Dataset Information

MEK2 is sufficient but not necessary for proliferation and anchorage-independent growth of SK-MEL-28 melanoma cells.

ABSTRACT: Mitogen-activated protein kinase kinases (MKK or MEK) 1 and 2 are usually treated as redundant kinases. However, in assessing their relative contribution towards ERK-mediated biologic response investigators have relied on tests of necessity, not sufficiency. In response we developed a novel experimental model using lethal toxin (LeTx), an anthrax toxin-derived pan-MKK protease, and genetically engineered protease resistant MKK mutants (MKKcr) to test the sufficiency of MEK signaling in melanoma SK-MEL-28 cells. Surprisingly, ERK activity persisted in LeTx-treated cells expressing MEK2cr but not MEK1cr. Microarray analysis revealed non-overlapping downstream transcriptional targets of MEK1 and MEK2, and indicated a substantial rescue effect of MEK2cr on proliferation pathways. Furthermore, LeTx efficiently inhibited the cell proliferation and anchorage-independent growth of SK-MEL-28 cells expressing MKK1cr but not MEK2cr. These results indicate in SK-MEL-28 cells MEK1 and MEK2 signaling pathways are not redundant and interchangeable for cell proliferation. We conclude that in the absence of other MKK, MEK2 is sufficient for SK-MEL-28 cell proliferation. MEK1 conditionally compensates for loss of MEK2 only in the presence of other MKK.

SUBMITTER: Lee CS

PROVIDER: S-EPMC3041822 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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MEK2 is sufficient but not necessary for proliferation and anchorage-independent growth of SK-MEL-28 melanoma cells.

Lee Chih-Shia CS Dykema Karl J KJ Hawkins Danielle M DM Cherba David M DM Webb Craig P CP Furge Kyle A KA Duesbery Nicholas S NS Duesbery Nicholas S NS

PloS one 20110218 2

Mitogen-activated protein kinase kinases (MKK or MEK) 1 and 2 are usually treated as redundant kinases. However, in assessing their relative contribution towards ERK-mediated biologic response investigators have relied on tests of necessity, not sufficiency. In response we developed a novel experimental model using lethal toxin (LeTx), an anthrax toxin-derived pan-MKK protease, and genetically engineered protease resistant MKK mutants (MKKcr) to test the sufficiency of MEK signaling in melanoma ...[more]

PMID: 21365009

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Project description:Melanoma tumor antigen p97 or melanotransferrin (MTf) is an iron (Fe)-binding protein with high homology to serum transferrin. MTf is expressed at very low levels in normal tissues and in high amounts in melanoma cells. The over-expression of MTf in tumor cells was hypothesized to assist rapidly proliferating neoplastic cells with their increased Fe requirements. However, our recent characterization of the MTf knockout (MTf -/-) mouse demonstrated that MTf did not have an essential role in Fe metabolism. To understand the function of MTf, we utilized whole-genome microarray analysis to examine the gene expression profile of five models after modulating MTf expression. These models included two new stably transfected MTf hyper-expression models (SK-N-MC neuroepithelioma and LMTK- fibroblasts) and one cell type (SK-Mel-28 melanoma) where MTf was down-regulated by post-transcriptional gene silencing. These findings were compared to alterations in gene expression identified using the MTf -/- mouse. In addition, the changes identified from the gene array data were also assessed in a new model of MTf down-regulation in SK-Mel-2 melanoma cells. In the cell line models, MTf hyper-expression led to increased cellular proliferation, while MTf down-regulation resulted in decreased proliferation. Across all five models of MTf down- and up-regulation, we identified three genes modulated by MTf expression. These included ATP-binding cassette sub-family B member 5 (Abcb5), whose change in expression mirrored MTf down- or up-regulation. In addition, thiamine triphosphatase (Thtpa) and transcription factor 4 (Tcf4) were inversely expressed relative to MTf levels across all five models. The products of these three genes are involved in membrane transport, thiamine phosphorylation and cell proliferation/survival, respectively. This study identifies novel molecular targets directly or indirectly regulated by MTf and potential pathways involved in its function. These molecular targets could be involved, at least in part, to the role of MTf in modulating proliferation. Experiment Overall Design: To prepare a construct capable of generating hairpin siRNA specific for human MTf mRNA, the expression vector, pSilencerâ¢ 3.1-H1 neo (Ambion, Texas, USA) was used. The vector was used to clone transgene of 66-bp that transcribe 19-mer double-stranded hairpin RNAs of the target gene. The transgene were specifically targeted to positions 2031-2049-bp in the MTf gene (Genbank Accession: NM_005929). Transfections of pS-MTf transgenes or pS-scrambled vectors into human SK-Mel-28 melanoma cells were performed with LipofectamineTM 2000 reagent (Invitrogen, Melbourne, Australia). Total RNA was isolated from the cells using TRIzol ReagentÂ® (Sigma-Aldrich) according to the manufacturerâs protocol. Total RNA from the stably-transfected SK-Mel-28 melanoma cell lines were prepared and hybridized onto Human Genome U133 Plus 2.0 Array. The human GeneChipÂ® U133 Plus 2.0 consists of greater than 47,000 transcripts and variants from over 38,500 well characterized human genes (Affymetrix, Santa Clara, CA).

Dataset Information

MEK2 is sufficient but not necessary for proliferation and anchorage-independent growth of SK-MEL-28 melanoma cells.

Publications

MEK2 is sufficient but not necessary for proliferation and anchorage-independent growth of SK-MEL-28 melanoma cells.

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