The role of AEG-1 in the development of liver cancer

Role of microRNAs in regulation of WNT signaling pathway in urothelial and prostate cancers

Background

Urothelial cancer (UC) and prostate cancer (PCa) are the most common cancers among men with a high ratio of mortality in advanced-stages. The higher risk of these malignancies among men can be associated with higher carcinogens exposure. Molecular pathology of UC and PCa is related to the specific mutations and aberrations in some signaling pathways. WNT signaling is a highly regulated pathway that has a pivotal role during urothelial and prostate development and homeostasis. This pathway also plays a vital role in adult stem cell niches to maintain a balance between stemness and differentiation. Deregulation of the WNT pathway is frequently correlated with tumor progression and metastasis in urothelial and prostate tumors. Therefore, regulatory factors of WNT pathways are being investigated as diagnostic or prognostic markers and novel therapeutic targets during urothelial and prostate tumorigenesis. MicroRNAs (miRNAs) have a pivotal role in WNT signaling regulation in which there are interactions between miRNAs and WNT signaling pathway during tumor progression. Since, the miRNAs are sensitive, specific, and noninvasive, they can be introduced as efficient biomarkers of tumor progression.

Main body

In present review, we have summarized all of the miRNAs that have been involved in regulation of WNT signaling pathway in urothelial and prostate cancers.

Conclusions

It was observed that miRNAs were mainly involved in regulation of WNT signaling in bladder cancer cells through targeting the WNT ligands and cytoplasmic WNT components such as WNT5A, WNT7A, CTNNB1, GSK3β, and AXIN. Whereas, miRNAs were mainly involved in regulation of WNT signaling in prostate tumor cells via targeting the cytoplasmic WNT components and WNT related transcription factors such as CTNNB1, GSK3β, AXIN, TCF7, and LEF1. MiRNAs mainly functioned as tumor suppressors in bladder and prostate cancers through the WNT signaling inhibition. This review paves the way of introducing a noninvasive diagnostic panel of WNT related miRNAs in urothelial and prostate tumors.

The absence of cellular glucose triggers oncogene AEG-1 that instigates VEGFC in HCC: A possible genetic root cause of angiogenesis

BACKGROUND AND OBJECTIVE

Astrocyte Elevated Gene-1 (AEG-1) is the master and multi-regulator of the various transcriptional factor primarily regulating chemoresistance, angiogenesis, metastasis, and invasion under the pathological condition, including liver cancer. This study was focused on investigating the process of tumor angiogenesis in liver carcinoma by studying the role of AEG-1 under GD/2DG conditions.

METHOD AND RESULTS

The PCR and western blot analysis revealed that glucose depletion (GD) induces the overexpression of AEG-1. Further, it leads to the constant expression of VEGFC through the activation of HIF-1α/CCR7 via the stimulations of PI3K/Akt signaling pathways. GLUT2 is the major transporter of a glucose molecule that is highly participating under GD through the expression of AEG-1 and constantly expresses glucokinase (GCK). The obtained data suggest that AEG-1 act as an angiogenesis and glycolysis regulator by modulating the expression of GCK through HIF-1α and GLUT2. 2-deoxy-D-glucose (2DG) is a glycolysis inhibitor that induces impaired glycolysis and cellular apoptosis by cellular oxidative stress. The administration of 2DG has led to the chemoresistance of AEG-1.

CONCLUSION

The total findings of the study judged that disruption of cellular energy metabolism induced by the absence of glucose or the presence of mutant glucose moiety (2DG) promotes the overexpression of AEG-1. The GD/2DG activates the VEGFC by inducing the HIF-1α and CCR7. Moreover, AEG-1 induces the expression of OPN, which regulates metastasis, angiogenesis, and actively participates in protective autophagy by promoting LC3 a/b.

