Abstract 4174: Regulation of metabolic programming in esophageal cancer by transcription factor p63

Abstract Background: Esophageal adenocarcinoma (EAC) and squamous cell carcinoma (ESCC) exhibit markedly different responses to treatment regimens, including chemotherapy, chemoradiation, and immunotherapy. The transcription factor TP63 is expressed in ESCC and notably absent in EAC and is associated with squamous differentiation and expression of the GLUT1 glucose transporter in squamous cell cancers. Given its homology to p53, a known tumor suppressor and regulator of cell metabolism, we sought to determine whether p63 expression may confer a distinct and targetable metabolic program in ESCC relative to EAC. Methods: p63 and GLUT1 expression levels were established in ESCC (TE11, TE14) and EAC (OE19, OE33, and FLO-1) cell lines by immunoblot and qPCR. Associated metabolic programs in EAC vs ESCC cells were assessed using the Seahorse XF bioanalyzer, 2-(N-(7-Nitrobenz-2-oxa-1, 3-diazol-4-yl) Amino)-2-Deoxyglucose (2-NBDG) uptake, and cell viability in the setting glucose deprivation. Genetic knockdown of p63 was performed by siRNA transfection in ESCC cells and resulting effects on mitochondrial metabolism and expression of squamous and glandular differentiation markers were evaluated. The fate of glucose-derived carbon was tracked in ESCC cells with or without genetic knockdown of p63 by incubation with 13C-glucose followed by gas chromatography mass spectrometry and correlated with metabolic gene expression by immunoblot. Results: ESCC cells exhibited higher glycolytic metabolism and glucose uptake and reduced viability in response to glucose starvation, in the setting of increased p63 and GLUT1 expression, relative to EAC cells. ESCC cells also demonstrated lower mitochondrial respiration, intracellular ATP levels, and respiratory spare capacity. Genetic knockdown of p63 in ESCC cells resulted in increased mitochondrial respiration, ATP production, and respiratory spare capacity, as well as reduced sensitivity to glucose deprivation. This was associated with reduced expression of squamous differentiation markers and increased expression of glandular differentiation markers. Furthermore, knockdown of p63 expression increased glucose flux through the tricarboxylic acid (TCA) cycle and towards fatty acid synthesis. This was associated with enhanced pyruvate dehydrogenase activity, and as increased activation of acetyl-CoA carboxylase and fatty acid synthase. Conclusions: Our data suggest that ESCC and EAC represent different metabolic programs, with ESCC more dependent on glucose and glycolytic metabolism and EAC exhibiting greater mitochondrial respiration and respiratory spare capacity. These differences are dependent on transcription factor p63, as loss of p63 in ESCC increased glucose shunting into mitochondrial metabolism and fatty acid synthesis pathways. These data suggest that differential metabolic targeting may be an effective approach for both ESCC and EAC. Citation Format: Niamh McNamee, Keene Abbott, Aya Tal-Mason, Matthew G. Vander Heiden, Uma M. Sachdeva. Regulation of metabolic programming in esophageal cancer by transcription factor p63 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4174.