Astrocyte elevated gene-1 regulates CCL3/CCR5-induced epithelial-to-mesenchymal transition via Erk1/2 and Akt signaling in cardiac myxoma

HIV-1 gp120 amplifies astrocyte elevated gene-1 activity to compromise the integrity of the outer blood-retinal barrier

OBJECTIVE

This study aims to investigate the functions and mechanistic pathways of Astrocyte Elevated Gene-1 (AEG-1) in the disruption of the blood-retinal barrier (BRB) caused by the HIV-1 envelope glycoprotein gp120.

DESIGN

We utilized ARPE-19 cells challenged with gp120 as our model system.

METHODS

Several analytical techniques were employed to decipher the intricate interactions at play. These included PCR, Western blot, and immunofluorescence assays for the molecular characterization, and transendothelial electrical resistance (TEER) measurements to evaluate barrier integrity.

RESULTS

We observed that AEG-1 expression was elevated, whereas the expression levels of tight junction proteins ZO-1, Occludin, and Claudin5 were downregulated in gp120-challenged cells. TEER measurements corroborated these findings, indicating barrier dysfunction. Additional mechanistic studies revealed that the activation of NFκB and MMP2/9 pathways mediated the AEG-1-induced barrier destabilization. Through the use of lentiviral vectors, we engineered cell lines with modulated AEG-1 expression levels. Silencing AEG-1 alleviated gp120-induced downregulation of tight junction proteins and barrier impairment while concurrently inhibiting the NFκB and MMP2/9 pathways. Conversely, overexpression of AEG-1 exacerbated these pathological changes, further compromising the integrity of the BRB.

CONCLUSION

Gp120 upregulates the expression of AEG-1 and activates the NFκB and MMP2/9 pathways. This in turn leads to the downregulation of tight junction proteins, resulting in the disruption of barrier function.

CCL3-CCR5 axis promotes cell migration and invasion of colon adenocarcinoma via Akt signaling pathway

BACKGROUND

Infiltration of tumor-associated macrophages (TAMs) can promote tumorigenesis and development. C-C motif chemokine ligand 3 (CCL3) was reported to be derived from TAMs and tumor cells and facilitate the progression of several cancers. Nevertheless, whether CCL3 can be derived from TAMs and tumor cells of colon adenocarcinoma (COAD) is unclarified.

METHODS

Peripheral blood monocytes-derived macrophages were polarized by the conditioned medium from COAD cells to establish TAM-like macrophages (TAM1/2). RT-qPCR and western blotting were used for detection of expression levels of CCL3 and its receptors C-C motif chemokine receptor 1 (CCR1) and CCR5 in TAM1/2 and COAD cells. Immunofluorescence staining was utilized for evaluating CCL3, CD163 and CCR5 expression. The Akt signaling pathway-associated protein levels were measured by western blotting. Transwell assays were used for assessing cell migration and invasiveness.

RESULTS

CCL3 displayed a high level in TAMs and cancer cells of COAD. CCL3 activated the Akt signaling pathway by binding to CCR5. CCL3-CCR5 axis facilitated COAD cell migration and invasiveness by activating the Akt signaling. CCL3 derived from both TAMs and cancer cells contributed to the malignant behaviors of COAD cells. High expression of CCL3/CCR5 was closely associated with poor prognoses of COAD patients.

CONCLUSION

CCL3-CCR5 interaction promotes cell migration and invasiveness, and functions as a prognostic biomarker for COAD.

Colorectal cancer cells promote osteoclastogenesis and bone destruction through regulating EGF/ERK/CCL3 pathway

Bone metastasis of colorectal cancer (CRC) cells leads to osteolysis. Aberrant activation of osteoclasts is responsible for bone resorption in tumor. In general, bone marrow-derived monocytes (BMMs) differentiate into osteoclasts, however, how CRC cells interact with BMMs and how to regulate the differentiation is elusive. We here report that CRC cells promote bone resorption in bone metastasis. Transcriptomic profiling revealed CCL3 up-regulated in MC-38 conditional medium treated BMMs. Further investigation demonstrated that CCL3 produced by BMMs facilitated cell infusion and thus promoted the osteoclastogenesis. In addition, CRC cells derived EGF stimulated the production of CCL3 in BMMs through activation of ERK/CREB pathway. Blockage of EGF or CCL3 can efficiently attenuate the osteolysis in bone metastasis of CRC.

