Abstract 1239: Intracellular effects of blocking MDM2 and HMG-CoA reductase in metastatic prostate cancer cells
Authors: Alsubhi Samia , Natarajan Umamaheswari , Alzahrani Amal , Alsarrani Ahmed , Rathinavelu Appu 
Published: June 2023

Our study aimed to analyze the effects of MDM2 inhibitor RG7388 and HMGCR inhibitor simvastatin, on EMT (epithelial to mesenchymal transition) and cancer stemness. Prostate Cancer (PCa) is the second leading cause of cancer death among men, ranked next to lung cancer in the United States of America. Aggressive growth, metastatic abilities, resistance, and reoccurrence are the main reasons for the most number of deaths among PCa patients. The proto-oncogene MDM2 controls multiple signaling pathways that are involved in the regulation of the cell cycle, proliferation, and survival of cancer cells. MDM2 also has a major role in imparting stemness and EMT abilities to PCa cells that are inherently less aggressive. During cancer growth, lipid metabolism is also known to play a pivotal role in cellular reprogramming, which eventually leads to the induction of EMT and the acquisition of stemness. It has been well documented that the intermediates of mevalonate metabolism can significantly affect gene expressions and influence the tumor microenvironment to support cancer growth and survival. Also, there is a lack of comprehensive knowledge about the use of RG7388 in cancers with p53 mutation since it is believed to be most effective in cancers with functional p53. Therefore, our study was designed to investigate the individual and combined effects of RG7388 and simvastatin in p53 mutant PCa cells. Western blot analysis technique was used to analyze the expression levels of mesenchymal and stem cell markers in PC3 and DU145 PCa cells, before and after they were treated with RG7388, simvastatin, or their combination. The MTT assay method was used to assess the cell viability of the PCa cells after 24 or 48 hours of treatment with different concentrations of RG7388 or simvastatin. Spheroid formation assay with stem cell marker analysis was performed following drug treatments. A scratch assay was also conducted to determine the inhibition of cancer cell migration by the above-mentioned drugs. Our experimental results showed a decrease in the viability of PC3 and DU145 cells, in a time and dose-dependent manner, after treatment with RG7388 or simvastatin. The mesenchymal and stem cell markers were also downregulated along with the disintegration of spheroids causing a reduction in the total number of spheroids and colonies after RG7388, simvastatin, and combination treatments. Immunofluorescence staining of spheroids revealed a significant downregulation of cancer stem cell markers among all treated groups. Furthermore, the scratch assay showed inhibition of migration of the PCa cells, particularly after the combination treatments. Our results have confirmed that RG7388, simvastatin, and their combination treatments can reverse EMT, inhibit migration, and reduce cancer stemness in p53 mutant prostate cancer cells. (This research was supported by the Royal Dames of Cancer Research Inc. of Ft. Lauderdale, Florida).

Citation Format: Samia Alsubhi, Umamaheswari Natarajan, Amal Alzahrani, Ahmed Alsarrani, Appu Rathinavelu. Intracellular effects of blocking MDM2 and HMG-CoA reductase in metastatic prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1239.