Abstract P5-10-08: Hyperactive MAPK signaling alters expression of miR-221/222 and miR-30 families, which impacts multiple pathways and contributes to breast cancer aggressiveness and progression

We have previously identified a patient-derived microRNA signature indicative of hyperactive MAPK (hMAPK) signaling in breast cancer. This signature associates with reduced estrogen receptor (ER) expression, and altered protein expression of a multitude of genes associated with breast cancer aggressiveness and progression. Additionally, this signature predicts poor clinical outcome with reduced disease free survival and overall survival in all comers, and especially among patients with ER+ tumors. Many of the proteins whose expression is altered in tumors with this hMAPK-miRNA signature are predicted or validated targets of miRNAs within the signature. We hypothesize that alterations in expression of hMAPK-miRNAs directly affect post-transcriptional regulation of a subset of these proteins. Using a hMAPK cell line model of breast cancer generated from an MCF-7 background, we investigated the involvement of hMAPK-miRNAs in post-transcriptional regulation and resulting dynamics of expression of several proteins identified as being differentially expressed between hMAPK-tumors and not-hMAPK-tumors.

Here we have investigated the hMAPK regulation of one miRNA family that is upregulated and one miRNA family that is downregulated in the hMAPK signature. Each of these families has key validated targets important in breast cancer, and many other putative gene targets. The miR-221/222 family is upregulated in the hMAPK-miRNA signature, and is a negative regulator of ER and the cell cycle regulator p27. In our breast cancer cell line model, we have previously demonstrated that miR-221/222 are upregulated and ER and p27 are downregulated in hMAPK cells vs control transfected MCF-7 cells. We now show that inhibiting MAPK signaling with pharmacological inhibitors reduces the expression of miR-221/222, and results in enhanced expression of ER and p27; we confirm that this regulation occurs at the post-transcriptional level using a dual-luciferase reporter construct containing the ER 3′ UTR. Additionally, stimulation of MAPK signaling dynamically increases the expression of miR-221/222 and decreases ER and p27 expression. These results indicate that hMAPK signaling directly alters expression of ER and p27 by altering miRNA expression. Members of the miR-30 family are downregulated in the hMAPK-miRNA signature, and several proteins that upregulated in hMAPK-miRNA tumors vs not-hMAPK-miRNA tumors, including SNAIL, NOTCH1, and FOXO3, are all targets of the miR-30 family. Using our cell line model, we have shown that members of the miR-30 family are downregulated by hMAPK signaling, that SNAIL is upregulated, and that abrogation of hMAPK signaling reverses these changes.

It is known that SNAIL and ER exhibit inverse expression in breast cancer cells, and these data suggest that this is due to hMAPK mediated miRNA activity. Thus, hMAPK signaling may contribute to increased EMT, ER-negativity, and poor clinical outcome observed in breast tumors with this hMAPK-miRNA signature via the direct action of these hMAPK-regulated miRNAs. These results suggest novel mechanisms by which hMAPK signaling may contribute to breast cancer disease aggressiveness and progression.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-10-08.

Indigenous peoples of North America: environmental exposures and reproductive justice

BACKGROUND

Indigenous American communities face disproportionate health burdens and environmental health risks compared with the average North American population. These health impacts are issues of both environmental and reproductive justice.

OBJECTIVES

In this commentary, we review five indigenous communities in various stages of environmental health research and discuss the intersection of environmental health and reproductive justice issues in these communities as well as the limitations of legal recourse.

DISCUSSION

The health disparities impacting life expectancy and reproductive capabilities in indigenous communities are due to a combination of social, economic, and environmental factors. The system of federal environmental and Indian law is insufficient to protect indigenous communities from environmental contamination. Many communities are interested in developing appropriate research partnerships in order to discern the full impact of environmental contamination and prevent further damage.

CONCLUSIONS

Continued research involving collaborative partnerships among scientific researchers, community members, and health care providers is needed to determine the impacts of this contamination and to develop approaches for remediation and policy interventions.

A self-regulating cell culture analog device to mimic animal and human toxicological responses

