A novel in vivo approach to assess radial and axial distensibility of large and intermediate pulmonary artery branches

Pulmonary arteries (PAs) distend to accommodate increases in cardiac output. PA distensibility protects the right ventricle (RV) from excessive increases in pressure. Loss of PA distensibility plays a critical role in the fatal progression of pulmonary arterial hypertension (PAH) toward RV failure. However, it is unclear how PA distensibility is distributed across the generations of PA branches, mainly because of the lack of appropriate in vivo methods to measure distensibility of vessels other than the large, conduit PAs. In this study, we propose a novel approach to assess the distensibility of individual PA branches. The metric of PA distensibility we used is the slope of the stretch ratio-pressure relationship. To measure distensibility, we combined invasive measurements of mean PA pressure with angiographic imaging of the PA network of six healthy female dogs. Stacks of 2D images of the PAs, obtained from either contrast enhanced magnetic resonance angiography (CE-MRA) or computed tomography digital subtraction angiography (CT-DSA), were used to reconstruct 3D surface models of the PA network, from the first bifurcation down to the sixth generation of branches. For each branch of the PA, we calculated radial and longitudinal stretch between baseline and a pressurized state obtained via acute embolization of the pulmonary vasculature. Our results indicated that large and intermediate PA branches have a radial distensibility consistently close to 2%/mmHg. Our axial distensibility data, albeit affected by larger variability, suggested that the PAs distal to the first generation may not significantly elongate in vivo, presumably due to spatial constraints. Results from both angiographic techniques were comparable to data from established phase-contrast (PC) magnetic resonance imaging (MRI) and ex vivo mechanical tests, which can only be used in the first branch generation. Our novel method can be used to characterize PA distensibility in PAH patients undergoing clinical right heart catheterization (RHC) in combination with MRI.

MEF2A gene mutations and susceptibility to coronary artery disease in the Chinese population

We investigated mutations and polymorphisms of the coronary artery disease (CAD)-related myocyte enhancer factor 2A (MEF2A) gene in a Chinese population. Polymerase chain reaction-single-strand conformation polymorphism and DNA sequencing were used to detect exon 11 of the MEF2A gene in 210 Hubei patients with CAD and 190 healthy controls. The following mutations were identified: a) a synonymous heterozygous mutation (147191G→T) combined with a 6-base deletion (147123-147128); b) a synonymous heterozygous or homozygous mutation (147191G→T) combined with a 9-base deletion (147123-147131); c) a synonymous mutation (147143G→A); d) a synonymous mutation (147191G→T) combined with an 18-base deletion (147111-147128); and e) a 21-base deletion (147108-147128). Mutations (a) and (b) and a 3-base deletion (147126-147128) with or without the synonymous heterozygous mutation (147191G→T) occurred in more than 1% of controls. However, mutations (c), (d), and (e) were not observed in the control group. The polymorphism in exon 11 of the MEF2A gene was observed in the Chinese population. Six or seven amino acid deletions and synonymous mutations (147143G→A) may be correlated with susceptibility to CAD.

Stimulating β-cell replication and improving islet graft function by AR231453, A GPR119 agonist

OBJECTIVE

G protein-coupled receptor 119 (GPR119) is predominantly expressed in β cells and intestinal L cells. AR231453 is a selective small-molecular GPR119 agonist that enhances glucose-dependent insulin secretion and glucagon-like peptide 1 (GLP-1) release. We investigated whether AR231453 can directly stimulate β-cell replication and improve islet graft function in diabetic mice.

METHODS

A total of 100 syngenic C57BL/6 mouse islets were transplanted under the left kidney of each chemically induced diabetic C57BL/6 mouse. Starting from the day of transplantation, these recipients were given bromodeoxyuridine (BrdU) daily with or without AR231453 at 10 mg/kg/d. Islet graft function was monitored by measuring blood glucose levels. At 4 weeks, left nephrectomy was performed to remove the kidney bearing the islet grafts to determine β-cell replication in the islet grafts. Insulin and BrdU immunofluorescence staining was performed to detect replicated β cells. Insulin(+) and BrdU(+) β cells in islet grafts were counted using a confocal microscope. To determine whether AR231453 increases plasma GLP-1 levels, we collected plasma from AR231453 treated mice at 30 minutes after treatment and measured plasma active GLP-1 by enzyme-linked immunosorbent assay.

RESULTS

Although all recipient mice achieved normoglycemia at 28 days with or without treatment, normoglycemia was achieved in significantly fewer days in AR231453-treated mice. The vehicle-treated mice achieved normoglycemia in 16 ± 6 days, while AR231453-treated mice only required only 8 ± 3 days (P < .01). The percentage of insulin(+) and BrdU(+) β cells in islet grafts was significantly higher in AR231453-treated mice than in vehicle-treated mice. The mean percentage of insulin(+) and BrdU(+) β cells in islet grafts was 21.5% ± 6.9% in AR231453-treated mice and 5.6% ± 3.7% in vehicle-treated mice (P < .01). The plasma active GLP-1 levels were also significantly higher in AR231453-treated mice than in vehicle-treated mice (P < .05).

CONCLUSION

Our data demonstrate that AR231453, a GPR119 agonist, can stimulate β-cell replication and improve islet graft function.

Sevoflurane preconditioning-induced neuroprotection is associated with Akt activation via carboxy-terminal modulator protein inhibition

BACKGROUND

Sevoflurane preconditioning has a neuroprotective effect, but the underlying mechanism is not fully understood. The aim of the present investigation was to evaluate whether sevoflurane-induced cerebral preconditioning involves inhibition of carboxy-terminal modulator protein (CTMP), an endogenous inhibitor of Akt, in a rat model of focal cerebral ischaemia.

METHODS

Male Sprague-Dawley rats were exposed to 2.7% sevoflurane for 45 min. One hour later, rats were subjected to 60 min of focal cerebral ischaemia. The phosphoinositide 3-kinase inhibitors wortmannin and LY294002 were administered 10 min before preconditioning. Rats in the lentiviral transduction group received an intracerebroventricular injection of lentiviral vector Ubi-MCS-CTMP 3 days before ischaemia. Neurological deficits and infarct volumes were evaluated 24 h and 7 days after reperfusion. Phosphorylation of Akt, glycogen synthase kinase-3β (GSK3β), and expression of CTMP were determined at 1, 3, 12, and 24 h after reperfusion. Akt activity was measured at 3 h after reperfusion.

RESULTS

Sevoflurane preconditioning improved neurological score and reduced infarct size at 24 h of reperfusion. Pretreatment with wortmannin or LY294002 attenuated these neuroprotective effects. Expression of CTMP correlated with reduced Akt activity after ischaemia, while sevoflurane preconditioning preserved Akt activity and increased phosphorylation of GSK3β. CTMP over-expression diminished the beneficial effects of sevoflurane preconditioning.

CONCLUSIONS

Activation of Akt signalling via inhibition of CTMP is involved in the mechanism of neuroprotection provided by sevoflurane preconditioning.

Carboxyfullerene neuroprotection postinjury in Parkinsonian nonhuman primates

OBJECTIVE

We evaluated the efficacy of the potent antioxidant C3 to salvage nigrostriatal neuronal function after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) exposure in nonhuman primates. C3 is a first-in-class functionalized water-soluble fullerene that reduces oxygen radical species associated with neurodegeneration in in vitro studies. However, C3 has not been evaluated as a neuroprotective agent in a Parkinson model in vivo.

