Abstract 2013: Increased MMPs activity in MDM2 overexpressing cancer cell lines
Authors: Alaseem Ali , Venkatesan Thiagarajan , Kanagasabai Thanigaivelan , Alhazzani Khalid , Alobid Saad , Dondapati Priya , Rathinavelu Appu 
Published: July 2017

The matrix metalloprotenases (MMPs) are a family of zinc-dependent endopeptidase and have proteolysis activity which found to impact several physiological and pathophysiological conditions including cancer. In cancer, over 20 types of MMPs promote invasion, angiogenesis, metastasis, and proliferation. For instance, MMP-9 is involved in many processes such as wound healing, tissue remodeling and regulation of inflammation. So far, several studies have also shown that MMP-9 is associated with poor clinical outcome. MMP-9 can facilitate angiogenesis and metastasis by releasing cytokines, pro-angiogenic and pro-metastatic factors. Conversely, the tissue inhibitor of metalloproteinases (TIMP-1) is a well-known negative regulator of MMPs which can also modulate other biological functions independent of MMPs regulation. TIMP-1 dysregulation has been shown to impact ECM integrity and potentiate metastatic ability also. Similarly, MDM2 (Murine Double Minute) has been recognized as an important multi-domain protooncogene which is overexpressed in many types of cancer and is associated with poor prognosis in different tumor types including sarcomas and carcinomas. Previously, our group reported that MDM2 overexpression is regulating MMP-9/TIMP-1 axis in LNCaP and LNCaP-MST (MDM2 transfected) prostate cancer cells. In order to further analyze the status of MMP in MDM2 overexpressing cancers the fluorescence activity assay and the zymography assay were used for measuring the activity of MMPs including MMP-9. Immunoblotting analysis were also used to correlate the expression levels of MDM2, MMP-9, and TIMP-1 in MDM2 overexpressing cell lines with and without Nutlin-3 (20 uM) treatment. Our results indicated that MMP activity is elevated by 97.3 % in LNCaP-MST cells compared to LNCaP. This may be possibly due to the near knockdown levels of TIMP-1 that was observed in LNCaP-MST cells. However, the Nutlin 3 treatment was able to decrease the MMP-9 levels and activity only marginally, without elevating TIMP-1 levels. This suggests that, in addition to MDM2, the PTEN loss in LNCaP-MST cells may also play a role in regulating the levels of TIMP-1 and consequently the activity of MMP-9. Furthermore, in order to verify our original speculation, we analyzed the levels of TIMP-1 in SJSA1 and GI-101A cell lines, which are known to overexpress MDM2 and impart aggressive metastatic abilities. Interestingly, the levels of TIMP-1 were found to be elevated in both SJSA1 and GI-101A cell lines compared to LNCaP-MST cells. This finding indicates that TIMP-1 may paly dual role depending on cancer types and the gene expression status in the tumor microenvironment. Further studies are required to fully delineate the interplay between MDM2 and pro-metastatic mechanisms, including the expression of TIMP-1 and MMP-9. (The financial support from the Royal Dames of Cancer Research Inc., Ft. Lauderdale is gratefully acknowledged).

Citation Format: Ali Alaseem, Thiagarajan Venkatesan, Thanigaivelan Kanagasabai, Khalid Alhazzani, Saad Alobid, Priya Dondapati, Appu Rathinavelu. Increased MMPs activity in MDM2 overexpressing cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2013. doi:10.1158/1538-7445.AM2017-2013