Melittin, a major bioactive component of bee venom toxin, inhibits PDGF receptor beta-tyrosine phosphorylation and downstream intracellular signal transduction in rat aortic vascular smooth muscle cells

Immunomodulatory activities and biomedical applications of melittin and its recent advances

Melittin (MLT), a peptide containing 26 amino acids, is a key constituent of bee venom. It comprises ∼40%-60% of the venom's dry weight and is the main pricing index for bee venom, being the causative factor of pain. The unique properties of MLT extracted from bee venom have made it a very valuable active ingredient in the pharmaceutical industry as this cationic and amphipathic peptide has propitious effects on human health in diverse biological processes. It has the ability to strongly impact the membranes of cells and display hemolytic activity with anticancer characteristics. However, the clinical application of MLT has been limited by its severe hemolytic activity, which poses a challenge for therapeutic use. By employing more efficient mechanisms, such as modifying the MLT sequence, genetic engineering, and nano-delivery systems, it is anticipated that the limitations posed by MLT can be overcome, thereby enabling its wider application in therapeutic contexts. This review has outlined recent advancements in MLT's nano-delivery systems and genetically engineered cells expressing MLT and provided an overview of where the MLTMLT's platforms are and where they will go in the future with the challenges ahead. The focus is on exploring how these approaches can overcome the limitations associated with MLT's hemolytic activity and improve its selectivity and efficacy in targeting cancer cells. These advancements hold promise for the creation of innovative and enhanced therapeutic approaches based on MLT for the treatment of cancer.

Antiviral attributes of bee venom as a possible therapeutic approach against SARS-CoV-2 infection

The unprecedented scale of the SARS-CoV-2 pandemic has driven considerable investigation into novel antiviral treatments since effective vaccination strategies cannot completely eradicate the virus. Apitherapy describes the medicinal use of bee venom, which may be an effective treatment against SARS-CoV-2 infection. Bee venom contains chemicals that are antimicrobial and stimulate the immune system to counteract viral load. The present review focuses on the use of bee venom as a possible treatment for COVID-19 and reviews studies on the pharmacodynamics of bee venom.

Bio-nano scale modifications of melittin for improving therapeutic efficacy

INTRODUCTION

Melittin (MLT), a natural membrane-active component, is the most prominent cytolytic peptide from bee venom. Remarkable biological properties of MLT, including anti-inflammatory, antimicrobial, anticancer, anti-protozoan, and antiarthritic activities, make it an up-and-coming therapeutic candidate for a wide variety of human diseases. Therapeutic applications of MLT may be hindered due to low stability, high toxicity, and weak tissue penetration. Different bio-nano scale modifications hold promise for improving its functionality and therapeutic efficacy.

AREAS COVERED

In the current review, we aimed to provide a comprehensive insight into strategies used for MLT conjugations and modifications, cellular delivery of modified forms, and their clinical perspectives by reviewing the published literature on PubMed, Scopus, and Google Scholar databases. We also emphasized the MLT structure modifications, mechanism of action, and cellular toxicity.

EXPERT OPINION

Developing new analogs and conjugates of MLT as a natural drug with improved functions and fewer side effects is crucial for the clinical translation of this approach worldwide, especially where the chemicals and synthetic drugs are more expensive or unavailable in the healthcare system. MLT-nanoconjugation may be one of the best-optimized strategies for improving peptide delivery, increasing its therapeutic efficacy, and providing minimal nonspecific cellular lytic activity. [Figure: see text].

Melittin-Based Nano-Delivery Systems for Cancer Therapy

Melittin (MEL) is a 26-amino acid polypeptide with a variety of pharmacological and toxicological effects, which include strong surface activity on cell lipid membranes, hemolytic activity, and potential anti-tumor properties. However, the clinical application of melittin is restricted due to its severe hemolytic activity. Different nanocarrier systems have been developed to achieve stable loading, side effects shielding, and tumor-targeted delivery, such as liposomes, cationic polymers, lipodisks, etc. In addition, MEL can be modified on nano drugs as a non-selective cytolytic peptide to enhance cellular uptake and endosomal/lysosomal escape. In this review, we discuss recent advances in MEL’s nano-delivery systems and MEL-modified nano drug carriers for cancer therapy.

Bee venom and its active component Melittin synergistically potentiate the anticancer effect of Sorafenib against HepG2 cells

There are current attempts to find a safe substitute or adjuvant for Sorafenib (Sorf), the standard treatment for advanced hepatocellular carcinoma (HCC), as it triggers very harsh side effects and drug-resistance. The therapeutic properties of Bee Venom (BV) and its active component, Melittin (Mel), make them suitable candidates as potential anti-cancer agents per-se or as adjuvants for cancer chemotherapy. Hence, this study aimed to evaluate the combining effect of BV and Mel with Sorf on HepG2 cells and to investigate their molecular mechanisms of action. Docking between Mel and different tumor-markers was performed. The cytotoxicity of BV, Mel and Sorf on HepG2 and THLE-2 cells was conducted. Combinations of BV/Sorf and Mel/Sorf were performed in non-constant ratios on HepG2. Expression of major cancer-related genes and oxidative stress status was evaluated and the cell cycle was analyzed. The computational analysis showed that Mel can bind to and inhibit XIAP, Bcl2, MDM2, CDK2 and MMP12. Single treatments of BV, Mel and Sorf on HepG2 showed lower IC₅₀than on THLE-2. All combinations revealed a synergistic effect at a combination index (CI) < 1. Significant upregulation (p < 0.05) of p53, Bax, Cas3, Cas7 and PTEN and significant downregulation (p < 0.05) of Bcl-2, Cyclin-D1, Rac1, Nf-κB, HIF-1a, VEGF and MMP9 were observed. The oxidative stress markers including MDA, SOD, CAT and GPx showed insignificant changes, while the cell cycle was arrested at G2/M phase. In conclusion, BV and Mel have a synergistic anticancer effect with Sorf on HepG2 that may represent a new enhancing strategy for HCC treatment.

Bee Venom-A Potential Complementary Medicine Candidate for SARS-CoV-2 Infections

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is characterized by severe cytokine storm syndrome following inflammation. SARS-CoV-2 directly interacts with angiotensin-converting enzyme 2 (ACE-2) receptors in the human body. Complementary therapies that impact on expression of IgE and IgG antibodies, including administration of bee venom (BV), have efficacy in the management of arthritis, and Parkinson's disease. A recent epidemiological study in China showed that local beekeepers have a level of immunity against SARS-CoV-2 with and without previous exposure to virus. BV anti-inflammatory properties are associated with melittin and phospholipase A2 (PLA2), both of which show activity against enveloped and non-enveloped viruses, including H1N1 and HIV, with activity mediated through antagonist activity against interleukin-6 (IL-6), IL-8, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α). Melittin is associated with the underexpression of proinflammatory cytokines, including nuclear factor-kappa B (NF-κB), extracellular signal-regulated kinases (ERK1/2), and protein kinase Akt. BV therapy also involves group III secretory phospholipase A₂ in the management of respiratory and neurological diseases. BV activation of the cellular and humoral immune systems should be explored for the application of complementary medicine for the management of SARS-CoV-2 infections. BV "vaccination" is used to immunize against cytomegalovirus and can suppress metastases through the PLA2 and phosphatidylinositol-(3,4)-bisphosphate pathways. That BV shows efficacy for HIV and H1NI offers opportunity as a candidate for complementary therapy for protection against SARS-CoV-2.

Acid-Activated Melittin for Targeted and Safe Antitumor Therapy

Melittin (MLT), as a natural active biomolecule, can penetrate the tumor cell membrane to play a role in cancer treatment and will attract more attention in future development of antitumor drugs. The main component of natural bee venom MLT was modified by introducing a pH-sensitive amide bond between the 2,3-dimethyl maleimide (DMMA) and the lysine (Lys) of MLT (MLT-DMMA). MLT and its corresponding modified peptide MLT-DMMA were used for antitumor and biocompatibility validation. The biomaterial characteristics were tested by MALDI-TOF MS, ¹H NMR, IUPAC and HPLC, cell viability, hemolytic and animal experiment safety evaluation. Compared with the primary melittin, the modified peptide showed decreased surface charge and low cytotoxicity in physiological conditions. Moreover, cell assays confirmed the acid-activated conversion of amide bond resulting in adequate safety during delivery and timely antitumor activity in tumor lesions. Thus, MLT-DMMA provided a feasible platform to improve the targeted and safe antitumor applications.

