Key words salivary gland tumors; of p53; vascular endothelial growth factor; immunohistochemistry

 Salivary gland tumors, oral and maxillofacial another class in addition to the odontogenic tumors outside the the characteristic tumor, a large class of diseases that endanger human health, and is still the lack of early clinical indicators to determine the nature of the tumor and the assessment of prognosis. Recent research on the relationship between p53 and VEGF and salivary gland tumors also have some reports, but there are differences. The clinical significance of this study by immunohistochemical methods to detect 54 cases of salivary gland benign and malignant tumors of p53 protein expression of VEGF explore the biological characteristics of both salivary gland tumors and its expression.

    1 Materials and Methods

    1.1 Research Data

    Tissue Source: select the Nanchang University Dental Hospital and the Chinese People’s Liberation ninety-four hospital maxillofacial surgery from 2000 to 2005, 54 cases of surgical removal of the salivary gland tumor tissue before surgery without radiotherapy or chemotherapy, all with complete clinical data. Gender: The 21 males and 33 females. Age Status: 6 to 74 years, with an average age of 45. Histological type: 18 cases of pleomorphic adenoma, mucoepidermoid carcinoma, 18 cases, 18 cases of adenoid cystic carcinoma.

    1.2 Methods

    Using SP immunohistochemical chemical method. Mouse anti-human p53 monoclonal antibody, rabbit anti-human VEGF polyclonal antibody immunohistochemistry SP kit, immunohistochemistry enzyme substrate significantly toner DAB kit were purchased from Beijing Zhongshan Biotechnology Co., Ltd.. Each are equipped with a positive and negative control antibody. Using the known breast cancer tissue sections as positive photo. Instead of primary antibody with PBS buffer as a blank control.

    1.3 The results of judgment

    p53 showed brown nuclear staining positive cells, VEGF brown granules within the cytoplasm or cell membrane positive, counting five random high power field, counting the number of positive cells of 100 cells. Combined with a composite score of staining intensity and percentage of positive cells number. Staining intensity score: Basic uncolored, stained with a similar background to 0; slightly stained, slightly higher than the background for 1 minute; coloring moderate, significantly higher than the background by 2 points; strong dye, coloring dark brown 3 points. 50%为3分。">The percentage of positive cells: no positive staining of tumor cells, ≤ 25% for 1 minute, 26% to 50% 2 50% 3. The two scoring adding 0 to 1 is divided into negative, greater than 2 is divided into a positive immune response; wherein 2 to 3 into (+) greater than 4 is divided into (+).

    1.4 statistical methods

    All data processing using SPSS12.0 statistical software for statistical analysis. Measurement data with the t test, count data using the chi-square test, Fisher exact condition is not met. The bivariate level data analysis using rank correlation analysis. All inspection levels are 0.05.

    2 Results

    2.1 immunohistochemical markers p53 positive signals were mainly located in the nucleus, showing brown particles, non-staining cytoplasm; the VEGF positive signal in the cytoplasm, showing brown particles, as shown in Figure 1 to 5. The different nature of salivary gland tumor VEGF and p53 expression are shown in Table 1. Table 1 shows that pleomorphic adenoma and mucoepidermoid carcinoma, pleomorphic adenoma and adenoid cystic carcinoma p53, VEGF expression difference was statistically significant (P <0.05), mucoepidermoid carcinoma and adenoid cystic 0.05)。">cancer in both the difference was not statistically significant (P> 0.05). Table 1 the different nature of the salivary gland tumors p53, VEGF expression compare Figure 1 adenoid cystic carcinoma p53 expression (SP × 400) Figure 2 mucoepidermoid carcinoma in p53 expression (SP × 400) Figure 3 polymorphonuclear adenomatous positive expression of VEGF (SP × 400) Figure 4 adenoid cystic carcinoma VEGF positive (SP × 400) Figure 5 mucus epidermoid carcinoma of VEGF positive expression (SP × 400)

    2.2 in p53 and VEGF with two salivary gland cancer clinical pathology. 0.05)。">Table 2 shows that different tumor size, tumor of p53, VEGF difference was not statistically significant (P> 0.05). P53, VEGF in the early group (TNM Ⅰ  Ⅱ period) and late (TNM Ⅲ  Ⅳ period) salivary gland cancer, the difference was statistically significant (P <0.05); and in the lymph nodes or distant metastasis group of p53 VEGF expression was significantly higher than those without metastasis (P <0.05). Table 2 two salivary gland cancer, VEGF, p53 and clinicopathological factors.

