MP11-03 NOVEL SELECTIVE LYSINE-SPECIFIC DEMETHYLASE 1 INHIBITORS SUPPRESS TESTICULAR TUMOR CELL PROLIFERATION

Abstract

INTRODUCTION AND OBJECTIVE: Lysine-specific demethylase 1 (LSD1), the first histone demethylase to be discovered, is a novel target in prostate cancer therapy. NCL1 and NCD38, novel selective cell-active inhibitors of LSD1, were discovered at our university. We analyzed the efficacy of LSD1 inhibitors in germ cell tumors in vitro and in vivo. METHODS: Various tests were used to uncover mechanism of germ cell tumor growth and anticancer effects of NCL1 and NCD38. Cell viability was assessed using a WST-8 assay with standard vehicle, NCL1 or NCD38 in NTERA2 and Tera-1 cells (human testicular embryonal carcinoma cell lines). Flow cytometry and western blotting were performed to assess apoptosis and the cell cycle after treatment of NTERA2 cells with NCL1 or NCD38. Subcutaneous tumors were induced by subcutaneously injecting nude mice with NTERA2 cells. Thereafter, mice were injected intraperitoneally with vehicle, NCL1 or NCD38, twice a week, and their subsequent growth recorded. TUNEL staining was used to detect apoptosis in tumors. Finally, tissue arrays were prepared from tissue specimens from 35 patients with seminoma who underwent orchiectomy. RESULTS: The WST assay revealed a reduction in the number of viable cells in a dose-dependent manner after NCL1 or NCD38 treatment. In western blotting, NCL1 or NCD38 treatment induced caspase-dependent apoptosis, while Oct4 and SOX2 expression was decreased. In flow cytometry analysis, NCL1 or NCD38 significantly induced apoptosis in a dose-dependent manner. Subcutaneous tumor volumes and serum AFP levels were significantly lower in mice treated with NCL1 or NCD38 than in controls. TUNEL analysis showed that NCL1 and NCD38 treatment induced apoptosis in NTERA2 subcutaneous tumors. No adverse effect was observed in body weights, blood tests, and hematoxylin-eosin staining of various organs in mice. Tissue array analysis showed that LSD1 expression in human seminoma specimens was significantly higher than that in noncancerous specimens. CONCLUSIONS: Germ cell tumor growth was effectively suppressed with NCL1 or NCD38 treatment in vitro and in vivo without adverse events by regulating apoptosis and suppressing SOX2 and Oct4. These results indicate the potential of NCL1 and NCD38 as therapeutic agents for germ cell tumors.Source of Funding: Grant-in-Aid for Scientific Research 17K11152