Presentation Authors: Ashish Tyagi, Balaji Chandrasekaran, Venkatesh Kolluru, Samarpit Rai, Murali Ankem, Adrienne Jordan, Houda Alatassi, Jamie Messer, Chendil Damodaran, Ahmed Haddad*, Louisville, KY
Introduction: The role of androgen receptor (AR) signaling in bladder cancer (BCa) is not fully characterized. This study aimed to delineate the role of AR signaling in BCa and to determine whether the combination of AR inhibitor Enzalutamide (Enz), and Cisplatin (Cis) efficiently inhibit the growth of muscle-invasive bladder cancer (MIBC) cells.
Methods: AR expression was determined in 89 human urothelial BCa specimens by immunohistochemistry. A panel of BCa cell lines were treated with Cis, Enz, or a combination of both (Enz+Cis). We determined the expression of AR, changes in apoptotic signaling, DNA damage, and analyzed effect on epithelial mesenchymal transformation markers.
Results: AR expression was detected in 61.4% of tumors from male BCa patients. Enz inhibited proliferation of the AR+ bladder cancer cell lines TCCSUP (IC50 4.4 Î¼M) and J82 (IC50 6.6Î¼M) (Fig 1A &B). Enz at IC50 concentration induced apoptosis in TCCSUP cells (26%, p=0.0201) and J82 cells (15%, p=0.0386)(Fig.1C & 1D). The combination of Enz+Cis synergistically inhibited the proliferation of BCa cells even at low concentrations (5μM of Cis and 1.25 Î¼M of Enz) (Fig 1A & 1B). The combination of Enz and Cis at these low concentrations induced apoptosis in AR+ TCCSUP and J82 cells to a greater degree than individual agent alone at IC50 concentration (Fig.1C &1D). 5μM of Cis and 1.25 Î¼M of Enz in combination induced protein expression of BAX, Cleaved Caspase3, and Cleaved PARP in both cell lines. Bcl-2 protein expression was inhibited by Enz+Cis. Enz+Cis also increased DNA damage response regulators ATM, ATR, phos-Histone1 and phosphorylated checkpoint kinase-1 (CHK1). Invasive and migratory potential of TCCSUP and J82 cells were reduced with Enz+Cis treatment, and associated with down-regulation of mesenchymal markers.
Conclusions: A high percentage of the bladder tumors from male patients in our cohort expressed AR. Inhibition of AR with Enz in combination with Cis resulted in growth inhibition, induction of apoptosis and DNA damage response regulators and abrogation of invasive potential in AR+ BCa cell lines. Our studies suggest that a combination of Enz+Cis may be useful in treating patients with AR+ bladder cancer.