Dose-dependent proliferative and cytotoxic effects of melatonin on human epidermoid carcinoma and normal skin fibroblast cells

The evaluation of melatonin and EGF interaction on breast cancer metastasis

OBJECTIVES

Metastasis in breast cancer is the first cause of death in patients. The epidermal growth factor (EGF) increases cancer cells' invasion, and migration. Melatonin's inhibitory effects on various types of cancer were confirmed. This study aimed to investigate whether melatonin could apply its impact through the EGF-related pathways or not.

METHODS

First, MDA-MB-231 and MCF7 cells were cultured, and then melatonin effects on cell viability were determined by MTT assay. Transwell invasion assay was applied to identify the invasiveness of these breast cancer cell lines under treatment of EGF and melatonin. Real-time RT-PCR then investigated the expression of MMP9 and MMP2 in determined groups. Cell proliferation was also assayed under EGF and melatonin treatment using Ki67 assessment by flow cytometry.

RESULTS

The rate of invasion and migration of EGF-treated cells increased in both groups, in which melatonin caused increased invasion by EGF just in MCF7 cells. MMP9 and MMP2 expression increased significantly in both cell lines under EGF treatment, and melatonin increased these genes' expression in both cell lines (p<0.05). EGF increased the MMP9 and MMP2 gene expression, and melatonin increased EGF-induced expression (p<0.05). The EGF reduced the expression of the Ki67 protein in the MCF7 cell line, which was negatively affected by melatonin and EGF. In contrast, along with melatonin, EGF did not affect the proliferation of the MDA-MB-231 cell line.

CONCLUSIONS

The results of this study show that melatonin in the presence of EGF does not show the anti-cancer properties previously described for this substance.

Biomedicine and pharmacotherapeutic effectiveness of combinatorial atorvastatin and quercetin on diabetic nephropathy: An in vitro study

INTRODUCTION

Diabetic nephropathy is a type of kidney disorder that develops as a complication of multifactorial diabetes. Diabetic nephropathy is characterized by microangiopathy, resulting from glucose metabolism, oxidative stress, and changes in renal hemodynamics. This study strived to evaluate the in vitro cytoprotective activity of atorvastatin (ATR), and quercetin (QCT) alone and in combination against diabetic nephropathy.

METHODS

The MTT assay was utilized to analyze the effects of the test compounds on NRK-52E rat kidney epithelial cells. The detection of apoptosis and ability to scavenge free radicals was assessed via acridine orange-ethidium bromide (AO-EB) dual fluorescence staining, and 2,2-diphenyl-1-picrylhydrazyfree assay (DPPH), respectively. The ability of anti-inflammatory effect of the test compounds and western blot analysis against TGF-β, TNF-α, and IL-6 further assessed to determine the combinatorial efficacy.

RESULTS

Atorvastatin and quercetin treatment significantly lowered the expression of TGF-β, TNF-α, and IL-6 indicating the protective role in Streptozotocin-induced nephrotoxicity. The kidney cells treated with a combination of atorvastatin and quercetin showed green fluorescing nuclei in the AO-EB staining assay, indicating that the combination treatment restored cell viability. Quercetin, both alone and in combination with atorvastatin, demonstrated strong DPPH free radical scavenging activity and further encountered an anti-oxidant and anti-inflammatory effect on the combination of these drugs.

CONCLUSION

Nevertheless, there is currently no existing literature that reports on the role of QCT as a combination renoprotective drug with statins in the context of diabetic nephropathy. Hence, these findings suggest that atorvastatin and quercetin may have clinical potential in treating diabetic nephropathy.

Testing the protective effects of cyclodextrins vs. alternariol-induced acute toxicity in HeLa cells and in zebrafish embryos

Alternariol (AOH) is a mycotoxin produced by Alternaria fungi, it appears as a contaminant in tomatoes, grains, and grapes. The chronic exposure to AOH may cause carcinogenic and xenoestrogenic effects. Cyclodextrins (CDs) are cyclic oligosaccharides, they form host-guest complexes with apolar molecules. In this study, the interactions of AOH with CD monomers and polymers were examined employing fluorescence spectroscopy. Thereafter, the protective effects of certain CDs vs. AOH-induced toxicity were investigated on HeLa cells and on zebrafish embryos. Our major observations are the following: (1) Sugammadex forms highly stable complex with AOH (K = 4.8 ×10⁴ L/mol). (2) Sugammadex abolished the AOH-induced toxicity in HeLa cells, while native β-CD did not show relevant protective effect. (3) Each CD tested decreased the AOH-induced mortality and sublethal adverse effects in zebrafish embryos: Interestingly, native β-CD showed the strongest protective impact in this model. (4) CD technology may be suitable to relieve AOH-induced toxicity.

