MicroRNA-Mediated Drug Repurposing Unveiled Potential Candidate Drugs for Prolactinoma Treatment.

INTRODUCTION: Prolactinomas, also called lactotroph adenomas, are the most encountered type of hormone-secreting pituitary neuroendocrine tumors in the clinic. The preferred first-line therapy is a medical treatment with dopamine agonists (DAs), mainly cabergoline, to reduce serum prolactin levels, tumor volume, and mass effect. However, in some cases, patients have displayed DA resistance with aggressive tumor behavior or are faced with recurrence after drug withdrawal. Also, currently used therapeutics have notorious side effects and impair the life quality of the patients. METHODS: Since the amalgamation of clinical and laboratory data besides tumor histopathogenesis and transcriptional regulatory features of the tumor emerges to exhibit essential roles in the behavior and progression of prolactinomas; in this work, we integrated mRNA- and microRNA (miRNA)-level transcriptome data that exploit disease-specific signatures in addition to biological and pharmacological data to elucidate a rational prioritization of pathways and drugs in prolactinoma. RESULTS: We identified 8 drug candidates through drug repurposing based on mRNA-miRNA-level data integration and evaluated their potential through in vitro assays in the MMQ cell line. Seven repurposed drugs including 5-fluorocytosine, nortriptyline, neratinib, puromycin, taxifolin, vorinostat, and zileuton were proposed as potential drug candidates for the treatment of prolactinoma. We further hypothesized possible mechanisms of drug action on MMQ cell viability through analyzing the PI3K/Akt signaling pathway and cell cycle arrest via flow cytometry and Western blotting. DISCUSSION: We presented the transcriptomic landscape of prolactinoma through miRNA and mRNA-level data integration and proposed repurposed drug candidates based on this integration. We validated our findings through testing cell viability, cell cycle phases, and PI3K/Akt protein expressions. Effects of the drugs on cell cycle phases and inhibition of the PI3K/Akt pathway by all drugs gave us promising output for further studies using these drugs in the treatment of prolactinoma. This is the first study that reports miRNA-mediated repurposed drugs for prolactinoma treatment via in vitro experiments.

The Repertoire of Glycan Alterations and Glycoproteins in Human Cancers.

Cancer as the leading cause of death worldwide has many issues that still need to be addressed. Since the alterations on the glycan compositions or/and structures (i.e., glycosylation, sialylation, and fucosylation) are common features of tumorigenesis, glycomics becomes an emerging field examining the structure and function of glycans. In the past, cancer studies heavily relied on genomics and transcriptomics with relatively little exploration of the glycan alterations and glycoprotein biomarkers among individuals and populations. Since glycosylation of proteins increases their structural complexity by several orders of magnitude, glycome studies resulted in highly dynamic biomarkers that can be evaluated for cancer diagnosis, prognosis, and therapy. Glycome not only integrates our genetic background with past and present environmental factors but also offers a promise of more efficient patient stratification compared with genetic variations. Therefore, studying glycans holds great potential for better diagnostic markers as well as developing more efficient treatment strategies in human cancers. While recent developments in glycomics and associated technologies now offer new possibilities to achieve a high-throughput profiling of glycan diversity, we aim to give an overview of the current status of glycan research and the potential applications of the glycans in the scope of the personalized medicine strategies for cancer.

The potential use of natural products to negate hepatic, renal and neuronal toxicity induced by cancer therapeutics.

Different types of chemotherapeutics are used for cancer treatment. These drugs act on several signal pathways, lead to programmed cell death, and damage cancer cells. Although many specific mechanisms of action have been suggested for chemotherapeutics, there are still gaps in understanding their effects. They may affect different components of the cell, particularly proteins with specific functions, such as enzymes. Recently, targeted and immuno therapies were introduced for treatment of different cancers. However, many cancer patients still depend on traditional and well-known drugs. Doxorubicin and platinum-based drugs are among the most frequently used chemotherapeutics. They are highly cytotoxic for cancer cells, but they also act on healthy cells. Hence, it is crucial to understand the mechanisms involved in order to decrease their side effects. Natural products, many of which are also available over-the-counter, may be considered to decrease various cancer drug-induced side effects. This review focuses on the use of these compounds to overcome side effects of chemotherapeutics, primarily doxorubicin and cisplatin, in the liver, kidney, and neuronal systems.

Indocyanine green based fluorescent polymeric nanoprobes for in vitro imaging.

