Current Medicinal Chemistry - Volume 19, Issue 1, 2012

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Peptic ulcer disease is a worldwide disease affecting 15-20% of the human population with an etiology that depends on regional and socioeconomic factors with the pathogenesis of this disorder remaining a mystery. In this issue of the journal, we have focused on the recent advances in the mechanism of gastrointestinal (GI) integrity, gastroprotection and ulcer healing that had recently triggered the attention of basic scientists and clinicians, due to the identification of novel and emerging pathways, thus shedding more light on the mechanism of protection, repair and ulcer healing within GI-tract. For a long time, it has been known that the gastric mucosa can withstand the natural attack of the acidified environment inside of the stomach. This is the so called mucosal barrier, a concept that was originally pioneered by Code and Davenport, and has resurfaced with the discovery of Helicobacter pylori, as well as other pathogenic and ulcer-causative mechanisms including the human ingestion of nonsteroidal anti-inflammatory drugs (NSAID). There are other risk factors of peptic ulcer disease such as smoking, alcohol, hiperosmolar solutions and bile salts refluxed from the duodenum. The physiological maintenance of the gastric mucosal integrity and the resistance to mucosal damage despite exposure to these factors is accomplished by the functional activity of the lines of mucosal defense such as the mucus-bicarbonate secretion, the undisturbed microcirculation, the presence of mucosal sulfhydryls and expression of heat shock proteins and defensines. Aside from Andre Roberts breakthrough principle that exogenous prostaglandins (PG) (direct cytoprotection) and endogenous PG (adaptive cytoprotection) are major gastroprotectants, there is now a consensus that CGRP/NO system together with PG represent a common final mechanism in gastroprotection against injury induced by various brain and appetite peptides such as TRH, ghrelin and leptin. In addition to stimulating or inhibit appetite, these peptides act locally to protect the gastric mucosa via increasing gastrointestinal microcirculation, as well as the activation of the brain-gut axis involving long a vagal loop to confer this protection. In contrast to short-term cytoprotection or gastroprotection, long-term ulcer healing is a complex process of tissue regeneration, which involves cell migration, proliferation from ulcer associated cell lineage (UCLA), re-epithalization, angiogenesis and vasculogenesis. Biochemistry of that process includes the comprehensive interplay between growth factors (EGF, bFGF, IGF-1) and the serum response factor (SRF) that activates early genes such as c-fos, egr-1/2, cyr 61 and cytoskeletal genes. The early microvascular damage due to hypoxia during the perpetuation of the gastric barrier triggers an expression of hypoxia inducible factor (HIF-1), which serves as hypoxia sensor and contributes to a compensatory and adaptive mechanism. A new promising avenues in the mucosal defense is gaseous mediators such as H2S and CO, which together with NO contribute to both the protection and ulcer healing of the GI mucosa, by stimulating bicarbonate secretion in response to duodenal acid. The role of these new gaseous mediators from old gaseous mediators, namely H2S and CO influencing the mechanism of mucosal protection and ulcer healing, constitutes a novel experimental approach that should be further elucidated and confirmed in humans. Hydrogen sulfide and CO combined with NSAID, which is similar to NO released from NSAID's seem to be the example of the preclinical utility of physiological gaseous mediators effective in counteracting adverse side effect such as gastric bleeding, and also those identified in the small intestine that were associated with the use of their parent NSAID. The incidence of small intestinal injury caused by NSAID supports the notion that NSAID-induced enteropathy cannot be considered exclusively as an acid-related disease. It also becomes evident that the bacterial flora and mitochondrial disorders may play a key role in small bowel injury induced by conventional NSAID. Since the injured gastric mucosa produces an abundant amount of Ang-(1-7), a novel concept is proposed that the local reninangiotensin system could contribute to the mechanism of protection and to the mucosal recovery from gastric lesions due to the fast and excessive biosynthesis of active metabolites of angiotensin I such as Ang-(1-7). This mechanism may also play an essential role in ulcer healing due to prominent enhancement in the gastric circulation induced by vasodilatory Ang-(1-7) metabolite. The mechanism of the pathogenic action of cigarette smoke, one of the important risk factors of the peptic ulcer involves a disturbance in the cell proliferation, inhibition of protective mucus secretion and an impairment of the formation of new microvessels (angiogenesis). Moreover, cigarette smoke interferes with the innate immune response during the process of repair and healing of the GI mucosa. Recent advances revealed that cigarette smoke and its extract can deregulate the function and apoptosis of endothelial cells by inhibiting NO production, reducing gastric mucosal PGE2 levels and impairing the angiogenic VEGF pathway. The involvement of physiological factors such as the specific GPCRs responsible for the chemosensing of proteins, L-amino acids, bile acids, fatty acids, and carbohydrates to the mechanism of GI-integrity should be further investigated. Taste receptors have a proposed role in the intestinal chemosensing, and there is an agreement that sweet, bitter, and umami evoke their responses in the gut via GPCRs. The GPCRs family of protein seems not be fully explored scientifically, especially with regards to the mucosal integrity, but identification of nutrient receptor agonists and antagonists can provide novel therapeutic targets for metabolic diseases, obesity, acid reflux and mucosal injury. This latter seems to be of importance for GI integrity since free radical biology studies revealed that the concentration of the reactive oxygen metabolites (ROS) in the gastric mucosa is about 1000-fold higher than that in other tissues or plasma. Generation of ROS contributes to exogenous injury to the gastric mucosa, including damage brought about by ethanol or nonsteroidal anti-inflammatory drugs (NSAIDs). Moreover, ROS play a major role in the multistep process leading to the development of gastric cancer. Interestingly, naturally occurring anti-oxidants called nutraceuticals including probiotics such as Lactobacilli, Saccharomyces bacteria or Bifidobacteria spp, were recently shown to exert a protective effect in the GI-tract mainly by the scavenging of oxygen and nitrogen free radicals breaking lipid chain peroxidation reaction. Beside probiotics this long list of protective nutraceuticals includes a variety of phytochemicals, flavonoids, curcumin, apple extracts, garlic and honey extracts. However, scientific validity of the use of a number of these products should be explored and rigorous research is warranted in order to identify the mechanism involved in the novel compounds to be used alone or in combination, perhaps as adjuvant therapy with standard drugs to treat gastrointestinal disorders. This issue of the journal prepared by experts in the field of gastroenterology gives an insight into the updated physiology and pharmacology of the exciting mechanisms by which GI mucosa can resist the injury, exerts protective response to noxious stimuli and heal in cases of ulcer development.

