Stimulation of RNA polymerase II elongation by hepatitis delta antigen.

Transcription elongation by RNA polymerase II (RNAPII) is negatively regulated by the human factors DRB-sensitivity inducing factor (DSIF) and negative elongation factor (NELF). A 66-kilodalton subunit of NELF (NELF-A) shows limited sequence similarity to hepatitis delta antigen (HDAg), the viral protein required for replication of hepatitis delta virus (HDV). The host RNAPII has been implicated in HDV replication, but the detailed mechanism and the role of HDAg in this process are not understood. We show that HDAg binds RNAPII directly and stimulates transcription by displacing NELF and promoting RNAPII elongation. These results suggest that HDAg may regulate RNAPII elongation during both cellular messenger RNA synthesis and HDV RNA replication.

Visceral obesity is associated with the metabolic syndrome and elevated plasma retinol binding protein-4 level in obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome (OSAS) is related to the increased prevalence of cardiovascular disease and metabolic syndrome (MS). A novel adipokine, retinol binding protein-4 (RBP4), was reported to be associated with insulin resistance and the prevalence of type 2 diabetes. To examine whether plasma RBP4 is associated with insulin resistance and MS development in OSAS, we measured plasma RBP4 levels in 181 Japanese men (24 healthy controls and 40 mild, 64 moderate, and 53 severe OSAS) of whom 26 had mild glucose intolerance with HbA1c < or = 6.0%. After a full polysomnography, blood was collected between 06:00 and 07:00 AM. Plasma RBP4 levels in moderate/severe OSAS patients were higher than in control subjects. Plasma RBP4 was not correlated with apnea variables, HOMA-IR, or blood pressure. However, it was positively correlated with visceral fat areas and plasma triglyceride levels. The prevalence of MS was higher in severe OSAS patients than in mild/moderate OSAS and control subjects. Plasma RBP4 was higher in OSAS patients with MS than in those without MS. This study indicates that plasma RBP4 is associated with dyslipidemia, but not with insulin resistance, glucose intolerance, or hypertension in patients with OSAS. Visceral obesity may play key roles in increasing the plasma RBP4 level and MS development in OSAS.

Requirement for distal upstream sequences for maximal transcription in vitro of early region IV of adenovirus.

A series of deletion mutants spanning the adenovirus early region IV (EIV) promoter were tested for transcription activity in vitro. At least three elements were found to be important for maximal transcription in HeLa whole-cell extracts. Deletion of the TATA box drastically reduced the transcription activity from the EIV promoter. Sequences between nucleotides -58 and -44 are also important for efficient transcription since deletion of this region reduced activity by 50%. More importantly, sequences residing upstream from -140 critically influence the level of EIV transcription. Deletion of sequences between nucleotides -325 (the right terminus of adenovirus genome) and -140 reduced the level of transcription more than 10-fold. It is possible that a specific cellular factor stimulates EIV transcription by recognition of these upstream sequences. The dependence of transcription from the EIV promoter on a distal upstream element may explain some aspects of the regulation of this promoter.

A specific domain of the adenovirus EIV promoter is necessary to maintain susceptibility of the integrated promoter to EIA transactivation.

We constructed a series of mutations that delete sequences in the promoter region of the early-region IV (EIV) promoter of adenovirus type 5. We fused these promoter mutations to the coding sequences of either the chloramphenicol acetyltransferase or the dihydrofolate reductase (DHFR) gene and tested the ability of a cotransfected EIa gene to stimulate EIV expression. All of the mutations tested were stimulated in these assays, implying that no specific sequence is required for stimulation. Two mutant promoters, deleted for either the TATA box or the region residing between -39 and -177 upstream from the cap site of EIV mRNA, did show a reduced level of stimulation by the EIa products. To assess the effects of the EIA gene products on expression from an EIV promoter integrated into the chromosome, we isolated CHO cell lines containing EIV-DHFR chimeric genes. After introduction of the EIa gene with a second selectable marker, expression from all mutant EIV-DHFR genes was increased. Surprisingly, one mutant promoter, deleted for sequences between -39 and -177, lost the ability to respond to the EIa region on passage of cells, although deletions in any part of the region still retained this ability. These results demonstrate that multiple elements residing between -39 and -177 in the EIV promoter are necessary to maintain susceptibility of the integrated promoter to regulation.

Regulation of in vitro and in vivo transcription of early-region IV of adenovirus type 5 by multiple cis-acting elements.

