Doris M Benbrook

Oklahoma City University, Oklahoma City, Oklahoma, United States

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Publications (99)425.46 Total impact

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    Bulent Ozpolat · Doris M Benbrook ·
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    ABSTRACT: Autophagy is a highly regulated catabolic process involving lysosomal degradation of intracellular components, damaged organelles, misfolded proteins, and toxic aggregates, reducing oxidative stress and protecting cells from damage. The process is also induced in response to various conditions, including nutrient deprivation, metabolic stress, hypoxia, anticancer therapeutics, and radiation therapy to adapt cellular conditions for survival. Autophagy can function as a tumor suppressor mechanism in normal cells and dysregulation of this process (ie, monoallelic Beclin-1 deletion) may lead to malignant transformation and carcinogenesis. In tumors, autophagy is thought to promote tumor growth and progression by helping cells to adapt and survive in metabolically-challenged and harsh tumor microenvironments (ie, hypoxia and acidity). Recent in vitro and in vivo studies in preclinical models suggested that modulation of autophagy can be used as a therapeutic modality to enhance the efficacy of conventional therapies, including chemo and radiation therapy. Currently, more than 30 clinical trials are investigating the effects of autophagy inhibition in combination with cytotoxic chemotherapies and targeted agents in various cancers. In this review, we will discuss the role, molecular mechanism, and regulation of autophagy, while targeting this process as a novel therapeutic modality, in various cancers.
    Cancer Management and Research 09/2015; 7:291-9. DOI:10.2147/CMAR.S34859
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    ABSTRACT: Flexible Heteroarotinoids (Flex-Hets) are a class of substituted di-aryl compounds that exhibit potent anti-cancer activity without toxicity. They were derived from the more conformationally restricted, 2-atom linker Hets by substitution of the 2-atom linker with a 3-atom urea or thiourea linker, which conferred more potent inhibitory activity against cancer cell lines. The objectives of this structure activity relationship (SAR) study were to determine if a 4-atom acrylamide linker and various substitutions on the terminal aryl ring altered the anti-cancer activity of these second generation Flex-Het compounds compared to the parent Flex-Het compound, SHetA2, which has a thiourea linker and a nitro substituent. Biological activity was measured using a cytotoxicity assay of the human A2780 ovarian cancer cell line treated with a range of compound concentrations. Nitrogen-based substitutions on the terminal aryl group caused similar, but slightly reduced efficacies and potencies. Exceptions were systems that had a nitro group at the para position, the potencies of which were better than that of SHetA2 with efficacies that were only slightly reduced compared to SHetA2. Similarly, the potency of the system with a para dimethylamino group was greater than that of SHetA2. However, a 30% reduction in efficacy compared to SHetA2 was noted. While specific members with the 4-atom acrylamide linker did exhibit excellent potency, the efficacy was slightly below that of SHetA2. Thus, a gradient of activities was observed as the substituent on the aryl ring was altered. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    European Journal of Medicinal Chemistry 04/2015; 96:209-217. DOI:10.1016/j.ejmech.2015.03.070 · 3.45 Impact Factor

  • Brachytherapy 02/2015; 14(1). DOI:10.1016/j.brachy.2014.08.025 · 2.76 Impact Factor
  • Doris Mangiaracina Benbrook ·

