Claudin-7 down-regulation is an important feature in oral squamous cell carcinoma

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Lourenço‚ S.V. ; Coutinho-Camillo‚ C.M. ; Buim‚ M.E.C. ; De Carvalho‚ A.C. ; Lessa‚ R.C. ; Pereira‚ C.M. ; Vettore‚ A.L. ; Carvalho‚ A.L. ; Fregnani‚ J.H. ; Kowalski‚ L.P. ; others

• Document type: Journal article
• Source: Histopathology; v. 57, n. 5, p. 689-698, 2010.

Abstract

Aims: Claudins, a large family of essential tight junction (TJ) proteins, are abnormally regulated in human carcinomas, especially claudin-7. The aim of this study was to investigate claudin-7 expression and alterations in oral squamous cell carcinoma (OSCC). Methods and results: Expression of claudin-7 was analysed in 132 cases of OSCC organized in a tissue microarray. Claudin-7 mRNA transcript was evaluated using real-time polymerase chain reaction and the methylation status of the promoter was also assessed. Claudin-7 was negative in 58.3% of the cases. Loss of claudin-7 protein expression was associated with recurrence (P = 0.019), tumour size (P = 0.014), clinical stage of OSCC (P = 0.055) and disease-free survival (P = 0.015). Down-regulation of the claudin-7 mRNA transcripts was observed in 78% of the cases, in accordance with immunoexpression. Analysis of the methylation status of the promoter region of claudin-7 revealed that treatment of O28 cells (that did not express claudin-7 mRNA transcripts) with 5-Aza-2'-Deoxycytidine (5-Aza-dC) led to the re-expression of claudin-7 mRNA transcript. Conclusion: Loss of claudin-7 expression is associated with important subcellular processes in OSCC with impact on clinical parameters. (AU)

• FAPESP's process: 98/14335-2 - Antonio Prudente Cancer Research Center
• Grantee: Fernando Augusto Soares
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC