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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
16
pubmed:dateCreated
2006-8-16
pubmed:abstractText
The Ini1 subunit of the SWI/SNF chromatin remodeling complex suppresses formation of malignant rhabdoid tumors in humans and mice. Transduction of Ini1 into Ini1-deficient tumor-derived cell lines has indicated that Ini1 arrests cell growth, controls chromosomal ploidy, and suppresses tumorigenesis by regulating components of the retinoblastoma (Rb) signaling pathway. Furthermore, conditional inactivation of Ini1 in mouse fibroblasts alters the expression of various Rb-E2F-regulated genes, indicating that endogenous Ini1 levels may control Rb signaling in cells. We have reported previously that loss of one allele of Ini1 in mouse fibroblasts results only in a 15% to 20% reduction in total Ini1 mRNA levels due to transcriptional compensation by the remaining Ini1 allele. Here, we examine the effects of Ini1 haploinsufficiency on cell growth and immortalization in mouse embryonic fibroblasts. In addition, we examine pituitary tumorigenesis in Rb-Ini1 compound heterozygous mice. Our results reveal that heterozygosity for Ini1 up-regulates cell growth and immortalization and that exogenous Ini1 down-regulates the growth of primary cells in a Rb-dependent manner. Furthermore, loss of Ini1 is redundant with loss of Rb function in the formation of pituitary tumors in Rb heterozygous mice and leads to the formation of large, atypical Rb(+/-) tumor cells lacking adrenocorticotropic hormone expression. These results confirm in vivo the relationship between Rb and Ini1 in tumor suppression and indicate that Ini1 plays a role in maintaining the morphologic and functional differentiation of corticotrophic cells.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
1538-7445
pubmed:author
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
66
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8076-82
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Functional interaction of the retinoblastoma and Ini1/Snf5 tumor suppressors in cell growth and pituitary tumorigenesis.
pubmed:affiliation
Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural