Knockdown of protein tyrosine phosphatase SHP-1 inhibits G1/S progression in prostate cancer cells through the regulation of components of the cell-cycle machinery.
SHP-1, a haematopoietic cell-specific tyrosine phosphatase, is also expressed in human prostate. In this study, we report that SHP-1 depletion in PC-3 cells induced by small interfering RNAs causes G1 phase cell-cycle arrest accompanied by changes in some components of the cell-cycle machinery. SHP-1 knockdown increases p27(Kip1) (p27) protein stability, its nuclear localization and p27 gene transcription. These effects could be mediated by PI3K-AKT pathway as SHP-1 interacts with PI3K regulating its activity and p110 catalytic subunit phosphorylation. The increase in p27 protein stability could also because of reduced cyclin-dependent kinase (CDK2) activity. SHP-1 knockdown decreases the CDK6 levels, inducing retinoblastoma protein hypophosphorylation, downregulation of cyclin E and thereby a decrease in the CDK2 activity. However, the codepletion of SHP-1 and p27 does not produce re-entry into the cycle, implying that p27 is not required to maintain cell-cycle arrest induced by SHP-1 depletion. The maintenance of the PC-3 cell anti-proliferative response after p27 loss could be because of mislocalization of CDK2 induced by SHP-1 knockdown. This study shows that SHP-1 depletion promotes cell-cycle arrest by modulating the activity of cell-cycle regulators and suggests that SHP-1 may be required for the proper functioning of events governing cell-cycle progression.
Rodríguez-Ubreva
F J
FJ
Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Alcalá de Henares, E-28871 Madrid, Spain.
Cariaga-Martinez
A E
AE
Cortés
M A
MA
Romero-De Pablos
M
M
Ropero
S
S
López-Ruiz
P
P
Colás
B
B
D015153:Blotting, Western; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000235:genetics / Q000378:metabolism; D051361:Cyclin-Dependent Kinase 6 / Q000235:genetics / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008297:Male; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016196:S Phase
D018797:Cell Cycle Proteins; D019927:Cyclin E; D016160:Retinoblastoma Protein; D050760:Cyclin-Dependent Kinase Inhibitor p27; D008156:Luciferases; C495894:CDK2 protein, human; C495911:CDK6 protein, human; D051357:Cyclin-Dependent Kinase 2; D051361:Cyclin-Dependent Kinase 6; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6