The epithelial-mesenchymal transition (EMT) is a process in which polarized epithelial cells are converted into motile mesenchymal cells. During cancer development, EMT is conducive to tumor dissemination and metastatic spread. While overexpression of metadherin (MTDH) in breast cancer cell lines and tissues has been found to be associated with aggressive tumor behavior, its precise role in invasion and metastasis is largely unknown. Here we report that MTDH overexpression could significantly enhance the invasion and migration of breast cancer cells by inducing EMT. Metadherin overexpression led to upregulation of mesenchymal marker fibronectin, downregulation of epithelial marker E-cadherin, and the nuclear accumulation of beta-catenin. Also, transcription factors Snail and Slug were upregulated in breast cancer cells overexpressing MTDH. Overexpression of MTDH enhanced the invasiveness and migration ability of breast cancer cells in vitro. In addition, overexpression of MTDH led to increased acquisition of CD44(+) /CD24(-/low) markers that are characteristic of breast cancer stem cells. We also showed that NF-kappa was involved in the expression of EMT-related markers. Taken together, our results suggest that MTDH could promote EMT in breast cancer cells in driving the progression of their aggressive behavior.

Migraine is a common neurological disorder with a genetically complex background. This paper describes a meta-analysis of genome-wide association (GWA) studies on migraine, performed by the Dutch-Icelandic migraine genetics (DICE) consortium, which brings together six population-based European migraine cohorts with a total sample size of 10,980 individuals (2446 cases and 8534 controls). A total of 32 SNPs showed marginal evidence for association at a P-value<10(-5). The best result was obtained for SNP rs9908234, which had a P-value of 8.00 × 10(-8). This top SNP is located in the nerve growth factor receptor (NGFR) gene. However, this SNP did not replicate in three cohorts from the Netherlands and Australia. Of the other 31 SNPs, 18 SNPs were tested in two replication cohorts, but none replicated. In addition, we explored previously identified candidate genes in the meta-analysis data set. This revealed a modest gene-based significant association between migraine and the metadherin (MTDH) gene, previously identified in the first clinic-based GWA study (GWAS) for migraine (Bonferroni-corrected gene-based P-value=0.026). This finding is consistent with the involvement of the glutamate pathway in migraine. Additional research is necessary to further confirm the involvement of glutamate.

In this study, we report the experience of the only reference clinical next-generation sequencing lab in Saudi Arabia with the first 1000 families who span a wide-range of suspected Mendelian phenotypes. A total of 1019 tests were performed in the period of March 2016-December 2016 comprising 972 solo (index only), 14 duo (parents or affected siblings only), and 33 trio (index and parents). Multigene panels accounted for 672 tests, while whole exome sequencing (WES) represented the remaining 347 tests. Pathogenic or likely pathogenic variants that explain the clinical indications were identified in 34% (27% in panels and 43% in exomes), spanning 279 genes and including 165 novel variants. While recessive mutations dominated the landscape of solved cases (71% of mutations, and 97% of which are homozygous), a substantial minority (27%) were solved on the basis of dominant mutations. The highly consanguineous nature of the study population also facilitated homozygosity for many private mutations (only 32.5% of the recessive mutations are founder), as well as the first instances of recessive inheritance of previously assumed strictly dominant disorders (involving ITPR1, VAMP1, MCTP2, and TBP). Surprisingly, however, dual molecular diagnosis was only observed in 1.5% of cases. Finally, we have encountered candidate variants in 75 genes (ABHD6, ACY3, ADGRB2, ADGRG7, AGTPBP1, AHNAK2, AKAP6, ASB3, ATXN1L, C17orf62, CABP1, CCDC186, CCP110, CLSTN2, CNTN3, CNTN5, CTNNA2, CWC22, DMAP1, DMKN, DMXL1, DSCAM, DVL2, ECI1, EP400, EPB41L5, FBXL22, GAP43, GEMIN7, GIT1, GRIK4, GRSF1, GTRP1, HID1, IFNL1, KCNC4, LRRC52, MAP7D3, MCTP2, MED26, MPP7, MRPS35, MTDH, MTMR9, NECAP2, NPAT, NRAP, PAX7, PCNX, PLCH2, PLEKHF1, PTPN12, QKI, RILPL2, RIMKLA, RIMS2, RNF213, ROBO1, SEC16A, SIAH1, SIRT2, SLAIN2, SLC22A20, SMDT1, SRRT, SSTR1, ST20, SYT9, TSPAN6, UBR4, VAMP4, VPS36, WDR59, WDYHV1, and WHSC1) not previously linked to human phenotypes and these are presented to accelerate post-publication matchmaking. Two of these genes were independently mutated in more than one family with similar phenotypes, which substantiates their link to human disease (AKAP6 in intellectual disability and UBR4 in early dementia). If the novel candidate disease genes in this cohort are independently confirmed, the yield of WES will have increased to 83%, which suggests that most "negative" clinical exome tests are unsolved due to interpretation rather than technical limitations.