This paper reviews and updates current views on gastric mucosal injury with a focus on the microvascular endothelium as the key target and the role of the anti-apoptosis protein survivin. Under normal conditions, mucosal integrity is maintained by well structured and mutually amplifying defense mechanisms, which include pre-epithelial “barrier” - the first line of defense; and, an epithelial “barrier”. Other important defense mechanisms of gastric mucosa include: continuous epithelial cell renewal, blood flow through mucosal microvessels (providing oxygen and nutrients), an endothelial microvascular “barrier,” sensory innervation, and generation of PGs, nitric oxide and hydrogen sulfide. The microvascular endothelium lining gastric mucosal blood microvessels severs not only as a barrier but is a biologically active tissue involved in many synthetic and metabolic functions. It allows transport of oxygen and nutrients, and produces prostaglandins and leukotriens, procoagulant factors, nitric oxide, endothelin, ghrelin, HSP, growth factors such VEGF, bFGF, angiopoietin 2 and others, specific types of collagen, plasminogen activator, and can also actively contract. Accumulating evidence indicates that the gastric microvascular endothelium is a critical target for injury by ethanol, NSAIDs, free radicals, ischemiareperfusion and other damaging factors. The injury - microvessel rupture, plasma and erythrocyte extravasation, platelet aggregation and fibrin deposition caused by these damaging factors - occurs early (1-5 min), precedes glandular epithelial cell injury and results in cessation of blood flow, ischemia, hypoxia and impaired oxygen and nutrient transport. As a consequence, mucosal necrosis develops. One of the main reasons for the increased susceptibility of gastric microvascular endothelial (vs. epithelial) cells to injury is reduced expression levels of survivin, an anti-apoptosis protein, which is a regulator of both proliferation and cell survival.

