The zinc finger protein Miz1 suppresses liver tumorigenesis by restricting hepatocyte-driven macrophage activation and inflammation.

Chronic inflammation plays a central role in hepatocellular carcinoma (HCC), but the contribution of hepatocytes to tumor-associated inflammation is not clear. Here, we report that the zinc finger transcription factor Miz1 restricted hepatocyte-driven inflammation to suppress HCC, independently of its transcriptional activity. Miz1 was downregulated in HCC mouse models and a substantial fraction of HCC patients. Hepatocyte-specific Miz1 deletion in mice generated a distinct sub-group of hepatocytes that produced pro-inflammatory cytokines and chemokines, which skewed the polarization of the tumor-infiltrating macrophages toward pro-inflammatory phenotypes to promote HCC. Mechanistically, Miz1 sequestrated the oncoprotein metadherin (MTDH), preventing MTDH from promoting transcription factor nuclear factor κB (NF-κB) activation. A distinct sub-group of pro-inflammatory cytokine-producing hepatocytes was also seen in a subset of HCC patients. In addition, Miz1 expression inversely correated with disease recurrence and poor prognosis in HCC patients. Our findings identify Miz1 as a tumor suppressor that prevents hepatocytes from driving inflammation in HCC.

MiR-26a and miR-191 are upregulated while PLAG1 and HIF2 are downregulated in pleomorphic adenomas of the salivary glands compared to Warthin tumors.

BACKGROUND: Salivary gland tumors (SGTs) are a heterogenous group of pathologies, which still represents a challenge regarding differential diagnosis and therapy. Although histological findings govern SGTs management, detection of molecular alterations is emerging as an effective additional tool. The aim of this study was to analyze the relative expression levels of three micro RNAs (miR-26a, miR-26b, and miR-191), and three pro-oncogenic molecular markers (PLAG1, MTDH, and HIF2) in SGTs and normal salivary gland (NSG) tissues and evaluate them as potential differential diagnosis markers. METHODS: This cross-sectional study included 58 patients with SGTs (23 pleomorphic adenomas, 27 Warthin tumors, and 8 malignant SGTs) and 10 controls (normal salivary gland tissues). Relative gene expression levels of all investigated molecules were determined by reverse transcriptase-real-time polymerase chain reaction. RESULTS: All three micro RNAs exhibited highest expression levels in benign SGTs, whereas miR-26a And miR-191 were significantly more expressed in PAs compared to WTs (p = 0.045 and p = 0.029, respectively). PLAG1 And HIF2 were both overexpressed in WTs compared to PAs (p = 0.048 and p = 0.053, respectively). Bioinformatic analysis suggested that all investigated micro RNAs function as negative regulators of MTDH. CONCLUSION: The results of this study suggest that all three micro RNAs have a considerable negative impact on MTDH oncogene expression in malignant tumors, while the differences between levels of miR-26a, miR-191, PLAG1, and HIF2 in PA and WT represent possible differential diagnosis markers.

Gigantol protects retinal pigment epithelial cells against high glucose-induced apoptosis, oxidative stress and inflammation by inhibiting MTDH-mediated NF-kB signaling pathway.

OBJECTIVE: As a frequent complication of diabetes mellitus (DM), diabetic retinopathy (DR) is now one of the major causes of blindness. Recent reports have shown that retinal pigment epithelial cell (RPEC) damage plays an essential part in DR development and progression. This work intended to explore the potential effects of Gigantol on high glucose (HG)-stimulated RPEC damage and identify potential mechanisms. METHODS: Cell viability, cell damage, and cell apoptosis were evaluated by CCK-8, lactate dehydrogenase (LDH) and flow cytometry assays. The levels of oxidative stress biomarkers and pro-inflammatory cytokines were assessed using corresponding commercial kits and ELISA. Additionally, the levels of MTDH and NF-kB signaling pathway-related proteins were detected by western blotting. RESULTS: Gigantol dose-dependently enhanced cell viability and decreased apoptosis in HG-challenged ARPE-19 cells. Also, Gigantol notably relieved oxidative stress and inflammatory responses in ARPE-19 cells under HG conditions. Gigantol dose-dependently suppressed MTDH expression. In addition, MTDH restoration partially counteracted the protective effects of Gigantol on ARPE-19 cells subject to HG treatment. Mechanically, Gigantol inactivated the NF-kB signaling pathway, which was partly restored after MTDH overexpression. CONCLUSION: Our findings suggested that Gigantol protected against HG-induced RPEC damage by inactivating the NF-kB signaling via MTDH inhibition, offering a potent therapeutic drug for DR treatment.

miRNA-559 and MTDH as possible diagnostic markers of psoriasis: Role of PTEN/AKT/FOXO pathway in disease pathogenesis.

Psoriasis is a persistent, inflammatory, autoimmune skin disorder which can be elicited by genetic and environmental factors. Several microRNAs (miRNAs) that are abnormally expressed in psoriasis have emerged as an interesting candidate in psoriasis pathogenesis. However, the expression profile and function of miRNA-559, and its direct target metadherin (MTDH), in psoriasis need to be further illuminated. This study intended to assess miRNA-559 and MTDH levels in skin and sera of psoriatic patients and to investigate their clinical significance in an attempt for developing novel distinct tools for early diagnosis of psoriasis. Moreover, this study aimed at exploring participation of miRNA-559 in regulating MTDH/PTEN/AKT pathway in psoriasis. Expression levels of miRNA-559, AKT, FOXO1 and PTEN were measured by real-time qRT-PCR, whereas MTDH and p27 levels were assessed by ELISA in lesional, non-lesional tissues and serum of 20 psoriatic patients and 20 matching controls. Correlation study was conducted between different parameters. The diagnostic performance of miRNA-559 and MTDH in psoriasis was estimated by receiver operating characteristic (ROC) curve analysis. Expression of miRNA-559 in psoriatic patients was significantly downregulated in both lesional tissues and serum as compared to controls. Conversely, MTDH protein level showed significant increase in both tissues and serum of psoriatic patients and was inversely correlated with miRNA-559 level. Meanwhile, levels of PTEN, AKT and FOXO1 were dramatically changed in psoriatic patients compared to controls. Furthermore, serum miRNA-559 and MTDH displayed comparable diagnostic accuracy in discriminating psoriatic patients from controls. Yet, miRNA-559 demonstrated superior diagnostic performance than MTDH in psoriasis diagnosis. Together, the current findings provide the first suggestion of a new mechanism by which downregulation of miRNA-559 might induce proliferation in psoriasis through modulating PTEN/AKT/FOXO1 pathway by positive regulation of MTDH. Thus, miRNA-559 and MTDH might be proposed as promising diagnostic biomarkers of psoriasis.

Linc00239 Promotes Colorectal Cancer Development via MicroRNA-182-5p/Metadherin Axis.

Long non-coding RNAs (lncRNAs) are associated with colorectal cancer (CRC); however, CRC-related linc00239 functions have not been fully elucidated. Prognostic analysis of patients with CRC with linc00239 overexpression was performed using data from The Cancer Genome Atlas database. Cell Counting Kit-8 and Transwell were used to determine linc00239 functions for CRC cells. The lncRNA-miRNA-mRNA interaction network was used to screen target miRNAs and mRNAs regulated by linc00239. Quantitative real-time polymerase chain reaction and western blotting were used to confirm the miRNA and mRNA expression. Furthermore, a miRNA inhibitor was transfected into CRC cells, and cell function was evaluated. Results indicated a high linc00239 expression in the tumor tissue of patients with CRC. Transfection of linc00239 siRNA into SW480 and LOVO cells decreased cell proliferation, cell migration, and invasion. MiR-182-5p/metadherin (MTDH) axis is a downstream pathway of linc00239. MTDH expression, the activity of cell proliferation, migration, and invasion, which were suppressed by linc00239 siRNA, were partially attenuated when linc00239 siRNA and miR-182-5p inhibitor were co-transfected into the CRC cells. Furthermore, miR-182-5p expression was decreased and MTDH expression was promoted in CRC tissues. Altogether, linc00239 may promote CRC development through the miR-182-5p/MTDH axis.

