the early-stage; it showed 93% sensitivity for identifying alpha-fetoprotein (AFP)-negative HCC. For HCC prognosis, the differential expressions of 8 microRNAs (HCCseek-8 panel: miR-145, miR-148a, miR-150, miR-221, miR-223, miR-23a, miR-374a, and miR-424) were significantly associated with disease-free survival (DFS) (Log-rank test p-value = 0.001). Further model improvement using these HCCseek-8 panel in combination with serum biomarkers (i.e. AFP, ALT, and AST) demonstrated a significant association with DFS (Log-rank p-value = 0.011 and Cox proportional hazards analyses p-value = 0.002). Conclusion: To the best of our knowledge, this is the first report to integrate circulating miRNAs, AST, ALT, AFP, and machine learning for predicting DFS in early HCC patients undergoing hepatectomy. In this setting, HCCSeek-23 panel is a promising circulating microRNA assay for diagnosis, while HCCSeek-8 panel is promising for prognosis to identify early HCC recurrence.

Hypermethylation of Mig-6 gene promoter region inactivates its function, leading to EGFR/ERK signaling hyperphosphorylation, and is involved in arsenite-induced hepatic stellate cells activation and extracellular matrix deposition

Arsenic is a widespread naturally contaminant. Previous studies have highlighted the issue of liver fibrosis induced by arsenic exposure, while the exact mechanisms are not yet fully understood. Recent studies suggest that Mig-6/EGFR/ERK signaling appear to play important roles in fibrosis caused by various factors. In this study, we focused on the epigenetic modification combined with the signaling dysregulation to validate the role of Mig-6 in regulating EGFR/ERK signaling in arsenite-induced human hepatic stellate cells (HSCs) activation. Our results revealed that arsenite exposure induced HSCs activation and extracellular matrix (ECM) deposition. The EGFR/ERK signaling was significantly hyperphosphorylated in arsenite-exposed HSCs, and Mig-6 inactivation was involved in arsenite induced hyperphosphorylation of EGFR and activation of HSCs. Additionally, we further illustrated that hypermethylation of Mig-6 gene promoter region was responsible for the downregulation of Mig-6 induced by arsenite exposure. Moreover, 5-Aza-dC (a DNA methyltransferase inhibitor) can efficiently rescue hypermethylation of Mig-6 gene, decrease the hyperphosphorylation of EGFR/ERK signaling, then reverse arsenite induced HSCs activation. Taken together, the present study strongly suggests that inactivating of Mig-6 function by hypermethylation of its promoter region leading to hyperphosphorylation of EGFR/ERK signaling, and is involved in arsenite-induced HSCs activation and ECM deposition.

Mig-6 Inhibits Autophagy in HCC Cell Lines by Modulating miR-193a-3p

Mitogen-inducible gene 6 (Mig-6) is a tumor suppressor gene that plays an important role in many types of cancers by interacting with EGFR. However, its molecular mechanism in hepatocellular carcinoma (HCC) and its relationship with miRNAs need to be elucidated. Therefore, this study aimed to explore whether Mig-6 could promote apoptosis and the inhibition of autophagy via its downstream miRNA in HCC cell lines. We used two cell lines, HepG2 and HLE, to establish Mig-6 overexpression and knockdown experiments, as well as miR-193a mimic and inhibitor experiments. The miRNA microarray profiling was also used to verify Mig-6-regulated miRNA. We found that Mig-6 induced apoptosis and reduced autophagy of HCC cell lines. miR-193a-3p is a Mig-6-regulated miRNA in the Mig-6-overexpression model. It affected the apoptosis and autophagy of HCC cells, at least partly by regulating the expression of TGF-β2. Additionally, the relationship between Mig-6 and transforming growth factor TGF-β2 was explored in depth for the first time. These findings revealed an important role of Mig-6 in the apoptosis and autophagy of HCC cells by regulating miR-193a-3p, providing a novel insight into the therapeutic target in HCC.

Mig-6 could inhibit cell proliferation and induce apoptosis in esophageal squamous cell carcinoma

BACKGROUND

To investigate the expression and biological functions of mitogen-induced gene 6 (Mig-6) in esophageal squamous cell carcinoma (ESCC).