BACKGROUND

Breast cancer is the most prevalent cancer in women worldwide and metastatic breast cancer has very poor prognosis. Inflammation has been implicated in migration and metastasis of breast cancer, although the exact molecular mechanism remains elusive.

RESULTS

We show that the pro-inflammatory endotoxin Lipopolysaccharide (LPS) upregulates the expression of Metadherin (MTDH), a recently identified oncogene, in a number of breast cancer lines. Stable knockdown of MTDH by shRNA in human breast MDA-MB-231 cells abolishes LPS-induced cell migration and invasion as determined by several in vitro assays. In addition, knockdown of MTDH diminishes Nuclear Factor-kappa B (NF-κB) activation by LPS and inhibited LPS-induced IL-8 and MMP-9 production.

CONCLUSIONS

These results strongly suggest that MTDH is a pivotal molecule in inflammation-mediated tumor metastasis. Since NF-κB, IL-8 and MMP-9 play roles in LPS-induced invasion or metastasis, the mechanism of MTDH-promoted invasion and metastasis may be through the activation of NF-κB, IL-8 and MMP-9, also suggesting a role of MTDH in regulating both inflammatory responses and inflammation-associated tumor invasion. These findings indicate that MTDH is involved in inflammation-induced tumor progression, and support that MTDH targeting therapy may hold promising prospects in treating breast cancer.

The oncogene astrocyte elevated gene-1 (AEG-1; MTDH) is highly expressed in glioblastoma multiforme (GBM) and many other types of cancer, where it activates multiple signaling pathways that drive proliferation, invasion, angiogenesis, chemoresistance, radioresistance, and metastasis. AEG-1 activates the Akt signaling pathway and Akt and c-Myc are positive regulators of AEG-1 transcription, generating a positive feedback loop between AEG-1 and Akt in regulating tumorigenesis. Here, we describe in GBM cells a direct interaction between an internal domain of AEG-1 and the PH domain of Akt2, a major driver in GBM. Expression and interaction of AEG-1 and Akt2 are elevated in GBM and contribute to tumor cell survival, proliferation, and invasion. Clinically, in silico gene expression and immunohistochemical analyses of patient specimens showed that AEG-1 and Akt2 expression correlated with GBM progression and reduced patient survival. AEG-1-Akt2 interaction prolonged stabilization of Akt2 phosphorylation at S474, regulating downstream signaling cascades that enable cell proliferation and survival. Disrupting AEG-1-Akt2 interaction by competitive binding of the Akt2-PH domain led to reduced cell viability and invasion. When combined with AEG-1 silencing, conditional expression of Akt2-PH markedly increased survival in an orthotopic mouse model of human GBM. Our study uncovers a novel molecular mechanism by which AEG-1 augments glioma progression and offers a rationale to block AEG-1-Akt2 signaling function as a novel GBM treatment.

Our recent study suggested that metadherin (MTDH) is overexpressed in laryngeal squamous cell carcinoma. Here, we further investigated its role in promoting metastasis of squamous cell carcinoma of the head and neck (SCCHN). An immunohistochemistry analysis demonstrated that MTDH is elevated and positively correlated with metastasis in 189 primary SCCHN tissues. In vitro experiments demonstrated that MTDH overexpression enhanced the migratory and invasive ability of SCCHN cells. Moreover, MTDH induced epithelial-mesenchymal transition (EMT) by both regulating morphological changes and mediating the expression of the biomolecular makers E-cadherin and vimentin. In addition, MTDH mediated AKT activation, and all of the above effects were nearly completely blocked by the inhibition of AKT. Our results suggested that MTDH might promote the metastasis of SCCHN through AKT signalling pathway mediated-EMT.

