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Hirst JE, Boniface JJ, Le DP, Polpitiya AD, Fox AC, Vu TTK, Dang TT, Fleischer TC, Bui NTH, Hickok DE, Kearney PE, Thwaites G, Kennedy SH, Kestelyn E, Le TQ. Validating the ratio of insulin like growth factor binding protein 4 to sex hormone binding globulin as a prognostic predictor of preterm birth in Viet Nam: a case-cohort study. J Matern Fetal Neonatal Med 2024; 37:2333923. [PMID: 38584143 DOI: 10.1080/14767058.2024.2333923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 03/13/2024] [Indexed: 04/09/2024]
Abstract
OBJECTIVE To validate a serum biomarker developed in the USA for preterm birth (PTB) risk stratification in Viet Nam. METHODS Women with singleton pregnancies (n = 5000) were recruited between 19+0-23+6 weeks' gestation at Tu Du Hospital, Ho Chi Minh City. Maternal serum was collected from 19+0-22+6 weeks' gestation and participants followed to neonatal discharge. Relative insulin-like growth factor binding protein 4 (IGFBP4) and sex hormone binding globulin (SHBG) abundances were measured by mass spectrometry and their ratio compared between PTB cases and term controls. Discrimination (area under the receiver operating characteristic curve, AUC) and calibration for PTB <37 and <34 weeks' gestation were tested, with model tuning using clinical factors. Measured outcomes included all PTBs (any birth ≤37 weeks' gestation) and spontaneous PTBs (birth ≤37 weeks' gestation with clinical signs of initiation of parturition). RESULTS Complete data were available for 4984 (99.7%) individuals. The cohort PTB rate was 6.7% (n = 335). We observed an inverse association between the IGFBP4/SHBG ratio and gestational age at birth (p = 0.017; AUC 0.60 [95% CI, 0.53-0.68]). Including previous PTB (for multiparous women) or prior miscarriage (for primiparous women) improved performance (AUC 0.65 and 0.70, respectively, for PTB <37 and <34 weeks' gestation). Optimal performance (AUC 0.74) was seen within 19-20 weeks' gestation, for BMI >21 kg/m2 and age 20-35 years. CONCLUSION We have validated a novel serum biomarker for PTB risk stratification in a very different setting to the original study. Further research is required to determine appropriate ratio thresholds based on the prevalence of risk factors and the availability of resources and preventative therapies.
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Affiliation(s)
- Jane E Hirst
- Department of Global Women's Health, The George Institute for Global Health, Imperial College London, London, UK
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Women's Centre, John Radcliffe Hospital, Oxford, UK
| | | | - Dung Puhong Le
- Department of Obstetrics and Gynaecology, Tu Du Hospital, Ho Chi Minh City, Viet Nam
| | | | - Angela C Fox
- Sera Prognostics, Inc, Salt Lake City, Utah, USA
| | - Thi Thai Kim Vu
- Clinical Trials Unit, Oxford University Clinical Research Unit, Ho Chi Minh City, Viet Nam
| | - Thuan Trong Dang
- Clinical Trials Unit, Oxford University Clinical Research Unit, Ho Chi Minh City, Viet Nam
| | | | - Nhu Thi Hong Bui
- Department of Obstetrics and Gynaecology, Tu Du Hospital, Ho Chi Minh City, Viet Nam
| | | | | | - Guy Thwaites
- Clinical Trials Unit, Oxford University Clinical Research Unit, Ho Chi Minh City, Viet Nam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Stephen H Kennedy
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Women's Centre, John Radcliffe Hospital, Oxford, UK
| | - Evelyne Kestelyn
- Clinical Trials Unit, Oxford University Clinical Research Unit, Ho Chi Minh City, Viet Nam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Thanh Quang Le
- Department of Obstetrics and Gynaecology, Tu Du Hospital, Ho Chi Minh City, Viet Nam
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Bradford C, Severinsen R, Pugmire T, Rasmussen M, Stoddard K, Uemura Y, Wheelwright S, Mentinova M, Chelsky D, Hunsucker SW, Kearney P, Hickok D, Fleischer TC, Ichetovkin I, Boniface JJ, Critchfield GC, Peltier JM. Corrigendum to “Analytical validation of protein biomarkers for risk of spontaneous preterm birth” [Clin. Mass Spectrom. 3 (2017) 25–38]. J Mass Spectrom Adv Clin Lab 2022; 25:71. [PMID: 35969710 PMCID: PMC9372730 DOI: 10.1016/j.jmsacl.2022.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Burchard J, Saade GR, Boggess KA, Markenson GR, Iams JD, Coonrod DV, Pereira LM, Hoffman MK, Polpitiya AD, Treacy R, Fox AC, Randolph TL, Fleischer TC, Dufford MT, Garite TJ, Critchfield GC, Boniface JJ, Kearney PE. Better Estimation of Spontaneous Preterm Birth Prediction Performance through Improved Gestational Age Dating. J Clin Med 2022; 11:jcm11102885. [PMID: 35629011 PMCID: PMC9146613 DOI: 10.3390/jcm11102885] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/11/2022] [Accepted: 05/18/2022] [Indexed: 02/05/2023] Open
Abstract
The clinical management of pregnancy and spontaneous preterm birth (sPTB) relies on estimates of gestational age (GA). Our objective was to evaluate the effect of GA dating uncertainty on the observed performance of a validated proteomic biomarker risk predictor, and then to test the generalizability of that effect in a broader range of GA at blood draw. In a secondary analysis of a prospective clinical trial (PAPR; NCT01371019), we compared two GA dating categories: both ultrasound and dating by last menstrual period (LMP) (all subjects) and excluding dating by LMP (excluding LMP). The risk predictor's performance was observed at the validated risk predictor threshold both in weeks 191/7-206/7 and extended to weeks 180/7-206/7. Strict blinding and independent statistical analyses were employed. The validated biomarker risk predictor showed greater observed sensitivity of 88% at 75% specificity (increases of 17% and 1%) in more reliably dated (excluding-LMP) subjects, relative to all subjects. Excluding dating by LMP significantly improved the sensitivity in weeks 191/7-206/7. In the broader blood draw window, the previously validated risk predictor threshold significantly stratified higher and lower risk of sPTB, and the risk predictor again showed significantly greater observed sensitivity in excluding-LMP subjects. These findings have implications for testing the performance of models aimed at predicting PTB.