METHODS

The expression of Mig-6 in ESCC tissues and normal esophageal epithelial tissues were measured by immunohistochemistry (IHC) assay. MTT test was applied to detect the proliferative ability of ESCC cells after Mig-6 was upregulated by transfection. A fluid cytology assay was used to detect apoptosis of ESCC cells. Agilent whole human genome oligo microarray was used to screen different expressed genes and the possible signaling pathways which might be involved.

RESULTS

The expression of Mig-6 protein was lower in ESCC tissues compared to normal esophageal epithelial tissues. Mig-6 could restrain the ESCC cell growth and induce cell apoptosis. PPAR, CAMs and MAPK signaling pathways might be involved.

CONCLUSIONS

Mig-6 might be a new tumor suppressor gene and a possible target for the specific therapy of ESCC.

Gene 33/Mig6/ERRFI1, an Adapter Protein with Complex Functions in Cell Biology and Human Diseases

Gene 33 (also named Mig6, RALT, and ERRFI1) is an adapter/scaffold protein with a calculated molecular weight of about 50 kD. It contains multiple domains known to mediate protein–protein interaction, suggesting that it has the potential to interact with many cellular partners and have multiple cellular functions. The research over the last two decades has confirmed that it indeed regulates multiple cell signaling pathways and is involved in many pathophysiological processes. Gene 33 has long been viewed as an exclusively cytosolic protein. However, recent evidence suggests that it also has nuclear and chromatin-associated functions. These new findings highlight a significantly broader functional spectrum of this protein. In this review, we will discuss the function and regulation of Gene 33, as well as its association with human pathophysiological conditions in light of the recent research progress on this protein.

Honokiol Prevents Non-Alcoholic Steatohepatitis-Induced Liver Cancer via EGFR Degradation through the Glucocorticoid Receptor-MIG6 Axis

Non-alcoholic steatohepatitis (NASH) has become a serious public health problem associated with metabolic syndrome. The mechanisms by which NASH induces hepatocellular carcinoma (HCC) remain unknown. There are no approved drugs for treating NASH or preventing NASH-induced HCC. We used a genetic mouse model in which HCC was induced via high-fat diet feeding. This mouse model strongly resembles human NASH-induced HCC. The natural product honokiol (HNK) was tested for its preventative effects against NASH progression to HCC. Then, to clarify the mechanisms underlying HCC development, human HCC cells were treated with HNK. Human clinical specimens were also analyzed to explore this study's clinical relevance. We found that epidermal growth factor receptor (EGFR) signaling was hyperactivated in the livers of mice with NASH and human HCC specimens. Inhibition of EGFR signaling by HNK drastically attenuated HCC development in the mouse model. Mechanistically, HNK accelerated the nuclear translocation of glucocorticoid receptor (GR) and promoted mitogen-inducible gene 6 (MIG6)/ERBB receptor feedback inhibitor 1 (ERRFI1) expression, leading to EGFR degradation and thereby resulting in robust tumor suppression. In human samples, EGFR-positive HCC tissues and their corresponding non-tumor tissues exhibited decreased ERRFI1 mRNA expression. Additionally, GR-positive non-tumor liver tissues displayed lower EGFR expression. Livers from patients with advanced NASH exhibited decreased ERRFI1 expression. EGFR degradation or inactivation represents a novel approach for NASH-HCC treatment and prevention, and the GR-MIG6 axis is a newly defined target that can be activated by HNK and related compounds.

Exosome-mediated miRNA delivery promotes liver cancer EMT and metastasis

The deregulation of exosomal microRNAs (miRNAs) plays an important role in the progression of hepatocarcinogenesis. In this study, we highlight exosomes as mediators involved in modulating miRNA profiles in liver cancer cells after induction of the epithelial-mesenchymal transition (EMT) and metastasis. Initially, we induced EMT in a hepatocellular carcinoma cell (HCC) line (Hep3B) by stimulation with transforming growth factor-β (TGF-β) and confirmed by western blot detection of EMT markers such as vimentin and E-cadherin. Exosomes were then isolated from the cells and identified by nanoparticle tracking analysis (NTA). The isolated exosomal particles from unstimulated Hep3B cells (Hep3B exo) or TGF-β-stimulated EMT Hep3B cells (EMT-Hep3B exo) contained higher levels of exosome marker proteins, CD63 and TSG101. After incubation with EMT-Hep3B exo, Hep3B cell proliferation increased. EMT-Hep3B exo promoted the migration and invasion of Hep3B and 7721 cells. High-throughput sequencing of miRNAs and mRNA within the exosomes showed 119 upregulated and 186 downregulated miRNAs and 156 upregulated and 166 downregulated mRNA sequences in the EMT-Hep3B exo compared with the control Hep3B exo. The most differentially expressed miRNAs and target mRNA sequences were validated by RT-qPCR. Based on the known miRNA targets for specific mRNA sequences, we hypothesized that GADD45A was regulated by miR-374a-5p. Inhibition of miR-374a-5p in Hep3B cells resulted in exosomes that inhibited the proliferation, migration, and invasion of HCC cells. These results enhance our understanding of metastatic progression of liver cancer and provide a foundation for the future development of potential biomarkers for diagnosis and prognosis of hepatic cancer.

MicroRNA-374a Expression as a Prognostic Biomarker in Lung Adenocarcinoma

BACKGROUND

Lung cancer is the most common cause of cancer-related death, and adenocarcinoma is the most common histologic subtype. MicroRNA is a small non-coding RNA that inhibits multiple target gene expression at the post-transcriptional level and is commonly dysregulated in malignant tumors. The purpose of this study was to analyze the expression of microRNA-374a (miR-374a) in lung adenocarcinoma and correlate its expression with various clinicopathological characteristics.

METHODS

The expression level of miR-374a was measured in 111 formalin-fixed paraffin-embedded lung adenocarcinoma tissues using reverse transcription-quantitative polymerase chain reaction assays. The correlation between miR-374a expression and clinicopathological parameters, including clinical outcome, was further analyzed.

RESULTS

High miR-374 expression was correlated with advanced pT category (chi-square test, p=.004) and pleural invasion (chi-square test, p=.034). Survival analysis revealed that patients with high miR-374a expression had significantly shorter disease-free survival relative to those with low miR-374a expression (log-rank test, p=.032).

CONCLUSIONS

miR-374a expression may serve as a potential prognostic biomarker for predicting recurrence in early stage lung adenocarcinoma after curative surgery.

Modulation of the IL-6-Signaling Pathway in Liver Cells by miRNAs Targeting gp130, JAK1, and/or STAT3

Interleukin-6 (IL-6)-type cytokines share the common receptor glycoprotein 130 (gp130), which activates a signaling cascade involving Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) transcription factors. IL-6 and/or its signaling pathway is often deregulated in diseases, such as chronic liver diseases and cancer. Thus, the identification of compounds inhibiting this pathway is of interest for future targeted therapies. We established novel cellular screening systems based on a STAT-responsive reporter gene (Cypridina luciferase). Of a library containing 538 microRNA (miRNA) mimics, several miRNAs affected hyper-IL-6-induced luciferase activities. When focusing on candidate miRNAs specifically targeting 3′ UTRs of signaling molecules of this pathway, we identified, e.g., miR-3677-5p as a novel miRNA affecting protein expression of both STAT3 and JAK1, whereas miR-16-1-3p, miR-4473, and miR-520f-3p reduced gp130 surface expression. Interestingly, combination treatment with 2 or 3 miRNAs targeting gp130 or different signaling molecules of the pathway did not increase the inhibitory effects on phospho-STAT3 levels and STAT3 target gene expression compared to treatment with single mimics. Taken together, we identified a set of miRNAs of potential therapeutic value for cancer and inflammatory diseases, which directly target the expression of molecules within the IL-6-signaling pathway and can dampen inflammatory signal transduction.

The role and mechanism of miR-374 regulating the malignant transformation of mesenchymal stem cells

MicroRNAs (miRNAs) play important roles in cell transformation and carcinogenesis. We have previously established a tumor cell line K3 transformed from rat bone marrow-derived mesenchymal stem cells (rBM-MSCs). However, the underlying mechanism involved in MSC transformation remains unclear. Herein, we identified the key miRNAs that regulate the transformation of rBM-MSCs, and clarified their biological roles. Microarray and qRT-PCR results showed an increased expression of miR-374 but decreased expressions of miR-199a, miR-145, miR-34a, and miR-214 in K3 cells compared to rBM-MSCs. MiR-374 overexpression in rBM-MSCs increased the colony number and the proportion of the cells in S-phase. In addition, miR-374 overexpression reduced E-cadherin expression and increased N-cadherin expression in rBM-MSCs, promoting the migration ability of these cells. On the contrary, miR-374 knockdown in K3 cells led to impaired proliferation and migration capacities. Furthermore, wnt5a was identified as a target gene of miR-374. MiR-374 overexpression upregulated β-catenin expression in rBM-MSCs while miR-374 knockdown downregulated that in K3 cells. In conclusion, miR-374 promotes the proliferation and migration of transformed MSCs by regulating Wnt5a/β-catenin signaling pathway, which provides evidence for the contribution of miRNA to MSC transformation and suggests a new role of miR-374 in cancer development and progression.

