| IntroductionGastric cancer is one of the most common malignancies worldwide that threatens human health. The main reason that influences the prognosis of gastric carcinoma is the early diagnosis of gastric cancer. On the other hand the patients who are treated by operation are also dead because of the metastases of important visceras. At present, it is an effective way to discover gastric cancer by gastroscopy, but there is some deficit for spread examination, so it is important to find a simple sensitive and specific method to diagnose early stomach cancer. Cell signal transduction includes direct signal transduction and indirect singnal transduction. Transmembrane signal transduction is made up of three parts:membrane receptor, signal transduction system in cells and effectors. Research expressed surviving could be next genes signal transduction pathways of stat3.STATs (single transductors and activators of transcription), are a kind of DNA combined proteins, being made up of 750-850 amino acids. Stat family in mammals includes STAT1 (α/β), STAT2, STAT3 (α/β/γ), STAT4, STAT5 (a/b), STAT6. JAK-STATs are basic molecules to react to some cell factors, such as IFN, IL, forming the classic signal transduction pathay:JAK-STAT pathway. STAT3 expressed in various kinds of cells and tissues, participating in cell growth, malignant transformation, apoptosis. Lately, many studies have proved that STAT3 was associated with CNS diseases, tumor, cardiovascular diseases. Cytokines activate Jauns kinase, which phosphorylate and activate STAT. When STAT was activated, it translocated into nucleus in the form of dimers. STAT combines specific DNA in promoter region in genes and takes effect. Other studies suggested that intracellular stimulus could activate STAT and other oncogenes, such as Eyk, Bmx, V-abl and could activate JAK-STAT transduction pathway, and then activate signal transduction of cytokines, promoting cell differentiation. Other studies suggested that STAT was associated with tumors. In a lot of cancer tissues and tumor cell lines, activated STATs, especially STAT3, can be founded. The abnormally activated STAT3 can promote cell differentiation and increasement, and inhibit cell apoptosis, leading to tumor cell generation and development and chemotherapy resisting cell lines. Survivin was new inhibiter of apoptosis family.ObjectiveIn this study we employed immunohischemical methed to detect stat3, p-stat3 and survivin protein expression in human gastric carcinoma and precancerous lesions. The correlation among stat3, p-stat3 and survivin was analyzed objectively. Furthermore, the correlation and significance with clinicopathological features of gastric carcinoma have been explored.Material and methodsClinical material:Ninety-one cases of surgically resected gastric carcinoma specimens and matched normal gastric mucosa,35 cases of intestinal metaplasia (IM) as well as 7cases of dysplasia (DYS), were collectted from the first Affiliated Hospital of China Medical University from August 2006 to May 2008. The age of the patients ranges from 30 to 80 years old. According to WHO's histological classification of gastric cancer, the cases were classified as 2 cases of papillary adenocarcinoma (papi ade),8 well-differentiated adenocarcinoma (well ade),27 moderately-differentiated adencarcinoma (mod ade),32 poorly-differentiated adenocarcinoma (poor ade),14 mucinous adenocarcinoma (mucin ade),4 signet ring cell carcinoma (SRC) and 2 undifferentiated adenocarcinoma (undiff ade). The samples were fixed in 10% formalin, embedded in paraffin, cut into 4μm-thick sections and constructed in four blocks of tissue microarray (TMA). All the specimens were diagnosed by two experienced pathologists.Constructing gastric cancer tissue chip:Tissue chips were made by tissue chip maker (Miroarrayer, Beecher Instruments, USA). Four TMA blocks numbered 1 to 4 contain gastric cancer and precancerous lesions were constructed. The TMA blocks were cut continuously and all sections were cut within 4μm. Sections for immunohistochemical stain were fixed on the slides processed by 0.1% polylysine to prevent slipping. Sections were baked in 60℃for 1 hour, and then continued baking in 60℃for 18 hours. After baking, the sections were kept in room temperature for further use.Immunohistochemical staining for STAT3, p-STAT3 and Survivin protein expression:Tissue chips of gastric cancer and precancerous lesions were immunohistochemical stained by Envision method. Imimmuno-Bridge kits rabbit anti-human stat3, p-stat3 monoclonal antibody (working dilution 1:120,1:30) and rabbit anti-human survivin polyclonal antibody were bought from CST and SAB inc. (USA), Fujian Maixin company in China and Beijing jinqiao biothchnique limited company. All steps were accomplished in accordance with the instructions. PBS used instead of specific antibodies for negative control.Evaluation of immunostaining results:Two hundred cells from two selected representative fields of each sample were counted by two independent observers. The staining intensity was classified as 0 (negative),1 (weak),2 (moderate), and 3 (strong). Positive cells were half quantified as a percentage of the total number of the same kind of cells counted in 2 high power field (×400), and assigned to one of five categories:0: <5%,1:5～25%,2:26～50%,3:51～75% and 4:>75%. According to the product of intensity of immunostaining and percentage of positive cells, immunostaining results were divided into:negative (-),0; weakly positive (+),1～4; moderately positive (++), 5～8; strongly positive (+++),9～12.Statistical analysis:The data was processed using SPSS 11.5 statistical software. Quantitative date was expressed with mean-standard deviation. Data were analyzed by Fisher's exactχ2 test, independent-samples t-test and Kendall's tau-b rank related test. P values less than 0.05 were considered to be statistically significant.ResultsThe positive rates of STAT3 and p-STAT3 and Survivin expression were significantly higher in intestinal metaplasia (95.2%,71.4%,91.4%), dysplasia(85.7%, 100%,100%) and gastric carcinoma (67.0%,60.0%,81.32%)than in normal gastric mucosa (6.6%,32%,3.9%), P<0.05; In gastric cancer with lymph node metastasis, the positive rate of STAT3 and p-STAT3 protein(67.7%,69.4%) was significantly higher than that in the group without lymph node metastasis(65.2%,35.7%), P<0.05. In gastric carcinoma STAT3 expression was positively correlated with p-STAT3 expression (rk=0.288, P=0.013). The positive rates of p-STAT3 and Survivin expression were significantly higher in intestinal metaplasia (71.4%,91.4%), dysplasia(100%,100%) and gastric carcinoma (60.0%,81.32%)than in normal gastric mucosa (32%,3.9%), P<0.05. In gastric cancer with lymph node metastasis, the positive rate of p-STAT3 and Survivin protein(69.4%,86.8%) was significantly higher than that in the group without lymph node metastasis(35.7%,65.2%),P<0.05. There was a close relationship between the STAT3, p-STAT3 and Survivin expression in gastric carcinomas and lymph metastasis, P<0.05, but not gender, age, Borrmann's classification, Lauren types or WHO histological types.Conclusion1. The up-regulation of STAT3 may play important roles in the occurrence, progression, invasion and metastasis of gastric cancer. p-STAT3 as activated pattern is closely related to lymph metastasis which represents malignant biological essence of gastric cancer. The result of this study indicated that STAT3 and p-STAT3 may be markers of value in gastric cancer diagnosis and treatment, but the specific molecular pathological mechanism still require further investigation.2. Survivin is a new member of apoptosis inhibiting proteins family and an important factor that contacts cell cycle and apoptosis. This study indicated Survivin participated in the gastric mucosa canceration. Survivin may serve as a clinical application of value protein marker for the early diagnosis and early warning for canceration of gastric mucosa. The result also indicated that Survivin is hoped to be the indicator in judging poor prognosis of gastric cancer. |
PDF Full Text Request