Study Of Factors Affecting Lymph Node Metastasis Of Papillary Thyroid Carcinoma

Thyroid cancer is the most common endocrine malignancy,with papillary thyroid carcinoma(PTC)aecounting for approxirnately 80%of all thyroid malignancies.The incidence of PTC is rising every year.Although PTC is usually indolent and curable with surgical thyroidectomy,often followed by radioiodine treatment,many patients suffer metastasis and disease recurrence,which in some cases proves to be incurable and fatal.To improve the survival rate and life quality of the latter,it is important to give the best treatment including operation.However,there are debates on which is the most appropiate operation for PTC in the world.Identifying these high-risk patients at the time of diagnosis through well-established prognostic factors by different prognostic scoring systems is now the main method which can help to ascertain the most appropriate treatment for these patients.These prognostication have traditionally been based on the presence or absence of certain clinical risk factors and can not identify the more aggressive PTC,so they can not contribute to decision making about the optimal extent of initial surgery.With the development of molecular biology and immunology,scientists are searching for the molecular biomarkers which can indicate the prognosis of differentiated thyroid carcinoma and can improve or substitute the old prognostic scoring systems.Regulatory T cell(Treg)play an important role in suppressive control of immune responses to tumors and confers a dominant mechanism for tumor immune escape.Foxp3 is so far the most specific marker for Treg cells. Identified with this marker,the presence of Treg cells within several malignant tumors have been shown to predict the invasiveness,metastatic ability and prognosis of tumors.It still remain unknown if Foxp3 can be the marker of metastasis and prognosis of PTC.RET rearrangement and BRAF mutation represent the most important molecular pathogenesis in PTC.There are controvercies whether they can predict the metastasis and prognosis of PTC.P53 is the most commonly mutated gene in human cancer.It is easy for cells who have P53 mutation to obtain damage of other genes and P53 mutation is usually detected in aggressive tumors.β-catenin is a cytoplasmic protein which connect E-cadherin to the cytoskeleton filament and is also an important component of Wnt pathway.Its abnormal expression has close relation with the progression of dedifferentiation of tumor. Osteopontin is an important protein in extracellular matrix and it correlates with the growth, proliferation,invasiveness and metastasis of tumor cells.The relationship between the three biomarkers and metastasis of PTC need to be investigated.This work focused on the relationship between Treg cell,RET rearrangement,BRAF mutation, P53,β-catenin,osteopontin and lymph node metastasis of PTC.The relationship between the above six indexes and clinical factors of PTC is investigated too.We analyzed the relationship among the six indexes at the same time.SectionⅠExpression of Foxp3 in PTC and its relationship with lymph node metastasisTo investigate if Treg cells are related to lymph node metastasis or other clinical factors of PTC.Foxp3mRNA in specimen of PTC and benign thyroid disease was detected by Fluorescence Quantitive Polymerase Chain Reaction(FQ-PCR).The expression of Foxp3mRNA in peripheral blood was detected by the same method too.The results were analyzed.Flow cytometrie analysis was used to detect Foxp3~+T cells and CD4~+CD25~+T cells in the peripheral blood of PTC patients and patients suffered from benign thyroid disease.Foxp3 protein in PTC and benign thyroid disease specimen was detected by immunochemistry.Our data indicated that the level of Foxp3 mRNA in PTC was higher than that of benign lesion of thyroid significantly.The level of Foxp3 mRNA in PTMC was higher than that of other PTC significantly too The number of Foxp3~+T cells in PTC was more than that of benign lesion.The level of Foxp3 mRNA in PTC was related to the age of the patients and the number of metastatic lymph nodes.The older the patient was,the higher the level of Foxp3 mRNA in PTC was.However there was no significant difference of the level of Foxp3 rnRNA between PTC with and without lymph node metastasis.There was no significant difference of the level of Foxp3 mRNA in peripheral blood between PTC and benign disease.SectionⅡThe expression of P53,β-cat and OPN in PTC and their relationship with lymph node metastasisTo investigate the relationship between the expression of P53,β-cat,OPN and lymph node metastasis and other clinical factors of PTC.The expression of P53,β-cat and OPN was detected by immunochemistry.Our data indicated that the abnormal expression of P53 was related to the lymph node metastasis of PTC and abnormal OPN expression significantly.There was positive correlation between P53 and the number of metastatic lymph node,the number of Foxp3~+T cells.Also there was significant correlation between abnormal expression ofβ-cat and lymph node metastasis.And the number of metastatic lymph node was correlated positively with abnormalβ-cat expression.The abnormal expression ofβ-cat occurred more frequent in multifocal PTC than PTC with one locus.SectionⅢThe relationship between BRAF mutation,RET rearrangement and lymph node metastasisTo analyse the relationship between BRAF mutation,RET rearrangement and lymph node metastasis,other clinical factors of PTC.Summarize all the factors which can predict lymph node metastasis of PTC.BRAF mutation was detected by sequencing.RET/PTC1 and RET/PTC3 rearrangement were detected by reverse transeriptase polymerase chain reaction(RT-PCR).The positive amplified products were completely sequenced to confirm the rearrangement.Our data indicated that PTC with normalβ-cat expression had BRAF mutation more frequently.There was no correlation between RET rearrangement,BRAF mutation and lymph node metastasis.The lymph node metastasis was correlated with abnormal expression of P53,β-cat significantly.PTC patients who were younger than 43 years had lymph node metastasis more frequently.Summary1.Treg cells may play a role in the formation of PTC.2.The number of Treg cells in the tissue of PTC do not correlate with Lymph node metastasis of PTC.3.The abnormal OPN expression is correlated with P53 mutation.4.The abnormalβ-cat expression is negatively correlated to BRAF mutation in PTC.5.With abnormal expression of P53,β-cat,PTC patients are at high risk of Lymph node metastasis which is also true if the patient is younger than 43 years.Neck dissection should be considered for these patients.