title: MEK inhibition induces apoptosis in osteosarcoma cells with constitutive ERK1/2 phosphorylation.
abstract: Conventional high-grade osteosarcoma is the most common primary bone cancer with relatively high incidence in young people. Recurrent and metastatic tumors are difficult to treat. We performed a kinase inhibitor screen in two osteosarcoma cell lines, which identified MEK1/2 inhibitors. These inhibitors were further validated in a panel of six osteosarcoma cell lines. Western blot analysis was performed to assess ERK activity and efficacy of MEK inhibition. A 3D culture system was used to validate results from 2D monolayer cultures. Gene expression analysis was performed to identify differentially expressed gene signatures in sensitive and resistant cell lines. Activation of the AKT signaling network was explored using Western blot and pharmacological inhibition. In the screen, Trametinib, AZD8330 and TAK-733 decreased cell viability by more than 50%. Validation in six osteosarcoma cell lines identified three cell lines as resistant and three as sensitive to the inhibitors. Western blot analysis of ERK activity revealed that sensitive lines had high constitutive ERK activity. Treatment with the three MEK inhibitors in a 3D culture system validated efficacy in inhibition of osteosarcoma viability. MEK1/2 inhibition represents a candidate treatment strategy for osteosarcomas displaying high MEK activity as determined by ERK phosphorylation status.
authors.affiliation: Division of Toxicology, Leiden/Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.
authors.forename: Zuzanna
authors.initials: Z
authors.lastname: Baranski
authors.affiliation: Division of Toxicology, Leiden/Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.
authors.forename: Tijmen H
authors.initials: TH
authors.lastname: Booij
authors.affiliation: Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Marieke L
authors.initials: ML
authors.lastname: Kuijjer
authors.affiliation: Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: de Jong
authors.affiliation: Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Cleton-Jansen
authors.affiliation: Division of Toxicology, Leiden/Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.
authors.forename: Leo S
authors.initials: LS
authors.lastname: Price
authors.affiliation: Division of Toxicology, Leiden/Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.
authors.forename: Bob
authors.initials: B
authors.lastname: van de Water
authors.affiliation: Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Judith V M G
authors.initials: JV
authors.lastname: Bovée
authors.affiliation: Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Pancras C W
authors.initials: PC
authors.lastname: Hogendoorn
authors.affiliation: Division of Toxicology, Leiden/Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.
authors.forename: Erik H J
authors.initials: EH
authors.lastname: Danen
keywords: 3D culture; ERK phosphorylation; MEK; osteosarcoma; pharmacological inhibition