Vimentin Promoter Research Articles

Vimentin-Mediated Steroidogenesis Induced by Phthalate Esters: Involvement of DNA Demethylation and Nuclear Factor κB.

Di-n-butyl phthalate (DBP) and its active metabolite, monobutyl phthalate (MBP) are the most common endocrine disrupting chemicals. Many studies indicate that high-doses of DBP and/or MBP exhibit toxicity on testicular function, however, little attention have been paid to the effects of low levels of DBP/MBP on steroidogenesis. As we all know, the steroidogenic acute regulatory protein (StAR) is a key regulator involved in the steroidogenesis. Here we found that, in addition to StAR, MBP/DBP increased the steroidogenesis by a cytoskeletal protein, vimentin. Briefly, in murine adrenocortical tumor (Y1) and the mouse Leydig tumor (MLTC-1) cells, vimentin regulated the secretion of progesterone. When these two cells were exposure to MBP, the DNA demethylation in the vimentin promoter was observed. In addition, MBP also induced the activation of nuclear factor kappa B (NF-κB, a transcriptional regulator of vimentin). These two processes improved the transcriptional elevation of vimentin. Knockdown of NF-κB/vimentin signaling blocked the DBP/MBP-induced steroidogenesis. These in vitro results were also confirmed via an in vivo model. By identifying a mechanism whereby DBP/MBP regulates vimentin, our results expand the understanding of the endocrine disrupting potential of phthalate esters.

SET8 induces epithelial‑mesenchymal transition and enhances prostate cancer cell metastasis by cooperating with ZEB1.

Mounting evidence suggested that histone H4K20-specific methyltransferase SET8 is required to maintain the malignant phenotype of various cancer types; however, the role of SET8 in mediating tumor metastasis in prostate cancer (PCa) has remained elusive. The present study demonstrated that small interfering RNA-mediated knockdown of SET8 inhibited the invasive potential of the PCa cell line PC-3 in vitro. Knockdown of SET8 reduced sphere formation, downregulated E-cadherin and α-catenin, and upregulated N-cadherin and vimentin expression in CaP cells, while upregulation of SET8 expression with a recombinant plasmid had the opposite effect. Furthermore, SET8 was shown to be physically associated with the epithelial-mesenchymal transition (EMT) inducer zinc finger E-box-binding homeobox 1 (ZEB1) in PCa cell lines. Chromatin immunoprecipitation suggested that SET8 binds to the promoter of cell adhesion molecule E-cadherin and vimentin. Luciferase reporter assays suggested that E-cadherin and vimentin are direct targets of SET8; furthermore, loss- and gain-of function studies of SET8 and ZEB1 indicated that suppression of downstream E-cadherin and activation of vimentin are important mechanisms by which SET8 and ZEB1 cooperatively trigger metastasis. Furthermore, SET8-induced methylated H4K20 was indicated to exert a dual function in ZEB1-regulated gene expression. In conclusion, the present study revealed that SET8 and ZEB1 are functionally interdependent in promoting the EMT and enhancing the invasive potential of PCa cells in vitro.

DNA hypermethylation of the vimentin gene inversely correlates with vimentin expression in intestinal- and diffuse-type gastric cancer.