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Affiliation(s)
- Julja Burchard
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
- Correspondence: ; Tel.: +1-801-990-0597
| | - George R. Saade
- Department of Obstetrics & Gynecology, The University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Kim A. Boggess
- Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, University of North Carolina, Chapel Hill, NC 27599, USA;
| | - Glenn R. Markenson
- Maternal Fetal Medicine, Boston University School of Medicine, Boston, MA 02118, USA;
| | - Jay D. Iams
- Department of Obstetrics & Gynecology, The Ohio State University, Columbus, OH 43210, USA;
| | - Dean V. Coonrod
- Department of Obstetrics and Gynecology, Valleywise Health, Phoenix, AZ 85008, USA;
| | - Leonardo M. Pereira
- Division of Maternal-Fetal Medicine, Oregon Health & Science University, Portland, OR 97239, USA;
| | - Matthew K. Hoffman
- Department of Obstetrics & Gynecology, Christiana Care Health System, Newark, DE 19718, USA;
| | - Ashoka D. Polpitiya
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Ryan Treacy
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Angela C. Fox
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Todd L. Randolph
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Tracey C. Fleischer
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Max T. Dufford
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Thomas J. Garite
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Gregory C. Critchfield
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - J. Jay Boniface
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Paul E. Kearney
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (A.D.P.); (R.T.); (A.C.F.); (T.L.R.); (T.C.F.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
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Burchard J, Markenson GR, Saade GR, Laurent LC, Heyborne KD, Coonrod DV, Schoen CN, Baxter JK, Haas DM, Longo SA, Sullivan SA, Wheeler SM, Pereira LM, Boggess KA, Hawk AF, Crockett AH, Treacy R, Fox AC, Polpitiya AD, Fleischer TC, Garite TJ, Jay Boniface J, Zupancic JAF, Critchfield GC, Kearney PE. Clinical and economic evaluation of a proteomic biomarker preterm birth risk predictor: cost-effectiveness modeling of prenatal interventions applied to predicted higher-risk pregnancies within a large and diverse cohort. J Med Econ 2022; 25:1255-1266. [PMID: 36377363 DOI: 10.1080/13696998.2022.2147771] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES Preterm birth occurs in more than 10% of U.S. births and is the leading cause of U.S. neonatal deaths, with estimated annual costs exceeding $25 billion USD. Using real-world data, we modeled the potential clinical and economic utility of a prematurity-reduction program comprising screening in a racially and ethnically diverse population with a validated proteomic biomarker risk predictor, followed by case management with or without pharmacological treatment. METHODS The ACCORDANT microsimulation model used individual patient data from a prespecified, randomly selected sub-cohort (N = 847) of a multicenter, observational study of U.S. subjects receiving standard obstetric care with masked risk predictor assessment (TREETOP; NCT02787213). All subjects were included in three arms across 500 simulated trials: standard of care (SoC, control); risk predictor/case management comprising increased outreach, education and specialist care (RP-CM, active); and multimodal management (risk predictor/case management with pharmacological treatment) (RP-MM, active). In the active arms, only subjects stratified as higher risk by the predictor were modeled as receiving the intervention, whereas lower-risk subjects received standard care. Higher-risk subjects' gestational ages at birth were shifted based on published efficacies, and dependent outcomes, calibrated using national datasets, were changed accordingly. Subjects otherwise retained their original TREETOP outcomes. Arms were compared using survival analysis for neonatal and maternal hospital length of stay, bootstrap intervals for neonatal cost, and Fisher's exact test for neonatal morbidity/mortality (significance, p < .05). RESULTS The model predicted improvements for all outcomes. RP-CM decreased neonatal and maternal hospital stay by 19% (p = .029) and 8.5% (p = .001), respectively; neonatal costs' point estimate by 16% (p = .098); and moderate-to-severe neonatal morbidity/mortality by 29% (p = .025). RP-MM strengthened observed reductions and significance. Point estimates of benefit did not differ by race/ethnicity. CONCLUSIONS Modeled evaluation of a biomarker-based test-and-treat strategy in a diverse population predicts clinically and economically meaningful improvements in neonatal and maternal outcomes.
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Affiliation(s)
| | - Glenn R Markenson
- Department of Obstetrics and Gynecology, Boston University School of Medicine, Boston, MA, USA
| | - George R Saade
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX, USA
| | - Louise C Laurent
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Diego, CA, USA
| | - Kent D Heyborne
- Department of Obstetrics and Gynecology, Denver Health and Hospital Authority, Denver, CO, and Department of Obstetrics and Gynecology, University of Colorado Denver, Aurora, CO, USA
| | - Dean V Coonrod
- Department of Obstetrics and Gynecology, Valleywise Health, and Department of Obstetrics and Gynecology, University of Arizona College of Medicine, Phoenix, AZ, USA
| | - Corina N Schoen
- Department of Obstetrics and Gynecology, University of Massachusetts-Baystate, Springfield, MA, USA
| | - Jason K Baxter
- Department of Obstetrics and Gynecology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - David M Haas
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Sherri A Longo
- Department of Obstetrics and Gynecology, Ochsner Health, New Orleans, LA, USA
| | - Scott A Sullivan
- Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC, USA
| | - Sarahn M Wheeler
- Department of Obstetrics and Gynecology, Duke University School of Medicine, Durham, NC, USA
| | - Leonardo M Pereira
- Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR, USA
| | - Kim A Boggess
- Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Angela F Hawk
- Regional Obstetrical Consultants, Chattanooga, TN, USA
| | - Amy H Crockett
- Department of Obstetrics and Gynecology, University of South Carolina School of Medicine Greenville and Prisma Health-Upstate, Greenville, SC, USA
| | - Ryan Treacy
- Sera Prognostics, Inc, Salt Lake City, UT, USA
| | | | | | | | | | | | - John A F Zupancic
- Department of Pediatrics, Harvard Medical School, and Department of Neonatology, Beth Israel Deaconess Medical Center, Boston, MA, USA
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5
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Khanam R, Fleischer TC, Boghossian NS, Nisar I, Dhingra U, Rahman S, Fox AC, Ilyas M, Dutta A, Naher N, Polpitiya AD, Mehmood U, Deb S, Choudhury AA, Badsha MB, Muhammad K, Ali SM, Ahmed S, Hickok DE, Iqbal N, Juma MH, Quaiyum MA, Boniface JJ, Yoshida S, Manu A, Bahl R, Jehan F, Sazawal S, Burchard J, Baqui AH. Performance of a validated spontaneous preterm delivery predictor in South Asian and Sub-Saharan African women: a nested case control study. J Matern Fetal Neonatal Med 2021; 35:8878-8886. [PMID: 34847802 DOI: 10.1080/14767058.2021.2005573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVES To address the disproportionate burden of preterm birth (PTB) in low- and middle-income countries, this study aimed to (1) verify the performance of the United States-validated spontaneous PTB (sPTB) predictor, comprised of the IBP4/SHBG protein ratio, in subjects from Bangladesh, Pakistan and Tanzania enrolled in the Alliance for Maternal and Newborn Health Improvement (AMANHI) biorepository study, and (2) discover biomarkers that improve performance of IBP4/SHBG in the AMANHI cohort. STUDY DESIGN The performance of the IBP4/SHBG biomarker was first evaluated in a nested case control validation study, then utilized in a follow-on discovery study performed on the same samples. Levels of serum proteins were measured by targeted mass spectrometry. Differences between the AMANHI and U.S. cohorts were adjusted using body mass index (BMI) and gestational age (GA) at blood draw as covariates. Prediction of sPTB < 37 weeks and < 34 weeks was assessed by area under the receiver operator curve (AUC). In the discovery phase, an artificial intelligence method selected additional protein biomarkers complementary to IBP4/SHBG in the AMANHI cohort. RESULTS The IBP4/SHBG biomarker significantly predicted sPTB < 37 weeks (n = 88 vs. 171 terms ≥ 37 weeks) after adjusting for BMI and GA at blood draw (AUC= 0.64, 95% CI: 0.57-0.71, p < .001). Performance was similar for sPTB < 34 weeks (n = 17 vs. 184 ≥ 34 weeks): AUC = 0.66, 95% CI: 0.51-0.82, p = .012. The discovery phase of the study showed that the addition of endoglin, prolactin, and tetranectin to the above model resulted in the prediction of sPTB < 37 with an AUC= 0.72 (95% CI: 0.66-0.79, p-value < .001) and prediction of sPTB < 34 with an AUC of 0.78 (95% CI: 0.67-0.90, p < .001). CONCLUSION A protein biomarker pair developed in the U.S. may have broader application in diverse non-U.S. populations.
