Abstract 4063: Potential targets of PTP4A3 involved in uveal melanoma migration

Abstract

Abstract Uveal melanoma (UM) is the most frequent eye cancer in the adulthood and it represents 4-5% of all melanomas. Although at diagnosis over 95% of patients have disease limited to the eye, about 50% will develop metastases after a median time of three years. From transcriptomic study, we identified PTP4A3/PRL3 level as an efficient predictor of patient's survival. Overexpression of PTP4A3 in UM OCM-1 increased both cell migration and invasiveness. We then got interested in identifying downstream targets of PTP4A3 and more precisely proteins linked to cytoskeleton. We first highlighted collapsin Response Mediator Protein (CRMP2) by 2-D electrophoresis of phosphorus-enriched UM OCM1 stably-expressing PTP4A3 or an inactive catalytic mutant of PTP4A3 (C104S). CRMP2 was dephosphorylated in presence of PTP4A3. CRMP2 expression in UM is inversely correlated with that of PTP4A3, suggesting an antagonistic role of these proteins in tumor progression. Through the use of shRNA in OCM-1, the downregulation of CRMP2 led to an increase in cell migration of PTP4A3-expressing OCM1. In addition, we focused on ATIP3, a protein encoded by the gene MTUS1, which binds to microtubules. In breast cancer, MTUS1 expression was shown to be downregulated in highly proliferative breast carcinomas of poor clinical outcome. Similarly, our transcriptomic analysis showed that expressions of PTP4A3 and MTUS1 were anti-correlated, suggesting that the reduction of MTUS1 gene and ATIP3 expression in UM would be of bad prognosis. In our OCM1 cells, we demonstrated that ATIP3 overexpression blocks proliferation however effect of ATIP3 overexpression on cell migration still need to be elucidaded.In conclusion, CRMP2 and ATIP3 may play a role in the metastatic process of UM tumors expressing high levels of the phosphatase. Citation Format: Geraldine Liot, Oceane Anezo, Cecile Laurent, Selma Maacha, Nathalie Planque, Simon Saule. Potential targets of PTP4A3 involved in uveal melanoma migration. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4063. doi:10.1158/1538-7445.AM2014-4063