The vimentin gene is a hallmark of epithelial-to-mesenchymal transition and has been observed to be overexpressed in various types of tumor cell line and tissue. Previous studies have reported correlations between vimentin DNA methylation levels and subsequent vimentin expression levels in solid tumors, including breast and colorectal cancer; however, to the best of our knowledge, such a correlation has not been reported for gastric cancer (GC) using Lauren classification. Therefore, the present study aimed to quantify DNA methylation levels of the vimentin gene using quantitative (q) methylation-specific polymerase chain reaction (PCR) in intestinal-type GC cell lines (MKN-28, AGS and MKN-1), diffuse-type GC cell lines (SGC-7901, SNU-5 and KATO III), the GES-1 immortalized human non-neoplastic gastric epithelial cell line, as well as in tumor and paratumor normal tissue samples. Furthermore, the present study analyzed the messenger RNA expression of the vimentin gene in these cell lines and tissues by reverse transcription-qPCR. A comparison of the clinicopathological features was conducted between patients, grouped according to the Lauren classification. The present study identified that the vimentin promoter region was hypermethylated in all GC cell lines and tumor tissue samples when compared with immortalized normal gastric epithelial cells and paratumor normal tissues. In addition, vimentin promoter methylation levels were observed to be higher in intestinal-type cell lines when compared with those of diffuse-type lines and tissues. Correspondingly, vimentin expression levels were lower in intestinal-type gastric cell lines compared with those of diffuse-type cell lines and tissues, and were lowest in the non-neoplastic gastric cell line and paratumor normal tissues. Patients with diffuse-type GC were on average younger (P=0.023), and exhibited higher tumor (P=0.020), node (P=0.032) and TNM classification of malignant tumor stage (P=0.039) than those with intestinal-type GC. Following treatment of AGS cells (which demonstrated the highest methylation level of the vimentin gene) with 5-aza-2'-deoxycytidine, vimentin expression was restored significantly. Thus, the present study revealed that vimentin promoter methylation levels are inversely correlated with vimentin expression levels in GC (according to Lauren classification). High levels of methylation in the vimentin gene promoter region may be involved in carcinogenesis and the development of GC, and may provide a novel molecular classification for GC.

Decrease of phosphorylated proto-oncogene CREB at Ser 133 site inhibits growth and metastatic activity of renal cell cancer

Objective: Cyclic-AMP-responsive element-binding protein (CREB) is a proto-oncogenic transcription factor. The authors’ previous reports showed that blocking the CREB binding site at Ser 133 inhibited the expression of target genes, which related to the progression of some tumors. In this study, the authors investigated the role of phosphorylated CREB (pCREB) at Ser133 in renal cell carcinoma (RCC) growth and metastases.Methods: Immunohistochemistry, xenograft model in nude mice, cell proliferation assay, cell invasion/migration assay, fluorescent immunocytochemistry and Western analysis were performed in an immortalized proximal tubule epithelial cell line and clear-cell RCC.Results: The authors’ results showed that knockdown of pCREB inhibited kidney cancer cells growth in vivo. Furthermore, suppression of the pCREB level blunted the capabilities of cell migration and invasion in vitro and was accompanied with significantly decreased expression of MMP-2 and MMP-9, the filopodia formation and epithelial-mesenchymal transition-related proteins. Surprisingly, no changes of expression or location of vimentin were revealed in the experiment. Bioinformatic software explained the possible reason for this is that the promoter of vimentin does not contain the CRE sequence.Conclusions: These data suggest that decreasing the level of pCREB inhibits the growth and metastasis of RCC by targeting the Ser 133 site.

Pharmacological and Morphological Evidence of AMPK-Mediated Energy Sensing in the Lower Brain Stem Ependymocytes to Control Reproduction in Female Rodents.

Ependymocytes are one of the energy-sensing cells that regulate animal reproduction through their responsiveness to changes in extracellular glucose levels and the expression of pancreatic-type glucokinase and glucose transporter 2, which play a critical role in sensing blood glucose levels in pancreatic β-cells. Molecular mechanisms underlying glucose sensing in the ependymocytes remain poorly understood. The AMP-activated protein kinase (AMPK), a serine/threonine kinase highly conserved in all eukaryotic cells, has been suggested to be an intracellular fuel gauge that detects cellular energy status. The present study aims to clarify the role AMPK of the lower brainstem ependymocytes has in sensing glucose levels to regulate reproductive functions. First, we will show that administration of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, an AMPK activator, into the 4th ventricle suppressed pulsatile LH release in female rats. Second, we will demonstrate the presence of AMPK catalytic subunit immunoreactivities in the rat lower brainstem ependymocytes. Third, transgenic mice were generated to visualize the ependymocytes with Venus, a green fluorescent protein, expressed under the control of the mouse vimentin promoter for further in vitro study. The Venus-labeled ependymocytes taken from the lower brainstem of transgenic mice revealed that AMPK activation by 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, an AMPK activator, increased in vitro intracellular calcium concentrations. Taken together, malnutrition-induced AMPK activation of ependymocytes of the lower brainstem might be involved in suppression of GnRH/LH release and then gonadal activities.