Leishmania Regulated MTDH Expression to Suppress Dendritic Cells.

This study aimed to investigate the correlation between Leishmania infection and dendritic cell infiltration and explore the underlying molecular mechanism how Leishmania infection regulates dendritic cell infiltration. Three datasets, GSE63931, GSE80008 and GSE77528 were combined and their batch effects were removed by Combat function in sva R package. Immune cell infiltrations were estimated using the Microenvironment Cell Populations-counter (MCP-counter) R package. Statistical results were verified by Student's t test. The differential expression of metadherin (MTDH) was identified by Limma R package. The correlation between MTDH expression and dendritic cell infiltration was estimated by Pearson's product moment correlation coefficient. GDS5086 was used to explore MTDH expression pattern in dendritic cells infected with Leishmania. Compared with normal samples, 5 types of immune cells showed differential infiltration in leishmaniasis samples, including T cells, CD8+ T cells, dendritic cells, cytotoxic lymphocytes and B lineage cells. Among these, only DCs were significantly suppressed in leishmaniasis samples. Notably, MTDH expression was differential between leishmaniasis and normal samples. There was a significant correlation between MTDH expression and dendritic cell infiltration. In conclusion, these results demonstrate that Leishmania infection leads to the downregulation of MTDH expression and the suppression of dendritic cell infiltration.

Long non-coding RNA NORAD/miR-224-3p/MTDH axis contributes to CDDP resistance of esophageal squamous cell carcinoma by promoting nuclear accumulation of ß-catenin.

BACKGROUND: Cis-diamminedichloro-platinum (CDDP)-based chemotherapy regimens are the most predominant treatment strategies for patients with esophageal squamous cell carcinoma (ESCC). Dysregulated long non-coding RNAs (lncRNAs) contribute to CDDP resistance, which results in treatment failure in ESCC patients. However, the majority of lncRNAs involved in CDDP resistance in ESCC remain to be elucidated. METHODS: The public Gene Expression Omnibus (GEO) dataset GSE45670 was analysed to reveal potential lncRNAs involved in CDDP resistance of ESCC. Candidate upregulated lncRNAs were detected in ESCC specimens by qRT-PCR to identify crucial lncRNAs. Non-coding RNA activated by DNA damage (NORAD) was selected for further study. Kaplan-Meier analysis and a COX proportional regression model were performed to analyse the potential of NORAD for predicting prognosis of ESCC patients. The role of NORAD in CDDP resistance were determined by conducting gain and loss-of-function experiments in vitro. Fluorescence in situ hybridization (FISH) was performed to determine the subcellular location of NORAD in ESCC cells. A public GEO dataset and bioinformatic algorithms were used to predict the microRNAs (miRNAs) that might be latently sponged by NORAD. qRT-PCR was conducted to verify the expression of candidate miRNAs. Luciferase reporter and Argonaute-2 (Ago2)-RNA immunoprecipitation (RIP) assays were conducted to evaluate the interaction between NORAD and candidate miRNAs. A miRNA rescue experiment was performed to authenticate the NORAD regulatory axis and its effects on CDDP resistance in ESCC cells. Western blotting was conducted to confirm the precise downstream signalling pathway of NORAD. A xenograft mouse model was established to reveal the effect of NORAD on CDDP resistance in vivo. RESULTS: The expression of NORAD was higher in CDDP-resistant ESCC tissues and cells than in CDDP-sensitive tissues and cells. NORAD expression was negatively correlated with the postoperative prognosis of ESCC patients who underwent CDDP-based chemotherapy. NORAD knockdown partially arrested CDDP resistance of ESCC cells. FISH showed that NORAD was located in the cytoplasm in ESCC cells. Furthermore, overlapping results from bioinformatic algorithms analyses and qRT-PCR showed that NORAD could sponge miR-224-3p in ESCC cells. Ago2-RIP demonstrated that NORAD and miR-224-3p occupied the same Ago2 to form an RNA-induced silencing complex (RISC) and subsequently regulated the expression of metadherin (MTDH) in ESCC cells. The NORAD/miR-224-3p/MTDH axis promoted CDDP resistance and progression in ESCC cells by promoting nuclear accumulation of ß-catenin in vitro and in vivo. CONCLUSIONS: NORAD upregulates MTDH to promote CDDP resistance and progression in ESCC by sponging miR-224-3p. Our results highlight the potential of NORAD as a therapeutic target in ESCC patients receiving CDDP-based chemotherapy.