MicroRNAs (miRNAs) play critical roles in tumorigenesis by modulating the expression of target gene mRNAs. However, their role in cell signaling is not well defined. In this study, we identified miR-30d as a downstream effector of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway in renal cell carcinoma (RCC) cells. We show that Akt inhibition transcriptionally up-regulates miR-30d expression through activation of the transcription factor forkhead box O (FOXO) 3A. Functional analysis revealed that miR-30d overexpression suppresses cell proliferation and induces apoptosis in RCC cells, suggesting that miR-30d acts as a tumor suppressor. In searching for downstream targets of miR-30d, we found that miR-30d post-transcriptionally suppresses expression of the oncoprotein metadherin (MTDH) by destabilizing its mRNA. Furthermore, we found that FOXO down-regulates MTDH expression through up-regulating expression of miR-30d. Thus, our findings reveal a new Akt/FOXO/miR-30d/MTDH signaling transduction pathway and identify miR-30d as a tumor suppressor, providing a new potential target for the treatment of RCC.

Gene amplification is an important mechanism for oncogene activation, a crucial step in carcinogenesis. Compared to female breast cancer, little is known on the genetic makeup of male breast cancer, because large series are lacking. Copy number changes of 21 breast cancer related genes were studied in 110 male breast cancers using multiplex ligation-dependent probe amplification. A ratio of >1.3 was regarded indicative for gene copy number gain and a ratio >2.0 for gene amplification. Data were correlated with clinicopathological features, prognosis and 17 genes were compared with a group of female breast cancers. Gene copy number gain of CCND1, TRAF4, CDC6 and MTDH was seen in >40 % of the male breast cancer cases, with also frequent amplification. The number of genes with copy number gain and several single genes were associated with high grade, but only CCND1 amplification was an independent predictor of adverse survival in Cox regression (p = 0.015; hazard ratio 3.0). In unsupervised hierarchical clustering a distinctive group of male breast cancer with poor prognosis (p = 0.009; hazard ratio 3.4) was identified, characterized by frequent CCND1, MTDH, CDC6, ADAM9, TRAF4 and MYC copy number gain. Compared to female breast cancers, EGFR (p = 0.005) and CCND1 (p = 0.041) copy number gain was more often seen in male breast cancer, while copy number gain of EMSY (p = 0.004) and CPD (p = 0.001) and amplification in general was less frequent. In conclusion, several female breast cancer genes also seem to be important in male breast carcinogenesis. However, there are also clear differences in copy number changes between male and female breast cancers, pointing toward differences in carcinogenesis between male and female breast cancer and emphasizing the importance of identifying biomarkers and therapeutic agents based on research in male breast cancer. In addition CCND1 amplification seems to be an independent prognosticator in male breast cancer.

Chemoresistance and metastasis are the main reasons for the failure of current treatments with sarcoma patients. Novel biomarkers are required to predict metastasis and response to treatment. The oncogene MTDH/AEG1 and the long noncoding RNA (lincRNA) HOTAIR are two novel factors involved in drug resistance and metastasis in various types of solid tumors. However, the correlation between MTDH/AEG-1 and HOTAIR expression with metastasis and drug resistance in sarcoma is unknown.

Expression of MTDH protein or HOTAIR was detected by Western blotting or qRT-PCR, respectively, in primary and metastatic sarcoma patient tissue samples.

High individual or co-expression of MTDH/AEG1 and HOTAIR was observed in three of four primary and six of eight metastatic sarcoma patient tumor samples. High level expression of both of MTDH/AEG1 and HOTAIR in the primary tumor correlated with a likelihood to metastasize. MTDH expression was lower in samples pre-treated with irradiation and/or chemotherapy as compared to those that had not been treated. HOTAIR expression seemed to correlate with the percent necrosis seen in different sarcoma samples.