Head-to-head antisense transcription and R-loop formation promotes transcriptional activation

The mechanisms used by antisense transcripts to regulate their corresponding sense mRNAs are not fully understood. Herein, we have addressed this issue for the vimentin (VIM) gene, a member of the intermediate filament family involved in cell and tissue integrity that is deregulated in different types of cancer. VIM mRNA levels are positively correlated with the expression of a previously uncharacterized head-to-head antisense transcript, both transcripts being silenced in colon primary tumors concomitant with promoter hypermethylation. Furthermore, antisense transcription promotes formation of an R-loop structure that can be disfavored in vitro and in vivo by ribonuclease H1 overexpression, resulting in VIM down-regulation. Antisense knockdown and R-loop destabilization both result in chromatin compaction around the VIM promoter and a reduction in the binding of transcriptional activators of the NF-κB pathway. These results are the first examples to our knowledge of R-loop-mediated enhancement of gene expression involving head-to-head antisense transcription at a cancer-related locus.

β-arrestin-1 mediates nicotine-induced metastasis through E2F1 target genes that modulate epithelial-mesenchymal transition.

Cigarette smoking is a major risk factor in the development of non-small cell lung cancer (NSCLC), which accounts for 80% of all lung cancers. Nicotine, the major addictive component of tobacco smoke, can induce proliferation, invasion, and epithelial-to-mesenchymal transition (EMT) in NSCLC cell lines and promote metastasis of NSCLC in mice. Here, we demonstrate that the scaffolding protein β-arrestin-1 is necessary for nicotine-mediated induction of mesenchymal genes vimentin and fibronectin as well as EMT regulators ZEB1 and ZEB2. Nicotine induced changes in cell morphology and ablate tight junctions consistent with EMT; β-arrestin-1, but not β-arrestin-2, was required for these changes. β-Arrestin-1 promoted the expression of the mesenchymal genes, as well as ZEB1 and ZEB2, through the mediation of the E2F1 transcription factor; this required Src kinase activity. Stimulation of multiple NSCLC cell lines with nicotine led to enhanced recruitment of β-arrestin-1 and E2F1 on vimentin, fibronectin, and ZEB1 and ZEB2 promoters. Furthermore, there was significantly more β-arrestin-1 and E2F1 associated with these promoters in human NSCLC tumors, and β-arrestin-1 levels correlated with vimentin and fibronectin levels in human NSCLC samples. A549-luciferase cells lacking β-arrestin-1 showed a significantly reduced capacity for tumor growth and metastasis when orthotopically implanted into the lungs of SCID-beige mice. Taken together, these studies reveal a novel role for β-arrestin-1 in the growth and metastasis of NSCLC.

Abstract 4282: High content multiparametric functional screen for regulators of epithelial-mesenchymal transition identifies genes associated with chemoresistance

Abstract Metastasis accounts for the majority of treatment-refractory cancers and poor prognosis of the disease. The phenotypic transition of non-motile epithelial tumor cells to migratory and invasive ‘mesenchymal’ cells enables the escape of cancer cells from the primary tumor into the circulation. Morphological changes from cobblestone epithelial cells to elongated and spindle-shaped cells is a key feature of this process. This transition is also marked by upregulation of vimentin, an intermediate filament found in mesenchymal cells. We have previously developed a bladder cancer model with a step-wise enhancement in the metastatic cascade that we have used to interrogate the role of tumor cell plasticity in metastasis (1). Given the need to elucidate pathways and assign functions to particular genes involved in this process, we conducted a high content screening assay across genome wide siRNA, miRNA and kinase inhibitor (131 compounds) libraries to systematically identify modulators of EMT/MET. We identified candidate gene regulators of EMT in TSU-Pr1-B1 bladder cancer cells using the readouts of morphological change (cells stained with CMFDA) and a vimentin promoter activity (dsRed reporter construct). Following integration of the predicted target genes for miRNA hits and kinase inhibitors with siRNA hits, initial validation using a siRNA deconvolution strategy was performed for 400 targets. 221 siRNAs were classified as inducing statistically significant effects on cell shape and/or vimentin promoter reporter activity (defined as at least 2/4 duplexes inducing the effect for a given target). Gene ontology and pathway analyses feature cell cycle and various developmental pathways. Furthermore, the validated gene list was associated with bladder cancer histology and drug sensitivity in clinical specimens in multiple cancer types (Oncomine). Molecules identified in this assay will be further analysed using functional assays to determine their role in maintaining the epithelial phenotype and as regulators of chemoresistance. (1) Chaffer et al. (2005) Clin Exp Metastasis 22: 115-25. Citation Format: Elizabeth D. Williams, Nur Akmarina Said, Cathryn M. Gould, Erik W. Thompson, Kaylene J. Simpson. High content multiparametric functional screen for regulators of epithelial-mesenchymal transition identifies genes associated with chemoresistance. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4282. doi:10.1158/1538-7445.AM2014-4282

Abstract 2301: Cross validation of NGS methylated targets using droplet digital PCR (ddPCR)

Abstract DNA methylation is one of the most studied epigenetic modifications. DNA methylation plays an important role in a number of physiological processes as well as common diseases such as cancer and neurodegenerative disorders. In mammals, DNA methylation occurs at the C-5 position of cytosine in CpG dinucle¬otide sequences, which are mainly concentrated in regions known as CpG islands. Methylation in CpG islands within gene promoters usually leads to gene silencing. Recent data have shown the correlation of methylation and disease status. However, there are significant limitations in both biology and technology. Biologically, methylation status is highly heterogeneous in nature. In normal controls there is never a complete lack of methylation marks, and conversely, never a completely saturated methylation signature. In addition methylation sites of interest are often located in CpG islands, regions where multiple methylation sites occur side by side, making assay design and discrimination challenging. Technological hurdles add significant variability as well. The typical method for determining methylation is bisulfite conversion, which uses harsh chemicals to convert cytosines to uracil. When a cytosine is methylated, it is largely, though not completely, protected from the conversion process. However, bisulfite conversion also causes a great deal of DNA damage, causing the strands to separate and fragment. In most cases of research, the DNAs that researchers want to examine are from FFPE or cfDNA samples, samples which are already both limited and damaged. Because of these challenges, there is an unmet need for a sensitive yet robust method to analyze DNA methylation in clinical samples in a rapid, inexpensive, and high throughput manner. Herein we showcase the use of ddPCR for detection of DNA methylation in bisulfite converted gDNA samples. First we demonstrate the superior sensitivity, linearity and robustness of ddPCR methylation detection in the SNRPN promoter, a model system for an imprinted gene involved in neurological disorders. Secondly we show the detection of DNA methylation in the vimentin promoter, which is known to be methylated in cancer (Li et al. Nat. Biotech. 2009). We will demonstrate reproducible detection in replicate bisulfite converted samples and sensitivity. Citation Format: Dawne N. Shelton, Claudia Litterst, John F. Regan, Helen R. Moinova, Sanford D. Markowitz. Cross validation of NGS methylated targets using droplet digital PCR (ddPCR). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2301. doi:10.1158/1538-7445.AM2014-2301

562P - Detection of Colorectal Neoplasm Using Promoter Methylation of Stool Dna in Stool Samples in Korean Patients

ABSTRACT Aim: Colorectal cancer screening using stool DNA has yielded greater detection rate than conventional fecal ocult blood testing. The aim of this study was to determine the sensitivity and specificity of detection method for colorectal adenomas and colorectal carcinoma(CRC) using SFRP2, TFPI2, NDRG4, BMP3 and Vimentin promoter methylation. Methods: The methylation status of SFRP2, TFPI2, NDRG4, BMP3 and Vimentin promoters in bisulfate modified stool DNA was investigated in blinded manner with methylation specific PCR from 40 endoscopically diagnosed healthy controls, 36 patients with colorectal adenoma and 35 patients with CRC. Results: Methylated SFRP2, TFPI2, NDRG4, BMP3 and Vimentin promoters were detected in 60.0%, 31.4%, 68.8%, 40.0% and 5.7% of CRC samples and 27.8%, 27.8%, 27.8%, 33.3% and 5.6% of the colorectal adenoma. Their specificity of study using five markers is 80.3%, 81.6%, 76.3%, 76.3% and 97.4% of the CRC samples and 65.3%, 80.0%, 57.3%, 73.3% and 97.3% of colorectal adenoma, resectively. Conclusions: Our results demonstrated that SFRP2, TFPI2, NDRG4, BMP3 and Vimentin promoter methylation in stool samples had high sensitivity and specificity for the detection of CRC. This new developed screening may be useful non-invasive alternative screening for CRC detection. Disclosure: All authors have declared no conflicts of interest.