Metadherin (MTDH) overexpression significantly correlates with advanced tumor grade and stages among colorectal cancer patients.

BACKGROUND: Colorectal cancer is the 4th leading cause of cancer related deaths affecting both men and women worldwide. In the present study, any probable role of MTDH mRNA expression in CRC tumorigenesis was explored using both discovery and validation cohorts. METHODS AND RESULTS: After prior ethical and biosafety approvals, tumor tissue samples along with their adjacent controls were collected for this study from Pakistani patients diagnosed with colorectal cancer. RNA was isolated using Trizol reagent, followed by cDNA synthesis. Transcript analysis of MTDH was performed by using qPCR. Moreover, genome-wide expression of MTDH was also determined through micro-array data analysis using BRB-array tools software. MTDH expression was significantly high in tumor tissue samples (p < 0.05) compared to their respective controls. Likewise, results of microarray analysis also revealed overamplification of MTDH in tumor samples as compared to controls. Expression of MTDH was also found to be positively correlated with KI-67 index (p < 0.05) and were observed to be significantly upregulated in advance tumor grade (p < 0.05) and stage (p < 0.05). However, no association of MTDH overexpression with age and gender could be established. CONCLUSION: Hence, it can be concluded that MTDH is a core element that plays a pivotal role in colorectal tumorigenesis irrespective of patient's age and gender. Molecular insight into the tumor microenvironment revealed MTDH as a niche, representing distinctive framework for cancer progression, thus, making it an innovative target strategy for colorectal cancer treatment.

Transcriptional Repression of Raf Kinase Inhibitory Protein Gene by Metadherin during Cancer Progression.

Raf kinase inhibitory protein (RKIP), also known as a phosphatidylethanolamine-binding protein 1 (PEBP1), functions as a tumor suppressor and regulates several signaling pathways, including ERK and NF-κκB. RKIP is severely downregulated in human malignant cancers, indicating a functional association with cancer metastasis and poor prognosis. The transcription regulation of RKIP gene in human cancers is not well understood. In this study, we suggested a possible transcription mechanism for the regulation of RKIP in human cancer cells. We found that Metadherin (MTDH) significantly repressed the transcriptional activity of RKIP gene. An analysis of publicly available datasets showed that the knockdown of MTDH in breast and endometrial cancer cell lines induced the expression RKIP. In addition, the results obtained from qRT-PCR and ChIP analyses showed that MTDH considerably inhibited RKIP expression. In addition, the RKIP transcript levels in MTDH-knockdown or MTDH-overexpressing MCF-7 cells were likely correlated to the protein levels, suggesting that MTDH regulates RKIP expression. In conclusion, we suggest that MTDH is a novel factor that controls the RKIP transcription, which is essential for cancer progression.

The long non-coding RNA HCG18 promotes the growth and invasion of colorectal cancer cells through sponging miR-1271 and upregulating MTDH/Wnt/ß-catenin.

Long non-coding RNAs (lncRNAs) have recently emerged as key regulators of the occurrence and progression of various human cancers, including colorectal cancer. However, the regulatory mechanism of lncRNAs in the tumorigenesis of colorectal cancer remains poorly understood. In this study, we aimed to elucidate the potential role of lncRNA HCG18 in colorectal cancer. Herein, we found that HCG18 expression was significantly upregulated in colorectal cancer tissues and cell lines. Knockdown of HCG18 significantly inhibited the growth and invasion of colorectal cancer cells, while its overexpression had the opposite effect. Moreover, HCG18 was identified as a sponge of miR-1271. Our results showed that knockdown of HCG18 markedly upregulated miR-1271 expression in colorectal cancer cells. Notably, HCG18 expression was inversely correlated with miR-1271 expression in colorectal cancer specimens. Further investigation revealed that HCG18 contributed to the enhancement of MTDH/Wnt/ß-catenin signalling in colorectal cancer cells. The antitumour effect of HCG18 inhibition was significantly reversed by miR-1271 inhibition or MTDH overexpression. Overall, the results of our study demonstrate that HCG18 exerts a potential oncogenic function in colorectal cancer by enhancing MTDH/Wnt/ß-catenin signalling via sponging of miR-1271, highlighting the importance of HCG18/miR-1271/ MTDH/Wnt/ß-catenin signalling in the progression of colorectal cancer.

