Linked Life Data

18519679

Source:http://linkedlifedata.com/resource/pubmed/id/18519679

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
2008-6-3
pubmed:abstractText
Mel-18, a polycomb group (PcG) protein, has been suggested as a tumor suppressor in human breast cancer. Previously, we reported that Mel-18 has antiproliferative activity in breast cancer cells. However, its functional mechanism has not been fully elucidated. Here, we investigated the role of Mel-18 in human breast cancer. We saw an inverse correlation between Mel-18 and phospho-Akt, which were expressed at low and high levels, respectively, in primary breast tumor tissues from 40 breast cancer patients. The effect of Mel-18 on cell growth was examined in two breast cancer cell lines, SK-BR-3 and T-47D, which express relatively low and high levels of endogenous Mel-18, respectively. On Mel-18 overexpression in SK-BR-3 cells, cell growth was attenuated and G(1) arrest was observed. Likewise, suppression of Mel-18 by antisense expression in T-47D cells led to enhanced cell growth and accelerated G(1)-S phase transition. In these cells, cyclin-dependent kinase (Cdk)-4 and Cdk2 activities were affected by Mel-18, which were mediated by changes in cyclin D1 expression and p27(Kip1) phosphorylation at Thr(157), but not by INK4a/ARF genes. The changes were both dependent on the phosphatidylinositol 3-kinase/Akt signaling pathway. Akt phosphorylation at Ser(473) was reduced by Mel-18 overexpression in SK-BR-3 cells and enhanced by Mel-18 suppression in T-47D cells. Akt-mediated cytoplasmic localization of p27(Kip1) was inhibited by Mel-18 in SK-BR-3 cells. Moreover, Mel-18 overexpression showed reduced glycogen synthase kinase-3beta phosphorylation, beta-catenin nuclear localization, T-cell factor/lymphoid enhancer factor promoter activity, and cyclin D1 mRNA level. Taken together, we established a linear relationship between Mel-18-->Akt-->G(1) phase regulators.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1538-7445
pubmed:author
pubmed:issnType
Electronic
pubmed:day
1
pubmed:volume
68
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4201-9
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Mel-18 negatively regulates INK4a/ARF-independent cell cycle progression via Akt inactivation in breast cancer.
pubmed:affiliation
Department of Pathology, College of Medicine, Hanyang University, Seoul, Republic of Korea.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't