Paradoxical effects of statins on endothelial and cancer cells: the impact of concentrations.

In addition to their lipid-lowering functions, statins elicit additional pleiotropic effects on apoptosis, angiogenesis, inflammation, senescence, and oxidative stress. Many of these effects have been reported in cancerous and noncancerous cells like endothelial cells (ECs), endothelial progenitor cells (EPCs) and human umbilical vein cells (HUVCs). Not surprisingly, statins' effects appear to vary largely depending on the cell context, especially as pertains to modulation of cell cycle, senescence, and apoptotic processes. Perhaps the most critical reason for this discordance is the bias in selecting the applied doses in various cells. While lower (nanomolar) concentrations of statins impose anti-senescence, and antiapoptotic effects, higher concentrations (micromolar) appear to precipitate opposite effects. Indeed, most studies performed in cancer cells utilized high concentrations, where statin-induced cytotoxic and cytostatic effects were noted. Some studies report that even at low concentrations, statins induce senescence or cytostatic impacts but not cytotoxic effects. However, the literature appears to be relatively consistent that in cancer cells, statins, in both low or higher concentrations, induce apoptosis or cell cycle arrest, anti-proliferative effects, and cause senescence. However, statins' effects on ECs depend on the concentrations; at micromolar concentrations statins cause cell senescence and apoptosis, while at nonomolar concentrations statins act reversely.

Protective and therapeutic effectiveness of taurine supplementation plus low calorie diet on metabolic parameters and endothelial markers in patients with diabetes mellitus: a randomized, clinical trial.

BACKGROUND: Taurine supplementation as a sulfur-containing amino acid may attenuate and/or alleviate diabetes-induced complications and endothelial dysfunction via its anti-inflammatory and antioxidant activities. Our purpose was to investigate the effect of Taurine supplementation on endothelial dysfunction markers, oxidative stress, inflammation, and glycemic control in patients with type 2 diabetes mellitus (T2DM). METHODS: In the current clinical trial, 120 patients with T2DM were randomly allocated to take either Taurine (containing 1 g Taurine, n = 60) or placebo (n = 60) three times per day for an eight-week period. Moreover, all patients were on a low-calorie diet. The primary outcome was fasting blood glucose (FBG) and endothelial markers including sera intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule (VCAM), and matrix metallopeptidase 9 (MMP-9). The secondary outcome was dietary intake, anthropometric indices, serum insulin and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), total antioxidant capacity (TAC), tumor necrosis factor (TNF), high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and lipid profile. RESULTS: After 8 weeks, Taurine-supplemented patients had a considerable decrease in serum insulin and HOMA-IR compared to placebo group. However, Taurine supplementation did not improve other metabolic parameters including lipid profiles, glycated hemoglobin, and fasting blood glucose (FBG). There was a significant decline in MDA, TNF, and hs-CRP levels after these eight-week period of Taurine supplementation. In addition, the Taurine group had fewer serum levels of endothelial dysfunction markers than the placebo group. CONCLUSIONS: The evidence from our study revealed that Taurine supplementation significantly reduced insulin and HOMA-IR, as well as oxidative stress, inflammation, and endothelial markers in individuals with T2DM. Trial registration The protocol of the study was recorded in the Iranian Registry of Clinical Trials (IRCT20180712040438N3).

Quercetin Augments Cisplatin-Induced Apoptosis, DNA Damage Response, and MiR-22 Expression While It Prevents DNA Repair in Osteosarcoma Cells.

BACKGROUND: Osteosarcoma (OS) patients are commonly treated with chemotherapeutic agents like cisplatin (Cis). Quercetin with fewer side effects can improve the potency of chemotherapy and be used in combinational therapies. Herein, we aimed to evaluate the effects of Cis plus quercetin on DNA damage response (DDR), DNA repair, and apoptosis in Saos-2 cells. METHODS: The effects of Cis and quercetin single or in combination on Saos-2 cell viability and the cytotoxicity of the drugs were measured by MTT assay. The expression of DDR and repair components including P53, ATM, ATR, RAD51, and H2AX, and also miR-22 were analyzed by real-time PCR. The rate of apoptosis was measured by flow cytometry. RESULTS: Quercetin potentiated the cytotoxic effects of Cis in Saos-2 cells. The IC50 of Cis reduced from 6.12 µM to 4.25 µM. The combination of quercetin and Cis was associated with the up-regulation of miR-22 and DDR components, including P53, ATM, ATR, and H2AX as well as the down-regulation of RAD51. Moreover, this combined regimen significantly induced apoptosis in Saos-2 cells compared to mono drugs. CONCLUSION: The co-treatment of quercetin and Cis can accelerate DNA damage, DNA damage response, and apoptosis while interfering with the DNA repair process in Saos-2 cells. Moreover, this combination provokes the tumor suppressor miR-22 expression in these cells.