MiR-128 suppresses metastatic capacity by targeting metadherin in breast cancer cells.

BACKGROUND: Breast cancer, the most common cancer in women worldwide, causes the vast majority of cancer-related deaths. Undoubtedly, tumor metastasis and recurrence are responsible for more than 90 percent of these deaths. MicroRNAs are endogenous noncoding RNAs that have been integrated into almost all the physiological and pathological processes, including metastasis. In the present study, the role of miR-128 in breast cancer was investigated. RESULTS: Compared to the corresponding adjacent normal tissue, the expression of miR-128 was significantly suppressed in human breast cancer specimens. More importantly, its expression level was reversely correlated to histological grade of the cancer. Ectopic expression of miR-128 in the aggressive breast cancer cell line MDA-MB-231 could inhibit cell motility and invasive capacity remarkably. Afterwards, Metadherin (MTDH), also known as AEG-1 (Astrocyte Elevated Gene 1) and Lyric that implicated in various aspects of cancer progression and metastasis, was further identified as a direct target gene of miR-128 and its expression level was up-regulated in clinical samples as expected. Moreover, knockdown of MTDH in MDA-MB-231 cells obviously impaired the migration and invasion capabilities, whereas re-expression of MTDH abrogated the suppressive effect caused by miR-128. CONCLUSIONS: Overall, these findings demonstrate that miR-128 could serve as a novel biomarker for breast cancer metastasis and a potent target for treatment in the future.

CCL18 promotes the metastasis of squamous cell carcinoma of the head and neck through MTDH-NF-κB signalling pathway.

Metastasis is one of the primary causes for high mortality in patients with squamous cell carcinoma of the head and neck (SCCHN). Our previous study showed that chemokine (C-C motif) ligand 18 (CCL18), derived from tumour-associated macrophages (TAMs), regulates SCCHN metastasis by promoting epithelial-mesenchymal transition (EMT) and preserving stemness. However, the underlying mechanism needs to be further investigation. Interestingly, metadherin (MTDH) expression was induced when SCCHN cells were stimulated with recombinant CCL18 protein in this study. Suppressing MTDH expression reversed CCL18-induced migration, invasion and EMT in SCCHN cells. Furthermore, the NF-κB signalling pathway was involved in the MTDH knock-down cells with CCL18 stimulation. We performed ELISA to evaluate the CCL18 levels in the serums of 132 treatment-naive SCCHN patients, 25 patients with precancerous lesion and 32 healthy donors. Our results demonstrated that serum CCL18 levels were significantly higher in SCCHN patients than patients with precancerous lesion and healthy individuals. CCL18 levels were found to be significantly correlated with tumour classification, clinical stage, lymph node metastasis and histological grade in SCCHN patients. Thus, our findings suggest that CCL18 may serve as a potential biomarker for diagnosis of SCCHN and promote SCCHN invasion, migration and EMT by MTDH-NF-κB signalling pathway.

MTDH/AEG-1 downregulation using pristimerin-loaded nanoparticles inhibits Fanconi anemia proteins and increases sensitivity to platinum-based chemotherapy.

