Abstract 80: Analysis of the regulation of angiogenesis pathway by inhibiting MDM2 function in LNCaP-MST prostate cancer cells using PCR array
Authors: Alaseem Ali , Venkatesan Thiagarajan , Alhazzani Khalid , Rathinavelu Appu 
Published: August 2015

Interfering with angiogenesis is a well-known strategy for cancer treatment due the fact that this process is essential for promoting cancer growth and metastatic spread by providing adequate supply of oxygen and nutrients to the tumor cells. The process of angiogenesis is highly regulated by both activator and inhibitor genes through their corresponding proteins. One of the suspected promoters of angiogenesis is MDM2 (Murine Double Minute 2 gene). The overexpression of MDM2 has been found in many cancer types and also correlated well with poor prognosis of certain cancers. In addition to some of the newly emerging mechanistic abilities, MDM2 is well known to regulate p53 levels and its functions by dual mechanisms, which plays a major role in many cellular processes such as cell cycle control and apoptosis. However, the role for MDM2 in regulating angiogenesis is slowly evolving which can explain the potential metastatic status of the cancer where there is no p53 mutation. In this connection, to further understand its role in tumor angiogenesis, the status of MMP9 (Matrix metallopeptidase 9 also called gelatinase B), THSB1 (Thrombospondin 1), TGB1 (Transforming growth factor-beta 1) were studied, by inhibiting MDM2. The ultimate goal of our study was to determine how the angiogenesis pathway is regulated by the overexpression of MDM2. To explore the possible mechanisms, LNCaP (prostate cancer cells), and LNCaP-MST (MDM2 transfected prostate cancer cells) cells were treated with Nutlin-3 (20 uM for 24 hours). Indeed LNCaP-MST cells are known to show 10 times higher expression of MDM2 compared to LNCaP cells. Therefore, Nutlin-3 treatment was expected to inhibit the interaction between p53 and MDM2 in these cells and thereby impact the expression of angiogenesis pathway related genes. When we analyzed the gene expression profile using a PCR array that was designed to explore the above mentioned pathway we were able to confirm that MDM2 overexpression could positively regulate MMP9, THSB1, and TGB1 levels in a highly significant manner. Interestingly, the genes expression profile that was found to be elevated in LNCaP-MST cells was reversed after Nutlin-3 treatment confirming that some of these angiogenesis related genes are positively regulated by MDM2 overexpression. In Conclusion, we are proposing that targeting MDM2 can effectively control the pro-angiogenesis mechanisms that can be found activated in MDM2 positive cancer types. We are conducting further studies to fully unravel the role of MDM2 in promoting tumor angiogenesis and metastatic ability (The financial support from the Royal Dames of Cancer Research Inc., Ft. Lauderdale is gratefully acknowledged).

Citation Format: Ali Alaseem, Thiagarajan Venkatesan, Khalid Alhazzani, Appu Rathinavelu. Analysis of the regulation of angiogenesis pathway by inhibiting MDM2 function in LNCaP-MST prostate cancer cells using PCR array. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 80. doi:10.1158/1538-7445.AM2015-80