METHODS

Macaque fascicularis monkeys were used in a double-blind, placebo-controlled study design. MPTP-lesioned primates were given systemic C3 (n = 8) or placebo (n = 7) for 2 months starting 1 week after MPTP. Outcomes included in vivo behavioral measures of motor parkinsonism using a validated nonhuman primate rating scale, kinematic analyses of peak upper extremity velocity, positron emission tomography imaging of 6-[(18) F]fluorodopa (FD; reflects dopa decarboxylase) and [(11) C]dihydrotetrabenazine (DTBZ; reflects vesicular monoamine transporter type 2), ex vivo quantification of striatal dopamine, and stereologic counts of tyrosine hydroxylase-immunostained neurons in substantia nigra.

RESULTS

After 2 months, C3 -treated monkeys had significantly improved parkinsonian motor ratings, greater striatal FD and DTBZ uptake, and higher striatal dopamine levels. None of the C3 -treated animals developed any toxicity.

INTERPRETATION

Systemic treatment with C3 reduced striatal injury and improved motor function despite administration after the MPTP injury process had begun. These data strongly support further development of C3 as a promising therapeutic agent for Parkinson disease.

CD300b regulates the phagocytosis of apoptotic cells via phosphatidylserine recognition

The CD300 receptor family members are a group of molecules that modulate a variety of immune cell processes. We show that mouse CD300b (CLM7/LMIR5), expressed on myeloid cells, recognizes outer membrane-exposed phosphatidylserine (PS) and does not, as previously reported, directly recognize TIM1 or TIM4. CD300b accumulates in phagocytic cups along with F-actin at apoptotic cell contacts, thereby facilitating their engulfment. The CD300b-mediated activation signal is conveyed through CD300b association with the adaptor molecule DAP12, and requires a functional DAP12 ITAM motif. Binding of apoptotic cells promotes the activation of the PI3K-Akt kinase pathway in macrophages, while silencing of CD300b expression diminishes PI3K-Akt kinase activation and impairs efferocytosis. Collectively, our data show that CD300b recognizes PS as a ligand, and regulates the phagocytosis of apoptotic cells via the DAP12 signaling pathway.

Antibody-based imaging of HER-2: moving into the clinic

Human epidermal growth factor receptor-2 (HER-2) mediates a number of important cellular activities, and is up-regulated in a diverse set of cancer cell lines, especially breast cancer. Accordingly, HER-2 has been regarded as a common drug target in cancer therapy. Antibodies can serve as ideal candidates for targeted tumor imaging and drug delivery, due to their inherent affinity and specificity. Advanced by the development of a wide variety of imaging techniques, antibody-based imaging of HER-2 can allow for early detection and localization of tumors, as well as monitoring of drug delivery and tissue's response to drug treatment. In this review article, antibody-based imaging of HER-2 are summarized and discussed, with an emphasis on the involved imaging methods.

Association between resting-state coactivation in the parieto-frontal network and intelligence during late childhood and adolescence

BACKGROUND AND PURPOSE

A number of studies have associated the adult intelligence quotient with the structure and function of the bilateral parieto-frontal networks, whereas the relationship between intelligence quotient and parieto-frontal network function has been found to be relatively weak in early childhood. Because both human intelligence and brain function undergo protracted development into adulthood, the purpose of the present study was to provide a better understanding of the development of the parieto-frontal network-intelligence quotient relationship.

MATERIALS AND METHODS

We performed independent component analysis of resting-state fMRI data of 84 children and 50 adolescents separately and then correlated full-scale intelligence quotient with the spatial maps of the bilateral parieto-frontal networks of each group.

RESULTS

In children, significant positive spatial-map versus intelligence quotient correlations were detected in the right angular gyrus and inferior frontal gyrus in the right parieto-frontal network, and no significant correlation was observed in the left parieto-frontal network. In adolescents, significant positive correlation was detected in the left inferior frontal gyrus in the left parieto-frontal network, and the correlations in the frontal pole in the 2 parieto-frontal networks were only marginally significant.

CONCLUSIONS

The present findings not only support the critical role of the parieto-frontal networks for intelligence but indicate that the relationship between intelligence quotient and the parieto-frontal network in the right hemisphere has been well established in late childhood, and that the relationship in the left hemisphere was also established in adolescence.