In this paper we reviewed and updated current views on the cellular and molecular mechanisms of gastric and esophageal ulcer healing. Gastric ulcer healing encompasses inflammation, cell proliferation, epithelial regeneration, gland reconstruction, formation of granulation tissue, neovascularization (new blood vessel formation), interactions between various cells and the matrix and tissue remodeling, resulting in scar formation. All these events are controlled by the cytokines and growth factors, GI hormones including gastrin , CCK, and orexigenic peptides such as ghrelin, orexin-A and obestatin as well as Cox2 generated prostaglandins. These growth factors and hormones trigger cell proliferation, migration, and survival utilizing Ras, MAPK, PI-3K/AKT, PLC-γ and Rho/Rac/actin signaling pathways. Hypoxia triggers activation of some of these genes (e.g., VEGF) via hypoxia inducible factor (HIF). Growth factors: EGF, HGF, IGF-1, their receptors and Cox2 are important for epithelial cell proliferation, migration, re-epithelialization and regeneration of gastric glands during gastric ulcer healing. Serum response factor (SRF) is also essential for re-epithelialization and muscle restoration. VEGF, bFGF, angiopoietins, nitric oxide, endothelin, prostaglandins and metalloproteinases are important for angiogenesis, vascular remodeling and mucosal regeneration within gastric ulcer scar. SRF is critical limiting factor for VEGF-induced angiogenesis. Esophageal ulcer healing follows similar pattern to gastric ulcer, but KGF and its receptor are the key players in regeneration of the epithelium. In addition to local mucosal cells from viable mucosa bordering necrosis, circulating bone marrow derived stem and progenitor cells are potentially important for ulcer healing, contributing to the regeneration of epithelial and connective tissue components and neovascularization.

The field of gut nutrient chemosensing is evolving rapidly. Recent advances have uncovered the mechanism by which specific nutrient components evoke multiple metabolic responses. Deorphanization of G protein-coupled receptors (GPCRs) in the gut has helped identify previously unliganded receptors and their cognate ligands. In this review, we discuss nutrient receptors, their ligand preferences, and the evoked neurohormonal responses. Family A GPCRs includes receptor GPR93, which senses protein and proteolytic degradation products, and free fatty acid-sensing receptors. Short-chain free fatty acids are ligands for FFA2, previously GPR43, and FFA3, previously GPR41. FFA1, previously GPR40, is activated by long-chain fatty acids with GPR120 activated by medium- and long-chain fatty acids. The GPR119 agonist ethanolamide oleoylethanolamide (OEA) and bile acid GPR131 agonists have also been identified. Family C receptors ligand preferences include L-amino acids, carbohydrate, and tastants. The metabotropic glutamate receptor (mGluR), calcium-sensing receptor (CaR), and GPCR family C, group 6, subtype A receptor (GPRC6A) mediate L-amino acid-sensing. Taste receptors have a proposed role in intestinal chemosensing; sweet, bitter, and umami evoke responses in the gut via GPCRs. The mechanism of carbohydrate-sensing remains controversial: the heterodimeric taste receptor T1R2/T1R3 and sodium glucose cotransporter 1 (SGLT-1) expressed in L cells are the two leading candidates. Identification of specific nutrient receptors and their respective ligands can provide novel therapeutic targets for the treatment of diabetes, acid reflux, foregut mucosal injury, and obesity.