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    ABSTRACT: Purpose: Brivanib, an oral, multi-targeted tyrosine kinase inhibitor with activity against vascular endothelial growth factor (VEGF) and fibroblast growth factor receptor (FGFR) was investigated as a single agent in a phase II trial to assess the activity and tolerability in recurrent or persistent endometrial cancer (EMC). Patients and methods: Eligible patients had persistent or recurrent EMC after receiving one to two prior cytotoxic regimens, measurable disease, and performance status of ≤2. Treatment consisted of brivanib 800 mg orally every day until disease progression or prohibitive toxicity. Primary endpoints were progression-free survival (PFS) at six months and objective tumor response. Expression of multiple angiogenic proteins and FGFR2 mutation status was assessed. Results: Forty-five patients were enrolled. Forty-three patients were eligible and evaluable. Median age was 64 years. Twenty-four patients (55.8%) received prior radiation. Median number of cycles was two (range 1-24). No GI perforations but one rectal fistula were seen. Nine patients had grade 3 hypertension, with one experiencing grade 4 confusion. Eight patients (18.6%; 90% CI 9.6%-31.7%) had responses (one CR and seven PRs), and 13 patients (30.2%; 90% CI 18.9%-43.9%) were PFS at six months. Median PFS and overall survival (OS) were 3.3 and 10.7 months, respectively. When modeled jointly, VEGF and angiopoietin-2 expression may diametrically predict PFS. Estrogen receptor-α (ER) expression was positively correlated with OS. Conclusion: Brivanib is reasonably well tolerated and worthy of further investigation based on PFS at six months in recurrent or persistent EMC.
    Gynecologic Oncology 07/2014; 135(1). DOI:10.1016/j.ygyno.2014.07.083 · 3.77 Impact Factor
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    ABSTRACT: The discovery of retinoic acid receptors arose from research into how vitamins are essential for life. Early studies indicated that Vitamin A was metabolized into an active factor, retinoic acid (RA), which regulates RNA and protein expression in cells. Each step forward in our understanding of retinoic acid in human health was accomplished by the development and application of new technologies. Development cDNA cloning techniques and discovery of nuclear receptors for steroid hormones provided the basis for identification of two classes of retinoic acid receptors, RARs and RXRs, each of which has three isoforms, α, β and ɣ. DNA manipulation and crystallographic studies revealed that the receptors contain discrete functional domains responsible for binding to DNA, ligands and cofactors. Ligand binding was shown to induce conformational changes in the receptors that cause release of corepressors and recruitment of coactivators to create functional complexes that are bound to consensus promoter DNA sequences called retinoic acid response elements (RAREs) and that cause opening of chromatin and transcription of adjacent genes. Homologous recombination technology allowed the development of mice lacking expression of retinoic acid receptors, individually or in various combinations, which demonstrated that the receptors exhibit vital, but redundant, functions in fetal development and in vision, reproduction, and other functions required for maintenance of adult life. More recent advancements in sequencing and proteomic technologies reveal the complexity of retinoic acid receptor involvement in cellular function through regulation of gene expression and kinase activity. Future directions will require systems biology approaches to decipher how these integrated networks affect human stem cells, health, and disease.
    Sub-cellular biochemistry 05/2014; 70:1-20. DOI:10.1007/978-94-017-9050-5_1
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    ABSTRACT: Objective There is a lack of reliable indicators to predict who will benefit most from anti-angiogenic therapy, such as bevacizumab. Recognizing obesity is associated with increased levels of VEGF, the main target of bevacizumab, we sought to assess if adiposity, measured in terms of BMI, subcutaneous fat area (SFA), and visceral fat area (VFA) was prognostic. Methods Reviewed 46 patients with advanced EOC who received primary treatment with bevacizumab-based chemotherapy (N = 21) or chemotherapy alone (N = 25) for whom complete records, CT prior to the first cycle of chemo, and serum were available. CT was used to measure SFA and VFA by radiologists blinded to outcomes. ELISA was used to measure serum levels of VEGF and angiopoietin-2 in the bevacizumab group. Results BMI, SFA, and VFA were dichotomized using the median and categorized as “high” or “low”. In the bevacizumab group median PFS was shorter for patients with high BMI (9.8 vs. 24.7 months, p = 0.03), while in the chemotherapy group median PFS was similar between high and low BMI (17.6 vs. 11.9 months, p = 0.19). In the bevacizumab group patients with a high BMI had higher median levels of VEGF and angiopoietin-2, 371.9 vs. 191.4 pg/ml (p = 0.05) and 45.9 vs. 16.6 pg/ml (p = 0.09) respectively. On multivariate analysis neither BMI, SFA, nor VFA were associated with PFS (p = 0.13, p = 0.86, p = 0.16 respectively) or OS (p = 0.14, p = 0.93, p = 0.28 respectively) in the chemotherapy group. However, in the bevacizumab group BMI was significantly associated with PFS (p = 0.02); accounting for confounders adjusted HR for high vs. low BMI was 5.16 (95% CI 1.31–20.24). Additionally in the bevacizumab group SFA was significantly associated with OS (p = 0.03); accounting for confounders adjusted HR for high vs. low SFA was 3.58 (95% CI 1.12–11.43). Conclusion Results provide the first evidence in EOC that patients with high levels of adiposity may not derive benefit from bevacizumab and that measurements of adiposity are likely to be a useful biomarker.
    Gynecologic Oncology 04/2014; 133(1):11–15. DOI:10.1016/j.ygyno.2014.01.031 · 3.77 Impact Factor
  • Erin A Bishop · Stan Lightfoot · Elangovan Thavathiru · Doris Mangiaracina Benbrook ·
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    ABSTRACT: Epidemiological studies suggest an association between elevated insulin levels and endometrial cancer. We studied the effects of insulin on normal endometrial cell proliferation with cytotoxicity assays. Organotypic cultures were used to determine the effects of insulin on the development of malignant histological features and anchorage independent growth. Western Blots were used to analyze the mitogen-activated protein kinases and AKT pathways. We found that insulin exerts direct effects on endometrial cells by increasing proliferation and promoting carcinogenesis. Our results suggest that this occurs through ERK 1/2 and glycogen synthase kinase-3β Ser9 phosphorylation.
    Cancer Investigation 03/2014; 32(3):63-70. DOI:10.3109/07357907.2013.877479 · 2.22 Impact Factor
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    ABSTRACT: SHetA2 is a small molecule flexible heteroarotinoid (Flex-Het) with promising cancer prevention and therapeutic activity. Extensive preclinical testing documented lack of SHetA2 toxicity at doses 25 to 150 fold above effective doses. Knowledge of the SHetA2 molecular target(s) that mediate(s) the mechanism of SHetA2 action is critical to appropriate design of clinical trials and improved analogs. The aim of this study was to develop a method to identify SHetA2 binding proteins in cancer cells. A known metabolite of SHetA2 that has a hydroxyl group available for attachment was synthesized and conjugated to a linker for attachment to a magnetic microsphere. SHetA2-conjugated magnetic microspheres and unconjugated magnetic microspheres were separately incubated with aliquots of a whole cell protein extract from the A2780 human ovarian cancer cell line. After washing away non-specifically bound proteins with the protein extraction buffer, SHetA2-binding proteins were eluted with an excess of free SHetA2. In two independent experiments, an SDS gel band of about 72 kDa was present at differential levels in wells of eluent from SHetA2-microspheres in comparison to wells of eluent from unconjugated microspheres. Mass spectrometry analysis of the bands (QStar) and straight eluents (Orbitrap) identified mortalin (HSPA9) to be present in the eluent from SHetA2-microspheres and not in eluent from unconjugated microspheres. Co-immunoprecipitation experiments demonstrated that SHetA2 interfered with mortalin binding to p53 and p66 Src homologous-collagen homologue (p66shc) inside cancer cells. Mortalin and SHetA2 conflictingly regulate the same molecules involved in mitochondria-mediated intrinsic apoptosis. The results validate the power of this protocol for revealing drug targets. Electronic supplementary material The online version of this article (doi:10.1007/s10637-013-0041-x) contains supplementary material, which is available to authorized users.
    Investigational New Drugs 11/2013; 32(3). DOI:10.1007/s10637-013-0041-x · 2.92 Impact Factor
  • Stan Lightfoot · Daniel Zhao · Elangovan Thavathiru · Doris Mangiaracina Benbrook ·

