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Molecolar Oncology, Markers, Clinical Correlates |
Department of Pathology, University of Oulu and Oulu University Hospital, 90014 Oulu, Finland [P. K., A. M., Y. S.]; The Center for Cell Signaling Research and Division of Molecular Life Sciences, Ewha Womans University, Seoul 120-750, Korea [S. W. K.]; and Department of Medicine, Division of Pulmonary Medicine, University of Helsinki and Helsinki University Hospital, 00014 Helsinki and Department of Internal Medicine, University of Oulu and Oulu University Hospital, 90014 Oulu, Finland [V. L. K.]
| ABSTRACT |
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Experimental Design: We examined immunohistochemically a large set of samples from patients with breast carcinoma and investigated associations with parameters such as tumor-node-metastasis classification, hormone receptor status, and patient survival. Three biopsies of healthy breast tissue were used as controls.
Results: Expression of peroxiredoxins I, III, IV, and V was found in
80% of cases, whereas the expression of Prx II and VI was less frequent. Increased expression of Prx III was found to associate with the presence of progesterone (P = 0.02) and estrogen (P = 0.03) receptors, and Prxs IV (P = 0.009) and VI (P = 0.04) were overexpressed in progesterone receptor positive cases. Prx V was the only isoform that associated with items of tumor-node-metastasis classification, it was connected to a larger tumor size (P = 0.05) and positive lymph node status (P = 0.04). Prx V positivity was also connected with shorter survival (P = 0.04), whereas Prxs III (P = 0.002) and IV (P = 0.02) were related to better prognosis, probably resulting from their connection with a positive hormone receptor status.
Conclusions: In conclusion, we found that expression of peroxiredoxins, especially III, IV and V, is increased in breast malignancy, suggesting the induction of Prxs as response to increased production of reactive oxygen species in carcinomatous tissue.
| INTRODUCTION |
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From prokaryotes to primates, cells have developed different kinds of reparative or defensive systems to combat toxic processes of ROS. These defense systems include antioxidant enzymes such as superoxide dismutases, catalase, glutathione peroxidases, and a quite recently found, rapidly growing family of peroxiredoxins (7 , 8) . Although for example catalase is located only in peroxisomes and decomposes hydrogen peroxide to molecular oxygen and water, peroxiredoxins are present in various cellular compartments and reduce peroxides to the corresponding alcohol (or water), just like the other peroxidases (9, 10, 11) . However, Prx family has some special features compared with the other peroxidases. They act both as the peroxidase and the cosubstrate because when reducing H2O2, Prxs themselves are oxidized (10) . Then Prxs are reduced mainly by thioredoxin, except for Prx VI, the electron donor of which is not known yet. Instead of having heme or selenocysteine, as with many other peroxidases, peroxiredoxins have cysteine(s) as their active site. In Prxs IIV, which have two conserved cysteines and belong therefore to 2-Cys subgroup, the NH2-terminal Cys-SH group has been shown to be the primary site of oxidation and when oxidized, it rapidly reacts with another conserved cysteine in COOH terminus to form an intermolecular disulfide bond (12) . Prx I and II are cytosolic proteins, whereas Prx III is present in mitochondria and Prx IV in endoplasmic reticulum and lysosomes but is also secreted to extracellular space (7 , 13) . Peroxiredoxin VI has only one conserved cysteine, and it is the only member of 1-Cys peroxiredoxin subgroup and is found as the highest concentrations in lung tissue (14, 15, 16) . Prx V has been classified to atypical 2-Cys subgroup and its catalytic site represents a special case among the Prx isoforms, and it has been speculated that Prx V could be more effective against ROS compared with other Prxs (17 , 18) . Moreover, Prx V is subcellularly located to peroxisomes and mitochondria to places where protection against ROS is mostly needed.
There is fastly growing evidence that oxidative stress is important not only for normal cell physiology but also for many pathological processes like atherosclerosis, neurodegenerative diseases, allergies, and cancer (3 , 19, 20, 21) . ROS participate in carcinogenesis in all its stages, e.g., initiation, promotion, and progression (3) . Elevated O2- levels have been measured in breast cancer, and ·OH modification has been discovered to rise up to 17-fold over normal breast tissue in invasive ductal carcinoma (1 , 22) . It is still uncertain whether this is attributable to increased DNA damage by ROS or diminished DNA repair enzyme activity. There is also epidemiological evidence between oxidative stress and cancer; the protective role of antioxidants against cancer development has been demonstrated (23) . Also, high intake of transition metals such as iron, which enhances the production of ROS, has been shown to accelerate tumor induction (24) . Nevertheless, the connection between peroxiredoxins and breast cancer has not yet been properly studied (25) .
In this study, we examined a large set of breast carcinomas for the immunohistochemical expression of peroxiredoxin isoforms IVI in breast cancer tissue. The results were correlated with known clinical and biochemical parameters of the tumors such as TNM stage, estrogen and progesterone receptor status, proliferation, and survival.
| MATERIALS AND METHODS |
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Immunohistochemistry.
The polyclonal Prx antibodies have been described previously (7
, 14
, 27
, 28)
. Specimens were first sectioned (thickness, 4 µm), then deparaffinized in xylene and rehydrated through descending ethanol series. Then they were immersed in 10 mM citric acid monohydrate (pH 6.0) for 10 min, boiled in a microwave oven at 850 W for 2 min and at 350 W for 8 min. After that, primary antibodies were incubated on the slides for 1 h with a dilution of 1:1500 for Prx I, 1:1000 for Prx II, 1:500 for Prx III, 1:1000 for Prx IV, and 1:2000 for Prxs V and VI. The immunostaining was done using the Histostain-Plus Bulk Kit (Zymed Laboratories, Inc., South San Francisco, CA). The same procedure was used to generate negative control sections except that primary antibodies were replaced by PBS and serum isotype controls (Zymed Laboratories, Inc.).
The immunostaining results were evaluated semiquantitatively by dividing the staining reaction into four categories: - = no immunostaining present; + = weak immunostaining; ++ = moderate immunostaining; and +++ = strong immunostaining.
Cell proliferation was studied with a monoclonal mouse antihuman Ki-67 antibody (Zymed Laboratories Inc.). The dilution used was 1:50. The immunostaining was performed as described above, except that avidin-biotin-peroxidase complex method was used and 3,3'-diaminobenzidine was as the chromogen. The results were evaluated as percentage of positive cells of the whole cell population.
The presence or abundance of the estrogen and progesterone receptors was also studied immunohistochemically as above. The dilution for both was 1:100 (Novocastra Laboratories Ltd., Newcastle upon Tyne, United Kingdom). In each case, the percentage of positively stained nuclei was evaluated and then a percentage of positively stained tumor cells for estrogen and progesterone receptors were obtained. CerBb2-immunostaining was performed as Prxs, and a mouse monoclonal antibody was used for the immunostaining (Novocastra Laboratories Ltd.). Dilution used was 1:500.
Statistical Analysis.
SPSS 10.1.4 for Windows (Chicago, IL) was used for statistical analysis. The significance of the associations was determined using Fishers exact probability test, t test, and Cox multivariate regression analysis. In survival analysis, Kaplan-Meier curve was used, and the significance was measured by the log-rank, Breslow, and Tarone-Ware tests. Probability values P
0.05 were considered significant.
| RESULTS |
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2 cm in greatest dimension) or large tumor size (T2T4, >2 cm) and N categories as lymph node negative (N0) or lymph node positive (N1N3) groups. Grading was distributed into two subgroups: 0 = well or moderately differentiated and 1 = poorly differentiated. Prx I was the only peroxiredoxin isoform that did not have significant association with any clinicopathological parameter studied. Neither Prx II showed any statistical association with the tumor size or the presence of either lymph node or other metastases, but according to histopathological grading, at least moderate expression tended to be associated with poorly differentiated tumors, although not significantly (P = 0.07). However, Prxs III (P = 0.03), IV (P = 0.03), and V (P = 0.03) showed significantly increased expression in poorly differentiated tumors.
We discovered that tumor size associates with the augmented extent of staining of Prx V, alone among the Prx isoforms. When Prx V expression was at least moderate, there was significantly increased risk to tumors size being T2 or more (>2 cm in greatest dimension; P = 0.05). However, no relationship between other Prxs expression, and tumor size was observed. Prx V was the only isoform to have increased expression in the lymph node metastasis-positive cases (P = 0.04). We found no significant associations between the presence of distant metastases and Prx staining.