DNA damage response signaling pathways as important targets for combination therapy and chemotherapy sensitization in osteosarcoma.

Osteosarcoma (OS) is the most common bone malignancy that occurs most often in young adults, and adolescents with a survival rate of 20% in its advanced stages. Nowadays, increasing the effectiveness of common treatments used in OS has become one of the main problems for clinicians due to cancer cells becoming resistant to chemotherapy. One of the most important mechanisms of resistance to chemotherapy is through increasing the ability of DNA repair because most chemotherapy drugs damage the DNA of cancer cells. DNA damage response (DDR) is a signal transduction pathway involved in preserving the genome stability upon exposure to endogenous and exogenous DNA-damaging factors such as chemotherapy agents. There is evidence that the suppression of DDR may reduce chemoresistance and increase the effectiveness of chemotherapy in OS. In this review, we aim to summarize these studies to better understand the role of DDR in OS chemoresistance in pursuit of overcoming the obstacles to the success of chemotherapy.

Circulating microRNAs as predictive biomarkers of coronary artery diseases in type 2 diabetes patients.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is an increasing metabolic disorder mostly resulting from unhealthy lifestyles. T2DM patients are prone to develop heart conditions such as coronary artery disease (CAD) which is a major cause of death in the world. Most clinical symptoms emerge at the advanced stages of CAD; therefore, establishing new biomarkers detectable in the early stages of the disease is crucial to enhance the efficiency of treatment. Recently, a significant body of evidence has shown alteration in miRNA levels associate with dysregulated gene expression occurring in T2DM and CAD, highlighting significance of circulating miRNAs in early detection of CAD arising from T2DM. Therefore, it seems crucial to establish a link between the miRNAs prognosing value and development of CAD in T2DM. AIM: This study provides an overview on the alterations of the circulatory miRNAs in T2DM and various CADs and consider the potentials of miRNAs as biomarkers prognosing CADs in T2DM patients. MATERIALS AND METHODS: Literature search was conducted for miRNAs involved in development of T2DM and CAD using the following key words: "miRNAs", "Biomarker", "Diabetes Mellitus Type 2 (T2DM)", "coronary artery diseases (CAD)". Articles written in the English language. RESULT: There has been shown a rise in miR-375, miR-9, miR-30a-5p, miR-150, miR-9, miR-29a, miR-30d, miR-34a, miR-124a, miR-146a, miR-27a, and miR-320a in T2DM; whereas, miR-126, miR-21, miR-103, miR-28-3p, miR-15a, miR-145, miR-375, miR-223 have been shown to decrease. In addition to T2DM, some miRNAs such as mirR-1, miR-122, miR-132, and miR-133 play a part in development of subclinical aortic atherosclerosis associated with metabolic syndrome. Some miRNAs increase in both T2DM and CAD such as miR-1, miR-132, miR-133, and miR-373-3-p. More interestingly, some of these miRNAs such as miR-92a elevate years before emerging CAD in T2DM. CONCLUSION: dysregulation of miRNAs plays outstanding roles in development of T2DM and CAD. Also, elevation of some miRNAs such as miR-92a in T2DM patients can efficiently prognose development of CAD in these patients, so these miRNAs can be used as biomarkers in this regard.

Comparison of the accuracy of fixture-level implant impressions using two different materials for splinting.

