ABSTRACT
OBJECTIVES: Previous studies have suggested the importance of reactive oxygen species in all the steps of carcinogenesis. Antioxidant enzymes are considered as the most specific and efficient way to protect cells from reactive oxygen species. The purpose of the current study was to identify the role of oxidative stress and major antioxidant enzymes in ovarian carcinomas. METHODS: The material consisted of 68 invasive ovarian carcinomas which were studied by immunohistochemistry with antibodies to antioxidant enzymes peroxiredoxins (Prxs) I-VI and thioredoxin and oxidative stress markers nitrotyrosine and 8-hydroxydeoxyguanosine (8-OHdG). Both the intensity and the extent of the stainings were assessed, and the nuclear and cytoplasmic expressions were evaluated separately. RESULTS: The study revealed the hydroxyl radical-derived oxidative stress marker in DNA, 8-OHdG, to be a powerful prognostic factor in ovarian carcinoma (Kaplan-Meier survival log-rank-analysis P = 0.003; risk of death to ovarian carcinoma 2.69; 95% confidence interval 1.35-5.35. 8-OHdG was also associated with poor differentiation (P = 0.053), higher stage (P < 0.001), and non-optimal surgical outcome (P = 0.002). High cytoplasmic Prx IV immunostaining was associated with a better prognosis (P = 0.024), and elevated cytoplasmic expression rates of Prxs V (P = 0.043) and VI (P = 0.032) were associated with a higher stage. CONCLUSIONS: To conclude, it appears that hydroxyl radical-derived oxidative stress, but not nitric oxide radical-derived oxidative stress, plays a significant role in ovarian carcinogenesis. Immunohistochemical assessment of 8-OHdG could provide a useful prognostic marker in ovarian cancer.
Subject(s)
Biomarkers, Tumor/analysis , Carcinoma/diagnosis , DNA Adducts/analysis , Guanine/analogs & derivatives , Ovarian Neoplasms/diagnosis , 8-Hydroxy-2'-Deoxyguanosine/analogs & derivatives , Antioxidants/metabolism , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Carcinoma/genetics , Carcinoma/mortality , Carcinoma/pathology , Cell Nucleus/metabolism , Cell Nucleus/pathology , Cytoplasm/metabolism , Cytoplasm/pathology , DNA Adducts/metabolism , Female , Guanine/analysis , Guanine/metabolism , Humans , Immunohistochemistry/methods , Neoplasm Staging , Ovarian Neoplasms/genetics , Ovarian Neoplasms/mortality , Ovarian Neoplasms/pathology , Oxidative Stress/genetics , Oxidative Stress/physiology , Prognosis , Survival Analysis , Tyrosine/analogs & derivatives , Tyrosine/metabolismABSTRACT
p14(ARF) tumor suppressor protein regulates p53 by interfering with mdm2-p53 interaction. p14(ARF) is activated in response to oncogenic stimuli but little is known of the responses of endogenous p14(ARF) to different types of cellular stress or DNA damage. Azidothymidine (AZT) is being tested in several clinical trials as an enhancer of anticancer chemotherapy. However, the knowledge of the relationship between AZT and cellular pathways, e.g. p53 pathway, is very limited. In this study, we show that AZT, cisplatin (CDDP) and docetaxel (DTX) all induce unique molecular responses in OVCAR-3 ovarian carcinoma cells carrying a mutated p53, while in A2780, ovarian carcinoma and MCF-7 breast carcinoma cells with wild type p53, all of these drugs cause similar p53 responses. We found that endogenous p14(ARF) protein in OVCAR-3 cells is down-regulated by DTX but induced by AZT and a short CDDP pulse treatment. In HT-29 colon carcinoma cells with a mutated p53, all treatments down-regulated p14(ARF) protein. Both CDDP and AZT increased the expression of p14ARF mRNA in OVCAR-3 cells. Differences in cell death induced by these drugs did not explain the differences in protein and mRNA expressions. No increase in the level of either c-Myc or H-ras oncoproteins was seen in OVCAR-3 cells after AZT or CDDP-treatment. These results suggest that p14(ARF) can respond to DNA damage without oncogene activation in cell lines without functional p53.