Metadherin (AEG-1/MTDH/LYRIC) expression: Significance in malignancy and crucial role in colorectal cancer

Metadherin (AEG-1/MTDH/LYRIC) is a 582-amino acid transmembrane protein, encoded by a gene located at chromosome 8q22, and distributed throughout the cytoplasm, peri-nuclear region, nucleus, and nucleolus as well as the endoplasmic reticulum (ER). It contains several structural and interacting domains through which it interacts with transcription factors such as nuclear factor-κB (NF-κB), promyelocytic leukemia zinc finger (PLZF), staphylococcal nuclease domain containing 1 (SND1) and lung homing domain (LHD). It is regulated by miRNAs and mediates its oncogenic function via activation of cell proliferation, survival, migration and metastasis, as well as, angiogenesis and chemoresistance via phosphatidylinositol-3-kinase/AKT (PI3K/AKT), NF-κB, mitogen-activated protein kinase (MAPK) and Wnt signaling pathways. In this chapter, metadherin is reviewed highlighting its role in mediating growth, metastasis and chemoresistance in colorectal cancer (CRC). Metadherin, as well as its variants, and antibodies are associated with CRC progression, poorer prognosis, decreased survival and advanced clinico-pathology. The potential of AEG-1/MTDH/LYRIC as a diagnostic and prognostic marker as well as a therapeutic target in CRC is explored.

MicroRNA-96: A therapeutic and diagnostic tumor marker

Cancer has been always considered as one of the main human health challenges worldwide. One of the main causes of cancer-related mortality is late diagnosis in the advanced stages of the disease, which reduces the therapeutic efficiency. Therefore, novel non-invasive diagnostic methods are required for the early detection of tumors and improving the quality of life and survival in cancer patients. MicroRNAs (miRNAs) have pivotal roles in various cellular processes such as cell proliferation, motility, and neoplastic transformation. Since circulating miRNAs have high stability in body fluids, they can be suggested as efficient noninvasive tumor markers. MiR-96 belongs to the miR-183-96-182 cluster that regulates cell migration and tumor progression as an oncogene or tumor suppressor by targeting various genes in solid tumors. In the present review, we have summarized all of the studies that assessed the role of miR-96 during tumor progression. This review clarifies the molecular mechanisms and target genes recruited by miR-96 to regulate tumor progression and metastasis. It was observed that miR-96 mainly affects tumorigenesis by targeting the structural proteins and FOXO transcription factors.

Astrocyte elevated gene-1 (AEG-1): A key driver of hepatocellular carcinoma (HCC)

An array of human cancers, including hepatocellular carcinoma (HCC), overexpress the oncogene Astrocyte elevated gene-1 (AEG-1). It is now firmly established that AEG-1 is a key driver of carcinogenesis, and enhanced expression of AEG-1 is a marker of poor prognosis in cancer patients. In-depth studies have revealed that AEG-1 positively regulates different hallmarks of HCC progression including growth and proliferation, angiogenesis, invasion, migration, metastasis and resistance to therapeutic intervention. By interacting with a plethora of proteins as well as mRNAs, AEG-1 regulates gene expression at transcriptional, post-transcriptional, and translational levels, and modulates numerous pro-tumorigenic and tumor-suppressive signal transduction pathways. Even though extensive research over the last two decades using various in vitro and in vivo models has established the pivotal role of AEG-1 in HCC, effective targeting of AEG-1 as a therapeutic intervention for HCC is yet to be achieved in the clinic. Targeted delivery of AEG-1 small interfering ribonucleic acid (siRNA) has demonstrated desired therapeutic effects in mouse models of HCC. Peptidomimetic inhibitors based on protein-protein interaction studies has also been developed recently. Continuous unraveling of novel mechanisms in the regulation of HCC by AEG-1 will generate valuable knowledge facilitating development of specific AEG-1 inhibitory strategies. The present review describes the current status of AEG-1 in HCC gleaned from patient-focused and bench-top studies as well as transgenic and knockout mouse models. We also address the challenges that need to be overcome and discuss future perspectives on this exciting molecule to transform it from bench to bedside.

AEG-1 Regulates TWIK-1 Expression as an RNA-Binding Protein in Astrocytes

AEG-1, also called MTDH, has oncogenic potential in numerous cancers and is considered a multifunctional modulator because of its involvement in developmental processes and inflammatory and degenerative brain diseases. However, the role of AEG-1 in astrocytes remains unknown. This study aimed to investigate proteins directly regulated by AEG-1 by analyzing their RNA expression patterns in astrocytes transfected with scramble shRNA and AEG-1 shRNA. AEG-1 knockdown down-regulated TWIK-1 mRNA. Real-time quantitative PCR (qPCR) and immunocytochemistry assays confirmed that AEG-1 modulates TWIK-1 mRNA and protein expression. Electrophysiological experiments further revealed that AEG-1 further regulates TWIK-1-mediated potassium currents in normal astrocytes. An RNA immunoprecipitation assay to determine how AEG-1 regulates the expression of TWIK-1 revealed that AEG-1 binds directly to TWIK-1 mRNA. Furthermore, TWIK-1 mRNA stability was significantly increased upon overexpression of AEG-1 in cultured astrocytes (p < 0.01). Our findings show that AEG-1 serves as an RNA-binding protein to regulate TWIK-1 expression in normal astrocytes.

Assessment of Current Gene Therapy Practices in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer and the fifth most common cancer worldwide. HCC is recognized as the fourth most common cause of cancer related deaths worldwide due to the lack of effective early diagnostic tools, which often leads to individuals going undiagnosed until the cancer has reached late stage development. The current FDA approved treatments for late stage HCC provide a minimal increase in patient survival and lack tumor specificity, resulting in toxic systemic side effects. Gene therapy techniques, such as chimeric antigen receptor (CAR)-T Cells, viral vectors, and nanoparticles, are being explored as novel treatment options in various genetic diseases. Pre-clinical studies using gene therapy to treat in vitro and in vivo models of HCC have demonstrated potential efficacy for use in human patients. This review highlights genetic targets, techniques, and current clinical trials in HCC utilizing gene therapy.

MicroRNA-499 Suppresses the Growth of Hepatocellular Carcinoma by Downregulating Astrocyte Elevated Gene-1

The aim of this study is to investigate the role of microRNA-499 (miR-499) in hepatocellular carcinoma tumor growth and the underlying molecular mechanisms. The expression of miR-499 was significantly decreased in hepatocellular carcinoma tissues compared with that in adjacent normal tissues. Furthermore, miR-499 overexpression in HEPG2 cell was related to the tumor growth in nude mice xenograft models. Likewise, miR-499 mimic or inhibitor decreased or accelerated cell proliferation, respectively. Mechanistically, miR-499 directly targeted the 3'- untranslated region of astrocyte elevated gene-1 and downregulate astrocyte elevated gene-1 expression. Restoration of astrocyte elevated gene-1 expression in hepatocellular carcinoma cells reversed the inhibitory effect of miR-499 on cell growth. In addition, astrocyte elevated gene-1 and miR-499 expression were inversely correlated in human and mice hepatocellular carcinoma tissues. Our study identified miR-499 as a tumor-suppressive miR in hepatocellular carcinoma, thus providing a candidate therapeutic target for the future diagnosis or treatment of hepatocellular carcinoma.

[Calcium channel blocker diltizem transiently inhibits migration and up-regulates metadherin expression in hepatocellular carcinoma cells in vitro]

OBJECTIVE

To investigate the effect of calcium channel blocker diltizem in reversing multi-drug resistance (MDR) and on metadherin expression in hepatocellular carcinoma cells and explore the molecular mechanism.

METHODS

Hepatocellular carcinoma MHCC97H and 7402 cells were treated with diltiazem hydrochloride, a calcium channel blocker (0, 25, 50, 100, 200, and 400 μmol/L), for 12, 24, or 48 h. Wound healing assay was employed to assess the changes in the mobility and migration of the cells following the treatments, and the changes in the expression levels of metadherin mRNA and protein and P-gp protein were determined using RT-PCR and immunocytochemistry.

RESULTS

Diltiazem hydrochloride could transiently inhibit the migration and movement of MHCC97H and 7402 cells in vitro in a time-and concentration-dependent manner (P < 0.05). Diltiazem hydrochloride at different concentrations also transiently up-regulated the expressions of metadherin mRNA and protein but did not inhibit the expression of P-gp protein in MHCC97H and 7402 cells.

CONCLUSIONS

Calcium channel blocker can transiently inhibit the migration of hepatocellular carcinoma cells in vitro and up-regulate the expression of metadherin mRNA and protein through a feedback mechanism, suggesting the potential risk of calcium channel blockers for promoting tumor progression during the treatment of malignant tumors.