Background. Various materials are used for splinting impression copings, the most common of which are auto-polymerizing resins. In this study, a new light-curing pattern resin (Jig-Gel) was investigated and compared with auto-polymerizing resins using two different splinting methods. Methods. After taking impressions with two different materials, a digital caliper with an accuracy of 0.01 mm was used for splinting and measuring the distances between the external parts of the analogs inside the plaster cast. The accuracy was also compared in five groups as follows; group 1: splinting of impression copings by auto-polymerizing acrylic resin, group 2: cutting the splinting of impres-sion copings with self-polymerizing acrylic resin, group 3: splinting of impression copings with a light-cured resin pattern (Jig-Gel), group 4: splinting of impression copings cut by a light-cured resin pattern, and group 5: impression with no splint. All statistical analyses were performed with SPSS 17. Statistical significance was set at P<0.05. Results. The highest impression accuracy was obtained in the group without cutting the splint of the impression copings using auto-polymerizing acrylic resin. Compared with the impression methods, impression making of non-splint samples in an impression coping was the least accurate, and the results for the two used methods were similar. Conclusion. The results of this study showed that the combination of the impression coping method and auto-polymerizing acrylic resin had the highest accuracy.

Comparison of the Effect of Inhalation Aromatherapy with 10% and 30% Peppermint Essential Oils on the Severity of Nausea in Abdominal Surgery Patients.

BACKGROUND: One of the most common surgical complications is nausea. Regarding the contradictory findings on the effect of aromatherapy with peppermint on the severity of nausea, in the present study, we aimed at comparing the effect of aromatherapy with 10% and 30% peppermint essential oils on the severity of nausea in surgical patients. METHODS: This single-blind randomized controlled trial was conducted at the surgical ward of Imam Reza Hospital in Kermanshah, Iran. A total of 120 patients undergoing abdominal surgery were randomly divided into three groups of 10% peppermint, 30% peppermint, and control (40 patients in each group) using a random number table. In each of the intervention groups, 0.2 ml of 10% and 30% peppermint essential oil was inhaled. In the control group, the same amount of distilled water colored with green food coloring was inhaled. The severity of nausea was measured by nausea visual analog scale (NVAS) before and 10 minutes after the intervention. RESULTS: In the 10% peppermint group, the mean severity of nausea before the intervention was 52.3 ± 13.7 out of 100, which reduced to 40.5 ± 13.5 after the intervention (p < 0.001). In the 30% peppermint group, the mean severity scores of nausea before and after the intervention were 60.2 ± 15.0 and 39.7 ± 12.4, respectively (p < 0.001). In the control group, the mean severity scores of nausea before and after the intervention was not statistically significant. There was no significant difference between the two intervention groups in terms of the mean severity of nausea after the intervention. CONCLUSIONS: It can be concluded that 10% and 30% peppermint essential oils are equally effective on the severity of nausea.

The effects of statins with a high hepatoselectivity rank on the extra-hepatic tissues; New functions for statins.

Statins, as the most common treatment for hyperlipidemia, exert effects beyond their lipid-lowering role which are known as pleiotropic effects. These effects are mainly due to the inhibition of isoprenoids synthesis and consequently blocking prenylation of proteins involved in the cellular signaling pathways regulating cell development, growth, and apoptosis. Statins target cholesterol synthesis in the liver as the major source of cholesterol in the body and so reduce whole-body cholesterol. The reduced level of cholesterol forces other organs to an adaptive homeostatic reaction to increase their cholesterol synthesis capacity, however, this only occurs when statins have unremarkable access to the extra-hepatic tissues. In order to reduce the adverse effects of statin on the skeletal muscle, most recent efforts have been towards formulating new statins with the highest level of hepatoselectivity rank and the least level of access to the extra-hepatic tissues; however, the inaccessibility of statins for the extra-hepatic tissues may induce several biological reactions. In this review, we aim to evaluate the effects of statins on the extra-hepatic tissues when statins have unremarkable access to these tissues.

Effects of statins on the chemoresistance-The antagonistic drug-drug interactions versus the anti-cancer effects.

There has been growing interest in the potential anti-cancer activity of statins based on evidence of their anti-proliferative, pro-apoptotic, and radiosensitizing properties, but no studies have focused on the effects of statins on the chemoresistance. In spite of their direct cytostatic/cytotoxic effects on the cancer cells, statins via drug interactions may affect therapeutic effects of the chemotherapy agents and so cause chemoresistance in cancer cells. Here, we aim to present the molecular mechanisms underlying cytotoxic effects of statins on the cancer cells against those mechanisms by which statins may lead to chemoresistance, in order to clarify whether the positive effects of the co-treatment of statins on the efficiency of chemotherapeutic agents is due to the natural anti-cancer effects of statins or it is due to increasing the cellular concentrations of chemotherapy drugs in cancer cells.

