[Show abstract][Hide abstract] ABSTRACT: Mutations of the PPP2R1B gene, which encodes the Abeta scaffolding subunit of serine/threonine protein phosphatase 2A (PP2A), have been identified in several types of cancer including lung and breast carcinoma. One of these mutations results in an alteration of glycine 90 to aspartic acid (G90D), which has been found in both tumor and genomic DNA, raising the possibility that it is associated with an increased risk for cancer. A novel microarray-based technology was used to screen for this single-nucleotide polymorphism in 387 cancer patients and 329 control individuals. These data were used for case-control and family-based comparisons in order to study the association of this polymorphism with susceptibility to lung carcinoma, breast carcinoma, and acute lymphoblastic leukemia. The frequency of the G90D polymorphism in breast cancer patients was significantly higher in cases (3%) than in controls (0.3%). The wild-type Abeta subunit interacted with the B56gamma (PPP2R5C), PR72 (PPP2R3A), and PR48 subunits of PP2A but did not interact with the B55alpha (PPP2R2A), B56alpha (PPP2R5A), or B56beta (PPP2R5B) regulatory subunits in an in vitro binding assay. The G90D alteration inhibited the interaction of Abeta with the B56gamma subunit but had no effect on binding to the PR72 subunit. These results provide evidence that the G90D alteration of the Abeta subunit of PP2A is associated with a low frequency of breast carcinoma and that the role of this alteration in transformation is likely to involve decreased interaction with the B56gamma regulatory subunit.
Genes Chromosomes and Cancer 03/2006; 45(2):182-90. · 3.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The PPP2R1B gene, which encodes the β isoform of the A subunit of the serine/threonine protein phosphatase 2A (PP2A), was identified
as a putative human tumor suppressor gene. Sequencing of thePPP2R1B gene, located on human chromosome 11q22-24, revealed somatic alterations in 15% (5 out of 33) of primary lung tumors, 6%
(4 out of 70) of lung tumor–derived cell lines, and 15% (2 out of 13) of primary colon tumors. One deletion mutation generated
a truncated PP2A-Aβ protein that was unable to bind to the catalytic subunit of the PP2A holoenzyme. The PP2R1B gene product may suppress tumor development through its role in cell cycle regulation and cellular growth control.