Indocyanine green (ICG) provides an advantage in the imaging of deep tumors as it can reach deeper location without being absorbed in the upper layers of biological tissues in the wavelengths, which named "therapeutic window" in the tissue engineering. Unfortunately, rapid elimination and short-term stability in aqueous media limited its use as a fluorescence probe for the early detection of cancerous tissue. In this study, stabilization of ICG was performed by encapsulating ICG molecules into the biodegradable polymer composited with poly(l-lactic acid) and poly(ε-caprolactone) via a simple one-step multiaxial electrospinning method. Different types of coaxial and triaxial structure groups were performed and compared with single polymer only groups. Confocal microscopy was used to image the encapsulated ICG (1 mg/mL) within electrospun nanofibers and in vitro ICG uptake by MIA PaCa-2 pancreatic cancer cells. Stability of encapsulated ICG is demonstrated by the in vitro sustainable release profile in PBS (pH = 4 and 7) up to 21 days. These results suggest the potential of the ability of internalization and accommodation of ICG into the pancreatic cell cytoplasm from in vitro implanted ICG-encapsulated multiaxial nanofiber mats. ICG-encapsulated multilayer nanofibers may be promising for the local sustained delivery system to eliminate loss of dosage caused by direct injection of ICG-loaded nanoparticles in systemic administration.

Intraluminal fluid infusion in a rat jejunum ischemia/reperfusion model is associated with improved tissue perfusion and less mucosal damage.

OBJECTIVE: This study used an experimental model mimicking early postoperative enteral feeding after the transfer of free jejunal flap and tested the hypothesis that jejunal infusion with dextrose or saline is associated with improved tissue perfusion and/or less mucosal damage after ischemia/reperfusion (IR) injury. METHODS: Thirty-five male Sprague Dawley rats were randomly divided into five groups: sham group (no IR and no intraluminal infusion); IR control group (IR but not intraluminal infusion); IR plus intraluminal 0.9% NaCl infusion or 5% dextrose or 10% dextrose infusion groups. A jejunal segment of each rat was isolated. The animals had jejunal ischemia for 40 min, reperfusion, and intestinal infusion on the basis of their allocation. Jejunal tissue perfusion was measured with laser Doppler flowmetry at one hour and two hours after reperfusion, after which the animals were sacrificed and tissue samples were obtained for the scoring of histological damage at superficial and cryptic epithelium, villus structure, and inflammatory cell infiltration and tissue nitric oxide (NO), interleukin (IL)-1, IL-6, and matrix metalloproteinase-1 (MMP) level measurements. RESULTS: At 1 h of reperfusion, IR plus 5% dextrose and 10% dextrose groups both had significantly higher perfusion rates than the IR control group (384.8 ± 26.7 and 462.4 ± 44.7 versus 270.3 ± 34.2 PU, respectively, p < 0.05 for both). These differences were maintained at 2 h of reperfusion (p < 0.05 for both). Saline infusion, however, resulted in improved tissue perfusion only at the early phase of reperfusion. Intraluminal infusion with dextrose solution, either 5% or 10%, was associated with higher tissue NO, IL-1, and IL-6 levels than that in the sham group (p < 0.05 for all). In addition, intraluminal infusion of any fluid resulted in less severe histological damage (8.1 ± 0.9 versus 5.8 ± 1.0, 5.4 ± 0.9, and 5.2 ± 1.9, for IR plus saline, 5% dextrose and 10% dextrose groups, respectively, p < 0.05 for all). CONCLUSIONS: Intraluminal infusion of fluids, particularly dextrose solutions, may be protective against IR injury as demonstrated by improved tissue perfusion and less histological damage. In addition, increases in tissue NO, IL-1, and IL-6 levels in association with dextrose infusion may be explained by the activation of pro-inflammatory and anti-inflammatory protective pathways. These support early enteral feeding after free jejunum flap transfers; however, further studies are warranted.

PPP2R3C gene variants cause syndromic 46,XY gonadal dysgenesis and impaired spermatogenesis in humans.