A series of deletion mutants spanning the promoter of the adenovirus early-region IV (EIV) gene were tested for transcriptional activity, using both in vitro and in vivo assays. Four distinct domains had additive effects on efficient transcription from the EIV promoter in HeLa whole-cell extracts. The first resided 20 to 27 bases upstream of the initiation site and included the TATA box. Deletion of the TATA box drastically reduced the transcriptional activity in vitro but had a lesser effect in vivo. The second region extended from -32 to -177 and contained two 17-base-pair inverted repeats, centered around -40 and -162. Sequences lying between -140 and -173 were important for efficient transcription since deletion of this region reduced the activity fourfold. Deletion of either one of the two inverted repeats or insertion of DNA fragments between them resulted in the synthesis of extra transcripts that initiated at sites upstream from the EIV site. The third region was located between -198 and -250 and contains three guanosine-plus-cytosine-rich sequences, present around -212 (GGGCGG), -233 (GGGCGG), and -251 (CGCGGG). The fourth, most upstream region was located between -260 and -307. Deletion of this region, which contains the NF-1 factor-binding site, slightly reduced transcriptional activity both in vivo and in vitro. The data indicate that multiple cis-acting elements are required for efficient transcription from the EIV promoter in both in vitro and in vivo systems.

Identification of two transcription factors that bind to specific elements in the promoter of the adenovirus early-region 4.

Two kinds of trans-acting factors that regulate transcription from the promoter of the adenovirus early-region 4 (E4) have been identified by reconstituting nuclear extracts of HeLa cells. They were designated E4TF1 and E4TF3 for E4 transcription factors. These factors were responsible for efficient and accurate transcription in vitro from the E4 promoter, as were another transcription factor, designated E4TF2, and a crude fraction containing endogenous RNA polymerase II. E4TF1 stimulated transcription from the E4 promoter but not from the major late promoter or the E4 mutant promoter lacking the E4TF1-binding site. Footprint analysis of E4TF1 revealed that it binds to a specific region, residing between 132 and 152 base pairs upstream from the initiation site of the E4 mRNA. E4TF3 also regulated transcription from the E4 promoter. E4TF3 protected four ca. 20-base-pair regions in a DNase I footprinting assay. They were located around 40, 160, 230, and 260 base pairs upstream from the initiation site of E4 mRNA. Specific inhibition of E4 transcription was observed by addition of DNA fragments covering one of the E4TF1- and E4TF3-binding sites to in vitro transcription assays. These results suggest that both E4TF1 and E4TF3 regulate E4 transcription by binding to the specific upstream elements in the E4 promoter. These factors may be involved in the E1A transactivation of E4 transcription.

Sequential transcription-translation of simian virus 40 by using mammalian cell extracts.

Ribonucleic acids (RNAs) transcribed in vitro by using the whole-cell extract system of Manley et al. (Proc. Natl. Acad. Sci. U.S.A. 77:3855-3859, 1980) were tested for their efficiency and fidelity in directing protein synthesis in reticulocyte lysates. Simian virus 40 deoxyribonucleic acid (DNA), cleaved by various restriction endonucleases, was used as the template. Successful translation of the small tumor antigen t, as well as the capsid proteins VP1, VP2, and VP3, was detected by immunoprecipitation analysis. Although no synthesis of large T antigen was detected, use of this technology allows detection of large T synthesis resulting from the correct splicing of as little as 0.2% of the in vitro RNA transcripts, making it ideal for use as an in vitro splicing assay. Transcripts synthesized in vitro were used as messages at least as efficiently as were viral messenger RNA's (mRNA's) synthesized in vivo; and in the case of small t, there was more efficient translation of small t mRNA synthesized in vitro than of small t mRNA synthesized in vivo. The transcripts that served as mRNA's for the various polypeptides were identified by using the following two criteria. (i) The sensitivity of synthesis of a given protein to digestion of the template DNA with restriction enzymes allowed the localization of the promoter and coding regions. (ii) Translation of size-fractionated RNA allowed confirmation of the transcript-mRNA assignments. With these techniques we found that VP2, VP3 and, in some cases, VP1 synthesis resulted from the initiation of translation at internal AUG codons. In fact, families of polypeptides were produced by initiation of translation at AUG codons within sequences coding for VP1 and T, presumably as a result of transcription initiation events that generated 5' ends immediately upstream from these AUGs. Application of this technology for the identification of coding regions within cloned DNA fragments is discussed.

