Preliminary Study Of Roles Of FAM172A Protein In The Pathogenesis Of Papillary Thyroid Carcinoma

Part ⅠThe expression levels of FAM172 A in papillary thyroid carcinoma tissuesObjective The family with sequence similarity 172, member A(FAM172A), a novel protein, is known less about its functions till now. Our aims are to study the expression levels of FAM172 A protein in human papillary thyroid carcinoma tissues.Methods Immunohistochemistry staining and Western blot were performed to compare the expression of FAM172 A protein among human papillary thyroid carcinoma, thyroid adenoma, and normal thyroid tissues adjacent to thyroid adenoma.Results Immunohistochemistry staining and Western blot displayed that the expression of FAM172 A protein in papillary thyroid carcinoma tissues was not only significantly higher than that in normal thyroid and thyroid adenoma tissues(p<0.001), but also markedly higher than that in its adjacent tissues for the same patients.Conclusions The expression levels of FAM172 A protein was significantly higher in papillary thyroid carcinoma tissues than in normal thyroid tissues, thyroid adenoma tissues, and tissues adjacent to papillary thyroid carcinoma.thyroid carcinoma cells via p38 mitogen-activated protein kinase pathway Part Ⅱ FAM172 A protein promotes proliferation of human papillaryObjective To explore the effect of FAM172 A protein on proliferation of human papillary thyroid carcinoma cells(IHH-4) and its corresponding molecular mechanisms.Methods 1)The PDC315-FAM172 A plasmids constructed in our previous study were transfected into IHH-4 cells using liposome transfection 2000, while the PDC315 plasmids were also transfected into IHH-4 cells, which were used as a control. 2) The effect of FAM172 A protein on cell proliferation was observed by MTT assays and cell growth curve method. 3) Signaling pathways related to cell proliferation including PI3 K, p38 MAPK and AMPK were researched to find the possible mechanisms involved the roles of FAM172 A in cell proliferation. SB202190, an inhibitor of p38 MAPK, was used to further investigate the role of FAM172 A protein in cell proliferation via p38 MAPK pathway.Results 1) MTT assays demonstrated that optical density value increased by 18%when transfected with PDC315-FAMl72 A plasmids for 24 h compared with PDC315 plasmids transfection(p<0.001). The cell growth curve showed that IHH-4 cells transfected with PDC315-FAM172 A plasmids(24, 48, 72, 96 hours) grow faster than those transfected with PDC315 plasmids.2) FAM172 A could activate p38 MAPK pathway, but cannot work on PI3 K and AMPK pathways in IHH-4 cells. 3) The activated p38 MAPK pathway by FAM172 A can be blocked by SB202190, a selective inhibitor of p38 MAPK. And the pro-proliferative effect of FAM172 A on IHH-4 cells can also be remarkably attenuated by SB202190(p<0.001).Conclusions FAM172 A protein promoted IHH-4 cell proliferation via p38 MAPK pathway, which indicated that FAM172 A may play an important role in the pathogenesis of papillary thyroid carcinoma.Part Ⅲ The effects of FAM172 A on the nude mice xenograft of papillary thyroid carcinomaObjective 1) To establish the nude mice xenograft model of papillary thyroid carcinoma with the function to accumulate 99 m Tc, and to provide a tool for the further study in the pathogenesis of papillary thyroid carcinoma. 2) To preliminarily examine the effects of FAM172 A on the nude mice xenograft of papillary thyroid carcinoma.Methods 1) 1×107 cells in 200 ul suspension liquids of the human papillary thyroid carcinoma cell lines IHH-4 were inoculated into nine nude mice(fiver week-old female nude mice, BALB/c-nu/nu). Tumor formation was recorded, and the size and morphology of tumor was observed by PET-CT. Emission computed tomography(ECT) was used to observe the function of 99 mTc intaken by xenografts. 2) The IHH-4 cells transfected with either PDC315-FAM172 A plasmids or PDC315 plasmids were injected subcutaneously into the six nude mice, respectively.Tumor size, weights and activitives of the mice were recorded regularly. The expression of FAM172 A in nude mice xenograft was observed by Western blotting.Results 1) The percentage of the formation of xenografts in nude mice was 100.0%(9/9). After one week of the cells injected into nude mice, visible tumors were formed. PET-CT observed the tumor size at the fourth weeks. Xenograft’ image was displayed by ECT after 15 minutes of intraperitoneal injection of 99 mTc. 2) Compared with the control group, xenografts of nude mice transfected with PDC315-FAM172 A plasmids group were larger, heavier, and showed invasive growth. Moreover, the weight of nude mice was significantly reduced compared with control group.Conclusions 1) The nude mice xenograft model of papillary thyroid carcinoma was successfully established using the human papillary thyroid carcinoma cell lines IHH-4.The xenografts have the ability to accumulate the 99 mTc, providing a good animal model for the study of pathogenesis of papillary thyroid carcinoma. 2) FAM172 A protein can promote the invasive growth of nude mice xenograft.FAM172A protein may play an important role in the pathogenesis of papillary thyroid carcinoma.