Findings suggest that PK83 suppresses MYCN expression and preferentially affects MYCN-high HCC cells in a p53-independent manner, warranting further preclinical investigation of PK83 and related compounds in MYCN-associated cancers.
Abstract
MYCN is a key oncogenic driver in hepatocellular carcinoma (HCC) and a therapeutic challenge due to the historical undruggability of MYC transcription factors (TFs). Using a high-throughput MYCN promoter-luciferase reporter, we identified PhiKan 083 (PK83), a small molecule previously recognized as a mutant p53 activator, that dose-dependently suppresses MYCN expression in HCC cells. PK83 impaired the proliferation and survival of MYCN-high HCC cells, inducing DNA damage, apoptosis, and loss of clonogenic and spheroid growth potential, while sparing MYCN-low HCC cells and normal hepatocytes. Structure-activity analysis revealed that polar, hydrogen-bond-capable substituents on PK83's tricyclic scaffold are critical for its activity. Although PK83 broadly activates p53 signaling, its cytotoxicity in MYCN-high cells is not strictly dependent on intact p53, as confirmed in p53-knockout systems. Transcriptome profiling and pathway analysis demonstrated robust suppression of MYC/MYCN targets along with modulation of pathways linked to stress, differentiation, and metabolism. In primary HCC tumors, PK83-downregulated TFs, including oncogenic TFs ZMIZ1 and TARBP1, positively correlated with MYCN, whereas upregulated stress-responsive TFs ATF3 and FOSL2 showed a negative correlation. These findings suggest that PK83 suppresses MYCN expression and preferentially affects MYCN-high HCC cells in a p53-independent manner, warranting further preclinical investigation of PK83 and related compounds in MYCN-associated cancers.
Purpose Amplification of MYCN is a primary driver of aggressive retinoblastoma (RB), yet it remains a challenging therapeutic target. This study aimed to evaluate the therapeutic potential of the PROTAC molecule HLB-0532259 in degrading MYCN and suppressing RB growth. Methods Y79 and WERI-Rb1 RB cell lines were treated with HLB-0532259, and MYCN protein degradation, cell viability, and time-dependent transcriptional changes were assessed by Western blotting, cell viability assays, RNA-seq, and proteomics. The therapeutic potential was further validated in an orthotopic Y79 xenograft mouse model through intravitreal administration, with tumor burden evaluated by histology and immunohistochemistry. Results HLB-0532259 induced dose-dependent degradation of MYCN in both cell lines, with Y79 cells showing higher sensitivity. Transcriptomic and proteomic analyses revealed rapid activation of the p53–p21 pathway, downregulation of DNA repair and epigenetic regulators, and accumulation of DNA damage. Proteomic profiling confirmed upregulation of senescence-associated secretory phenotype factors and downregulation of MYCN-dependent effectors, including HMGA1 and TRAF6. In orthotopic xenografts, intravitreal administration of HLB-0532259 reduced intraocular tumor burden, decreased Ki-67 and MYCN-positive cells, and activated p53, p21, and NF-κB signaling. Conclusions Targeted MYCN degradation by HLB-0532259 effectively inhibits RB growth and induces a DNA damage–associated senescence program, highlighting targeted MYCN degradation as a promising therapeutic strategy for MYCN-driven RB.
This study elucidates a therapeutically targetable KPNB1-p65-Bcl-2 survival axis in multiple cancers and establishes a foundation for developing next-generation KPNB1 inhibitors.
Cong Li, Qiaohua Yan, Muhammad Muddasar Saeed et al.· Cell Chemical Biology· 0 citations
Clinically, these findings not only deepen the understanding of m6A-mediated posttranscriptional regulation in CRC but also identify this axis as a promising therapeutic target for overcoming ferroptosis resistance and improving patient outcomes.
Li-Chun Wang, Bin Guo, Xue-Ping Jiao et al.· Current Gene Therapy· 0 citations
Background Although cullin-family E3 ubiquitin ligases regulate diverse oncogenic pathways, the role of CACUL1 in hepatocellular carcinoma (HCC) remains poorly characterized. Methods We performed pan-cancer expression and survival analysis using TCGA and GEO databases, validated findings through immunohistochemistry, and conducted functional studies in HCC cell lines using CRISPR-mediated CACUL1 knockout. Transcriptome sequencing, functional assays (CCK-8, wound-healing, transwell invasion), and single-cell RNA-sequencing were performed to elucidate mechanisms. Results Pan-cancer analysis identified CACUL1 overexpression in HCC and gastric cancer (P < 0.001), with prognostic significance in 16 tumor types, including HCC (log-rank P < 0.01). CACUL1 expression independently predicted poor HCC prognosis (multivariable Cox, P < 0.05) and correlated with advanced clinicopathological features and reduced immune checkpoint expression. CACUL1 knockout inhibited HCC cell proliferation and migration but not invasion, with transcriptomic analysis revealing PI3K/AKT signaling pathway enrichment. Co-culture experiments demonstrated that CACUL1 promotes M2 macrophage polarization through Notch1 suppression, with pharmacological Notch inhibition phenocopying this effect. Conclusion CACUL1 functions as a dual-axis oncogenic driver in HCC through enhanced tumor cell proliferation associated with PI3K/AKT signaling and immune evasion via Notch1-dependent macrophage polarization, positioning it as a candidate prognostic biomarker and therapeutic target.
Xing Wang, Yuhan Tan, Ju Wang et al.· Frontiers in Immunology· 0 citations
A novel non-canonical role of TRIM24 as a stabilizer of the p110 CUX1 oncoprotein by recruiting USP10 is revealed, presenting a promising therapeutic target for AML treatment.
Zhiyin Ke, Jie Li, L. Zhong et al.· Journal of Translational Med...· 0 citations