High levels of both MTDH/AEG-1 and HOTAIR in primary sarcoma are correlated with a high probability of metastasis. By contrast, reduced expression of both MTDH/AEG-1 and HOTAIR is correlated with a good response to treatment in terms of necrosis, suggesting that levels of MTDH and HOTAIR are potential biomarkers for treatment efficacy. Whether we can predict disease progression in sarcoma remains to be seen. Additional study is needed to better define the best clinical application of MTDH/AEG-1 and HOTAIR expression with metastasis and outcome.

Breast cancer is a heterogeneous disease, and triple-negative breast cancer (TNBC) continues to be a serious health problem. The potential involvement of lncRNAs in TNBC progression remains unexplored. Here, we demonstrated that LINC01638 is highly expressed in TNBC tissues and cells. LINC01638 maintains the mesenchymal traits of TNBC cells, including an enriched epithelial-mesenchymal transition (EMT) signature and cancer stem cell-like state. LINC01638 knockdown suppresses tumor proliferation and metastasis both in vitro and in vivo. LINC01638 overexpression predicts a poor outcome of breast cancer patients. Mechanistically, LINC01638 interacts with c-Myc to prevent SPOP-mediated c-Myc ubiquitination and degradation. C-Myc transcriptionally enhances MTDH (metadherin) expression and subsequently activates Twist1 expression to induce EMT. Our findings describe LINC01638-mediated signal transduction and highlight the crucial role of LINC01638 in TNBC progression.

Since its initial identification as a HIV-1-inducible gene in 2002, astrocyte elevated gene-1 (AEG-1), subsequently cloned as metadherin (MTDH) and lysine-rich CEACAM1 coisolated (LYRIC), has emerged over the past 10 years as an important oncogene providing a valuable prognostic marker in patients with various cancers. Recent studies demonstrate that AEG-1/MTDH/LYRIC is a pleiotropic protein that can localize in the cell membrane, cytoplasm, endoplasmic reticulum (ER), nucleus, and nucleolus, and contributes to diverse signaling pathways such as PI3K-AKT, NF-κB, MAPK, and Wnt. In addition to tumorigenesis, this multifunctional protein is implicated in various physiological and pathological processes including development, neurodegeneration, and inflammation. The present review focuses on the discovery of AEG-1/MTDH/LYRIC and conceptualizes areas of future direction for this intriguing gene. We begin by describing how AEG-1, MTDH, and LYRIC were initially identified by different research groups and then discuss AEG-1 structure, functions, localization, and evolution. We conclude with a discussion of the expression profile of AEG-1/MTDH/LYRIC in the context of cancer, neurological disorders, inflammation, and embryogenesis, and discuss how AEG-1/MTDH/LYRIC is regulated. This introductory discussion of AEG-1/MTDH/LYRIC will serve as the basis for the detailed discussions in other chapters of the unique properties of this intriguing molecule.

BACKGROUND

Metadherin (MTDH) plays functional roles in the tumorigenesis and tumor progression of various cancers. This study investigated the associations between MTDH and the clinicopathological features in primary breast carcinomas to clarify the role of MTDH in the phenotypes and prognosis of breast cancer.

METHODS

A total of 195 primary invasive breast cancer samples were evaluated. The MTDH DNA copy number and MTDH mRNA expression were analyzed by quantitative genomic polymerase chain reaction (PCR) and quantitative reverse transcriptase PCR. MTDH protein expression was analyzed by immunohistochemistry.

RESULTS

A positive correlation was found between the expression of MTDH protein and mRNA expression and the MTDH DNA copy number. MTDH overexpression was significantly associated with a high nuclear grade, negative estrogen receptor (ER) and progesterone receptor (PR) expression, high Ki67 index, poor disease-free survival (P = 0.0001), poor distant metastasis-free survival (P = 0.009), and poor overall survival (P = 0.0101). MTDH overexpression showed a particularly negative impact on the prognosis in node-negative patients. A multivariate analysis showed MTDH overexpression to be independently associated with a poor disease-free survival rate [HR 3.45, 95 % confidence interval (CI) 1.69-6.84, P = 0.0010] and a poor distant metastasis-free survival rate (HR 2.39, 95 % CI 1.08-5.01, P = 0.0319).