Earlier experimental studies indicated that the integrity of vagal pathway was required to confer gastric protection against damaging agents. Several peptides located in the brainstem initially identified to influence vagal outflow to the stomach, as assessed by electrophysiological approach or by vagal dependent alterations of gastric secretory and motor function, were investigated for their influence in the vagal regulation of the resistance of the gastric mucosa to injury. Thyrotropin releasing hormone (TRH), or its stable TRH analog, RX-77368, injected at low doses into the cisterna magna or the dorsal motor nucleus (DMN) was the first peptide reported to protect the gastric mucosa against ethanol injury through stimulation of vagal cholinergic pathways, inducing the release of gastric prostaglandins/ nitric oxide (NO) and the recruitment of efferent function of capsaicin sensitive afferent fibers containing calcitonin-gene related peptide (CGRP). Activation of endogenous TRH-TRH1 receptor signaling located in the brainstem plays a role in adaptive gastric protection against damaging agents. Since then, an expanding number of peptides, namely peptide YY, CGRP, adrenomedullin, amylin, glugacon-like peptide, opioid peptides acting on μ, δ1 or δ2 receptors, nocicpetin, nocistatin, ghrelin, leptin and TLQP-21, a peptide derived from VGF prohormone, have been reported to act in the brainstem to afford gastric protection against ethanol injury largely through similar peripheral effectors mechanisms than TRH. Therefore gastric prostaglandins and CGRP/NO pathways represent a common final mechanism through which brain peptides confer vagally mediated gastroprotection against injury. A better understanding of brain circuitries through which these peptides are released will provide new strategies to recruit integrated and multifaceted gastroprotective mechanisms.

The secretion of HCO3 - in the duodenum is increased by mucosal acidification, and this process is modulated by gas mediators such as nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO), in addition to prostaglandins (PGs). The secretion is increased by NOR3 (NO donor), NaHS (H2S donor), and CORM-2 (CO donor). The HCO3 - responses to NOR3 and CORM-2 are attenuated by indomethacin, while that to NaHS is mitigated by indomethacin and L-NAME as well as sensory deafferentation. NOR3 and CORM-2 increase mucosal PGE2 production, while H2S increases mucosal PGE2 content and luminal NO release. The HCO3 - response to mucosal acidification is attenuated by indomethacin, propargylglycine, and SnPP, each inhibiting PG, H2S and CO production, respectively. The acid-induced duodenal damage is worsened when either PG, H2S or CO is lacking. These findings suggest that 1) NO, H2S, and CO, generated endogenously or exogenously, stimulate HCO3 - secretion in the duodenum; 2) the stimulatory action of NO and CO is mediated, at least partly, by endogenous PGs, while that of H2S is mediated by PGs and NO as well as sensory neurons; 3) these gas mediators are involved in the local regulation of acid-induced HCO3 - secretion, in addition to endogenous PGs; 4) the acidinduced duodenal damage is worsened by agents inhibiting the endogenous production of NO, H2S or CO. It is assumed that these gas mediators play a role in maintaining the integrity of the duodenal mucosa by modulating the secretion of HCO3 -.

The term cytoprotection pioneered by Robert and colleagues has been introduced to describe the remarkable ability of endogenous and exogenous prostaglandins (PGs) to prevent acute gastric hemorrhagic lesions induced by noxious stimuli such as ethanol, bile acids, hiperosmolar solutions and nonsteroidal anti-inflammatory agents such as aspirin. Since that time many factors were implicated to possess gastroprotective properties such as growth factors including epidermal growth factor (EGF) and transforming factor alpha (TGFα), vasodilatory mediators such as nitric oxide (NO) and calcitonin gene related peptide (CGRP) as well as appetite gut hormones including gastrin and cholecystokinin (CCK), leptin and recently ghrelin. This protective action of gut peptides has been attributed to the release of PG but question remains whether another peptide angiotensin, the classic component of the systemic and local renin-angiotensin system (RAS) could be involved in the mechanism of gastric integrity and gastroprotection. After renin stimulation, the circulating angiotensin I is converted to angiotensin II (ANG II) by the activity of the Angiotensin Converting Enzyme (ACE). The ANG II acting via its binding to two major receptor subtypes the ANG type 1 (AT1) and type 2 (AT2) has been shown be activated during stress and to contribute to the pathogenesis of cold stress- and ischemia-reperfusion-induced gastric lesions. All bioactive angiotensin peptides can be generated not only in systemic circulation, but also locally in several tissues and organs. Recently the new functional components of RAS, such as Ang-(1-7), Ang IV, Ang-(1-12) and novel pathways ACE2 have been described suggesting the gastroprotective role for the novel ANG II metabolite, Ang-(1-7). The fact that Ang-(1-7) is produced in excessive amounts in the gastric mucosa of rodents and that pretreatment by Ang-(1-7) exhibits a potent gastroprotective activity against the gastric lesions induced by cold-restraint stress suggests that this and possibly other vasoactive metabolites of ANG II pathway could be involved in the mechanism of gastric integrity and gastroprotection. This review summarizes the novel gastroprotective factors and mechanisms associated with metabolic fate of systemic and local RAS activation with major focus to recent advancement in the angiotensin pathways in the gut integrity.