Therapeutic Properties of Bioactive Compounds from Different Honeybee Products

Honeybees produce honey, royal jelly, propolis, bee venom, bee pollen, and beeswax, which potentially benefit to humans due to the bioactives in them. Clinical standardization of these products is hindered by chemical variability depending on honeybee and botanical sources, but different molecules have been isolated and pharmacologically characterized. Major honey bioactives include phenolics, methylglyoxal, royal jelly proteins (MRJPs), and oligosaccharides. In royal jelly there are antimicrobial jelleins and royalisin peptides, MRJPs, and hydroxy-decenoic acid derivatives, notably 10-hydroxy-2-decenoic acid (10-HDA), with antimicrobial, anti-inflammatory, immunomodulatory, neuromodulatory, metabolic syndrome preventing, and anti-aging activities. Propolis contains caffeic acid phenethyl ester and artepillin C, specific of Brazilian propolis, with antiviral, immunomodulatory, anti-inflammatory and anticancer effects. Bee venom consists of toxic peptides like pain-inducing melittin, SK channel blocking apamin, and allergenic phospholipase A2. Bee pollen is vitaminic, contains antioxidant and anti-inflammatory plant phenolics, as well as antiatherosclerotic, antidiabetic, and hypoglycemic flavonoids, unsaturated fatty acids, and sterols. Beeswax is widely used in cosmetics and makeup. Given the importance of drug discovery from natural sources, this review is aimed at providing an exhaustive screening of the bioactive compounds detected in honeybee products and of their curative or adverse biological effects.

Therapeutic arthropods and other, largely terrestrial, folk-medicinally important invertebrates: a comparative survey and review

Traditional healing methods involving hundreds of insect and other invertebrate species are reviewed. Some of the uses are based on the tenet of "similia similibus" (let likes be cured by likes), but not all non-conventional health promoting practices should be dismissed as superstition or wishful thinking, for they have stood the test of time. Two questions are addressed: how can totally different organ systems in a human possibly benefit from extracts, potions, powders, secretions, ashes, etc. of a single species and how can different target organs, e.g. bronchi, lungs, the urinary bladder, kidneys, etc. apparently respond to a range of taxonomically not even closely related species? Even though therapeutically used invertebrates are generally small, they nevertheless possess organs for specific functions, e.g. digestion, gas exchange, reproduction. They have a nervous system, endocrine glands, a heart and muscle tissue and they contain a multitude of different molecules like metabolites, enzymes, hormones, neurotransmitters, secretions, etc. that have come under increased scientific scrutiny for pharmacological properties. Bearing that in mind it seems likely that a single species prepared and used in different ways could have a multitude of uses. But how, for example, can there be remedies for breathing and other problems, involving earthworms, molluscs, termites, beetles, cockroaches, bugs, and dragonflies? Since invertebrates themselves can suffer from infections and cancers, common defence reactions are likely to have evolved in all invertebrates, which is why it would be far more surprising to find that each species had evolved its own unique disease fighting system. To obtain a more comprehensive picture, however, we still need information on folk medicinal uses of insects and other invertebrates from a wider range of regions and ethnic groups, but this task is hampered by western-based medicines becoming increasingly dominant and traditional healers being unable and sometimes even unwilling to transmit their knowledge to the younger generation. However, collecting and uncontrolled uses of therapeutic invertebrates can put undue pressure on certain highly sought after species and this is something that has to be borne in mind as well.

Anti-Inflammatory Applications of Melittin, a Major Component of Bee Venom: Detailed Mechanism of Action and Adverse Effects

Inflammation is a pervasive phenomenon triggered by the innate and adaptive immune systems to maintain homeostasis. The phenomenon normally leads to recovery from infection and healing, but when not properly phased, inflammation may cause immune disorders. Bee venom is a toxin that bees use for their protection from enemies. However, for centuries it has been used in the Orient as an anti-inflammatory medicine for the treatment of chronic inflammatory diseases. Bee venom and its major component, melittin, are potential means of reducing excessive immune responses and provide new alternatives for the control of inflammatory diseases. Recent experimental studies show that the biological functions of melittin could be applied for therapeutic use in vitro and in vivo. Reports verifying the therapeutic effects of melittin are accumulating in the literature, but the cellular mechanism(s) of the anti-inflammatory effects of melittin are not fully elucidated. In the present study, we review the current knowledge on the therapeutic effects of melittin and its detailed mechanisms of action against several inflammatory diseases including skin inflammation, neuroinflammation, atherosclerosis, arthritis and liver inflammation, its adverse effects as well as future prospects regarding the use of melittin.

