Rebecca S Arnold

Emory University, Atlanta, Georgia, United States

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Publications (40)210.37 Total impact

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    ABSTRACT: Aberrant promoter methylation turns off gene expression and is involved in human malignancy. Studies have shown first exon methylation to have tighter association with gene silencing when compared to promoter methylation or gene mutations. However, clinical importance of exonic methylation in renal cell carcinoma (RCC) is unknown. We analyzed RCC tumors for exonic methylation of the von Hippel-Lindau (VHL) gene using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS). Forty-eight institutionally-banked RCC patient tissue samples underwent VHL exon sequencing as well as methylation analysis of both promoter and exon one by either mass spectrometry or conventional bisulfite analysis. 0% and 100% methylated human lymphocytic DNA, non-template dH2O, and two human RCC cell lines (UOK121, UOK171) were used as assay controls. Samples were called hypermethylated if a CpG site exhibited greater than 50% methylation. Forty-three patient samples were read by our exon one assay; nine had methylated VHL exon one sites, with three showing hypermethylation. Exon one methylation assay was robust and reproducible. Samples with exon one hypermethylation did not exhibit exonic mutations. All samples assayed at VHL exon two were hypermethylated. Using MALDI-TOF MS to assay RCC tumors for VHL methylation is robust and reproducible and capable of quantifying methylation status of individual DNA bases. Exon one methylation may be an alternate mechanism of VHL gene silencing in RCC in addition to mutation and promoter methylation. The application of this assay in patient populations may allow enhanced diagnosis or tumor-typing in the future.
    The Journal of urology 04/2014; · 3.75 Impact Factor
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    ABSTRACT: Snail transcription factor can induce epithelial-mesenchymal transition (EMT), associated with decreased cell adhesion-associated molecules like E-cadherin, increased mesenchymal markers like vimentin, leading to increased motility, invasion and metastasis. Muscadine grape skin extract (MSKE) has been shown to inhibit prostate cancer cell growth and induce apoptosis without affecting normal prostate epithelial cells. We investigated novel molecular mechanisms by which Snail promotes EMT in prostate cancer cells via Reactive Oxygen Species (ROS) and whether it can be antagonized by MSKE. ARCaP and LNCaP cells overexpressing Snail were utilized to examine levels of reactive oxygen species (ROS), specifically, superoxide, in vitro using Dihydroethidium (DHE) or HydroCy3 dyes. Mitosox staining was performed to determine whether the source of ROS was mitochondrial in origin. We also investigated the effect of Muscadine grape skin extract (MSKE) on EMT marker expression by western blot analysis. Migration and cell viability using MTS proliferation assay was performed following MSKE treatments. Snail overexpression in ARCaP and LNCaP cells was associated with increased concentration of mitochondrial superoxide, in vitro. Interestingly, MSKE decreased superoxide levels in ARCaP and LNCaP cells. Additionally, MSKE and Superoxide Dismutase (SOD) reverted EMT as evidenced by decreased vimentin levels and re-induction of E-cadherin expression in ARCaP-Snail cells after 3 days, concomitant with reduced cell migration. MSKE also decreased Stat-3 activity in ARCaP-Snail cells. This study shows that superoxide species may play a role in Snail transcription factor-mediated EMT. Therefore, therapeutic targeting of Snail with various antioxidants such as MSKE may prove beneficial in abrogating EMT and ROS-mediated tumor progression in human prostate cancer.
    BMC Complementary and Alternative Medicine 03/2014; 14(1):97. · 1.88 Impact Factor
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    ABSTRACT: Introduction and Objectives. There are over 65,000 new cases of renal cell carcinoma (RCC) each year, yet there is no effective clinical screening test for RCC. A single report claimed no overlap between urine levels of aquaporin-1 (AQP1) in patients with and without RCC (Mayo Clin Proc. 85:413, 2010). Here, we used archived and fresh RCC patient urine to validate this report. Methods. Archived RCC, fresh prenephrectomy RCC, and non-RCC negative control urines were processed for Western blot analysis. Urinary creatinine concentrations were quantified by the Jaffe reaction (Nephron 16:31, 1976). Precipitated protein was dissolved in 1x SDS for a final concentration of 2 μ g/µL creatinine. Results. Negative control and archived RCC patient urine failed to show any AQP1 protein by Western blot analysis. Fresh RCC patient urine is robustly positive for AQP1. There was no signal overlap between fresh RCC and negative control, making differentiation straightforward. Conclusions. Our data confirms that fresh urine of patients with RCC contains easily detectable AQP1 protein. However, archival specimens showed an absence of detectable AQP1 indistinguishable from negative control. These findings suggest that a clinically applicable diagnostic test for AQP1 in fresh urine may be useful for detecting RCC.
