Zinc Protoporphyrin Regulates Cyclin D1 Expression Independent of Heme Oxygenase Inhibition
Division of Neonatology, Children's Hospital of Philadelphia, PA 19104, USA. Journal of Biological Chemistry
(Impact Factor: 4.57).
10/2009; 284(52):36302-11. DOI: 10.1074/jbc.M109.031641
Zinc protoporphyrin IX (ZnPP), an endogenous heme analogue that inhibits heme oxygenase (HO) activity, represses tumor growth. It can also translocate into the nucleus and up-regulate heme oxygenase 1 (HMOX1) gene expression. Here, we demonstrate that tumor cell proliferation was inhibited by ZnPP, whereas tin protoporphyrin (SnPP), another equally potent HO-1 inhibitor, had no effect. Microarray analysis on 128 tumorigenesis related genes showed that ZnPP suppressed genes involved in cell proliferation and angiogenesis. Among these genes, CYCLIN D1 (CCND1) was specifically inhibited as were its mRNA and protein levels. Additionally, ZnPP inhibited CCND1 promoter activity through an Sp1 and Egr1 overlapping binding site (S/E). We confirmed that ZnPP modulated the S/E site, at least partially by associating with Sp1 and Egr1 proteins rather than direct binding to DNA targets. Furthermore, administration of ZnPP significantly inhibited cyclin D1 expression and progression of a B-cell leukemia/lymphoma 1 tumor in mice by preferentially targeting tumor cells. These observations show HO independent effects of ZnPP on cyclin D1 expression and tumorigenesis.
Available from: Stuart Lind
- "While induction of HO-1 in normal cells is cytoprotective and antiinflammatory [73,74], expression of HO-1 in cancer cells may support malignant growth  and render cancer cells more resistant to chemotherapy . In fact, HO-1 has been proposed as a potential cellular target for cancer therapy , and HO-1 inhibitors such as zinc protoporphyrin have been reported to suppress cancer growth in vitro and in vivo   . Therefore, the combination of DHA and HO- 1 inhibitors could be an attractive approach to more effectively suppress cancer growth, and future work to investigate this potential combinatorial approach is justified. "
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ABSTRACT: The effect of DHA on HO-1 expression in cancer cells has never been characterized. This study examines DHA-induced HO-1 expression in human cancer cell model systems. DHA enhanced HO-1 gene expression in a time- and concentration-dependent manner, with maximal induction at 21 hours of treatment. This induction of HO-1 expression was confirmed in vivo using a xenograft nude mouse model fed a fish oil-enriched diet. The increase in HO-1 gene transcription induced by DHA was significantly attenuated by the antioxidant N-Acetyl Cysteine (NAC), suggesting the involvement of oxidative stress. This was supported by direct measurement of lipid peroxide levels after DHA treatment. Using a human HO-1 gene promoter reporter construct, we identified two antioxidant response elements (AREs) that mediate the DHA-induced increase in HO-1 gene transcription. Knockdown of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression compromised the DHA-induced increase in HO-1 gene transcription, indicating the importance of the Nrf2 pathway in this event. However, the protein levels of Nrf2 remained unchanged upon DHA treatment. Further studies demonstrated that DHA reduces nuclear Bach1 protein expression by promoting its degradation and attenuates Bach1 binding to the AREs in the HO-1 gene promoter. In contrast, DHA enhanced Nrf2 binding to the AREs without affecting nuclear Nrf2 expression levels, indicating a new cellular mechanism that mediates DHA’s induction of HO-1 gene transcription. To our knowledge, this is the first characterization of DHA induced HO-1 expression in human malignant cells.
The Journal of nutritional biochemistry 05/2014; 25(5). DOI:10.1016/j.jnutbio.2013.12.011 · 3.79 Impact Factor
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ABSTRACT: Historically, oxidative stress was recognized to contribute to cancer development uniquely by induction of genomic instability. However, recent research has provided multiple evidence that reactive oxygen species and other free radicals, such as nitric oxide, often produced at elevated levels within tumor tissue, may function as signaling molecules that initiate and/or modulate the different regulatory pathways involved in tumorigenesis and metastasis. This review will focus on the complex role of oxidative stress and redox signaling in cancer neovascularization, a process without which the tumor is unable to grow beyond few millimeters in size. Reactive oxygen species and nitric oxide affect cell responses to hypoxia, a major trigger of angiogenic switch in tumors and are important upstream regulators as well as downstream mediators of action of the most potent proangiogenic factor - vascular endothelial growth factor. We will discuss targeting the redox-regulated mechanisms for antiangiogenic anticancer therapy and focus on recent developments in small-molecule agents that have either completed clinical trials or show a great promise to be subjected to them. Modulation of redox species production, signaling and metabolism and/or manipulating cellular antioxidant responses represents a multitargeted therapeutic approach which may possibly overcome the limitations of single-agent antiangiogenic treatments and potentiate effects of standard methods.
Current pharmaceutical design 12/2010; 16(35):3877-94. DOI:10.2174/138161210794454969 · 3.45 Impact Factor
Available from: Halina Was
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ABSTRACT: Heme oxygenase-1 (HO-1) degrades heme to carbon monoxide (CO), biliverdin, and ferrous iron. As HO-1 expression is highly increased by stressful conditions, the major role of the enzyme is the protection against oxidative injury. Additionally, it regulates cell proliferation, modulates inflammatory response and facilitates angiogenesis. Beneficial activities of HO-1 have been recognized in many pathological states e.g. atherosclerosis, diabetes, ischemia/reperfusion injury or organ transplantation. Interestingly HO-1 expression is very often boosted in tumor tissues and could be further elevated in response to radio-, chemo-, or photodynamic therapy. A growing body of evidence suggests that HO-1 may play a role in tumor induction and can potently improve the growth and spread of tumors. This review discusses the implications of HO-1 properties for tumor proliferation and cell death, differentiation, angiogenesis and metastasis, and tumor-related inflammation. Finally, it suggests that pharmacological agents that regulate HO activity or HO-1 gene silencing may become powerful tools for preventing the onset or progression of various cancers and sensitize them to anticancer therapies.
Current drug targets 12/2010; 11(12):1551-70. DOI:10.2174/1389450111009011551 · 3.02 Impact Factor
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