Melittin induces human gastric cancer cell apoptosis via activation of mitochondrial pathway

AIM: To investigate the apoptotic effects of melittin on SGC-7901 cells via activation of the mitochondrial signaling pathway in vitro.

METHODS: SGC-7901 cells were stimulated by melittin, and its effect on proliferation and apoptosis of was investigated by methyl thiazolyl tetrazolium assay, morphologic structure with transmission electron microscopy, annexin-V/propidium iodide double-staining assay, measuring mitochondrial membrane potential (MMP) levels, and analyzing reactive oxygen species (ROS) concentrations were analyzed by flow cytometry. Cytochrome C (Cyt C), apoptosis-inducing factor (AIF), endonuclease G (Endo G), second mitochondria-derived activator of caspases (Smac)/direct IAP binding protein with low isoelectric point (Diablo), and FAS were analyzed by western blot. The expression of caspase-3 and caspase-8 was measured using activity assay kits.

RESULTS: Melittin was incubated at 1.0, 2.0, 4.0, or 6.0 μg/mL for 1, 2, 4, 6, or 8 h and showed a time- and concentration-dependent inhibition of SGC-7901 cell growth. Melittin induced SGC-7901 cell apoptosis, which was confirmed by typical morphological changes. Treatment with 4 μg/mL melittin induced early apoptosis of SGC-7901 cells, and the early apoptosis rates were 39.97% ± 3.19%, 59.27% ± 3.94%, and 71.50% ± 2.87% vs 32.63% ± 2.75% for 1, 2, and 4 h vs 0 h (n = 3, P < 0.05); the ROS levels were 616.53% ± 79.78%, 974.81% ± 102.40%, and 1330.94% ± 93.09% vs 603.74% ± 71.99% (n = 3, P < 0.05); the MMP values were 2.07 ± 0.05, 1.78 ± 0.29, and 1.16 ± 0.25 vs 2.55 ± 0.42 (n = 3, P < 0.05); caspase-3 activity was significantly higher compared to the control (5492.3 ± 321.1, 6562.0 ± 381.3, and 8695.7 ± 449.1 vs 2330.0 ± 121.9), but the caspase activity of the non-tumor cell line L-O2 was not different from that of the control. With the addition of the caspase-3 inhibitor (Ac-DEVD-CHO), caspase-3 activity was significantly decreased compared to the control group (1067.0 ± 132.5 U/g vs 8695.7 ± 449.1 U/g). The expression of the Cyt C, Endo G, and AIF proteins in SGC-7901 cells was significantly higher than those in the control (P < 0.05), while the expression of the Smac/Diablo protein was significantly lower than the control group after melittin exposure (P < 0.01). Ac-DEVD-CHO did not, however, have any effect on the expression of caspase-8 and FAS in the SGC-7901 cells.

CONCLUSION: Melittin can induce apoptosis of human gastric cancer (GC) cells through the mitochondria pathways, and it may be a potent agent in the treatment of human GC.

The Oligo Fucoidan Inhibits Platelet-Derived Growth Factor-Stimulated Proliferation of Airway Smooth Muscle Cells

In the pathogenesis of asthma, the proliferation of airway smooth muscle cells (ASMCs) is a key factor in airway remodeling and causes airway narrowing. In addition, ASMCs are also the effector cells of airway inflammation. Fucoidan extracted from marine brown algae polysaccharides has antiviral, antioxidant, antimicrobial, anticlotting, and anticancer properties; however, its effectiveness for asthma has not been elucidated thus far. Platelet-derived growth factor (PDGF)-treated primary ASMCs were cultured with or without oligo-fucoidan (100, 500, or 1000 µg/mL) to evaluate its effects on cell proliferation, cell cycle, apoptosis, and Akt, ERK1/2 signaling pathway. We found that PDGF (40 ng/mL) increased the proliferation of ASMCs by 2.5-fold after 48 h (p < 0.05). Oligo-fucoidan reduced the proliferation of PDGF-stimulated ASMCs by 75%-99% after 48 h (p < 0.05) and induced G₁/G₀ cell cycle arrest, but did not induce apoptosis. Further, oligo-fucoidan supplementation reduced PDGF-stimulated extracellular signal-regulated kinase (ERK1/2), Akt, and nuclear factor (NF)-κB phosphorylation. Taken together, oligo-fucoidan supplementation might reduce proliferation of PDGF-treated ASMCs through the suppression of ERK1/2 and Akt phosphorylation and NF-κB activation. The results provide basis for future animal experiments and human trials.

