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Analytical studies of the results of thermal imaging control using IAS TIK together with the corresponding values of the temperature control results obtained in the standard DGS condition monitoring system were carried out within the framework of R&D for the development of an integrated automated system for thermal imaging control (IAS TIK). Approbation of IAS TIK in NPP conditions was carried out by thermography of standby diesel generator sets of NPP type 12zv40/48+S2445-12. At the same time, the parameters of the diesel engine and the generator were measured using the standard control system. The methodology is proposed that provides an analysis of the uniformity of the operation of diesel cylinders, the condition of the crankshaft bearings, the condition and quality of the generated electricity of the generator, as well as the analysis of the operation of lubrication and cooling systems. The practical application of the technique demonstrates the correspondence between the temperatures measured by the standard system and the IAS TIK. A joint analysis of the results obtained by the standard and developed systems provides an increase in the depth of the diagnostic examination and confirms the information content of the thermographic parameters and the quality of the measurement channels of the standard systems. The parameter values obtained from the analysis of the indicators of the standard control system, recorded at a steady power value, will be used in subsequent diagnostics to establish trends in these parameters

Multimodal treatment has improved the outcome of many solid tumors, and in some cases the use of radiosensitizers has significantly contributed to this gain. Activation of the extracellular signaling kinase pathway (MEK/ERK) generally results in stimulation of cell growth and confers a survival advantage playing the major role in human cancer. The potential involvement of this pathway in cellular radiosensitivity remains unclear. We previously reported that the disruption of c-Myc through MEK/ERK inhibition blocks the expression of the transformed phenotype; affects in vitro and in vivo growth and angiogenic signaling; and induces myogenic differentiation in the embryonal rhabdomyosarcoma (ERMS) cell lines (RD). This study was designed to examine whether the ERK pathway affects intrinsic radiosensitivity of rhabdomyosarcoma cancer cells. Exponentially growing human ERMS, RD, xenograft-derived RD-M1, and TE671 cell lines were used. The specific MEK/ERK inhibitor, U0126, reduced the clonogenic potential of the three cell lines, and was affected by radiation. U0126 inhibited phospho-active ERK1/2 and reduced DNA protein kinase catalytic subunit (DNA-PKcs) suggesting that ERKs and DNA-PKcs cooperate in radioprotection of rhabdomyosarcoma cells. The TE671 cell line xenotransplanted in mice showed a reduction in tumor mass and increase in the time of tumor progression with U0126 treatment associated with reduced DNA-PKcs, an effect enhanced by radiotherapy. Thus, our results show that MEK/ERK inhibition enhances radiosensitivity of rhabdomyosarcoma cells suggesting a rational approach in combination with radiotherapy. Mol Cancer Ther; 10(1); 159–68. ©2011 AACR.

Supplementary Figure 6 from MEK/ERK Inhibitor U0126 Increases the Radiosensitivity of Rhabdomyosarcoma Cells In vitro and In vivo by Downregulating Growth and DNA Repair Signals

Supplementary Figure 3 from MEK/ERK Inhibitor U0126 Increases the Radiosensitivity of Rhabdomyosarcoma Cells In vitro and In vivo by Downregulating Growth and DNA Repair Signals