Context Most of the knowledge on the factors involved in human sexual development stems from studies of rare cases with disorders of sex development. Here, we have described a novel 46, XY complete gonadal dysgenesis syndrome caused by homozygous variants in PPP2R3C gene. This gene encodes B″gamma regulatory subunit of the protein phosphatase 2A (PP2A), which is a serine/threonine phosphatase involved in the phospho-regulation processes of most mammalian cell types. PPP2R3C gene is most abundantly expressed in testis in humans, while its function was hitherto unknown. Patients and methods Four girls from four unrelated families with 46, XY complete gonadal dysgenesis were studied using exome or Sanger sequencing of PPP2R3C gene. In total, four patients and their heterozygous parents were investigated for clinical, laboratory, immunohistochemical and molecular characteristics. Results We have identified three different homozygous PPP2R3C variants, c.308T>C (p.L103P), c.578T>C (p.L193S) and c.1049T>C (p.F350S), in four girls with 46, XY complete gonadal dysgenesis. Patients also manifested a unique syndrome of extragonadal anomalies, including typical facial gestalt, low birth weight, myopathy, rod and cone dystrophy, anal atresia, omphalocele, sensorineural hearing loss, dry and scaly skin, skeletal abnormalities, renal agenesis and neuromotor delay. We have shown a decreased SOX9-Phospho protein expression in the dysgenetic gonads of the patients with homozygous PPP2R3C variants suggesting impaired SOX9 signaling in the pathogenesis of gonadal dysgenesis. Heterozygous males presented with abnormal sperm morphology and impaired fertility. Conclusion Our findings suggest that PPP2R3C protein is involved in the ontogeny of multiple organs, especially critical for testis development and spermatogenesis. PPPR3C provides insight into pathophysiology, as well as emerging as a potential therapeutic target for male infertility.

Proteomic approach for understanding milder neurotoxicity of Carfilzomib against Bortezomib.

The proteasomal system is responsible for the turnover of damaged proteins. Because of its important functions in oncogenesis, inhibiting the proteasomal system is a promising therapeutic approach for cancer treatment. Bortezomib (BTZ) is the first proteasome inhibitor approved by FDA for clinical applications. However neuropathic side effects are dose limiting for BTZ as many other chemotherapeutic agents. Therefore second-generation proteasome inhibitors have been developed including carfilzomib (CFZ). Aim of the present work was investigating the mechanisms of peripheral neuropathy triggered by the proteasome inhibitor BTZ and comparing the pathways affected by BTZ and CFZ, respectively. Neural stem cells, isolated from the cortex of E14 mouse embryos, were treated with BTZ and CFZ and mass spectrometry was used to compare the global protein pool of treated cells. BTZ was shown to cause more severe cytoskeletal damage, which is crucial in neural cell integrity. Excessive protein carbonylation and actin filament destabilization were also detected following BTZ treatment that was lower following CFZ treatment. Our data on cytoskeletal proteins, chaperone system, and protein oxidation may explain the milder neurotoxic effects of CFZ in clinical applications.

CD36 expression in peripheral blood mononuclear cells reflects the onset of atherosclerosis.

Together with complex genetic and environmental factors, increased serum cholesterol and ox-LDL levels are considered as major triggering factors of atherosclerosis. Mononuclear cell infiltration to the arterial wall and uptake of ox-LDL, which is facilitated by CD36 receptor through an uncontrolled manner, play a key role in foam cell formation followed by atherogenesis development. The aim of this study was to analyze if CD36 expression in peripheral blood mononuclear cells reflect its aortic tissue level in hypercholesterolemia. In this study, CD36 protein expression was evaluated in aortic specimens of cholesterol or cholesterol plus Vitamin E treated animals in relation to the immunohistochemical analyses for the HNE-protein adducts, as well as for smooth muscle actin and vimentin. The CD36 mRNA expression was determined by RT-PCR in PBMC of hypercholesterolemic rabbits and hypercholesterolemic versus normocholesterolemic individuals. Immunohistochemistry findings revealed that smooth muscle actin, smooth muscle vimentin, HNE-protein conjugates, and CD36 protein expressions were significantly increased in aorta of hypercholesterolemic group where foam cells were present. High cholesterol diet significantly induced CD36 mRNA expression in both rabbit aorta and PBMCs, while positive correlation between aortic and PBMC CD36 expression has been found. In addition, consistent with the rabbit model, CD36 mRNA expression levels in human PBMCs were significantly higher in hypercholesterolemic patients than in normocholesterolemic individuals. Taken together, these results demonstrate that the CD36 mRNA levels of PBMCs could reflect the CD36 mRNA levels in aorta and could be used as a biomarker for diagnosis of atherosclerotic burden. © 2018 BioFactors, 44(6):588-596, 2018.

Proteasome Inhibitors in Cancer Therapy and their Relation to Redox Regulation.