Melatonin activates the Mst1-Nrf2 signaling to alleviate cardiac hypertrophy in pulmonary arterial hypertension

Among pulmonary arterial hypertension (PAH) patients, right ventricular (RV) functioning has been considered a major determining factor for cardiac capacity and survival. However, despite the recognition of the clinical importance for preserving RV functioning, no effective treatments are currently available for RV failure. This study aims to suggest one such possible treatment, through investigating the cardio-protective capabilities of the anti-oxidant, melatonin (Mel), for treating adverse RV remodeling in PAH, along with its underlying mechanisms. Arginine vasopressin induced neonatal rat cardiomyocyte hypertrophy in vitro; in vivo, PAH was induced in rats through intraperitoneal monocrotaline (MCT) injections, and Mel was administered intraperitoneally 24 h prior to MCT. Mel reduced rat cardiomyocyte hypertrophy and mitochondrial oxidative stress in vitro by activating the Mst1-Nrf2 pathway, which were all reversed upon siRNA knockdown of Mst1. Likewise, in vivo, Mel pre-treatment significantly ameliorated MCT-induced deterioration in cardiac function, RV hypertrophy, fibrosis and dilation. These beneficial effects were also associated with Mst1-Nrf2 pathway up regulation and its associated reduction in oxidative stress, as evidenced by the decrease in RV malondialdehyde content. Notably, results from Mel treatment were similar, or even superior, to those obtained from N-acetyl cysteine (NAC), which has already been-confirmed as an anti-oxidative treatment for PAH. By contrast, co-treatment with the Mst1 inhibitor XMU-MP-1 reversed all of those Mel-associated beneficial effects. Our findings thus identified Mel as a potent cardio-protective agent against the onset of maladaptive RV remodeling, through enhancement of the anti-oxidative response via Mst1-Nrf2 pathway activation.

Testing the Protective Effects of Sulfobutylether-Βeta-Cyclodextrin (SBECD) and Sugammadex against Chlorpromazine-Induced Acute Toxicity in SH-SY5Y Cell Line and in NMRI Mice

Chlorpromazine (CPZ) is an antipsychotic drug which can cause several adverse effects and drug poisoning. Recent studies demonstrated that CPZ forms highly stable complexes with certain cyclodextrins (CDs) such as sulfobutylether-β-CD (SBECD) and sugammadex (SGD). Since there is no available antidote in CPZ intoxication, and considering the good tolerability of these CDs even if when administered parenterally, we aimed to investigate the protective effects of SBECD and SGD against CPZ-induced acute toxicity employing in vitro (SH-SY5Y neuroblastoma cells) and in vivo (zebrafish embryo) models. Our major findings and conclusions are the following: (1) both SBECD and SGD strongly relieved the cytotoxic effects of CPZ in SH-SY5Y cells. (2) SGD co-treatment did not affect or increase the CPZ-induced 24 h mortality in NMRI mice, while SBECD caused a protective effect in a dose-dependent fashion. (3) The binding constants of ligand–CD complexes and/or the in vitro protective effects of CDs can help to estimate the in vivo suitability of CDs as antidotes; however, some other factors can overwrite these predictions.

The antioxidant effects of melatonin in blood platelets during exposure to electromagnetic radiation – an in vitro study

Objectives

The article presents the results of an in vitro study aimed at identifying changes in parameters of oxidative stress – concentration of malondialdehyde (MDA), enzymatic activity of superoxide dismutase (SOD-1) and protective antioxidant role of melatonin (MLT) during the exposure of blood platelets to electromagnetic radiation (EMR) emitted by monitors.

Methods

Platelets were exposed to an EMR for 30- and 60 min. generated by monitors (1 kHz frequency, 220 V/m intensity). In each sample the level of SOD-1 activity and concentration of MDA were determined.

Results

The MDA concentration increased significantly after 30-and 60-min. irradiation, as compared to control values (2.53 vs 1.36; 3.64 vs 1.36 nmol/109 blood platelets) and after the addition of MLT it decreased (2.53 vs 1.55; 3.64 vs 1.12 nmol/109 blood platelets). The activity of SOD-1 increased significantly compared to control values after 30 min. and 60 min. of exposure to EMR (1.97vs 0.75; 2.08 vs 0.75 U/g of protein), and significantly decreased after the addition of MLT only in samples exposed for 60 min. (2.08 vs 0.95 U/g of protein).