In Arruda (On the imaginary logic of N.A.Vasiliev. In: Proceedings of fourth Latin-American symposium on mathematical logic, pp 1–41, 1979) presented calculi in order to formalize some ideas of N.A. Vasiliev. Calculus V1 is one of the calculi in question. Vasiliev fragment of the logic definable with A. Arruda’s calculus V1 (that is, a set of all V1-provable formulas with the following property: each propositional variable occurring in a formula is a Vasiliev propositional variable) is of independent interest. It should be noted that the fragment in question is equal to the logic definable with calculus P 1 in Sette (Math Jpn 18(3):173–180, 1973). In our paper, (a) we define logics I 1,1, I 1,2, I 1,3, … I 1,ω (see Popov (Two sequences of simple paraconsistent logics. In: Logical investigations, vol 14-M., pp 257–261, 2007a (in Russian))), which form (in the order indicated above) a strictly decreasing (in terms of the set-theoretic inclusion) sequence of sublogics in Vasiliev fragment of the logic definable with A. Arruda’s calculus V1, (b) for any j in {1, 2, 3,…ω}, we present a sequent-style calculus GI 1,j (see Popov (Sequential axiomatization of simple paralogics. In: Logical investigations, vol 15, pp 205–220, 2010a. IPHRAN. M.-SPb.: ZGI (in Russian))) and a natural deduction calculus NI 1,j (offered by Shangin) which axiomatizes logic I 1,j , (c) for any j in {1, 2, 3,…ω}, we present an I 1,j -semantics (built by Popov) for logic I 1,j , (d) for any j in {1, 2, 3,…}, we present a cortege semantics for logic I 1,j (see Popov (Semantical characterization of paraconsistent logics I1,1, I1,2, I1,3,…. In: Proceedings of XI conference “modern logic: theory and applications”, Saint-Petersburg, 24–26 June. SPb, pp 366–368, 2010b (in Russian))). Below there are some results obtained with the presented semantics and calculi.

Cancer stem cells (CSCs) possess the capacity to self-renew and to generate heterogeneous lineages of cancer cells that comprise tumors. A substantial body of evidence supports a model in which CSCs play a major role in the initiation, maintenance, and clinical outcome of cancers. In contrast, analysis of the role of CSCs in metastasis has been mainly conceptual and speculative. This review summarizes recent data that support the theory of CSCs as the source of metastatic lesions in breast cancer, with a focus on the key role of the microenvironment in the stemness-metastasis link.

Acetylation is an essential post-translational modification featuring an acetyl group that is covalently conjugated to a protein substrate. Histone acetylation was first proposed nearly half a century ago by Dr. Vincent Allfrey. Subsequent studies have shown that the acetylated core histones are often associated with transcriptionally active chromatin. Acetylation at lysine residues of histone tails neutralizes the positive charge, which decreases their binding ability to DNA and increases the accessibility of transcription factors and coactivators to the chromatin template. In addition to histones, a number of non-histone substrates are acetylated. Acetylation of non-histone proteins governs biological processes, such as cellular proliferation and survival, transcriptional activity, and intracellular trafficking. We demonstrated that acetylation of transcription factors can regulate cellular growth. Furthermore, we showed that nuclear receptors (NRs) are acetylated at a phylogenetically conserved motif. Since our initial observations with the estrogen and androgen receptors, more than a dozen NRs have been shown to function as substrates for acetyltransferases with diverse functional consequences. This review focuses on the acetylation of NRs and the effect of acetylation on NR function. We discuss the potential role of acetylation in disease initiation and progression with an emphasis on tumorigenesis.

DACH1 (Dachshund homolog 1) is a key component of the retinal determination gene network and regulates gene expression either indirectly as a co-integrator or through direct DNA binding. The current studies were conducted to understand, at a higher level of resolution, the mechanisms governing DACH1-mediated transcriptional repression via DNA sequence-specific binding. DACH1 repressed gene transcription driven by the DACH1-responsive element (DRE). Recent genome-wide ChIP-Seq analysis demonstrated DACH1 binding sites co-localized with Forkhead protein (FOX) binding sites. Herein, DACH1 repressed, whereas FOX proteins enhanced, both DRE and FOXA-responsive element-driven gene expression. Reduced DACH1 expression using a shRNA approach enhanced FOX protein activity. As DACH1 antagonized FOX target gene expression and attenuated FOX signaling, we sought to identify limiting co-integrator proteins governing DACH1 signaling. Proteomic analysis identified transcription elongation regulator 1 (TCERG1) as the transcriptional co-regulator of DACH1 activity. The FF2 domain of TCERG1 was required for DACH1 binding, and the deletion of FF2 abolished DACH1 trans-repression function. The carboxyl terminus of DACH1 was necessary and sufficient for TCERG1 binding. Thus, DACH1 represses gene transcription through direct DNA binding to the promoter region of target genes by recruiting the transcriptional co-regulator, TCERG1.

