ABSTRACT
In this study, we investigated the expression of 14-3-3sigma tumor suppressor gene in a panel of NPC cell lines, xenografts and primary tumors. Our objective was to determine the correlation between 14-3-3sigma expression and clinical outcome in NPC. We detected reduced 14-3-3sigma expression in 5/6 NPC tumor lines by quantitative RT-PCR and Western blotting. By immunohistochemical staining, significant down-regulation of 14-3-3sigma was also found in 26/72 (36.1%) primary tumors of NPC patients, who were treated with curative radiotherapy. Promoter methylation was confirmed in a subset of primary tumors by methylation-specific PCR analysis. Importantly, we demonstrated that 14-3-3sigma expression is significantly associated with both overall survival (OS) and cancer-specific survival (CSS), but not with the clinical staging of NPC patients. The low 14-3-3sigma expression was associated with improved overall (p=0.029) and cancer-specific survival (p=0.042) on univariate analysis. 14-3-3sigma expression and staging were also independent variables to all the prognostic factors under multivariate analysis. In conclusion, low expression of 14-3-3sigma appears to be a valuable marker for better survival in patient with NPC. These results provide the evidence that 14-3-3sigma expression is a significant prognostic factor for NPC patients.
Subject(s)
14-3-3 Proteins/biosynthesis , Biomarkers, Tumor/analysis , Carcinoma/metabolism , Exonucleases/biosynthesis , Adult , Aged , Aged, 80 and over , Animals , Biomarkers, Tumor/biosynthesis , Blotting, Western , Carcinoma/mortality , Carcinoma/pathology , DNA Methylation , Exoribonucleases , Female , Gene Expression , Humans , Immunohistochemistry , Kaplan-Meier Estimate , Male , Middle Aged , Nasopharyngeal Carcinoma , Nasopharyngeal Neoplasms/metabolism , Nasopharyngeal Neoplasms/mortality , Nasopharyngeal Neoplasms/pathology , Neoplasm Staging , Prognosis , Promoter Regions, Genetic/genetics , Reverse Transcriptase Polymerase Chain Reaction , Xenograft Model Antitumor Assays , Young AdultABSTRACT
We report an unusual case of ependymoma with pigmentation, a phenomenon that has only been described in a few cases, to our knowledge. This tumor occurred in the fourth ventricle of a 45-year-old man. It showed the typical histologic appearance of ependymoma with perivascular pseudorosettes and rare ependymal rosettes. Some tumor cells contained brown cytoplasmic pigment, which was shown histochemically to represent a mixture of lipofuscin and neuromelanin. The pigment was positive for acid-fast and periodic acid-Schiff stains and was also focally positive for Masson-Fontana and Schmorl stains (bleached by pretreatment with potassium permanganate). In addition, some other tumor cells showed a signet ring morphology as a result of prominent intracytoplasmic vacuolation. Immunohistochemically, all the tumor cells expressed glial fibrillary acidic protein, and rare pigmented tumor cells also expressed HMB-45. Ultrastructural examination showed irregularly shaped heterogeneous electron-dense bodies corresponding to the pigment, and the cytoplasmic vacuoles were formed by dilatation of intracytoplasmic lumens lined by microvilli. Since lipofuscin production can occur in normal ependymal cells and neuromelanin has been suggested to be a melanized form of lipofuscin, it is not surprising that these 2 pigments can be found in ependymoma. In all the previously reported cases, the pigment was shown to represent melanin only. In our case, the HMB-45 positivity in rare tumor cells indicated that there might also be a minor melanin component in the pigment in addition to lipofuscin and neuromelanin.