Lipopolysaccharide-induced expression of astrocyte elevated gene-1 promotes degeneration and inflammation of chondrocytes via activation of nuclear factor-κB signaling

Osteoarthritis is an inflammatory disease characterized by joint degeneration and inflammation. Astrocyte elevated gene-1 (AEG-1) has been suggested as a novel inflammation-related factor in the pathological processes of various inflammatory diseases. To date, little is known about the role of AEG-1 in osteoarthritis. The aim of the present study was to explore the potential role of AEG-1 in the regulation of lipopolysaccharide-induced apoptosis and inflammation of chondrocytes. The results showed that AEG-1 expression was significantly upregulated in chondrocytes following exposure to lipopolysaccharide. Knockdown of AEG-1 increased the survival and decreased the expression of matrix metalloproteinases in chondrocytes treated with lipopolysaccharide. Moreover, silencing of AEG-1 restricted the lipopolysaccharide-induced production of proinflammatory cytokines. In contrast, AEG-1 overexpression caused opposite effects. Notably, we found that AEG-1 inhibition blocked the lipopolysaccharide-induced activation of nuclear factor-κB signaling through impeding the nuclear translocation of nuclear factor-κB p65 subunit. Additionally, inhibition of nuclear factor-κB partially reversed the AEG-1-mediated promotion of lipopolysaccharide-induced inflammatory injury in chondrocytes. In conclusion, our results demonstrate that inhibition of AEG-1 expression attenuates lipopolysaccharide-induced degeneration and inflammation of chondrocytes through suppressing the activation of nuclear factor-κB signaling. This work therefore highlights a potential role of AEG-1 in the pathogenesis of osteoarthritis, and indicates its potential as a therapeutic target.

MicroRNA-625-3p promotes the proliferation, migration and invasion of thyroid cancer cells by up-regulating astrocyte elevated gene 1

BACKGROUND

Thyroid cancer is the most common malignancy in human endocrine system. This study aimed to investigate the effects of microRNA-625-3p (miR-625-3p) on thyroid cancer cell proliferation, migration, invasion and apoptosis, as well as underlying potential mechanism.

METHODS

The relative expressions of miR-625-3p in tumor tissues and adjacent normal tissues of 20 patients with papillary thyroid cancer (PTC) were assessed using qRT-PCR. Cell transfection was used to up-regulate or down-regulate the expressions of miR-625-3p in thyroid cancer SW579 and TPC-1 cells. Effects of miR-625-3p overexpression or suppression on SW579 and TPC-1 cell viability, migration, invasion and apoptosis were detected respectively. The regulatory effect of miR-625-3p on astrocyte elevated gene 1 (AEG-1) expression was also analyzed. Then, the roles of AEG-1 in SW579 and TPC-1 cell proliferation, migration, invasion and apoptosis, as well as Wnt/β-catenin and c-Jun N-terminal kinase (JNK) pathways activation, were evaluated.

RESULTS

miR-625-3p had high expressions in tumor tissues, compared to adjacent normal tissues. Overexpression of miR-625-3p significantly promoted SW579 and TPC-1 cell proliferation, migration and invasion but had no influence on cell apoptosis. Knockdown of miR-625-3p had opposite effects, but induced cell apoptosis. AEG-1 was up-regulated by miR-625-3p overexpression and participated in the effects of miR-625-3p on SW-579 and TPC-1 cells. In addition, overexpression of AEG-1 induced the activation of Wnt/β-catenin and JNK pathways in SW579 and TPC-1 cells.

CONCLUSION

miR-625-3p promoted proliferation, migration and invasion of thyroid cancer cells by enhancing the expression of AEG-1 and activating downstream Wnt/β-catenin and JNK pathways.

