u-0126 and Thyroid-Carcinoma--Anaplastic

Proto-oncogene mutations and abnormal activation of mitogen-activated protein kinase (MAPK) signalling are recurrently found in thyroid cancers. Some thyroid neoplasms respond to drugs that inhibit MAPK pathway activation. Previously, we showed that pharmacological inhibition of MAPK in thyroid cancer cells inhibits cell proliferation and upregulates L-GILZ (long glucocorticoid-induced leucine zipper), a protein with anti-oncogenic and antiproliferative activity, and that L-GILZ is partially responsible for the antiproliferative activity of MAPK inhibitors. Here, we demonstrate that pharmacological inhibition of MAPK in the anaplastic thyroid cancer cell line CAL-62 upregulated L-GILZ, which bound nuclear factor κB (NF-κB) and inhibited its nuclear translocation. These data demonstrate a unique L-GILZ-mediated molecular mechanism that, by trapping NF-κB in the cytoplasm, contributes to the inhibition of proliferation induced by drugs targeting the MAPK transduction cascade. Enhanced knowledge of the mechanism of action of MAPK pathway-inhibiting drugs may improve their clinical use.

Topics: Apoptosis; Butadienes; Cell Proliferation; Enzyme Inhibitors; Humans; NF-kappa B; Nitriles; Protein Interaction Domains and Motifs; Protein Transport; Proto-Oncogene Mas; Thyroid Carcinoma, Anaplastic; Thyroid Neoplasms; Transcription Factors; Tumor Cells, Cultured

Tumor microenvironment influences targeted drug therapy. In this study we compared drug responses to RAF and MEK inhibitors on tumor cell migration in 2D and 3D culture of BRAF(V600E) mutant cell lines derived from human papillary (BCPAP) and anaplastic (SW1736) thyroid carcinomas. Scratch wounding was compared to a double-layered collagen gel model developed for analysis of directed tumor cell invasion during prolonged culture. In BCPAP both PLX4720 and U0126 inhibited growth and migration in 2D and decreased tumor cell survival in 3D. In SW1736 drugs had no effect on migration in 2D but decreased invasion in 3D, however this related to reduced growth. Dual inhibition of BRAF(V600E) and MEK reduced but did not prevent SW1736 invasion although rebound phosphorylation of ERK in response to PLX4720 was blocked by U0126. These findings indicate that anti-tumor drug effects in vitro differ depending on culture conditions (2D vs. 3D) and that the invasive features of anaplastic thyroid cancer depend on non-MEK mechanism(s).

Topics: Antineoplastic Agents; Butadienes; Carcinoma; Cell Culture Techniques; Cell Line, Tumor; Cell Movement; Cell Survival; Humans; Indoles; Mitogen-Activated Protein Kinases; Mutation; Neoplasm Invasiveness; Nitriles; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Signal Transduction; Sulfonamides; Thyroid Carcinoma, Anaplastic