    Cancer Research 08/2013; 73(8 Supplement):3703-3703. DOI:10.1158/1538-7445.AM2013-3703 · 9.33 Impact Factor
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    ABSTRACT: The occurrence of intestinal polyps in people at high risk for developing colorectal cancer provides an opportunity to test the efficacy of chemoprevention agents. In this situation of treating otherwise healthy people, the potential for toxicity must be minimal. The small molecule flexible heteroarotinoid (Flex-Het), called SHetA2, has chemoprevention activity in organotypic cultures in vitro and lack of toxicity at doses capable of inhibiting xenograft tumor growth in vivo. The objective of this study was to evaluate SHetA2 chemoprevention activity and toxicity in the APCMin/+ murine model. Oral administration of SHetA2 at 30 and 60 mg/kg five days per week for 12 weeks significantly reduced development of intestinal polyps by 40 to 60% depending on the dose and sex of the treatment group. Immunohistochemical and Western blot analysis of polyps demonstrated reduced levels of cyclin D1 and proliferating cell nuclear antigen (PCNA) in both SHetA2 treatment groups. Western blot analysis also demonstrated SHetA2 induction of E-cadherin, Bax and caspase 3 cleavage along with reduction in Bcl-2, cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF), consistent with SHetA2 regulation of apoptosis, inflammation and angiogenesis. Neither dose caused weight loss nor gross toxicity in APCMin/+ or wild type littermates. Magnetic resonance imaging (MRI) of cardiac function showed no evidence of SHetA2 toxicity. SHetA2 did not alter left ventricular wall thickness. In summary, SHetA2 exerts chemoprevention activity without overt or cardiac toxicity in the APCMin/+ model. SHetA2 modulation of biomarkers in colon polyps identifies potential pharmacodynamic endpoints for SHetA2 clinical trials.
    Cancer Prevention Research 07/2013; 6(9). DOI:10.1158/1940-6207.CAPR-13-0171 · 4.44 Impact Factor
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    ABSTRACT: Objective: This study aims to assess the role of polymorphisms in DNA repair genes, excision repair cross-complementation group 1 (ERCC1) and methyl-methanesulfonate sensitivity 19 (MMS19), in tumor response to platinum-based chemotherapy and survival in advanced epithelial ovarian cancer (EOC). Methods: Single nucleotide polymorphism (SNP) analysis was performed on the paraffin-embedded tumor tissue of women with advanced EOC, treated with platinum-based chemotherapy at the University of Oklahoma Health Sciences Center. Polymorphisms from two ERCC1 (codon-118 and C8092A) and three MMS19 (rs2211243, rs2236575 and rs872106) gene loci were evaluated by real time PCR Allelic Discrimination Assay. Results: Genotyping was performed in 107 patients, 45 platinum-sensitive and 62 platinum-resistant. ERCC1, codon-118 and C8092A genotyping was evaluable in 98 and 106 patients respectively and in all 107 patients for MMS19 polymorphisms. No differences were observed in genotype between platinum-sensitive and platinum-resistant patients. Polymorphisms in the ERCC1, codon-118 and MMS19 genes did not correlate with overall survival (OS), although a trend toward improved progression free survival (PFS) was observed in patients expressing the minor (GG) alleles of the rs872106 MMS19 gene. Women homozygous for the ERCC1-C8092A minor (AA) alleles had a significant increase in PFS compared to AC and CC patients and both AA and AC genotypes conferred improved survival over the major (CC) genotype. Conclusions: Polymorphisms in ERCC1, codon-118 and MMS19 genes are not associated with clinical response to platinum or survival. The ERCC1-C8092A genotypes containing an "A" allele were associated with significant improvement in PFS and OS strengthening the value of this specific genotype in survival.
    Gynecologic Oncology 04/2013; 130(2). DOI:10.1016/j.ygyno.2013.04.054 · 3.77 Impact Factor
  • Mark F. Naylor · David M. Thompson · Stan Lightfoot · Doris Mangiaracina Benbrook ·