Effects of Rosuvastatin on the expression of the genes involved in cholesterol metabolism in rats: adaptive responses by extrahepatic tissues.

BACKGROUND: Statins mostly target the liver; therefore, increase in the synthesis of cholesterol by extra-hepatic tissues and then transferring this cholesterol to the liver can be regarded as adaptive responses by these tissues. In addition to cholesterol, these adaptive responses can increase isoprenoid units as the byproducts of the cholesterol biosynthesis pathway; isoprenoids play a key role in regulating cell signaling pathways and cancer development. Thus, there is a primary need for in vivo investigation of the effects of statins on the cholesterol metabolism in the extra-hepatic tissues. MATERIALS: Eighteen male Sprague-Dawley rats were randomly divided into control (n = 9) and treatment (n = 9) groups. The treatment group was orally given 10 mg/kg/day of Rosuvastatin for 6 weeks. Then, serum lipid profile, expression levels of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR), ABCA1, ABCG1 and ApoA1, and activity of HMGCR were measured in the liver, intestine and adipose tissues. RESULTS: Rosuvastatin significantly reduced total cholesterol and LDL-C. The expression levels of ABCA1, ABCG1, and ApoA1 in the liver and HMGCR in both liver and intestine were significantly increased in the Rosuvastatin treated-group. However, in the intestine, there were no significant differences in the expression levels of ABCA1 and ABCG1 between the study groups. Rosuvastatin had no effect on the adipose tissue. The HMGCR activity was significantly increased in the liver and intestine of the Rosuvastatin-treated group. CONCLUSIONS: In spite of the adipose tissue, the intestine efficiently responses to the reduced levels of cholesterol and increases its cholesterogenesis capacity. However, adipose tissue seems to play a small role in correcting cholesterol deficiency during the course of statin therapy.

Oxidative stress as a possible mechanism of statin-induced myopathy.

Statins, inhibitors of hydroxy methyl glutaryl coenzyme-A (HMG-CoA) reductase, are the most widely used drugs for treating hypercholesterolemia. However, statins can cause disabling myopathy as their main adverse effect. Several molecular mechanisms underlie the statin-induced myopathy including the decrease in the levels of essential mevalonate and cholesterol derivatives. This review discusses a further mechanism involving the loss of other anti-oxidant defenses besides ubiquinone (Co-Q) in skeletal muscles which produce a significant amount of reactive oxygen species (ROS). Therefore, to maintain their function, skeletal muscles need a high level of anti-oxidants.

Suppression of p53R2 gene expression with specific siRNA sensitizes HepG2 cells to doxorubicin.

INTRODUCTION: p53R2 is a p53-inducible protein that contributes to DNA repair by providing dNTPs in response to DNA damage. The roles of p53R2 in cancer cells and malignancies still remain controversial. Herein, we examined the effects of p53R2 silencing on HepG2 human hepatocellular carcinoma (HHC) cell line (wild-type p53) viability, apoptosis and cell cycle arrest in the presence and absence of doxorubicin. METHODS: Cell transfection was performed using a liposomal approach. Gene silencing was determined by quantitative real-time PCR and western blot analysis. To evaluate the cell growth rate after transfection, trypan blue dye exclusion assay was employed. The cytotoxicity of the doxorubicin and p53R2 siRNA as single agents or in combination against HepG2 cell was analyzed by MTT assay and the drug combination effects was evaluated by calculating the combination index. The effects of treatments on different stages of cell cycle were analyzed by flow cytometry using propidium iodide (PI) and induction of apoptosis was assessed using DNA-histone ELISA. RESULTS: We found that silencing of p53R2 alone had a strong effect on growth inhibition and spontaneous apoptosis in HepG2 cells. p53R2 siRNA synergistically enhanced the cytotoxic effect of doxorubicin. Furthermore, when used in combination with doxorubicin (0.4µM), a significant increase in the rate of apoptosis was observed (P<0.05). Moreover, cell cycle at S and G2/M phases progressed at a lower rate after p53R2 combination treatment compared with doxorubicin mono-therapy. CONCLUSION: These findings suggest that siRNA-mediated silencing of p53R2 has great potential as a therapeutic tool and adjuvant in chemotherapy.

