| Context:Nasopharyngeal carcinoma (NPC) is a malignant tumor originating in the nasopharynx, it differs overwhelmingly from other tumors of the head and neck in its causes, occurrence, progression, and treatment. It is vastly more common in southern regions of China than elsewhere. The pathogenesis of nasopharyngeal carcinoma is a complicated process principally involving genetic predisposition, Epstein-Bar Virus infection and environmental factors etc.. However, there are many specific pathogenesis are unclear. Osteopontin (OPN) is a considerable and multifunctional extracellular matrix phosphoglycoprote-in. Recent studies have shown that OPN is overexpressed in a variety of cancers, including lung cancer, breast cancer, colorectal cancer, stomach cancer, ovarian cancer, melanoma and mesothelioma and so on. The fact that it interacts with multiple cell surface receptors which are ubiquitously expressed makes it an active player in many physiological and pathological processes, mainly involving the malignant transformation, invasion, metastasis and development etc. of many kinds of cancers. Even someone posed that OPN can be regarded as a target for molecular targeted therapy of many kinds of tumors. By now the expression of OPN in tumor tissue of NPC and its significance remain to be elucidated.Purpose:To investigate the expression situation of OPN in NPC tissue specimens and approach its significance in NPC; to provide reference index and academic basis for the early diagnosis and clinical treatment of NPC.Experimental Design, Material and Methods:Cross-sectional studies were conducted involving nasopharyngeal carcinoma, chronic nasopharyngitis and adjacent non-cancerous tissues. Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to measure messenger RNA of OPN relative expression in fresh frigorific tissues and messenger RNA content was quantitatively determined by image analysis technique; the extent, intensity and localization of OPN expression in paraffin-embedded tissue sections were evaluated with immunohistochemistry (IHC). The relationships of OPN mRNA and OPN protein expression to clinical and pathologic parameters of NPC patients were statistically analyzed. We also used western blotting to (WB) detect the expression situation of OPN protein in 12 pairs cancerous and adjacent non-cancerous tissues paired samples.Results:From the results of semi-quantitative RT-PCR we obtained the mean (±standard deviation) (x±SD) for OPN/GAPDH(mRNA gray scale value) for OPN expression in 44 nasopharyngeal carcinoma tissues is 0.80 (±0.24) compared with 0.32 (±0.18) in 15 chronic nasopharyngitis. There was statistical significance between them (P<0.05). IHC showed that the staining of OPN was mainly located in the cytoplasm of tumor cells. The positive ratio of OPN in the tissue samples from 67 patients with nasopharyngeal carcinoma (88.1%) significantly higher the one in 21 cases chronic nasopharyngitis (28.6%) (P<0.05). Statistical analyses of the two results above displayed the expression of both OPN mRNA and OPN had nothing to do with age and sex (P>0.05), but associated with T, N and clinical stages of NPC (P<0.05). Osteopontin levels in cancerous tissues were higher than those in corresponding adjacent non-cancerous tissues and the means of OPN/β-Actin (gray scale value) are 0.83 (±0.16) vs0.51 (±0.21).There was significant difference (P<0.05).Conclusions:The results in our studies suggested that OPN mRNA and OPN protein were overexpressed in NPC. We supposed they may be involved in the malignant transformation of NPC.The strong correlation between OPN mRNA and OPN protein expression and pathological parameters of NPC indicated OPN may play a part in the invasion, metastasis and progression of NPC.
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