Introduction

Lysine-specific demethylase 1 (LSD1), the first identified histone demethylase, is a novel target for prostate cancer therapy. Herein we examined the anticancer effects of NCL1 and NCD38, the selective inhibitors of LSD1 that were first discovered at our university.

Methods

Various tests using LNCaP (a hormone-sensitive prostate cancer cell line) and PCai1 (a castration-resistant prostate cancer [CRPC] cell line established in our institute) cells were used to confirm the anticancer effects of NCL1 and NCD38. Cell viability was assessed by performing a WST assay in the presence of NCL1, NCD38, or a standard vehicle (control). Chromatin immunoprecipitation (ChIP) and PCR were used to confirm the methylation status. For autophagy analysis, LNCaP and PCai1 cells were incubated with or without CQ in the presence or absence of NCL1. Subsequently, transmission electron microscopy (TEM), fluorescent immunocytochemistry, and WST assay were performed with the treated and non-treated cells. A combination index analysis was performed to assess the effects of NCL1 and CQ. Lastly, the effect on xenograft tumors in CRPC mice models was measured by subcutaneously injecting castrated nude mice with PCai1 cells. Mice were injected intraperitoneally with NCL1, NCD38, CQ, or the vehicle, and subsequent growth was recorded.

Results

WST assay revealed a reduction in the number of viable cells after NCL1 and NCD38 treatment. ChIP showed NCL1-induced H3K9me2 accumulation at the ELK4 and KLK2 promoters, whereas a dose-dependent induction of apoptosis by NCL1 was noted by flow cytometry. Autophagosomes were observed in LNCaP cells treated with NCL1. The expression level of LC3-II was significantly increased in cells treated with NCL1 and CQ. Furthermore, the combination of NCL1 and CQ significantly decreased cell growth in vitro, but had no synergistic effect in vivo. Xenograft tumor volume was reduced in the NCL1 and NCD38-treated mice when compared with the controls; no adverse effects were observed.

Conclusions

Castration resistant prostate cancer growth was effectively suppressed with NCL1 and NCD38 both in vitro and in vivo, without any adverse events, via regulation of apoptosis and autophagy; thus, indicating the potential use of LSD1 inhibitors as therapeutic agents for prostate cancer.

Funding

None.