Low expression of Sp100 in laryngeal cancer: correlation with cell differentiation.

BACKGROUND: Sp100 is a permanent ProMyelocytic Leukaemian nuclear bodies (PML NB)-associated protein, and has been reported to participate in the regulation of transcriptional activity, apoptosis and other cellular biological processes. The aim of the present study was to explore the expression of Sp100 and its potential clinical implications in laryngeal cancer. MATERIAL/METHODS: The mRNA and protein levels of Sp100 in 96 laryngeal cancer samples and paired normal epithelium were examined by RT-PCR, Western blot and immuno-histochemical staining. The correlation of Sp100 expression with clinicopathological features of these patients was assessed by Chi-squared test. RESULTS: The coherent low Sp100 expression of both transcriptional and translational levels were confirmed in the malignant tissues compared to the normal mucosa, and the expression was down-regulated among the well-, moderately- and poorly-differentiated cancer cells accordingly. Moreover, immuno-histochemical staining demonstrated that Sp100 showed a predominantly nuclear pattern in well-differentiated cancer cells, and diffuse cellular distribution in cytoplasm in poorly-differentiated cancer cells. Besides histological type of cancer cells, other clinicopathological characteristics, including age, sex, T classification, lymph node metastasis, distant metastasis and clinical stage, showed no significant correlation with Sp100 low expression. CONCLUSIONS: Our finding provides an important clue to further understanding the role of Sp100 in the initiation and progression of tumorgenesis.