Differences in the expression profiles of claudin proteins in human gastric carcinoma compared with non‑neoplastic mucosa.

Numerous genetic alterations associated with cancer progression have the potential to serve as biomarkers for the early diagnosis of cancer. Numerous studies have suggested that claudin proteins, which are the primary components of tight junction structures, are associated with the regulation of cell polarity and cell differentiation. To investigate the expression profiles of the tight junction proteins claudin-2, -5, -7 and -8 in gastric carcinoma, immunohistochemical analysis, western blotting and reverse transcription-quantitative polymerase chain reaction analysis was used to detect the expression profiles of these claudin proteins in gastric carcinoma tissues and in homologous non-neoplastic mucosal tissues. According to the present study, the expression levels of claudin-7 and claudin-8 were downregulated, while the expression of claudin-5 was upregulated in gastric carcinoma tissues compared with in non-neoplastic mucosal tissues. Additionally, no notable difference was observed between claudin-2 expression in gastric carcinoma tissues and non-neoplastic mucosae. Correlations between claudin-7 and -8 expression and lymphatic metastasis in gastric carcinoma tissues were additionally reported. In summary, the present study revealed the distinct expression profiles of claudin-5, -7 and -8 in non-neoplastic mucosal tissues and gastric carcinoma tissues. Furthermore, the expression of these claudin proteins was highly associated with metastatic progression and prognosis in patients with gastric carcinoma, and had predictive value for the metastasis and survival of patients with gastric carcinoma.