The Drosophila Dachshund ( Dac ) gene, cloned as a dominant inhibitor of the hyperactive growth factor mutant ellipse , encodes a key component of the retinal determination gene network that governs cell fate. Herein, cyclic amplification and selection of targets identified a DACH1 DNA-binding sequence that resembles the FOX ( F orkhead b ox –containing protein) binding site. Genome-wide in silico promoter analysis of DACH1 binding sites identified gene clusters populating cellular pathways associated with the cell cycle and growth factor signaling. ChIP coupled with high-throughput sequencing mapped DACH1 binding sites to corresponding gene clusters predicted in silico and identified as weight matrix resembling the cyclic amplification and selection of targets–defined sequence. DACH1 antagonized FOXM1 target gene expression, promoter occupancy in the context of local chromatin, and contact-independent growth. Attenuation of FOX function by the cell fate determination pathway has broad implications given the diverse role of FOX proteins in cellular biology and tumorigenesis.

The (HER2/Neu) ErbB2 oncogene is commonly overexpressed in human breast cancer and is sufficient for mammary tumorigenesis in transgenic mice. Nuclear factor (NF)-kappaB activity is increased in both human and murine breast tumors. The immune response to mammary tumorigenesis may regulate tumor progression. The role of endogenous mammary epithelial cell NF-kappaB had not previously been determined in immune-competent animals. Furthermore, the role of the NF-kappaB components, p50 and p65, in tumor growth was not known. Herein, the expression of a stabilized form of the NF-kappaB-inhibiting IkappaBalpha protein (IkappaBalphaSR) in breast tumor cell lines that express oncogenic ErbB2 inhibited DNA synthesis and growth in both two- and three-dimensional cultures. Either NF-kappaB inhibition or selective silencing of p50 or p65 led to a loss of contact-independent tumor growth in vitro. IkappaBalphaSR reversed the features of the oncogene-induced phenotype under three-dimensional growth conditions. The NF-kappaB blockade inhibited ErbB2-induced mammary tumor growth in both immune-competent and immune-deficient mice. These findings were associated with both reduced tumor microvascular density and a reduction in the amount of vascular endothelial growth factor. The expression of IkappaBalphaSR in breast cancer tumors inhibited angiogenesis. Thus, mammary epithelial cell NF-kappaB activity enhances ErbB2-mediated mammary tumorigenesis in vivo by promoting both growth and survival signaling via the promotion of tumor vasculogenesis.

The PC12 pheochromocytoma cell line responds to nerve growth factor (NGF) by exiting from the cell cycle and differentiating to induce extending neurites. Cyclin D1 is an important regulator of G1/S phase cell cycle progression, and it is known to play a role in myocyte differentiation in cultured cells. Herein, NGF induced cyclin D1 promoter, mRNA, and protein expression via the p21RASpathway. Antisense- or small interfering RNA to cyclin D1 abolished NGF-mediated neurite outgrowth, demonstrating the essential role of cyclin D1 in NGF-mediated differentiation. Expression vectors encoding mutants of the Ras/mitogen-activated protein kinase pathway, and chemical inhibitors, demonstrated NGF induction of cyclin D1 involved cooperative interactions of extracellular signal-regulated kinase, p38, and phosphatidylinositol 3-kinase pathways downstream of p21RAS. NGF induced the cyclin D1 promoter via Sp1, nuclear factor-κB, and cAMP-response element/activated transcription factor sites. NGF induction via Sp1 involved the formation of a Sp1/p50/p107 complex. Cyclin D1 induction by NGF governs differentiation and neurite outgrowth in PC12 cells.

