RESUMO
Colorectal cancer (CRC) is one of the most common malignant tumors in humans, with liver metastasis being the primary cause of mortality. The epithelial-mesenchymal transition (EMT) process endows cancer cells with enhanced metastatic potential. To elucidate the cellular mechanisms driving EMT in CRC, we analyzed single-cell RNA-sequencing (scRNA-seq) data from 11 non-metastatic primary tumors (TnM) and 11 metastatic primary tumors (TM) from CRC patients. Compared to TnM group, the TM samples showed elevated numbers of malignant epithelial cell and cancer-associated fibroblast (CAF) subsets that displayed enrichments of EMT, angiogenesis, and TGF-ß signaling pathways. One specific TM-enriched subgroup of malignant epithelial cells underwent EMT to trans-differentiate into CXCL1+ CAFs that subsequently differentiated into SFRP2+ CAFs, which was validated by spatial transcriptomic and pseudotime trajectory analyses. Furthermore, cell-cell communication analysis identified BHLHE40 as a probable key transcription factor driving EMT that was associated with poor prognosis. Finally, in vitro and in vivo experiments functionally substantiated that BHLHE40 promoted the proliferation, invasion, migration, EMT, and liver metastasis of CRC cells. In summary, this study identified BHLHE40 as a key transcription factor regulating EMT that promotes liver metastasis in CRC.
RESUMO
BACKGROUND: Recent research has highlighted the versatile functions of long non-coding RNAs (lncRNAs) in the onset and progression of various malignancies. Still, insufficient knowledge is available on how lnc-SOX9-4 functions in colorectal cancer (CRC) progression. METHODS: Bioinformatics analysis was used to identify a novel lncRNA (lnc-SOX9-4), and the expression pattern of the RNA in CRC was verified using qRT-PCR. Gene ontology (GO) term analysis and Gene set enrichment analysis (GSEA) were implemented for the identification of the related mechanisms and roles of lnc-SOX9-4. Immune infiltration analysis was conducted for assessment of how lnc-SOX9-4 is linked to tumor immune cell infiltration level. Both in vitro and in vivo phenotype analyses were conducted for scrutinizing how lnc-SOX9-4 impacts the proliferation and metastasis of CRC. RNA pulldown, mass spectrometry analysis, fluorescent in situ hybridization (FISH), western blotting, and RIP assay aided in verifying lnc-SOX9-4 mechanisms linked to CRC progression. RESULTS: An upregulation of lnc-SOX9-4 was observed in the sample CRC cells and tissues. Elevated lnc-SOX9-4 levels showed a positive association with poor clinical prognosis. Lnc-SOX9-4 was closely correlated to several types of immune infiltrating cells. Functionally, the knockdown of lnc-SOX9-4 significantly inhibited CRC cell proliferation, migration, and invasion abilities. Mechanistically, YBX1 was identified as lnc-SOX9-4, specifically interacting protein in the nucleus. Lnc-SOX9-4 could stabilize YBX1 protein levels by inhibiting poly-ubiquitination and degradation of YBX1. Furthermore, phenotype rescue experiments reveal that lnc-SOX9-4 enhanced the CRC cellular potential to proliferate and metastasize by regulating YBX1 levels. CONCLUSIONS: Lnc-SOX9-4 promoted CRC progression by suppressing cytoplasmic translocation and promoting protein levels of YBX1 can serve as novel treatment targets for diagnosing and treating CRC.