Expression Of STAT3 And Its Clinical Significance In Thymic Epithelial Tumors

Background& Objective:The thymic epithelial tumors(TET) originates from the thymic epidermis and is the most common mediastinum frontalis tumor in adult.we usually judge its nuture by Masaoka stage and WHO histologic subtype,but this way lacks sensibility for TET sometimes.So it is significant to explore a new biology marker which can discern the tumor nature-optimum or malignant.Nowdays more and more evidence indicates Janus protein tyrosine kinases/Signal transducers and activators of transcription(AKs/STATs) plays a very important role in arising and developing of many tumors.This study investigates the relationship between STAT3 protein expression and recurrence/metastasis and prognosis by immunohistochemical streptavidin peroxidase (SP) methods in 80 cases of thymic epithelial tumors. Methods:The expression of STAT3 protein in TET was detected in 80 cases of TET and 20 cases of paracarcinous normal thymic tissues by immunohistochemical streptavidin peroxidase (SP) methods.Methods:All 60 stageâ… NSCLC tissues and 30 paracarcinous normal lung tissues were obtained from the patients who underwent radical resection and lymph nodes in Provincial Hospital Affiliated to Shandong University. All the 90 specimens were examined by immuno-histochemistry to detect the expression of MTA1 protein. All statistic analyses were performed with SPSS 13.0 statistical software. According to the clinicopathologic factors, the difference of MTA1 protein expression was compared by X2 test. Kaplan-Meier method was performed to calculate the survival rate. Log-rank test was performed to compare the survival difference between the patients with and without MTA1 protein positive expression. Cox regression multivariate analysis was performed to determine independent prognostic factors.Results:(1)The positive expression of STAT3 protein was significantly associated with Masaoka stage (P< 0.05), WHO histologic subtype (P<0.05) while was unrelated with the age, sex, tumor diameter;(2)The recurrence/metastasis Postoperative follow-up observed the rate of recurrence/metastasis in TET patients with STAT3 protein positive expression(35.5%) was significantly higher than those negative expression(4.3%);(3)The 5-year survival rate in patients with positive STAT3 protein expression (61.1%) was significantly lower than that in patients with negative expression (97.7%); (4) The results of Cox multivariate regression analysis indicates STAT3 protein expression was an independent prognostic factor in TET (HR=15.265, P=0.013).Conclusions:The expression of STAT3 protein in TET was detected in 80 cases of TET and 20 cases of paracarcinous normal thymic tissues by immunohistochemical streptavidin peroxidase (SP) methods. There was a significant difference (P<0.05) with the positive expression between tumor tissues(45%) and paracarcinous normal thymic tissues (5%).This indicated the STAT3 protein play a role in the development process, which may be a diagnostic molecular markers of TET. Statistics show that STAT3 protein expression and Masaoka stage(X2=13.742, P<0.05) and WHO histological type (X2=8.623, P<0.05) correlated significantly, STAT3 protein expression rate increased with the malignant degree of TET increased, Suggesting that overexpression of STAT3 may promote thymic tumor cell proliferation, differentiation, and inhibition of apoptosis, and its excessive activation may promote tumor cell formation and development. Statistics show that there is no significant correlation between STAT3 protein expression and sex, age and tumor size.80 patients with TET in this group overall 5-year survival rate was 81.3%, STAT3 protein expression in patients with 5-year survival (61.1%) was significantly lower than the negative expression (97.7%). Postoperative follow-up results, STAT3 protein expression of recurrence/metastasis rate (35.5%) was significantly higher than negative expression (4.3%) and the difference was significant (P<0.05), so we considert STAT3 is the important indicator to determine recurrence/transfer of.tumor. In conclusion, STAT3 is an important prognostic indicator for TET:the positive expression was associated with poor outcome and the negative expression indicated well outcome.So STAT3 has good predictive value as an independent prognostic indicator to determine its recurrence/metastasis in patients with thymic epithelial tumors.