Antimycobacterial activity of Pichia pastoris-derived mature bovine neutrophil β-defensins 5

Tuberculosis (TB) is an ongoing threat to global health, and the lack of effective therapies for treating it is also a global problem. Previous studies have shown that human cathelicidin and defensins have effective antimicrobial activity against Mycobacterium spp. To our knowledge, there are no reports on the antimycobacterial effects of bovine neutrophil β-defensins so far. Here, we identified the antimicrobial effect of mature bovine neutrophil β-defensins (mBNBD) 5 against Mycobacterium infection both in vitro and in vivo. The mBNBD5 protein was expressed in Pichia pastoris. To increase the yield of β-defensins, a purification method was employed by adding a 6-His·tag to the C-terminus of the mBNBD5 gene. Our results indicated that recombinant mBNBD5 protein was successfully expressed and purified from Pichia pastoris with intact antimicrobial activity. The recombinant protein exhibited potent bactericidal activity in vitro against M. smegmatis and M. bovis, with a dose-dependent manner and a time-dependent manner. The electron microscope results showed that the bacterial cell wall of M. bovis was disrupted when incubated with mBNBD5 for 72 h. Our data also indicated that the exogenous addition of mBNBD5 could reduce the survival of Mycobacterium spp., especially M. tuberculosis and M. bovis in RAW 264.7 macrophages. These results provide foundations for the development of mBNBD5 as a potential new therapeutic agent for TB treatment.

In vivo measures of nigrostriatal neuronal response to unilateral MPTP treatment

A single unilateral intracarotid infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into non-human primates causes injury to the nigrostriatal pathway including nigral cell bodies, axons and striatal terminal fields. In this model, motor parkinsonism correlates well with the loss of nigral dopaminergic cell bodies but only correlates with in vitro measures of nigrostriatal terminal fields when nigral cell loss does not exceed 50%. The goals of this study are to determine the relationship of motor parkinsonism with the degree of injury to nigrostriatal axons, as reflected by in vitro fiber length density measures, and compare in vivo with in vitro measures of striatal terminal fields. We determined axon integrity by measuring fiber length density with tyrosine hydroxylase (TH) immunohistology and dopamine transporter (DAT) density with DAT immunohistology. We then calculated the terminal arbor size and compared these measures with previously published data of quantified in vivo positron emission tomography (PET) measures of presynaptic dopaminergic neurons, autoradiographic measures of DAT and vesicular monoamine transporter type 2 (VMAT2), striatal dopamine, nigral cell counts, and parkinsonian motor ratings in the same animals. Our data demonstrate that in vivo and in vitro measures of striatal terminal fields correlate with each other regardless of the method of measurement. PET-based in vivo striatal measures accurately reflect in vitro measures of DAT and VMAT2. Terminal arbor size and other terminal field measures correlate with nigral TH immunoreactive (TH-ir) cell counts only when nigral TH-ir cell loss does not exceed 50%. Fiber length density was the only striatal measure that linearly correlated with motor ratings (Spearman: r=-0.81, p<0.001, n=16).

Photochemical behavior of fenpropathrin and λ-cyhalothrin in solution

The photodegradation processes of fenpropathrin and λ-cyhalothrin were studied in hexane, methanol/water (1:1, v/v), and acetone in both ultraviolet light and simulated sunlight. Intermediates in the photodegradation process were identified using gas chromatography/mass spectrometry (GC/MS), and the analysis of intermediates was used to speculate on possible photodegradation pathways. The photodegradation processes of fenpropathrin and λ-cyhalothrin followed pseudo first-order kinetics. The photodegradation rates varied according to the solvent in decreasing order: hexane>methanol/water (1:1, v/v)>acetone. The effects of substances coexisting in the environment on the photodegradation of pyrethroids were also investigated in the research. Acetone, humic acid, and riboflavin increased photodegradation rates while L-ascorbic acid slowed the process. This study provides a theoretical basis for the removal of pyrethroid pollution from the natural environment.