The overall goal of this project is the development of a new methodology for translating advances in molecular level understanding of toxicological responses into a predictive tool for dose response in whole animals and humans exposed to single compounds or mixtures of compounds. The methodology incorporates a mechanistic cellular level model into a PBPK (physiologically based pharmacokinetic) model which simultaneously guides the development of an in vitro cell culture analog (CCA) to the PBPK. Where the PBPK specifies an organ, (e.g., liver) the in vitro or CCA system contains a compartment with the appropriate cell or cell population (e.g., hepatocytes for the liver). The CCA has significant advantages over other in vitro systems and PBPK systems used independently for evaluating metabolic responses to drugs or potentially toxic chemicals where the exchange of metabolites between organs is likely to be important. The CCA system is superior to a PBPK because an a priori description of complete metabolism is not required and secondary, unexpected interactions can be detected. The CCA system, unlike other in vitro systems, gives a dynamic response that realistically simulates in vivo interactions between organs. Furthermore, the CCA allows dosing on the same basis as animal tests (e.g., milligrams per kilogram of body mass equivalent). Because the construction of a CCA is guided by a PBPK, this approach allows extrapolation to low doses and across species, including extrapolation to humans. We have constructed a prototype system and have conducted proof-of-concept experiments using naphthalene as a test chemical. These experiments clearly demonstrate the ability to generate a reactive metabolite in one compartment and detect its effects (on LDH release and glutathione depletion) in a second compartment. However, this prototype device would be expensive to replicate and requires nearly constant supervision from a trained investigator. For this concept to replace animals an inexpensive, self-regulating device is needed. An initial design to accomplish this goal is described as well as the corresponding model using naphthalene as a test compound. (c) 1996 John Wiley & Sons, Inc.

National Bone Health Alliance Bone Turnover Marker Project: current practices and the need for US harmonization, standardization, and common reference ranges

This position paper reviews how the National Bone Health Alliance (NBHA) will execute a project to help assure health professionals of the clinical utility of bone turnover markers; the current clinical approaches concerning osteoporosis and the status and use of bone turnover markers in the USA; the rationale for focusing this effort around two specific bone turnover markers; the need to standardize bone marker sample collection procedures, reference ranges, and bone turnover marker assays in clinical laboratories; and the importance of harmonization for future research of bone turnover markers.

INTRODUCTION

Osteoporosis is a major global health problem, with the prevalence and incidence of osteoporosis for at-risk populations estimated to be 44 million Americans. The potential of bone markers as an additional tool for health care professionals to improve patient outcomes and impact morbidity and mortality is crucial in providing better health care and addressing rising health care costs. This need to advance the field of bone turnover markers has been recognized by a number of organizations, including the International Osteoporosis Foundation (IOF), National Osteoporosis Foundation, International Federation of Clinical Chemistry, and Laboratory Medicine (IFCC), and the NBHA.

METHODS

This position paper elucidates how this project will standardize bone turnover marker sample collection procedures in the USA, establish a USA reference range for one bone formation (serum procollagen type I N propeptide, s-PINP) and one bone resorption (serum C-terminal telopeptide of type I collagen, s-CTX) marker, and standardize bone turnover marker assays used in clinical laboratories. This effort will allow clinicians from the USA to have confidence in their use of bone turnover markers to help monitor osteoporosis treatment and assess future fracture risk. This project builds on the recommendations of the IOF/IFCC Bone Marker Standards Working Group by developing USA reference standards for s-PINP and s-CTX, the markers identified as most promising for use as reference markers.

RESULTS

The goals of this project will be realized through the NBHA and will include its governmental, academic, for-profit, and non-profit sector stakeholders as well as major academic and commercial laboratories. Upon completion, a parallel effort will be pursued to make bone turnover marker measurements reliable and accepted by all health care professionals for facilitating treatment decisions and ultimately be reimbursed by all health insurance payers.

CONCLUSIONS

Successful completion of this project will help assure health professionals from the USA of the clinical utility of bone turnover markers and ties in with the parallel effort of the IOF/IFCC to develop worldwide bone turnover reference ranges.

Endomyocardial fibrosis: the first report from Malawi

Endomyocardial fibrosis (EMF) is a restrictive cardiomyopathy of unknown aetiology previously unreported in Malawi. Six Malawian children (three males) aged between 12 and 16 years who presented with EMF in 2009/10 are described. Five were from the Southern Highlands.

TRIM32 regulates skeletal muscle stem cell differentiation and is necessary for normal adult muscle regeneration

Limb girdle muscular dystrophy type 2H (LGMD2H) is an inherited autosomal recessive disease of skeletal muscle caused by a mutation in the TRIM32 gene. Currently its pathogenesis is entirely unclear. Typically the regeneration process of adult skeletal muscle during growth or following injury is controlled by a tissue specific stem cell population termed satellite cells. Given that TRIM32 regulates the fate of mammalian neural progenitor cells through controlling their differentiation, we asked whether TRIM32 could also be essential for the regulation of myogenic stem cells. Here we demonstrate for the first time that TRIM32 is expressed in the skeletal muscle stem cell lineage of adult mice, and that in the absence of TRIM32, myogenic differentiation is disrupted. Moreover, we show that the ubiquitin ligase TRIM32 controls this process through the regulation of c-Myc, a similar mechanism to that previously observed in neural progenitors. Importantly we show that loss of TRIM32 function induces a LGMD2H-like phenotype and strongly affects muscle regeneration in vivo. Our studies implicate that the loss of TRIM32 results in dysfunctional muscle stem cells which could contribute to the development of LGMD2H.

