Characteristic, Regulation and Targeting Strategies of Cancer Stem Cells and Their Niche in Digestive System Tumors

ABSTRACT Digestive system tumor, including esophageal tumor, gastric tumor, intestinal tumor, liver tumor, pancreatic tumor, and cholangiocarcinoma, are the most common tumors worldwide and serve as a major cause of tumor‐related death. Cancer stem cells (CSCs) are a small group of cells in tumors that harbor self‐renewal, differentiation abilities, playing a crucial role in tumor initiation, progression, metastasis, and are supposed to be the fundamental cause of tumor recurrence after conventional treatment. A comprehensive understanding and targeting of CSCs is the key to overcoming tumors. In this review, focusing on digestive system tumors, we summarize the characteristics of CSCs, review the intracellular mechanisms that regulate self‐renewal and functional maintenance of CSCs, including stemness pathways, transcription and epigenetic regulation, metabolic regulation, and noncoding RNAs, and demonstrate microenvironmental regulation and systemic regulation of CSCs at molecular and cellular levels. Finally, we summarize recent advances in tumor therapy with CSC targeting and their niche remodeling. These research progress on CSCs in digestive system tumors provide crucial insights into the occurrence, development, drug resistance, recurrence and metastasis of tumors, and offers new targeted treatment strategies for defeating tumors.