Curcumin as a potential candidate for treating hyperlipidemia: A review of cellular and metabolic mechanisms.

Curcumin is an herbal polyphenol extensively investigated for antioxidant, anti-inflammatory, and hypolipidaemic properties. In the present review, the efficacy of curcumin for improving a plasma lipid profile has been evaluated and compared with statins, a well-known class of medicines for treating hypercholesterolemia and hyperlipidaemia. Curcumin is presumably most effective in reducing triglyceride (TG), while statins are most efficient in lowering low-density lipoproteins-cholesterol (LDL-C). Additionally, various molecular and metabolic mediators of cholesterol and plasma lipid homeostasis are discussed in relation to how they are modulated by curcumin or statins. Overall, curcumin influences the same mediators of plasma lipid alteration as statins do. Almost all the pathways through which cholesterol trafficking takes place are affected by these agents. These include gastrointestinal absorption of dietary cholesterol, hepatocellular removal of plasma cholesterol, the mediators of reverse cholesterol transport, and removal of cholesterol from peripheral tissues. Moreover, the reactive oxygen species (ROS) scavenging potential of curcumin limits the risk of lipid peroxidation that triggers inflammatory responses causing cardiovascular diseases (CVD) and atherosclerosis. Taken together, curcumin could be used as a safe and well-tolerated adjunct to statins to control hyperlipidaemia more effectively than statins alone.

The effect of statins on the organs: similar or contradictory?

Hydroxy-Methyl-Glutaryl-CoA reductase (HMGCR) - the main enzyme of the cholesterol biosynthesis pathway - is mostly inhibited by statins in hepatocytes. In spite of the other tissues, liver utilizes cholesterol in different ways such as the synthesis of bile acids, excretion in to the intestine and synthesis of lipoproteins. Therefore, statins theoretically alter these pathways; although, there have not been such effects. In this review, we aim to show the roles of extra-hepatic tissues, in particular intestine, adipose and cutaneous tissues in providing the cholesterol after reduction of the whole body cholesterol content by statins.

The balance between induction and inhibition of mevalonate pathway regulates cancer suppression by statins: A review of molecular mechanisms.

Statins are widely used drugs for their role in decreasing cholesterol in hypercholesterolemic patients. Statins through inhibition of Hydroxy Methyl Glutaryl-CoA Reductase (HMGCR), the main enzyme of the cholesterol biosynthesis pathway, inhibit mevalonate pathway that provides isoprenoids for prenylation of different proteins such as Ras superfamily which has an essential role in cancer developing. Inhibition of the mevalonate/isoprenoid pathway is the cause of the cholesterol independent effects of statins or pleotropic effects. Depending on their penetrance into the extra-hepatic cells, statins have different effects on mevalonate/isoprenoid pathway. Lipophilic statins diffuse into all cells and hydrophilic ones use a variety of membrane transporters to gain access to cells other than hepatocytes. It has been suggested that the lower accessibility of statins for extra-hepatic tissues may result in the compensatory induction of mevalonate/isoprenoid pathway and so cancer developing. However, most of the population-based studies have demonstrated that statins have no effect on cancer developing, even decrease the risk of different types of cancer. In this review we focus on the cancer developing "potentials" and the anti-cancer "activities" of statins regarding the effects of statins on mevalonate/isoprenoid pathway in the liver and extra-hepatic tissues.

Multiple functions of p21 in cell cycle, apoptosis and transcriptional regulation after DNA damage.

An appropriate control over cell cycle progression depends on many factors. Cyclin-dependent kinase (CDK) inhibitor p21 (also known as p21(WAF1/Cip1)) is one of these factors that promote cell cycle arrest in response to a variety of stimuli. The inhibitory effect of P21 on cell cycle progression correlates with its nuclear localization. P21 can be induced by both p53-dependent and p53-independent mechanisms. Some other important functions attributed to p21 include transcriptional regulation, modulation or inhibition of apoptosis. These functions are largely dependent on direct p21/protein interactions and also on p21 subcellular localizations. In addition, p21 can play a role in DNA repair by interacting with proliferating cell nuclear antigen (PCNA). In this review, we will focus on the multiple functions of p21 in cell cycle regulation, apoptosis and gene transcription after DNA damage and briefly discuss the pathways and factors that have critical roles in p21 expression and activity.