Oncogene-mediated signaling to the host environment induces a subset of cytokines and chemokines. TheDrosophila Dacgene promotes migration of the morphogenetic furrow during eye development. Expression of the cell-fate determination factorDachshund(DACH1) was lost in poor prognosis invasive breast cancer. Mouse embryo fibroblasts derived fromDach1−/−mice demonstrated endogenousDach1constitutively represses cellular migration. DACH1 inhibited cellular migration and invasion of oncogene (Ras, Myc, ErbB2, c-Raf)-transformed human breast epithelial cells. An unbiased proteomic analysis identified and immunoneutralizing antibody and reconstitution experiments demonstrated IL-8 is a critical target of DACH1 mediating breast cancer cellular migration and metastasisin vivo. DACH1 bound the endogenousIL-8promoter in ChIP assays and repressed theIL-8promoter through the AP-1 and NF-κB binding sites. Collectively, our data identify a pathway by which an endogenous cell-fate determination factor blocks oncogene-dependent tumor metastasis via a key heterotypic mediator.

The position effect variegation in Drosophila and Schizosaccharomyces pombe, and higher-order chromatin structure regulation in yeast, is orchestrated by modifier genes of the Su(var) group, (e.g., histone deacetylases ([HDACs]), protein phosphatases) and enhancer E(Var) group (e.g., ATP [adenosine 5'-triphosphate]-dependent nucleosome remodeling proteins). Higher-order chromatin structure is regulated in part by covalent modification of the N-terminal histone tails of chromatin, and histone tails in turn serve as platforms for recruitment of signaling modules that include nonhistone proteins such as heterochromatin protein (HP1) and NuRD. Because the enzymes governing chromatin structure through covalent modifications of histones (acetylation, methylation, phosphorylation, ubiquitination) can also target nonhistone substrates, a mechanism is in place by which epigenetic regulatory processes can affect the function of these alternate substrates. The posttranslational modification of histones, through phosphorylation and acetylation at specific residues, alters chromatin structure in an orchestrated manner in response to specific signals and is considered the basis of a "histone code." In an analogous manner, specific residues within transcription factors form a signaling module within the transcription factor to determine genetic target specificity and cellular fate. The architecture of these signaling cascades in transcription factors (SCITs) are poorly understood. The regulation of estrogen receptor (ERalpha) by enzymes that convey epigenetic signals is carefully orchestrated and is reviewed here.

A group of several methods for detailed investigation of electrically active defects (EAD) and their properties in insulator-semiconductor (IS) and metal-insulator-semiconductor (MIS) structures has been developed. It consists of different ways of analyzing EAD including precision measurements of local electrophysical properties of IS structures, mapping of defects in IS structures by means of nematic liquid crystals (NLC), application of scanning electron microscopy (SEM) in electron beam induced current (EBIC) mode for localization of EAD in the semiconductor of MIS structures. Local electrophysical measurements are carried out by using dynamic unsteady-state current–voltage characteristics (DUCVC) and their modifications which have higher sensitivity to detection of generation processes in MIS structures as compared with ordinary capacitance–voltage characteristics. Depth distributions of bulk generation lifetime of minority carriers in semiconductors, obtained by the DUCVC method, reflect normalized EAD profiles near the IS interface. The NLC method is nondestructive and makes possible to analyze lateral distribution of defects with high local conductivity in insulating films. It was shown that in the case of thin SiO2 films on silicon EAD at semiconductor surface are also revealed by the NLC method. As a result determination of EAD coordinates opens possibility for further detailed investigation of separate EAD properties by the DUCVC method using local mercury probe 5 μm in size. Special MIS gated p–n junctions have been used for mapping of EAD with high recombination velocity in semiconductor under the metal or polysilicon gates. Combination of the described methods was applied for investigation of local EAD properties of Si-based structures, which are used for fabrication of integrated circuits. The influence of gettering on EAD concentration in Si and SiO2 has been investigated.

