Metastasis accounts for more than 90% of cancer-related mortality, and thus, there is a compelling need for innovative therapeutic breakthroughs. TP53 mutations are detected in up to 80% of esophageal squamous cell carcinomas (ESCCs), the major subtype of esophageal cancer and one of the most lethal cancers worldwide, as well as in other SCCs. These mutations in turn correlate with poor patient prognosis and high metastatic rates.
To elucidate novel mutant p53-dependent mechanisms in promoting ESCC metastasis, we generated a mouse model combining genetic and carcinogenic approaches: We treated the L2-Cre (esophageal specific promoter); LSL-Trp53R172H/-, Trp53-/- or Trp53+/+; Rosa26LSL-YFP mice with a carcinogen 4-NQO, and isolated primary and metastatic tumor cells that vary in their p53 statuses.
We have shown that ESCC cells with Trp53R172H exhibit greater metastatic capabilities compared to the tumor cells harboring Trp53-/-, indicating gain-of-function (GOF) activity. Through comprehensive RNA-seq and cytokine array analyses, we identified that Colony-stimulating factor-1 (Csf-1) is significantly upregulated in a p53-R172H-dependent manner in metastatic lung lesions of ESCC. p53-R172H binds to the promoter region of Csf-1 locus in metastatic ESCC cells.
Our findings demonstrate that p53-R172H-dependent Csf-1 signaling through its cognate receptor Csf-1r enhances tumor cell invasion and lung metastasis by utilizing complementary genetic and pharmacological approaches. This mechanism is mediated in part through Stat3 phosphorylation and epithelial-to-mesenchymal transition (EMT). These findings are further supported through in vivo targeting of Csf-1r. In addition, high levels of CSF-1 also correlate with mutant p53 in ESCC Tissue Microarrays (TMAs) and The Cancer Genome Atlas (TCGA) datasets.
Our CUT&RUN-seq analysis on ESCC tumor cells revealed that both the Csf-1 locus and EMT-associated genes are enriched with histone 3 lysine 27 acetylation (H3K27ac). This enrichment creates a permissive environment for the interaction between Brd4 and p53-R172H, thereby regulating Csf-1 transcription. Notably, Brd4 interacts specifically with p53-R172H. Inhibiting Brd4 not only decreases tumor invasion and lung metastasis, but also reduces circulating Csf-1 levels in blood serum in vivo.
Overall, our results establish a novel p53-R172H-dependent Brd4-Csf-1 signaling axis that facilitates lung metastasis in ESCC and underscores the GOF properties of p53-R172H. Our discoveries identify therapeutic vulnerabilities in metastatic ESCC, which can be applicable to other SCCs with similar transcriptomic and epigenetic profiles. These insights pave the way for developing therapeutic strategies for this difficult-to-treat disease.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/w1ga-bb52 |
| Date | January 2024 |
| Creators | Efe, Gizem |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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