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Neoplasia. 2006 Sep;8(9):733-46.

Molecular cross-talk between the NFkappaB and STAT3 signaling pathways in head and neck squamous cell carcinoma.

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Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA.


The development of head and neck squamous cell carcinoma (HNSCC) involves the accumulation of genetic and epigenetic alterations in tumor-suppressor proteins, together with the persistent activation of growth-promoting signaling pathways. The activation of epidermal growth factor receptor (EGFR) is a frequent event in HNSCC. However, EGFR-independent mechanisms also contribute to the activation of key intracellular signaling routes, including signal transducer and activator of transcription-3 (STAT3), nuclear factor kappaB (NFkappaB), and Akt. Indeed, the autocrine activation of the gp130 cytokine receptor in HNSCC cells by tumor-released cytokines, such as IL-6, can result in the EGFR-independent activation of STAT3. In this study, we explored the nature of the molecular mechanism underlying enhanced IL-6 secretion in HNSCC cells. We found that HNSCC cells display an increased activity of the IL-6 promoter, which is dependent on the presence of an intact NFkappaB site. Furthermore, NFkappaB inhibition downregulated IL-6 gene and protein expression, and decreased the release of multiple cytokines. Interestingly, interfering with NFkappaB function also prevented the autocrine/paracrine activation of STAT3 in HNSCC cells. These findings demonstrate a cross-talk between the NFkappaB and the STAT3 signaling systems, and support the emerging notion that HNSCC results from the aberrant activity of a signaling network.

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