Claudins proteins in brain tumors

Tight junctions (TJs) are essential for preserving cell polarity and controlling permeability. It has been disclosed that TJ proteins, especially specific claudins (CLDNs), are linked to inflammation and contribute to the emergence of diverse cancers, including brain malignancies. Aggressive gliomas, including glioblastoma multiforme (GBM), remain among the most common and deadly central nervous system (CNS) tumors worldwide, despite considerable advances in diagnostic and therapeutic approaches. These types of tumors are characterized by high rates of recurrence and metastasis, resulting in poor outcomes and prognosis. The pathophysiology of brain cancer is closely linked to CLDNs, as these specific proteins play critical roles in tumor cell proliferation, invasion, and disruption of the blood-brain barrier (BBB). Some studies reported the potential role of CLDNs in glioma progression and other neurological disorders. The purpose of this review is to highlight the significance of CLDNs in CNS tumors, especially their participation in the formation of malignant gliomas. Additionally, the diagnostic and prognostic importance of selected CLDNs has been assessed. Selected CLDNs, such as CLDN3 and CLDN4 promote GBM growth, proliferation and migration. Moreover, overexpression of CLDN3 support progression and metastasis of these malignancies, while reduced expression of CLDN1 and CLDN5 is observed in advanced gliomas. Presented results suggest that CLDNs may serve as biomarkers for diagnosis and prognosis as well as therapeutic targets in CNS tumors. Further investigation is essential to clarify their clinical relevance and therapeutic potential.