DNA methylation analysis of SFRP2, GATA4/5, NDRG4 and VIM for the detection of colorectal cancer in fecal DNA.

Aberrantly methylated genes are increasingly being established as biomarkers for the detection of colorectal cancer (CRC). In the present study, the methylation levels of the secreted frizzled-related protein gene 2 (SFRP2), GATA binding protein 4/5 (GATA4/5), N-Myc downstream-regulated gene 4 (NDRG4) and vimentin (VIM) promoters were evaluated for their use as markers in the noninvasive detection of CRC. Methylation-specific polymerase chain reaction was performed to analyze promoter CpG methylation of SFRP2, GATA4/5, NDRG4 and VIM in the fecal DNA of 56 patients with CRC and 40 individuals exhibiting normal colonoscopy results. Promoter methylation levels of SFRP2, GATA4/5, NDRG4 and VIM in CRC patients were 57.1% (32/56), 42.9% (24/56), 83.9% (47/56), 28.6% (16/56) and 41.1% (23/56), respectively. Furthermore, the specificity of the genes were 90.0% (4/40), 95.0% (2/40), 82.5% (7/40), 97.5% (4/40) and 85.0% (6/40), respectively. The overall sensitivity of detection for fecal DNA with at least one methylated gene was 96.4% (54/56) in CRC patients. By contrast, only 14 of the 40 normal individuals exhibited methylated DNA in the aforementioned promoter regions. Methylation of the SFRP2, GATA4/5, NDRG4 and VIM promoters in fecal DNA is associated with the presence of colorectal tumors. Therefore, the detection of aberrantly methylated DNA in fecal samples may present a promising, noninvasive screening method for CRC.

Aberrant promoter methylation of the vimentin gene may contribute to colorectal carcinogenesis: a meta-analysis

This meta-analysis of published cohort studies was conducted to evaluate how closely the promoter methylation of the vimentin gene is correlated with the pathogenesis of colorectal carcinogenesis (CRC). The Web of Science (1945 ~ 2013), Cochrane Library Database (issue 12, 2013), PubMed (1966 ~ 2013), EMBASE (1980 ~ 2013), CINAHL (1982 ~ 2013), and Chinese Biomedical Database (CBM) (1982 ~ 2013) were searched without language restrictions. Meta-analyses were conducted using Stata software (Version 12.0, Stata Corporation, College Station, TX, USA). Odds ratios (ORs) and 95 % confidence intervals (95 %CI) were calculated. Seven clinical cohort studies with a total of 467 CRC subjects met our inclusion criteria. Our meta-analysis results demonstrated that the frequency of vimentin promoter methylation in cancer tissues was significantly higher than in normal and benign tissues (cancer tissues vs. normal tissues: OR = 32.41, 95 %CI = 21.04 ~ 49.93, P < 0.001; cancer tissues vs. benign tissues: OR = 1.60, 95 %CI 1.05 ~ 2.42, P = 0.028). Ethnicity-stratified analysis indicated that the frequency of aberrant vimentin promoter methylation was correlated with the pathogenesis of CRC in both Asians and Caucasians. The findings of our meta-analysis confirm that vimentin methylation may play a crucial role in the pathogenesis of CRC.

