S Kashyap1, J Jha1, M K Singh1, L Singh2, S Sen1, J Kaur3, M S Bajaj4, N Pushker5. 1. Department of Ocular Pathology, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. 2. Department of Biosciences, JMI, New Delhi, India. 3. Department of Ocular Biochemistry, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. 4. Department of Ophthalmology, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. 5. Department of Ophthalmology, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. pushkern@hotmail.com.
Abstract
BACKGROUND: The role of DNA damage response (DDR) proteins is poorly understood in uveal melanoma. ATR belongs to one of those proteins that induce DDR by arresting the cell cycle which leads to DNA repair. ATR is localized at position 23 on the same chromosome 3 where BAP1 is located at position 21.1 which is a known poor prognostic marker of UM. The aim of our study is to detect the expression of ATR at the protein and RNA levels and determine its prognostic significance. METHODS: Expression of nuclear ATR was investigated on sixty-nine UM patients. Formalin-fixed paraffin-embedded choroidal melanoma samples were taken to evaluate the expression of ATR. Fifty samples were also validated by real-time PCR. Results of both protein and mRNA were then correlated with clinicopathological parameters. To determine the prognostic significance, Kaplan-Meier and multivariate analyses were performed. RESULTS: Loss of ATR protein was seen in 72% cases which was statistically significant with epithelioid cell type (p = 0.005), tumor thickness (p = 0.016), mitotic figures (p = 0.001) and BAP1 loss (p < 0.001). At the transcriptional level loss of ATR was seen in 76% cases which were statistically significant with metastasis (p = 0.046), staging (0.044) and loss of BAP1 (p = 0.022). On multivariate analysis loss of ATR and tumor staging came out to be independent prognostic parameters. CONCLUSION: Our data suggest that ATR might serve as a potential prognostic marker in UM patients and could serve as a potential therapeutic target.
BACKGROUND: The role of DNA damage response (DDR) proteins is poorly understood in uveal melanoma. ATR belongs to one of those proteins that induce DDR by arresting the cell cycle which leads to DNA repair. ATR is localized at position 23 on the same chromosome 3 where BAP1 is located at position 21.1 which is a known poor prognostic marker of UM. The aim of our study is to detect the expression of ATR at the protein and RNA levels and determine its prognostic significance. METHODS: Expression of nuclear ATR was investigated on sixty-nine UM patients. Formalin-fixed paraffin-embedded choroidal melanoma samples were taken to evaluate the expression of ATR. Fifty samples were also validated by real-time PCR. Results of both protein and mRNA were then correlated with clinicopathological parameters. To determine the prognostic significance, Kaplan-Meier and multivariate analyses were performed. RESULTS: Loss of ATR protein was seen in 72% cases which was statistically significant with epithelioid cell type (p = 0.005), tumor thickness (p = 0.016), mitotic figures (p = 0.001) and BAP1 loss (p < 0.001). At the transcriptional level loss of ATR was seen in 76% cases which were statistically significant with metastasis (p = 0.046), staging (0.044) and loss of BAP1 (p = 0.022). On multivariate analysis loss of ATR and tumor staging came out to be independent prognostic parameters. CONCLUSION: Our data suggest that ATR might serve as a potential prognostic marker in UM patients and could serve as a potential therapeutic target.