OBJECTIVE: Platinum compounds have been widely used as a primary treatment for many types of cancer. However, resistance is the major cause of therapeutic failure for patients with metastatic or recurrent disease, thus highlighting the need to identify novel factors driving resistance to Platinum compounds. Metadherin (MTDH, also known as AEG-1 and LYRIC), located in a frequently amplified region of chromosome 8, has been consistently associated with resistance to chemotherapeutic agents, though the precise mechanisms remain incompletely defined. METHODS: The mRNA of FANCD2 and FANCI was pulled down by RNA-binding protein immunoprecipitation. Pristimerin-loaded nanoparticles were prepared using the nanoprecipitation method. Immunocompromised mice bearing patient-derived xenograft tumors were treated with pristimerin-loaded nanoparticles, cisplatin and a combination of the two. RESULTS: MTDH, through its recently discovered role as an RNA binding protein, regulates expression of FANCD2 and FANCI, two components of the Fanconi anemia complementation group (FA) that play critical roles in interstrand crosslink damage induced by platinum compounds. Pristimerin, a quinonemethide triterpenoid extract from members of the Celastraceae family used to treat inflammation in traditional Chinese medicine, significantly decreased MTDH, FANCD2 and FANCI levels in cancer cells, thereby restoring sensitivity to platinum-based chemotherapy. Using a patient-derived xenograft model of endometrial cancer, we discovered that treatment with pristimerin in a novel nanoparticle formulation markedly inhibited tumor growth when combined with cisplatin. CONCLUSIONS: MTDH is involved in post-transcriptional regulation of FANCD2 and FANCI. Pristimerin can increase sensitivity to platinum-based agents in tumors with MTDH overexpression by inhibiting the FA pathway.

Activation of EMT in colorectal cancer by MTDH/NF-κB p65 pathway.

Epithelial-mesenchymal transition (EMT) leads to tumor dissemination and metastasis. Metadherin (MTDH) is an oncogene that plays an important role in metastasis regulation. This study tries to investigate the effect of MTDH gene up-regulation on the activation of EMT in colorectal cancer (CRC) cells and identify the role of NF-κB p65. The CaCO2 cells were divided into three groups: one control group of cultured CaCO2 cells (C1), and two groups of CaCO2 cells co-transfected using human MTDH expression plasmid with either siRNA targeting human NF-κB p65 or its negative control (C2 and C3 respectively). The gene modification was confirmed by qPCR and the effect of gene modification on CRC aggravation was studied. MTDH up-regulation significantly promoted CRC cell proliferation, activated anaerobic respiration (glucose consumption and lactate production), and increased gene expression of multidrug resistance gene (MDR1), Snail transcription factor and NF-κB p65, but decreased the gene expression of E-cadherin. Moreover, MTDH up-regulation led to a significant increase in the acquisition of surface markers of CRC stem cells. Interference with NF-κB p65 gene expression reversed the action of MTDH gene up-regulation on MDR1 and E-cadherin gene expression and anaerobic respiration. Moreover, NF-κB p65 interference significantly decreased MTDH-induced cell proliferation and acquisition of surface markers of CRC stem cells but didn't affect the Snail transcription factor. MTDH-dependent EMT in CRC is activated via NF-κB p65 and is mediated by up-regulation of Snail. These results identify a pathway by which MTDH regulates NF-κB p65 induced EMT during CRC cell metastasis.

Efficient and tumor-specific knockdown of MTDH gene attenuates paclitaxel resistance of breast cancer cells both in vivo and in vitro.

BACKGROUND: Drug resistance of paclitaxel (TAX), the first-line chemotherapy drug for breast cancer, was reported to develop in 90% of patients with breast cancer, especially metastatic breast cancer. Investigating the mechanism of TAX resistance of breast cancer cells and developing the strategy improving its therapeutic efficiency are crucial to breast cancer cure. METHODS AND RESULTS: We here report an elegant nanoparticle (NP)-based technique that realizes efficient breast cancer treatment of TAX. Using lentiviral vector-mediated gene knockdown, we first demonstrated that TAX therapeutic efficiency was closely correlated with metadherin (MTDH) gene expression in breast cancer cell lines. This finding was also supported by efficacy of TAX treatment in breast cancer patients from our clinical studies. Specifically, TAX treatment became more effective when MTDH expression was decreased in MCF-7 cancer cells by the blocking nuclear factor-kappa B (NF-κB) pathway. Based on these findings, we subsequently synthesized a polymeric NP that could co-deliver MTDH-small interfering RNA (MTDH-siRNA) and TAX into the breast cancer tumors in tumor-bearing mice. The NPs were composed of a cationic copolymer, which wrapped TAX in the inside and adsorbed the negatively charged siRNA on their surface with high drug-loading efficiency and good stability. CONCLUSIONS: NP-based co-delivery approach can effectively knock down the MTDH gene both in vitro and in vivo, which dramatically inhibits breast tumor growth, achieving effective TAX chemotherapy treatment without overt side effects. This study provides a potential therapeutic strategy for the treatment of a wide range of solid tumors highly expressing MTDH.