Discussion

The results demonstrated the possibly negative effect of EMR on oxygen metabolism of blood platelets and indicated a possible protective role of melatonin in this process.

The individual and combined effects of ochratoxin A with citrinin and their metabolites (ochratoxin B, ochratoxin C, and dihydrocitrinone) on 2D/3D cell cultures, and zebrafish embryo models

Ochratoxin A and citrinin are nephrotoxic mycotoxins produced by Aspergillus, Penicillium, and/or Monascus species. The combined effects of ochratoxin A and citrinin have been examined in more studies; however, only limited data are available regarding the co-exposure to their metabolites. In this investigation, the individual toxic effects of ochratoxin A, ochratoxin B, ochratoxin C, citrinin, and dihydrocitrinone were tested as well as the combinations of ochratoxin A with the latter mycotoxins were examined on 2D and 3D cell cultures, and on zebrafish embryos. Our results demonstrate that even subtoxic concentrations of certain mycotoxins can increase the toxic impact of ochratoxin A. In addition, typically additive effects or synergism were observed as the combined effects of mycotoxins tested. These observations highlight that different cell lines (e.g. MDBK vs. MDCK), cell cultures (e.g. 2D vs. 3D), and models (e.g. in vitro vs. in vivo) can show different (sometimes opposite) impacts. Mycotoxin combinations considerably increased miR-731 levels in zebrafish embryos, which is an early marker of the toxicity on kidney development. These results underline that the co-exposure to mycotoxins (and/or mycotoxin metabolites) should be seriously considered, since even the barely toxic mycotoxins (or metabolites) in combinations can cause significant toxicity.

The Effect of Melatonin on OCT4 Expression and Granulosa Cell Growth in Female Mice

Melatonin is mainly secreted by the pineal gland as a neurotransmitter. Moreover, melatonin is also produced by the ovary and plays important roles in female reproduction. However, it is unclear whether melatonin has any effect on the transition from the preantral follicle to the early antral follicle. Octamer-binding transcription factor 4 (OCT4) is important to granulosa cells development, which is regulated by gonadotropin. And these regulations are mediated by the GSK3β/β-catenin pathway via the activated PI3K/Akt signaling. The aim of the present study was to determine the effects and the possible mechanisms of melatonin on ovarian cells development. The results showed that melatonin inhibited granulosa cells development, which was accompanied by the downregulation of OCT4 expression. Meanwhile, melatonin also decreased the expression of p-GSK3β (glycogen synthase kinase 3 beta), p-Akt, β-catenin, and its translocation to the nucleus in granulosa cells. Moreover, melatonin attenuated the effects of FSH in vitro and eCG in vivo on these regulations. In conclusion, this study shows that melatonin inhibits ovarian cell development by downregulating the OCT4 expression level, which is possibly mediated by inhibiting the PI3K/Akt and GSK3β/β-catenin pathway. Melatonin attenuates the effects of gonadotropin on ovarian granulosa cells as a negative regulator.

Effects of 1,25 Dihydroxyvitamin D3 on Human Retinal Pigment Epithelial Cell Lines

PURPOSE

To assess the effects of 1,25 dihydroxyvitamin D₃ (vitamin D₃) either alone or under oxidative damage on human retinal pigment epithelium cell lines.

METHODS

The human retinal pigment epithelial cell lines were pretreated with hydrogen peroxide with different concentrations (100-1000 μM) and durations (4, 12 and 24 h) to determine the appropriate dose. A group of cells were treated with vitamin D₃ alone, and another group of cells were co-treated with different concentrations of (10-100 nM) vitamin D₃ and hydrogen peroxide. Anti-cytotoxic, anti-apoptotic and anti-genotoxic effects of vitamin D₃ on the hydrogen peroxide treated cell line were evaluated. In addition, mitochondrial membrane potentials of treated cell lines were measured.

RESULTS

Vitamin D₃ showed statistically significant anti-cytotoxic effects and increased cell viability in all concentrations (p < 0.001). It has also significantly decreased the intracellular ROS generation at concentrations between 10-60 nM and increased intracellular reactive oxygen species in high doses over 90 nM (p < 0.01). When apoptosis was evaluated, vitamin D₃ caused statistically significant decrease in a dose-dependent manner (p < 0.001). In terms of DNA damage which was caused by oxidative stress, it was observed that vitamin D₃ significantly reduced the damage in a dose-dependent manner (p < 0.001). At the doses of 10-50 nM, vitamin D₃ significantly decreased the mitochondrial membrane potential (p < 0.01).

