172P - PLCE1 stabilizes ENO1 to enhance glycolysis in esophageal squamous cell carcinoma (ESCC) and induces an immune-suppressive tumor microenvironment

Background

PLCE1 has been identified as a susceptibility gene for ESCC. However, the precise involvement of PLCE1 in glycolysis and its impact on anti-tumor immunity remain elusive.

Methods

We conducted an analysis of DEG) in ESCC cell lines following the silencing of PLCE1 using Affymetrix GeneChip technology. We employed IP-MS to identify molecules interacting with PLCE1, which are also associated with glycolytic processes. The mechanisms were further probed through a combination of IP assays, in vivo tumor growth experiments, and ubiquitination assays. To study the role of PLCE1 in glycolysis and its impact on anti-tumor immunity, we established an ESCC-induced model in C57BL/6 mice with the PLCE1^-/- genotype, utilizing the carcinogen 4NQO.

Results

Bioinformatics analysis revealed that DEGs were significantly enriched in cell metabolism, particularly the glycolysis pathway. Knockdown of PLCE1 led to the suppression of glycolysis in ESCC cell lines through the regulation of ENO1 expression, a key enzyme in glycolysis. This effect was observed both in vitro and in vivo. Additionally, we have elucidated a novel pathway in which PLCE1 interacted with CDK2 and ENO1 to enhance the phosphorylation and stability of ENO1. Phosphorylation of ENO1 effectively prevented its ubiquitination and proteasome-mediated degradation, which was orchestrated by FBXW7-a recognized E3 ubiquitin ligase. In human ESCC tissues, we observed an increase in the population of CD8⁺ T cells in close proximity to PLCE1⁺ENO1⁺ tumor cells. A heightened accumulation of CD8⁺ PD1⁺ T cells was noted around these PLCE1⁺ENO1⁺ tumor cells. In an ESCC-induced mice model, a more pronounced infiltration of both CD4⁺ T cells and CD8⁺ T cells was observed in the PLCE1^-/- genotype. Notably, T cells within the PLCE1^-/- genotype exhibited heightened cytokine production and lower PD1 expression, an effect that was further potentiated by the ENO1 inhibitor.

Conclusions

Our study demonstrates that PLCE1 has the capacity to interact with CDK2 and ENO1, thereby counteracting FBXW7-mediated ubiquitination of ENO1. This intricate mechanism leads to an augmentation of glycolysis in ESCC and fosters an immune-suppressive tumor microenvironment.

Legal entity responsible for the study

The authors.

Funding

Natural Science Foundation of China.

Disclosure

All authors have declared no conflicts of interest.