Tat-SF1 protein associates with RAP30 and human SPT5 proteins.

The potent transactivator Tat recognizes the transactivation response RNA element (TAR) of human immunodeficiency virus type 1 and stimulates the processivity of elongation of RNA polymerase (Pol) II complexes. The cellular proteins Tat-SF1 and human SPT5 (hSPT5) are required for Tat activation as shown by immunodepletion with specific sera and complementation with recombinant proteins. In nuclear extracts, small fractions of both hSPT5 and Pol II are associated with Tat-SF1 protein. Surprisingly, the RAP30 protein of the heterodimeric transcription TFIIF factor is associated with Tat-SF1, while the RAP74 subunit of TFIIF is not coimmunoprecipitated with Tat-SF1. Overexpression of Tat-SF1 and hSPT5 specifically stimulates the transcriptional activity of Tat in vivo. These results suggest that Tat-SF1 and hSPT5 are indispensable cellular factors supporting Tat-specific transcription activation and that they may interact with RAP30 in controlling elongation.

cDNA cloning of transcription factor E4TF1 subunits with Ets and notch motifs.

E4TF1 was originally identified as one of the transcription factors responsible for adenovirus E4 gene transcription. It is composed of two subunits, a DNA binding protein with a molecular mass of 60 kDa and a 53-kDa transcription-activating protein. Heterodimerization of these two subunits is essential for the protein to function as a transcription factor. In this study, we identified a new E4TF1 subunit, designated E4TF1-47, which has no DNA binding activity but can associate with E4TF1-60. We then cloned the cDNAs for each of the E4TF1 subunits. E4TF1 was purified, and the partial amino acid sequence of each subunit was determined. The predicted amino acid sequence of each cDNA clone revealed that E4TF1-60 had an ETS domain, which is a DNA binding domain common to ets-related transcription factors. E4TF1-53 had four tandemly repeated notch-ankyrin motifs. The putative cDNA of E4TF1-47 coded almost the same amino acid sequences as E4TF1-53. Three hundred and thirty-two amino acids of the N termini of E4TF1-47 and -53 were identical except for one amino acid insertion in E4TF1-53, and they differ from each other at the C terminus. These three recombinant cDNA clones were expressed in Escherichia coli, and the proteins behaved in the same manner as purified proteins in a gel retardation assay. Nucleotide and predicted amino acid sequences were highly homologous to GABP-alpha and -beta, which is further supported by the observation that GABP-specific antibody can recognize human E4TF1.

Functional interference of Sp1 and NF-kappaB through the same DNA binding site.

Gene activation by NF-kappaB/Rel transcription factors is modulated by synergistic or antagonistic interactions with other promoter-bound transcription factors. For example, Sp1 sites are often found in NF-kappaB-regulated genes, and Sp1 can activate certain promoters in synergism with NF-kappaB through nonoverlapping binding sites. Here we report that Sp1 acts directly through a subset of NF-kappaB binding sites. The DNA binding affinity of Sp1 to these NF-kappaB sites, as determined by their relative dissociation constants and their relative efficiencies as competitor DNAs or as binding site probes, is in the order of that for a consensus GC box Sp1 site. In contrast, NF-kappaB does not bind to a GC box Sp1 site. Sp1 can activate transcription through immunoglobulin kappa-chain enhancer or P-selectin promoter NF-kappaB sites. p50 homodimers replace Sp1 from the P-selectin promoter by binding site competition and thereby either inhibit basal Sp1-driven expression or, in concert with Bcl-3, stimulate expression. The interaction of Sp1 with NF-kappaB sites thus provides a means to keep an elevated basal expression of NF-kappaB-dependent genes in the absence of activated nuclear NF-kappaB/Rel.

A nuclear factor (NF2d9) that binds to the male-specific P450 (Cyp 2d-9) gene in mouse liver.

