Manganese Superoxide Dismutase Is a Promising Target for Enhancing Chemosensitivity of Basal-like Breast Carcinoma (original) (raw)
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Breast cancer is one of the most common malignancies of all cancers in women worldwide. Many difficulties reside in the prediction of tumor metastatic progression because of the lack of sufficiently reliable predictive biological markers, and this is a permanent preoccupation for clinicians. Manganese superoxide dismutase (MnSOD) may represent a rational candidate as a predictive biomarker of breast tumor metastatic progression, because its gene expression is profoundly altered between early and advanced breast cancer, in contrast to expression in the normal mammary gland. In this review, we report the characterization of some gene polymorphisms and molecular mechanisms of SOD2 gene regulation, which allows a better understanding of how MnSOD is decreased in early breast cancer and increased in advanced breast cancer. Several studies display the biological significance of MnSOD level in proliferation as well as in invasive and angiogenic abilities of breast tumor cells by controlling superoxide anion radical (O 2
2004
The most important cellular protective mechanisms against oxidative stress are antioxidant enzymes. Their action is based on decomposal of reactive oxygen species (ROS) and their transformation to H 2 O 2. Within the mitochondria manganese superoxide dismutase (MnSOD) affords the major defense against ROS. In this study we investigated tissue sections from 101 breast carcinomas for the immunohistochemical expression of MnSOD protein and these results were assessed in relation to various clinicopathological parameters, in order to clarify the prognostic value of this enzyme. The possible relationship to hormone receptor content, anti-apoptotic protein bcl-2, p53 and cell proliferation was also estimated. High expression levels were observed, as 79/101 (78,2%) cases expressed strong immunoreactivity. In this study MnSOD increased in a direct relationship with tumor grade and is therefore inversely correlated with differentiation (p=0.0004). Furthermore, there was a strong positive correlation between MnSOD expression and p53 protein immunoreactivity (p=0.0029). The prognostic impact of MnSOD expression in determining the risk of recurrence and overall survival with both univariate (long-rang test) and multivariate (Cox regression) methods of analysis was statistically not significant. These results indicate that neoplastic cells in breast carcinomas retain their capability to produce MnSOD and thus protected from the possible cellular damage provoked by reactive oxygen species. In addition, MnSOD content varies according to the degree of differentiation of breast carcinoma.
MnSOD/SOD2 in Cancer: The Story of a Double Agent
2018
Manganese-dependent superoxide dismutase (MnSOD/SOD2) is one of the major antioxidant enzymes which scavenges the superoxide produced in the mitochondria, the main source of free radicals in non-pathological conditions. This first barrier is important to prevent early stages of cancer development. However, once the tumor is established, upregulation of MnSOD without a concomitant increase of scavengers of hydrogen peroxide (H2O2) plays a much complex role. It contributes to proliferation, angiogenesis and invasion, affecting glycolytic metabolism and preventing the mitochondria from inducing apoptosis favoring therapy resistance. The increase of H2O2 mediated by MnSODis able to induce phenotypical changes in several tumor types, such as epithelia-mesenchymal transition increasing the motility of tumor cells, neuroendocrine differentiation and senescent secretory phenotypes which feed tumor progression by producing cytokines and growth factors.
Two polymorphic variants of manganese superoxide dismutase (MnSOD), with either Ile or Thr at amino acid 58, (Ile 58 MnSOD or Thr 58 MnSOD), have been found in the human population. The MnSOD activity of these two variants and their effects on the malignant phenotype of human breast cancer MCF-7 cells were compared. It was demonstrated that MnSOD-overexpressing clones obtained from transfection of the two MnSOD cDNAs into MCF-7 cells had increased MnSOD immunoreactive protein and increased MnSOD activity. Cells overexpressing Ile 58 MnSOD had 3-fold higher MnSOD activity than cells overexpressing Thr 58 MnSOD in vivo at an equal MnSOD protein level. Tumor-suppressive effects of MnSOD-overexpressing cells were indicated by: (a) decreased plating efficiency; (b) elongated cell population doubling time; (c) lower clonogenic fraction in soft agar; and (d) complete inhibition or delayed onset of tumor formation in nude mice.
Human manganese superoxide dismutase suppresses HER2/neu-mediated breast cancer malignancy
Febs Letters, 2007
The up-regulation of HER2/neu is associated with human malignancies and is a useful target for developing anticancer drugs. Overexpression of human manganese superoxide dismutase (MnSOD) has been demonstrated to effectively suppress various carcinoma cells, including breast carcinomas, in vitro and in vivo. This study demonstrates that MnSOD effectively suppresses HER2/neu oncogene expression at the transcriptional level. Additionally, stable transfection was
2001
Manganese superoxide dismutase (MnSOD) is a nuclear encoded primary antioxidant enzyme localized in mitochondria. Because expression of MnSOD plays a major role in maintaining cellular redox status and reactive oxygen species are known to play a role in signal transduction and carcinogenesis, we investigated the role of MnSOD in the development of cancer using a two-stage [7,12-dimethylbenz(a)-anthracene plus 12-Otetradecanoylphorbol-13-acetate (TPA)] skin carcinogenesis model. Female transgenic mice expressing the human MnSOD gene in the skin and their nontransgenic counterparts were used in this study. Pathological examination demonstrated significant reduction of papilloma formation in transgenic mice. Quantitative analysis of 4-hydroxy-2-nonenal-modified proteins showed greater accumulation of oxidative damage products in nontransgenic compared with transgenic mice, and this oxidative damage was demonstrated to be present in both mitochondria and nucleus. TPA increased activator protein-1 (AP-1) binding activity within 6 h in nontransgenic mice, but increased AP-1 binding activity was delayed in the transgenic mice. Electrophoretic mobility shift assay, transcription of the target genes, and Western analysis studies indicated that the increased AP-1 binding activity was attributable to induction of the Jun but not the Fos protein families. Overexpression of MnSOD selectively inhibited the TPA-induced activation of protein kinase C⑀ and prevented subsequent activation of c-Jun NH 2 -terminal kinase in response to TPA. Overall, these results indicate that MnSOD regulates both cellular redox status and selectively modulates PKC⑀ signaling, thereby delaying AP-1 activation and inhibiting tumor promotion, resulting in reduction of tumors in MnSOD transgenic mice.
