Last Updated: 4/12/2010

Research Interests
My research is focused on mechanisms of DNA replication, DNA repair, and DNA damage activation of cell cycle checkpoints in human cells. Inherited and acquired defects in the molecular network of protection of genetic stability are associated with increased risk for mutations underlying cancer pathogenesis. My laboratory studies how human cells succeed in completing genome duplication, even in the presence of DNA lesions that block the replication machinery. DNA damage tolerance depends on the replication fork protection complex avoiding the collapse of stalled forks and mechanisms to replicate past the template lesion. Our studies have been focused primarily on the response of human cells to DNA damage caused by ultraviolet (UV) radiation. Current efforts are directed toward the identification of key molecular events that contribute to the development of skin cancers in areas exposed to sunlight. The component of solar radiation that is most damaging to the skin is represented by the wavelengths of UV that penetrate the Earth atmosphere (UVB and UVA). Therefore, it is our goal to translate past research experience with biological effects of UVC in cultured fibroblasts to clinically relevant cell types. In this regard, my laboratory is collaborating with a group of basic scientists and clinical investigators with expertise in different aspects of DNA repair, replication, and checkpoint control in UV-exposed human cells, as well as the epidemiology and pathogenesis of malignant melanoma. Such a multidisciplinary effort is needed for reaching a better understanding of how several DNA metabolic pathways and cellular responses to DNA damage are coordinated in the target cell for skin melanomas (melanocytes) or carcinomas (keratinocytes) and how these protective barriers might be compromised during cancer development.

Recent Accomplishments and Honors
My laboratory used XP-V cells to investigate the underlying defect responsible for their enhanced sensitivity to UV-induced mutagenesis and to search for the identity of the XP-V gene product. Cell biology studies and development of biochemical assays with specificity and sensitivity to detect translesion synthesis (TLS) of a single cyclobutane pyrimidine dimer (CPD) in double stranded DNA helped to build the foundation for the discovery of DNA polymerase eta by other laboratories. This specialized polymerase catalyses accurate TLS of pyrimidine dimers and its absence in XP-V accounts for their UV hypermutability. Our initial studies were expanded to include analyses of the structure of DNA replication intermediates, the evaluation of translesion synthesis versus template switching as the primary mode of replication past thymine dimers in vitro, and the effect of the position of the DNA lesion (either on the template for the leading or the lagging strand of nascent DNA) on the efficiency of bypass of DNA photoproducts. The same system was later adapted to demonstrate that K164-PCNA ubiquitylation is not essential for pol eta-dependent translesion synthesis in vitro.

Complementation of expression of wild-type pol eta in XP-V cells generated isogenic pairs of diploid human fibroblasts for studies of the biological role(s) of this specialized polymerase in DNA damage tolerance, following exposure to either physical or chemical carcinogens. These isogenic cells represent valuable tools for studies of intracellular mechanisms of recruitment of pol eta to replication forks stalled at a CPD and, after lesion bypass, keeping this polymerase from replicating undamaged DNA, since pol eta has significantly lower fidelity than the normal replicative DNA polymerases. A study in collaboration with the Chaney laboratory indicated that pol eta is also involved in accurate translesion synthesis of certain DNA adducts formed by cisplatin, a drug commonly used in cancer chemotherapy.

Current studies are comparing the capacity for replication of the UV-damaged DNA and for activation of the intra-S checkpoint in a group of melanoma cell lines that carry BRAF or NRAS mutations, or are wild type at these two loci. Results to date show no correlation between these genotypes and how close (normal) or far (abnormal) the responses to UV of S phase melanoma cells are to those previously characterized in diploid NHF (studies with primary melanocytes are underway). Important aspects of these studies are (i) the inclusion of molecular dosimetry of UV-induced photoproducts for proper comparison of the dose received by each cell line (instead of the incident fluence), and (ii) the comparison of biological responses to UVC, UVB or UVA to evaluate whether DNA photoproducts alone can explain their effects on S phase cells, or other types of cellular damage becomes a significant component of the measured endpoints.

DNA damage checkpoints cooperate with nucleotide excision repair to minimize the risk associated with replicating DNA containing lesions by inhibiting entry of cells into the S phase of the cell cycle or delaying initiation at banks of replicons not yet activated. My laboratory has been particularly interested in the signaling pathways that underlie the intra-S phase checkpoint responses of inhibition of replicon initiation and rate of replication fork displacement in human cells exposed to UV. Investigations into the biology and biochemistry of these pathways benefited from the development of new technologies and close collaborations with other Cancer Center investigators, in particularly the laboratories of David G. Kaufman, William K. Kaufmann, and Aziz Sancar.

Training
B.S. (1969), M.S. (1972, and Ph.D. (1976) - University of Sao Paulo, Brazil

Pre-doctoral research at the University of Texas at Austin (1972-1975)

Post-doctoral research at the University of North Carolina at Chapel Hill

Publications
Bower JJ, Zhou Y, Zhou T, Simpson DA, Arlander SJ, Paules RS, Cordeiro-Stone M, Kaufmann WK: Revised genetic requirements for the decatenation G2 checkpoint: The role of ATM. Cell Cycle. 2010 Apr 10;9(8). [Epub ahead of print].