Ulceration in the gastrointestinal (GI) mucosa is a common disorder in humans. It has been shown that cigarette smoking is closely related to the increase of peptic ulcer and also plays an inhibitory role on ulcer healing. However, the underlying mechanisms by which cigarette smoke exerts these adverse effects remain largely unknown. It is perhaps partly due to the complexity of chemical compositions in the smoke and furthermore their pathological actions are largely undefined. In this review, we have highlighted the potential adverse effects of the toxic chemical components in cigarette smoke and summarized their possible mechanisms of actions on ulcer formation and healing in the GI tract. We also discuss in detail how cigarette smoke disturbs cell proliferation, influences mucus synthesis and secretion, delays blood vessel formation, and interferes the innate immune responses during ulceration and repair in the GI mucosa.

The pathogenesis of inflammatory bowel disease (IBD) is complicated and even several therapeutic strategies have been developed, they are not adequate for achieving mucosal remission in all IBD patients. Several reports have described the role of carbon monoxide (CO) in protection against chronic intestinal inflammation. CO has recently emerged as a potent immunomodulatory entity, anti-inflammatory agent, and homeostasis of physiological condition. CO reduces lipopolysaccharide-induced proinflammatory cytokines in macrophages via the effect of MAPK pathways. Interleukin-6, one of the important cytokines in the pathogenesis of IBD is also regulated by CO. Epithelial cell restitution is reported to be important factor to control IBD and CO has been reported to enhance colonic epithelial restitution through FGF15/19 expression in colonic myofibroblasts. CO also reduced mucosal damage and inflammation in several experimental animal colitis models such as interleukin-10-/- mouse model, TCRα-/- mouse model, dextran sodium sulfate colitis model, and trinitrobennzen sulfonic acid colitis model. Taken together, CO has anti-inflammatory and enhancement of restitution examined in vitro model and in vivo experimental colitis model. These results indicate that CO may have a potential to be one of the therapeutic strategies in IBD patients.

Small intestinal injury caused by non-steroidal anti-inflammatory drugs (NSAIDs) or aspirin is an epoch making topic in clinical field with the aid of new devices, capsule endoscopy and double balloon enteroscopy to look at small intestine directly. However, the injury has been reported in animals since more than 40 years ago. Proposed mechanisms are impairment of mucosal defense through inhibition of cyclooxygenase (COX) resulting in deficiency of prostaglandins, and mitochondrial disorder. Possible aggressive factors are NSAIDs/aspirin themselves, bile, and enterobacteria. Translocation of enterobacteria through the mucosa impaired integrity may be the first step of the injury. Bacterial lipopolysaccharides stimulate toll-like receptor-4 in macrophages, which increases proinflammatory cytokines through MyD88 signaling pathway. Finally neutrophils are activated and the small intestinal mucosa is injured with the attacks of NSAIDs/aspirin themselves, bile, and proteolytic enzymes and active oxygen species released by neutrophils. Candidates of treatment tools are prostaglandin derivatives, mucoprotective drugs, probiotics, and mitochondrial protective drugs such as metronidazole and cyclosporin A. Further clinical studies are needed to elucidate the effect in humans.