Treatment of polycystic ovarian syndrome with insulin resistance by insulin-sensitizer

OBJECTIVE

The aim of this study was to observe clinical curative effects of combination application of dimethylbiguanide and pioglitazone and single application of pioglitazone in patients with polycystic ovarian syndrome (PCOS) complicated with insulin resistance (IR).

MATERIALS AND METHODS

Forty cases of patients with PCOS complicated with IR were investigated, and 20 cases of infertile women without PCOS were taken as the control group. PCOS group was divided into group A and group B according to body mass index (BMI) to detect glucose and lipids metabolism indicators, C reactive protein (CRP), etc. There were 20 cases in group A (Pioglitazone) and 20 cases in group B (dimethylbiguanide and pioglitazone). After treatment for 12 weeks, changes of the above various indicators were compared.

RESULTS

After treatment, insulin resistance index and serum testosterone (T) of two groups patients with PCOS significantly reduced (p < 0.05). Compared to before treatment, BMI of group B significantly reduced (p < 0.05). For INS at two hours after treatment, group B reduced more significantly (p < 0.05).

CONCLUSION

The combination of dimethylbiguanide and pioglitazone was more effective for the treatment of PCOS complicated with IR than simple pioglitazone; chronic inflammation occurrence was possibly one of reasons for insulin sensitivity reduction of patients with PCOS.

Comparison of 16S rRNA gene PCR and blood culture for diagnosis of neonatal sepsis

Septicemia is a common cause of morbidity and mortality among newborns in the developing world. However, accurate clinical diagnosis of neonatal sepsis is often difficult because symptoms and signs are often nonspecific. Blood culture has been the gold standard for confirmation of the diagnosis. However, the sensitivity is low and results are usually not promptly obtained. Therefore, the diagnosis of sepsis is often based on clinical signs in association with laboratory tests such as platelets count, immature/total neutrophils ratio (I/T), and a rise in C-reactive protein (CRP). Polymerase chain reaction (PCR) methods for the detection of neonatal sepsis represent new diagnostic tools for the early identification of pathogens.

METHODS

During a 4-month prospective study, 16S rRNA PCR was compared with conventional blood culture for the diagnosis of neonatal bacterial sepsis. In addition, the relationship between known risk factors, clinical signs, laboratory parameters, and the diagnosis of sepsis was considered.

RESULTS

Sepsis was suspected in 706 infants from the intensive neonatal care unit. They all were included in the study. The number of positive cultures and positive PCR results were 95 (13.5%) and 123 (17.4%), respectively. Compared with blood culture, the diagnosis of bacterial sepsis by PCR revealed a 100.0% sensitivity, 95.4% specificity, 77.2% positive predictive value, and 100.0% negative predictive value. In this study, Apgar scores at 5 min, weight, icterus, irritability, feeding difficulties, gestational age (GA), premature rupture of membrane (PRM), platelets count, I/T, and a marked rise in CRP were important in establishing the diagnosis of sepsis in the newborn. In addition, weight, GA, PRM, irritability, duration of antibiotic usage, mortality rate, and number of purulent meningitis cases were significantly different between early-onset sepsis and late-onset sepsis.

CONCLUSION

16S rRNA PCR increased the sensitivity in detecting bacterial DNA in newborns with signs of sepsis, allowed a rapid detection of the pathogens, and led to shorter antibiotic courses. However, uncertainty about the bacterial cause of sepsis was not reduced by this method. 16S rRNA PCR needs to be further developed and improved. Blood culture is currently irreplaceable, since pure isolates are essential for antimicrobial drug susceptibility testing.

