SP-2509

Functionally, dual pharmacological inhibition of EZH2 (GSK126) and LSD1 (SP2509) suppressed HCC cell proliferation, induced G1-phase arrest, and enhanced apoptosis, as evidenced by increased caspase-3/7 activity and decreased pro-caspase levels. Chromatin immunoprecipitation revealed reduced EZH2, LSD1, and STAT3 occupancy at the GLI1 promoter following dual inhibition, leading to the repression of GLI1 and its downstream targets. Collectively, these findings demonstrate that EZH2 and LSD1 cooperatively sustain GLI1-dependent SHH signaling in HCC, and that dual epigenetic inhibition represents a mechanistically defined therapeutic strategy.

Combined inhibition of LSD1 and PARP1, using SP2509/SP2577 and olaparib, respectively, synergistically hinders NER, induces apoptosis, reduces tumor burden, and prolongs the survival of multiple BAP1-deficient pancancer in vitro models and in vivo xenografts. In conclusion, our results provide a deubiquitination landscape of BAP1; elucidate the mechanisms of action of BAP1, LSD1, and PARP1 in pancancers; and describe a promising combination therapeutic strategy applicable across multiple cancers with BAP1 mutations.

Given the association of epigenetic regulation with chemotherapy resistance and cancer progression, this study aims to identify epigenetic vulnerabilities in two CRPC cell lines (DU145 and 22Rv1) established as resistant to two different taxanes, docetaxel (Dtx) and cabazitaxel (Cbz), using a small-molecule screening approach...Combination assays demonstrated that both compounds potentiated Dtx activity and helped overcome resistance in taxane-resistant CRPC models. This study highlights epigenetic vulnerabilities in taxane-resistant CRPC and identifies 4-Iodo-SAHA and SP2509 as promising monotherapy candidates, demonstrating their ability to potentiate Dtx activity and overcome resistance.

The noncompetitive lysine-specific demethylase 1 (LSD1) inhibitors SP-2509 and SP-2577 are N'-(1-phenylethylidene)-benzohydrazides that display potent activity in Ewing sarcoma. This unique activity is instead associated with the N'-(2-hydroxybenzylidene)-benzohydrazide core and destabilization of Fe-S proteins. These findings reveal a novel mechanism of action for this class of compounds and raise additional questions regarding how EWSR1::FLI1 transcriptional regulation is linked to Fe-S biogenesis, the precise mechanisms of cell death, the biological features of susceptible cancer cells, and strategies for clinical translation.

Treatment with the small molecule SP-2509 results in reversal of the transcriptional activity of the FET fusion that causes Ewing sarcoma, EWSR1::FLI1. This included reversal of FET-fusion transcriptional signatures for EWSR1::WT1, EWSR1::ATF1, and EWSR1::ERG. Though novel inhibitors are unlikely to display single-agent efficacy in the clinic, these data suggest seclidemstat remains a promising new treatment strategy for patients with FET-rearranged and other fusion positive sarcomas.

The noncompetitive LSD1 inhibitors SP-2509 and SP-2577 are N'-(1-phenylethylidene)-benzohydrazides that display potent activity in Ewing sarcoma. This unique activity is instead associated with the N'-(2-hydroxybenzylidene)-hydrazide core and destabilization of Fe-S proteins. These findings reveal a novel mechanism of action for this class of compounds and raise additional questions regarding how EWSR1::FLI1 transcriptional regulation is linked to Fe-S biogenesis, the precise mechanisms of cell death, the biological features of susceptible cancer cells, and strategies for clinical translation.

LSD1 inhibition by SP2509 disrupted cell cycle, reduced immunosuppression, and enhanced CD4+ and CD8+ T-cell infiltration. In a feline model of spontaneous OSCC, a clinical LSD1 inhibitor (Seclidemstat or SP2577) was found to be safe and effectively inhibit the STAT3 network...Notably, LSD1 inhibition reduced the phosphorylation of CDK7 at Tyr170 and eIF4B at Ser422, offering insights into a novel mechanism by which LSD1 regulates the preneoplastic-to-OSCC transition. This study provides a deeper understanding of OSCC progression and highlights LSD1 as a potential therapeutic target for controlling OSCC progression from preneoplastic lesions.

SP2509, a histone demethylase inhibitor, effectively reversed the downregulation of lysosomal and mitochondrial genes caused by loss of Men1. Our study confirms the previously unrecognized biological and mechanistic importance of menin-mediated H3K4me3 in maintaining organelle homeostasis.

Notably, we report that SP2509, an allosteric inhibitor of the demethylase-independent function of LSD1 (a TBX2-interacting protein in the COREST complex) disrupts both TBX2-LSD1 and TBX2-GR protein-protein interactions, revealing a unique mode of SP2509 action in CRPC. Taken together, our study identifies the TBX2-driven AR- to GR- signaling switch as a molecular mechanism underlying enzalutamide resistance and provides key insights into a potential therapeutic approach for targeting this switch by disrupting TBX2-GR and TBX2-LSD1 protein-protein interactions.

Western blot analysis show that treatment with chemotherapy drugs cisplatin, carboplatin, and paclitaxel increased KDM1A expression in OCa cells. KDM1A knockdown (KD) or treatment with KDM1A inhibitors NCD38 and SP2509 sensitized established and patient-derived OCa cells to chemotherapy drugs in reducing cell viability and clonogenic survival and inducing apoptosis...Importantly, KDM1A-KD, in combination with cisplatin, significantly reduced tumor growth compared to a single treatment in an orthotopic intrabursal OCa xenograft model. Collectively, these findings suggest that combination of KDM1A inhibitors with chemotherapy could be a promising therapeutic approach for the treatment of OCa.

We further demonstrated that SP-2509 and OG-L002 disturbed fatty acid metabolism and induced lipid droplet accumulation through the impairment of lipophagy, but not bulk autophagy. These findings indicate a significant potential association of lipophagy and anticancer effects in glycolysis-suppressed PDAC cells, offering ideas for new therapeutic strategies for PDAC by dual inhibition of glycolysis and fatty acids metabolism.

The present study preclinically demonstrated that LSD1 inhibition could provide a valuable strategy to enhance PI sensitivity and overcome drug resistance in MM patients and that this combination might be exploited for the treatment of other B-cell malignancies, thus extending the therapeutic impact of the project.