Study The Effect Of FOXQ1 On The Biological Behavior Of Papillary Thyroid Carcinoma And Its Mechanisms

Thyroid cancer has been the most common malignant tumor in the endocrine system with a rapidgrowth of incidence in recent years,which was one of the fastest growing tumors of human malignant tumor.Papillary thyroid carcinoma(PTC)is the most common pathological type in all thyroid cancer,accounting for approximately 80% of thyroid cancer.Most patients with PTC have a good prognosis due to the high degree differentiation and slow growthof tumor,but their overall recurrence rate is as high as 35%,and about 10% of PTC patients have a low survival rate due to recurrence and / or distant metastasis.Therefore,it is still necessary to explore the molecular mechanism of PTC occurrence and development.The forkhead box Q1(FOXQ1)protein belongs to the forkhead box(FOX)transcription factor family.It has been found that multiple FOX family factors play a key role in the pathogenesis of tumor progression.Recent studies suggest that FOXQ1 is another important member of the gene family which is closely related to tumor progression.It has been reported that FOXQ1 plays an important role in the development and progression of many different types of tumors,and its function mainly involves the immune escape in the process of malignant transformation of normal cells;epithelial-mesenchymal transition EMT)process;cell proliferation,apoptosis,drug resistance,angiogenesis,lymphatic metastasis during the process of tumor progression and so on.However,there was no report related to its research in PTC been retrieved.This study focused on the association of FOXQ1 and PTC lymphatic metastasis.Furthermore,matrix metalloproteinases(MMPs)act as important roles in the signal pathways of tumor metastasis,matrix metalloproteinase-2(MMP-2)and MMP-9 were particularly known as vital molecules in tumor invasion and metastasis,which could be used as a molecular marker to predict the tumor development and prognosis.There were studies suggested that MMP-2,MMP-9 both were positively correlated to thyroid carcinoma lymph node metastasis,and that their expression levels may help to diagnose the possibility of lymph node metastasis in thyroid cancer.Therefore,investigate the role of FOXQ1 in thyroid papillary carcinoma and its correlation with the expression levels of MMP-2 and MMP-9 in the invasion and metastasis process of papillary thyroid carcinoma,will contributing to early screening of high-risk patients,early diagnosis,and detection of lymph node metastasis in PTC,and could provided a new evidence for the diagnosis and treatment of thyroid papillary.In this study,we firstly detected the expression levels of FOXQ1 mRNA and protein in PTC and normal thyroid tissues by real-time PCR,Western blot and immunohistochemistry,and evaluated the relationship between FOXQ1 expression levels and the clinicopathological features in PTC.Then down-regulated the expression of FOXQ1 in thyroid papillary carcinoma cell line CGTHW-3 by using RNA interference to silence genes involved,studied the effects of FOXQ1 gene silencing on the proliferation,invasion and migration of PTC cells,and explored the underlying molecular mechanism.Real-time PCR and Western blot results show that in PTC the expression of FOXQ1 mRNA and protein expression levels were significantly higher than that in normal thyroid tissues(P<0.001),and the high levels of FOXQ1 mRNA and protein were positively correlated to the status of lymphatic metastasis and the stage of TNM in PTC(P<0.01),but there no significant relationship with gender,age,tumor size,concurrent Hashimoto's thyroiditis(HT)was identified(P>0.05).The result of immunohistochemical further confirmed that in PTC FOXQ1 protein expressionpositive rate(81.43%)was significantly higher than normal thyroid tissues(42.22%,P<0.001),and the correlation between positive rate and clinical pathological characteristics involved analysis shows that the expression rate of FOXQ1 was positively associated with lymphaden metastasis in PTC(P<0.05).We successfully silenced the expression of FOXQ1 in papillary thyroid carcinomacell line CGTHW-3 using siRNA gene interference technology,and the knock down efficiency of FOXQ1 mRNA and protein were detect by Real-time PCR and Western-blot.Then we studied the effects of FOXQ1 gene silencing on the biological behavior of PTC cells.The results of CCK8 and colony formation test showed that the proliferation and colony formationability of GTHW-3 cells were significantly suppressed in in the group of siRNA,compared with negative control and untreated group(P<0.05).The results of cell scratch test showed that the cell healing anddirectional migration ability of CGTHW-3 cells were inhibited in after FOXQ1 expression been downregulated(P<0.05).The transwell invasion assay of cells in vitro showed that the invasion ability of cell lines was significantly decreased in siRNA treated group(P<0.05).Western blot results demonstrated that MMP-2 and MMP-9 excluding other critical signaling molecules the levels of protein expression was significantly down-regulated in CGTHW-3 cells after FOXQ1 gene expression silencing(P<0.05).In summary,the high expression of FOXQ1 in PTC tissue and its inhibition of PTC cell proliferation,invasion and migration after gene silencing indicated that FOXQ1 served as an important oncogene in the development of PTC;FOXQ1 maybe involved in the regulation of MMPs act as a transcription factor since it can regulate the expression of MMP-2 and MMP-9 directly or indirectly;FOXQ1 may take part in the MMPs involved signal pathway through regulate MMP-2 and MMP-9 protein levels,and contributing to the tumor invasion and metastasis of PTC.