e16016 Background: Our prior investigations have demonstrated that PLCE1 actively promotes tumorigenesis, angiogenesis, and cell cycle progression in ESCC. However, the precise role of PLCE1 in glycolysis and its influence on the tumor immune microenvironment (TIME) remain elusive. Methods: To elucidate potential pathways regulated by PLCE1, we applied Affymetrix GeneChip, Affymetrix ClariomD Array, and IP-MS techniques to identify molecules interacting with PLCE1. Subsequently, we validated the involement of PLCE1 in glycolysis through assessments of glycolytic product production in both in vivo and in vitro assays. The underlying mechanisms by which PLCE1 influences glycolysis were further probed through a combination of IP assays, tumor growth experiments, and ubiquitination assays. Next, we conducted multi-color immunofluorescence staining to examine the infiltration of immune cells in human ESCC tissues. We utilized a transgenic PLCE1-/- C57BL/6 mice model to investigate the immune cell distribution in TIME. Results: PLCE1 emerges as a pivotal regulator in glycolytic processes within ESCC cell lines. Knockdown of PLCE1 instigates a notable attenuation of glycolysis, achieved through the modulation of ENO1 expression, a key enzyme in glycolysis. This effect was also observed in vivo. We have elucidated a novel pathway in which PLCE1 orchestrates a reduction in the expression of FBXW7, an E3 ubiquitin ligase, thereby attenuating FBXW7-mediated ubiquitination of ENO1 and fostering ENO1 stability. Based on mutations identified through sequencing of ESCC tissue and drawing from previous studies, we have pinpointed the specific interacting sites between FBXW7 and ENO1. Substrate phosphorylation is necessary for the recognition of FBXW7. We unveil a mechanism wherein PLCE1 interacts with CDK2 to augment ENO1 phosphorylation, potentiating FBXW7 recognition. Nonetheless, CDK2-mediated ENO1 phosphorylation fails to elicit FBXW7-mediated ubiquitination due to limited FBXW7 expression in ESCC. Elevated tumor glycolysis induced by PLCE1 via ENO1 engenders heightened lactate production, thereby dampening cytokine production and CD8+ T cell activation. In human ESCC tissues, a diminished CD8+ T cell population is observed proximal to PLCE1+ENO1+ tumor cells, concomitant with an augmented accumulation of exhausted CD8+ PD1+ T cells in their vicinity. In an ESCC murine model, a more robust infiltration and cytokine production, coupled with diminished PD-1 expression on both CD4+ and CD8+ T cells, is noted in the PLCE1-/- genotype. This effect was particularly prominent upon ENO1 inhibitor administration. Conclusions: Our investigation elucidates that PLCE1 orchestrates the glycolytic pathway in ESCC by upregulating the expression of ENO1, consequently hindering the infiltration and activation of CD8+ T cells, thus fostering an immunosuppressive TIME.
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