The molecular mechanisms by which glioblastoma multiforme (GBM) refracts and becomes resistant to radiotherapy treatment remains largely unknown. This radioresistance is partly due to the presence of hypoxic regions, which are frequently found in GBM tumors. We investigated the radiosensitizing effects of MEK/ERK inhibition on GBM cell lines under hypoxic conditions. Four human GBM cell lines, T98G, U87MG, U138MG and U251MG were treated with the MEK/ERK inhibitor U0126, the HIF-1α inhibitor FM19G11 or γ-irradiation either alone or in combination under hypoxic conditions. Immunoblot analysis of specific proteins was performed in order to define their anti‑oncogenic or radiosensitizing roles in the different experimental conditions. MEK/ERK inhibition by U0126 reverted the transformed phenotype and significantly enhanced the radiosensitivity of T98G, U87MG, U138MG cells but not of the U251MG cell line under hypoxic conditions. U0126 and ERK silencing by siRNA reduced the levels of DNA protein kinase catalytic subunit (DNA-PKcs), Ku70 and K80 proteins and clearly reduced HIF-1α activity and protein expression. Furthermore, DNA-PKcs siRNA-mediated silencing counteracted HIF-1α activity and downregulated protein expression suggesting that ERKs, DNA-PKcs and HIF-1α cooperate in radioprotection of GBM cells. Of note, HIF-1α inhibition under hypoxic conditions drastically radiosensitized all cell lines used. MEK/ERK signal transduction pathway, through the sustained expression of DNA-PKcs, positively regulates HIF-1α protein expression and activity, preserving GBM radioresistance in hypoxic condition.

Chronic radiation cystitis (CRC) is a serious complication that can arise in patients with pelvic malignancies treated with radiotherapy. Polydeoxyribonucleotides (PDRNs) are known to reduce inflammation and improve tissue perfusion and angiogenesis. In this manuscript, we describe our observational experience regarding intravesical instillation of PDRNs in improving symptoms of CRC in subjects unresponsiveness to conventional medical therapy.Eight patients with persistent and/or worsening CRC symptoms, despite conventional therapy, received biweekly intravesical instillation of PDRNs for two consecutive months. Symptoms were scored according to the Late Effects of Normal Tissues-Subjective, Objective, Management, Analytic (LENT-SOMA) scale, before, at the end, and after 4 months following the PDRNs treatment.Four months after instillations, a significant improvement in the subjective perception of CRC symptoms was experienced by participants. The mean LENT-SOMA score was reduced from 1.16+0.26 before to 0.34+0.035 after 4 months from instillations (p0.001). No adverse effect related to instillations was reported.Subjective perception of persistent and/or worsening CRC symptoms, despite conventional therapy, is improved after intravesical instillation with PDRNs without adverse events. Even though we deduced suggestive insights, the results need to be collected and verified from a large-scale study.

Prostate cancer (Pca) is a heterogeneous disease; its etiology appears to be related to genetic and epigenetic factors. Radiotherapy and hormone manipulation are effective treatments, but many tumors will progress despite these treatments. Molecular imaging provides novel opportunities for image-guided optimization and management of these treatment modalities. Here we reviewed the advances in targeted imaging of key biomarkers of androgen receptor signaling pathways. A computerized search was performed to identify all relevant studies in Medline up to 2013. There are well-known limitations and inaccuracies of current imaging approaches for monitoring biological changes governing tumor progression. The close integration of molecular biology and clinical imaging could ease the development of new molecular imaging agents providing novel tools to monitor a number of biological events that, until a few years ago, were studied by conventional molecular assays. Advances in translational research may represent the next step in improving the oncological outcome of men with Pca who remain at high risk for systemic failure. This aim may be obtained by combining the anatomical properties of conventional imaging modalities with biological information to better predict tumor response to conventional treatments.