Expression of the Cyp 2d-9 (steroid 16 alpha-hydroxylase) gene in mouse liver is male specific in such Mus musculus domesticus strains as FVB/N, whereas the corresponding P450 genes in the wild mouse species Mus spretus are not sex specific in their expression. These parental differences in the gene expressions were independently inherited in F1 offspring from crosses of FVB/N and M. spretus. A 5' flanking sequence (-110CTC CTCCCTATTCCGGGCC-92) was defined as a regulatory element (named SDI-A1) for the domestic Cyp 2d-9 promoter. The nucleotide which corresponds to T at position -99 within SDI-A1 was found to be substituted with C in the wild mouse P450 genes. The placing of C at position -99 abolished the transcriptional activity of SDI-A1 in HepG2 cells as well as the binding of SDI-A1 to a nuclear factor. This factor (designated NF2d9) was purified from mouse nuclear extracts, and its cDNA cloned. The purified NF2d9 bound to SDI-A1 but not to the mutated SDI-A1 with C at position -99. The deduced amino acid sequence revealed that NF2d9 is 72 and 94% identical to mouse CP2 and human LBP-1a, respectively. NF2d9 thus belongs to the CP2 family and is the mouse homolog of human LBP-1a, which modulates human immunodeficiency virus type 1 transcription. Anti-NF2d9, which was raised against the bacterially expressed protein, supershifted the SDI-A1 complex with the liver nuclear extract. Both the bacterially expressed and in vitro-translated NF2d9 inhibited SDI-A1 complex formation, although they did not bind to SDI-A1 directly. The results, therefore, indicate that the domestic Cyp 2d-9 gene can be regulated through a specific association of NF2d9 with SDI-A1.

High-performance affinity beads for identifying drug receptors.

We have developed a method using novel latex beads for rapid identification of drug receptors using affinity purification. Composed of a glycidylmethacrylate (GMA) and styrene copolymer core with a GMA polymer surface, the beads minimize nonspecific protein binding and maximize purification efficiency. We demonstrated their performance by efficiently purifying FK506-binding protein using FK506-conjugated beads, and found that the amount of material needed was significantly reduced compared with previous methods. Using the latex beads, we identified a redox-related factor, Ref-1, as a target protein of an anti-NF-kappaB drug, E3330, demonstrating the existence of a new class of receptors of anti-NF-kappaB drugs. Our results suggest that the latex beads could provide a tool for the identification and analysis of drug receptors and should therefore be useful in drug development.

Dioxin-like activity of brominated dioxins as individual compounds or mixtures in in vitro reporter gene assays with rat and mouse hepatoma cell lines.

In vitro reporter gene assays detecting dioxin-like compounds have been developed and validated since the middle 1990's, and applied to the determination of dioxin-like activities in various samples for their risk management. Data on characterizing the potency of individual brominated dioxins and their activity in mixture with chlorinated dioxins are still limited on the cell-based assay. This study characterized the dioxin-like activities of the 32 brominated dioxins, such as polybrominated dibenzo-p-dioxins, polybrominated dibenzofurans (PBDFs), coplanar polybrominated biphenyls, mixed halogenated dibenzo-p-dioxins and dibenzofurans (PXDFs), as a sole component or in a mixture by DR-CALUX (dioxin-responsive chemically activated luciferase expression) using the rat hepatoma H4IIE cell line and XDS-CALUX (xenobiotic detection systems-chemically activated luciferase expression) assays using the mouse hepatoma H1L6.1 cell line. The 2,3,7,8-TCDD-relative potencies (REPs) of most of the brominated dioxins were within a factor of 10 of the WHO toxicity equivalency factor (WHO-TEF) for the chlorinated analogues. The REPs of a few PXDFs were an order of magnitude higher than the corresponding WHO-TEFs, indicating their toxicological importance. Results with reconstituted mixtures suggest that the activity of brominated and chlorinated dioxins in both CALUX assays was dose-additive. Thus, obtained results indicated the applicability of the CALUX assays as screening tools of brominated dioxins together with their chlorinated analogues.

A small-scale, rolled-membrane microfluidic artificial lung designed towards future large area manufacturing.

Artificial lungs have been used in the clinic for multiple decades to supplement patient pulmonary function. Recently, small-scale microfluidic artificial lungs (µAL) have been demonstrated with large surface area to blood volume ratios, biomimetic blood flow paths, and pressure drops compatible with pumpless operation. Initial small-scale microfluidic devices with blood flow rates in the µl/min to ml/min range have exhibited excellent gas transfer efficiencies; however, current manufacturing techniques may not be suitable for scaling up to human applications. Here, we present a new manufacturing technology for a microfluidic artificial lung in which the structure is assembled via a continuous "rolling" and bonding procedure from a single, patterned layer of polydimethyl siloxane (PDMS). This method is demonstrated in a small-scale four-layer device, but is expected to easily scale to larger area devices. The presented devices have a biomimetic branching blood flow network, 10 µm tall artificial capillaries, and a 66 µm thick gas transfer membrane. Gas transfer efficiency in blood was evaluated over a range of blood flow rates (0.1-1.25 ml/min) for two different sweep gases (pure O2, atmospheric air). The achieved gas transfer data closely follow predicted theoretical values for oxygenation and CO2 removal, while pressure drop is marginally higher than predicted. This work is the first step in developing a scalable method for creating large area microfluidic artificial lungs. Although designed for microfluidic artificial lungs, the presented technique is expected to result in the first manufacturing method capable of simply and easily creating large area microfluidic devices from PDMS.

