WNT Oncogenic Transcription Requires MYC Suppression of Lysosomal Activity and EPCAM Stabilization in Gastric Tumors
Patrizia Mulé, Daniel Fernandez-Perez, Simona Amato, Daria Manganaro, Paola Oldani, Stefania Brandini, Giuseppe Diaferia, Alessandro Cuomo, Camilla Recordati, Chiara Soriani, Ambra Dondi, Marika Zanotti, Samantha Rustichelli, Andrea Bisso, Salvatore Pece, Simona Rodighiero, Gioacchino Natoli, Bruno Amati, Karin Johanna Ferrari, Fulvio Chiacchiera, Diego Pasini
Abstract
Background & AimsWNT signaling is central to spatial tissue arrangement and regulating stem cell activity, and it represents the hallmark of gastrointestinal cancers. Although its role in driving intestinal tumors is well characterized, WNT’s role in gastric tumorigenesis remains elusive.MethodsWe have developed mouse models to control the specific expression of an oncogenic form of β-catenin (CTNNB1) in combination with MYC activation in Lgr5+ cells of the gastric antrum. We used multiomics approaches applied in vivo and in organoid models to characterize their cooperation in driving gastric tumorigenesis.ResultsWe report that constitutive β-catenin stabilization in the stomach has negligible oncogenic effects and requires MYC activation to induce gastric tumor formation. Although physiologically low MYC levels in gastric glands limit β-catenin transcriptional activity, increased MYC expression unleashes the WNT oncogenic transcriptional program, promoting β-catenin enhancer invasion without a direct transcriptional cooperation. MYC activation induces a metabolic rewiring that suppresses lysosomal biogenesis through mTOR and ERK activation and MiT/TFE inhibition. This prevents EPCAM degradation by macropinocytosis, promoting β-catenin chromatin accumulation and activation of WNT oncogenic transcription.ConclusionOur results uncovered a new signaling framework with important implications for the control of gastric epithelial architecture and WNT-dependent oncogenic transformation. WNT signaling is central to spatial tissue arrangement and regulating stem cell activity, and it represents the hallmark of gastrointestinal cancers. Although its role in driving intestinal tumors is well characterized, WNT’s role in gastric tumorigenesis remains elusive. We have developed mouse models to control the specific expression of an oncogenic form of β-catenin (CTNNB1) in combination with MYC activation in Lgr5+ cells of the gastric antrum. We used multiomics approaches applied in vivo and in organoid models to characterize their cooperation in driving gastric tumorigenesis. We report that constitutive β-catenin stabilization in the stomach has negligible oncogenic effects and requires MYC activation to induce gastric tumor formation. Although physiologically low MYC levels in gastric glands limit β-catenin transcriptional activity, increased MYC expression unleashes the WNT oncogenic transcriptional program, promoting β-catenin enhancer invasion without a direct transcriptional cooperation. MYC activation induces a metabolic rewiring that suppresses lysosomal biogenesis through mTOR and ERK activation and MiT/TFE inhibition. This prevents EPCAM degradation by macropinocytosis, promoting β-catenin chromatin accumulation and activation of WNT oncogenic transcription. Our results uncovered a new signaling framework with important implications for the control of gastric epithelial architecture and WNT-dependent oncogenic transformation.