ObjectiveThis study aimed to determine the functional relationship between the levels of dachshund homolog 1 (DACH1) expression and different subtypes of ovarian cancer and to investigate the possible prognostic value of DACH1 in ovarian cancer.MethodsImmunohistochemical staining was deployed to determine the protein levels of DACH1. Staining was performed on patient samples, for whom the detailed follow-up data have been acquired during the last 10 years. Normal, benign, borderline, cancer, and metastatic ovarian cancer samples were included in this study.ResultsThe results of our study show that DACH1 protein levels increase with the invasiveness of the ovarian cancer. As the cancer progresses from benign and borderline to metastatic, DACH1 protein expression increases as well. Moreover, with the increase in expression, the subcellular distribution of DACH1 changes from nucleus in normal tissue to cytoplasm in cancer. Finally, DACH1 expression levels were compared with estrogen receptor α (ERα) levels, and the results showed that overall DACH1 levels were higher, whereas also DACH1 exhibited increased cytoplasmic expression in ERα-positive ovarian cancer samples.ConclusionsThese results indicate that DACH1 is highly expressed in metastatic ovarian cancer compared with that of normal, benign, and borderline ovarian tissues and that it could play an important role in cancer growth.

We hypothesized that hormonal therapy favors the development of the hormone-resistant phenotype through epigenetic mechanisms. Human prostate cancer tissues and in vitro and in vivo models were used to verify this hypothesis. We demonstrated that tumor cells continuously treated with bicalutamide (BCLT) or cultured in androgen-depleted medium progressively acquire higher DNA methyltransferase (DNMT) activity and expression than cells cultured in standard condition. Increased DNMT expression and activity also paralleled the up-regulation of truncated AR isoforms, which favors the development of the hormone-resistant phenotype. After androgen stimulation with 10−12m dihydrotestosterone, DNMT activity was significantly reduced in comparison with hormonal therapy. Consistent with these observations, the silencing of DNMT3a and DNMT3b significantly decreased the DNMT activity levels. These findings were also directly correlated with phosphatase and tensin homolog down-regulation and activation of ERK and phosphatidylinositol 3-kinases/AKT8 virus oncogene cellular homolog pathways. The use of a pan-DNMT inhibitor (5-Azacitidine) greatly reduced the development of the hormone-resistant phenotype induced by long-term BCLT treatment, and this finding correlated with low DNMT activity. The regulation of DNMT activity was, in some measure, dependent on the androgen receptor, as small interfering RNA treatment targeting the androgen receptor greatly decreased the modulation of DNMT activity under androgenic and antiandrogenic stimulation. These observations were correlated in vivo in patients, as demonstrated by immunohistochemistry. Patients treated by BCLT before surgery had higher DNMT3a and DNMT3b expression than patients who had not undergone this treatment. Our findings provide evidence of a relationship between the castration-resistant phenotype and DNMT expression and activity in human prostate cancer.

Multimodal treatment has improved the outcome of many solid tumors, and in some cases the use of radiosensitizers has significantly contributed to this gain. Activation of the extracellular signaling kinase pathway (MEK/ERK) generally results in stimulation of cell growth and confers a survival advantage playing the major role in human cancer. The potential involvement of this pathway in cellular radiosensitivity remains unclear. We previously reported that the disruption of c-Myc through MEK/ERK inhibition blocks the expression of the transformed phenotype; affects in vitro and in vivo growth and angiogenic signaling; and induces myogenic differentiation in the embryonal rhabdomyosarcoma (ERMS) cell lines (RD). This study was designed to examine whether the ERK pathway affects intrinsic radiosensitivity of rhabdomyosarcoma cancer cells. Exponentially growing human ERMS, RD, xenograft-derived RD-M1, and TE671 cell lines were used. The specific MEK/ERK inhibitor, U0126, reduced the clonogenic potential of the three cell lines, and was affected by radiation. U0126 inhibited phospho-active ERK1/2 and reduced DNA protein kinase catalytic subunit (DNA-PKcs) suggesting that ERKs and DNA-PKcs cooperate in radioprotection of rhabdomyosarcoma cells. The TE671 cell line xenotransplanted in mice showed a reduction in tumor mass and increase in the time of tumor progression with U0126 treatment associated with reduced DNA-PKcs, an effect enhanced by radiotherapy. Thus, our results show that MEK/ERK inhibition enhances radiosensitivity of rhabdomyosarcoma cells suggesting a rational approach in combination with radiotherapy. Mol Cancer Ther; 10(1); 159–68. ©2011 AACR.