Redox homeostasis is important for the maintenance of cell survival. Under physiological conditions, redox system works in a balance and involves activation of many signaling molecules. Regulation of redox balance via signaling molecules is achieved by different pathways and proteasomal system is a key pathway in this process. Importance of proteasomal system on signaling pathways has been investigated for many years. In this direction, many proteasome targeting molecules have been developed. Some of them are already in the clinic for cancer treatment and some are still under investigation to highlight underlying mechanisms. Although there are many studies done, molecular mechanisms of proteasome inhibitors and related signaling pathways need more detailed explanations. This review aims to discuss redox status and proteasomal system related signaling pathways. In addition, cancer therapies targeting proteasomal system and their effects on redox-related pathways have been summarized.

Protective effects of different exercise modalities in an Alzheimer's disease-like model.

Our aim was to investigate the probable protective effects of aerobic, resistance and combined exercise methods on ovariectomy and d-galactose induced Alzheimer's Disease (AD)-like model. d-galactose (100mg/kg) or saline were administered intraperitoneally for 6 weeks to ovariectomized or sham-operated rats (n=8/group). Aerobic (AE), resistance (RE) and combined exercises (CE) (aerobic+resistance) were performed for 3 times a week for 6 weeks. Anxiety level and cognitive functions were evaluated via hole-board and object recognition tests. Brain myeloperoxidase, malondialdehyde, nitric oxide activity, lucigenin-enhanced chemiluminescence, glutathione and serum insulin like growth factor-I (IGF-I) assays were done. Hippocampal mRNA levels of nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), and amyloid precursor protein 695 (APP695) were measured. Amyloid Beta (Aß), NGF, BDNF, IGF-I immunoreactive neurons were evaluated. Freezing time were increased in AD-like model and decreased back with AE (p<0.05). Deteriorated working memory in AD-like model was improved with all exercise types (p<0.05-0.001). Reduced glutathione levels in AD-like model were increased and increased malondialdehyde levels were reduced and serum IGF-I levels were increased by all exercises (p<0.05-0.001). Increased APP mRNA levels in AD-like model were decreased via CE (p<0.05). Elevated Aß scores in AD-like model were decreased by RE and CE (p<0.01) in hippocampus and by all exercise types in cortex (p<0.05-0.01). Decreased cortical NGF immunocytochemical scores of AD-like model were increased by CE (p<0.05). Different exercise models may have protective effects in development stage of AD via reducing oxidative stress and Aß scores, and by improving antioxidant system and brain plasticity.

Repair of critical size defects using bioactive glass seeded with adipose-derived mesenchymal stem cells.

Bioactive glass has been demonstrated as a biocompatible bone substitute. However bone healing process can be prolonged due to late resorption of the material. Adipose derived stem cells (ASC) have osteogenic differentiation potential and hence can be a cell source for bone regeneration. The aim of this study was to test whether combination of bioactive glass with ASCs would enhance bone regeneration. Following creation of critical sized defects on the calvaria of 32 Wistar rats, the animals were randomly divided into four groups: Group C (control): Defects were left untreated; Group G: Defects were covered with autologous bone graft; Group BG: Defects were filled with bioactive glass; Group BG/ASC: Defects were filled with bioactive glass seeded with ASCs. The defect size was significantly greater in Group C compared to all other groups. Bone density was significantly lower in Group C compared to Group G and Group BG/ASC. Bone regeneration score of Group C was significantly lower than other groups. Group BG/ASC demonstrated lamellar bone and havers canal formation. The results of this study demonstrated that bioactive glass implanted with ASC is a biocompatible construct stimulating radiologically and histologically evident bone regeneration similar to autologous bone grafting. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1002-1008, 2017.

Proteasome inhibitors in cancer therapy: Treatment regimen and peripheral neuropathy as a side effect.

