Expression And Mechanistic Investigation Of TAGLN In Thyroid Papillary Carcinoma

Objective: To explore the role and influence of TAGLN in papillary thyroid carcinoma,to find the related signaling pathways,and to search for potential intervention targets for the treatment of papillary thyroid carcinoma.Methods: A total of 100 cases PTC tissues and corresponding paracancerous normal thyroid tissues were collected from PTC patients who suffered from papillary thyroid carcinoma and underwent thyroidectomy in the affiliated hospital of Qingdao university from June 2018 to June 2019.RNA and protein were extracted from the tissue samples.Respectively,using real-time quantitative PCR and Western blot method to analyze the differences of the expression of TAGLN in the PTC tissues and corresponding paracancerous normal thyroid tissues.At the same time,using immunohistochemical staining method to analyze the positioning of TAGLN;PTC cells were transfected with TAGLN overexpressed plasmid to overexpress the content of TAGLN in the cells.In addition,sh RNA lentiviral vector was used to transfect PTC cells.The transfection efficiency was verified by RT-qPCR and Western blot.CCK-8 cell proliferation assay was used to investigate the effects of overexpression and RNA interference TAGLN on the proliferation ability of PTC cells.Transwell cell invasion and migration assay was used to detect the effects of overexpression and RNA interference TAGLN on invasion and migration of PTC cells.The effect of RNA interference with TAGLN sh RNA on tumor proliferation was investigated by subcutaneous injection of BCPAP cells with stable expression of TAGLN sh RNA into nude mouse.Western blot was used to detect the effects of overexpression and RNA interference with TAGLN on the activity of MAPK/ERK signaling pathway in PTC cells.SPSS 24.0 was used for statistical analysis,and Graph Pad Prism 8 was used for plotting.Results: RT-qPCR confirmed that there was no significant difference in the relative mRNA expression level of TAGLN between PTC and corresponding paracancerous normal thyroid tissues(P>0.05);Western blot results showed that the protein relative expression level of TAGLN in PTC tissues was significantly lower than that in paracancerous normal thyroid tissues(P <0.0001);Immunohistochemical results showed that the number of positive cells with high expression of TAGLN in PTC tissues was significantly lower than that in paracancerous normal thyroid tissues,and it was mainly distributed in thyroid follicular epithelial cells and interstitial tissue.Using CCK-8 assay to detect the effect of overexpression and knockdown of TAGLN on the proliferation ability of PTC cells,which the result demonstrated the proliferation ability of BCPAP and TPC-1 cells with overexpression of TAGLN was significantly lower than that of control group,while the proliferation ability of TAGLN sh RNA group was significantly increased compared with the control group;Transwell cell invasion and migration assay showed that the invasion and migration ability of BCPAP and TPC-1 cells with overexpression of TAGLN was remarkably reduced compared with the control group,and the ability of cell invasion and migration in TAGLN sh RNA group was obviously increased compared with the control group.The nude mouse tumorigenicity assay further confirmed that TAGLN knockdown distinctly promoted tumor growth.Verification of the signaling pathway associated with detection of protein levels by Western blot showed that overexpression of TAGLN could notably reduce the phosphorylation level of extracellular regulatory protein kinase(ERK)in PTC cells,while the level of ERK phosphorylation was markedly increased after RNA interference with TAGLN.Conclusion: 1.The protein relative expression level of TAGLN in PTC tissue was significantly lower than that in the corresponding paracancerous normal thyroid tissue,mainly distributed in thyroid follicular epithelial cells.2.Overexpression of the TAGLN notably inhibited the proliferation,invasion and migration of PTC cells,while RNA interference with the TAGLN obviously enhanced the proliferation,invasion and migration of PTC cells.3.The effect of TAGLN on cell proliferation,invasion and migration of PTC cells by inhibiting the activation of MAPK/ERK signaling pathway.4.As a tumor suppressor gene,TAGLN plays an important role in the occurrence and development of PTC.