<p>The Wnt/β-catenin pathway is strongly relevant to pancreatic cancer progression, poor prognostic outcomes, and elevated cancer-related mortality. However, the mechanism underlying continuously activated Wnt/β-catenin signaling in pancreatic cancer, a context in which adenomatous polyposis coli (APC) mutations are rarely observed, remains poorly understood. In this study, we investigated the role of STYK1 in regulating canonical Wnt/β-catenin signaling and pancreatic cancer tumorigenesis using the <i>LSL-Kras</i><sup><i>G12D</i></sup>; <i>Trp53</i><sup><i>R172H/+</i></sup>; <i>Pdx1</i><sup><i>Cre</i></sup> mouse model. Our findings demonstrate that STYK1 directly binds to β-catenin and GSK3β, inhibiting GSK3β activity by increasing the level of its kinase-inactive form, which is phosphorylated at S9, and promoting its sequestration into MVBs. We further showed that STYK1-mediated GSK3β sequestration is impaired by autophagy inhibitors or in ATG7 knockout cells, linking this process to autophagic regulation. Structural analysis identified conserved tyrosine-based (Y191QRL194) and dileucine-based (GDLL203-204) sorting motifs in STYK1, which facilitate clathrin/AP2-dependent internalization essential for GSK3β sequestration. The phosphorylation of STYK1 at Y191 by BLK kinase enhances its interaction with AP2, thereby accelerating GSK3β sequestration and subsequent Wnt/β-catenin pathway activation. Notably, inhibitory peptides targeting either the STYK1-β-catenin or the STYK1-GSK3β interface significantly suppressed pancreatic cancer development in vitro and in vivo, underscoring their therapeutic potential. Collectively, these results elucidate a novel STYK1-driven mechanism for Wnt/β-catenin activation in APC-independent pancreatic cancer and provide preclinical evidence for targeting STYK1-mediated signaling as a therapeutic strategy.</p>

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Serine/threonine/tyrosine kinase 1 drives pancreatic carcinogenesis via GSK3β sequestration-mediated Wnt/β-catenin pathway hyperactivation

  • Cefan Zhou,
  • Xueying Dong,
  • Shi Li,
  • Yue Xi,
  • Yuan Liu,
  • Xuehong Qian,
  • Ziyan Song,
  • Li Zhou,
  • Rui Zhang,
  • Hao Lyu,
  • Shuai Xiao,
  • Dong Guo,
  • Qi Zhang,
  • Weiyong Liu,
  • Yan Xiong,
  • Zhentian Wang,
  • Chaojun Yan,
  • Zijian Zhang,
  • Haichuan Zhu,
  • Xing-Zhen Chen,
  • Zhiyin Song,
  • Jingfeng Tang

摘要

The Wnt/β-catenin pathway is strongly relevant to pancreatic cancer progression, poor prognostic outcomes, and elevated cancer-related mortality. However, the mechanism underlying continuously activated Wnt/β-catenin signaling in pancreatic cancer, a context in which adenomatous polyposis coli (APC) mutations are rarely observed, remains poorly understood. In this study, we investigated the role of STYK1 in regulating canonical Wnt/β-catenin signaling and pancreatic cancer tumorigenesis using the LSL-KrasG12D; Trp53R172H/+; Pdx1Cre mouse model. Our findings demonstrate that STYK1 directly binds to β-catenin and GSK3β, inhibiting GSK3β activity by increasing the level of its kinase-inactive form, which is phosphorylated at S9, and promoting its sequestration into MVBs. We further showed that STYK1-mediated GSK3β sequestration is impaired by autophagy inhibitors or in ATG7 knockout cells, linking this process to autophagic regulation. Structural analysis identified conserved tyrosine-based (Y191QRL194) and dileucine-based (GDLL203-204) sorting motifs in STYK1, which facilitate clathrin/AP2-dependent internalization essential for GSK3β sequestration. The phosphorylation of STYK1 at Y191 by BLK kinase enhances its interaction with AP2, thereby accelerating GSK3β sequestration and subsequent Wnt/β-catenin pathway activation. Notably, inhibitory peptides targeting either the STYK1-β-catenin or the STYK1-GSK3β interface significantly suppressed pancreatic cancer development in vitro and in vivo, underscoring their therapeutic potential. Collectively, these results elucidate a novel STYK1-driven mechanism for Wnt/β-catenin activation in APC-independent pancreatic cancer and provide preclinical evidence for targeting STYK1-mediated signaling as a therapeutic strategy.