Proteasomal system plays an important role in protein turnover, which is essential for homeostasis of cells. Besides degradation of oxidized proteins, it is involved in the regulation of many different signaling pathways. These pathways include mainly cell differentiation, proliferation, apoptosis, transcriptional activation and angiogenesis. Thus, proteasomal system is a crucial target for treatment of several diseases including neurodegenerative diseases, cystic fibrosis, atherosclerosis, autoimmune diseases, diabetes and cancer. Over the last fifteen years, proteasome inhibitors have been tested to highlight their mechanisms of action and used in the clinic to treat different types of cancer. Proteasome inhibitors are mainly used in combinational therapy along with classical chemo-radiotherapy. Several studies have proved their significant effects but serious side effects such as peripheral neuropathy, limits their use in required effective doses. Recent studies focus on peripheral neuropathy as the primary side effect of proteasome inhibitors. Therefore, it is important to delineate the underlying mechanisms of peripheral neuropathy and develop new inhibitors according to obtained data. This review will detail the role of proteasome inhibition in cancer therapy and development of peripheral neuropathy as a side effect. Additionally, new approaches to prevent treatment-limiting side effects will be discussed in order to help researchers in developing effective strategies to overcome side effects of proteasome inhibitors.

Endoplasmic reticulum stress related molecular mechanisms in nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) is considered to be a common health problem since the incidence of nonalcoholic fatty liver disease (NAFLD) has increased in recent years. Disturbed hepatic cholesterol homeostasis and free cholesterol accumulation in liver results in increased oxidative stress leading to the endoplasmic reticulum (ER) stress. Activated ER stress maintains protein homeostasis however, delayed or inadequate ER stress responses may induce fat accumulation, insulin resistance, inflammation, apoptosis, and autophagy, all of which increase with age and play crucial roles in the pathogenesis of NASH. In aging research, there is a growing interest for the role of ER stress in the progression of NASH since aging seems to favor NAFLD according to its pathogenesis. On the other hand, specific microRNAs (miRNAs) expression profiles are strongly related with ER stress as well as NASH progresses. This review highlights molecular mechanisms related to ER stress in the pathogenesis of NASH and miRNAs for the progression and treatment of the disease.

Quercetin-Induced Cell Death in Human Papillary Thyroid Cancer (B-CPAP) Cells.

In this study, we have investigated the antiproliferative effect of quercetin on human papillary thyroid cancer cells and determined the apoptotic mechanisms underlying its actions. We have used different concentrations of quercetin to induce apoptosis and measured cell viability. Apoptosis and cell cycle analysis was determined by flow cytometry using Annexin V and propidium iodide. Finally, we have measured changes in caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP) protein expression levels as hallmarks of apoptosis and Hsp90 protein expression level as a marker of proteasome activity in treated and control cells. Quercetin treatment of human papillary thyroid cancer cells resulted in decreased cell proliferation and increased rate of apoptosis by caspase activation. Furthermore, it was demonstrated that quercetin induces cancer cell apoptosis by downregulating the levels of Hsp90. In conclusion, we have shown that quercetin induces downregulation of Hsp90 expression that may be involved in the decrease of chymotrypsin-like proteasome activity which, in order, induces inhibition of growth and causes cell death in thyroid cancer cells. Thus, quercetin appears to be a promising candidate drug for Hsp90 downregulation and apoptosis of thyroid cancer cells.

Nrf2 silencing to inhibit proteolytic defense induced by hyperthermia in HT22 cells.

Nrf2 pathway has been known to be protective against cancer progression however recent studies have revealed that the antioxidant activity of Nrf2 contributes to chemotherapy resistance. For many years, hyperthermia has been used as an additional therapy to increase the efficiency of chemotherapy and radiotherapy. Besides the positive effects of hyperthermia during treatment procedure, thermotolerance has been found to develop against heat treatment. Although the involved molecular mechanisms have not been fully clarified, heat shock proteins (HSP) and proteasome activity are known to be involved in the acquisition of thermotolerance. The aim of this study was to investigate the potential beneficial effects of combining hyperthermia with Nrf2 silencing to inhibit molecular mechanisms leading to induction of defense mechanisms in transcription level. Following heat treatment of HT22 cells, HSP70 and the proteasome levels and as well as proteasome activity were found to be elevated in the nucleus. Our results demonstrated that Nrf2 silencing reduced defense mechanisms against heat treatment both in antioxidant and proteolytic manner and Nrf2 may be a potential target for therapeutic approach in order to improve the beneficial effects of hyperthermia in cancer therapy.

Endoplasmic reticulum stress and proteasomal system in amyotrophic lateral sclerosis.

