ABSTRACT
Inhibition of basal Jun kinase (JNK) activity by small interfering RNAs (siRNAs) enhances cisplatin sensitivity and decreases DNA repair in T98G glioblastoma cells. Although the JNK pathway has been extensively studied in recent years, little is known concerning the signaling pathways that control their expression in glioma cells. The aim of the present study was to assess the role of c-Jun-NH2-terminal kinases (JNKs) in the regulation of T98G glioblastoma cells treated with cisplatin in the presence or absence of siRNAs against JNK1 and JNK2. Addition of either small interfering JNK1-siRNA or JNK2-siRNA induced decreased DNA repair and sensitized the T98G glioblastoma cells to the DNA damaging drug cisplatin (cis-diamminedichloroplatinum). This effect was associated with reduced cell survival and loss of anchorageindependent colony formation. The results indicate that effective inhibition of the JNK pathway significantly sensitizes glioblastoma cells to cisplatin, a compound of proven clinical value whose spectrum of application is limited by resistance phenomena.
Subject(s)
Brain Neoplasms/drug therapy , Cisplatin/pharmacology , DNA Repair/drug effects , Glioblastoma/drug therapy , JNK Mitogen-Activated Protein Kinases/genetics , RNA, Small Interfering/pharmacology , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Apoptosis/genetics , Brain Neoplasms/genetics , Brain Neoplasms/metabolism , Cell Line, Tumor/drug effects , Cell Survival/drug effects , Cell Survival/genetics , DNA Repair/genetics , Gene Knockdown Techniques , Glioblastoma/genetics , Glioblastoma/metabolism , Humans , JNK Mitogen-Activated Protein Kinases/metabolism , MAP Kinase Kinase 7/genetics , MAP Kinase Kinase 7/metabolism , Mitogen-Activated Protein Kinase 8/genetics , Mitogen-Activated Protein Kinase 8/metabolism , Proto-Oncogene Proteins c-bcl-2/genetics , Proto-Oncogene Proteins c-bcl-2/metabolism , RNA, Small Interfering/genetics , bcl-2-Associated X Protein/genetics , bcl-2-Associated X Protein/metabolismABSTRACT
Viral manipulation of transduction pathways associated with key cellular functions such as survival, response to microbial infection, and cytoskeleton reorganization can provide the supportive milieu for a productive infection. Here, we demonstrate that vaccinia virus (VACV) infection leads to activation of the stress-activated protein kinase (SAPK)/extracellular signal-regulated kinase (ERK) 4/7 (MKK4/7)-c-Jun N-terminal protein kinase 1/2 (JNK1/2) pathway; further, the stimulation of this pathway requires postpenetration, prereplicative events in the viral replication cycle. Although the formation of intracellular mature virus (IMV) was not affected in MKK4/7- or JNK1/2-knockout (KO) cells, we did note an accentuated deregulation of microtubule and actin network organization in infected JNK1/2-KO cells. This was followed by deregulated viral trafficking to the periphery and enhanced enveloped particle release. Furthermore, VACV infection induced alterations in the cell contractility and morphology, and cell migration was reduced in the JNK-KO cells. In addition, phosphorylation of proteins implicated with early cell contractility and cell migration, such as microtubule-associated protein 1B and paxillin, respectively, was not detected in the VACV-infected KO cells. In sum, our findings uncover a regulatory role played by the MKK4/7-JNK1/2 pathway in cytoskeleton reorganization during VACV infection.