Silencing of astrocyte elevated gene-1 inhibits proliferation and migration of melanoma cells and induces apoptosis

Melanoma is an aggressive skin malignancy with a high mortality. Astrocyte elevated gene-1 (AEG-1), a downstream target of Ras and c-Myc, has been implicated in the development of multiple tumours, but its role in melanoma remains unclear. In the present study, the role of AEG-1 in melanoma was explored through AEG-1 silencing. Our results showed that silencing AEG-1 inhibited the proliferation of melanoma cells, induced cell cycle arrest, and reduced levels of cyclin A, cyclin B, cyclin D1, cyclin E, and cyclin-dependent kinase 2. AEG-1silencing also induced apoptosis in melanoma cells and altered the levels of cleaved caspase-3, B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein. Moreover, silencing AEG-1 suppressed the migration and invasion of melanoma cells, reduced the expressions and activities of matrix metallopeptidase (MMP)-2 and MMP-9, and inhibited the activation of the Wnt/β-catenin signalling pathway in melanoma cells. Furthermore, in vivo experiments revealed that AEG-1 silencing inhibited the growth of melanoma xenografts in nude mice. In summary, our study demonstrates an oncogenic role of AEG-1 in melanoma and suggests that AEG-1 may serve as a potential therapeutic target in the treatment of melanoma.

Depletion of astrocyte elevated gene-1 suppresses tumorigenesis through inhibition of Akt activity in bladder cancer cells

Astrocyte elevated gene-1 (AEG-1) has been reported to promote tumorigenesis, however the molecular mechanisms by which AEG-1-induced bladder cancer progression has remained elusive. Here, we identified that depletion of AEG-1 in bladder cancer cells suppressed cell growth. Moreover, we observed that down-regulation of AEG-1 induced apoptosis and inhibited cell migration and invasion. Furthermore, depletion of AEG-1 inhibited Akt activity and suppressed Bcl-2 expression, but upregulated the levels of p21 and p27. Our findings reveal that AEG-1 carries out its oncogenic function via activation of the Akt pathway. Therefore, inhibition of AEG-1 could be a novel treatment approach for bladder cancer.

Astrocyte elevated gene-1 promotes invasion and epithelial-mesenchymal transition in bladder cancer cells through activation of signal transducer and activator of transcription 3

OBJECTIVES

To determine the impact of astrocyte elevated gene-1 on the invasion and epithelial-mesenchymal transition of bladder cancer cells in vitro and metastasis in vivo.

METHODS

Gain- and loss-of-function studies were carried out to investigate the biological roles of astrocyte elevated gene-1 in bladder cancer cell invasion, epithelial-mesenchymal transition and lung metastasis. The mechanism underlying the activity of astrocyte elevated gene-1 was examined.

RESULTS

Overexpression of astrocyte elevated gene-1 led to a significant increase in the invasive ability of UMUC3 and T24 bladder cancer cells in Matrigel invasion assays. In contrast, silencing of astrocyte elevated gene-1 restrained bladder cancer cell invasion. Overexpression of astrocyte elevated gene-1 downregulated E-cadherin and upregulated vimentin and Twist1, while silencing of astrocyte elevated gene-1 exerted an opposite effect. Mechanistically, astrocyte elevated gene-1 overexpression promoted the phosphorylation of signal transducer and activator of transcription 3 in bladder cancer cells. Treatment with WP1066, a specific signal transducer and activator of transcription 3 inhibitor, significantly abolished astrocyte elevated gene-1-induced invasion and epithelial-mesenchymal transition in UMUC3 cells. In vivo studies showed that astrocyte elevated gene-1 overexpression stimulated the growth of UMUC3 xenograft tumors and lung metastasis.

CONCLUSIONS

Astrocyte elevated gene-1 shows the ability to promote bladder cancer metastasis, which is causally linked to induction of signal transducer and activator of transcription 3 activation and epithelial-mesenchymal transition. Therefore, targeting astrocyte elevated gene-1 might offer therapeutic benefits in treating metastatic bladder cancer.

Knockdown of astrocyte elevated gene-1 inhibited cell growth and induced apoptosis and suppressed invasion in ovarian cancer cells

Emerging evidence has demonstrated that AEG-1 (astrocyte elevated gene-1) plays a pivotal oncogenic role in tumorigenesis. However, the molecular mechanism by which AEG-1 exerts its oncogenic function is elusive in ovarian cancer. To explore the role and molecular insight on AEG-1-mediated tumorigenesis in ovarian cancer, multiple approaches are performed including MTT assay, flow cytometry for apoptosis and cell cycle assay, gene transfection, real-time RT-PCR, Western blotting, and Transwell assay. Our MTT assay showed that knockdown of AEG-1 by its siRNA significantly inhibited cell growth in ovarian cancer cells. Moreover, AEG-1 siRNA treatment induced G₀/G₁ cell cycle arrest and triggered cell apoptosis in ovarian cancer cells. Notably, inhibition of AEG-1 suppressed cell migration and invasion in ovarian cancer cells. Intriguingly, we identified that knockdown of AEG-1 remarkably inhibited the activation of Akt pathway. Our results also validated that knockdown of AEG-1 inhibited the expression of MMP-2 and VEGF, which could lead to inhibition of cell migration and invasion. These data suggest that AEG-1 could be a potential therapeutic target for the treatment of ovarian cancer.