Three valuable peptides from bee and wasp venoms for therapeutic and biotechnological use: melittin, apamin and mastoparan

While knowledge of the composition and mode of action of bee and wasp venoms dates back 50 years, the therapeutic value of these toxins remains relatively unexploded. The properties of these venoms are now being studied with the aim to design and develop new therapeutic drugs. Far from evaluating the extensive number of monographs, journals and books related to bee and wasp venoms and the therapeutic effect of these toxins in numerous diseases, the following review focuses on the three most characterized peptides, namely melittin, apamin, and mastoparan. Here, we update information related to these compounds from the perspective of applied science and discuss their potential therapeutic and biotechnological applications in biomedicine.

Protective effects of melittin on tumor necrosis factor-α induced hepatic damage through suppression of apoptotic pathway and nuclear factor-kappa B activation

Melittin, a major polypeptide in honeybee venom, have been used to treat inflammatory disease. Various studies have demonstrated the anti-bacterial, anti-viral, anti-inflammatory and anticancer effects of bee venom and melittin. However, the precise mechanism of melittin in liver disease is not yet known. Apoptosis contributes to liver inflammation and fibrosis. Knowledge of the apoptotic mechanisms is important to develop new and effective therapies for treatment of cirrhosis. In the present study, we investigated the anti-apoptotic effect of melittin on tumor necrosis factor (TNF)-α/actinomycin (Act) D-induced apoptosis in hepatocytes. Our results show significant protection from DNA damage by melittin treatment compared with corresponding TNF-α/Act D-treated hepatocytes without melittin. Melittin inhibited TNF-α/Act D-induced activation of the caspase, bcl-2 family of proteins and poly ADP-ribose polymerase (PARP)-1. Our results also indicate that melittin decreased nuclear factor-kappa B (NF-κB) by degradation of phosphorylation of IκB kinase (p-IKK) and NF-κB DNA binding activity in TNF-α/Act D-treated hepatocytes. These results suggest that melittin possesses a potent suppressive effect on apoptotic responses in TNF-α/Act D-treated hepatocytes via the NF-κB pathway.

Melittin has an inhibitory effect on TNF-α-induced migration of human aortic smooth muscle cells by blocking the MMP-9 expression

Matrix metalloproteinases-9 (MMP-9) plays an important role in the pathogenesis of atherosclerosis and migration of vascular smooth muscle cells (VSMCs) after an arterial injury. In this study, we investigated the potential molecular mechanisms underlying the anti-atheroscleroic effects of melittin, a major component of bee venom, in human aortic smooth muscle cells (HASMCs). Melttin significantly suppressed MMP-9 and MMP-2 secretion, as well as TNF-α-induced MMP-9 expression in the HASMCs. In addition, we found that the inhibitory effects of melittin on TNF-α-induced MMP-9 protein expression are associated with the inhibition of MMP-9 transcription levels. Mechanistically, Melittin suppressed TNF-α-induced MMP-9 activity by inhibiting the phosphorylation of p38 and ERK1/2, but did not affect the phosphorylation of JNK and Akt. Reporter gene and western blotting assays showed that melittin inhibits MMP-9 transcriptional activity by blocking the activation of NF-κB via IκBα signaling pathway. Moreover, the matrigel migration assay showed that melittin reduced TNF-α-induced HASMC migration. These results suggest that melittin suppresses TNF-α-induced HASMC migration through the selective inhibition of MMP-9 expression and provide a novel role of melittin in the anti-atherosclerotic action.

Melittin inhibits atherosclerosis in LPS/high-fat treated mice through atheroprotective actions

AIM

Atherosclerosis is influenced by multiple environmental factors that involve a complex interaction between blood components and the arterial wall and is characterized by inflammatory reactions. Melittin has been used in treatment of various chronic inflammatory diseases. We investigated the effects of melittin regulated atherosclerotic changes in an animal model of atherosclerosis.

