Emerging roles of SLC6A14 in digestive system diseases: from amino acid transport to therapeutic targeting.

The solute carrier (SLC) family comprises a large group of membrane transport proteins responsible for the transmembrane transport of nutrients, ions, metabolites, and drugs. SLC6A14 (solute carrier family 6 member 14) is a Na+ and Cl--dependent amino acid transporter with broad substrate specificity, capable of transporting a broad spectrum of neutral and cationic amino acids, thereby supporting cellular nutrient uptake and metabolic homeostasis. Altered expression, genetic variation, or dysregulated function of SLC6A14 has been implicated in inflammatory bowel disease, cystic fibrosis-associated gastrointestinal phenotypes, and several digestive system cancers, including gastric, colorectal, and pancreatic cancers. Dysregulation of SLC6A14 has been implicated in intestinal epithelial injury, regulation of intestinal fluid secretion, and tumor cell proliferation and metastasis. Together, these observations support a broad but context-dependent role for SLC6A14 in digestive system diseases. This review summarizes the transport properties of SLC6A14 and current knowledge of its functions in digestive system diseases, with a focus on its potential as a disease biomarker and therapeutic target.