miR-217 suppresses proliferation, migration, and invasion promoting apoptosis via targeting MTDH in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has frequent incidence and the third highest mortality rate among cancers in the world. This study aimed to clarify the roles of miR-217 and metadherin (MTDH) in HCC. First, we identified that miR-217 expression was downregulated and MTDH expression was upregulated in the HCC tissues. Functional studies revealed that miR-217 negatively regulated MTDH expression via binding to the 3'-untranslated region of MTDH mRNA in the HCC cells. In our further studies, the miR-217 overexpression resulted in downregulation of MTDH expression in HCC cells. The miR-217 overexpression in HCC cells suppressed proliferation, migration, and invasion inducing apoptosis. Taken together, our study provides the initial evidence that the increase of MTDH expression is associated with the decrease of miR-217 expression in HCC. This study also suggests that miR-217 inhibits malignant progression of HCC in vitro and may be used for miRNA-based therapy, possibly via directly targeting MTDH.

AEG-1 is associated with hypoxia-induced hepatocellular carcinoma chemoresistance via regulating PI3K/AKT/HIF-1alpha/MDR-1 pathway

Hypoxia is a common characteristic of hepatocellular carcinoma (HCC) associated with reduced response to chemotherapy, thus increasing the probability of tumor recurrence. Astrocyte elevated gene-1 (AEG-1) has been involved in a wide array of cancer progression including proliferation, chemoresistance, angiogenesis and metastasis, but its effect on HCC chemoresistance induced by hypoxia is unclear. In this study, expression of AEG-1 and multiple drug resistance (MDR-1) were examined in HCC using immunohistochemical staining and RT-PCR. Furthermore, their expression levels were detected in HCC HepG2 cells in normoxia or hypoxia via RT-PCR and Western blot assays. Specific shRNAs were used to silence AEG-1 expression in HepG2 cells. Results showed AEG-1 and MDR-1 expression were higher in HCC tissues than in adjacent normal tissues. Incubation of HepG2 cells in hypoxia increased expression of AEG-1 and MDR-1, compared to incubation in normoxia. Exposure to hypoxia blunted sensitivity of HepG2 cells to Adriamycin, 5-fluorouracil and cis-platinum, as evidenced by modest alterations in cell viability and apoptosis rate, however the sensitivity was elevated with AEG-1 knockdown. PI3K/AKT/HIF-1/MDR-1 pathway was attenuated following AEG-1 knockdown in hypoxia. Based on these data, it was suggested that AEG-1 is associated with hypoxia-induced hepatocellular carcinoma chemoresistance via regulating PI3K/AKT/HIF-1/MDR-1 pathway. This study uncovered a novel potential target for development of an effective therapy against hypoxia-induced HCC chemoresistance.

AEG-1/MTDH/LYRIC: A Promiscuous Protein Partner Critical in Cancer, Obesity, and CNS Diseases

Since its original discovery in 2002, AEG-1/MTDH/LYRIC has emerged as a primary regulator of several diseases including cancer, inflammatory diseases, and neurodegenerative diseases. AEG-1/MTDH/LYRIC has emerged as a key contributory molecule in almost every aspect of cancer progression, including uncontrolled cell growth, evasion of apoptosis, increased cell migration and invasion, angiogenesis, chemoresistance, and metastasis. Additionally, recent studies highlight a seminal role of AEG-1/MTDH/LYRIC in neurodegenerative diseases and obesity. By interacting with multiple protein partners, AEG-1/MTDH/LYRIC plays multifaceted roles in the pathogenesis of a wide variety of diseases. This review discusses the current state of understanding of AEG-1/MTDH/LYRIC regulation and function in cancer and other diseases with a focus on its association/interaction with several pivotal protein partners.