METHODS

Atherosclerotic mice were induced by intraperitoneal (i.p) injection of lipopolysaccharide (LPS, 2 mg/kg) three times a week and an atherogenic diet for 12 weeks.

RESULTS

Melittin (0.1 mg/kg) treatment was administered with i.p injection. Melittin treatment showed that total cholesterol and triglyceride levels decreased in atherosclerotic mice however, high-density lipoprotein cholesterol (HDL-C) levels were higher in atherosclerotic mice treated with melittin than in atherosclerotic mice. H&E staining showed that heart and descending aorta were significantly recovered by melittin, compared to atherosclerotic mice. In addition, melittin decreased the expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1, fibronectin and transforming growth factor (TGF)-β1 in atherosclerotic mice. In vitro, melittin decreased LPS-induced THP-1 cells-derived macrophages TNF-α and IL-1β expression levels and nuclear factor (NF)-κB signal pathway.

CONCLUSIONS

These results demonstrate that melittin has an anti-atherogenic effect by suppression of pro-inflammatory cytokines and adhesion molecules.

Bee (Apis mellifera) venom produced toxic effects of higher amplitude in rat thoracic aorta than in skeletal muscle--an ultrastructural study

In this study, changes produced in aorta and triceps surae muscle of Wistar rats as response to bee venom (BV) envenomation were analyzed by transmission electron microscopy and morphometry. A subchronic treatment of 30 days with daily doses of 700 μg BV/kg and an acute-lethal treatment with a single dose of 62 mg BV/kg were performed. The subchronic treatment resulted in endothelial cell retraction, a thicker subendothelial layer, and thinner elastic laminae and musculoelastic layers in aorta, and thicker endothelium and basal laminae in skeletal muscle. In both tissues polymorphous, swollen mitochondria with disrupted cristae were observed. The acute treatment produced extensive endothelial lesions, breakdown of the collagen layer and migration of muscle cells toward the intima in the aorta, and dilatation of endoplasmic reticulum in the skeletal muscle cells. Mitochondria were almost devoid of cristae or with few circular cristae in the smooth muscle cells while most of the mitochondria presented abnormal circular cristae in the skeletal muscle cells. Degenerative alterations in the aorta were of higher intensity in our experiments-both the intima and media strongly responded to BV, in contrast to those found at the level of the skeletal muscle cells where a moderate degenerative myopathy was recorded.

Role of growth factor receptor transactivation in high glucose-induced increased levels of Gq/11alpha and signaling in vascular smooth muscle cells

We have recently shown that high glucose increased the expression of Gq/11alpha, PLCbeta and mediated signaling in A10 vascular smooth muscle cells (VSMC). Since high glucose has been shown to increase growth factor receptor activation, we investigated the role of epidermal growth factor receptor (EGF-R) and platelet-derived growth factor receptor (PDGF-R) transactivation in high glucose-induced enhanced expression of Gq/11alpha and PLCbeta. Pre-treatment of A10 VSMC with high glucose (26 mM) for 3 days, increased the levels of Gqalpha, G11alpha, PLCbeta-1 and PLCbeta-2 proteins which were restored to control levels by AG1478, an inhibitor of EGF-R, AG1295, an inhibitor of PDGF-R and PP2, an inhibitor of c-Src but not by PP3. In addition, endothelin-1 (ET-1)-stimulated production of IP(3) that was enhanced by high glucose was also restored towards control levels by AG1478, AG1295 and PP2. High glucose also increased the phosphorylation of EGF-R and PDGF-R which was abolished by AG1478, AG1295 and PP2. Furthermore, high glucose-induced enhanced levels of Gqalpha, G11alpha and PLCbeta were also attenuated by PD98059, an inhibitor of mitogen-activated protein kinase (MAPK) and wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-K). In addition, AG1478 and AG1295, also attenuated high glucose-induced enhanced phosphorylation of ERK1/2 and AKT. Furthermore, high glucose augmented the phosphorylation of c-Src which was attenuated by antioxidant, DPI. These results suggest that oxidative stress through the activation of c-Src and resultant transactivation of growth factor receptor contributes to the high glucose-induced enhanced expression of Gq/11alpha/PLC and -mediated cell signaling through MAPK/PI3K pathway.