CONCLUSIONS

MTDH overexpression contributes to an aggressive phenotype, thus leading to a poor prognosis for primary invasive breast cancer.

Long noncoding RNAs participate in the progression and initiation of non-small cell lung cancer (NSCLC), although the mechanism remains unknown. The lncRNA identified as small nucleolar RNA host gene 1 ( SNHG1) is a novel lncRNA that is increased in multiple human cancers; however, the regulatory mechanism requires further investigation. In this study, we discovered that SNHG1 was markedly up-regulated in NSCLC tissues and cells and that SNHG1 silencing decreased tumor volumes. Moreover, we explored its regulatory mechanism and found that SNHG1 directly bound to microRNA (miRNA)-145-5p, isolating miR-145-5p from its target gene MTDH. Inhibition of SNHG1 suppressed NSCLC cell viability, proliferation, migration, and invasion in vitro, but its effect was rescued by miR-145-5p inhibition. These results demonstrate that SNHG1 contributes to NSCLC progression by modulating the miR-145-5p/ MTDH axis, and it could potentially be a therapeutic target as well as a diagnostic marker.-Lu, Q., Shan, S., Li, Y., Zhu, D., Jin, W., Ren, T. Long noncoding RNA SNHG1 promotes non-small cell lung cancer progression by up-regulating MTDH via sponging miR-145-5p.

SND1 is an AEG-1/MTDH/LYRIC-binding protein that is upregulated in numerous human cancers, where it has been assigned multiple functional roles. In this study, we report its association with the TGFβ1 signaling pathway, which promotes epithelial-mesenchymal transition (EMT) in breast cancer. SND1 was upregulated in breast cancer tissues, in particular in primary invasive ductal carcinomas. Transcriptional activation of the SND1 gene was controlled by the TGFβ1/Smad pathway, specifically by activation of the Smad2/Smad3 complex. The SND1 promoter region contained several Smad-specific recognition domains (RD motifs), which were recognized and bound by the Smad complex that enhanced the transcriptional activation of SND1. We found that SND1 promoted expression of the E3 ubiquitin ligase Smurf1, leading to RhoA ubiquitination and degradation. RhoA degradation in breast cancer cells disrupted F-actin cytoskeletal organization, reduced cell adhesion, increased cell migration and invasion, and promoted metastasis. Overall, our results define a novel role for SND1 in regulating breast tumorigenesis and metastasis.

Increasing results suggest microRNAs (miRNAs) could function important roles in malignant tumor progression. miR-30a-5p is downregulated in variety of cancers and acts as a cancer suppressing gene. The functions and molecular mechanisms of miRNA-30a-5p in hepatocellular carcinoma (HCC) remain unclear. In the present study, quantitative real-time PCR (qRT-PCR) was used to detect miR-30a-5p expression in 16 pairs of HCC and their adjacent non-cancerous tissues and HCC cell lines. By overexpression of miRNA-30a-5p, CCK-8 and colon formation assay were used to evaluate cell growth and flow cytometry to evaluate cell apoptosis. Western blot was used to test protein expression. And potential mechanisms were analyzed with luciferase activity assay. In vivo HepG2 tumor growth was observed with nude mice. Our results showed that miR-30a-5p expression in HCC tissues was significantly lower compared to adjacent non-cancerous liver tissues, and lower miR-30a-5p expression was also observed in HCC cell lines compared to normal liver cell. Luciferase assay showed that metadherin (MTDH) mRNA was a direct target of miR-30a-5p. A significant reverse correlation between miR-30a-5p and MTDH in liver cancer tissues was observed. miR-30a-5p overexpression in HCC cells significantly inhibited cell proliferation, colon formation, and induced apoptosis while MTDH overexpression reversed growth inhibition and apoptosis induction of miRNA-30a-5p in HCC cells. miRNA-30a-5p upregulated phosphatase and tensin homolog (PTEN) protein expression and thus inhibited AKT activating by targeting MTDH. miRNA-30a-5p also significantly inhibited HepG2 tumor growth in vivo. Our results suggest that underexpression of miR-30a-5p might function as a tumor suppressing miRNA by directly targeting MTDH in HCC and is therefore a potential candidate biomarker for HCC targeting therapy.

