Olfactomedin-4 in digestive diseases: A mini-review.

Olfactomedin-4 (OLFM4, GW112, hGC-1) is a glycoprotein belonging to the olfactomedin family. The expression of OLFM4 is strong in the small intestine, colon and prostate, and moderate in the stomach and bone marrow. Previous studies have revealed that OLFM4 is closely associated with many digestive diseases. Up-regulation of OLFM4 has been detected in the Helicobacter pylori ( H. pylori )-infected gastric mucosa, inflammatory bowel disease tissue and gastrointestinal malignancies, including gastric cancer, colorectal cancer, pancreatic cancer and gallbladder cancer. Down-regulation of OLFM4 has also been detected in some cases, such as in poorly differentiated, advanced-stage and metastatic tumors. Studies using OLFM4-deficient mouse models have revealed that OLFM4 acts as a negative regulator of H. pylori -specific immune responses and plays an important role in mucosal defense in inflammatory bowel disease. Patients with OLFM4-positive gastric cancer or colorectal cancer have a better survival rate than OLFM4-negative patients. However, the prognosis is worse in pancreatic cancer patients with high levels of expression of OLFM4. The NF-κB, Notch and Wnt signaling pathways are involved in the regulation of OLFM4 expression in digestive diseases, and its role in pathogenesis is associated with anti-inflammation, apoptosis, cell adhesion and proliferation. OLFM4 may serve as a potential specific diagnostic marker and a therapeutic target in digestive diseases. Further studies are required to explore the clinical value of OLFM4.