CONCLUSION

Our study suggests that 1,25 (OH)₂ D3 is capable for alleviating the oxidative damage in ARPE cell lines. With these results, vitamin D is thought to be a therapeutic alternative for the prevention of age-related macular degeneration. This warrants further investigations.

Role and Therapeutic Potential of Melatonin in Various Type of Cancers

Cancer is a large group of diseases and the second leading cause of death worldwide. Lung, prostate, colorectal, stomach, and liver cancers are the most common types of cancer in men, whereas breast, colorectal, lung, cervical, and thyroid cancers are the most common among women. Presently, various treatment strategies, including surgical resection combined with chemotherapy, radiotherapy, nanotherapy, and immunotherapy, have been used as conventional treatments for patients with cancer. However, the clinical outcomes of advanced-stage disease remain relatively unfavorable owing to the emergence of chemoresistance, toxicity, and other undesired detrimental side effects. Therefore, new therapies to overcome these limitations are indispensable. Recently, there has been considerable evidence from experimental and clinical studies suggesting that melatonin can be used to prevent and treat cancer. Studies have confirmed that melatonin mitigates the pathogenesis of cancer by directly affecting carcinogenesis and indirectly disrupting the circadian cycle. Melatonin (MLT) is nontoxic and exhibits a range of beneficial effects against cancer via apoptotic, antiangiogenic, antiproliferative, and metastasis-inhibitory pathways. The combination of melatonin with conventional drugs improves the drug sensitivity of cancers, including solid and liquid tumors. In this manuscript, we will comprehensively review some of the cellular, animal, and human studies from the literature that provide evidence that melatonin has oncostatic and anticancer properties. Further, this comprehensive review compiles the available experimental and clinical data analyzing the history, epidemiology, risk factors, therapeutic effect, clinical significance, of melatonin alone or in combination with chemotherapeutic agents or radiotherapy, as well as the underlying molecular mechanisms of its anticancer effect against lung, breast, prostate, colorectal, skin, liver, cervical, and ovarian cancers. Nonetheless, in the interest of readership clarity and ease of reading, we have discussed the overall mechanism of the anticancer activity of melatonin against different types of cancer. We have ended this report with general conclusions and future perspectives.

Therapeutic targets of cancer drugs: Modulation by melatonin

The biological functions of melatonin range beyond the regulation of the circadian rhythm. With regard to cancer, melatonin's potential to suppress cancer initiation, progression, angiogenesis and metastasis as well as sensitizing malignant cells to conventional chemo- and radiotherapy are among its most interesting effects. The targets at which melatonin initiates its anti-cancer effects are in common with those of a majority of existing anti-cancer agents, giving rise to the notion that this molecule is a pleiotropic agent sharing many features with other antineoplastic drugs in terms of their mechanisms of action. Among these common mechanisms of action are the regulation of several major intracellular pathways including mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK) and protein kinase B (AKT/PKB) signaling. The important mediators affected by melatonin include cyclins, nuclear factor-κB (NF-κB), heat shock proteins (HSPs) and c-Myc, all of which can serve as potential targets for cancer drugs. Melatonin also exerts some of its anti-cancer effects via inducing epigenetic modifications, DNA damage and mitochondrial disruption in malignant cells. The regulation of these mediators by melatonin mitigates tumor growth and invasiveness via modulating their downstream responsive genes, housekeeping enzymes, telomerase reverse transcriptase, apoptotic gene expression, angiogenic factors and structural proteins involved in metastasis. Increasing our knowledge on how melatonin affects its target sites will help find ways of exploiting the beneficial effects of this ubiquitously-acting molecule in cancer therapy. Acknowledging this, here we reviewed the most studied target pathways attributed to the anti-cancer effects of melatonin, highlighting their therapeutic potential.