Vertebrate TBP-like protein (TLP/TRF2/TLF) stimulates TATA-less terminal deoxynucleotidyl transferase promoters in a transient reporter assay, and TFIIA-binding capacity of TLP is required for this function.

The TBP-like protein (TLP/TRF2/TLF), which belongs to the TBP family of proteins, is present in all metazoan organisms. Although the human TLP has been reported to interfere with transcription from TATA-containing promoters, the transcription activation potential of TLP in higher animals is obscure. We previously demonstrated that artificially promoter-recruited TLP behaves like an unconventional transcriptional activator. In this study, we investigated the effects of TLP on TATA-less promoters of mouse and human terminal deoxynucleotidyl transferase (TdT) genes by transient reporter assays. As expected, TLP repressed both basal and activator-augmented transcription from the TATA-containing adenovirus major late promoter (MLP) and E1B promoter. On the other hand, however, TLP significantly stimulated both basal and activated transcription from TdT promoters. We investigated the strength of the promoters in chicken DT40 cells that lack the TLP gene. The MLP showed higher activity but the TdT promoter showed lower activity in TLP-null cells than in the wild-type cells. Moreover, ectopic expression of mouse TLP in the TLP-null cells considerably stimulated the TdT promoter. Insertion of a TATA element upstream from the TdT core promoter resulted in a loss of TLP-mediated activation. The mouse TLP was demonstrated to bind specifically to TFIIA with greater strength than TBP. We constructed mutated TLPs having amino acid substitutions that impair TFIIA binding. A representative TLP mutant lacking TFIIA-binding ability could not stimulate transcription from the TdT promoter, whereas that mutation suppressed TLP-mediated transcription repression of TATA promoters. The results of the present study suggest that the vertebrate TLP potentiates exogenous TATA-less promoters and that TFIIA plays an important role in the TLP function.

Specific adoptive immunotherapy with tumor-specific cytotoxic T-lymphocyte clone for murine malignant gliomas.

The efficacy of glioma-specific cytotoxic T-lymphocyte for a syngeneic murine malignant glioma (a 20-methylcholanthrene-induced ependymoblastoma, 203-glioma) was investigated. The cytotoxic clone (G-CTLL 1), established and expanded exponentially by T-cell growth factor, has retained target specificity for more than 6 months. In adoptive therapy and Winn assay, the in vivo antitumor activity of G-CTLL 1 was demonstrated against mice inoculated intracranially with 203-glioma cells. The therapeutic effects in adoptive immunotherapy were largely dependent on dose and time of i.v. administration, although the therapy was rather ineffective in condition of increased intracranial pressure due to the tumor growth. The mechanisms responsible for the in vivo protection were probably related to the killing activity of G-CTLL 1 or the tumor-specific production of immune interferon by G-CTLL 1.

Characteristic immunological responses to an experimental mouse brain tumor.

Immunological responses to an experimental brain tumor of mice [the 20-methylcholanthrene-induced malignant glioma, 203-glioma)] were investigated. The killer T-cell activity of spleen cells, which was specific against 203-glioma cells, began to be severely impaired 2 weeks after intracranial inoculation; this impairment was concurrent with increased intracranial pressure, which was due to developing tumor growth. On the other hand, the killer T-cell activity continued for over 4 weeks in mice inoculated with the mitomycin C-treated tumor cells. Surface marker analysis showed that Lyt-1-2,3+ killer T-cells were predominant in intracranial tumor-bearing mice, whereas both Lyt-1-,2,3+ and Lyt-1+,2,3+ killer T-cells were equally present in s.c. tumor-bearing mice. The effects of adult thymectomy on the immune responses against 203-glioma were also investigated in intracranial and s.c. tumor-bearing mice. In both the intracranially and s.c. inoculated groups, killer T-cell activity was increased in mice thymectomized before 3 weeks and decreased in mice thymectomized before 10 weeks. In these mice, Lyt-1+,2,3+ killer T-cells were not detected, which suggests strongly that the progenitors of Lyt-1+,2,3+ killer T-cells are short-lived lymphocytes in contrast to those of Lyt-1-,2,3+ killer T-cells, which survive more than 10 weeks after adult thymectomy.

