Wnt Signaling and Circular RNAs in Esophageal and Gastric Cancers: Opportunities for Early Detection and Targeted Therapy.

Aberrant activation of Wnt/β-catenin signaling, frequently caused by oncogenic mutations, plays a crucial role in the development, progression, and therapy resistance of gastric, esophageal, hepatic, pancreatic, and colorectal cancers. Concurrently, circular RNAs (circRNAs), produced by back-splicing of precursor mRNAs (pre-mRNAs), have emerged as critical modulators of this pathway. Accumulating evidence indicates that specific circRNAs regulate Wnt/β-catenin signaling by sponging microRNAs, interacting with RNA-binding proteins, modulating protein function, and altering the expression of pathway components. Some circRNAs are also subject to feedback regulation by Wnt signaling itself. Clinically, tumor-associated circRNAs are present in body fluids and correlate with disease stage, metastatic burden, and patient survival, underscoring their potential as early and minimally invasive biomarkers. Moreover, targeting oncogenic circRNAs has shown promise in preclinical models of Wnt-driven gastrointestinal malignancies. In this review, we summarize the current understanding of the interplay between circRNAs and Wnt/β-catenin signaling in gastric and esophageal cancers. We discuss the translational challenges and emerging opportunities for biomarker development and targeted therapy.