ABSTRACT
Extracellular signal-regulated protein kinase 5 (ERK5) has various physiological functions. However, the physiological role of ERK5 in the treatment of mice with an illicit drug such as methamphetamine (METH) remains unknown. We revealed that mice treated with METH showed hyperactivity, and increased p-ERK5 and Iba1 (a microglia marker) levels in the striatum. Additionally, these changes were inhibited by pretreatment with the ERK5 inhibitor BIX02189. The results suggest that METH-induced hyperactivity is associated with the activation of microglia via p-ERK5 in the striatum. Thus, the ERK5 pathway components in the central nervous system are potential therapeutic targets for preventing METH addiction.
Subject(s)
Aniline Compounds/pharmacology , Corpus Striatum/cytology , Hyperkinesis/chemically induced , Hyperkinesis/drug therapy , Indoles/pharmacology , Methantheline/adverse effects , Microglia/drug effects , Mitogen-Activated Protein Kinase 7/antagonists & inhibitors , Mitogen-Activated Protein Kinase 7/physiology , Aniline Compounds/therapeutic use , Animals , Calcium-Binding Proteins/metabolism , Corpus Striatum/metabolism , Indoles/therapeutic use , Mice , Microfilament Proteins/metabolism , Microglia/metabolism , Mitogen-Activated Protein Kinase 7/metabolism , Psychomotor Agitation , Substance-Related Disorders/prevention & controlABSTRACT
Transforming growth factor-ß1 (TGF-ß1) promotes tumor metastasis by inducing an epithelial-to-mesenchymal transition (EMT) in cancer cells. In this study, we investigated the effects of BIX02189 and XMD8-92, pharmacologic inhibitors of the MEK5 [mitogen-activated protein kinase/extracellular-signal-regulated kinase (ERK)5] signaling pathway, on the EMT and migration of cancer cells induced by TGF-ß1. In human A549 lung cancer cells, TGF-ß1-induced EMT, cell motility, and expression of matrix metalloproteinase-2 were completely inhibited by BIX02189, but not by XMD8-92 or small interference RNAs specific to MEK5 and ERK5. Interestingly, BIX02189 strongly blocked the activation of TGF-ß1 signaling components, and this inhibitory effect was not reproduced by MEK5 inhibition. Molecular docking simulation and kinase assays revealed that BIX02189 binds directly to the ATP-binding site of the TGF-ß receptor type I (TßRI) and suppresses its kinase activity. Finally, the anti-metastatic effect of BIX02189 was validated in a TßRI-derived A549 xenograft mouse model. Collectively, these findings newly characterize BIX02189 as a potent inhibitor of TßRI that can block the tumor metastatic activity of TGF-ß1.
Subject(s)
Aniline Compounds/pharmacology , Antineoplastic Agents/pharmacology , Carcinoma, Non-Small-Cell Lung/drug therapy , Cell Movement/drug effects , Indoles/pharmacology , Lung Neoplasms/drug therapy , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Receptors, Transforming Growth Factor beta/antagonists & inhibitors , Transforming Growth Factor beta1/pharmacology , A549 Cells , Adenosine Triphosphate/metabolism , Aniline Compounds/metabolism , Animals , Antineoplastic Agents/metabolism , Binding Sites , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/metabolism , Carcinoma, Non-Small-Cell Lung/secondary , Dose-Response Relationship, Drug , Epithelial-Mesenchymal Transition/drug effects , Female , Humans , Indoles/metabolism , Lung Neoplasms/genetics , Lung Neoplasms/metabolism , Lung Neoplasms/pathology , MAP Kinase Kinase 5/antagonists & inhibitors , MAP Kinase Kinase 5/genetics , MAP Kinase Kinase 5/metabolism , Mice, Inbred BALB C , Mice, Nude , Mitogen-Activated Protein Kinase 7/antagonists & inhibitors , Mitogen-Activated Protein Kinase 7/genetics , Mitogen-Activated Protein Kinase 7/metabolism , Molecular Docking Simulation , Neoplasm Invasiveness , Protein Binding , Protein Serine-Threonine Kinases/metabolism , RNA Interference , Receptor, Transforming Growth Factor-beta Type I , Receptors, Transforming Growth Factor beta/metabolism , Signal Transduction/drug effects , Smad Proteins/metabolism , Transfection , Xenograft Model Antitumor AssaysABSTRACT
ERK5, encoded by MAPK7, has been proposed to play a role in cell proliferation, thus attracting interest as a cancer therapeutic target. While oncogenic RAS or BRAF cause sustained activation of the MEK1/2-ERK1/2 pathway, ERK5 is directly activated by MEK5. It has been proposed that RAS and RAF proteins can also promote ERK5 activation. Here we investigated the interplay between RAS-RAF-MEK-ERK and ERK5 signaling and studied the role of ERK5 in tumor cell proliferation in 2 disease-relevant cell models. We demonstrate that although an inducible form of CRAF (CRAF:ER*) can activate ERK5 in fibroblasts, the response is delayed and reflects feed-forward signaling. Additionally, oncogenic KRAS and BRAF do not activate ERK5 in epithelial cells. Although KRAS and BRAF do not couple directly to MEK5-ERK5, ERK5 signaling might still be permissive for proliferation. However, neither the selective MEK5 inhibitor BIX02189 or ERK5 siRNA inhibited proliferation of colorectal cancer cells harbouring KRAS(G12C/G13D) or BRAF(V600E). Furthermore, there was no additive or synergistic effect observed when BIX02189 was combined with the MEK1/2 inhibitor Selumetinib (AZD6244), suggesting that ERK5 was neither required for proliferation nor a driver of innate resistance to MEK1/2 inhibitors. Finally, even cancer cells with MAPK7 amplification were resistant to BIX02189 and ERK5 siRNA, showing that ERK5 amplification does not confer addiction to ERK5 for cell proliferation. Thus ERK5 signaling is unlikely to play a role in tumor cell proliferation downstream of KRAS or BRAF or in tumor cells with ERK5 amplification. These results have important implications for the role of ERK5 as an anti-cancer drug target.