Checkpoint effectors CDKN1A and Gadd45 correlate with oxidative DNA damage in human prostate carcinoma.
BACKGROUND
Although cellular oxidative stress is a major cause of DNA damage, it is still not clear to what degree it affects genetic instability and malignant progression in established prostate carcinoma (PCa).


METHODS
We examined the expression of CDKN1A and Gadd45 proteins acting on cell cycle checkpoints and DNA repair in PCa relative to the presence of oxidative DNA damage, as measured by the detection of the DNA adduct 8-hydroxy-2-deoxyguanosine (8-OHdG.). Sixteen PCa and 28 benign prostate hyperplasias (BPH) were analyzed. RT-PCR was used to evaluate WAF1 and Gadd45 transcripts. Western blot and ELISA were used to analyze proteins and 8-OHdG adducts. Proliferation was studied by Ki67 image cytometry; telomerase activity was detected by TRAP- ELISA.


RESULTS
Multivariate factor analysis provided evidence that, in PCa, DNA checkpoint proteins were associated with 8-OHdG and did not prevent neoplastic cells proliferation. Conversely, in BPH, oxidative DNA damage was inversely correlated with DNA checkpoint proteins and proliferation, suggesting the presence of energy-depleted senescent cells.


CONCLUSIONS
Although in non-malignant tissue extensive oxidative DNA damage drives cells to a metabolic blockage, in PCa neoplastic cells it activates repair mechanisms favoring the escape from senescence and the expansion of DNA-damaged clones.
Giovannini
Catia
C
Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi University Hospital, Via Massarenti 9, 40138 Bologna, Italy.
Chieco
Pasquale
P
Bertaccini
Alessandro
A
Gramantieri
Laura
L
Lacchini
Michela
M
Martorana
Giuseppe
G
D000368:Aged; D000369:Aged, 80 and over; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000096:biosynthesis* / Q000235:genetics; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004249:DNA Damage / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D000097642:GADD45 Proteins
D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D009687:Nuclear Proteins; D012333:RNA, Messenger; C493956:CDKN1A protein, human; C439070:GADD45A protein, human; D000097642:GADD45 Proteins