Project 1: Study to determine the cellular response to DNA damage induced by hexavalent chromium.
PI: Paul Chastain, Research Associate, Department of Pathology and Laboratory Medicine, School of Medicine.
PI: Shobhan Gaddameedhi, Ph.D., Post-doctoral Fellow, Department of Biochemistry and Biophysics, School of Medicine.
Project 3: Melanoma: small signal molecules may characterize the disease and guide rational design of therapeutics.
Project: Study to determine the cellular response to DNA damage induced by hexavalent chromium.
Chromium and its compounds have long been used in industry and the by-products of its usage have been proven to pose an environmental health risk. In recent cell survival investigations with DT40 cells knocked out in DNA damage repair as well as cell cycle checkpoint pathways exposed to potassium chromate we have discovered heightened sensitivity to Cr[VI] in cells deficient in the homologous recombination damage repair pathway as well as the cell cycle checkpoint pathway directed by the ATR/ATRIP proteins. These results indicate that both recombination and the ATR/ATRIP pathways are required for cell survival after Cr[VI] exposure. Other preliminary studies we have performed have shown Cr-induced reduction of the rate of replication. In this pilot grant proposal, we seek to determine the mechanism by which the cell controls replication after chromium exposure and the role that homologous recombination may play in that control. Armed with this knowledge, we will be better able to understand how the cell protects itself from chromium-induced DNA damage.
Project: Role of the circadian clock in UV-induced skin carcinogenesis.
Principal Investigator: Shobhan Gaddameedhi, Ph.D., Post-doctoral Fellow, Department of Biochemistry and Biophysics, School of Medicine.
Skin cancer is the most common form of cancer in the United States. Solar ultraviolet radiation (UVR) is a well-known human skin carcinogen. Exposure to the UVR causes DNA damage by generating photoproducts in DNA. In humans, these photoproducts are solely repaired by the process of nucleotide excision repair, and the loss of this repair system is strongly correlated with the development of skin cancer. We recently discovered that the circadian clock regulates nucleotide excision repair in mouse. Our preliminary results suggest that UV-induced DNA repair capacity varies in mouse skin as a function of time of day reaching its maximum in the evening (4 pm) and its minimum in the morning (4 am).The overall goal of this project is to understand how the circadian clock controls cellular responses to UV-induced DNA damage and to determine whether UV exposure at certain times of the day is more likely to cause skin cancer. These studies establish a rational for chrono-photo biology and suggests at what time of the day would be best for sunlight exposure and use of tanning beds.
Project: Melanoma: small signal molecules may characterize the disease and guide rational design of therapeutics.
Several labs have reported (Lu 2005) that TaqMan microRNA (miRNA) assays can reliably discern cancer types and stages. Applied Biosystems technology has enabled exceedingly specific and sensitive, simultaneous RT-qPCR assays of 373 miRNA species in one 384-well plate. After confirming performance reported by others (Chen 2005, Orina 2009), we are now prepared to apply the technology. A notable publication by Jukic et al. (Jukic 2010) described TaqMan results for FFPE samples from melanoma patients, including certain miRNAs dramatically differentiated. Our preliminary tests with RNA isolated from seven cell lines obtained from the UNC Program in Melanoma subsequently indicated that cell lines indeed capture the miRNA biology of melanoma concordantly with FFPE samples. Numerous advantages clearly attend use of cell lines. We must now increase the number of data points substantially, hence our pilot grant application. Funding for confirmation of our preliminary results will promptly enable a scientific paper and applications to major funding sources.
|Funded by NIEHS Grant # P30 ES010126|