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The Serine–Glycine–One-Carbon (SGOC) pathway is pivotal in multiple anabolic processes. Expression levels of SGOC genes are deregulated under tumorigenic conditions, suggesting participation of oncogenes in deregulating the SGOC biosynthetic pathway. However, the underlying mechanism remains elusive. Here, we identified that Interleukin enhancer-binding factor 3 (ILF3) is overexpressed in primary CRC patient specimens and correlates with poor prognosis. ILF3 is critical in regulating the SGOC pathway by directly regulating the mRNA stability of SGOC genes, thereby increasing SGOC genes expression and facilitating tumor growth. Mechanistic studies showed that the EGF–MEK–ERK pathway mediates ILF3 phosphorylation, which hinders E3 ligase speckle-type POZ protein (SPOP)-mediated poly-ubiquitination and degradation of ILF3. Significantly, combination of SGOC inhibitor and the anti-EGFR monoclonal antibody cetuximab can hinder the growth of patient-derived xenografts that sustain high ERK-ILF3 levels. Taken together, deregulation of ILF3 via the EGF–ERK signaling plays an important role in systemic serine metabolic reprogramming and confers a predilection toward CRC development. Our findings indicate that clinical evaluation of SGOC inhibitor is warranted for CRC patients with ILF3 overexpression.

Immune checkpoint blockade therapies are still ineffective for most patients with colorectal cancer (CRC). Immunogenic cell death (ICD) enables the release of key immunostimulatory signals to drive efficient anti-tumor immunity, which could be used to potentiate the effects of immune checkpoint inhibitors. Here, we showed that inhibition of valosin-containing protein (VCP) elicits ICD in CRC. Meanwhile, VCP inhibitor upregulates PD-L1 expression and compromises anti-tumor immunity in vivo. Mechanistically, VCP transcriptionally regulates PD-L1 expression in a JAK1-dependent manner. Combining VCP inhibitor with anti-PD1 remodels tumor immune microenvironment and reduces tumor growth in mouse models of CRC. Addition of oncolytic virus further augments the therapeutic activity of the combination regimen. Our study shows the molecular mechanism for regulating PD-L1 expression by VCP and suggests that inhibition of VCP has the potential to increase the efficacy of immunotherapy in CRC.