The Proliferations Inhibition Of Thyroid Cancer Cells And Vascular Endothelial Cells By Tivozanib And Pazopanib Under Cell Cycle Arrest

This paper is investigate the in vitro effect of tyrosine kinase inhibitorsof vascular endothelial growth factor receptor, tivozanib and pazopanib, onthe proliferations of both thyroid cancer cells and vascular endothelial cellsand the underlying mechanisms.The cultured human anaplastic thyroid carcinoma cell line SW579andhuman umbilical vein endothelial cell line HUVEC were exposed totivozanib and pazopanib at different concentrations (1,2,4,8and16μM)for up to72hours, and the drug-untreated cells were as control group. Theeffects of tivozanib and pazopanib on the cell proliferations were assessedby cell viability assay, cell imaging analysis and mitosis index measurewith immunofluorecent staining of mitosis cells. Cell cycle analysis wasperformed by flow cytometry.Cell viability assay indicated that tivozanib or pazopanib inhibited theproliferations of both SW579and HUVEC (p<0.05), in time-anddose-dependent manners. It showed that the estimated IC50of tivozanib inSW579and HUVEC were4μM and8μM, and the estimated IC50ofpazopanib in SW579and HUVEC were2μM and4μM, respectively. Cellimaging analysis showed that tivozanib or pazopanib at IC50inhibited thegrowths of SW579and HUVEC significantly, with significant decrease inthe cell density. Immunofluorecent staining for mitosis cells demonstratedthat the mitosis index (0.89%) of the tivozanib-treated SW579at48hourswas lower than that (2.21%) of control cells significantly (p<0.05), and alsothe mitosis index (2.26%) of tivozanib-treated HUVEC at48hours was lower than that (3.98%) of control cells significantly (p<0.01); the mitosisindex (0.91%) of the pazopanib-treated SW579at48hours was lower thanthat (2.21%) of control cells significantly (p<0.01), and also the mitosisindex (1.93%) of pazopanib-treated HUVEC at48hours was lower thanthat (3.98%) of control cells significantly (p<0.01). Flow cytometrydemonstrated that tivozanib induced SW579cells to arrest at G1phase, butarrested HUVEC at G2/M phase of the cell cycle. At48hours, thepercentage (72.5%) of tivozanib-treated SW579in G1phase was highersignificantly than that (54.4%) of control cells (p<0.05), while thepercentage (48.6%) of tivozanib-treated HUVEC in G2/M phase washigher significantly than that (14.1%) of control cells (p<0.05). Flowcytometry demonstrated that pazopanib induced SW579cells to arrest atG1phase, but arrested HUVEC at S phase of the cell cycle. At48hours,the percentage (69.2%) of pazopanib-treated SW579in G1phase washigher than that (56.3%) of control cells (p<0.05), while the percentage(44.6%) of pazopanib-treated HUVEC in S phase was higher significantlythan that (31.7%) of control cells (p<0.05).Tivozanib and pazopanib inhibits the proliferations of both SW579and HUVEC by inducing cell cycle arrest at different phases. It is indicatedthat tivozanib and pazopanib, as new tyrosine kinase inhibitors, can be usedfor the treatment of thyroid cancer by targeting both tumor cells andvascular endothelial cells related to tumor angiogenesis.