There was a significant relationship between the expression of Prx III and Prx IV (P = 0.00003) and between Prx III and VI (P = 0.002). In addition, the connection between Prx III and Prx V was near significant (P = 0.07). No associations between cell proliferation and Prx immunostaining could be found, although there were near-significant associations between Prx II and Ki-67 (P = 0.09). Neither was proto-oncogene CerbB2 overexpression related to any Prx expression.
When investigating association between Prx isoforms and hormone receptor status, we observed that augmented expression of Prx III was linked with increased presence of both estrogen (P = 0.03) and progesterone (P = 0.02) receptors. Stronger Prx IV-immunostaining associated with the positivity of progesterone receptors (P = 0.009) but not with estrogen receptors. The presence of Prx VI showed also positive association with progesterone receptors the P being 0.04 but not with estrogen receptors. We found no association between the staining of Prx isoforms I, II, and V and the existence of either hormone receptor. The associations between peroxiredoxin IVI expression and studied clinicopathological parameters are shown in Table 2
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| DISCUSSION |
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In previous studies, TNM classification and pathological changes have been attempted to connect with Prx I expression in breast and other tumors (25 , 29 , 31) . In oral squamous cell carcinoma, Yanagawa et al. (31) found low Prx I expression levels to be associated with larger tumor masses, lymph node metastases, and poorly differentiated tumors. Nevertheless, we didnt find any correlation with any clinicopathological features and Prx I expression in breast carcinoma, which is also in line with the study of Noh et al. (25) . Instead, we found that expression of Prxs III, IV, and V was significantly stronger when tumors were poorly differentiated or separately with Prx V when tumors were larger or had lymph node metastases. It has previously been demonstrated in vitro that Prx genes IIV are overexpressed when H2O2 concentration in cells is elevated (32) , and, on the other hand, peroxisomes and mitochondria have been reported to be the two major intracellular sources of ROS, including H2O2 (33) . These observations are in line with our results that specifically expressions of Prx IIIV, which are subcellularly located near these places, were pronounced in most malignant tumors. Prx III is the only isoform that is located only in mitochondria, Prx IV is present in lysosomes and extracellularly, but it is also found in the proximity of mitochondria, whereas Prx V is compartmentalized to both peroxisomes and mitochondria (9 , 11 , 12) . Moreover Prx III has been localized particularly in the vicinity of mitochondrial degeneration, and it has been hypothesized that this could be because of induction of Prx III by oxidative stress (11) . Taken together, this suggests that in malignant breast tumors, production of H2O2 increases especially in peroxisomes and mitochondria, and cells respond to impending oxidative stress by increasing Prx levels near these areas.
Noh et al. (25) have previously presented that overexpression of Prxs IIII in breast cancer could be explained by the antiapoptotic and proliferative effects of these proteins. Therefore, another possible explanation for increased Prx levels in larger tumors would be that they are a result of Prxs antiapoptotic features that provide growth advantage to tumor cells. There are several studies on antiapoptotic effects of Prxs I and II (34 , 35) , and it is apparent that ROS cause apoptosis (36) . Thus, it is probable that also other Prx isoforms are able to inhibit H2O2-mediated physiological apoptosis, cause abnormal proliferation, and thereby may lead to tumorigenesis. However, in our material, only expression of Prx V was associated with tumor size and furthermore, we did not find any relationship between cell proliferation and Prx expression.
Increased expression of Prxs I and II has been previously marginally and Prx V significantly connected to longer patient survival in malignant mesothelioma (11) . In line with this, we found that the expression of Prx III and IV were associated with a better prognosis of the patients. Prxs did not, however, have independent prognostic significance. Prx III tended to have increased expression in cells with positive progesterone and estrogen receptor status and Prx IV overexpressed in progesterone receptor-positive cells. As is well known, positive hormone receptor status correlates with longer survival. This might be one reason for the association of these Prxs with a better survival, but it still remains unclear why increased Prx III and IV expressions are associated with the presence of hormone receptors. In addition, Prx VI was also overexpressed in progesterone receptor-positive tumors, but it was not associated with any other parameters, including survival. Connections between the extent of staining of Prx III and Prxs IV and VI can probably be explained by tendency of these isoforms to overexpress in progesterone receptor-positive cases, corresponding association between Prx III and Prx VI has been previously found also in malignant mesothelioma (11) .