Patients with lung adenocarcinoma may benefit from recently developed molecular targeted therapies. However, analogous advanced treatments are not available for patients with lung squamous cell carcinoma (lung SCC). The survival rate of patients with the advanced stage of lung SCC remains poor. Exploration of novel lung SCC oncogenic pathways might lead to new treatment protocols for the disease. Based on this concept, we have identified microRNA- (miRNA) mediated oncogenic pathways in lung SCC. It is well known that miR-145-5p (the guide strand) functions as a tumor suppressor in several types of cancer. However, the impact of miR-145-3p (the passenger strand) on cancer cells is still ambiguous. Expression levels of miR-145-5p and miR-145-3p were markedly reduced in cancer tissues, and ectopic expression of these miRNAs inhibited cancer cell aggressiveness, suggesting that both miR-145-3p as well as miR-145-5p acted as antitumor miRNAs. We identified seven putative target genes (MTDH, EPN3, TPD52, CYP27B1, LMAN1, STAT1 and TXNDC12) that were coordinately regulated by miR-145-5p and miR-145-3p in lung SCC. Among the seven genes, we found that metadherin (MTDH) was a direct target of these miRNAs. Kaplan-Meier survival curves showed that high expression of MTDH predicted reduced survival of lung SCC patients. We investigated pathways downstream from MTDH by using genome-wide gene expression analysis. Our data showed that several anti-apoptosis and pro-proliferation genes were involved in pathways downstream from MTDH in lung SCC. Taken together, both strands of miR-145, miR-145-5p and miR-145-3p are functional and play pivotal roles as antitumor miRNAs in lung SCC.

Metastasis is the principal cause of cancer death and occurs through multiple, complex processes that involve the concerted action of many genes. A number of studies have indicated that the Fragile Histidine Triad (FHIT) gene product, FHIT, functions as a tumor suppressor in a variety of common human cancers. Although there are suggestions of a role for FHIT loss in progression of various cancers, a role for such loss in metastasis has not been defined. Here, via in vivo and in vitro assays, we reveal that the enforced expression of FHIT significantly suppresses metastasis, accompanied by inhibition of the epithelial-mesenchymal transition (EMT), a process involved in metastasis through coordinate modulation of EMT-related genes. Specifically, miR-30c, a FHIT-upregulated microRNA, contributes to FHIT function in suppression of EMT and metastasis by directly targeting metastasis genes Metadherin (MTDH), High-mobility group AT-hook 2 (HMGA2), and the mesenchymal markers, Vimentin (VIM) and Fibronectin (FN1), in human lung cancer. Finally, we demonstrate that the expression pattern of FHIT and miR-30c is inversely correlated with that of MTDH and HMGA2 in normal tissue, non-metastatic and metastatic tumors, serving as a potential biomarker for metastasis in lung cancer.

Hepatocellular carcinoma (HCC) is a highly virulent malignancy with diverse etiology. Identification of a common mediator of aggressive progression of HCC would be extremely beneficial not only for diagnostic/prognostic purposes but also for developing targeted therapies. AEG-1/MTDH/LYRIC gene is amplified in human HCC patients, and overexpression of AEG-1/MTDH/LYRIC has been identified in a high percentage of both hepatitis B virus and hepatitis C virus positive HCC cases, suggesting its key role in regulating hepatocarcinogenesis. Important insights into the molecular mechanisms mediating oncogenic properties of AEG-1/MTDH/LYRIC, especially regulating chemoresistance, angiogenesis, and metastasis, have been obtained from studies using HCC model. Additionally, analysis of HCC model has facilitated the identification of AEG-1/MTDH/LYRIC downstream genes and interacting proteins, thereby unraveling novel players regulating HCC development and progression leading to the development of novel interventional strategies. Characterization of a hepatocyte-specific AEG-1/MTDH/LYRIC transgenic mouse (Alb/AEG-1) has revealed novel aspects of AEG-1/MTDH/LYRIC function in in vivo contexts. Combination of AEG-1/MTDH/LYRIC inhibition and chemotherapy has documented significant efficacy in abrogating human HCC xenografts in nude mice indicating the need for developing effective AEG-1/MTDH/LYRIC inhibition strategies to obtain objective response and survival benefits in terminal HCC patients.

