Abstract
Metallothioneins (MTs) are a group of metal-binding proteins involved in cell proliferation, differentiation and apoptosis. The MT-2A isoform is generally the most abundant isoform among the 10 known functional MT genes. In the present study, we observed that down-regulation of the MT-2A gene in MCF-7 cells via siRNA-mediated silencing inhibited cell growth by inducing cell cycle arrest in G1-phase (G1-arrest) and a marginal increase in cells in sub-G1-phase. Scanning electron microscopic examination of the cells with silenced expression of MT-2A (siMT-2A cells) revealed essentially normal cell morphology with presence of scattered apoptotic cells. To elucidate the underlying molecular mechanism, we examined the expression of cell cycle related genes in MT-2A-silenced cells and found a higher expression of the ataxia telangiectasia mutated (ATM) gene concomitant with a lower expression of the cdc25A gene. These data suggest that MT-2A could plausibly modulate cell cycle progression from G1- to S-phase via the ATM/Chk2/cdc25A pathway.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Ataxia Telangiectasia Mutated Proteins
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Blotting, Western
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Breast Neoplasms / genetics*
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Breast Neoplasms / metabolism
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Cell Cycle / genetics*
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Cell Cycle Proteins / biosynthesis*
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Cell Cycle Proteins / genetics
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Cell Line, Tumor
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Cell Proliferation
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Checkpoint Kinase 2
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DNA-Binding Proteins / biosynthesis*
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DNA-Binding Proteins / genetics
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Down-Regulation
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Female
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Flow Cytometry
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G1 Phase / genetics
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Gene Expression
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Gene Silencing
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Humans
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Metallothionein / genetics*
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Microscopy, Electron, Scanning
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Protein Serine-Threonine Kinases / biosynthesis*
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Protein Serine-Threonine Kinases / genetics
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RNA, Messenger / analysis
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RNA, Small Interfering
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Reverse Transcriptase Polymerase Chain Reaction
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S Phase / genetics
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Signal Transduction / genetics*
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Tumor Suppressor Proteins / biosynthesis*
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Tumor Suppressor Proteins / genetics
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cdc25 Phosphatases / biosynthesis*
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cdc25 Phosphatases / genetics
Substances
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Cell Cycle Proteins
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DNA-Binding Proteins
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RNA, Messenger
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RNA, Small Interfering
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Tumor Suppressor Proteins
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Metallothionein
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Checkpoint Kinase 2
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ATM protein, human
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Ataxia Telangiectasia Mutated Proteins
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CHEK2 protein, human
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Protein Serine-Threonine Kinases
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CDC25A protein, human
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cdc25 Phosphatases