Abstract P5-08-02: New target in the resistant mechanism to trastuzumab

Her2 positive (Her2+) breast cancer (BC) accounts for 18-20% of all breast cancer subtypes and is associated with high risk of death. Trastuzumab, the first Food and Drug Administration-approved targeted therapy for BC, represents a key milestone in the personalized treatment of Her2+ metastatic disease (Her2+ MBC). However, the median duration of response is less than a year, due to either primary or acquired resistance to the therapy. In addition, there is currently no conclusive biomarker for the response of patients to trastuzumab. Therefore, understanding the development of resistance to trastuzumab is of our interest. Recent studies have proposed various potential mechanisms leading to the resistance, including p27 rapid degradation. Previously, our study and other research demonstrated that Jab1 degrades p27 in breast cancer. These findings suggest that Jab1 over-expression contributes to trastuzumab resistance by facilitating p27 degradation.

Jab1/CSN5 (c-Jun activation domain-binding protein 1) is over-expressed in 50% of primary and 90% of metastatic breast cancers, while its expression is low or absent in normal adult breast tissues. We previously identified that high expression of Jab1 is associated with shorter progression-free survival in breast cancer patients. In this study, our preliminary data showed that the knockdown of Jab1 sensitizes the breast cancer cells to trastuzumab treatment in a dose-dependent manner. Mechanistically, we found that Jab1 over-expression is significantly correlated with the activation of Akt pathway in Her2+ breast cancer cells and xenograft model. Interestingly, activated Akt, due to PTEN loss or PI3K activating mutation has been widely implicated in the potential mechanism to trastuzumab resistance. Therefore, our results suggest that targeting Jab1 overcomes the resistance to trastuzumab via interfering with PI3K/Akt pathway.

In general, our study identifies Jab1 as a novel contributor to trastuzumab resistance and elucidates its potential mechanisms of actions. The successful completion of the study can potentially be translated to the clinic for the benefit of patients refractory to the therapy. Also our study suggests Jab1 expression level can be used as a predictive marker for trastuzumab treatment.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-02.

Abstract P2-06-02: Pparg deacetylation by SIRT1 determines breast tumor lipid synthesis and growth

Peroxisome proliferator-activated receptorg (Pparγ) is a member of the nuclear receptor (NR) superfamily, which regulates diverse biological functions including lipogenesis and differentiation, anti-inflammation, insulin sensitivity, cellular proliferation, and autophagy. Independent lines of evidence support a role for Pparγ as either a collaborative oncogene or as a tumor suppressor. Heterozygous mutations of Pparγ have been detected in 4/55 patients with colon cancer and a chromosomal translocation between PAX8 and Pparγ in follicular thyroid cancer appeared to serve as a dominant inhibitor of endogenous Pparγ expression. Pparγ agonists reduced tumorigenesis in several in vivo models. In contrast, several studies suggest Pparγ may enhance tumor growth. Pparγ ligands increased polyp numbers in the Apc mouse model of familial adenomatosis. Pparγ and its ligands inhibit breast tumor growth; however, constitutively active Pparγ collaborated in mammary oncogenesis with polyoma middle T antigen or oncogenic ErbB2.

Pparγ activation involves post-translational modifications including phosphorylation and sumoylation upon growth factor or ligand stimulus. Mutation of the Pparγ1 sumoylation site at K77 and K365 demonstrated that K77 may either reduce Pparγ-dependent gene induction and enhance repression or reduce repression, depending upon the synthetic reporter gene used. Lysine residues of nuclear receptors also serve as substrates for acetylation and Pparγ binds co-activators and co-repressors with intrinsic or associated histone acetylase or deacetylase activity including NCoR, SMRT, SIRT1, and p300. Initially characterized for the ERα, AR and, subsequently, the orphan nuclear receptor steroidogenic factor 1 (SF-1), acetylation occurs at a conserved lysine motif shared amongst evolutionarily related nuclear receptors. Several nuclear receptors and co-integrators involved in lipid metabolism are regulated by acetylation including p300, PGC1α, FXR, LXR and RAR. Both TSA- and NAD-sensitive HDACs (e.g. SIRT1) regulate Pparγ function and SIRT1 inhibits Pparγ-dependent adipocyte differentiation. Whether Pparγ is acetylated in cancer cells and how Pparγ exerts it's crucial, though controversial, function in tumorigenesis have not been established.

