Zinc ion dyshomeostasis increases resistance of prostate cancer cells to oxidative stress via upregulation of HIF1α

Assessing the effect of selenium on cyclin D1 level and nuclear factor kappa b activity in NIH/3T3 fibroblast cells at 2100 MHz electromagnetic field exposure

Although there are numerous studies on the health impacts of electromagnetic field (EMF) of mobile phone operation frequency 2100 MHz, the published works present contradicting results. Long-term exposure to mobile phone frequencies has unclear health hazards. Therefore, it is important to investigate the molecular mechanism of possible biological effects in mobile phone exposure and to determine the corresponding biological markers. Towards this end, this study was designed to assess the effect of 200 nM selenium (Se) on cell viability% [trypan blue], cell cycle biomarker [cyclin D1] and the transcription factor [nuclear factor kappa b (NF-κB)] in NIH/3T3 fibroblast cells when exposed to 2100 MHz mobile phone frequency. When 2100 MHz EMF was exposed to NIH/3T3 fibroblast cells, the cell viability% was reduced, whereas cyclin D1 level and NF-kB activity increased. Also we show that Se supplementation decreases the effects of 2100 MHz EMF on these parameters. Although future studies will be required to investigate the biological effects of EMF emitted by mobile phones, the results obtained here provide an insight into the molecular mechanisms and specifically underlying selenium's protective effect against 2100 MHz EMF exposure.

Zinc affects nuclear factor kappa b and DNA methyltransferase activity in C3H cancer fibroblast cells induced by a 2100 MHz electromagnetic field

The use of mobile phones is becoming widespread with the development of technology, and as a result, its effects on human health are becoming more and more important every day. Studies have reported that the electromagnetic field (EMF) emitted by mobile phones may have adverse effects on the biological systems. In order to evaluate the effect of zinc (Zn) on C3H cancer fibroblast cells exposed to 2100 MHz EMF, we analyzed cell viability%, nuclear factor kappa b (NF-κB) and DNA methyltransferase (DNMT) activities. Cells were divided to following groups: Control, sham control, 2100 MHz EMF, 50 µM Zn + 2100 MHz EMF, 100 µM Zn + 2100 MHz EMF, and 200 µM Zn + 2100 MHz EMF for 2 h. We measurement cell viability, NF-κB and DNMT activities. There was increased cell viability % in the 2100 MHz EMF group compared to the control group, while the cell viability % was decreased in the 50, 100 and 200 µM Zn + 2100 MHz EMF groups compared to 2100 MHz EMF. NF-κB and DNMT activities were a significant increase in the 2100 MHz EMF group compared to the control group, although were statistically decreased in the 50, 100 and 200 µM Zn + 2100 MHz EMF groups compared to the 2100 MHz EMF group. Our results demonstrate that 2100 MHz EMF exposure in cancer fibroblast cells induce NF-κB and DNMT activities, whereas zinc supplementation reduce NF-κB and DNMT activities-induced 2100 MHz EMF.

Zinc is an essential element for the maintenance of redox homeostasis and cell cycle in murine auditory hair cells

A nutrition deficiency is one of the various causes of hearing loss. Zinc is an essential element for cell proliferation, antioxidant reactions, and the maintenance of hearing ability. Our previous studies have reported that the auditory brainstem response (ABR) threshold is increased in mice fed with zinc-deficient diets. However, the molecular mechanism of zinc involved in auditory system remains to be elucidated. In the present study, we examined the detrimental effects of zinc deficiency on cell cycle progression in murine auditory cells (HEI-OC1). The treatment of HEI-OC1 cells with 0.5 μM TPEN (N,N,N',N'-Tetrakis (2-pyridylmethyl) ethylenediamine) for 24 h inhibited cell proliferation, accumulation of reactive oxygen species (ROS), and induction of apoptosis. The cell proliferation block was caused by a G1/S phase arrest. Supplementation of the cell growth medium with 5 μM ZnCl₂ after exposure to TPEN attenuated ROS accumulation and the arrest caused by the zinc deficiency. The ABR threshold was elevated in mice fed with a zinc-deficient diet. Additionally, we observed an increased expression of p21 and decreased expression of cyclin E and pRb in the spiral ganglion (SG), the organ of Corti (OC), Limbus (L), and stria vascularis (SV) in the zinc-deficient mouse cochlea. These results indicated that zinc is an essential nutrient for proliferation via the cell cycle and that a dysregulation of the cell cycle may cause hearing loss.