miR-33a-5p enhances the sensitivity of lung adenocarcinoma cells to celastrol by regulating mTOR signaling

MicroRNAs (miRNAs or miRs) have recently become a popular focus of cancer research due to their ability to act as oncogenes or tumor suppressors. In the present study, miR‑33a‑5p expression was identified to be downregulated in lung adenocarcinoma samples compared with normal, which suggested that miR‑33a‑5p may serve as a tumor suppressor gene. Transfection with miR‑33a‑5p mimics inhibited the proliferation and migration of A549 and LTEP‑a‑2 cells and increased cellular apoptosis. A luciferase reporter assay confirmed that miR‑33a‑5p targets the 3'‑untranslated region of the mechanistic target of rapamycin (mTOR) gene. mTOR expression was decreased in A549 and LTEP‑a‑2 cells treated with miR‑33a‑5p mimics, as well as the expression of its downstream effectors phosphorylated (p)‑p70 ribosomal protein S6 kinase (p70S6K) and p‑eukaryotic translation initiation factor 4E binding protein 1 (4EBP1). Following treatment with celastrol, miR‑33a‑5p expression was upregulated, and miR‑33a‑5p could enhance cellular sensitivity to celastrol. Western blot analysis revealed that the expression of mTOR, p‑p70S6K and p‑4EBP1 decreased following celastrol treatment. These results suggested that mTOR was involved in the mechanism by which miR‑33a‑5p enhanced the sensitivity of lung adenocarcinoma cells to celastrol. Furthermore, LTEP‑a‑2 cells were xenografted subcutaneously into nude mice, to examine the effect of celastrol and miR‑33a‑5p on the growth of LTEP‑a‑2 cells in vivo. The results demonstrated that tumor growth in the celastrol‑treated or miR‑33a‑5p‑treated group was attenuated compared with the control group. Notably, tumor growth in the combination treatment group was almost arrested after 2 weeks. In addition, celastrol upregulated the expression of miR‑33a‑5p, and high expression of miR‑33a‑5p inhibited mTOR and its downstream effectors. In summary, miR‑33a‑5p inhibited the proliferation of lung adenocarcinoma cells, enhanced the antitumor effect of celastrol, and improved sensitivity to celastrol by targeting mTOR in lung adenocarcinoma in vitro and in vivo.

Protective Effect of miR-374a on Chemical Hypoxia-Induced Damage of PC12 Cells In Vitro via the GADD45α/JNK Signaling Pathway

To explore the effect of microRNA-374a (miR-374a) on chemical hypoxia-induced pheochromocytoma (PC12) cell damage by mediating growth arrest and the DNA damage-45 alpha (GADD45α)/c-Jun N-terminal kinase (JNK) signaling pathway. PC12 cells were divided into a Control group (no treatment), Model group (treated with CoCl₂ for 24 h), negative control (NC) group (transfected with miR-374a negative control sequence and treated with CoCl₂ for 24 h), and miR-374a mimic group (transfected with miR-374a mimics and treated with CoCl₂ for 24 h). The viability and apoptosis of PC12 cells were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, while the mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) content were assessed by Rh123 and dichloro-dihydro-fluorescein diacetate (DCFH-DA) methods. The expression of miR-374a and GADD45α/JNK proteins was detected using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot. A significant decrease was found in the survival rate, MMP and miR-374a expression, while an increase was shown in the ROS content and GADD45α and p-JNK expression in hypoxic PC12 cells (all P < 0.05). A luciferase reporter gene assay demonstrated that GADD45α is the target gene of miR-374a. When transfected with miR-374a mimics, hypoxic PC12 cells showed an obvious elevation in survival rate and MMP but a great reduction in cell apoptosis and ROS content, as well as in the expression of GADD45α and p-JNK proteins (all P < 0.05). MiR-374a can protect PC12 cells against hypoxia-induced injury by inhibiting the GADD45α/JNK pathway, enhancing cell viability, suppressing oxidative stress, and inhibiting cell apoptosis, thereby becoming a potential therapeutic target for hypoxic damage.