Clofarabine Has Apoptotic Effect on T47D Breast Cancer Cell Line via P53R2 Gene Expression.

PURPOSE: Clofarabine, a purine nucleoside analogue and inhibitor of Ribonucleotide Reductase (RR), is used for treatment of leukemia. Clofarabine-induced defect in DNA replication, induces p53 and subsequently P53R2 genes as subunit of RR. clofarabine deregulated P53R2 gene expression leading to the elevated levels of P53R2 which impose resistance to DNA damaging drugs. In this study the apoptotic and cytotoxic effects of clofarabine has been investigated on breast cancer cell line. METHODS: Cofarabine cytotoxicity on T47D cells has been studied by MTT assay. T47D cells were exposed to the different concentrations of clofarabine for 24, 48 and 72 hours intervals. Relative expression of P53R2 gene has been studied using real-time PCR. Moreover, after treating with clofarabine the apoptotic and necrotic cells were detected using Annexin V and propodium iodide (PI) reagents by flowcytometry technique. RESULTS: MTT assay results showed that the clofarabine IC50 on T47D cell line were 3 and 2.5µM after 48 and 72 h exposure, respectively. Clofarabine did not show any significant cytotoxic effect after 24 h exposure. The analysis of qRT-PCR showed a significant increase in P53R2 gene expression in treated cells with both 2.5 and 3 µM doses and also, the results of flowcytometry revealed 26.91 and 74.46 percent apoptosis induction in 48 and 72h treatments respectively in comparison to the control groups. CONCLUSION: Our results showed that apoptotic and cytotoxic effects of clofarabine on T47D cell line were in time and dose dependent manner; therefore it could be considered a new candidate in breast cancer therapy.

Akt and p53R2, partners that dictate the progression and invasiveness of cancer.

The serine/threonine kinase or the so-called "Akt" is a key regulatory molecule of signaling pathway that regulates various cellular processes. Many intracellular proteins are involved in the activation or inhibition of Akt signaling and the hyperactivation of Akt signaling pathway is found to be frequently involved in various types of human cancers. Furthermore, while p53R2, a p53-inducible peptide involved in the synthesis of dNTPs normally works toward suppression of cancer through elimination of reactive oxygen species (ROS), inhibition of MAPK/ERK pathway and providing dNTPs for DNA repair, the overexpression of p53R2 is reported to be associated with cancer progression and resistance to therapy. In this review article, we will discuss the situation in which cancer cells with hyperactive PI3K/Akt signaling can recruit p53R2 in favor of cancer progression and resistance to therapy. In the hyperactive state of PI3K/Akt signaling (which happens in the absence of deactivation or excess of activation), p53R2 can be used by cancer cells to promote proliferation. Therefore, the hyperactivity of PI3K/Akt pathway and elevated levels of p53R2 can give rise to highly invasive cancers.

Serum arsenic and lipid peroxidation levels in patients with multiple sclerosis.

Oxidative stress plays a crucial role in the pathogenesis of multiple sclerosis (MS). Previous studies have shown that oxidative stress is one of the main underlying mechanisms of arsenic-induced cellular damage. The aim of this study was to assess the serum levels of arsenic and its relationship with lipid peroxidation in MS patients from Tabriz, as the third polluted city of Iran. The study population included 38 MS female patients and 38 age-matched healthy controls. Serum malondialdehyde (MDA) and arsenic levels were measured using thiobarbituric acid reactive substances (TBARS) assay and electrothermal atomic absorption spectrometry, respectively. The results showed that the arsenic (P < 0.01) and MDA (P = 0.03) levels were significantly higher in patients with MS than those in control. Moreover, serum levels of arsenic and MDA were positively correlated in MS patients. The elevated levels of serum arsenic might explain the increased oxidative stress in MS patients. We suggest that high arsenic levels in serum may lead to MS development, and therefore, exposure to this metal should be limited.