The Expression Of STAT3 In Human Thyroid Carcinoma And Effects Of Its Specific SiRNA On Cell Proliferation And Invasion

OBJECTIVE:In this study, we first examined the expression of STAT3 in thyroid carcinoma and its relationship with clinicopathological characteristics. Then we investigated the effect of proliferation and invasion in human thyroid carcinoma cell line SW579 after the STAT3 gene silencing. Thus may offer a reference for the clinical diagnosis and prognosis of thyroid tumors, and provide a novel target in gene therapy.METHODS:45 papillary thyroid cancer tissues,15 thyroid adenoma tissues and 15 normal thyroid tissue was collected in Pathology department of the union hospital affiliated of Fujian Medical University in 2007, and the expression in protein level of STAT3 and VEGF-C was detected by immunehistochemistry. The expression of STAT3 and VEGF-C was analyzed with the relationship between thyroid cancer, Respectively.Specific STAT3 siRNA was synthesized by transcription in vitro; The role STAT3 plays in the growth of thyroid cancer cells which were transfected by siRNA through oligofectamine was detected by Methyl Thiazolyl Tetrazolium (MTT) assay; The expression of MMP2 and MMP9 mRNA in SW579 which was transfected 72 hours was tested by RT-PCR; invasion capacity in vitro of cells was tested by TranswellInvasion Chamber.RESULTS:In normal thyroid tissue, thyroid adenomas and thyroid carcinomas, STAT3, VEGF-C positive rate of expression gradually increased, the differences were statistically significant (P<0.01), andthere is a positive correlation between the two (r = 0.704, P<0.01).The expression of STAT3 in thyroid carcinoma is highly significant for age at diagnosis, tumor stageâ…¢/â…£, nodal metastasis, capsular invasion and multifocal.The expression of VEGF-C in thyroid carcinoma is highly significant for tumor size, nodal metastasis, capsular invasion and multifocal.STAT3 siRNA remarkably inhibited the expression of STAT3 gene in human thyroid carcinoma cell line SW579. By MTT assay, STAT3 siRNA has inhibition effects on the growth of SW579 cells.Meanwhile, STAT3 siRNA induced decrease in MMP2 and MMP9 mRNA expression in SW579 cells. By Transwell Invasion Chamber Experiment suggested that STAT3 gene silencing diminished the capacity of tumor invasion in vitro.CONCLUSION:The expression of STAT3 and VEGF-C between thyroid cancer and benign thyroid, as well as capsular invasion or lymph node metastasis were statistically significant. The expression of these two positive correlation. Their synergies, helping tumor cells spread to the lymph nodes more easily. Detection of STAT3 and VEGF-C expression level in thyroid cancer specimens after surgery, Will help to predict invasion and metastasis of thyroid cancer, and provide a more objective reference for clinical treatment and prognosis. STAT3 siRNA could significantly inhibit SW579 cells to proliferate and Invasion, it may become one of the new target of gene therapy to thyroid cancer.