Epigenetic modifications play a key role in the patho-physiology of many tumors and the current use of agents targeting epigenetic changes has become a topic of intense interest in cancer research. DNA methyltransferase (DNMT) inhibitors represent a promising class of epigenetic modulators. Research performed yielded promising anti-tumorigenic activity for these agents in vitro and in vivo against a variety of hematologic and solid tumors. These epigenetic modulators cause cell cycle and growth arrest, differentiation and apoptosis. Rationale for combining these agents with cytotoxic therapy or radiation is straightforward since the use of DNMT inhibitor offers greatly improved access for cytotoxic agents or radiation for targeting DNA-protein complex. The positive results obtained with these combined approaches in preclinical cancer models demonstrate the potential impact DNMT inhibitors may have in treatments of different cancer types. Therefore, as the emerging interest in use of DNMT inhibitors as a potential chemo- or radiation sensitizers is constantly increasing, further clinical investigations are inevitable in order to finalize and confirm the consistency of current observations. The present article will provide a brief review of the biological significance and rationale for the clinical potential of DNMT inhibitors in combination with other chemotherapeutics or ionizing radiation. The molecular basis and mechanisms of action for these combined treatments will be discussed herein.

The dachshund (dac) gene was initially described as a mutant phenotype in flies featuring extremely short legs relative to their body length. Functioning as a dominant suppressor of the ellipse mutation, a hypermorphic allele of the Epidermal Growth Factor Receptor (EGFR), the dac gene plays a key role in metazoan development, regulating ocular, limb, brain, and gonadal development. In the Drosophila eye, dac is a key component of the Retinal Determination Gene Network (RDGN) governing the normal initiation of the morphogenetic furrow and thereby eye development. Recent studies have demonstrated an important role for human Dachshund homologue (DACH1) in tumorigenesis, in particular, breast, prostate and ovarian cancer. The molecular mechanisms by which DACH1 regulates differentiation and tumorigenesis are discussed herein.

The Dachshund (dac) gene, initially cloned as a dominant inhibitor of the Drosophila hyperactive EGFR mutant ellipse, encodes a key component of the cell fate determination pathway involved in Drosophila eye development. Analysis of more than 2,200 breast cancer samples showed improved survival by some 40 months in patients whose tumors expressed DACH1. Herein, DACH1 and estrogen receptor-α (ERα) expressions were inversely correlated in human breast cancer. DACH1 bound and inhibited ERα function. Nuclear DACH1 expression inhibited estradiol (E2)-induced DNA synthesis and cellular proliferation. DACH1 bound ERα in immunoprecipitation-Western blotting, associated with ERα in chromatin immunoprecipitation, and inhibited ERα transcriptional activity, requiring a conserved DS domain. Proteomic analysis identified proline, glutamic acid, and leucine rich protein 1 (PELP1) as a DACH1-binding protein. The DACH1 COOH terminus was required for binding to PELP1. DACH1 inhibited induction of ERα signaling. E2 recruited ERα and disengaged corepressors from DACH1 at an endogenous ER response element, allowing PELP1 to serve as an ERα coactivator. DACH1 expression, which is lost in poor prognosis human breast cancer, functions as an endogenous inhibitor of ERα function. [Cancer Res 2009;69(14):5752–60]

Hormones were previously known to induce kinase signaling cascades from the cell surface to thenucleus.Nuclear receptors (NR) coordinate diversebiologicalphenotypes altering cellular metabolism, differentiation and cellular proliferation. The genes that regulate cell-cycle progression participate as targets of NR signaling and coordinate many of these responses. These cyclins and CDKs in turn feed back to modify NR activity. Proteins governing nuclear receptor (estrogen receptor α (ERα), androgen receptor (AR), TR, GR) function can be modified by acetylation. Such proteins include the co-activator (SRC1), co-integrator (p300, p/CAF), HSP-90, histones and HDACs. Phosphorylation, acetylation and ubiquitination occur within transcription factors as a form of intra-transcription factor signaling (signaling cascades within transcription factors; SCITS). The modification of nuclear receptors by acetylation determines gene expression specificity and is a key determining factor of cellular growth in hormoneresponsive cells.

