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

Metadherin-mediated mechanisms in human malignancies

Metadherin (MTDH) has been recognized as a novel protein that is critical for the progression of multiple types of human malignancies. Studies have reported that MTDH enhances the metastatic potential of cancer cells by regulating multiple signaling pathways. miRNAs and various tumor-related proteins have been shown to interact with MTDH, making it a potential therapeutic target as well as a biomarker in human malignancies. MTDH plays a critical role in inflammation, angiogenesis, hypoxia, epithelial-mesenchymal transition and autophagy. In this review, we present the function and mechanisms of MTDH for cancer initiation and progression.

The Scope of Astrocyte Elevated Gene-1/Metadherin (AEG-1/MTDH) in Cancer Clinicopathology: A Review

Since its initial cloning in 2002, a plethora of studies in a vast number of cancer indications, has strongly established AEG-1 as a bona fide oncogene. In all types of cancer cells, overexpression and knockdown studies have demonstrated that AEG-1 performs a seminal role in regulating proliferation, invasion, angiogenesis, metastasis and chemoresistance, the defining cancer hallmarks, by a variety of mechanisms, including protein-protein interactions activating diverse oncogenic pathways, RNA-binding promoting translation and regulation of inflammation, lipid metabolism and tumor microenvironment. These findings have been strongly buttressed by demonstration of increased tumorigenesis in tissue-specific AEG-1 transgenic mouse models, and profound resistance of multiple types of cancer development and progression in total and conditional AEG-1 knockout mouse models. Additionally, clinicopathologic correlations of AEG-1 expression in a diverse array of cancers establishing AEG-1 as an independent biomarker for highly aggressive, chemoresistance metastatic disease with poor prognosis have provided a solid foundation to the mechanistic and mouse model studies. In this review a comprehensive analysis of the current and up-to-date literature is provided to delineate the clinical significance of AEG-1 in cancer highlighting the commonality of the findings and the discrepancies and discussing the implications of these observations.

Effect of Huaier on Melanoma Invasion, Metastasis, and Angiogenesis

Malignant melanoma (MM) is a highly metastatic and malignant cancer. Developing potential drugs with good efficacy and low toxicity for MM treatment is needed. Huaier, extracted from the mushroom Trametes robiniophila Murr, has been widely used in clinical anticancer treatments in China. A previous work done by our group confirmed that Huaier could inhibit cell proliferation and induce apoptosis in human melanoma cells. The current study is aimed at investigating the effects of Huaier on melanoma metastasis and angiogenesis in vitro and in vivo and to explore its possible mechanism of action. Our results showed that Huaier not only significantly inhibited the metastasis of A375 cells at the concentration ranging from 4 to 16 mg/ml (P < 0.05), which were determined by the wound healing assay and transwell assay in vitro, but also suppressed the MM tumor growth and metastatic cells to the liver in A375-bearing mice after oral administration at the dose of 5 mg/kg (P < 0.05). In addition, Huaier treatment downregulated the expression of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), astrocyte-elevated gene-1 (AEG-1), and N-cadherin, while it upregulated E-cadherin expression in both the A375 cells and tumor tissues, which was detected using western blotting and RT-PCR (P < 0.05). Taken together, our data suggests that the antitumor and antimetastatic activities of Huaier are caused by the downregulation of the HIF-1α/VEGF and AEG-1 signaling pathways and by the inhibition of epithelial-mesenchymal transition (EMT). This study provides a new insight into the mechanism of Huaier on antimetastatic therapy and a new scientific basis for comprehensive treatment strategies for MM.

MTDH promotes metastasis of clear cell renal cell carcinoma by activating SND1-mediated ERK signaling and epithelial-mesenchymal transition

BACKGROUND

Metastasis is the principal cause of renal cell carcinoma-associated mortality. Metadherin (MTDH) was identified as a vital metastasis driver involved in the metastatic progression of various types of tumors, suggesting that MTDH is a prognostic metastatic biomarker and potential therapeutic target. The role and mechanism of MTDH in the metastatic progression of ccRCC have not yet been adequately explored.