Autophagy Facilitates Metadherin-Induced Chemotherapy Resistance Through the AMPK/ATG5 Pathway in Gastric Cancer.

BACKGROUND/AIMS: Metadherin (MTDH) is overexpressed in some malignancies and enhances drug resistance; however, its role in gastric cancer (GC) and the underlying mechanisms remain largely unexplored. Here, we explore the mechanism by which MTDH induces drug resistance in GC. METHODS: We analysed the level of MTDH in GC and adjacent normal gastric mucosal tissues by real-time quantitative PCR (q-PCR). We also analysed the level of autophagy by western blot analysis, confocal microscopy, and transmission electron microscopy after MTDH knockdown and overexpression, and examined fluorouracil (5-FU) resistance by Cell Counting Kit-8 at the same time. Finally, GC patient-derived xenograft tumours were used to demonstrate 5-FU resistance. An AMPK pathway inhibitor was applied to determine the molecular mechanisms of autophagy. RESULTS: MTDH expression was significantly increased in the GC specimens compared with that in the adjacent normal gastric mucosal tissues. Further study showed a positive correlation between the expression level of MTDH and 5-FU resistance. MTDH overexpression in MKN45 cells increased the levels of P-glycoprotein (P-gp) and promoted 5-FU resistance, while inhibition of MTDH showed the opposite result. The simultaneous inhibition of autophagy and overexpression of MTDH decreased the levels of P-gp and inhibited 5-FU resistance. Moreover, MTDH induced AMPK phosphorylation, regulated ATG5 expression, and finally influenced autophagy, suggesting that MTDH may activate autophagy via the AMPK/ATG5 signalling pathway. Our findings reveal a unique mechanism by which MTDH promotes GC chemoresistance and show that MTDH is a potential target for improved chemotherapeutic sensitivity and GC patient survival. CONCLUSIONS: MTDH-stimulated cancer resistance to 5-FU may be mediated through autophagy activated by the AMPK/ATG5 pathway in GC.

miR-145 and miR-497 suppress TGF-ß-induced epithelial-mesenchymal transition of non-small cell lung cancer by targeting MTDH.

BACKGROUND: MicroRNAs (miRNAs) have been reported to play crucial roles in multiple cancers including non-small cell lung cancer (NSCLC). Here, we investigated the role of miR-145 and miR-497 in TGF-ß-induced epithelial-mesenchymal transition (EMT) process of NSCLC. METHODS: We performed quantitative real time PCR (qRT-PCR) to detect the expression level of miR-145 and miR-497 in NSCLC cell lines. Then in the presence/absence of TGF-ß, we transfected miRNA mimics or inhibitor into A549 and H1299 cells and investigated the role of miR-145 and miR-497 in cell migration and invasion using transwell and wound-healing assay. The regulation role of miR-145 and miR-497 on Metadherin (MTDH) was determined by luciferase assay. The expression level of MTDH and EMT markers E-cadherin and vimentin were detected on mRNA and protein level. RESULTS: In our study, our results showed that miR-145 and miR-497 were downregulated in NSCLC cell lines. Overexpression of miR-145 and miR-497 inhibited TGF-ß-induced EMT and suppressed cancer cell migration and invasion, while the opposite results were observed in cells transfected with miR-145 or miR-497 inhibitor. Moreover, the luciferase assay confirmed that miR-145 and miR-497 attenuated MTDH expression by directly binding 3'-UTR of MTDH mRNA and exert the tumor-suppression role. CONCLUSIONS: Overall, we demonstrated that miR-145 and miR-497 functioned as EMT-suppressor in NSCLC by targeting MTDH, provided new evidence that miR-145 and miR-497 as potential therapeutic targets.