Cell Death & Disease, 2022
Triple-negative breast cancer (TNBC) has been shown with high mitochondrial oxidative phosphorylation and production of reactive oxygen species (ROS). MnSOD (SOD2) is a mitochondrial antioxidant defense that has been implicated in inhibition of human malignancies. However, the impact of MnSOD on immunosuppressive macrophage functions and TNBC aggressiveness has never been explored. We found here that SOD2high is primarily observed in the aggressive subtypes of HER2(+) breast cancers and TNBCs patients. Further analyses demonstrated that the oncoprotein multiple copies in T-cell malignancy-1 (MCT-1 or MCTS1) induces mitochondrial superoxide dismutase (MnSOD) in TNBC cells by stabilizing the transcription factor Nrf2. SOD2high/MCTS1high expression correlates with a poor prognosis in breast cancer patients. MnSOD in TNBC cells functions as a prooxidant peroxidase that increases mitochondrial ROS (mROS) and adaptation to oxidative stress under the oncogenic effect. Interleukin-6 (IL-6) ...
Epigenetic Regulation of Manganese Superoxide Dismutase Expression in Human Breast Cancer Cells
Epigenetics, 2006
Malignant breast cancer cells often exhibit lower expression and activity of manganese superoxide dismutase (MnSOD) than their normal cell counterparts; however, the mechanism(s) responsible for this change remains unclear. We examined whether SOD2, the gene encoding MnSOD, was epigenetically repressed in breast cancer cell lines by DNA methylation and histone acetylation. RT-PCR analysis of SOD2 mRNA showed the nontumorigenic breast epithelial cell line MCF-10A to have two to three fold higher expression levels than either UACC-893 or MDA-MB-435 breast carcinoma cells. Analysis of a region in the SOD2 promoter by sodium bisulfite genomic sequencing demonstrated significantly higher levels of CpG methylation in both human breast carcinoma cell lines assessed than in MCF-10A cells. CREB binding in vitro to a cognate site derived from this region was repressed by DNA methylation, and CREB binding to the 5' regulatory region of the SOD2 gene in vivo as determined by ChIP was significantly lower in breast carcinoma cells than in MCF-10A. Increased cytosine methylation was also accompanied by a significant decrease in the level of acetylated histones in the same region of the SOD2 promoter. Finally, a causal link between cytosine methylation and transcriptional repression was established by increasing MnSOD mRNA, protein and activity in breast carcinoma cells using the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine. These findings indicate that epigenetic silencing of SOD2 constitutes one mechanism leading to the decreased expression of MnSOD observed in many breast cancers.
Journal of Biological Chemistry, 2002
Matrix metalloproteinases (MMPs) participate in cell migration and remodeling processes by affecting the extracellular matrix. MMP-2 is thought to be involved in cancer cell invasiveness. It has been proposed that the activity of MMP-2 can be modulated by intracellular reactive oxygen species (ROS)/reactive nitrogen species. We hypothesized that manganese superoxide dismutase (MnSOD) could mediate MMP-2 activity by changing the intracellular ROS level and that nitric oxide ( ⅐ NO) may be involved in this process. Human breast cancer MCF-7 cells were stably transfected with plasmids containing MnSOD cDNA. A 2-30-fold increase of MnSOD protein and activity was observed in four clones. Our data demonstrated that overexpression of MnSOD stimulated the activation of MMP-2 with a corresponding elevation of ROS. A decrease in ROS by ebselen, a glutathione peroxidase mimetic, or by transduction of adenovirus containing human catalase or glutathione peroxidase cDNA abolished the effect of MnSOD on MMP-2 activation. Treatment of MCF-7 cells with antimycin A or rotenone increased intracellular ROS production and MMP-2 activation simultaneously. Our data also showed a suppression of endothelial nitric-oxide synthase expression that was accompanied by decreased ⅐ NO production in MnSOD-overexpressing cells. However, the changes in endothelial nitric-oxide synthase and ⅐ NO did not correlate with the MnSOD activity. Corresponding changes of
International journal of oncology, 2011
Manganese superoxide dismutase (MnSOD) seems to have a pivotal role in maintaining the normal phenotype by suppressing cell growth through blocking the entrance of quiescent cells into the cell cycle. MnSOD protein expression has been shown to be dysregulated in malignant cells. A well-established experimental breast epithelial cell cancer model was used to observe the relationship in the presence or absence of such protein and the phenotype of the cells. This model was derived from the spontaneously immortalized breast epithelial cell line MCF-10F, which was transformed with estrogen and radiation. The results of this study showed that deleterious expression of MnSOD enhanced the malignant phenotype demonstrated by cell cycle protein expression changes. Thus, the malignant cell line, called Alpha5, which had high levels of MnSOD protein expression, maintained a similar phenotype to the normal cell line MCF-10F. The cell cycle arrest observed in G1 phase of the Alpha5 cell line was ...