Amyloid β precursor protein silencing attenuates epithelial‑mesenchymal transition of nasopharyngeal carcinoma cells via inhibition of the MAPK pathway

Advances in the treatment of nasopharyngeal carcinoma (NPC) have significantly improved the local control rate; however, distant metastasis remains a principal cause of mortality. Previous studies have demonstrated that the expression levels of amyloid β precursor protein (APP) are increased in NPC. The present study aimed to investigate the association between APP and the development of NPC. In order to knockdown APP expression, an APP-small interfering RNA vector was synthesized and transfected into SUNE-1 cells. Cell Counting Kit-8 assay was performed to assess cell viability. The migratory and invasive abilities of SUNE-1 cells were examined by wound healing and Transwell assays, respectively. Reverse transcription-quantitative polymerase chain reaction and western blotting were performed to measure the mRNA and protein expression levels of APP, and additional factors involved in epithelial-mesenchymal transition (EMT) and in the mitogen-activated protein kinase (MAPK) signaling pathway. APP silencing significantly suppressed cell viability, migration and invasion. In addition, APP interference downregulated the expression levels of metastasis-associated 1, matrix metalloproteinase (MMP)-2 and MMP-9; however, knockdown of APP led to upregulation of tissue inhibitor of metalloproteinases 2 and inhibited EMT. The phosphorylation levels of p38, extracellular signal-regulated kinases 1/2 and c-Jun N-terminal kinases 1/2 were decreased following downregulation of APP. The present results suggested that APP knockdown may significantly inhibit the development of NPC by suppressing cell viability, migration and invasion, and by inhibiting the EMT process via downregulation of the MAPK signaling pathway. Therefore, APP may facilitate the development of a novel gene therapy for the treatment of NPC.

BAG3 contributes to HGF-mediated cell proliferation, migration, and invasion via the Egr1 pathway in gastric cancer

INTRODUCTION:

Bcl2-associated athanogene 3 (BAG3) is elevated in several types of cancers. However, the role of BAG3 in progression of gastric cancer is unknown. Therefore, the present study aims to find out the role of BAG3 in hepatocyte growth factor (HGF)-mediated tumor progression and the molecular mechanisms by which HGF regulates BAG3 expression.

METHODS:

BAG3 mRNA and protein were measured using reverse transcription polymerase chain reaction and Western blot in the 2 human gastric cancer cell lines, NUGC3 and MKN28, treated with or without HGF. The effects of BAG3 knockdown on cell proliferation, cell invasion, and apoptosis were analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the in vitro 2-chamber invasion assay, and flow cytometry in BAG3 short hairpin RNA (shRNA)-transfected cells and control cells. The signaling pathways involved in BAG3 that are regulated by HGF were analyzed. The chromatin immunoprecipitation assay was used to determine binding of Egr1 to the BAG3 promoter.

RESULTS:

BAG3 mRNA and protein levels were increased following treatment with HGF. HGF-mediated BAG3 upregulation increased cell proliferation and cell invasion; however, it decreased apoptosis. HGF-mediated BAG3 upregulation is regulated by an ERK and Egr1-dependent pathway. BAG3 may have an important role in HGF-mediated cell proliferation and metastasis in gastric cancer through an ERK and Egr1-dependent pathway.

CONCLUSION:

This pathway may provide novel therapeutic targets and provide information for further identification of other targets of therapeutic significance in gastric cancer.

Silencing of Astrocyte elevated gene-1 (AEG-1) inhibits proliferation, migration, and invasiveness, and promotes apoptosis in pancreatic cancer cells

To investigate the role of Astrocyte elevated gene-1 (AEG-1) in the development and progress of pancreatic cancer, short hairpin RNA (shRNA) was inserted into the RNA interference vector to knock-down the endogenous AEG-1 in two pancreatic cancer cell lines: AsPC-1 and PANC-1. Our results showed that silencing of AEG-1 suppressed the proliferation, colony formation ability, and cell stemness of AsPC-1 and PANC-1 cells, and inhibited their G1-to-S phase transition. Results from apoptosis assay showed that knock-down of AEG-1 led to cell apoptosis. The expression of anti-apoptotic Bcl-2 was downregulated and that of the pro-apoptotic Bax and cleaved caspase-3 was upregulated in AEG-1-silenced pancreatic cancer cells. Further, the capability of AEG-1-silenced cells to migrate and to invade through the Matrigel-coated membrane was weaker, and the expression of matrix metallopeptidase 2 (MMP-2) and MMP-9 were decreased. Moreover, the AKT-β-catenin signaling pathway was inhibited in the cells with knock-down of AEG-1. In addition, the growth of xenograft tumors formed by AsPC-1 and PANC-1 cells was suppressed by AEG-1 shRNA. In conclusion, our study demonstrates that pancreatic cancer cells require AEG-1 to maintain their survival and metastasis, suggesting AEG-1 as a potential target for the treatment of pancreatic cancers.