    Journal of Cancer Therapy 01/2013; 04(06):7-19. DOI:10.4236/jct.2013.46A1002
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    D M Benbrook · A Long ·
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    ABSTRACT: A single cell has the potential to kill an entire human being. Efforts to cure cancer are limited by survival of individual cancer cells despite immune surveillance and toxic therapies. Understanding the intricate network of pathways that maintain cellular homeostasis and mediate stress response or default into cell death is critical to the development of strategies to eradicate cancer. Autophagy, proteasomal degradation and the unfolded protein response (UPR) are cellular pathways that degrade and recycle excess or damaged proteins to maintain cellular homeostasis and survival. This review will discuss autophagy and how it is integrated with proteasomal degradation and UPR to govern cell fate through restoration of cellular homeostasis or default into the apoptotic cell death pathway. The first response of autophagy is macroautophagy, which sequesters cytoplasm including organelles inside double-membraned autophagosome vesicles that fuse with lysosomes to degrade and recycle the contents. Ubiquitination patterns on proteins targeted for degradation determine whether adapter proteins will bring them to developing autophagosomes or to proteasomes. Macroautophagy is followed by chaperone-mediated autophagy (CMA), in which Hsc70 (Heat shock cognate 70) selectively binds proteins with exposed KFERQ motifs and pushes them inside lysosomes through the LAMP-2A (Lysosome-associated membrane protein type 2A) receptor. These two processes and the lesser understood microautophagy, which involves direct engulfment of proteins into lysosomes, occur at basal and induced levels. Insufficient proteasome function or ER stress induction of UPR can induce autophagy, which can mitigate damage and stress. If this network is incapable of repairing the damage or overcoming continued stress, the default pathway of apoptosis is engaged to destroy the cell. Induction of macroautophagy by cancer therapeutics has led to clinical trials investigating combinations of HCQ (hydroxychloriquine) suppression of autophagy with apoptosis-inducing agents. Further study of the complex integration of autophagy, proteasomal degradation, UPR and apoptosis is likely to provide additional targets for our fight against cancer. This article is part of a Special Issue entitled "Apoptosis: Four Decades Later".
    Experimental oncology 10/2012; 34(3):286-97.
  • E. Nugent · A. Long · C. Mathews · E. Bishop · K. Moxley · D. Benbrook · R. Wild · D. McMeekin ·