RESULTS

MTDH was remarkably elevated in ccRCC tissues, especially in metastatic ccRCC tissues, compared with normal kidney tissues and correlated with advanced clinicopathological features and poor prognosis. MTDH activated ERK signaling and EMT, thus promoting the migration and invasion of ccRCC cells. The interaction between MTDH and SND1 at the protein level was confirmed using immunoprecipitation and immunofluorescence. Based on the analysis of datasets from GEO and TCGA, SND1 was remarkably increased in ccRCC, especially in metastatic ccRCC, and associated with advanced clinicopathological features and poor prognosis. Knockdown of SND1 mainly abolished the migration and invasion of ccRCC cells by blocking MTDH-mediated ERK and EMT signaling activation.

CONCLUSION

These results revealed that MTDH may be a prognostic metastatic biomarker of ccRCC that promotes ccRCC metastasis by activating SND1-mediated the ERK and EMT signaling pathways. MTDH may serve as an anti-tumor therapeutic target that can be applied for the clinical treatment of metastatic ccRCC.

METHODS

MTDH/SND1 mRNA expression in clear cell renal cell carcinoma (ccRCC) was comprehensively estimated by analysis of GEO-ccRCC and TCGA-KIRC datasets with R software and packages. MTDH protein expression was assessed in a total of 111 ccRCC patients from Peking University First Hospital by immunohistochemistry (IHC). In vitro migration and invasion assays were carried out, and an in vivo metastatic mouse model was developed to investigate the biological functions of MTDH in ccRCC cells. Correlation analysis, immunoprecipitation, western blotting and immunofluorescence were applied to explore the molecular mechanisms of MTDH in ccRCC.

miR-30e-5p represses angiogenesis and metastasis by directly targeting AEG-1 in squamous cell carcinoma of the head and neck

Metastasis is a critical determinant for the treatment strategy and prognosis in patients with squamous cell carcinoma of the head and neck (SCCHN). However, the mechanisms underlying SCCHN metastasis are poorly understood. Our study sought to determine the key microRNA and their functional mechanisms involved in SCCHN metastasis. For The Cancer Genome Atlas (TCGA) data analysis, quantitative PCR was used to quantify the level of miR‐30e‐5p in SCCHN and its clinical significance was further analyzed. A series of in vitro and in vivo experiments were applied to determine the effects of miR‐30e‐5p and its target AEG‐1 on SCCHN metastasis. A mechanism investigation further revealed that AEG‐1 was implicated in the angiogenesis and metastasis mediated by miR‐30e‐5p. Overall, our study confirms that miR‐30e‐5p is a valuable predictive biomarker and potential therapeutic target in SCCHN metastasis.

Long non-coding RNA highly up-regulated in liver cancer promotes epithelial-to-mesenchymal transition process in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is an oral and maxillofacial malignancy that exhibits high incidence worldwide. In diverse human cancers, the long non-coding RNA (lncRNA) highly up-regulated in liver cancer (HULC) is aberrantly expressed, but how HULC affects OSCC development and progression has remained mostly unknown. We report that HULC was abnormally up-regulated in oral cancer tissues and OSCC cell lines, and that suppression of HULC expression in OSCC cells not only inhibited the proliferation, drug tolerance, migration and invasion of the cancer cells, but also increased their apoptosis rate. Notably, in a mouse xenograft model, HULC depletion reduced tumorigenicity and inhibited the epithelial-to-mesenchymal transition process. Collectively, our findings reveal a crucial role of the lncRNA HULC in regulating oral cancer carcinogenesis and tumour progression, and thus suggest that HULC could serve as a novel therapeutic target for OSCC.