Pparγ induces gene transcription through binding specific NR half-sites and through non-canonical binding sequences (such as CREB/AP-1 sites). Transcriptional repression involves Pparγ sumoylation at lysine 77 (K77). Herein, Pparγ was shown to be acetylated at nine distinct lysine residues. SIRT1 bound and deacetylated Pparγ at K154/155. ChIP-Seq analysis for genome-wide DNA binding demonstrated the acetylation site was required for binding NR half-sites, but was not required for non-canonical site binding. Breast tumor growth, de novo lipid synthesis, induction of autophagy and evasion of apoptosis was promoted by K154/155 and inhibited by K77 in vivo. Pparγ acetylation induced a gene signature that was increased in breast cancer, associated with a reduction in SIRT1 abundance and poor outcome. The Pparγ acetylation site determines binding to autophagy and apoptosis signaling to regulate breast tumor lipid metabolism and growth.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-06-02.

Abstract P3-02-03: The phosphatase function of the eyes absent (EYA) homolog is required for the induction of breast cancer cellular proliferation via cyclin D1

The Drosophila Eyes Absent Homologue 1 (EYA1) is a component of the retinal determination gene network (RDGN) and serves as an H2AX phosphatase. The cell fate determination gene network includes the dachshund (dac), twin-of-eyeless (toy), eye absent (eya), teashirt (tsh) and sine oculis (So). In Drosophila, mutations of the RDGN leads to failure of eye formation, whereas, forced expression induces ectopic eye formation. EYA functions as a transcriptional co-activator being recruited in the context of local chromatin, but lacking intrinsic DNA binding activity. EYA family members EYA 1-4 are defined by a 275 amino acid carboxyl-terminal motif that is conserved between species, referred to as the EYA domain (ED). The human homologs EYA 1-4 are highly conserved in their EYA domain and amino termini, with the exception of a small tyrosine rich residue region named EYA domain II.

Altered expression or functional activity of the RDGN has been documented in a variety of malignancies. DACH1 expression is reduced in breast, prostate, endometrial and brain cancer. EYA2 is up regulated in ovarian cancer, promoting tumor growth. EYA1 and EYA2 enhanced survival in response to DNA damage producing agents in HEK293 cells. Eya2 was required for Six1/TGFb signals that govern a prometastatic phenotype and epithelial mesenchymal transition (EMT). Although EYA proteins are expressed in human breast cancer, the relationship to molecular genetic subtype, prognosis and the molecular mechanisms governing contact-independent growth are not known.

The cyclin D1 gene encodes the regulatory subunits of a holoenzyme that phosphorylates and inactivates the pRb protein. Herein, comparison with normal breast demonstrated EYA1 is overexpressed with cyclin D1 in luminal B breast cancer subtype. EYA1 enhanced breast tumor growth in mice in vivo requiring the phosphatase domain. EYA1 enhanced cellular proliferation, inhibited apoptosis, and induced contact-independent growth and cyclin D1 abundance. The induction of cellular proliferation and cyclin D1 abundance, but not apoptosis, was dependent upon the EYA1 phosphatase domain. The EYA1-mediated transcriptional induction of cyclin D1 occurred via the AP-1 binding site at -953 and required the EYA1 phosphatase function. The AP-1 mutation did not affect SIX1-dependent activation of cyclin D1. EYA1 was recruited in the context of local chromatin to the cyclin D1 AP-1 site. The EYA1 phosphatase function determined the recruitment of CBP, RNA polymerase II and acetylation of H3K9 at the cyclin D1 gene AP-1 site regulatory region in the context of local chromatin. The EYA1 phosphatase regulates cell cycle control via transcriptional complex formation at the cyclin D1 promoter.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-02-03.