Figure 2. LSD1’s catalytic function is dispensable for promoting NEPC cell survival.

(A) SP2509 was tested by dose response in a panel of prostate cancer cell lines for 72 hours. Cell viability was measured by CTG. IC₅₀ values are shown. The # symbol indicates that CA-HPV-10 and PC-346C did not reach IC₅₀ using doses up to 10 μM of SP2509. (B) IC₅₀ values of NEPC and adenocarcinoma cell line models in NEPC cell lines (green) and adenocarcinoma cell lines (orange). Data are reported as the median, with 95% CI. For statistical analysis, 2-tailed Mann-Whitney U test was performed. **P < 0.01. (C) The indicated NEPC cells were treated with 600 nM SP2509 for 48 hours, and H3K4me2 levels were measured by Western blot analysis. Total histone H3 levels were used as loading controls. (D–I) LNCaP–N-Myc or MR42D cells stably expressing empty vector, WT LSD1, or catalytically inactive mutant LSD1 (K661A) were transfected with nontargeting control (NTC) or siRNA targeting the 3′ UTR of LSD1. Knockdown of endogenous LSD1 was confirmed with primers specific to the 3′ UTR of endogenous LSD1 transcript (D and E). Overexpression of ectopic LSD1 was confirmed with primers specific to ectopic transcripts (F and G). Cell viability was measured 96 hours after transfection by cell counting with trypan blue exclusion method (H and I). n = 3. Data are reported as the mean ± SD. For statistical analysis, unpaired 2-tailed Welch’s t tests were performed, and P values are indicated.