JMJD2B Promotes Epithelial–Mesenchymal Transition by Cooperating with β-Catenin and Enhances Gastric Cancer Metastasis

This study investigated the role of histone demethylase Jumonji domain-containing protein 2B (JMJD2B) in promoting epithelial-mesenchymal transition (EMT) and underlying molecular mechanisms in the progression of gastric cancer. The induction of EMT by JMJD2B in gastric cancer cells and its underlying mechanisms were examined by a series of assays. In vivo and in vitro assays were performed to clarify invasive potential of JMJD2B in gastric cancer cells. The expression dynamics of JMJD2B were detected using immunohistochemistry in 101 cases of primary gastric cancer tissues. Inhibition of JMJD2B by specific siRNA suppresses EMT of gastric cancer cells, whereas ectopic expression of JMJD2B induces EMT. Importantly, JMJD2B is physically associated with β-catenin and enhances its nuclear localization and transcriptional activity. JMJD2B, together with β-catenin, binds to the promoter of the β-catenin target gene vimentin to increase its transcription by inducing H3K9 demethylation locally. JMJD2B inhibition attenuates migration and invasion of gastric cancer cells in vitro and metastasis in vivo. The expression of JMJD2B was positively correlated with tumor size (P = 0.017), differentiation status (P = 0.002), tumor invasion (P = 0.045), lymph node metastasis (P = 0.000), distant metastasis (P = 0.024), and tumor-node-metastasis (TNM) stage (P = 0.002) in patients with gastric cancer. The data reveal a novel function of JMJD2B in promoting EMT and gastric cancer invasion and metastasis, implicating JMJD2B as a potential target for reversing EMT and intervention of the progression of gastric cancer.

Abstract 43: Detection of bladder cancer-associated gene methylation using next-gen bisulfite sequencing.

Abstract DNA methylation profiling of bladder cancer specific gene promoters has been shown to be a sensitive and specific diagnostic tool for early- and late-stage bladder cancer. We have recently shown that a urine-based assay that combines DNA and protein biomarkers can accurately triage patients undergoing evaluation for bladder cancer. As part of this assay, hypermethylation of Twist1 and Nid2 is performed by conventional methylation-specific PCR (cMSP). To increase throughput and lower cost, we have now developed an approach to determine the methylation at single-base resolution of CpG sites using next generation bisulfite sequencing. In addition to Twist1 and Nid2, methylation of the Vimentin promoter, which has been shown to be associated with epithelial to mesenchymal transition (EMT) in bladder cancer, was also evaluated using this technique. To determine the sensitivity of this approach, amplification was performed on control bisulfite converted genomic DNA that was either enzymatically methylated or chemically unmethylated at CpG sites using non-methylation specific PCR. Twist1, Nid2 and Vimentin PCR products were subsequently used as template for emulsion PCR and sequenced using the Ion Torrent PGM. Methylation status was determined by aligning sequencing reads to unmethylated reference sequences. In this assay, 0.4% methylated DNA could be reliably detected in 10 ng of bisulfite converted DNA, more than doubling the sensitivity of the current assay as well as potentially generating a single-base resolution mapping of additional CpG sites not yet quantified for Twist1, Nid2 and Vimentin. The clinical performance of the Next-Gen bisulfite sequencing assays for Twist1, Nid2 and Vimentin is currently being tested using urine samples from patients with bladder cancer as well as from age matched individuals who present with hematuria but who are found to be cancer-free. The technique we have developed could be used to detect other hypermethylated genes in a variety of bodily fluids where percent methylation may be much lower than in tumor tissue samples. Citation Format: Andrew R. Dunn, Shuqiang Li, Cecilia A. Fernandez, Anthony P. Shuber. Detection of bladder cancer-associated gene methylation using next-gen bisulfite sequencing. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 43. doi:10.1158/1538-7445.AM2013-43

Identification and Cytoprotective Function of a Novel Nestin Isoform, Nes-S, in Dorsal Root Ganglia Neurons

In this study, the first nestin isoform, Nes-S, was identified in neurons of dorsal root ganglia (DRG) of adult rats. Nes-S cannot form filaments by itself in cytoplasmic intermediate filament-free SW13 cells. Instead, it co-assembles into filaments with vimentin when transfected into vimentin(+) SW13 cells, and with peripherin and neurofilament proteins when transfected into N2a cells. In primary DRG neurons, endogenous Nes-S co-assembles with peripherin and neurofilament proteins. The expression of Nes-S first appears in DRG at postnatal day 5 and persists to adulthood. Among the adult tissues we examined, the expression of Nes-S is restricted to the sensory and motor neurons. Finally, exogenous Nes-S enhances viability when transfected into N2a cells, and knockdown of endogenous Nes-S impairs the survival of DRG neurons in primary cultures. Taken together, Nes-S is a new neuronal intermediate filament protein that exerts a cytoprotective function in mature sensory and motor neurons.