    Disease markers 01/2014; 2014:135649. · 2.17 Impact Factor
  • European Urology Supplements 11/2013; 12(6):139. · 3.37 Impact Factor
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    ABSTRACT: Mitochondrial DNA (mtDNA) mutations have been found in many cancers but the physiological derangements caused by such mutations have remained elusive. Prostate cancer is associated with both inherited and somatic mutations in the cytochrome c oxidase (COI) gene. We present a prostate cancer patient-derived rare heteroplasmic mutation of this gene, part of mitochondrial respiratory complex IV. Functional studies indicate that this mutation leads to the simultaneous decrease in cytochrome oxidation, increase in reactive oxygen, and increased reactive nitrogen. These data suggest that mitochondrial DNA mutations resulting in increased reactive oxygen and reactive nitrogen generation may be involved in prostate cancer biology.
    BioMed research international. 01/2013; 2013:239257.
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    Takara A Scott, Rebecca S. Arnold, John A Petros
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    ABSTRACT: Mitochondrial DNA (mtDNA) gene mutations have been described in nearly every adult solid neoplasm including prostate cancer. There are marked racial differences in specific inherited mutations within the cytochrome c oxidase subunit 1 (COI) gene in individuals with prostate cancer (PCa). The purpose of this study was to identify the variation in COI gene sequence in prostate cancer patients and to compare the mutations in African and Caucasian Americans. We sequenced the COI gene in DNA derived from peripheral blood in 482 prostate cancer patients and 189 controls. All bases that differed from the revised Cambridge Reference Sequence (rCRS) were classified as either silent (non-amino acid altering) or missense (amino acid altering) and the compiled alterations were then compared between races and published reports of mutations in this gene in both Caucasian and African-Americans. We found inherited mtDNA COI missense variants in 8.8% of Caucasian prostate cancer patients (vs. 0.0% controls) and 72.8 % of African-American prostate cancer patients (vs. 64.3% controls) A total of 144 COI variants were identified, of which 30 were missense mutations. Of 482 PCa patients, 116 (24.1%) had one or more missense mutations. Further evaluation of this gene and these mutations may allow for the identification of genetically at-risk populations. The high rate of COI mutations in African-Americans may account for some of the racial disparity observed in prostate cancer.
    Scientifica. 01/2012; 2012:701810.
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    ABSTRACT: [This corrects the article on p. e18272 in vol. 6.].
    PLoS ONE 05/2011; 6(5). · 3.53 Impact Factor
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    ABSTRACT: Xenotropic murine leukemia virus-related virus (XMRV) was recently discovered to be the first human gammaretrovirus that is associated with chronic fatigue syndrome and prostate cancer (PC). Although a mechanism for XMRV carcinogenesis is yet to be established, this virus belongs to the family of gammaretroviruses well known for their ability to induce cancer in the infected hosts. Since its original identification XMRV has been detected in several independent investigations; however, at this time significant controversy remains regarding reports of XMRV detection/prevalence in other cohorts and cell type/tissue distribution. The potential risk of human infection, coupled with the lack of knowledge about the basic biology of XMRV, warrants further research, including investigation of adaptive immune responses. To study immunogenicity in vivo, we vaccinated mice with a combination of recombinant vectors expressing codon-optimized sequences of XMRV gag and env genes and virus-like particles (VLP) that had the size and morphology of live infectious XMRV. Immunization elicited Env-specific binding and neutralizing antibodies (NAb) against XMRV in mice. The peak titers for ELISA-binding antibodies and NAb were 1:1024 and 1:464, respectively; however, high ELISA-binding and NAb titers were not sustained and persisted for less than three weeks after immunizations. Vaccine-induced XMRV Env antibody titers were transiently high, but their duration was short. The relatively rapid diminution in antibody levels may in part explain the differing prevalences reported for XMRV in various prostate cancer and chronic fatigue syndrome cohorts. The low level of immunogenicity observed in the present study may be characteristic of a natural XMRV infection in humans.
    PLoS ONE 04/2011; 6(4):e18272. · 3.53 Impact Factor
