Zeta’s recombinant rabbit monoclonal antibody binds Claudin 18.2, a tight junction protein that may have a prognostic role in diagnosis of gastric and esophagogastric adenocarcinomas.
The tight junction protein Claudin 18.2 is significantly overexpressed in gastric adenocarcinomas (GC). Clinical studies observed Claudin 18.2 overexpression in 46.5% of patients throughout the stages I-III of gastric adenocarcinoma while parental Claudin 18 overexpression was found in 22.5% primary cases and 25% metastatic cases of esophagogastric adenocarcinomas. Claudin 18.2 overexpression was observed in 51.1% of patients stage I, 47.9% of patients stage II, and 41.6% of patients stage III with gastric cancer. In addition to GC, Claudin 18.2 overexpression was observed in breast cancer, colon cancer, liver cancer, head and neck cancer, and bronchial cancer. Moreover, Claudin 18.2 was demonstrated to contribute to proliferation, differentiation, and migration of cancer cells.
The claudin superfamily consists of many structurally related proteins in humans. These proteins are important structural and functional components of tight junctions in paracellular transport. Claudins are located in epithelial and endothelial cells in all tight junction-bearing tissues. Three classes of proteins are known to localize to tight junctions, including the claudins, occluding, and junction adhesion molecules. Claudins, which consist of four transmembrane domains and two extracellular loops, make up tight junction strands. Emerging evidence suggests that the claudin family of proteins regulates transport through tight junctions via differential discrimination for solute size and charge. Claudin expression is often highly restricted to specific regions of different tissues and may have an important role in transcellular transport through tight junctions. Claudin 18 isoform expression is typically restricted to stomach (wildtype), pulmonary tissues (Claudin 18.1), and gastric tissues (Claudin 18.2) reducing the risk of isoform cross presentation.
The human isoform Claudin 18.2 differs from parental wt-Claudin 18 in the first 69 N-terminal amino acids only, hence the Zeta antibody to Claudin 18.2 maps to the extracellular loop ECL1.
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