Abstract C84: Application of sensitive EMT reporter to identification of breast cancer stem cell-related genes

Abstract Epithelial-mesenchymal transition (EMT) is a key feature in breast cancer stem cell. In order to identify genes responsible for EMT/stemness, we have established a novel reporter system, in which mammary epithelial cells undergoing EMT can be visualized and positively selected by expression of GFP and blasticidine-resistant (BsR) genes, respectively. By incorporating tetracycline-responsive transactivator (rTA) and tetracycline-responsive element (TRE), vimentin promoter activity could be successfully amplified, which make it possible to induce sufficient Bsr/GFP fusion protein. Snail introduction can induce GFP+ CD44hi population by 30%. Using this reporter cell line, cDNA libraries derived from aggressive breast cancer cell lines MDA-MB-231 and BT549 were screened. Snail cDNA was isolated from several clones with GFP+ CD44hi. An shRNA library screening identified several candidate genes, which might be responsible for maintenance of epithelial phenotype. GFP-positive epithelial cells were identified in the original cells, which enable us to identify early EMT markers. By replacing the vimentin promoter with E-cadherin promoter, we could successfully establish a reporter system for mesenchymal-epithelial transition (MET). Through these attempts, we are aiming to identify molecular targets in breast cancer stem cell and triple-negative breast cancer. Citation Format: Kiyotsugu Yoshikawa, Yoshiaki Matsumoto, Junji Ito, Yoshie Shiojiri, Ellis Reinherz, Masakazu Toi. Application of sensitive EMT reporter to identification of breast cancer stem cell-related genes. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C84.

Vimentin DNA methylation predicts survival in breast cancer

The Vimentin gene plays a pivotal role in epithelial-to-mesenchymal transition and is known to be overexpressed in the prognostically poor basal-like breast cancer subtype. Recent studies have reported Vimentin DNA methylation in association with poor clinical outcomes in other solid tumors, but not in breast cancer. We therefore quantified Vimentin DNA methylation using MALDI-TOF mass spectrometry in breast tumors and matched normal pairs in association with gene expression and survival in a hospital-based study of breast cancer patients. Gene expression data via qRT-PCR in cell lines and oligomicroarray data from breast tissues were correlated with percent methylation in the Vimentin promoter. A threshold of 20 percent average methylation compared with matched normal pairs was set for bivariate and multivariate tests of association between methylation and tumor subtype, tumor histopathology, and survival. Vimentin was differentially methylated in luminal breast cancer cell lines, and in luminal A, luminal B, and HER2-enriched breast tumor subtypes, but was rare in basal-like cell lines and tumors. Increased methylation was strongly correlated with decreased mRNA expression in cell lines, and had a moderate inverse correlation in breast tumors. Vimentin methylation predicted poor overall survival independent of race, subtype, stage, nodal status, or metastatic disease and holds promise as a new prognostic biomarker for breast cancer patients.

