title: A novel BH3 mimetic reveals a mitogen-activated protein kinase-dependent mechanism of melanoma cell death controlled by p53 and reactive oxygen species.
abstract: The RAS/BRAF/MEK/ERK mitogen-activated protein kinase (MAPK) pathway is emerging as a key modulator of melanoma initiation and progression. However, a variety of clinical studies indicate that inhibiting the MAPK pathway is insufficient per se to effectively kill melanoma cells. Here, we report on a genetic and pharmacologic approach to identify survival factors responsible for the resistance of melanoma cells to MEK/ERK antagonists. In addition, we describe a new tumor cell-selective means to bypass this resistance in vitro and in vivo. By generating a panel of isogenic cell lines with specific defects in the apoptotic machinery, we found that the ability of melanoma cells to survive in the absence of functional MEK relies on an ERK-independent expression of the antiapoptotic factor Mcl-1 (and to a lesser extent, Bcl-x(L) and Bcl-2). Using computer-based modeling, we developed a novel Bcl-2 homology domain 3 (BH3) mimetic. This compound, named TW-37, is the first rationally designed small molecule with high affinity for Mcl-1, Bcl-x(L), and Bcl-2. Mechanistic analyses of the mode of action of TW-37 showed a synergistic tumor cell killing in the presence of MEK inhibitors. Importantly, TW-37 unveiled an unexpected role of the MAPK pathway in the control of reactive oxygen species (ROS). This function was critical to prevent the activation of proapoptotic functions of p53 in melanoma cells, but surprisingly, it was dispensable for normal melanocytes. Our results suggest that this MAPK-dependent ROS/p53 feedback loop is a point of vulnerability of melanoma cells that can be exploited for rational drug design.
authors.affiliation: Department of Dermatology, University of Michigan Comprehensive Cancer Center, Ann Arbor, MI 48109, USA.
authors.forename: Monique
authors.initials: M
authors.lastname: Verhaegen
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Bauer
authors.forename: Cristina
authors.initials: C
authors.lastname: Martín de la Vega
authors.forename: Guoping
authors.initials: G
authors.lastname: Wang
authors.forename: Keith G
authors.initials: KG
authors.lastname: Wolter
authors.forename: J Chadwick
authors.initials: JC
authors.lastname: Brenner
authors.forename: Zaneta
authors.initials: Z
authors.lastname: Nikolovska-Coleska
authors.forename: Audrey
authors.initials: A
authors.lastname: Bengtson
authors.forename: Rajan
authors.initials: R
authors.lastname: Nair
authors.forename: James T
authors.initials: JT
authors.lastname: Elder
authors.forename: Matt
authors.initials: M
authors.lastname: Van Brocklin
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Carey
authors.forename: Carol R
authors.initials: CR
authors.lastname: Bradford
authors.forename: Shaomeng
authors.initials: S
authors.lastname: Wang
authors.forename: María S
authors.initials: MS
authors.lastname: Soengas
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides / Q000737:chemistry / Q000494:pharmacology*; D002070:Butadienes / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015394:Molecular Structure; D009570:Nitriles / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000235:genetics; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013450:Sulfones / Q000737:chemistry / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D001549:Benzamides; D002070:Butadienes; D009570:Nitriles; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D013450:Sulfones; C515128:TW-37 compound; D016159:Tumor Suppressor Protein p53; C113580:U 0126; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D020928:Mitogen-Activated Protein Kinases