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Affiliation(s)
- Rasheda Khanam
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, United States
| | | | - Nansi S Boghossian
- Department of Epidemiology and Biostatistics, University of South Carolina, Arnold School of Public Health, Columbia, United States
| | - Imran Nisar
- Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | - Usha Dhingra
- Global Division, Center for Public Health Kinetics, New Delhi, India
| | | | - Angela C Fox
- Sera Prognostics, Inc., Salt Lake City, United States
| | - Muhammad Ilyas
- Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | - Arup Dutta
- Global Division, Center for Public Health Kinetics, New Delhi, India
| | - Nurun Naher
- Projahnmo Research Foundation, Dhaka, Bangladesh
| | | | - Usma Mehmood
- Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | - Saikat Deb
- Global Division, Center for Public Health Kinetics, New Delhi, India.,Public Health Laboratory-IDC, Pemba, Tanzania
| | | | | | - Karim Muhammad
- Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | | | | | | | - Najeeha Iqbal
- Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | | | - Md Abdul Quaiyum
- International Centre for Diarrheal Disease Research, Dhaka, Bangladesh
| | | | | | - Alexandar Manu
- World Health Organization (MCA/MRD), Geneva, Switzerland
| | - Rajiv Bahl
- World Health Organization (MCA/MRD), Geneva, Switzerland
| | - Fyezah Jehan
- Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | - Sunil Sazawal
- Global Division, Center for Public Health Kinetics, New Delhi, India.,Public Health Laboratory-IDC, Pemba, Tanzania
| | | | - Abdullah H Baqui
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, United States
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Burchard J, Polpitiya AD, Fox AC, Randolph TL, Fleischer TC, Dufford MT, Garite TJ, Critchfield GC, Boniface JJ, Saade GR, Kearney PE. Clinical Validation of a Proteomic Biomarker Threshold for Increased Risk of Spontaneous Preterm Birth and Associated Clinical Outcomes: A Replication Study. J Clin Med 2021; 10:5088. [PMID: 34768605 PMCID: PMC8584743 DOI: 10.3390/jcm10215088] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 12/22/2022] Open
Abstract
Preterm births are the leading cause of neonatal death in the United States. Previously, a spontaneous preterm birth (sPTB) predictor based on the ratio of two proteins, IBP4/SHBG, was validated as a predictor of sPTB in the Proteomic Assessment of Preterm Risk (PAPR) study. In particular, a proteomic biomarker threshold of -1.37, corresponding to a ~two-fold increase or ~15% risk of sPTB, significantly stratified earlier deliveries. Guidelines for molecular tests advise replication in a second independent study. Here we tested whether the significant association between proteomic biomarker scores above the threshold and sPTB, and associated adverse outcomes, was replicated in a second independent study, the Multicenter Assessment of a Spontaneous Preterm Birth Risk Predictor (TREETOP). The threshold significantly stratified subjects in PAPR and TREETOP for sPTB (p = 0.041, p = 0.041, respectively). Application of the threshold in a Kaplan-Meier analysis demonstrated significant stratification in each study, respectively, for gestational age at birth (p < 001, p = 0.0016) and rate of hospital discharge for both neonate (p < 0.001, p = 0.005) and mother (p < 0.001, p < 0.001). Above the threshold, severe neonatal morbidity/mortality and mortality alone were 2.2 (p = 0.0083,) and 7.4-fold higher (p = 0.018), respectively, in both studies combined. Thus, higher predictor scores were associated with multiple adverse pregnancy outcomes.
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Affiliation(s)
- Julja Burchard
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Ashoka D. Polpitiya
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Angela C. Fox
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Todd L. Randolph
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Tracey C. Fleischer
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Max T. Dufford
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Thomas J. Garite
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - Gregory C. Critchfield
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - J. Jay Boniface
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
| | - George R. Saade
- Department of Obstetrics & Gynecology, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Paul E. Kearney
- Sera Prognostics, Incorporated, Salt Lake City, UT 84109, USA; (J.B.); (A.D.P.); (A.C.F.); (T.L.R.); (M.T.D.); (T.J.G.); (G.C.C.); (J.J.B.); (P.E.K.)
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7
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Markenson GR, Saade GR, Laurent LC, Heyborne KD, Coonrod DV, Schoen CN, Baxter JK, Haas DM, Longo S, Grobman WA, Sullivan SA, Major CA, Wheeler SM, Pereira LM, Su EJ, Boggess KA, Hawk AF, Crockett AH, Fox AC, Polpitiya A, Fleischer TC, Critchfield GC, Burchard J, Boniface JJ, Lam GK. Performance of a proteomic preterm delivery predictor in a large independent prospective cohort. Am J Obstet Gynecol MFM 2020; 2:100140. [PMID: 33345877 DOI: 10.1016/j.ajogmf.2020.100140] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/05/2020] [Accepted: 05/06/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND Preterm birth remains a common and devastating complication of pregnancy. There remains a need for effective and accurate screening methods for preterm birth. Using a proteomic approach, we previously discovered and validated (Proteomic Assessment of Preterm Risk study, NCT01371019) a preterm birth predictor comprising a ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin. OBJECTIVE To determine the performance of the ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin to predict both spontaneous and medically indicated very preterm births, in an independent cohort distinct from the one in which it was developed. STUDY DESIGN This was a prospective observational study (Multicenter Assessment of a Spontaneous Preterm Birth Risk Predictor, NCT02787213) at 18 sites in the United States. Women had blood drawn at 170/7 to 216/7 weeks' gestation. For confirmation, we planned to analyze a randomly selected subgroup of women having blood drawn between 191/7 and 206/7 weeks' gestation, with the results of the remaining study participants blinded for future validation studies. Serum from participants was analyzed by mass spectrometry. Neonatal morbidity and mortality were analyzed using a composite score by a method from the PREGNANT trial (NCT00615550, Hassan et al). Scores of 0-3 reflect increasing numbers of morbidities or length of neonatal intensive care unit stay, and 4 represents perinatal mortality. RESULTS A total of 5011 women were enrolled, with 847 included in this planned substudy analysis. There were 9 preterm birth cases at <320/7 weeks' gestation and 838 noncases at ≥320/7 weeks' gestation; 21 of 847 infants had neonatal composite morbidity and mortality index scores of ≥3, and 4 of 21 had a score of 4. The ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio was substantially higher in both preterm births at <320/7 weeks' gestation and there were more severe neonatal outcomes. The ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio was significantly predictive of birth at <320/7 weeks' gestation (area under the receiver operating characteristic curve, 0.71; 95% confidence interval, 0.55-0.87; P=.016). Stratification by body mass index, optimized in the previous validation study (22<body mass index≤37 kg/m2), resulted in an area under the receiver operating characteristic curve of 0.76 (95% confidence interval, 0.59-0.93; P=.023). The ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio predicted neonatal outcomes with respective area under the receiver operating characteristic curve of 0.67 (95% confidence interval, 0.57-0.77; P=.005) and 0.78 (95% confidence interval, 0.63-0.93; P=.026) for neonatal composite morbidity and mortality scores of ≥3 or 4. In addition, the ratio of insulin-like growth factor-binding protein 4 to sex hormone binding globulin significantly stratified neonates with increased length of hospital stay (log rank P=.023). CONCLUSION We confirmed in an independent cohort the ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin ratio as a predictor of very preterm birth, with additional prediction of increased length of neonatal hospital stay and increased severity of adverse neonatal outcomes. Potential uses of the ratio of insulin-like growth factor-binding protein 4 to sex hormone-binding globulin predictor may be to risk stratify patients for implementation of preterm birth preventive strategies and direct patients to appropriate levels of care.