Telomerase reverse transcriptase promotes epithelial–mesenchymal transition and stem cell-like traits in cancer cells

Telomerase activation through induction of telomerase reverse transcriptase (hTERT) contributes to malignant transformation by stabilizing telomeres. Clinical studies demonstrate that higher hTERT expression is associated with cancer progression and poor outcomes, but the underlying mechanism is unclear. Because epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) are key factors in cancer metastasis and relapse, and hTERT has been shown to exhibit multiple biological activities independently of its telomere-lengthening function, we address a potential role of hTERT in EMT and CSCs using gastric cancer (GC) as a model. hTERT overexpression promotes, whereas its inhibition suppresses, EMT and stemness of GC cells, respectively. Transforming growth factor (TGF)-β1 and β-catenin-mediated EMT was abolished by small interfering RNA depletion of hTERT expression. hTERT interacts with β-catenin, enhances its nuclear localization and transcriptional activity, and occupies the β-catenin target vimentin promoter. All these hTERT effects were independent of its telomere-lengthening function or telomerase activity. hTERT and EMT marker expression correlates positively in GC samples. Mouse experiments demonstrate the in vivo stimulation of hTERT on cancer cell colonization. Collectively, hTERT stimulates EMT and induces stemness of cancer cells, thereby promoting cancer metastasis and recurrence. Thus, targeting hTERT may prevent cancer progression by inhibiting EMT and CSCs.

Deactivation of Hepatic Stellate Cells During Liver Fibrosis Resolution in Mice

Activated hepatic stellate cells (HSCs), the main fibrogenic cell type in the liver, undergo apoptosis after cessation of liver injury, which contributes to resolution of fibrosis. In this study, we investigated whether HSC deactivation constitutes an additional mechanism of liver fibrosis resolution. HSC activation and deactivation were investigated by single-cell PCR and genetic tracking in transgenic mice that expressed a tamoxifen-inducible CreER under control of the endogenous vimentin promoter (Vimentin-CreER). Single-cell quantitative polymerase chain reaction demonstrated activation of almost the entire HSC population in fibrotic livers, and a gradual decrease of HSC activation during fibrosis resolution, indicating deactivation of HSCs. Vimentin-CreER marked activated HSCs, demonstrated by a 6- to 16-fold induction of a membrane-bound green fluorescent protein (mGFP) Cre-reporter after injection of carbon tetrachloride, in liver and isolated HSCs, and a shift in localization of mGFP-marked HSCs from peri-sinusoidal to fibrotic septa. Tracking of mGFP-positive HSCs revealed the persistence of 40%-45% of mGFP expression in livers and isolated HSCs 30-45 days after carbon tetrachloride was no longer administered, despite normalization of fibrogenesis parameters; these findings confirm reversal of HSC activation. After fibrosis resolution, mGFP expression was observed again in desmin-positive peri-sinusoidal HSCs; no mGFP expression was detected in hepatocytes or cholangiocytes, excluding mesenchymal-epithelial transition. Notably, reverted HSCs remained in a primed state, with higher levels of responsiveness to fibrogenic stimuli. In mice, reversal of HSC activation contributes to termination of fibrogenesis during fibrosis resolution, but results in higher responsiveness of reverted HSCs to recurring fibrogenic stimulation.

ZEB2 upregulates integrin α5 expression through cooperation with Sp1 to induce invasion during epithelial–mesenchymal transition of human cancer cells

Epithelial-mesenchymal transition (EMT) is a process implicated in tumor invasion, metastasis, embryonic development and wound healing. ZEB2 is a transcription factor involved in EMT that represses E-cadherin transcription. Although E-cadherin downregulation is a major event during EMT and tumor progression, E-cadherin reduction is probably not sufficient for full invasiveness. The mechanisms by which E-cadherin transcriptional repressors induce mesenchymal genes during EMT remain largely unknown. Here, we investigated the role of ZEB2 in the induction of integrin α5 during cancer EMT and its underlying mechanism. In human cancer cells, ZEB2 was found to directly upregulate integrin α5 transcription in a manner that is independent of the regulation of E-cadherin expression. Conversely, depletion of ZEB2 by small interfering RNA suppressed integrin α5 expression, leading to reduced invasion. Suppression of integrin α5 inhibited cancer cell invasion, suggesting an important role for integrin α5 in cancer progression. Furthermore, ZEB2 was found to activate the integrin α5 and vimentin promoters by interacting with and activating the transcription factor Sp1, suggesting that cooperation between ZEB2 and Sp1 represents a novel mechanism of mesenchymal gene activation during EMT. These findings increase our understanding of the pathways beyond E-cadherin reduction that regulate mesenchymal gene expression during EMT and cancer progression.