MiR-1297 suppresses pancreatic cancer cell proliferation and metastasis by targeting MTDH.

Dysregulation of miR-1297 has been detected in various human cancers, and miR-1297 can function as either an oncogene or tumor suppressor. However, the role of miR-1297 in pancreatic adenocarcinoma has not been previously reported. Here, we investigated miR-1297 expression in pancreatic cancer and the role it plays in the development and metastasis of pancreatic adenocarcinoma. In the present study, MiR-1297 and metadherin (MTDH) expression in pancreatic cancer tissue was detected using quantitative real-time PCR (qRT-PCR) and western blot methods. The CCK-8 assay and EdU incorporation assay were used to analyze the impact of miR-1297 and MTDH on cell proliferation. Flow cytometric and Hoechst 33342 staining methods were used to explore how miR-1297 and MTDH affect cell apoptosis. The Transwell assay and scratch wound healing assay were used to analyze cell migration and invasion capabilities. The dual-luciferase assay was used to confirm that miR-1297 targets MTDH. Here, we found that miR-1297 expression was decreased in pancreatic adenocarcinoma tissues, while MTDH expression was increased in those tissues. Furthermore, western blot and dual-luciferase assay results confirmed that MTDH was a direct target of miR-1297. Additionally, overexpression of miR-1297 or knockdown of MTDH suppressed BxPC-3 and PANC-1 cell proliferation, and upregulation of miR-1297 or suppression of MTDH promoted BxPC-3 and PANC-1 cell apoptosis. Finally, BxPC-3 and PANC-1 cell migration and invasion abilities were suppressed by either overexpression of miR-1297 or downregulation of MTHD. In conclusion, our results suggest that miR-1297 inhibits the growth and metastasis of pancreatic adenocarcinoma by downregulating MTDH expression, and the miR-1297/MTDH pathway is a potential target for treating pancreatic adenocarcinoma.

MicroRNA-1271 suppresses the proliferation and invasion of colorectal cancer cells by regulating metadherin/Wnt signaling.

Recent studies have reported an important role for microRNA-1271 (miR-1271) in tumorigenesis. However, the role of miR-1271 in colorectal cancer remains unknown. Here, we found that miR-1271 was significantly decreased in colorectal cancer tissues and cell lines. Overexpression of miR-1271 inhibited cell proliferation, colony formation, cell invasion, and induced cell cycle arrest in colorectal cancer cells. Metadherin (MTDH) was identified as a target gene of miR-1271. Moreover, miR-1271 negatively regulated MTDH expression in colorectal cancer cells and reversely correlated with MTDH expression in colorectal cancer specimens. Additionally, miR-1271 also regulated the activation of Wnt signaling in colorectal cancer cells. The restoration of MTDH expression significantly reversed the antitumor effect of miR-1271 in colorectal cancer cells. These findings indicate an important role for miR-1271/MTDH in the tumorigenesis of colorectal cancer, and suggest that miR-1271 may be a novel therapeutic target for colorectal cancer.

The FBXW7 tumor suppressor inhibits breast cancer proliferation and promotes apoptosis by targeting MTDH for degradation.

Metadherin (MTDH) is an oncoprotein and is expressed at high levels in a wide variety of human carcinomas, which represents an important genetic determinant and regulates multiple events in tumorigenesis. MTDH promotes breast cancer cell proliferation and tumorigenesis through the activation of numerous signaling pathways. Currently, the mecha- nism regulating MTDH expression is poorly understood. Here we identified that FBXW7, a component of E3 ubiquitin ligase, targets MTDH for ubiquitin-mediated degradation. Forced overexpression of FBXW7 could decrease the level of MTDH protein, and inhibition of endogenous FBXW7 expression remarkably increases the MTDH protein abundance. More importantly, overexpression of FBXW7 could lead to proliferation arrest and apoptosis in breast cancer cells through targeting MTDH degradation. These data suggest that FBXW7, a tumor suppressor, inhibits breast cancer cell prolifera- tion and promotes apoptosis at least partially through targeting MTDH for proteolysis. This new regulatory mechanism of MTDH by FBXW7 represents a new pathway for malignant phenotype turnover in human breast cancer.