Human prostate epithelium lacks Wee1A-mediated DNA damage-induced checkpoint enforcement.
Cellular DNA damage triggers the DNA damage response pathway and leads to enforcement of cell cycle checkpoints, which are essential for the maintenance of genomic integrity and are activated in early stages of tumorigenesis. A special feature of prostate cancer is its high incidence and multifocality. To address the functionality of DNA damage checkpoints in the prostate, we analyzed the responses of human primary prostate epithelial cells (HPECs) and freshly isolated human prostate tissues to gamma-irradiation. We find that gamma-irradiation activates the ataxia telangiectasia mutated-associated DNA damage response pathway in the HPECs but that the clearance of phosphorylated histone H2AX (gammaH2AX) foci is delayed. Surprisingly, gamma-irradiated HPECs were unable to enforce cell cycle checkpoint arrest and had sustained cyclin-dependent kinase 2 (Cdk2)-associated kinase activity because of a lack of inhibitory Cdk phosphorylation by Wee1A tyrosine kinase. We further show that HPECs express low levels of Wee1A and that ectopic Wee1A efficiently rescues the checkpoints. We recapitulate the absence of checkpoint responses in epithelium of ex vivo irradiated human prostate tissue despite robust induction of gammaH2AX. The findings show that prostate epithelium has a surprising inability to control checkpoint arrest, the lack of which may predispose to accrual of DNA lesions.
Kiviharju-af Hällström
Taija M
TM
Molecular Cancer Biology Program, Biomedicum Helsinki and Haartman Institute, University of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland.
Jäämaa
Sari
S
Mönkkönen
Mia
M
Peltonen
Karita
K
Andersson
Leif C
LC
Medema
René H
RH
Peehl
Donna M
DM
Laiho
Marikki
M
D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle / Q000528:radiation effects; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000528:radiation effects; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology / Q000528:radiation effects; D004848:Epithelium / Q000201:enzymology* / Q000528:radiation effects; D006801:Humans; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism*; D019000:Phosphotyrosine / Q000378:metabolism; D011467:Prostate / Q000166:cytology / Q000201:enzymology* / Q000528:radiation effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011839:Radiation, Ionizing; D015398:Signal Transduction / Q000528:radiation effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; C499349:WEE1 protein, human; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2