P3-03-07: A Novel Approach Integrating microRNA and mRNA Signatures of HMAPK Signaling Is Highly Predictive of ER- Status and Outcome in Breast Cancer – Role of HMAPK microRNAs in Repression of ER and p27

Deregulation of the MAPK signaling pathway in breast cancer is known to facilitate the down-regulation of the estrogen receptor and to contribute to the aggressive nature of ER negative and triple negative breast cancers. We have identified a microRNA signature indicative of hyperactive MAPK (hMAPK) signaling, which complements a previously established hyperactive MAPK gene expression signature. We have shown that hMAPK signaling also alters the regulatory activity of many microRNAs, including particular microRNAs with established roles in the biology of breast cancer, miR-221/222 and miR-22. Expression correlation with both the hMAPK microRNA signature and hMAPK mRNA signature is significantly associated with ER-negative status, increased tumor grade, high proliferation rate, and, importantly, poor disease specific survival among breast cancer patients, regardless of ER status. The hMAPK microRNA signature contains 127 microRNAs, 47 up-regulated and 70 down-regulated. Of note, hMAPK up-regulated microRNAs include miR-221/222 and 22, both of which have been demonstrated to target ER while miR-221/222 targets the cell cycle regulatory protein p27. Down-regulated microRNAs include miR-375, which positively regulates ER expression by down-regulating expression of an ER repressor. miR-221/222 and miR-22 exhibit both enhanced expression and enhanced regulatory activity in the context of hMAPK signaling, indicating an important role for these microRNAs in the biology of hMAPK signaling in breast cancer. In addition to these microRNAs, an unbiased approach of determining MAPK regulated microRNAs targeting the 3’ UTRs of both ER and p27 will identify novel microRNAs involved in the MAPK regulated repression of ER and p27. These data not only suggest a regulatory role for microRNAs whose expression and biological activity are altered under conditions of hyperactivation of MAPK signaling in establishing and maintaining ER negativity and tumor aggression, but also indicate that hMAPK signaling may represent a novel aggressive tumor biology that is indicative of poor disease outcome in breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-03-07.

Prenatal diagnosis, management and outcome of fetal dysrhythmia: a tertiary fetal medicine centre experience over an eight-year period

OBJECTIVE

To review the prenatal diagnosis, management and outcome of fetal dysrhythmia.

SUBJECTS AND METHODS

Prenatal diagnosis, management and outcomes of fetuses with dysrhythmia were reviewed retrospectively (01/01/1997 to 31/12/2004).

RESULTS

Over an 8-year period, 318 pregnant mothers were referred for assessment of suspected fetal dysrhythmias. Median gestation was 30 weeks (range 19-41). Fetal dysrhythmia was identified in 182 (57%) and classified as: (i) 126 atrial extrasystoles; (ii) 26 tachyarrhythmia, and (iii) 30 bradyarrhythmia. Of the fetuses with tachyarrhythmia, 23 had supraventricular tachycardia (SVT), 2 atrial flutter and 1 sinus tachycardia. One death associated with severe hydrops occurred in the tachyarrhythmia group. 19 cases of SVT were successfully treated in utero. Both cases of atrial flutter required direct current cardioversion in the neonatal period. In the bradyarrhythmia group, there were 15 isolated cases and 10 cases associated with congenital heart disease, with 73 and 20% survival, respectively.

CONCLUSIONS

Benign atrial extrasystoles are the commonest cause for referral and assessment of fetal dysrhythmia. The overall prognosis for SVT is good with the majority responding to transplacental therapy. In cases with congenital atrioventricular block, the outcome was less favourable, especially when the atrioventricular block was associated with congenital heart disease.

Schottky Contact Behaviour as a Function of Metal and ZnO Surface Polarity

Hall effect, photoluminescence (PL) and Schottky diode measurements were made on the Zn-polar , O-polar and m-plane faces of hydrothermally grown, bulk ZnO. Several polarity related differences were observed in the PL spectra. The most noticeable was increased emission from free excitons and from a triplet of emissions at 3.3725 - 3.3750 eV on the Zn-polar face. Polarity effects were also observed in the properties of highly rectifying, planar, silver oxide diodes fabricated by RF sputtering using an Ag target and an Ar/O2 plasma. The most significant of these was a consistent 130 meV larger barrier height for silver oxide diodes on the Zn-polar face compared to the O-polar face. These polarity effects are thought to result from the internal compensation of bound spontaneous polarization charges at the Zn-polar and O-polar faces. In addition, Au and Ag Schottky diodes with image-force-controlled ideality factors were achieved on the Zn-polar face of bulk ZnO without any special surface treatments.

Plasma pharmacokinetics of two consecutive doses of ferumoxytol in healthy subjects

Intravenous (IV) iron is used to treat iron-deficiency anemia in patients with chronic kidney disease (CKD). Ferumoxytol is a novel iron formulation administered rapidly as two IV boluses of 510 mg each. In this placebo-controlled, double-blind, parallel-group study, 58 healthy volunteers received ferumoxytol in two 510 mg doses administered 24 h apart. Population pharmacokinetics (PK) analysis was conducted, and a two-compartment open model with zero-order input and Michaelis-Menten elimination was found to best describe the data. The population mean estimates for volume of distribution of the central compartment (V(1)), maximal elimination rate (V(max)), and ferumoxytol concentration at which rate of metabolism would be one-half of V(max) (K(m)) were 2.71 l, 14.3 mg/h, and 77.5 mg/l, respectively. When the effect of body weight on V(1) was added in the analysis, interindividual variability was found to be reduced. A noncompartmental analysis of two simulated 510-mg ferumoxytol doses was also performed to provide clinically interpretable data on half life and exposure. Ferumoxytol given as two consecutive 510-mg doses was well tolerated.

Screening actinomycetes for extracellular peroxidase activity

A diverse collection of actinomycete strains were screened for production of extracellular peroxidase activity by adapting a chemiluminescence analysis system developed for horseradish peroxidase-based enzyme-linked immunosorbent assay. Extracellular peroxidase activity was found to be common but quantitatively variable, and this rapid and sensitive screening system permitted identification of a small group of high-producing strains. A range of spectrophotometric assays were compared for the measurement of peroxidase activity in concentrated culture supernatants of two selected thermophilic streptomycetes. Of these, the peroxide-dependent oxidation of 2,4-dichlorophenol was identified as the most robust and reproducible assay for quantitative studies.

Identification of ER Negative Tumors in Which MAPK Inhibition Restores Both ER Expression and Anti-Estrogen Responses

Background: Approximately 35% of breast cancer lacks expression of the estrogen receptor α (ERα). ERα negative breast cancer carries a poorer prognosis compared to ERα+ breast cancer, but more importantly, it precludes the use of less toxic anti-estrogen therapies. Our previous data suggest that many ERα- breast tumors have the potential to express ERα, but ERα expression is repressed by hyperactive MAPK as a result of altered growth factor signalling pathways. We have shown that hyperactive MAPK results in down-regulation of ERα and treatment that inhibits MAPK activity results in re-expression of ERα protein and restoration of anti-estrogen sensitivity in both in vitro cell line and ex vivo primary culture model systems.Results: Using a panel of 9 primary cultures established from ERα- breast tumors, we have examined the incidence of MAPK inhibition mediated restoration of ERα expression. Of the 9 primary cultures examined to date, 5 are from triple negative tumors and 4 are from ERα-/PR-/H2N+ tumors. Of the 5 triple negative cultures analyzed, 3 re-express ERα upon MAPK inhibition, while 2 do not, and all 4 ERα-/H2N+ cultures re-express ERα. Although each of these primary cultures exhibited wide variation in the level of hyperactive MAPK, in those that re-expressed ERα, it was successful inhibition of MAPK activity that led to the re-expression of ERα. To establish determinants of the subset of ERα- breast tumors in which MAPK inhibition will restore ERα expression and more importantly, those in which MAPK inhibition restores both ERα expression and anti-estrogen responses, we have performed both proteomic and genomic profiling of these 9 primary cultures in the absence and presence of MAPK inhibition. Key differences between those primary cultures that re-express ERα vs those that do not, and interestingly, between triple negative primary cultures that re-express ERα vs those that express Her2 and re-express ERα upon MAPK inhibition have been identified. The role of these in determining restoration of anti-estrogen responses as well are being established.Discussion: Our overall goal is to understand the mechanisms underlying ERα- breast cancer and to develop novel therapies for ERα- breast cancer based on the re-expression of ERα and restoration of anti-estrogen responses. Having shown that hyperactive MAPK can repress ERα expression, and more importantly that inhibition of MAPK can restore functional ERα expression, we now need to establish the subsets of ERα- breast cancer in which each of this mechanism is responsible for the lack of ERα expression. This knowledge will allow us to determine which ERα- breast cancer patients may benefit from the combined inhibition of MAPK and ERα. The ability to use drugs with low toxicity to re-express ERα in ERα- tumors and thus render them sensitive to anti-estrogens would be a major leap forward in the treatment of ERα- breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 404.