Protein processing including folding, unfolding and degradation is involved in the mechanisms of many diseases. Unfolded protein response and/or endoplasmic reticulum stress are accepted to be the first steps which should be completed via protein degradation. In this direction, proteasomal system and autophagy play important role as the degradation pathways and controlled via complex mechanisms. Amyotrophic lateral sclerosis is a multifactorial neurodegenerative disease which is also known as the most catastrophic one. Mutation of many different genes are involved in the pathogenesis such as superoxide dismutase 1, chromosome 9 open reading frame 72 and ubiquilin 2. These genes are mainly related to the antioxidant defense systems, endoplasmic reticulum stress related proteins and also protein aggregation, degradation pathways and therefore mutation of these genes cause related disorders.This review focused on the role of protein processing via endoplasmic reticulum and proteasomal system in amyotrophic lateral sclerosis which are the main players in the pathology. In this direction, dysfunction of endoplasmic reticulum associated degradation and related cell death mechanisms that are autophagy/apoptosis have been detailed.

Basic mechanisms in endoplasmic reticulum stress and relation to cardiovascular diseases.

The folding process is an important step in protein synthesis for the functional shape or conformation of the protein. The endoplasmic reticulum (ER) is the main organelle for the correct folding procedure, which maintains the homeostasis of the organism. This process is normally well organized under unstressed conditions, whereas it may fail under oxidative and ER stress. The unfolded protein response (UPR) is a defense mechanism that removes the unfolded/misfolded proteins to prevent their accumulation, and two main degradation systems are involved in this defense, including the proteasome and autophagy. Cells decide which mechanism to use according to the type, severity, and duration of the stress. If the stress is too severe and in excess, the capacity of these degradation mechanisms, proteasomal degradation and autophagy, is not sufficient and the cell switches to apoptotic death. Because the accumulation of the improperly folded proteins leads to several diseases, it is important for the body to maintain this balance. Cardiovascular diseases are one of the important disorders related to failure of the UPR. Especially, protection mechanisms and the transition to apoptotic pathways have crucial roles in cardiac failure and should be highlighted in detailed studies to understand the mechanisms involved. This review is focused on the involvement of the proteasome, autophagy, and apoptosis in the UPR and the roles of these pathways in cardiovascular diseases.

Regulation of protein turnover by heat shock proteins.

Protein turnover reflects the balance between synthesis and degradation of proteins, and it is a crucial process for the maintenance of the cellular protein pool. The folding of proteins, refolding of misfolded proteins, and also degradation of misfolded and damaged proteins are involved in the protein quality control (PQC) system. Correct protein folding and degradation are controlled by many different factors, one of the most important of which is the heat shock protein family. Heat shock proteins (HSPs) are in the class of molecular chaperones, which may prevent the inappropriate interaction of proteins and induce correct folding. On the other hand, these proteins play significant roles in the degradation pathways, including endoplasmic reticulum-associated degradation (ERAD), the ubiquitin-proteasome system, and autophagy. This review focuses on the emerging role of HSPs in the regulation of protein turnover; the effects of HSPs on the degradation machineries ERAD, autophagy, and proteasome; as well as the role of posttranslational modifications in the PQC system.

Potential role of proteasome on c-jun related signaling in hypercholesterolemia induced atherosclerosis.

Atherosclerosis and its complications are major causes of death all over the world. One of the major risks of atherosclerosis is hypercholesterolemia. During atherosclerosis, oxidized low density lipoprotein (oxLDL) regulates CD36-mediated activation of c-jun amino terminal kinase-1 (JNK1) and modulates matrix metalloproteinase (MMP) induction which stimulates inflammation with an invasion of monocytes. Additionally, inhibition of proteasome leads to an accumulation of c-jun and phosphorylated c-jun and activation of activator protein-1 (AP-1) related increase of MMP expression. We have previously reported a significant increase in cluster of differentiation 36 (CD36) mRNA levels in hypercholesterolemic rabbits and shown that vitamin E treatment prevented the cholesterol induced increase in CD36 mRNA expression. In the present study, our aim is to identify the signaling molecules/transcription factors involved in the progression of atherosclerosis following CD36 activation in an in vivo model of hypercholesterolemic (induced by 2% cholesterol containing diet) rabbits. In this direction, proteasomal activities by fluorometry and c-jun, phospo c-jun, JNK1, MMP-9 expressions by quantitative RT-PCR and immunoblotting were tested in aortic tissues. The effects of vitamin E on these changes were also investigated in this model. As a result, c-jun was phosphorylated following decreased proteasomal degradation in hypercholesterolemic group. MMP-9 expression was also increased in cholesterol group rabbits contributing to the development of atherosclerosis. In addition, vitamin E showed its effect by decreasing MMP-9 levels and phosphorylation of c-jun.