Abstract 1595: HMGA2 induces EMT in prostate cancer cells and may be antagonized by camalexin

Abstract

Abstract Prostate cancer is the most diagnosed cancer in men and the second leading cause of death in the United States. African American men have the highest incidence and mortality rates of prostate cancer compared to any other race. Epithelial-mesenchymal transition (EMT) plays a critical role in cancer progression and metastasis. Mesenchymal cells are migratory, invasive, and more resistant to apoptosis. Reactive Oxygen Species (ROS) has been shown to promote EMT. High mobility group A (HMGA2) is a non-histone protein that is highly expressed during the embryogenesis, whereas the gene expression is very low or absent during adulthood. Recent studies have been reported an overexpression of HMGA2 protein in malignant cancers. Loss of Let-7 miRNA (repressor of HMGA2) has been found to induce EMT via upregulation of HMGA2 in prostate cancer. There has been no link between ROS and HMGA2. We have reported that camalexin, a 3-thizol-2-yl-indole, may be a candidate treatment for aggressive prostate cancer cells by ROS-mediated apoptosis. The study demonstrated that treating the prostate cancer cell with camalexin increased ROS levels which contributed to decreased cell proliferation and increased apoptosis. We hypothesize that HMGA2 may regulate EMT in part by inducing ROS and that camalexin may antagonize HMGA2 signaling. We analysed HMGA2 and EMT marker expression in a panel of prostate cancer cell lines by western blot analysis. We also transiently and stably overexpressed wild-type HMGA2 and mutant HMGA2 (missing Let-7 binding site) in LNCaP cells. We measured ROS levels using DCFDA dye that detects hydrogen peroxide. We treated ARCaP-M (mesenchymal) cells with different concentrations of camalexin to analyse HMGA2 expression. Our results showed that HMGA2 is highly expressed in aggressive prostate cancer cell lines (C4-2, ARCaP, E006AA) as compared to RWPE1 and LNCaP cells. The transient overexpression of HMGA2 in LNCaP cells decreased E-cadherin more markedly than with mutant HMGA2 but did not show any changes in ROS. We will repeat this experiment with stable clones from HMGA2 overexpression. ARCaP-M cells treated with camalexin induced ROS and decreased HMGA2 expression. We are currently performing in vivo studies using ARCaP-M cells injected subcutaneously into nude mice followed by treatment with camalexin after the tumor grows to 50 mm3. In conclusion, HMGA2 promotes EMT, even more markedly if its Let-7 suppressor binding site is eliminated, and camalexin may target HMGA2 to decrease prostate cancer progression. GRANT SUPPORT: 1P20MD002285; 8G12MD007590 Citation Format: Ohuod A. hawsawi, Basil Smith, Jodi Dougan, Liza J. Burton, Valerie A. Odero-Marah. HMGA2 induces EMT in prostate cancer cells and may be antagonized by camalexin. [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 1595.