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    ABSTRACT: Recent studies demonstrated the importance of ADAM9 in prostate cancer relapse upon therapy. In this study, we determined the role of ADAM9 in the therapeutic resistance to radiation and chemotherapy. ADAM9 was either transiently or stably knocked down in C4-2 prostate cancer cells. The sensitivity of ADAM9 knockdown cells toward radiation and chemotherapeutic agents were determined. Additionally, the effects of ADAM9 knockdown on prostate cancer cell morphology, biochemical and functional alterations were accessed. Both transient and stable knockdown of ADAM9 resulted in increased apoptosis and increased sensitivity to radiation. ADAM9 knockdown also increased prostate cancer sensitivity to several chemotherapeutic drugs. ADAM9 knockdown resulted in increased E-cadherin and altered integrin expression and underwent phenotypic epithelial transition. These were reflected by the morphological, biochemical, and functional alterations in the ADAM9 knockdown cells. ADAM9 plays a crucial role in prostate cancer progression and therapeutic resistance in part by altering E-cadherin and integrin expression. ADAM9 is an important target for the consideration of treating prostate cancer patients who developed therapeutic resistance and disease relapse.
    The Prostate 02/2011; 71(3):232-40. · 3.57 Impact Factor
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    ABSTRACT: Reactive oxygen species increases in various diseases including cancer and has been associated with induction of epithelial-mesenchymal transition (EMT), as evidenced by decrease in cell adhesion-associated molecules like E-cadherin, and increase in mesenchymal markers like vimentin. We investigated the molecular mechanisms by which Snail transcription factor, an inducer of EMT, promotes tumor aggressiveness utilizing ARCaP prostate cancer cell line. An EMT model created by Snail overexpression in ARCaP cells was associated with decreased E-cadherin and increased vimentin. Moreover, Snail-expressing cells displayed increased concentration of reactive oxygen species (ROS), specifically, superoxide and hydrogen peroxide, in vitro and in vivo. Real Time PCR profiling demonstrated increased expression of oxidative stress-responsive genes, such as aldehyde oxidase I, in response to Snail. The ROS scavenger, N-acetyl cysteine partially reversed Snail-mediated EMT after 7 days characterized by increased E-cadherin levels and decreased ERK activity, while treatment with the MEK inhibitor, UO126, resulted in a more marked effect by 3 days, characterized by cells returning back to the epithelial morphology and increased E-cadherin. In conclusion, this study shows for the first time that Snail transcription factor can regulate oxidative stress enzymes and increase ROS-mediated EMT regulated in part by ERK activation. Therefore, Snail may be an attractive molecule for therapeutic targeting to prevent tumor progression in human prostate cancer.
    Biochemical and Biophysical Research Communications 01/2011; 404(1):34-9. · 2.28 Impact Factor
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    ABSTRACT: Breast cancer is the most commonly diagnosed cancer in women. Despite recent advances in breast cancer research, a comprehensive set of genetic markers of increased breast cancer risk remain elusive. Recently mitochondrial DNA (mtDNA) mutations have been found in many types of cancer, including breast cancer. To investigate the possible role of mitochondrial genetics in breast cancer predisposition and biology we analyzed the D-loop sequence of cancer patients and assigned mitochondrial haplogroup using RFLP analysis. We detected a significantly greater incidence of mtDNA polymorphisms T239C, A263G and C16207T and a significant lower incidence of A73G, C150T, T16183C, T16189C, C16223T, T16362C in patients with breast cancer compared to database controls. The mitochondrial haplogroup distribution in patients with breast cancer differs from a group of cancer-free controls and the general Polish population in that haplogroup I is over-represented in individuals with cancer. These findings suggest that mitochondrial haplogroup I as well as other polymorphic variants defined by SNPs in the D-loop may be associated with an increased risk of developing breast cancer.
    Oncology Reports 12/2010; 24(6):1521-34. · 2.19 Impact Factor
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    ABSTRACT: The newly identified retrovirus-the xenotropic murine leukemia virus-related virus (XMRV)-has recently been shown to be strongly associated with familial prostate cancer in humans (A. Urisman et al., PLoS Pathog. 2:e25, 2006). While that study showed evidence of XMRV infection exclusively in the prostatic stromal fibroblasts, a recent study found XMRV protein antigens mainly in malignant prostate epithelial cells (R. Schlaberg et al., Proc. Natl. Acad. Sci. U. S. A. 106:16351-16356, 2009). To help elucidate the mechanisms behind XMRV infection, we show that prostatic fibroblast cells express Xpr1, a known receptor of XMRV, but its expression is absent in other cell lines of the prostate (i.e., epithelial and stromal smooth muscle cells). We also show that certain amino acid residues located within the predicted extracellular loop (ECL3 and ECL4) sequences of Xpr1 are required for efficient XMRV entry. Although we found strong evidence to support XMRV infection of prostatic fibroblast cell lines via Xpr1, we learned that XMRV was indeed capable of infecting cells that did not necessarily express Xpr1, such as those of the prostatic epithelial and smooth muscle origins. Further studies suggest that the expression of Xpr1 and certain genotypes of the RNASEL gene, which could restrict XMRV infection, may play important roles in defining XMRV tropisms in certain cell types. Collectively, our data reveal important cellular determinants required for XMRV entry into different human prostate cells in vitro, which may provide important insights into the possible role of XMRV as an etiologic agent in human prostate cancer.