3 Discussion

    3.1 VEGF expression in salivary gland tumors

    VEGF is generally considered the strongest role in angiogenesis-promoting factor one [1]. VEGF and its family members are essential in tumor angiogenesis and other physiological and pathological angiogenesis inducing factor. The data indicate that in many tumor tissues have higher levels of VEGF expression, and is closely related with prognosis [2,3]. High Shijun [4] that VEGF play an important role in the ACC subtypes, invasion and metastasis, can be used as a clinical relapse prevention, the transfer of a means of detection.

    VEGF in this experiment 54 specimens have different degrees of expression (~ 96%). The experiments show that VEGF expression in adenoid cystic carcinoma and mucoepidermoid carcinoma was significantly higher than pleomorphic adenoma. The two groups of Salivary VEGF expression and tumor location, regardless of the size, lymph node or distant metastasis of VEGF positive group was significantly higher than the negative, TNM staging late group was significantly higher than in the early group. Prompted the high expression of VEGF and salivary gland tumor development are closely related.

    3.2 p53 and salivary gland tumors

    The wild-type and mutant p53 gene existence of wild-type p53 is a tumor suppressor gene, it can cause cell cycle arrest, induction of apoptosis, promote differentiation and reduce the probability of occurrence of mutant cells. The p53 gene is the most commonly mutated gene in human tumors, p53 gene mutation for loss of tumor suppressor function and oncogenic functions obtained. The short half-life of wild-type p53 protein and low levels in normal cells, immunohistochemistry using a general method is difficult to detect. P53 gene mutation, the half-life was significantly prolonged and enhanced stability. Therefore, detection of p53 gene expression in general by immunohistochemical methods and means that the gene mutation [6].

    In recent years, many studies have found that the p53 gene mutation and salivary gland tumors related to the occurrence and development [7,8]. This set of experiments showed that the generally benign salivary gland tumor (pleomorphic adenoma) of p53 expression, two malignancies (adenoid cystic carcinoma, mucoepidermoid carcinoma) of p53 positive expression rate were 50% and 38.9%, higher than the pleomorphic adenoma (P <0.05). The study also revealed that both salivary gland cancer, p53 expression and tumor location, size independent of p53 positive group was significantly higher than the negative group at the regional or distant metastasis, clinical stage late group was significantly higher than in the early group . Prompted high p53 expression in salivary gland tumor development and metastasis (lymph node or distant) is closely related to, and can be used as a reference index to judge the prognosis of salivary gland tumors.

    3.3 p53, VEGF in the relationship of salivary gland tumors

    In this experiment, the expression levels of p53 increased with increased VEGF expression, both showed a significant positive correlation. These results indicate that the mutant p53 expression in the salivary gland tumor angiogenesis process have important synergistic role in VEGF-mediated tumor angiogenesis. Tip p53 gene may modulate angiogenesis through VEGF process. Pal S, et al [9] studies have shown that wild-type p53 forms a complex with the SP  1 transcription factor, to prevent the SP  1 and VEGF promoter binding, thus inhibiting VEGF transcriptional activation, lowered VEGF expression, inhibition of angiogenesis, mutant p53 No such effect. The group of experimental results from immunohistochemical level to support this view. Another study also found no correlation between p53 protein expression and VEGF expression, which is obviously a certain relationship with the selection of cases also prompt tumor angiogenesis in addition to the p53 gene may also have other tumor gene regulation, including some of the original cancer and anti-cancer genes and hormones, growth factors, cytokines, regulation, and the performance of the multiple factors involved in the complex biochemical processes, needs further study to clarify.