LIM domain kinases as potential therapeutic targets for neurofibromatosis type 2

• Published in: Oncogene Vol. 33; no. 27; pp. 3571 - 3582
• Main Authors: Petrilli, A, Copik, A, Posadas, M, Chang, L-S, Welling, D B, Giovannini, M, Fernández-Valle, C
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.07.2014; Nature Publishing Group
• Subjects: 631/67/1059/602; 631/67/1922; Actin; Actin Depolymerizing Factors - metabolism; Animals; Apoptosis; Apoptosis - drug effects; Aurora Kinase A - metabolism; Breast; Caspase; Cdc42 protein; Cell Biology; Cell cycle; Cell growth; Cell Proliferation - drug effects; Cell Survival - drug effects; Cofilin; Cytoskeleton; G2 Phase Cell Cycle Checkpoints - drug effects; Gene Silencing; Genetic aspects; Genetic disorders; Health aspects; Human Genetics; Humans; Internal Medicine; Kinases; LIM kinase; Lim Kinases - antagonists & inhibitors; Lim Kinases - deficiency; Lim Kinases - genetics; Lim Kinases - metabolism; M Phase Cell Cycle Checkpoints - drug effects; Medicine; Medicine & Public Health; Mice; Mitosis; Mitosis - drug effects; Molecular Targeted Therapy; Muscle proteins; Mutation; Neurofibromatosis; Neurofibromatosis 2; Neurofibromatosis 2 - drug therapy; Neurofibromatosis 2 - enzymology; Neurofibromatosis 2 - metabolism; Neurofibromatosis 2 - pathology; Neurofibromin 2; Neurofibromin 2 - genetics; Neurofibromin 2 - metabolism; Neurological disorders; Oncology; original-article; Phosphoproteins - metabolism; Phosphorylation - drug effects; Phosphotransferases; Prostate; Protein Kinase Inhibitors - pharmacology; Protein Kinase Inhibitors - therapeutic use; Schwann cells; Schwann Cells - cytology; Schwann Cells - drug effects; Schwann Cells - metabolism; Schwann Cells - pathology; Therapeutic targets; Tumors; Vestibular system; Viability; United States; LIMK; cell proliferation; cell cycle; schwannomas; Neurofibromatosis; cytoskeleton dynamics
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2013.320

Neurofibromatosis type 2 (NF2) is caused by mutations in the NF2 gene that encodes a tumor-suppressor protein called merlin. NF2 is characterized by formation of multiple schwannomas, meningiomas and ependymomas. Merlin loss-of-function is associated with increased activity of Rac and p21-activated kinases (PAKs) and deregulation of cytoskeletal organization. LIM domain kinases (LIMK1 and 2) are substrate for Cdc42/Rac-PAK and modulate actin dynamics by phosphorylating cofilin at serine-3. This modification inactivates the actin severing and depolymerizing activity of cofilin. LIMKs also translocate into the nucleus and regulate cell cycle progression. Significantly, LIMKs are overexpressed in several tumor types, including skin, breast, lung, liver and prostate. Here we report that mouse Schwann cells (MSCs) in which merlin function is lost as a result of Nf2 exon2 deletion ( Nf2 ΔEx2 ) exhibited increased levels of LIMK1, LIMK2 and active phospho-Thr508/505-LIMK1/2, as well as phospho-Ser3-cofilin, compared with wild-type normal MSCs. Similarly, levels of LIMK1 and 2 total protein and active phosphorylated forms were elevated in human vestibular schwannomas compared with normal human Schwann cells (SCs). Reintroduction of wild-type NF2 into Nf2 ΔEx2 MSC reduced LIMK1 and LIMK2 levels. We show that pharmacological inhibition of LIMK with BMS-5 decreased the viability of Nf2 ΔEx2 MSCs in a dose-dependent manner, but did not affect viability of control MSCs. Similarly, LIMK knockdown decreased viability of Nf2 ΔEx2 MSCs. The decreased viability of Nf2 ΔEx2 MSCs was not due to caspase-dependent or -independent apoptosis, but rather due to inhibition of cell cycle progression as evidenced by accumulation of cells in G 2 /M phase. Inhibition of LIMKs arrests cells in early mitosis by decreasing aurora A activation. Our results suggest that LIMKs are potential drug targets for NF2 and tumors associated with merlin deficiency.