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Affiliation(s)
- Glenn R Markenson
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Boston Medical Center, Boston, MA
| | - George R Saade
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX
| | - Louise C Laurent
- Division of Maternal-Fetal Medicine, Department of Reproductive Sciences, University of California, San Diego, CA
| | - Kent D Heyborne
- Department of Obstetrics and Gynecology, Denver Health and Hospital Authority
| | - Dean V Coonrod
- Department of Obstetrics and Gynecology, Maricopa Integrated Health System
| | - Corina N Schoen
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Massachusetts-Baystate
| | - Jason K Baxter
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Thomas Jefferson University Hospital
| | - David M Haas
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Indiana University
| | - Sherri Longo
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Ochsner Baptist Medical Center, New Orleans, LA
| | - William A Grobman
- Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL
| | - Scott A Sullivan
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC
| | - Carol A Major
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Irvine, CA
| | - Sarahn M Wheeler
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University, Durham, NC
| | - Leonardo M Pereira
- Division Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR
| | - Emily J Su
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora, CO
| | - Kim A Boggess
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, NC
| | | | - Amy H Crockett
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Greenville Health System, Greenville, SC
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Link AJ, Niu X, Weaver CM, Jennings JL, Duncan DT, McAfee KJ, Sammons M, Gerbasi VR, Farley AR, Fleischer TC, Browne CM, Samir P, Galassie A, Boone B. Targeted Identification of Protein Interactions in Eukaryotic mRNA Translation. Proteomics 2020; 20:e1900177. [PMID: 32027465 DOI: 10.1002/pmic.201900177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 12/13/2019] [Indexed: 11/09/2022]
Abstract
To identify protein-protein interactions and phosphorylated amino acid sites in eukaryotic mRNA translation, replicate TAP-MudPIT and control experiments are performed targeting Saccharomyces cerevisiae genes previously implicated in eukaryotic mRNA translation by their genetic and/or functional roles in translation initiation, elongation, termination, or interactions with ribosomal complexes. Replicate tandem affinity purifications of each targeted yeast TAP-tagged mRNA translation protein coupled with multidimensional liquid chromatography and tandem mass spectrometry analysis are used to identify and quantify copurifying proteins. To improve sensitivity and minimize spurious, nonspecific interactions, a novel cross-validation approach is employed to identify the most statistically significant protein-protein interactions. Using experimental and computational strategies discussed herein, the previously described protein composition of the canonical eukaryotic mRNA translation initiation, elongation, and termination complexes is calculated. In addition, statistically significant unpublished protein interactions and phosphorylation sites for S. cerevisiae's mRNA translation proteins and complexes are identified.
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Affiliation(s)
- Andrew J Link
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.,Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA.,Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Xinnan Niu
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Connie M Weaver
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Jennifer L Jennings
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Dexter T Duncan
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - K Jill McAfee
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Morgan Sammons
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, 37232, USA
| | - Vince R Gerbasi
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Adam R Farley
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Tracey C Fleischer
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | | | - Parimal Samir
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Allison Galassie
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Braden Boone
- Department of Bioinformatics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
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Saade GR, Boggess KA, Sullivan SA, Markenson GR, Iams JD, Coonrod DV, Pereira LM, Esplin MS, Cousins LM, Lam GK, Hoffman MK, Fox AC, Lueth AJ, Hsu C, Dykes A, Dufford MT, Polpitiya AD, Kearney PE, Randolph TL, Boniface JJ, Hickok DE, Fleischer TC. 356: PPROM and PTL phenotypes are characterized by differences in underlying biochemical pathways. Am J Obstet Gynecol 2017. [DOI: 10.1016/j.ajog.2016.11.614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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10
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Boggess K, Saade GR, Sullivan SA, Markenson GR, Iams JD, Coonrod DV, Pereira LM, Esplin MS, Cousins LM, Lam GK, Hoffman MK, Fox AC, Lueth AJ, Hsu C, Dufford MT, Fleischer TC, Polpitiya AD, Kearney PE, Hickok DE, Boniface JJ, Randolph TL. 337: Use of a second trimester serum-based proteomic risk classifier for prediction of spontaneous and medically-indicated preterm birth. Am J Obstet Gynecol 2017. [DOI: 10.1016/j.ajog.2016.11.595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Bradford C, Severinsen R, Pugmire T, Rasmussen M, Stoddard K, Uemura Y, Wheelwright S, Mentinova M, Chelsky D, Hunsucker SW, Kearney P, Hickok D, Fleischer TC, Ichetovkin I, Boniface JJ, Critchfield GC, Peltier JM. Analytical validation of protein biomarkers for risk of spontaneous preterm birth. Clinical Mass Spectrometry 2017. [DOI: 10.1016/j.clinms.2017.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
Five compounds were isolated altogether from the two medicinal plants. Glycerol monotricosanoate (1), palmarumycin BG1 (2) and de-O-methyllasiodiplodin (3) were isolated from Gouania longipetala. In addition, epicatechin (4) and its dimer procyanidin B2 (5) were isolated from the stem bark of Glyphaea brevis. Their structures were elucidated by using spectroscopic experiments. They exhibited radical scavenging and moderate antibacterial effects.
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Affiliation(s)
- E Ekuadzi
- a Department of Pharmacognosy , Kwame Nkrumah University of Science and Technology , Kumasi , Ghana
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Baichwal VR, Willardsen AJ, Lockman JW, Murphy BJ, Gordillo R, Fleischer TC, Bradford CL, Papac DI, Mather GG, Carlson RO. Abstract LB-393: The cancer metabolism inhibitor MPC-9528 induces tumor regression in xenograft models with multiple dosing schedules by causing rapid and sustained reduction in tumor NAD. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-lb-393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Introduction: MPC-9528 is a potent, selective, orally bioavailable inhibitor of nicotinamide phosphoribosyltransferase (Nampt), which catalyzes the rate-limiting step for NAD biosynthesis from nicotinamide. Inhibition of Nampt by MPC-9528 results in cell death as a consequence of NAD depletion and inhibition of ATP synthesis. MPC-9528 is a potent tumoricidal agent of cancer cell lines of diverse origin and shows anti-tumor activity in multiple xenograft models. Here we explore the determinants of efficacy in xenograft models by comparing the effects of MPC-9528 oral dosing schedules in terms of both tumor NAD depletion and survival.
