Background and aims: PTPRG was identified as a candidate tumor suppressor gene. It belongs to a family of membrane-bound receptor tyrosine phosphatases. However, the function and the dephosphorylation targets of PTPRG still remain to be elucidated. The aim of this current study was to identify the downstream dephosphorylation targets of PTPRG. Methods: A tetracycline-inducible system was used to obtain PTPRG-expressing clones. The dephosphorylation targets were identified by an antibody array. The anti-angiogenesis function of PTPRG was investigated by HUVEC tube formation assay. Results: The c-jun phosphorylation level was found to be down-regulated after re-expression of PTPRG. Re-expression of PTPRG can inhibit tube formation in the HUVEC tube formation assay by down-regulating the AP1 downstream target, VEGF, secretion. Conclusions: Re-expression of PTPRG can reduce the phosphorylation of c-jun and, thus, inhibit angiogenesis by down-regulating the important angiogenesis regulator, VEGF. The results suggest the importance of PTPRG in regulating tumor formation. It is a good candidate tumor suppressor gene, which warrants further study. Acknowledgements: This work was supported by the Research Grants Council and the University Grants Council of the Hong Kong Special Administrative Region, People's Republic of China (AoE/M-06/08, to M.L.L.) and the University of Hong Kong Small Project Fund (Grant 200907176081, to A.K.L.C.).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4002. doi:1538-7445.AM2012-4002