By contrast, increased expression of Prx V was associated with larger tumor size, positive lymph node status, poor differentiation, and a shorter patient survival (mean survival declined from 185 to 140 months) when staining was divided in either positive or negative. Logically, with Prx III and IV, expression of Prx V was independent from hormone receptor status, and this gives support to our hypothesis that longer survival in Prx III and IV overexpressive cases may be secondary to their association with hormone receptors, not necessarily suggesting a direct role between Prx expression and survival. Relationship between hormone receptor status and Prxs IIII has been studied earlier in a small set of breast cancers without finding significant associations (25) .
In summary, our study demonstrated expression of all Prx isoforms in breast cancer tissue. It has been previously suggested that high Prx levels in cancer may be because of proliferative and antiapoptotic functions that may participate in tumorigenesis. Nevertheless, we found that especially mitochondrial and peroxisomal Prx isoforms, Prxs IIIV, were overexpressed in the most malignant tumors and this, together with our other results showing no correlation between Prx and cell proliferation, suggests the induction of these proteins by oxidative stress. In addition, ubiquitous nature of Prxs, divergent subcellular locations, and overexpression in variety of diseases related to ROS all support high physiological importance and protective function of Prxs, although overwhelmed by elevated H2O2 levels of breast cancer. Additional investigations are needed also to reveal mechanisms how increased Prx III and IV levels are connected with positive hormone receptor status and probably thereby longer survival.
| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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1 Sources of research support: Sigrid Juselius Foundation and the Cancer Society of Finland. ![]()
2 To whom requests for reprints should be addressed, at University of Oulu, Department of Pathology, P. O. Box 5000 (Aapistie 5), 90014 Oulu, Finland. Phone: 358-8-5375948; Fax: 358-8-5375953; E-mail: msoini{at}cc.oulu.fi ![]()
3 The abbreviations used are: ROS, reactive oxygen species; TNM, tumor-node-metastasis; Prx, peroxiredoxin. ![]()
Received 10/23/02; revised 3/20/03; accepted 4/14/03.
| REFERENCES |
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. J. Biol. Chem., 273: 6297-6302, 1998.
B activation. J. Biol. Chem., 272: 30952-30961, 1997.This article has been cited by other articles:
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![]() |
J.-H. Kim, P. N. Bogner, S.-H. Baek, N. Ramnath, P. Liang, H.-R. Kim, C. Andrews, and Y.-M. Park Up-Regulation of Peroxiredoxin 1 in Lung Cancer and Its Implication as a Prognostic and Therapeutic Target Clin. Cancer Res., April 15, 2008; 14(8): 2326 - 2333. [Abstract] [Full Text] [PDF] |
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P. Karihtala, Y. Soini, P. Auvinen, R. Tammi, M. Tammi, and V.-M. Kosma Hyaluronan in Breast Cancer: Correlations With Nitric Oxide Synthases and Tyrosine Nitrosylation J. Histochem. Cytochem., December 1, 2007; 55(12): 1191 - 1198. [Abstract] [Full Text] [PDF] |
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Y. Fujita, T. Nakanishi, M. Hiramatsu, H. Mabuchi, Y. Miyamoto, A. Miyamoto, A. Shimizu, and N. Tanigawa Proteomics-Based Approach Identifying Autoantibody against Peroxiredoxin VI as a Novel Serum Marker in Esophageal Squamous Cell Carcinoma. Clin. Cancer Res., November 1, 2006; 12(21): 6415 - 6420. [Abstract] [Full Text] [PDF] |
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L. True, I. Coleman, S. Hawley, C.-Y. Huang, D. Gifford, R. Coleman, T. M. Beer, E. Gelmann, M. Datta, E. Mostaghel, et al. A molecular correlate to the Gleason grading system for prostate adenocarcinoma PNAS, July 18, 2006; 103(29): 10991 - 10996. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. T. Lehtonen, P. M. H. Markkanen, M. Peltoniemi, S. W. Kang, and V. L. Kinnula Variable overoxidation of peroxiredoxins in human lung cells in severe oxidative stress Am J Physiol Lung Cell Mol Physiol, May 1, 2005; 288(5): L997 - L1001. [Abstract] [Full Text] [PDF] |
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