Cell cycle checkpoint defects contribute to genomic instability in PTEN deficient cells independent of DNA DSB repair.
Chromosomes in PTEN deficient cells display both numerical as well as structural alterations including regional amplification. We found that PTEN deficient cells displayed a normal DNA damage response (DDR) as evidenced by the ionizing radiation (IR)-induced phosphorylation of Ataxia Telangiectasia Mutated (ATM) as well as its effectors. PTEN deficient cells also had no defect in Rad51 expression or DNA damage repair kinetics post irradiation. In contrast, caffeine treatment specifically increased IR-induced chromosome aberrations and mitotic index only in cells with PTEN, and not in cells deficient for PTEN, suggesting that their checkpoints were defective. Furthermore, PTEN-deficient cells were unable to maintain active spindle checkpoint after taxol treatment. Genomic instability in PTEN deficient cells could not be attributed to lack of PTEN at centromeres, since no interaction was detected between centromeric DNA and PTEN in wild type cells. These results indicate that PTEN deficiency alters multiple cell cycle checkpoints possibly leaving less time for DNA damage repair and/or chromosome segregation as evidenced by the increased structural as well as numerical alterations seen in PTEN deficient cells.
Gupta
Arun
A
Washington University School of Medicine, St. Louis, MO, USA.
Yang
Qin
Q
Pandita
Raj K
RK
Hunt
Clayton R
CR
Xiang
Tao
T
Misri
Sandeep
S
Zeng
Sicong
S
Pagan
Julia
J
Jeffery
Jessei
J
Puc
Janusz
J
Kumar
Rakesh
R
Feng
Zhihui
Z
Powell
Simon N
SN
Bhat
Audesh
A
Yaguchi
Tomoko
T
Wadhwa
Renu
R
Kaul
Sunil C
SC
Parsons
Ramon
R
Khanna
Kum Kum
KK
Pandita
Tej K
TK
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins; D002110:Caffeine / Q000494:pharmacology; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002869:Chromosome Aberrations; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D042822:Genomic Instability; D006801:Humans; D007259:Infrared Rays; D007621:Karyotyping; D051059:PTEN Phosphohydrolase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D016615:Telomere / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D002110:Caffeine; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D051135:Rad51 Recombinase; D051059:PTEN Phosphohydrolase; D017239:Paclitaxel