    Journal of Virology 07/2010; 84(13):6288-96. · 4.65 Impact Factor
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    ABSTRACT: To develop a serum-based assay to detect neutralizing antibodies to the xenotropic murine leukemia virus-related virus (XMRV) retrovirus and to use this assay with polymerase chain reaction and fluorescence in situ hybridization to identify patients with prostate cancer previously exposed to XMRV infection and those who carry XMRV viral sequences in their prostate. Patients who had undergone radical prostatectomy were enrolled, and biologic specimens were obtained at surgery. The patients were genotyped for the R462Q RNASEL variant using a TaqMan genotyping assay on DNA from the peripheral blood. A serum assay that detects XMRV neutralizing antibodies was developed and used to determine which patients had serologic evidence of previous infection with XMRV virus. Some of these patients were also tested for the presence of XMRV nucleotide sequences in their prostate using polymerase chain reaction and fluorescence in situ hybridization analysis. At a serum dilution of 1:150, our assay detected 11 (27.5%) of 40 patients with XMRV neutralizing antibodies, including 8 (40%) of 20 with the RNASEL genotype QQ and 3 (15%) of 20 with either the RQ or RR genotype. These results were in complete concordance with 2 other assays (polymerase chain reaction and fluorescence in situ hybridization), which were designed to detect XMRV infection. XMRV infects some patients with prostate cancer. Neutralizing antibodies against XMRV correlated with 2 independent methods of detecting the virus in the prostate. The antibody response suggests that with clinical serologic assay development, it might be possible to screen patients for XMRV infection. The cases presented in the present report provided biologic samples that can be used for the development of a clinically relevant assay.
    Urology 04/2010; 75(4):755-61. · 2.13 Impact Factor
  • The Journal of Urology 04/2010; 183(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2010; 183(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2010; 183(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2010; 183(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2010; 183(4). · 3.75 Impact Factor
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    ABSTRACT: Breast cancer is the most frequently diagnosed female cancer all over the world. Although the molecular genetics of this disease has been the focus of many projects for over 20 years, the number of prognostic markers used in clinics is still unsatisfactory. Mitochondrial DNA mutations have been reported in many breast cancer studies. To investigate the possible role of mitochondrial inherited polymorphisms in breast cancer development we analyzed the sequence of NADH-dehydrogenase genes in cancer samples and their corresponding normal tissues. We detected increased incidence of mtDNA polymorphisms, in particular very rare polymorphisms such as A4727G, G9947A, A10044G, A10283G, T11233C, and C11503T. Our report supports the notion that mtDNA polymorphisms establish a specific genetic background for breast cancer development and that mtDNA analysis may help in selection of cohorts that should undergo intensive screening and early detection programs.
    Oncology Reports 02/2010; 23(2):531-5. · 2.19 Impact Factor
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    ABSTRACT: Mitochondria are subcellular organelles that produce adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS). As suggested over 70 years ago by Otto Warburg and recently confirmed with molecular techniques, alterations in respiratory activity and mitochondrial DNA (mtDNA) appear to be common features of malignant cells. Somatic mtDNA mutations have been reported in many types of cancer cells, but very few reports document the prevalence of inherited mitochondrial DNA polymorphisms in cancer patients compared to healthy control populations. Here we report the abundance of the 10398G polymorphism in a Polish breast cancer population and its frequency in controls. Amongst individuals with breast cancer the G single nucleotide polymorphism (SNP) is present in 23% of affected females compared to 3% of controls. This difference is highly statistically significant (P = 0.0008). It is therefore possible that the 10398G SNP constitutes an inherited predisposition factor for the development of breast cancer.
    Breast Cancer Research and Treatment 04/2009; 121(2):511-8. · 4.47 Impact Factor

Publication Stats

3k Citations
210.37 Total Impact Points

Institutions

  • 1998–2013
    • Emory University
      • • Department of Urology
      • • Department of Pathology and Laboratory Medicine
      • • Department of Biochemistry
      Atlanta, Georgia, United States
  • 2010
    • University of Warsaw
      • Institute of Genetics and Biotechnology
      Warsaw, Masovian Voivodeship, Poland
  • 2006
    • Duke University
      Durham, North Carolina, United States