Abstract 1341: Rapid decrease of ATP followed by necrosis-like cell death in bladder cancer cells after exposure to high-dose chemotherapeutics used in intravesical therapy

Abstract

Abstract Objectives) Non-muscle invasive bladder cancer is often treated by intravesical chemotherapy following transurethral resection. Mechanism of the effect of intravesical chemotherapy remains elusive. In this experiment, we studied cell death mechanism induced by high-dose chemotherapeutics using a novel culture method for primary cancer cells. Materials and methods) We have developed a new culture method which enables preparation and culture of primary cancer cells as multicellular spheroids which are termed cancer tissue-originated spheroids (CTOSs) (Okuyama 2013 J Urol). First we generated a bladder cancer patient-derived xenograft. We prepared CTOS from the xenograft, and exposed to high-dose (1mg/ml) or low-dose (0.01mg/ml) of epirubicin (e-ADM) or mitomycin C (MMC) for 2 hours. We investigated absorption of chemotherapeutics into CTOSs and assessed the mode of cell death. Next, we prepared CTOSs directly from surgical specimens of bladder cancer and tested the individual responses after exposure to high-dose e-ADM and MMC. Results) At high dose, e-ADM was promptly and homogenously delivered into cancer cells in the CTOSs. High-dose e-ADM and MMC decreased ATP levels in CTOSs within an hour accompanied with mitochondrial swelling and reduction of mitochondrial membrane potential, while plasma membrane integrity was mainteined. Some of the molecules in mitochondrial apoptotic pathway were subsequently activated, while at later time point the cells lost integrity of cell membrane without DNA laddering. In contrast, CTOSs exposed to low-dose of e-ADM or MMC exhibited typical DNA laddering. Intriguingly, the decrease of ATP levels by e-ADM and MMC was varied among CTOSs derived from 20 surgical specimens. Conclusions) High-dose chemotherapeutics used in intravesical therapy may induce necrosis-like cell death, different from typical apoptosis caused by chemotherapeutics at the dose of systemic chemotherapy. Each bladder cancer may have a different response to high-dose chemotherapeutics used in intravesical therapy, indicating necessity of chemosensitivity test aiming for personalized medicine. Citation Format: Takahiro Yoshida, Hiroaki Okuyama, Masashi Nakayama, Kazuo Nishimura, Norio Nonomura, Masahiro Inoue. Rapid decrease of ATP followed by necrosis-like cell death in bladder cancer cells after exposure to high-dose chemotherapeutics used in intravesical therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1341. doi:10.1158/1538-7445.AM2014-1341