Endothelial cells (ECs) are critical for angiogenesis, and microRNA plays important roles in this process. In this study, we investigated the function and mechanism of miR-302c in the process of endothelial-mesenchymal transition (EndMT) in ECs. When miR-302c was overexpressed in HUVECs, the motility of the HUVECs was weakened; the expression levels of EndMT markers were also changed: vascular endothelial (VE)-cadherin was up-regulated, whereas β-catenin, FSP1, and α-SMA were down-regulated. Further in vivo and in vitro experiments showed that the growth of HCC was inhibited when co-cultured or co-injected with HUVECs overexpressing miR-302c. On the contrary, when miR-302c was suppressed in HUVECs, the opposite results were observed. Reporter assays showed that miR-302c inhibited metadherin (MTDH) expression through directly binding to its 3'UTR. In addition, compared to ECs isolated from normal liver tissues of HCC patients, ECs isolated from tumor tissues expressed markedly low levels of miR-302c but high levels of MTDH. These results suggest that EC-specific miR-302c suppresses tumor growth in HCC through MTDH-mediated inhibition of EndMT. MTDH and miR-302c might provide a new strategy for anti-angiogenic therapy in HCC.

BACKGROUND

Ovarian cancer is the most lethal gynaecological cancer. Progression-free and overall survival is significantly related to surgical success and residual disease volume. It is unclear whether this survival advantage is due to an intrinsic biological element of the tumour cells which enables successful surgery and improved prognosis, or alternatively the number of tumour sustaining cells remaining irrespective of differences in biology.

METHODS

A systematic review of the literature was performed identifying studies that have investigated the association between biomarkers and surgical outcomes. We attempted validation of these results using The Cancer Genome Atlas ovarian cancer data sets.

RESULTS

Thirty studies were identified of which sixteen determined protein expression, eight gene expression and one DNA methylation in association with surgical debulking. Individualised linear models adjusting for batch, stage and age identified only expression of the genes MTDH and insulin-like growth factor-1 receptor (IGF1R) to be significantly associated with debulking surgery (P<0.05, false discovery rate (FDR)<5%), although in the case of IGF1R this was in the opposite direction to previous findings.

CONCLUSIONS

The majority of studies are limited by design, include heterogeneous samples and lack adjustment for major confounding factors. High quality detailed clinical annotations should be routinely collected in future to more accurately evaluate biomarkers of surgical outcome.

AEG-1/MTDH/LYRIC has been shown to promote cancer progression and development. Overexpression of AEG-1/MTDH/LYRIC correlates with angiogenesis, metastasis, and chemoresistance to various chemotherapy agents in cancer cells originating from a variety of tissues. In this chapter, we focus on the role of AEG-1/MTDH/LYRIC in drug resistance. Mechanistic studies have shown that AEG-1/MTDH/LYRIC is involved in classical oncogenic pathways including Ha-Ras, myc, NFκB, and PI3K/Akt. AEG-1/MTDH/LYRIC also promotes protective autophagy by activating AMP kinase and autophagy-related gene 5. Another reported mechanism by which AEG-1/MTDH/LYRIC regulates drug resistance is by increasing loading of multidrug resistance gene (MDR) 1 mRNA to the polysome, thereby facilitating MDR1 protein translation. More recently, a novel function for AEG-1/MTDH/LYRIC as an RNA-binding protein was elucidated, which has the potential to impact expression of drug sensitivity or resistance genes. Finally, AEG-1/MTDH/LYRIC acts in microRNA-directed gene silencing via an interaction with staphylococcal nuclease and tudor domain containing 1, a component of the RNA-induced silencing complex. Altered microRNA expression and activity induced by AEG-1/MTDH/LYRIC represent an additional way that AEG-1/MTDH/LYRIC may cause drug resistance in cancer. The multiple functions of AEG-1/MTDH/LYRIC in drug resistance highlight that it is a viable target as an anticancer agent for a wide variety of cancers.