Methods: HT1080 human fibrosarcoma cells were implanted subcutaneously into athymic mice (nu/nu) for tumor studies. Dosing was initiated when median tumor volume was >100 mm3. MPC-9528 was dosed orally, either once weekly, once daily, or twice daily, for a total of two or three weeks. For pharmacodynamic (PD) studies, animals were dosed with MPC-9528 and tumors were collected at various times post-dosing for NAD determination by LC-MS/MS.
Results: MPC-9528 (75 mg/kg) dosed once weekly for three weeks in a HT1080 xenograft model resulted in 75% tumor regression on study Day 23, 8 days after the last dose. The ED50 for anti-tumor activity with this schedule was 44 mg/kg and doses at or below 35 mg/kg showed no anti-tumor activity. All doses were equally well-tolerated with <10% change in median body weight. In the same model, MPC-9528 dosed once daily at 10 mg/kg or twice daily at 3 mg/kg for 14 days showed 91% and 92% tumor regression, respectively, by the end of dosing on study Day 15. Two animals in each of the MPC-9528 dose groups showed complete tumor regression. MPC-9528 (4 mg/kg) dosed twice daily resulted in complete tumor regression in 9 out of 10 animals. The plasma concentration versus time profiles of MPC-9528 dosed at 3, 10 or 75 mg/kg indicated that anti-tumor activity was not dependent on maximal concentration of the compound in blood or the total absorbed dose but rather on maintenance of compound concentration above a threshold efficacious concentration. PD studies revealed a rapid and sustained reduction of NAD in tumors from mice dosed with MPC-9528 and that the magnitude and kinetics of NAD change depended on the dose and schedule.
Conclusions: MPC-9528 administration results in regression of tumors when plasma concentrations of compound are maintained above a threshold. MPC-9528 shows comparable efficacy when given intermittently, on a weekly schedule, or continuously on a once, or twice daily schedule. This unique attribute of MPC-9528 reflects its mechanism of action as a cell metabolism inhibitor that functions by inhibiting NAD synthesis in tumor cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-393. doi:10.1158/1538-7445.AM2011-LB-393
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Boniface JJ, Baichwal VR, Cimbora DM, DeMie L, Fleischer TC, Gassman AD, Ghaffari S, Green JP, Flick JS, Terry-Lorenzo RT, Papac DI, Peterson A, Robinson R, Carlson RO. Abstract 577: Basal NAD levels and Nampt expression correlate with in vitro and in vivo sensitivity of tumor cell lines to the Nampt inhibitor MPC-9528. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: MPC-9528 is a potent and selective inhibitor of the NAD biosynthetic enzyme nicotinamide phosphoribosyltransferase (Nampt). Inhibition of Nampt by MPC-9528 causes depletion of cellular NAD followed by a decrease in ATP and cell death. Cancer cells develop dependence on Nampt due to increased metabolic demands and the elevated activity of enzymes such as poly(ADP-ribose) polymerases (Parps) that consume NAD. MPC-9528 has shown anti-tumor activity, ranging from no response to complete regression in a variety of xenograft models.
Materials and Methods: In vitro Nampt activity and cellular NAD levels were measured in coupled biochemical reactions. Cellular Parp activity was measured by immunofluorescent detection of poly(ADP-ribose) (PAR). Enzyme protein and mRNA levels were quantified by western blot and qRT-PCR, respectively. Mechanism of cell death was determined by Caspase 3/7 activity, Caspase 3 and Parp1 cleavage, and SytoxGreen staining. Cell viability was based on ATP levels. Xenografts were performed in nu/nu mice.
Results: MPC-9528 inhibited Nampt activity in vitro with an average IC50 of 40 pM and suppressed cellular NAD levels and nuclear PAR levels, with potencies of 170 pM and 120 pM, respectively. In a screen of 93 cancer cell lines of diverse origin, MPC-9528 had a median TC50 of 2.8 nM with a range of 100 pM to 62 nM. Similar to cultured cells, a range of tumor responses was observed in six different xenograft models. In HCT116 colon carcinoma and HT1080 fibrosarcoma xenografts, oral administration of MPC-9528 at 75 mg/kg intermittently resulted in tumor regressions. In contrast, similar treatment of MIA PaCa-2 pancreatic cancer, N87 gastric carcinoma or HCC827 and NCI-H460 lung cancer xenografts led to partial tumor growth inhibition or no response. The effects in xenografts correlated with TC50 values for MPC-9528 for these cell lines in culture, which ranged from 260 pM to 24 nM. The TC50 values also correlated well with basal cellular NAD levels, IC50 values for MPC-9528-induced NAD depletion, and Nampt protein expression, but not with expression of three other enzymes involved in NAD metabolism – Naprt, Qprt or Parp1. The mechanism of cell death induced by MPC-9528 was cell type dependent and did not correlate with MPC-9528 potency in culture.
Conclusions: NAD levels in cancer cell lines are primarily dependent upon the Nampt pathway. The differential sensitivity of tumor cells to the Nampt inhibitor MPC-9528 is likely due to the magnitude of NAD production, which is a function of Nampt expression. MPC-9528 has the greatest effect on tumor cell lines with lower Nampt expression; therefore, a companion diagnostic based upon Nampt expression in primary tumor specimens could be used to select patients most likely to respond to MPC-9528 monotherapy in the clinic.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 577. doi:10.1158/1538-7445.AM2011-577
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Terry-Lorenzo RT, Douce TB, Austin HA, Boniface JJ, Cimbora DM, Fleischer TC, Carlson RO. Abstract 2551: The Nampt inhibitor MPC-9528 synergizes with DNA damaging agents. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-2551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: MPC-9528 reduces cellular NAD levels and causes cell death, by blocking the NAD salvage pathway through inhibition of nicotinamide phosphoribosyltransferase (Nampt). Many DNA damaging agents also reduce cellular NAD levels, by activating the NAD consuming enzyme poly(ADP-ribose) polymerase (Parp). We hypothesized that the combination of a Nampt inhibitor and a DNA damaging agent would synergize in killing cancer cells, due to a combined effect on NAD levels through two independent mechanisms.
Methods: Cellular NAD was measured using a coupled enzymatic assay. Drug combination experiments were performed in HCT116 colon carcinoma cells, using measurement of ATP levels as a cell viability endpoint. Synergy, antagonism, or additivity was assessed using the MacSynergy II program.
Results: In HCT116 cells, saturating doses of MPC-9528 induced depletion of NAD with a half-life of 5 hours and a decrease in ATP that was delayed approximately 14 hours relative to NAD. Lower, sublethal concentrations of MPC-9528 induced partial NAD depletion without a concomitant ATP loss. At these sublethal concentrations, MPC-9528 was found to synergize with the DNA alkylating agents temozolomide and streptozotocin, which are known to activate Parp. Additionally, MPC-9528 was found to synergize with two structurally different thymidylate synthase inhibitors, 5-fluorouracil (5-FU) and raltitrexed, neither of which have been reported to activate Parp. Individually, 5-FU and raltitrexed each caused NAD depletion in HCT116 cells, which was enhanced by combination with MPC-9528. Furthermore, both 5-FU- and raltitrexed-mediated NAD depletion and synergy with MPC-9528 were completely blocked by the Parp inhibitor olaparib.
Conclusions: Parp activation induced by the alkylating agents temozolomide and streptozotocin, or by the thymidylate synthase inhibitors 5-FU and raltitrexed, is the basis for tumoricidal synergy with the Nampt inhibitor MPC-9528. This synergy is a direct consequence of the NAD depletion resulting from Parp activation coupled with the inhibition of NAD synthesis due to Nampt inhibition. These results provide a basis for clinical combination of MPC-9528 with the agents studied here or with related agents that induce Parp activation.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2551. doi:10.1158/1538-7445.AM2011-2551
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Mensah AY, Donkor PO, Fleischer TC. Anti-inflammatory and antioxidant activities of the leaves of Wissadula amplissima var Rostrata. Afr J Tradit Complement Altern Med 2010; 8:185-95. [PMID: 22238501 PMCID: PMC3252697 DOI: 10.4314/ajtcam.v8i2.63207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The present study determined the anti-inflammatory activity of Wissadula amplissima var rostrata (Schum. & Thonn.), and calculated the total phenolic content and total antioxidant capacity of the plant in an attempt to justify the traditional uses of the plant in the Ashanti region of Ghana for the management of spider,wasps and bee stings. Powdered dried leaves of Wissadula amplissima were Soxhlet extracted with Petroleum Ether (PWA, yield: 1.46% (w)/(w)); Chloroform (CWA, yield: 1.18% (w)/(w)) and Methanol (MWA, yield: 3.39% (w)/(w)). These fractions were tested for anti-inflammatory activity using carrageenan-induced foot edema in 7 day old chicks. The effect before the induction of inflammation (pre-emptive protocol) paradigm was used for the assessment. Oral administration of PWA, CWA and MWA (30 - 300 mg/kg) dose dependently reduced edema with maximal effects of 68.25±2.03%, 77.83±0.81% and 62.21±2.61% respectively. Similarly the NSAID, Diclofenac (10 - 100 mg/Kg, i.p) and the steroidal anti-inflammatory drug dexamethasone (0.3 - 3 mg/Kg, i.p) used as positive controls, dose-dependently inhibited the edema with maximal effect of 87.96±1.11% and 67.47±3.51% respectively. The potencies exhibited by all three extracts were comparable to that shown by Diclofenac but higher than that of Dexamethasone. Phenols were detected in all three extracts with the highest concentration in the MWA. The extracts also scavenged DPPH with EC(50) values of 0.9784, 0.9096 and 0.2767 for PWA, CWA, MWA respectively. The results of this study give scientific credence to the local use of Wissadula amplissima to modulate inflammation induced by stings of animals.
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Affiliation(s)
- A Y Mensah
- Department of Pharmacognosy, Faculty of Pharmacy & Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
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Lockman JW, Murphy BR, Zigar DF, Judd WR, Slattum PM, Gao ZH, Ostanin K, Green J, McKinnon R, Terry-Lorenzo RT, Fleischer TC, Boniface JJ, Shenderovich M, Willardsen JA. Analogues of 4-[(7-Bromo-2-methyl-4-oxo-3H-quinazolin-6-yl)methylprop-2-ynylamino]-N-(3-pyridylmethyl)benzamide (CB-30865) as potent inhibitors of nicotinamide phosphoribosyltransferase (Nampt). J Med Chem 2010; 53:8734-46. [PMID: 21080724 DOI: 10.1021/jm101145b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have shown previously that the target of the potent cytotoxic agent 4-[(7-bromo-2-methyl-4-oxo-3H-quinazolin-6-yl)methyl-prop-2-ynylamino]-N-(3-pyridylmethyl)benzamide (CB38065, 1) is nicotinamide phosphoribosyltransferase (Nampt). With its cellular target known we sought to optimize the biochemical and cellular Nampt activity of 1 as well as its cytotoxicity. It was found that a 3-pyridylmethylamide substituent in the A region was critical to cellular Nampt activity and cytotoxicity, although other aromatic substitution did yield compounds with submicromolar enzymatic inhibition. Small unsaturated groups worked best in the D-region of the molecule, with 3,3-dimethylallyl providing optimal potency. The E region required a quinazolin-4-one or 1,2,3-benzotriazin-4-one group for activity, and many substituents were tolerated at C² of the quinazolin-4-one. The best compounds showed subnanomolar inhibition of Nampt and low nanomolar cytotoxicity in cellular assays.
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Affiliation(s)
- Jeffrey W Lockman
- Department of Medicinal Chemistry, Myrexis, Inc., Salt Lake City, Utah 84108, USA.
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Fleischer TC, Murphy BR, Flick JS, Terry-Lorenzo RT, Gao ZH, Davis T, McKinnon R, Ostanin K, Willardsen JA, Boniface JJ. Chemical proteomics identifies Nampt as the target of CB30865, an orphan cytotoxic compound. ACTA ACUST UNITED AC 2010; 17:659-64. [PMID: 20609415 DOI: 10.1016/j.chembiol.2010.05.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 05/05/2010] [Accepted: 05/07/2010] [Indexed: 10/19/2022]
Abstract
Drug discovery based on cellular phenotypes is impeded by the challenge of identifying the molecular target. To alleviate this problem, we developed a chemical proteomic process to identify cellular proteins that bind to small molecules. CB30865 is a potent (subnanomolar) and selective cytotoxic compound of previously unknown mechanism of action. By combining chemical proteomics with biochemical and cellular pharmacology we have determined that CB30865 cytotoxicity is due to subnanomolar inhibition of nicotinamide phosphoribosyltransferase (Nampt), an enzyme present in the NAD biosynthetic pathway. Cancer cells develop dependence on Nampt due to increased energy requirements and the elevated activity of NAD consuming enzymes such as sirtuins and mono and poly(ADP-ribose) polymerases (PARPs). These findings suggest new chemical starting points for Nampt inhibitors and further implicate this enzyme as a target in cancer.
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Affiliation(s)
- Tracey C Fleischer
- Department of Discovery Biology, Myriad Pharmaceuticals, Salt Lake City, UT 84108, USA
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Fleischer TC, Flick JS, Terry-Lorenzo RT, Gao ZH, Murphy BR, Willardson JA, Boniface JJ. Abstract 3673: Identifying the target of an orphan compound: CB30865 is a Nampt inhibitor. Cancer Res 2010. [DOI: 10.1158/1538-7445.am10-3673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: Drug discovery based on cellular phenotypes is impeded by the challenge of identifying the molecular target. To alleviate this problem, Myriad Pharmaceuticals has developed a chemical proteomics process to identify cellular proteins that bind to small molecules. CB30865 is a potent and selective cytotoxic compound of previously unknown mechanism of action (1). Using our technology, we have unequivocally demonstrated that CB30865 cytotoxicity is due to inhibition of nicotinamide phosphoribosyltransferase (Nampt). Nampt catalyzes the first step in the synthesis of NAD from nicotinamide. Cancer cells develop dependence on Nampt due to increased energy requirements and the elevated activity of NAD consuming enzymes such as sirtuins and mono and poly(ADP-ribose) polymerases.
