MP38-08 SELECTIVE LYSINE SPECIFIC DEMETHYLASE 1 INHIBITOR, NCL1, COULD CAUSE TESTICULAR TOXICITY VIA THE REGULATION OF APOPTOSIS

Abstract

INTRODUCTION AND OBJECTIVE: Recent studies show that epigenetic alterations, such as lysine-specific demethylase 1 (LSD1), lead to oncogenic activation, suggesting such alterations as therapeutic target molecules. However, studies evaluating the effect of LSD1 inhibitors on male fertility are lacking. Here, we first analyzed the potential toxicity of new selective LSD1 inhibitor, NCL1, in the testis. METHODS: Immunohistochemistry of LSD1 using human testicular samples was undertaken. Six-week-old male C57BL/6J mice were injected intraperitoneally with dimethyl sulfoxide vehicle, 1.0 mg/kg, or 3.0 mg/kg NCL1 twice a week, and 20 mg/kg busulfan once. After five weeks, testicular toxicity and protein expression were analyzed in testicular and blood samples. Cell viability, flow cytometry, and western blot analyses of GC-1, TM3, and TM4 cell lines treated with NCL1 were also undertaken. RESULTS: In human samples, LSD1 was mainly expressed in Sertoli and germ cells, with intensity levels significantly decreasing in a progressively meiosis-dependent manner. Expression patterns among germ cells were similar in normal spermatogenesis, late maturation arrest, and early maturation arrest. Histological examination revealed significantly increased abnormal seminiferous tubules in busulfan and 3.0 mg/kg NCL1- treated mice compared to control; cellular detachment, sloughing, vacuolization, eosinophilic changes and TUNEL-positive cells were significantly greater. NCL1 also reduced serum total testosterone levels. Western blot of mouse testicular samples revealed NCL1 induced an elevation in cleaved caspases 3, 7, and 8, and expression of connexin 43 proteins. NCL1 significantly reduced the cell viability of GC-1, by apoptosis, but not TM3 and TM4 cell lines in a dose-dependent manner. CONCLUSIONS: High-dose NCL1 targeting LSD1 caused dysfunctional spermatogenesis and induced caspase-dependent apoptosis. These results add to our knowledge of the effect of LSD1 inhibitors on male fertility.Source of Funding: none