Expression of Claudins in Preneoplastic Conditions of the Gastrointestinal Tract: A Review

SIMPLE SUMMARY: Recent evidence has emerged highlighting the role of claudins in the development of cancers of gastrointestinal organs. Accordingly, studies have further analyzed the role and expression of claudin in preneoplastic gastrointestinal conditions, including Barrett’s esophagus, sessile serrated polyps, inflammatory bowel disease, and others. Several claudins, mainly -1, -2, -3, -4, and -18, have been identified as aberrantly expressed in these conditions. Furthermore, studies have highlighted their prognostic role in patients. Identifying how claudin expression changes in preneoplastic conditions may allow for early diagnosis and treatment. Additionally, it may unlock the door for potential therapeutic molecular targets. ABSTRACT: Premalignant lesions of the gastrointestinal tract are a group of disorders which act as the harbinger of malignant tumors. They are the ground-zero of neoplastic transformation, and their identification and management offer patients the best opportunity of blocking the progress of cancer. However, diagnoses of some of these conditions are hard to make, and their clinical importance is difficult to assess. Recent reports indicated that several claudin proteins have altered expressions in many cancers, including esophageal, gastric, colon, liver, and pancreatic cancers. The early identification of the aberrant expression of these proteins could lead to the early diagnosis and management of gastrointestinal tumors. Specifically, claudins -1, -2, -3, -4, and -18 are frequently overexpressed in gastrointestinal preneoplastic lesions. These altered expressions have shown clinical value in several tumors, providing diagnostic and prognostic information. In this article, we review the literature on the aberrant expression of claudins in preneoplastic lesions of the gastrointestinal tract. Additionally, we summarize their diagnostic and prognostic implications.