Melatonin Enhances Palladium-Nanoparticle-Induced Cytotoxicity and Apoptosis in Human Lung Epithelial Adenocarcinoma Cells A549 and H1229

Palladium nanoparticles (PdNPs) are increasingly being used in medical and biological applications due to their unique physical and chemical properties. Recent evidence suggests that these nanoparticles can act as both a pro-oxidant and as an antioxidant. Melatonin (MLT), which also shows pro- and antioxidant properties, can enhance the efficacy of chemotherapeutic agents when combined with anticancer drugs. Nevertheless, studies regarding the molecular mechanisms underlying the anticancer effects of PdNPs and MLT in cancer cells are still lacking. Therefore, we aimed to investigate the potential toxicological and molecular mechanisms of PdNPs, MLT, and the combination of PdNPs with MLT in A549 lung epithelial adenocarcinoma cells. We evaluated cell viability, cell proliferation, cytotoxicity, oxidative stress, mitochondrial dysfunction, and apoptosis in cells treated with different concentrations of PdNPs and MLT. PdNPs and MLT induced cytotoxicity, which was confirmed by leakage of lactate dehydrogenase, increased intracellular protease, and reduced membrane integrity. Oxidative stress increased the levels of reactive oxygen species (ROS), malondialdehyde (MDA), nitric oxide (NO), protein carbonyl content (PCC), lipid hydroperoxide (LHP), and 8-isoprostane. Combining PdNPs with MLT elevated the levels of mitochondrial dysfunction by decreasing mitochondrial membrane potential (MMP), ATP content, mitochondrial number, and expression levels of the main regulators of mitochondrial biogenesis. Additionally, PdNPs and MLT induced apoptosis and oxidative DNA damage due to accumulation of 4-hydroxynonenal (HNE), 8-oxo-2'-deoxyguanosine (8-OhdG), and 8-hydroxyguanosine (8-OHG). Finally, PdNPs and MLT increased mitochondrially mediated stress and apoptosis, which was confirmed by the increased expression levels of apoptotic genes. To our knowledge, this is the first study demonstrating the effects of combining PdNPs and MLT in human lung cancer cells. These findings provide valuable insights into the molecular mechanisms involved in PdNP- and MLT-induced toxicity, and it may be that this combination therapy could be a potential effective therapeutic approach. This combination effect provides information to support the clinical evaluation of PdNPs and MLT as a suitable agents for lung cancer treatment, and the combined effect provides therapeutic value, as non-toxic concentrations of PdNPs and MLT are more effective, better tolerated, and show less adverse effects. Finally, this study suggests that MLT could be used as a supplement in nano-mediated combination therapies used to treat lung cancer.

Idarubicin-bromelain combination sensitizes cancer cells to conventional chemotherapy

Objectives

The primary cytotoxic effects of anticancer drugs like idarubicin, a chemotherapeutic agent, are not limited to neoplastic cells; they also produce similar effects in normal cells. In this study, we hypothesized that the combination of idarubicin-bromelain could make cancer cells more susceptible to cytotoxicity and genotoxicity.

Materials and Methods

To test our hypothesis, the optimal concentrations of idarubicin and bromelain were combined and incubated in the HL-60 cancer cell line and normal human mononuclear leukocytes (PBMC) for 24, 48, and 72 hr. Cytotoxicity and genotoxicity were evaluated by measurement of ATP cell viability test, DNA damage, Caspase-3, Acridine orange/ethidium bromide (AO/EB), and DAPI fluorescent dyes in both cell types.

Results

The combination of idarubicin-bromelain significantly reduced cell proliferation in the more potent HL-60 compared to PBMC in all incubation times (P<0.05). DNA damage and Caspase-3 levels (except for 24 hr) were also higher in the HL-60 cell line in comparison with PBMC and were statistically significant (P<0.05). The percentages of apoptotic images obtained by DAPI and AO / EB morphological examination were increased in both cells, depending on the combination dose.

Conclusion

Based on these results, it can be concluded that idarubicin combined with bromelain produces more cytotoxic effects in low concentrations in comparison with when it was used per se in the HL-60 cells. Conversely, it was found that this combination in PBMC caused less cytotoxicity and less genotoxicity. Taken together, it can be said that this new combination makes cancer cells more sensitive to conventional therapy.

Physiological and Pathological Role of Circadian Hormones in Osteoarthritis: Dose-Dependent or Time-Dependent?

Osteoarthritis (OA), the most common form of arthritis, may be triggered by improper secretion of circadian clock-regulated hormones, such as melatonin, thyroid-stimulating hormone (TSH), or cortisol. The imbalance of these hormones alters the expression of pro-inflammatory cytokines and cartilage degenerative enzymes in articular cartilage, resulting in cartilage erosion, synovial inflammation, and osteophyte formation, the major hallmarks of OA. In this review, we summarize the effects of circadian melatonin, TSH, and cortisol on OA, focusing on how different levels of these hormones affect OA pathogenesis and recovery with respect to the circadian clock. We also highlight the effects of melatonin, TSH, and cortisol at different concentrations both in vivo and in vitro, which may help to elucidate the relationship between circadian hormones and OA.