Selective inhibition of V600E-mutant BRAF gene induces apoptosis in thyroid carcinoma cell lines

Purpose@#Papillary thyroid cancer (PTC) has a high incidence of BRAF V600E mutation. The purpose of this study was to evaluate the potential relationship between thyroiditis and BRAF V600E mutation status in patients with PTC. We investigated how a selective inhibitor of BRAF V600E PLX4032 affects the proliferation and inflammatory cytokine levels of thyroid cancer. @*Methods@#Two thyroid cancer cell lines TPC1 and 8505C were treated with PLX4032, an analysis was done on cell growth, cell cycle, the degree of apoptosis, and levels of inflammatory cytokines. To identify the functional links of BRAF, we used the STRING database. @*Results@#Docking results illustrated PLX4032 blocked the kinase activity by exclusively binding on the serine/threonine kinase domain. STRING results indicated BRAF is functionally linked to mitogen-activated protein kinase. Both cell lines showed a dose-dependent reduction in growth rate but had a different half maximal inhibitory concentration value for PLX4032. The reaction to PLX4032 was more sensitive in the 8505C cells than in the TPC1 cells. PLX4032 induced a G2/ M phase arrest in the TPC1 cells and G0/G1 in the 8505C cells. PLX4032 induced apoptosis only in the 8505C cells. With PLX4032, the TPC1 cells showed decreased levels of vascular endothelial growth factor, granulocyte-macrophage colonystimulating factor, chemokine (C-C motif) ligand 2/monocyte chemoattractant protein 1, whereas the 8505C cells showed significantly decreased levels of IL-8, serpin E1/plasminogen activator inhibitor-1, and matrix metalloproteinase (MMP)-3. @*Conclusion@#PLX4032 was cytotoxic in both TPC1 and 8505C cells and induced apoptosis. In the 8505C cells, inflammatory cytokines such as IL-8 and MMP-3 were down-regulated. These findings suggest the possibility that the BRAF V600E mutation needs to target inflammatory signaling pathways in the treatment of thyroid cancer.

Selective B-RAF V600E Inhibitor PLX4032 Inhibits the Growth of Breast Cancer Cell Lines through Cell Cycle Arrest

PURPOSE: Breast cancer is the most common invasive cancer and the second common cause of death among women worldwide. Many researchers have focused on the effective treatment of advanced breast cancer using new drugs. Herein, we analyzed whether PLX4032, a B-RAF V600E inhibitor, could be used as a novel treatment for advanced breast cancer. METHODS: Two breast cancer cell lines, MCF7 and MDA-MB-231, were treated with the selective B-Raf inhibitor PLX4032 under adherent culture conditions and the effects of PLX4032 on cell growth, cell cycle duration, apoptosis and cell cycle related genes expression were evaluated. RESULTS: We found that PLX4032 dose-dependently inhibited cell growth in both cell lines through cell cycle arrest at phase G0/G1. However, PLX4032 treatment did not have a significant effect on cell apoptosis. In addition, CCNA2 gene expression was significantly decreased in the MCF7 cells in a dose-dependent manner. CONCLUSION: Our data demonstrated that treatment of breast cancer with PLX4032 could inhibit proliferation through cell cycle arrest. Therefore, PLX4032 might be a novel anticancer drug that can be used in the treatment of advanced breast cancer.