Expression And Clinical Significance Of DcR3 In Human Oral Squamous Cell Carcinoma

Objective:Oral squamous cell carcinoma (OSCC), the most common malignant tumor in oral cavity, account for more than 80% of tumors in oral malignant tumor. With the development of clinical treatment, the patients'prognosis has been improved greatly, but the patients'five-year survival rate is still less than 60% in recent years. Decoy receptor 3 (DcR3), a newly identified member of tumor necrosis factor receptor (TNFR) super-family, can reject apoptosis and regulate cell proliferation. It also allow tumor cells to evade immune surveillance and killing. So it might play an important roll in the development of tumor. Many researches discovered that DcR3 was overexpressed in many kinds of malignant tumors. The aim of this study was to detect the expression of DcR3 in OSCC and normal tissues adjacent tumor at the level of protein and mRNA by immunohistochemistry and by in situ hybridization, and then to analyze the relationship between DcR3 and clinicopathological features, such as the degree of differentiation, clinical TNM stage, lymph node metastasis and so on. We also illustrated elementarily the role of DcR3 in carcinogenesis, progression, invasion and metastasis of OSCC. We hope to supply a theoretical evidence for diagnosis, genetic therapy and judgement of prognosis. Methods: specimen and clinicopathological data were obtained from patients with OSCC in the pathological department of affiliated hospital of Lu Zhou Medical College from October 2007 to September 2009. All the specimen were divided into two groups:57 cases of OSCC (24 cases of well differentiated OSCC,19 cases of moderately differentiated and 14 cases of poorly differentiated) and 57 cases of normal tissues adjacent tumor as controls. All cases were diagnosed by veteran pathologist. We applied streptavidin peroxidase immunohistochemistry method to detect DcR3 protein in 57 cases of OSCC and 57 cases of normal tissues adjacent tumor. The relationship between the expression of DcR3 protein and clinicopathological features were analyzed. Using in situ hybridization technique,we also examined the expression of DcR3 mRNA in 57 cases of OSCC and 57 cases of normal tissues adjacent tumor. Statistic analysis was made to figure out the correlation between the expression of DcR3 mRNA and the clinicopathological features. All data were processed by SPSS version.16.0 analysis software. Values of P<0.05 were considered to indicate statistically significant. Results:(1) The positive staining of DcR3 protein located in tumor cytoplasm. The positive rates of expression of DcR3 protein was 56.14%(32/57) in OSCC, and 3.51% (2/57) in normal tissues adjacent tumor. The expression of DcR3 protein in OSCC was significantly higher than normal tissues adjacent tumor (P<0.05). The positive rates of expression of DcR3 protein in well differentiated OSCC was 37.50%(9/24), in moderately differentiated OSCC was 52.63%(10/19) and in poorly differentiated OSCC was 96.85%(13/14). The poorly differentiated OSCC was significantly higher than both the well differentiated OSCC and the moderately differentiated OSCC (P<0.05, P<0.05). But there was no obvious relationship between well differentiated OSCC and moderately differentiated OSCC (P>0.05). The positive rates of expression of DcR3 protein in OSCC in the clinical TNM stageⅢ～Ⅳwas 81.48%(22/27), obviously higher than that in the stageⅠ～Ⅱ33.33%(10/30) (P<0.05). The positive rates of expression of DcR3 protein in the cases with lymph node metastasis was 73.91% (17/23), higher than that in the group without lymph node metastasis 44.11%(15/34) (P<0.05). However, no significant association were observed between DcR3 expression and other clinicopathological features such as sex, age, course of disease, size of tumor and invasion depth (P>0.05). (2) The positive staining of DcR3 mRNA was observed in tumor cytoplasm. The positive rates of expression of DcR3 mRNA was 52.63%(30/57) in OSCC, and was 1.75%(1/57) in normal tissues adjacent tumor. The expression of DcR3 mRNA in OSCC was significantly higher than normal tissues adjacent tumor (P<0.05). The positive rates of expression of DcR3 mRNA in well differentiated OSCC, in moderately differentiated and in poorly differentiated were 37.50% (9/24),47.37%(9/19) and 85.71%(12/14) respectively. The poorly differentiated OSCC was significantly higher than both the well differentiated OSCC and the moderately differentiated OSCC (P<0.05, P<0.05). But there was no relationship between well differentiated OSCC and moderately differentiated OSCC (P>0.05). The positive rates of expression of DcR3 mRNA in OSCC in the clinical TNM stageⅢ～Ⅳwas 70.37%(19/27), obviously higher than that in the stageⅠ～Ⅱ36.67%(11/30) (P<0.05). The positive rates of expression of DcR3 mRNA in the cases with lymph node metastasis was 69.57%(16/23), higher than that in the group without lymph node metastasis 41.18% (14/34) (P<0.05); However, the expression of DcR3 mRNA was not related to other clinicopathological features such as sex, age, course of disease, size of tumor and invasion depth (P>0.05). (3) By consistency checking, the expression of DcR3 protein in 57 cases of OSCC using immunohistochemistry was concordance with DcR3 mRNA using in situ hybridization (P<0.05), and so was in normal tissue adjacent tumor (P<0:05). Conclusion:(1) The expression of DcR3 protein and DcR3 mRNA in OSCC were significantly higher than normal tissues adjacent tumor. It suggested that DcR3 might promote the development of OSCC and all these may be relate to the inhibition of cancer cell apoptosis caused by DcR3. (2) The expression of DcR3 protein and DcR3 mRNA in OSCC were related to the degree of differentiation, clinical TNM stage and lymph node metastasis. These might suggest that the expression of DcR3 might indicate the malignancy of OSCC and be associated with invasion and metastasis of OSCC. (3) Detecting the expression of DcR3 in OSCC is good for evaluating the malignancy and progression of OSCC, so it can assist the clinical comprehensive treatment. (4) The expression of DcR3 protein and mRNA in OSCC were not related to sex, age, course of disease, size of tumor and invasion depth. (5) In paraffin imbedding specimen, concordance results were found in detecting the expression of DcR3 in OSCC by immunohistochemistry and by in situ hybridization. The test for immunohistochemistry technic was simple and the cost was lower. Therefore, making a preliminary dection of DcR3 protein by immunohistochemistry can provide guidance to clinical diagnosis and prognosis of OSCC. (6) If we reduce the expression of DcR3 at the molecular level and induce squamous cell apoptosis, DcR3 might be a new therapeutic target in OSCC.