    Gynecologic Oncology 10/2012; 127(1):S7–S8. DOI:10.1016/j.ygyno.2012.07.021 · 3.77 Impact Factor
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    ABSTRACT: SHetA2 is a heteroarotinoid that has shown selective inhibition of cancer cell growth and an induction of apoptosis without activation of nuclear retinoic acid receptors. In the rat study, SHetA2 was administered in 1% aqueous methylcellulose/0.2% Tween 80 by oral gavage at 0, 100, 500, and 2,000 mg/kg/day for 28 days. The high-dose administration induced decreased activity in male rats, decreased body-weight gains and food consumption, and changes in organ weights. The major metabolite of SHetA2 in rat plasma was monohydroxy SHetA2, which was considerably higher than the parent compound after oral and intravenous administration. Pharmacokinetic analysis showed extremely low (<1%) systemic bioavailability of SHetA2 for all doses tested. The dose of 2,000 mg/kg/day was considered as the lowest observed adverse effect level. The no observed adverse effect level (NOAEL) was 500 mg/kg/day. In the dog study, no toxicity of SHetA2 in 30% aqueous Solutol(®) HS 15 was observed in any tested dose groups (0, 100, 400, and 1,500 mg/kg/day). The major metabolite of SHetA2 in dog plasma was also monohydroxy SHetA2, which was equal to or lower than the parent compound after oral administration. SHetA2 levels in dog plasma were notably higher, when compared to levels in rat plasma. However, exposure was not dose proportional, as exemplified by a lack of proportional increase in maximum concentration or area under the plasma concentration-time curve with increasing dose. The NOAEL was not established and was considered to be above 1,500 mg/kg/day.
    Drug and Chemical Toxicology 09/2012; 36(3). DOI:10.3109/01480545.2012.710632 · 1.23 Impact Factor
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    ABSTRACT: To evaluate the efficacy and adverse events of thalidomide in previously-treated, measurable, persistent or recurrent carcinosarcoma of the uterus, and to explore associations between angiogenic markers with patient demographics and clinical outcome. Eligible, consenting patients were treated until disease progression or toxicity intervened with daily starting dose of 200mg thalidomide/day that was increased by 200mg every 2weeks to a target dose of 1000mg/day. Endpoints included progression-free survival (PFS)≥6months (primary), toxicity, response, overall PFS and survival. Pre- and post-treatment plasma were evaluated for a panel of angiogenic biomarkers and assessed against clinical outcomes. Of 55 enrolled patients, 45 were evaluable for toxicity and survival. Two patients (4%; 90% CI 1-13%) experienced a partial response, and 8 (18%; 90% CI 9-30%) had PFS≥6months. Median PFS was 1.9months and median survival was 5.9months. Grade 2-3 sensory neuropathy was noted in 6 patients, and 4, 3, and 3 patients experienced grade 3 sedation, fatigue, and constipation, respectively. Three patients had grade 4 adverse events (2 thromboembolic, 1 anemia). High pre-treatment VEGFA levels were associated with poorer PFS and survival. Treatment with thalidomide met the protocol specified goal of prolonging PFS at 6months. However, based on results with newer agents, the activity was insufficient to support further investigation. Association between pre-treatment VEGFA and prognosis in this population supports further evaluation of anti-angiogenic therapies in uterine carcinosarcoma.
    Gynecologic Oncology 07/2012; 127(2):356-61. DOI:10.1016/j.ygyno.2012.07.095 · 3.77 Impact Factor

  • Cancer Research 06/2012; 72(8 Supplement):4781-4781. DOI:10.1158/1538-7445.AM2012-4781 · 9.33 Impact Factor
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    BMC proceedings 06/2012; 6(3). DOI:10.1186/1753-6561-6-S3-P56

Publication Stats

2k Citations
425.46 Total Impact Points


  • 1997-2015
    • Oklahoma City University
      Oklahoma City, Oklahoma, United States
  • 1994-2015
    • University of Oklahoma Health Sciences Center
      • • Department of Obstetrics and Gynecology
      • • Department of Biochemistry and Molecular Biology
      • • Section of Gynecologic Oncology
      • • Department of Urology
      Oklahoma City, Oklahoma, United States
  • 2006-2011
    • University of Oklahoma
      • Department of Obstetrics and Gynecology
      Norman, OK, United States
    • The University of Hong Kong
      • Department of Pathology
      Hong Kong, Hong Kong
  • 1998-2005
    • Oklahoma State University - Stillwater
      • Department of Chemistry
      Stillwater, Oklahoma, United States
  • 2002
    • National Cancer Institute (USA)
      베서스다, Maryland, United States
  • 2001
    • Università degli Studi di Palermo
      Palermo, Sicily, Italy
  • 1987
    • Fred Hutchinson Cancer Research Center
      Seattle, Washington, United States