Sensors for diagnosis of prostate cancer: Looking beyond the prostate specific antigen

Prostate cancer represents one of the most common forms of cancer affecting men across the globe. Due to late diagnosis of this disease, the mortality of this condition is very high. Conventional diagnostic methods like the direct rectal examination are uncomfortable and, in most cases, delayed, and further confirmation is required with biopsies and Gleason score. The most common biomarker approved by the FDA (United States Food and Drug Administration) is the prostate specific antigen (PSA) that is detected by conventional biochemical assays which require expensive reagents, is time-consuming and more often is only indicative and cannot be considered confirmative as it is susceptible to erroneous conclusions. The prostate health index employs quantification of PSA in its free and bound forms to enumerate the risk of prostate cancer and has found acceptance with clinicians though the methods used to determine these quantities are slow and require additional sensitivity. Search for novel biomarkers other than PSA has resulted in the identification of several promising candidates. However, their detection is still heavily dependent upon conventional biochemical assays that retain the challenges of being time-consuming, poorly sensitive and expensive. Development of specific sensor technologies integrating nanomaterials offers a viable alternative for rapid and sensitive determination of these non-PSA markers. This review summarizes the major advances in the development of sensors for diagnosis of prostate cancer using non-PSA markers. It also highlights some of the emerging paradigms in cancer diagnosis that may transform the diagnostic field in the context of prostate cancer.

HIF-1α-Mediated Mitophagy Determines ZnO Nanoparticle-Induced Human Osteosarcoma Cell Death both In Vitro and In Vivo

Although ZnO nanoparticles (NPs) can kill human osteosarcoma cells, the underlying upstream regulatory mechanisms remain unclear. Since hypoxia inducible factor-1α (HIF-1α) regulates the tumor microenvironment, here we explored the interplay between HIF-1α regulation and mitophagy in ZnO NP-induced osteosarcoma inhibition both in vivo and in vitro. We found that ZnO NPs upregulated HIF-1α protein levels when they killed four common human osteosarcoma cell lines. This finding was consistent with our observations that additional HIF-1α upregulation by a hypoxia inducer CoCl₂ or under a 1% hypoxia environment enhanced NP-induced cell death, but concurrent HIF-1α suppression by a hypoxia inhibitor YC-1 or HIF-1α siRNA inhibited NP-induced cell death. We discovered an interplay between HIF-1α and the autophagy-Zn²⁺-reactive oxygen species (ROS)-autophagy cycle axis and revealed that NP-induced cancer cell killing followed a HIF-1α-BNIP3-LC3B-mediated mitophagy pathway. We confirmed that NP-upregulated HIF-1α protein expression was attributed to prolyl hydroxylase inhibition by both ROS and Zn²⁺. In addition, the in vivo assay confirmed the therapeutic effectiveness and safety of ZnO NPs on a nude mice osteosarcoma model. Collectively, our findings clarified the upstream regulatory mechanism of autophagy induced by the NPs and further demonstrated their antitumor ability in vivo. This work provides new targets and strategies for enhancing NP-based osteosarcoma treatment.

Concentration-Dependent Effects of Zinc Sulfate on DU-145 Human Prostate Cancer Cell Line: Oxidative, Apoptotic, Inflammatory, and Morphological Analyzes

Zinc takes part in several of cellular signaling pathways, containing defense against free radicals, apoptosis, and inflammation. However, interaction between zinc and prostate cancer progression is poorly understood. Therefore, zinc treatment in DU-145 human prostate cancer cells was investigated. First, zinc sulfate (ZnSO₄) concentrations with antiproliferative effect were determined using MTT assay. Then, ZnSO₄-induced oxidative damage was evaluated by malondialdehyde (MDA) levels, glutathione (GSH) levels, total oxidant status (TOS) levels, and total antioxidant status (TAS) levels. Apoptotic effects of ZnSO₄ were determined by measuring biochemical and immunohistochemical parameters including caspase 3 (CASP3), cytochrome C (CYC), Bcl-2-associated X protein (Bax), and B cell CLL/lymphoma 2 (Bcl-2) levels. Inflammatory effects of ZnSO₄ were investigated by measuring interleukin-6 (IL-6) levels and tumor necrosis factor-alpha (TNF-α) levels. Finally, morphological analysis was performed using hematoxylin-eosin staining. We found that ZnSO₄ caused a concentration-dependent increase in oxidative stress, apoptosis, and inflammation pathways. Moreover, there were a number of morphological alterations in treated cells depending on the ZnSO₄ concentration. Consequently, our data showed that zinc acts as a regulator of increased oxidative damage and apoptosis through the upregulation of TNF-α and IL-6.