It has been known since the early 1970s that nuclear receptor complexes bind DNA in association with coregulatory proteins. Characterization of these nuclear receptor coregulators has revealed diverse enzymatic activities that temporally and spatially coordinate nuclear receptor activity within the context of local chromatin in response to diverse hormone signals. Chromatin-modifying proteins, which dictate the higher-order chromatin structure in which DNA is packaged, in turn orchestrate orderly recruitment of nuclear receptor complexes. Modifications of histones include acetylation, methylation, phosphorylation, ubiquitylation, sumoylation, ADP ribosylation, deimination, and proline isomerization. At this time, we understand how a subset of these modifications regulates nuclear receptor signaling. However, the effects, particularly of acetylation and demethylation, are profound. The finding that nuclear receptors are directly acetylated and that acetylation in turn directly regulates contact-independent growth has broad therapeutic implications. Studies over the past 7 yr have led to the understanding that nuclear receptor acetylation is a conserved function, regulating diverse nuclear receptor activity. Furthermore, we now know that acetylation of multiple and distinct substrates within nuclear receptor signaling pathways, form an acetylation signaling network from the cell surface to the nucleus. The finding that nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylases, the sirtuins, are capable of deacetylating nuclear receptors provides a new level of complexity in the control of nuclear receptor activity in which local intracellular concentrations of NAD may regulate nuclear receptor physiology.

Endocrine signaling via nuclear receptors (NRs) is known to play an important role in normal physiology as well as in human tumor progression. Hormones regulate gene expression by altering local chromatin structure and, thereby, accessibility of transcriptional co-regulators to DNA. Recently it has been shown that non-histone proteins involved in hormone signaling, such as nuclear receptors and NR co-activators, are regulated by acetylation, resulting in their altered transcriptional activity. NAD-dependent protein deacetylases, the sirtuins (Sir2-related enzymes), directly modify NRs. Because sirtuins have been shown to regulate tumor cellular growth, aging, metabolic signaling and endocrine hormone signaling, they might play a role in cancer progression. This review focuses on the role of acetylation and the sirtuins in nuclear hormone receptor signaling.

The endocrine signaling governing nuclear receptor (NR) function has been known for several decades to play a crucial role in the onset and progression of several tumor types. Notably among these are the estrogen receptor (ER) in breast cancer and androgen receptor (AR) in prostate cancer. Other nuclear receptors may be involved in cancer progression including the peroxisome-proliferator activating receptor gamma (PPARγ), which has been implicated in breast, thyroid, and colon cancers. These NR are phylogenetically conserved modular transcriptional regulators, which like histones, undergo post-translational modification by acetylation, phosphorylation and ubiquitination. Importantly, the transcriptional activity of the receptors is governed by the coactivator p300, the activity of which is thought to be rate-limiting in the activity of these receptors. Histone acetyltransferases (HATs) and histone deacetylases (HDACs), modify histones by adding or removing an acetyl group from the ɛ amino group of lysines within an evolutionarily conserved lysine motif. Histone acetylation results in changes in chromatin structure in response to specific signals. These enzymes can also directly catalyze the NRs themselves, thus modifying signals at the receptor level. The post-translational modification of NR which is regulated by hormones, alters the NR function toward a growth promoting receptor. The deacetylation of NR is mediated by TSA-sensitive and NAD-dependent deacetylases. The regulation of NR by NAD-dependent enzymes provides a direct link between intracellular metabolism and hormone signaling.