Materials and Methods: Direct target affinity purification (DTAP) was performed using analogs of CB30865 (MPI-0479883, MPI-0482594) coupled to beads. Purified proteins were identified by nano-flow reversed-phase liquid chromatography and tandem mass spectrometry using an LTQ-Orbitrap. In vitro Nampt activity was measured in a coupled biochemical assay based on the production of fluorescent resorufin. Nampt cellular activity was assayed by measuring levels of NAD and NAD-dependent polyADP-ribosylation.
Results: As reported (1), 3-pyridyl, but not 2-pyridyl, analogs of CB30865 were potently cytotoxic. A 55 kD protein was purified efficiently using DTAP with MPI-0479883 (a 3-pyridyl CB30856 analog) but not MPI-0482594 (a 2-pyridyl analog). Preincubation of cellular lysates with uncoupled 3-pyridyl but not 2-pyridyl analogs potently blocked binding of the 55 kD protein. Based on LC-MS/MS analyses, the 55 kD protein was identified as Nampt. Immunoblotting of DTAPs using a Nampt specific antibody confirmed the MS identification. Furthermore, biochemical and cellular assays of Nampt activity demonstrated pyridyl-isomer specific enzyme inhibition. Finally, cellular Nampt inhibition and cytotoxicity were completely rescued by treating cells with 10 µM nicotinic acid as an alternate NAD source.
Conclusions: The chemical proteomics DTAP approach is a powerful tool to identify molecular targets of orphan compounds. We demonstrate this here through identification of Nampt as the molecular target of CB30865 and further implicate NAD metabolism as a functional target for cancer.
(1) Skelton LA, Ormerod MG, Titley J, Kimbell R, Brunton LA, Jackman AL. A novel class of lipophilic quinazoline-based folic acid analogues: cytotoxic agents with a folate-independent locus. Br J Cancer. 1999 Apr;79(11-12):1692-701.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3673.
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Fleischer TC, Mensah MLK, Mensah AY, Komlaga G, Gbedema SY, Skaltsa H. Antimicrobial activity of essential oils of Xylopia aethiopica. Afr J Tradit Complement Altern Med 2008; 5:391-3. [PMID: 20161962 DOI: 10.4314/ajtcam.v5i4.31295] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Xylopia aethiopica is a medicinal plant of great repute in West Africa which produces a variety of complex chemical compounds. The fresh and dried fruits, leaf, stem bark and root bark essential oils showed various degrees of activity against the gram positive bacteria, Bacillus subtilis and Staphylococcus aureus, the gram negative bacteria Pseudomonas aeruginosa and the yeast-like fungus Candida albicans, using the cup plate method. However, none of the oils showed activity against Escherichia coli.
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Affiliation(s)
- T C Fleischer
- Faculty of Pharmacy and Pharmaceutical Sciences, Department of Herbal Medicine, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. fleischer@yahoo com
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Fleischer TC, Weaver CM, McAfee KJ, Jennings JL, Link AJ. Systematic identification and functional screens of uncharacterized proteins associated with eukaryotic ribosomal complexes. Genes Dev 2006; 20:1294-307. [PMID: 16702403 PMCID: PMC1472904 DOI: 10.1101/gad.1422006] [Citation(s) in RCA: 221] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Accepted: 03/15/2006] [Indexed: 11/24/2022]
Abstract
Translation regulation is a critical means by which cells control growth, division, and apoptosis. To gain further insight into translation and related processes, we performed multifaceted mass spectrometry-based proteomic screens of yeast ribosomal complexes and discovered an association of 77 uncharacterized yeast proteins with ribosomes. Immunoblotting revealed an EDTA-dependent cosedimentation with ribosomes in sucrose gradients for 11 candidate translation-machinery-associated (TMA) proteins. Tandem affinity purification linked one candidate, LSM12, to the RNA processing proteins PBP1 and PBP4. A second candidate, TMA46, interacted with RBG1, a GTPase that interacts with ribosomes. By adapting translation assays to high-throughput screening methods, we showed that null yeast strains harboring deletions for several of the TMA genes had alterations in protein synthesis rates (TMA7 and TMA19), susceptibility to drugs that inhibit translation (TMA7), translation fidelity (TMA20), and polyribosome profiles (TMA7, TMA19, and TMA20). TMA20 has significant sequence homology with the oncogene MCT-1. Expression of human MCT-1 in the Deltatma20 yeast mutant complemented translation-related defects, strongly implying that MCT-1 functions in translation-related processes. Together these findings implicate the TMA proteins and, potentially, their human homologs, in translation related processes.
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Affiliation(s)
- Tracey C Fleischer
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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Mensah AY, Houghton PJ, Dickson RA, Fleischer TC, Heinrich M, Bremner P. In Vitro evaluation of effects of two ghanaian plants relevant to wound healing. Phytother Res 2006; 20:941-4. [PMID: 16909445 DOI: 10.1002/ptr.1978] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Commelina diffusa and Spathodea campanulata are used as wound-healing agents in Ashanti traditional medicine in Ghana. The methanol extracts of Commelina diffusa herb and Spathodea campanulata bark showed some level of antimicrobial activity with C. diffusa exhibiting selective antifungal activity against Trichophyton species. The extracts reduced the peroxidation of bovine brain extract with an IC(50) value of 1.39 mg/mL and 0.24 mg/mL, respectively. In addition the extracts also exhibited significant antioxidant activity by protecting MRC-5 cells from hydrogen peroxide induced oxidant injury at concentrations between 1 microg/mL and 10 microg/mL. The extracts showed no inhibition of NF-kappaB at 100 microg/mL. The antioxidant activities and antimicrobial activities suggest that the use of the plants in wound healing may be based on antioxidant and antiseptic effects of its constituents.
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Affiliation(s)
- Abraham Y Mensah
- Department of Pharmacognosy, Faculty of Pharmacy, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana
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Link AJ, Fleischer TC, Weaver CM, Gerbasi VR, Jennings JL. Purifying protein complexes for mass spectrometry: applications to protein translation. Methods 2005; 35:274-90. [PMID: 15722224 DOI: 10.1016/j.ymeth.2004.08.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Accepted: 08/25/2004] [Indexed: 10/25/2022] Open
Abstract
Proteins control and mediate most of the biological activities in the cell. In most cases, proteins either interact with regulatory proteins or function in large molecular assemblies to carryout biological processes. Understanding the functions of individual proteins requires the identification of these interacting proteins. With its speed and sensitivity, mass spectrometry has become the dominant method for identifying components of protein complexes. This article reviews and discusses various approaches to purify protein complexes and analyze the proteins using mass spectrometry. As examples, methods to isolate and analyze protein complexes responsible for the translation of messenger RNAs into polypeptides are described.
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Affiliation(s)
- Andrew J Link
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-8575, USA.