The aim of this study was to determine whether histone acetylation regulates tumor suppressive microRNAs (miRNAs) in esophageal squamous cell carcinoma (ESCC) and to identify genes which are regulated by these miRNAs. We identified a miRNA that was highly upregulated in an ESCC cell line by cyclic hydroxamic acid-containing peptide 31 (CHAP31), one of the histone deacetylase inhibitors (HDACIs), using a miRNA array analysis. miR-375 was strongly upregulated by CHAP31 treatment in an ESCC cell line. The expression levels of the most upregulated miRNA, miR-375 were analyzed by quantitative real-time PCR in human ESCC specimens. The tumor suppressive function of miR-375 was revealed by restoration of miR-375 in ESCC cell lines. We performed a microarray analysis to identify target genes of miR-375. The mRNA and protein expression levels of these genes were verified in ESCC clinical specimens. LDHB and AEG-1/MTDH were detected as miR‑375-targeted genes. The restoration of miR-375 suppressed the expression of LDHB and AEG-1/MTDH. The ESCC clinical specimens exhibited a high level of LDHB expression at both the mRNA and protein levels. A loss-of-function assay using a siRNA analysis was performed to examine the oncogenic function of the gene. Knockdown of LDHB by RNAi showed a tumor suppressive function in the ESCC cells. The correlation between gene expression and clinicopathological features was investigated by immunohistochemistry for 94 cases of ESCC. The positive staining of LDHB correlated significantly with lymph node metastasis and tumor stage. It also had a tendency to be associated with a poor prognosis. Our results indicate that HDACIs upregulate miRNAs, at least some of which act as tumor suppressors. LDHB, which is regulated by the tumor suppressive miR-375, may therefore act as an oncogene in ESCC.

Cancer stem-like cells (CSC) are a cell subpopulation that can reinitiate tumors, resist chemotherapy, and give rise to metastases. Metadherin (MTDH) contributes widely to tumor growth, drug resistance, relapse, and metastasis, but its molecular mechanisms of action are not well understood. Here, we report that MTDH drives CSC expansion by promoting the expression of TWIST1, a transcription factor critical for cancer cell stemness and metastasis. MTDH activates TWIST1 expression indirectly by facilitating histone H3 acetylation on the TWIST1 promoter, a process mediated by the histone acetyltransferase CBP. Mechanistic investigations showed that MTDH interacts with CBP and prevents its ubiquitin-mediated degradation, licensing its transcriptional activation of TWIST1. In clinical specimens of breast cancer, MTDH expression correlates positively with TWIST1 expression and CSC abundance. Overall, our work revealed that MTDH promotes CSC accumulation and breast tumorigenicity by regulating TWIST1, deepening the understanding of MTDH function in cancer.

Activation of the oncogene AEG-1 (MTDH, LYRIC) has been implicated recently in the development of hepatocellular carcinoma (HCC). In mice, HCC can be initiated by exposure to the carcinogen DEN, which has been shown to rely upon activation of NF-κB in liver macrophages. Because AEG-1 is an essential component of NF-κB activation, we interrogated the susceptibility of mice lacking the AEG-1 gene to DEN-induced hepatocarcinogenesis. AEG-1-deficient mice displayed resistance to DEN-induced HCC and lung metastasis. No difference was observed in the response to growth factor signaling or activation of AKT, ERK, and β-catenin, compared with wild-type control animals. However, AEG-1-deficient hepatocytes and macrophages exhibited a relative defect in NF-κB activation. Mechanistic investigations showed that IL6 production and STAT3 activation, two key mediators of HCC development, were also deficient along with other biologic and epigenetics findings in the tumor microenvironment, confirming that AEG-1 supports an NF-κB-mediated inflammatory state that drives HCC development. Overall, our findings offer in vivo proofs that AEG-1 is essential for NF-κB activation and hepatocarcinogenesis, and they reveal new roles for AEG-1 in shaping the tumor microenvironment for HCC development.