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PMID:17344214

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Citation

Saxena, NK, Vertino, PM, Anania, FA and Sharma, D (2007) leptin-induced growth stimulation of breast cancer cells involves recruitment of histone acetyltransferases and mediator complex to CYCLIN D1 promoter via activation of Stat3. J. Biol. Chem. 282:13316-25

Abstract

Numerous epidemiological studies documented that obesity is a risk factor for breast cancer development in postmenopausal women. Leptin, the key player in the regulation of energy balance and body weight control also acts as a growth factor on certain organs in both normal and disease state. In this study, we analyzed the role of leptin and the molecular mechanism(s) underlying its action in breast cancer cells that express both short and long isoforms of leptin receptor. Leptin increased MCF7 cell population in the S-phase of the cell cycle along with a robust increase in CYCLIN D1 expression. Also, leptin induced Stat3-phosphorylation-dependent proliferation of MCF7 cells as blocking Stat3 phosphorylation with a specific inhibitor, AG490, abolished leptin-induced proliferation. Using deletion constructs of CYCLIN D1 promoter and chromatin immunoprecipitation assay, we show that leptin induced increase in CYCLIN D1 promoter activity is mediated through binding of activated Stat3 at the Stat binding sites and changes in histone acetylation and methylation. We also show specific involvement of coactivator molecules, histone acetyltransferase SRC1, and mediator complex in leptin-mediated regulation of CYCLIN D1 promoter. Importantly, silencing of SRC1 and Med1 abolished the leptin induced increase in CYCLIN D1 expression and MCF7 cell proliferation. Intriguingly, recruitment of both SRC1 and Med1 was dependent on phosphorylated Stat3 as AG490 treatment inhibited leptin-induced recruitment of these coactivators to CYCLIN D1 promoter. Our data suggest that CYCLIN D1 may be a target gene for leptin mediated growth stimulation of breast cancer cells and molecular mechanisms involve activated Stat3-mediated recruitment of distinct coactivator complexes.

Links

PubMed PMC2923657 Online version:10.1074/jbc.M609798200

Keywords

Acetylation/drug effects; Antineoplastic Agents/pharmacology; Breast Neoplasms/epidemiology; Breast Neoplasms/etiology; Breast Neoplasms/metabolism; Cell Line, Tumor; Chromatin Immunoprecipitation; Cyclin D; Cyclins/metabolism; Endodeoxyribonucleases/metabolism; Female; Histone Acetyltransferases/metabolism; Histones/metabolism; Humans; Leptin/metabolism; Leptin/pharmacology; Methylation/drug effects; Obesity/complications; Obesity/epidemiology; Obesity/metabolism; Postmenopause/metabolism; Promoter Regions, Genetic; Protein Modification, Translational/drug effects; S Phase/drug effects; STAT3 Transcription Factor/metabolism; Tyrphostins/pharmacology

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

HUMAN:CCND1

involved_in

GO:0044321: response to leptin

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:LEP

involved_in

GO:0051726: regulation of cell cycle

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:LEP

involved_in

GO:0046427: positive regulation of receptor signaling pathway via JAK-STAT

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:LEP

involved_in

GO:0044320: cellular response to leptin stimulus

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:STAT3

involved_in

GO:0051726: regulation of cell cycle

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:STAT3

involved_in

GO:0044320: cellular response to leptin stimulus

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:STAT3

involved_in

GO:0033210: leptin-mediated signaling pathway

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:STAT3

involved_in

GO:0044321: response to leptin

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:STAT3

enables

GO:0031490: chromatin DNA binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

HUMAN:STAT3

involved_in

GO:0006355: regulation of transcription, DNA-templated

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:STAT3

enables

GO:0003700: DNA-binding transcription factor activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

Notes

See also

References

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