Purpose: To identify novel nasopharyngeal carcinoma (NPC) biomarkers by laser capture microdissection and a proteomic approach.
Experimental design: Proteins from pooled microdissected NPC and normal nasopharyngeal epithelial tissues (NNET) were separated by two-dimensional gel electrophoresis, and differential proteins were identified by mass spectrometry. Expression of three differential proteins (stathmin, 14-3-3sigma, and annexin I) in the above two tissues as well as four NPC cell lines was determined by Western blotting. Immunohistochemistry was also done to detect the expression of three differential proteins in 98 cases of primary NPC, 30 cases of NNET, and 20 cases of cervical lymph node metastases, and the correlation of their expression levels with clinicopathologic features and clinical outcomes were evaluated.
Results: Thirty-six differential proteins between the NPC and NNET were identified. The expression levels of stathmin, 14-3-3sigma, and annexin I in the two types of tissues were confirmed and related to differentiation degree and/or metastatic potential of the NPC cell lines. Significant stathmin up-regulation and down-regulation of 14-3-3sigma and annexin I were observed in NPC versus NNET, and significant down-regulation of 14-3-3sigma and annexin I was also observed in lymph node metastasis versus primary NPC. In addition, stathmin up-regulation and down-regulation of 14-3-3sigma and annexin I were significantly correlated with poor histologic differentiation, advanced clinical stage, and recurrence, whereas down-regulation of 14-3-3sigma and annexin I was also significantly correlated with lymph node and distant metastasis. Furthermore, survival curves showed that patients with stathmin up-regulation and down-regulation of 14-3-3sigma and annexin I had a poor prognosis. Multivariate analysis revealed that the expression status of stathmin, 14-3-3sigma, and annexin I was an independent prognostic indicator.
Conclusion: The data suggest that stathmin, 14-3-3sigma, and annexin I are potential biomarkers for the differentiation and prognosis of NPC, and their dysregulation might play an important role in the pathogenesis of NPC.