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Mensah AY, Houghton PJ, Akyirem GNA, Fleischer TC, Mensah MLK, Sarpong K, Adosraku R. Evaluation of the antioxidant and free radical scavenging properties ofSecamone afzelii Rhoem. Phytother Res 2005; 18:1031-2. [PMID: 15742341 DOI: 10.1002/ptr.1614] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The antioxidant activity of a methanol extract of Secamone afzelii stems was tested using the DPPH assay and the active compound was identified as alpha-tocopherol. HPLC determination showed that 0.12% w/w alpha-tocopherol was present in the plant. The total extract also showed effective free radical scavenging activity in the assay for non-enzymatic lipid peroxidation in liposomes with an IC50 value of 90 microg/mL, with alpha-tocopherol isolated from the plant having an IC50 of 15 microg/mL in the same system, thus demonstrating the presence of other antioxidants.
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Affiliation(s)
- A Y Mensah
- Department of Pharmacognosy, Faculty of Pharmacy, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
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Lewis PW, Beall EL, Fleischer TC, Georlette D, Link AJ, Botchan MR. Identification of a Drosophila Myb-E2F2/RBF transcriptional repressor complex. Genes Dev 2004; 18:2929-40. [PMID: 15545624 PMCID: PMC534653 DOI: 10.1101/gad.1255204] [Citation(s) in RCA: 215] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Drosophila Myb complex has roles in both activating and repressing developmentally regulated DNA replication. To further understand biochemically the functions of the Myb complex, we fractionated Drosophila embryo extracts relying upon affinity chromatography. We found that E2F2, DP, RBF1, RBF2, and the Drosophila homolog of LIN-52, a class B synthetic multivulva (synMuv) protein, copurify with the Myb complex components to form the Myb-MuvB complex. In addition, we found that the transcriptional repressor protein, lethal (3) malignant brain tumor protein, L(3)MBT, and the histone deacetylase, Rpd3, associated with the Myb-MuvB complex. Members of the Myb-MuvB complex were localized to promoters and were shown to corepress transcription of developmentally regulated genes. These and other data now link together the Myb and E2F2 complexes in higher-order assembly to specific chromosomal sites for the regulation of transcription.
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Affiliation(s)
- Peter W Lewis
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3204, USA
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Abstract
The mSin3A corepressor complex contains 7 to 10 tightly associated polypeptides and is utilized by many transcriptional repressors. Much of the corepressor function of mSin3A derives from associations with the histone deacetylases HDAC1 and HDAC2; however, the contributions of the other mSin3A-associated polypeptides remain largely unknown. We have purified an mSin3A complex from K562 erythroleukemia cells and identified three new mSin3A-associated proteins (SAP): SAP180, SAP130, and SAP45. SAP180 is 40% identical to a previously identified mSin3A-associated protein, RBP1. SAP45 is identical to mSDS3, the human ortholog of the SDS3p component of the Saccharomyces cerevisiae Sin3p-Rpd3p corepressor complex. SAP130 does not have detectable homology to other proteins. Coimmunoprecipitation and gel filtration data suggest that the new SAPs are, at the very least, components of the same mSin3A complex. Each new SAP repressed transcription when tethered to DNA. Furthermore, repression correlated with mSin3A binding, suggesting that the new SAPs are components of functional mSin3A corepressor complexes. SAP180 has two repression domains: a C-terminal domain, which interacts with the mSin3A-HDAC complex, and an N-terminal domain, which functions independently of mSin3A-HDAC. SAP130 has a repression domain at its C terminus that interacts with the mSin3A-HDAC complex and an N-terminal domain that probably mediates an interaction with a transcriptional activator. Together, our data suggest that these novel SAPs function in the assembly and/or enzymatic activity of the mSin3A complex or in mediating interactions between the mSin3A complex and other regulatory complexes. Finally, all three SAPs bind to the HDAC-interaction domain (HID) of mSin3A, suggesting that the HID functions as the assembly interface for the mSin3A corepressor complex.
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Affiliation(s)
- Tracey C Fleischer
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT 84112-5555, USA
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Abstract
The ethanolic extracts of the leaves and flowering tops of Acanthospermum hispidum showed varying degrees of activity against a wide range of pathogenic bacteria. The activity resided mostly in the polar fractions of the alcoholic extract, being only slight in the non-polar fractions. No activity was observed for the aqueous extract of the fresh plant material.
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Affiliation(s)
- T C Fleischer
- Department of Pharmacognosy, Faculty of Pharmacy, K.N.U.S.T., Kumasi, Ghana.
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Abstract
The ethanolic extracts of the leaves and seeds of Bixa orellana showed a broad spectrum of antimicrobial activity. The activity of the leaf extract was more pronounced.
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Affiliation(s)
- T C Fleischer
- Department of Pharmacognosy, Faculty of Pharmacy, K.N.U.S.T., Kumasi, Ghana.
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Hassig CA, Tong JK, Fleischer TC, Owa T, Grable PG, Ayer DE, Schreiber SL. A role for histone deacetylase activity in HDAC1-mediated transcriptional repression. Proc Natl Acad Sci U S A 1998; 95:3519-24. [PMID: 9520398 PMCID: PMC19868 DOI: 10.1073/pnas.95.7.3519] [Citation(s) in RCA: 296] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Treatment of mammalian cells with small molecule histone deacetylase (HDAC) inhibitors induces changes in the transcription of specific genes. These changes correlate directly with an increase in the acetylation levels of all four core histones in vivo. Antibodies directed against endogenous HDAC1, HDAC2, or HDAC3 immunoprecipitate histone deacetylase activity that is inhibited in vitro by the small molecule trapoxin (TPX), and all three HDACs are retained by a TPX-affinity matrix. HDAC1 and HDAC2 are associated in HeLa cells in a complex that is predominantly separate from an HDAC3 immune complex. Both Jurkat HDAC1 and HeLa HDAC1/2 immune complexes deacetylate all four core histones and recombinant HDAC1 deacetylates free and nucleosomal histones in vitro. Purified recombinant HDAC1 deacetylates core histones in the absence of protein cofactors. Site-directed mutagenesis was used to identify residues required for the enzymatic and structural integrity of HDAC1. Mutation of any one of four conserved residues causes deleterious effects on deacetylase activity and a reduced ability to bind a TPX-affinity matrix. A subset of these mutations also cause a decreased interaction with the HDAC1-associated proteins RbAp48 and mSin3A. Disruption of histone deacetylase activity either by TPX or by direct mutation of a histidine presumed to be in the active site abrogates HDAC1-mediated transcriptional repression of a targeted reporter gene in vivo.
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Affiliation(s)
- C A Hassig
- Howard Hughes Medical Institute, Department of Chemistry, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
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31
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Abstract
Members of the Mad family of bHLH-Zip proteins heterodimerize with Max to repress transcription in a sequence-specific manner. Transcriptional repression by Mad:Max heterodimers is mediated by ternary complex formation with either of the corepressors mSin3A or mSin3B. We report here that mSin3A is an in vivo component of large, heterogeneous multiprotein complexes and is tightly and specifically associated with at least seven polypeptides. Two of the mSin3A-associated proteins, p50 and p55, are highly related to the histone deacetylase HDAC1. The mSin3A immunocomplexes possess histone deacetylase activity that is sensitive to the specific deacetylase inhibitor trapoxin. mSin3A-targeted repression of a reporter gene is reduced by trapoxin treatment, suggesting that histone deacetylation mediates transcriptional repression through Mad-Max-mSin3A multimeric complexes.
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Affiliation(s)
- C A Hassig
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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