Prognostic and clinicopathologic significance of AEG-1/MTDH and E-cadherin expression in human gallbladder carcinoma

Astrocyte elevated gene-1 (AEG-1) and E-cadherin are associated with tumorigenesis and progression. The aim of this study is to investigate the expression of AEG-1 and E-cadherin in human gallbladder cancer (GBC) and explore their clinical and pathological significance. The expression of AEG-1 and E-cadherin protein were detected in 71 cases of human GBC and 22 cases of tumor-adjacent tissue by the immunohistochemical method. Our results demonstrate that the positive expression (high expression) rate of AEG-1 was 62.0% in human GBC which was higher than that in tumor-adjacent tissues (13.6%), P<0.001. The positive expression of AEG-1 protein was correlated with tumor TNM classification, histologic grade, and lymph node metastasis (P=0.037, P=0.033 and P=0.020, respectively). The positive expression rate of E-cadherin was 40.8% in GBC, which was lower than that in tumor-adjacent tissues (77.3%), P=0.003. Negative expression (Low expression) of E-Cadherin was significantly related with tumor TNM classification, histologic grade and lymphatic metastasis (P=0.028, P=0.003 and P=0.040, respectively). The expression of AEG-1 was negatively correlated with the expression of E-Cadherin (r=0.530, P<0.001). The log-rank test statistical analysis suggested that patients with positive expression of AEG-1 or negative expression of E-Cadherin protein had shorter overall survival time. Cox multivariate analysis showed that tumor TNM classification, histologic grade and lymphatic metastasis, AEG-1 and E-cadherin expression were independent factors for prognosis of GBC (P=0.013, P=0.019, P=0.001, P=0.011 and P=0.025 respectively). In conclusion, positive expression of AEG-1 and negative expression of E-Cadherin are markedly correlated with tumor TNM classification, histologic grade and lymphatic metastasis. The expression of AEG-1 was negatively correlated with the expression of E-Cadherin. Cox multivariate analysis showed that tumor TNM classification, histologic grade and lymphatic metastasis, positive expression of AEG-1 and negative expression of E-Cadherin were risk factors for prognosis of GBC. Detection of AEG-1 and E-Cadherin may be helpful to evaluate prognosis and infiltrative capability of gallbladder carcinoma.

MicroRNA‑655 suppresses cell proliferation and invasion in oral squamous cell carcinoma by directly targeting metadherin and regulating the PTEN/AKT pathway

MicroRNAs (miRNAs) are important regulators of a variety of biological processes and their dysregulation is closely related to cancer formation and progression. Therefore, examination of aberrantly expressed miRNAs in oral squamous cell carcinoma (OSCC) may provide important clues for the diagnosis and treatment of patients with OSCC. The aim of the present study was to determine miRNA (miR)‑655‑3p expression in OSCC tissues and cell lines, and to investigate the biological roles and mechanisms of miR‑655‑3p associated with OSCC. Data from the present study indicated that miR‑655 expression was significantly downregulated in human OSCC tissues and cell lines. Overexpression of miR‑655 attenuated cell proliferation and invasion in OSCC in vitro. Metadherin (MTDH) mRNA was predicted as a potential target of miR‑655 by bioinformatics analysis, and this was confirmed by luciferase reporter assay, reverse transcription‑quantitative polymerase chain reaction and western blot analysis. In OSCC tissues, MTDH was highly expressed and inversely correlated with miR‑655 expression levels. MTDH overexpression reversed the inhibitory effects of miR‑655 mimics in OSCC cells. Notably, the upregulation of miR‑655 expression inhibited the activation of the phosphatase and tensin homolog (PTEN)/RAC‑α serine/threonine‑protein kinase (AKT) pathway in OSCC cells. Therefore, these results may provide the first evidence that miR‑655 targets MTDH to inhibit proliferation and invasion of OSCC by inhibiting PTEN/AKT signaling. Thus, the restoration of miR‑655 expression may be a novel therapeutic strategy for patients with OSCC.