Article
Aberrant Methylation of SOCS-3 in Head and Neck Carcinomas and its precursor lesions: a new therapeutic approach?
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Published: | September 22, 2005 |
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Aims: This study was performed to elucidate the role of Suppressor of Cytokine Signaling (SOCS)-3 in the tumorigenesis of squamous cell carcinoma of the head and neck (HNSCC) and its precursor lesions.
Methods: After microdissection, promoter methylation of SOCS-3 was studied by using methylation-specific PCR in 94 HNSCC, corresponding normal mucosa, lymph node metastases and 16 high and 21 low grade dysplasias. The presence of SOCS-3 mRNA transcripts was confirmed by semiquantitative real-time PCR, and the SOCS-3 protein was analyzed immunohistochemically.
Results: SOCS-3 hypermethylation was found in 85/94 HNSCC (90%) and in 10/16 high and 9/21 low grade dysplasias. Lymph node metastases exhibited an identical methylation status as the primary tumors. In the cell lines tested, SOCS-3 transcripts increased upon treatment with the demethylation compound 5-aza-2-deoxycytidine. Overexpression of wild type SOCS-3 in carcinoma cells with methylated SOCS-3 resulted in the induction of apoptosis and growth suppression as well as downregulation of STAT3, bcl-2 as well as bcl-x.
Conclusions: Our data suggest, that promoter methylation of SOCS-3 is involved in the carcinogenesis of HNSCC. Due to its involvement in tumor growth, restoration of SOCS-3 may hold treatment potential for HNSCC.