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.

miR‑96 inhibits EMT by targeting AEG‑1 in glioblastoma cancer cells

The induction of epithelial to mesenchymal transition (EMT) is important for carcinogenesis and cancer progression. Previous studies have estimated that microRNA (miRNA/miR) expression is associated with EMT via the regulation of the expression of target genes. miR-96 has been reported to exhibit a correlation with the EMT process. However, the functional role of miR-96 and its mechanism in glioblastoma multiforme (GBM) remains to be completely elucidated. The objective of the present study was to investigate the functional role and mechanism of miR-96 in the migration and invasion, in addition to proliferation, apoptosis and cell cycle distribution, of GBM. In the present study, the results suggested that the introduction of miR-96 significantly inhibited the migration and invasion, in addition to proliferation and cell cycle progression, of GBM cells and promoted their apoptosis in vitro, leading to the hypothesis that miR-96 may be a potential tumor suppressor. It was subsequently confirmed that astrocyte elevated gene-1 (AEG-1) was a direct target gene of miR-96, using a luciferase assay and reverse transcription-quantitative polymerase chain reaction analysis, in addition to western blotting. miR-96 was observed to downregulate the expression of AEG-1 at the mRNA and protein levels. Notably, AEG-1 may suppress EMT by increasing the expression levels of E-cadherin, an epithelial marker, and decreasing the expression levels of vimentin, a mesenchymal marker. Therefore, it was concluded that miR-96 may impede the EMT process by downregulating AEG-1 in GBM. Additionally, it was observed that inhibition of AEG-1 led to a similar effect compared with overexpression of miR-96 in GBM. In conclusion, the results of the present study demonstrated that miR-96 may act as a tumor suppressor by regulating EMT via targeting of AEG-1, suggesting that miR-96 may be a potential biomarker and anticancer therapeutic target for GBM in the future.

Astrocyte elevated gene-1 promotes tumour growth and invasion by inducing EMT in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common human malignancy with a high incidence rate and poor prognosis. Although astrocyte elevated gene 1 (AEG-1) expression is up-regulated in various human cancers and plays an important role in carcinogenesis and tumour progression, the impact of AEG-1 on the development and progression of OSCC remains unclear. Accordingly, this study aims to clarify the biological significance of AEG-1 in OSCC. We found AEG-1 to be overexpressed in OSCC tissues compared to normal oral mucosa. Knockdown or overexpression of AEG-1 in OSCC cell lines showed that AEG-1 is important for tumour growth, apoptosis, drug tolerance, and maintaining epithelial-mesenchymal transition (EMT)-mediated cell migration and invasion in vitro. Moreover, in a xenograft-mouse model generated by AEG-1-overexpressing SCC15 cells, we found that higher expression of AEG-1 promoted tumour growth, angiogenesis, and EMT in vivo. These findings provide mechanistic insight into the role of AEG-1 in regulating OSCC tumour growth, apoptosis, drug tolerance, and invasion, as well as AEG-1-induced activation of p38 and NF-κB signalling, suggesting that AEG-1 is an important prognostic factor and therapeutic target for OSCC.

Astrocyte elevated gene-1 (AEG-1) and the A(E)Ging HIV/AIDS-HAND

Recent attempts to analyze human immunodeficiency virus (HIV)-1-induced gene expression changes in astrocytes uncovered a multifunctional oncogene, astrocyte elevated gene-1 (AEG-1). Our previous studies revealed that AEG-1 regulates reactive astrocytes proliferation, migration and inflammation, hallmarks of aging and CNS injury. Moreover, the involvement of AEG-1 in neurodegenerative disorders, such as Huntington's disease and migraine, and its induction in the aged brain suggest a plausible role in regulating overall CNS homeostasis and aging. Therefore, it is important to investigate AEG-1 specifically in aging-associated cognitive decline. In this study, we decipher the common mechanistic links in cancer, aging and HIV-1-associated neurocognitive disorders that likely contribute to AEG-1-based regulation of astrocyte responses and function. Despite AEG-1 incorporation into HIV-1 virions and its induction by HIV-1, tumor necrosis factor-α and interleukin-1β, the specific role(s) of AEG-1 in astrocyte-driven HIV-1 neuropathogenesis are incompletely defined. We propose that AEG-1 plays a central role in a multitude of cellular stress responses involving mitochondria, endoplasmic reticulum and the nucleolus. It is thus important to further investigate AEG-1-based cellular and molecular regulation in order to successfully develop better therapeutic approaches that target AEG-1 to combat cancer, HIV-1 and aging.

Expression of chemokine receptor CXCR4 is closely correlated with clinical outcome in human nasopharyngeal carcinoma

The CXC chemokine receptor 4 (CXCR4) has been reported to be involved in the development and progression of nasopharyngeal carcinoma (NPC). However, the role of CXCR4 in clinical outcome and prognosis of NPC patients remains controversial. In the present study, we investigated and reviewed the expression of CXCR4 in NPC tissues and then analyzed the definitive role of CXCR4 in clinical outcome and prognosis. Here, we found that the expression level of CXCR4 was significantly higher in NPC cancer specimens (61/98) than that in paired non-tumor tissues (p < 0.001). Together with our pathological analysis, statistic analysis revealed that CXCR4 expression was indeed closely correlated with UICC stage (p = 0.000), N stage (p = 0.019), and metastasis (p = 0.000). Most importantly, the systematic review combined with our survival and multivariate analysis that revealed high expression of CXCR4 was obviously associated with poor overall survival (OS) (p = 0.000) and progression-free survival (PFS) (p = 0.000) and can act as an independent prognostic factor in NPC patients. In conclusion, this study suggests that CXCR4 is highly activated and expressed in the development of NPC and may be recommended as an indicator in the diagnosis of NPC. Thus, targeting of CXCR4 gene or protein could be used as a potential therapy for NPC.

BAG3 regulates cell proliferation, migration, and invasion in human colorectal cancer

Bcl2-associated athanogene 3 (BAG3) has been reported to be elevated in various tumors. However, it is unclear whether BAG3 has a functional role in the initiation and progression of colorectal cancer (CRC). Here, we collected CRC samples and cell lines to validate the pathway by using gene and protein assays. RT-PCR showed that the expression of BAG3 mRNA in CRC tissues was obviously higher than that in non-tumor tissues (p < 0.001). Immunohistochemical analysis showed that immunoreactivity of BAG3 was found in most CRC tissues and strongly correlated with TNM stage (p = 0.001), differentiation (p = 0.003), and metastasis (p = 0.010). Low expression of BAG3 in HCT-8 significantly reduced cellular proliferation, migration, and invasion. The analysis of in vitro cell showed that HCT-8 cells were exposed to si-BAG3, and its growth was inhibited depending on modulation of cell cycle G1/S checkpoints and cell cycle regulators, involving cyclin D1, cyclin A2, and cyclin B1. Furthermore, suppression of the epithelial-mesenchymal transition (EMT) by si-BAG3 is linked to the decreased expression of E-cadherin and the increased expression of N-cadherin, vimentin, and MMP9. In conclusion, in the present study, we demonstrated that BAG3 overexpression plays a critical role in cell proliferation, migration, and invasion of colorectal cancer. Our data suggests targeted inhibition of BAG3 may be useful for patients with CRC.

The Crucial Role of Cyclin-Dependent Kinase-5-Ataxia-Telangiectasia Mutated Axis in ICH-Induced Neuronal Injury of Rat Model

Cyclin-dependent kinase 5 (CDK5) and ataxia-telangiectasia mutated (ATM) are involved in normal human neurodevelopment and serves as a switch between neuronal survival and death. However, the molecular mechanisms underlying CDK5-ATM-induced neuronal injury caused by intracerebral hemorrhage (ICH) remain unclear. In this work, we used rat ICH models and thrombin-induced cell models to investigate the potential role of CDK5-ATM signals. Our findings revealed that CDK5 protein levels and kinase activities (p-histone H1 expression) were enforced in hematoma-surrounding neuron tissues following ICH. Besides, the expression of p25, p-ATM, and active caspase-3 protein was also upregulated after ICH. According to in vitro assays, the expression of CDK5, p-ATM, and active caspase-3 was all upregulated in cell viability-decreasing ICH cell models. However, blocking of either CDK5 or ATM suppressed the phosphorylation of ATM and the expression of active caspase-3, and attenuated the inhibition of neuronal survival. When p35/p25 was silenced, CDK5-ATM pathway was further inhibited, and cell viability was obviously ameliorated. In conclusion, this work suggested that ATM could be phosphorylated by CDK5 to induce the active caspase-3 and neuronal injury when intracerebral hemorrhage or ischemia occurred. Thus, the CDK5-AMT signal pathway has an important role in ICH process and may be a therapeutic target to prevent brain injury.