Kemp MG, Akan Z, Yilmaz S, Grillo M, Smith-Roe SL, Kang T-H, Cordeiro-Stone M, Kaufmann WK, Abraham, RT, Sancar A., Ünsal-Kaçmaz K: Tipin-RPA interaction mediates Chk1 phosphorylation by ATR in response to genotoxic stress. J Biol Chem. 2010 Mar 15. [Epub ahead of print].

Nevis KR, Cordeiro-Stone M, and Cook JG: Origin licensing and p53 status regulate Cdk2 activity during G1. Cell Cycle 2009 Jun 15;8(12):1952-1963

Cohen SM, Chastain II PD, Cordeiro-Stone M, Kaufman DG: DNA replication and the GINS complex: localization on extended chromatin fibers. Epigenetics & Chromatin 2009, May 14;2:6.

Nikolaishvili-Feinberg N, Jenkins GS, Nevis KR, Staus DP, Scarlett CO, Ünsal-Kaçmaz K, Kaufmann WK, Cordeiro-Stone M. Ubiquitylation of Proliferating Cell Nuclear Antigen and Recruitment of Human DNA Polymerase eta. Biochemistry. 2008 Apr 1;47(13):4141-50

Kaufmann WK, Nevis K, Qu P-P, Ibrahim I, Zhou T, Zhou Y, Simpson DA, Helms-Deaton J, Cordeiro-Stone M, Moore D, Thomas NE, Hao H, Liu Z, Shields JM, Scott G, Sharpless N: Defective cell cycle checkpoint functions in melanoma are associated with altered patterns of gene expression. J Invest Dermatol. 2008 Jan;128(1):175-87

Cohen SM, Cordeiro-Stone M, Kaufman DG: Early replication and the apoptotic pathway. J Cell Physiol. 2007 Nov;213(2):434-9

Kaufman DG, Cordeiro-Stone M, Brylawski BP, Cohen SM, Chastain PD: Early S phase DNA replication: A search for targets of carcinogenesis. Adv Enzyme Regul. 2007;47:127-38.

Ünsal-Kaçmaz K, Chastain PD, Qu P-P, Minoo P, Cordeiro-Stone M, Sancar A, Kaufmann WK: The human Timeless/Tipin complex coordinates an intra-S checkpoint response to UV that slows replication fork displacement. Mol Cell Biol. 2007 Apr;27(8):3131-42.

Brylawski BP, Chastain PD, Cohen SM, Cordeiro-Stone M, Kaufman DG: Mapping of an origin of replication in the promoter of Fragile X Gene FMR1. Exp Mol Pathology. 2007 Apr;82(2):190-6.

Heffernan TP, Ünsal-Kaçmaz K, Heinlock AN, Simpson DA, Paules RS, Sancar A, Cordeiro-Stone M, Kaufmann WK: Cdc7-Dbf4 and the Human S Checkpoint Response to UVC. J Biol Chem. 2007 Mar 30;282(13):9458-68.

Kaufmann WK, Filatov L, Oglesbee SE, Simpson DA, Lotano MA, McKeen HD, Sawyer LR, Moore DT, Millikan RC, Cordeiro-Stone M, Carey LA: Radiation clastogenesis and cell cycle checkpoint function as functional markers of breast cancer risk. Carcinogenesis. 2006 Dec;27(12):2519-27

Thomas NE, Berwick M, Cordeiro-Stone M: Could BRAF mutations in melanocytic lesions arise from DNA damage induced by ultraviolet radiation? J Invest Dermatol. 2006 Aug;126(8):1693-6

Lima-Bessa KM, Chiganças V, Stary A, Kannouche P, Sarasin A, Armelini MG, Jacysyn JF, Amarante-Mendes GP, Cordeiro-Stone M, Cleaver JE, Menck, CFM: Adenovirus mediated transduction on the human DNA polymerase eta cDNA. DNA Repair (Amst). 2006 Aug 13;5(8):925-34

Chastain II PD, Heffernan TP, Nevis KR, Lin L, Kaufmann WK, Kaufman DG, Cordeiro-Stone M: Checkpoint regulation of replication dynamics in UV-irradiated human cells. Cell Cycle. 2006b Sep;5(18):2160-7

King NM, Nikolaishvili-Feinberg N, Bryant MF, Luche DD, Heffernan TP, Simpson DA, Hanaoka F, Kaufmann WK, Cordeiro-Stone M: Overproduction of DNA polymerase eta does not raise the spontaneous mutation rate in diploid human fibroblasts. DNA Repair (Amst). 2005 Jun 8;4(6):714-24

E-mail: uncmcs@med.unc.edu
Telephone: (919) 966-1396
FAX: (919) 966-5046
Address: 620A Brinkhous-Bullitt Chapel Hill, NC 27599-7525

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