Abstract 1844: MDM2 overexpression promotes angiogenesis and metastasis through dysregulation of MMP-9 and TIMP-1 pathway

MDM2 is a multifunctional oncogene that has been associated with highly prevalent and aggressive cancers such as colon and prostate. MDM2 promotes a negative regulation of p53 activities and thus can prevent several of p53 protective effects including DNA repair, cell cycle control and apoptosis. Several pharmacological blockers that target the N-terminal domain of MDM2 leading to a disruption of MDM2-p53 interaction are being developed. For instance, nutlin-3 is the prototype of this family and has been shown to confine the tumor growth in many cancer types. Recently, it has been confirmed that MDM2 also promotes metastasis and angiogenesis through activation of number of mediators such VEGF and HIF-1α. However, mounting evidence suggests that MDM2 has p53 independent functions. Therefore, understanding the mechanisms by which MDM2 promotes the metastatic ability of tumors might provide an invaluable therapeutic target and a potential prognostic biomarker. Particularly, MMP-9/TIMP-1 dysregulation has been known to be associated with cancer progression and metastasis. This system is involved in the digestion of extracellular matrix and thus a release of several sequestered cytokines and growth factors such as TGFβ1. Among the release cytokines, TGFβ1 has been proven to be involved in promoting the MMP-9 expression and consequent metastatic events. Therefore, we hypothized that MDM2 promotes angiogenesis and metastasis through dysregulation of TIMP-1/MMP-9 pathway. Hence, the goal of our study was to evaluate the influence of MDM2 on tumor angiogenesis and metastatic ability through dysregulation of TIMP-1/MMP-9 pathway. To test our hypothesis, LNCaP prostate cancer and MDM2-transfected LNCaP-MST cell lines were used. On the other hand, nutlin-3 at the dose of 20 μM for 24 hours were used to examine the influence of MDM2 in regulating MMP-9/TIMP-1 in LNCaP and LNCaP-MST cells. Utilizing qPCR and western blotting techniques, we obtained data which suggest that MDM2 positively regulates the expression of MMP-9 and negatively regulates TIMP-1. We observed that MMP-9 overexpressed in LNCaP-MST, and this overexpression was reversed after nutlin-3 treatment in LNCaP-MST by 0.40 fold. Conversely, the results showed a complete abolishment of TIMP-1 protein level in LNCaP-MST, and nutlin-3 does not seem to impact TIMP-1 level. The data suggest that MDM2 positively impacts MMP-9 in a p53 dependent fashion as opposed to TIMP-1, which is negatively regulated by MDM2 independent of p53. In the same connection, TGFβ1 overexpression was reversed by 0.51 fold in LNCaP-MST after nutlin-3 treatment as shown by the qPCR results. Altogether, this project would provide a significant insight into understanding cancer metastasis processes with respect to MDM2 activity (The financial support from the Royal Dames of Cancer Research Inc., Ft. Lauderdale is gratefully acknowledged). Citation Format: Ali Alaseem, Thiagarajan Venkatesan, Priya Dondapati, Saad Alobid, Appu Rathinavelu. MDM2 overexpression promotes angiogenesis and metastasis through dysregulation of MMP-9 and TIMP-1 pathway. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1844.