Headshot photo of R. Stephen Lloyd, Ph.D.

R. Stephen Lloyd, Ph.D.

  • Professor, Oregon Institute of Occupational Health Sciences
  • Professor of Molecular and Medical Genetics, School of Medicine
  • Associate Director for Basic Research, Oregon Institute of Occupational Health Sciences
  • Molecular and Medical Genetics Graduate Program, School of Medicine
  • Graduate Program in Biomedical Sciences, School of Medicine
  • Cancer Biology Graduate Program, School of Medicine


Dr. R. Stephen Lloyd received his BS in Biology from Florida State University in 1975, majoring in marine pollution biology. His research interests turned to cancer chemotherapy and in 1979, he earned his Ph.D. in Molecular Biology from the University of Texas Graduate School of Biomedical Sciences in Houston, TX. After learning about mechanisms by which DNA can be damaged, he began his career in DNA repair as a postdoctoral fellow at Stanford University in the laboratory of Dr. Philip Hanawalt. Following two years at Stanford, he worked for two more years for a genetic engineering company, before joining the Biochemistry Department at Vanderbilt University in 1983. In his ten-year stay at Vanderbilt, Dr. Lloyd rose through the ranks to Full Professor, and his research focused on both DNA repair and molecular mutagenesis. He was then recruited to the Center for Molecular Science at the University of Texas Medical Branch in which the faculty exclusively specialized in DNA repair mechanisms. During his twelve years at UTMB, he also became the Director of two Centers in Environmental Toxicology. In August 2003, he, along with his wife, Dr. Amanda K. McCullough was recruited to join the CROET faculty at OHSU. Together they have both separate and joint research projects in the research areas described below.

Education and training

    • B.S., 1975, Florida State University
    • Ph.D., 1979, University of Texas Houston Graduate School of Biomedical Sciences

Memberships and associations:

  • American Association for the Advancement of Science (AAAS)
  • Environmental Mutagenesis & Genomics Society
  • Federation of the American Societies of Experimental Biology

Areas of interest

  • Strategies to prevent sunlight-induced skin cancer via the topical introduction of repair enzymes into human cells
  • The mechanisms by which the loss of a DNA repair enzyme can lead to the clinical manifestations of Metabolic Syndrome - a constellation of diseases (obesity, fatty liver disease, insulin resistance and hypertension) that affect >45 million Americans
  • Mutagenic potential of alkyl-substituted and unsubstituted Fapy-dG adducts
  • Molecular mechanisms for the repair and replication of DNA-protein crosslinks
  • Replication bypass of DNAs containing interstrand DNA crosslinks

Honors and awards

  • Awards: Editor’s Choice Award for Environmental and Molecular Mutagenesis for Sha Y, Minko IG, Malik CK, Rizzo CJ, Lloyd RS. Error-prone replication bypass of the imidazole ring-opened formamidopyrimidine deoxyguanosine adduct. Environ Mol Mutagen. 2017 May;58(4):182-189. PMID:28436537 PMCID: PMC5476229


Selected publications

  • Tomar R, Minko IG, Kellum AH Jr, Voehler MW, Stone MP, McCullough AK, Lloyd RS. DNA Sequence Modulates the Efficiency of NEIL1-Catalyzed Excision of the Aflatoxin B1-Induced Formamidopyrimidine Guanine Adduct. Chem Res Toxicol. 2021 Mar 15;34(3):901-911. PMCID: in progress
  • Owen N, Minko IG, Moellmer SA, Cammann SK, Lloyd RS, McCullough AK. Enhanced cytarabine-induced killing in OGG1-deficient acute myeloid leukemia cells. Proc Natl Acad Sci U S A. 2021 Mar 16;118(11):e2016833118. PMCID: in progress
  • Kant M, Tahara YK, Jaruga P, Coskun E, Lloyd RS, Kool ET, Dizdaroglu M. Inhibition by Tetrahydroquinoline Sulfonamide Derivatives of the Activity of Human 8-Oxoguanine DNA Glycosylase (OGG1) for Several Products of Oxidatively induced DNA Base Lesions.  ACS Chem Biol. 2021 Jan 15;16(1):45-51. PMCID: in progress
  • Paluri SL, Burak M, Senejani AG, Levinson M, Rahim T, Clairmont K, Kashgarian M, Alvarado-Cruz I, Meas R, Cardó-Vila M, Zeiss C, Maher S, Bothwell ALM, Coskun E, Kant M, Jaruga P, Dizdaroglu M, Lloyd RS, Sweasy JB. DNA glycosylase deficiency leads to decreased severity of lupus in the Polb-Y265C mouse model. DNA Repair (Amst). 2021 Jun 24;105:103152. PMCID: in progress
  • Minko IG, Vartanian VL, Tozaki NN, Coskun E, Coskun SH, Jaruga P, Yeo J, David SS, Stone MP, Egli M, Dizdaroglu M, McCullough AK, Lloyd RS. Recognition of DNA adducts by edited and unedited forms of DNA glycosylase NEIL1. DNA Repair (Amst). 2020 Jan;85:102741 PMCID: PMC7069121
  • McCullough, AK, I. G. Minko, IG, A. Nilsen, A, S. Nagarajan, S, and Lloyd, RS (2020) Modulation of DNA Glycosylase Activities via Small Molecules. Chapter 14 in DNA Damage, DNA Repair and Disease, (Eds Miral Dizdaroglu and R. Stephen Lloyd) Royal Society of Chemistry, United Kingdom
  • Sampath, H and Lloyd, RS. Roles of OGG1 in transcriptional regulation and maintenance of metabolic homeostasis. DNA Repair (Amst). 2019 Sep;81:102667 PMCID: PMC6939861.
  • McCullough AK, Lloyd RS. Mechanisms underlying aflatoxin-associated mutagenesis - Implications in carcinogenesis. DNA Repair (Amst). 2019 May;77:76-86 PMCID:PMC6959417
  • Minko IG, Christov PP, Li L, Stone MP, McCullough AK, Lloyd RS. Processing of N5-substituted formamidopyrimidine DNA adducts by DNA glycosylases NEIL1 and NEIL3. DNA Repair (Amst). 2019 Jan;73:49-54 PMCID: PMC6588396
  • Minko IG, Vartanian VL, Tozaki NN, Linde OK, Jaruga P, Coskun SH, Coskun E, Qu C, He H, Xu C, Chen T, Song Q, Jiao Y, Stone MP, Egli M, Dizdaroglu M, McCullough AK, Lloyd RS. Characterization of rare NEIL1 variants found in East Asian populations. DNA Repair (Amst). 2019 May 3;79:32-39 PMCID: PMC6677271 


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