Immunoregulatory effects of interleukin 2 and interferon on syngeneic murine malignant glioma-specific cytotoxic T-lymphocytes.

The effects of interleukin 2 (IL2) and interferon (IFN) on the generation and lytic activation of syngeneic murine malignant glioma (a methylcholanthrene-induced ependymoblastoma of C57BL/6 mouse origin, 203-glioma)-specific cytotoxic T-lymphocyte (G-CTL) were investigated. The surface marker analysis showed that G-CTLs from both intracranial and s.c. tumor-bearing mice were composed of thymectomy-resistant (mature) Lyt-1-.2.3+ and thymectomy-sensitive (immature) Lyt-1+.2.3+ CTLs, which markedly decreased concurrently with increased intracranial pressure. G-CTLs were confirmed to be activated with target specificity by both factors in a different way. The CTL activation by IL2 (20 units/ml) remained for a longer time, although a lag time of 5 days after initial culture was required. IL2 influenced Lyt-1+.2.3+ CTLs to proliferate and develop the lytic potential. In contrast, even a 3-h incubation with IFN (1000 units/ml) could enhance the cytotoxicity, but the augmenting effects were observed no longer than 5 days later. IFN activated Lyt-1-.2.3+ CTLs and increased their proportion of the total cell population with a simultaneous decrease of Lyt-1+.2.3+ CTLs. Therefore, it was suggested that IL2 may provide a growth of CTL populations and that IFN can accelerate recruitment of new effectors, causing activation of the lytic process.

Retinoblastoma binding factor 1 site in the core promoter region of the human RB gene is activated by hGABP/E4TF1.

We previously reported two oncogenic point mutations present in the RB (retinoblastoma) gene promoter region, found at consensus Sp1 and ATF sites, respectively, and in two separate hereditary RB families. However, Sp1 protein was shown not to bind to the Sp1 site; this indicated that the Sp1 consensus site mutation was blocking the action of an alternative transcription factor, which we called RBF-1 (retinoblastoma binding factor 1). Subsequent purification of RBF-1 revealed it to be hGABP/E4TF1, a transactivator from the adenovirus early-region 4 promoter. In this study, we directly examined the effects of hGABP/E4TF1 on transactivation of the RB gene promoter through the RBF-1 site. As expected, hGABP/E4TF1 enhanced the core RB promoter activity, whereas it did not stimulate a mutant RBF-1 site. We therefore conclude that the most essential transcription factor in the human RB gene is likely to be hGABP/E4TF1.

ZEB1 induces EPB41L5 in the cancer mesenchymal program that drives ARF6-based invasion, metastasis and drug resistance.

Onset of the cancer mesenchymal program is closely associated with cancer malignancy and drug resistance. Among the different epithelial-mesenchymal transition (EMT)-associated transcriptional factors, ZEB1 has a key role in inducing the mesenchymal phenotypes and stem cell-like properties of different breast cancer cells. ARF6 and its effector AMAP1 are frequently overexpressed in breast cancer cells, and promote invasion, metastasis and drug resistance. EPB41L5 is induced during EMT, and mediates the disruption of E-cadherin-based cell-cell adhesion and the promotion of focal adhesion dynamics. Here we show that EPB41L5 is an integral component of the ARF6-based pathway, which is induced by ZEB1. We found that EPB41L5 is expressed at high levels in malignant breast cancer cells and binds to AMAP1. ZEB1 induced EPB41L5 both in cancer cells and normal cells. This relationship was recaptured with The Cancer Genome Atlas RNASeq data set, and correlated with the poor outcome of the patients. In contrast, diversified events, such as tumor growth factor ß1 stimulation, expression of SNAI1 and TP53 mutation, can each cause the induction of ZEB1 and EPB41L5, depending on the cellular context. Our results demonstrated that the ZEB1-EPB41L5 axis is at the core of the cancer mesenchymal program that drives ARF6-based invasion, metastasis and drug resistance of significant populations of primary breast cancers, and is tightly correlated with the poor outcomes of patients.