Nitidine chloride inhibits colorectal cancer by targeting BUB1: mechanistic insights from molecular dynamics simulation, spatial transcriptomics, and single-cell RNA sequencing
摘要
Colorectal cancer (CRC) is a prevalent malignancy with the efficacy of current treatments limited. Nitidine chloride (NC), a natural alkaloid, exhibits antitumor potential, but its mechanism in CRC remains unclear.
ObjectiveTo investigate the antitumor effects and mechanisms of NC in CRC for clinical therapeutic strategies.
MethodsA Cell Counting Kit-8 was used to assess the viability of HCT116 cells. Xenograft mice received NC (2, 4, 8 mg/kg, intraperitoneal, once every other day for 2 weeks). Transmission electron microscopy and hematoxylin-eosin staining analyzed tumor ultrastructure and pathology. RNA sequencing, real-time quantitative polymerase chain reaction, and molecular dynamics simulation (MDS) examined gene expression and NC-budding uninhibited by benzimidazoles 1 (NC-BUB1) interaction. Single-cell RNA sequencing, spatial transcriptomics, immunohistochemistry, and chromatin immunoprecipitation sequencing explored BUB1 expression and RAD21 regulation. Immune correlation analysis was conducted using TISIDB, TIMER2.0, and deconvolution algorithms (CIBERSORT, CIBERSORT-ABS, EPIC, ESTIMATE, MCPcounter, quanTIseq, TIMER, xCell) to evaluate associations between BUB1 and immune factors or infiltration.
ResultsNC inhibited HCT116 cells with time- and concentration-dependent half-maximal inhibitory concentration reduction. NC-treated tumors displayed apoptosis and reduced angiogenesis. Transcriptomics identified BUB1 as a core downregulated gene. Multi-omics confirmed BUB1 overexpression in CRC (1293 vs. 2299 samples; standardized mean difference = 1.77, area under the curve = 0.94) in proliferative/malignant regions. Immune analyses revealed that high BUB1 expression correlated negatively with antigen presentation molecules, chemokines/receptors, and immune cell infiltration (B cells, M2 macrophages, cancer-associated fibroblasts, endothelial cells), suggesting immune microenvironment suppression. BUB1 knockout inhibited CRC cells; NC reduced BUB1 expression. MDS showed a stable NC-BUB1 complex (− 8.8 kcal/mol). The RAD21–BUB1 axis exerted key regulatory roles.
ConclusionNC exerts anti-CRC effects by downregulating BUB1, disrupting the RAD21–BUB1 axis, and alleviating BUB1-mediated immune suppression.