BMP2 exposure results in decreased PTEN protein degradation and increased PTEN levels.
The tumour suppressor gene PTEN encodes a dual-specificity phosphatase that recognizes protein and phosphatidylinositiol substrates and modulates cellular functions such as migration and proliferation. Germline mutations of PTEN have been shown to cause Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome and Proteus syndrome. Recently, germline mutations in BMPR1A, the gene encoding the type 1A receptor of bone morphogenetic proteins (BMP) have been found in rare families with Cowden syndrome, suggesting that there may be a link between BMP signaling and PTEN. We thus sought to determine whether BMP2 stimulation alters PTEN protein levels in the breast cancer line, MCF-7. We found that exposure to BMP2 increased PTEN protein levels in a time- and dose-dependent manner. The increase in PTEN protein was rapid and was not due to an increase in new protein synthesis, as cycloheximide treatment did not inhibit BMP2-induced PTEN accumulation, suggesting that BMP2 stimulation inhibited PTEN protein degradation. Indeed, we found that BMP2 treatment of MCF-7 cells decreased the association of PTEN with two proteins in the degradative pathway, UbCH7 and UbC9. These data indicate that BMP2 exposure can regulate PTEN protein levels by decreasing PTEN's association with the degradative pathway. This opens up a new mode of regulating PTEN activity to be investigated further and may explain why BMPR1A can act as a minor susceptibility gene for PTEN mutation negative Cowden syndrome.
Waite
Kristin A
KA
Clinical Cancer Genetics Program, Comprehensive Cancer Center, Division of Human Genetics, Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA.
Eng
Charis
C
D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2; D052005:Bone Morphogenetic Protein Receptors, Type I; D019485:Bone Morphogenetic Proteins / Q000235:genetics* / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism; D002455:Cell Division; D002465:Cell Movement; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D020022:Genetic Predisposition to Disease; D006801:Humans; D008025:Ligases / Q000378:metabolism; D009154:Mutation; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D017978:Receptors, Growth Factor / Q000235:genetics; D013577:Syndrome; D013997:Time Factors; D016212:Transforming Growth Factor beta; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011500:Protein Synthesis Inhibitors; D017978:Receptors, Growth Factor; D016212:Transforming Growth Factor beta; D025521:Tumor Suppressor Proteins; D003513:Cycloheximide; C079437:UBE2L3 protein, human; D044763:Ubiquitin-Conjugating Enzymes; D017346:Protein Serine-Threonine Kinases; C498211:BMPR1A protein, human; D052005:Bone Morphogenetic Protein Receptors, Type I; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D008025:Ligases; D000098843:Ubiquitin-Conjugating Enzyme UBC9