Growth Modulatory Role of Zinc in Prostate Cancer and Application to Cancer Therapeutics

Zinc is a group IIB heavy metal. It is an important regulator of major cell signaling pathways in most mammalian cells, functions as an antioxidant and plays a role in maintaining genomic stability. Zinc deficiency leads to severe diseases in the brain, pancreas, liver, kidneys and reproductive organs. Zinc loss occurs during tumor development in a variety of cancers. The prostate normally contains abundant intracellular zinc and zinc loss is a hallmark of the development of prostate cancer development. The underlying mechanism of this loss is not clearly understood. The knowledge that excess zinc prevents the growth of prostate cancers suggests that zinc-mediated therapeutics could be an effective approach for cancer prevention and treatment, although challenges remain. This review summarizes the specific roles of zinc in several cancer types focusing on prostate cancer. The relationship between prostate cancer and the dysregulation of zinc homeostasis is examined in detail in an effort to understand the role of zinc in prostate cancer.

The Protective Effect of Zinc Against Liver Ischaemia Reperfusion Injury in a Rat Model of Global Ischaemia

BACKGROUND

Ischaemia-reperfusion injury (IRI) is a major obstacle during liver transplantation and resection surgeries for cancer, with a need for effective and safe drugs to reduce IRI. Zinc preconditioning has been shown to protect against liver IRI in a partial (70%) ischaemia model. However, its efficacy against a clinically relevant Pringle manoeuvre that results in global liver ischaemia (100%) is unknown.

AIMS

The aim of this study was to test the efficacy of zinc preconditioning in a rat model of global liver ischaemia.

METHODS

Rats were preconditioned via subcutaneous injection of 10 mg/kg of ZnCl₂, 24 h and 4 h before ischaemia. Total liver ischaemia (100%) was induced by placing a clamp across the portal triad for 30 min. Liver injury was assessed by serum alanine transaminase (ALT) and aspartate transaminase (AST) levels in blood taken before ischaemia (baseline) and at 1, 2, 4, 24, 48, 72, 96 and 120 hours after ischaemia. Animals were culled after 7 days, and the harvested livers were histologically analysed.

RESULTS

On a two-way repeated-measures analysis of variance, there was a statistically significant (p = 0.025) difference in the mean ALT levels between saline- and ZnCl₂-treated groups. Specifically at 24 h after ischaemia, the ALT (341 ± 99 U/L) and AST (606 ± 78 U/L) in the zinc-treated group were significantly less than the ALT (2863 ± 828 U/L) and AST (3591 ± 948 U/L) values in the saline-treated group. Zinc significantly reduced neutrophil infiltration and necrosis compared with the saline control.

CONCLUSION

Zinc preconditioning reduces the overall hepatocellular damage from IRI. These results lay the foundation to assess the benefit of zinc preconditioning for clinical applications.

Why is it worth testing the ability of zinc to protect against ischaemia reperfusion injury for human application

Ischaemia (interruption in the blood/oxygen supply) and subsequent damage induced by reperfusion (restoration of blood/oxygen supply) ultimately leads to cell death, tissue injury and permanent organ dysfunction. The impact of ischaemia reperfusion injury (IRI) is not limited to heart attack and stroke but can be extended to patients undergoing surgeries such as partial nephrectomy for renal cancer, liver resection for colorectal cancer liver metastasis, cardiopulmonary bypass, and organ transplantation. Unfortunately, there are no drugs that can protect organs against the inevitable peril of IRI. Recent data show that a protocol incorporating specific Zn formulation, dosage, number of dosages, time of injection, and mode of Zn delivery (intravenous) and testing of efficacy in a large preclinical sheep model of IRI strongly supports human trials of Zn preconditioning. No doubt, scepticism still exists among funding bodies and research fraternity on whether Zn, a naturally occurring metal, will work where everything else has failed. Therefore, in this article, we review the conflicting evidence on the promoter and protector role of Zn in the case of IRI and highlight factors that may help explain the contradictory evidence. Finally, we review the literature related to the knowledge of Zn's mechanism of action on ROS generation, apoptosis, HIF activation, inflammation, and signal transduction pathways, which highlight Zn's likelihood of success compared to various other interventions targeting IRI.