| Thyroid cancer is the most common malignant tumor of the endocrine system.In recent decades,the incidence of thyroid cancer was increased constantly,which has become the fifth most common women’s malignant tumor in China and America.Therefore,thyroid cancer has been widely concerned by the medical community.Papillary thyroid carcinoma(PTC)is the most common pathological type of thyroid cancer,the overall therapeutic effect and prognosis is relatively good.However,the treatment effect of patients with advanced and high-risk subtypes is still poor.Thyroid suppression or replacement therapy is mostly required after thyroid cancer surgery,which has a great impact on the quality of life for patients.Therefore,it is necessary to study the molecular mechanism and clinical treatment of PTC.Apoptotic protease activator 1(Apaf-1)is a core protein in mitochondrial dependent apoptosis pathway.It is currently believed that the inhibition of this pathway is positively correlated with the formation and development of tumors.Studies have shown that the expression level of Apaf-1 is decreased in a variety of tumors and is correlated with the proliferation,apoptosis and drug resistance of tumor cells.We found there no study on Apaf-1 in PTC after searched domestic and foreign literature.As a relatively well-differentiated endocrine tumor,the study on the relationship between PTC and Apaf-1 expression and function can provide new evidence for the study on mitochondrial dependent apoptosis pathway in PTC.The purpose of this study was to investigate the changes of Apaf-1 expression in PTC tissues and its effects on the proliferation,apoptosis and migration of PTC cells.In addition,we explored the changes of the caspase-mediated apoptosis pathway after the up-regulation and down-regulation of Apaf-1 expression,in order to provide a new reference for the molecular mechanism of PTC pathogenesis.In this study,Real-time PCR,Western blot and immunohistochemistry were applicated to investigate and compare the mRNA and protein expression of Apaf-1 in PTC and paracancer tissues,and to analyze the relationship between Apaf-1 expression and PTC clinicopathological characteristics.The expression of Apaf-1 in PTC cell line CGTHW-3 and normal thyroid cell line Nthy-ori 3-1 were compared by Real-time PCR and Western blot.The influence of Apaf-1 on cell proliferation,apoptosis and migration was verified by down-regulating and up-regulating the expression of Apaf-1 in CGTHW-3 cells by siRNA and expression plasmid.The results showed that the mRNA and protein expression of Apaf-1 in PTC tissues were significantly lower than that in paracancer tissues(P < 0.05),and the pathological analysis showed that Apaf-1 expression had no significant relationship with the gender,age,tumor size,lymphatic metastasis and TNM stage of tumor patients(P > 0.05).Cell experiments showed the expression of Apaf-1 in CGTHW-3 cells was lower than that in Nthy-ori 3-1(P< 0.05).Down-regulation of Apaf-1 expression enhanced the proliferation activity of CGTHW-3 cells(P< 0.05),while up-regulation of Apaf-1 expression significantly decreased the proliferation activity of CGTHW-3 cells(P < 0.05)and increased the apoptosis(P < 0.05).However,Apaf-1 expression regulation had no significant effect on cell migration ability(P > 0.05).We further analyzed the protein expression changes of caspase-9,caspase-3,caspase-6 and caspase-7 at low expression and high expression of Apaf-1,and the results showed that the expression of these four kinds of caspase proteins were positively correlated with the expression of Apaf-1.Therefore,it can be speculated that Apaf-1 promotes cell apoptosis by activating the caspase pathway protein,and its effect on cell proliferation activity may be due to the change of apoptosis pathway to prolong or shorten the cell survival time. |
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