Recent advances in endoscopic techniques such as capsule endoscopy have revealed that aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) often cause mucosal lesions not only in the upper gastrointestinal tract, but also in the small intestine in humans. Gastric and duodenal lesions caused by NSAIDs can be treated with anti-secretory agents such as proton pump inhibitors or histamine H2-receptor antagonists; however, these drugs are ineffective in treating NSAID-induced lesions in the small intestine. Furthermore, there are few effective agents for the treatment of small intestinal lesions. Therefore, identification of effective therapies for the treatment of NSAID/aspirin-induced small intestinal lesions remains an urgent priority. In the present review, we focus on novel pharmacological treatments to prevent or reduce NSAID-induced intestinal lesions, i.e., 1) GI-sparing NSAIDs (NO- or H2S-NSAIDs, NSAIDs mixed with phosphatidylcholine); 2) anti-ulcer drugs such as mucosal protective agents (misoprostol, rebamipide, teprenone, etc.) and anti-secretory agents (lansoprazole, etc.); 3) antibiotics (metronidazole) and probiotics (Lactobacillus sp.); and 4) food constituents (lactoferrin and soluble dietary fibers). We surveyed data from clinical trials evaluating these novel treatments. Also reviewed herein were the pros and cons of the novel protective methods from the standpoint of safety, efficacy, convenience, and cost.

Vascular injury of esophageal and gastrointestinal mucosa caused by injurious and ulcerogenic factors leads to the cessation of blood flow, ischemia, and hypoxia and tissue necrosis in form of erosions or ulcers. The re-establishment of blood vessels through the process of angiogenesis - formation of new blood vessels - is critical for healing of tissue injury because is essential for delivery of oxygen and nutrients to the healing site. Hypoxia increases expression of hypoxia inducible factor (HIF-1), which serves as hypoxia sensor and activates compensatory and adaptive mechanisms. However, the molecular mechanisms and the role of HIF-1α in hypoxiadriven cellular and molecular events of angiogenesis in gastrointestinal injury healing have not been fully explored. The review discusses the novel molecular mechanisms of angiogenesis in gastric and esophageal mucosa with focus on HIF1α and VEGF interactions during healing of gastric mucosal injury and esophageal ulcers. HIF-1α is upregulated by gastric mucosal injury and esophageal ulcers; this upregulation correlates with VEGF gene activation and initiation of angiogenesis. The non-steroidal anti-inflammatory drugs (NSAIDs) interfere with hypoxia-induced HIF-1α accumulation, VEGF gene activation and angiogenesis through upregulation of von Hippel- Lindau (VHL) tumor suppressor, which activates degradation of HIF-1α protein. HIF-1α is a transcription factor that under hypoxic conditions, accumulates in endothelial cells and can bind to VEGF gene promoter and induce VEGF gene expression. In order to activate the VEGF gene, HIF-1α must be transported to the nucleus. Recent evidence implicates importins as key mechanism in this process.

The term “enterochromaffin cell” was introduced more than 100 years ago. The cells that are morphologically similar to the enterochromaffin cells have been referred to as “enterochromaffin-like cells”. One of the enterochromaffin-like cell populations in the oxyntic mucosa of stomach is known to produce and store histamine and chromogranin A, and referred to as ECL cells. The biology and the functional morphology and topology of the ECL cells have been extensively studied, since they were discovered 45 years ago. ECLcell histamine plays an important role in the regulation of gastric acid secretion, particularly in response to gastrin stimulation. The timecourse responses of ECL cells to gastrin include mobilization of histamine, hypertrophy, hyperplasia, dysplasia and formation of ECLcell carcinoids. The ECL cells are controlled by a complex regulatory system involving endocrine, paracrine and neural pathways. The physiological significance of ECL cells reflects the nature of their products such as histamine, chromogranin A-derived peptides, Reg protein and yet-unknown hormone.

Natural medicinal products have been used for millennia for the treatment of several ailments. Although many have been superseded by conventional pharmaceutical approaches, there is currently a resurgence in the interest in natural products by the general public and the use of complementary and alternative medicine is increasing rapidly in developed countries. Also, pharmaceutical industries are more and more interested in examining their potential as sources of novel medicinal compounds which may act as growth factor or show immunomodulatory or anti-microbial activity. The subgroup of natural bioactive compounds that bridge the gap between food products and drugs are termed nutraceuticals or functional foods. In contrast with most standard medicinal compounds, nutraceuticals are generally used to prevent rather than to treat disease. Many of the claims for such products are supported by very limited scientific evidence. However, there has recently been a great interest at evaluating the mechanism by which natural products exert their beneficial effects in the gastrointestinal tract. In particular, a major area of interest is for the use of biologically active chemical components of plants, i.e. phytochemicals, in a number of gastrointestinal disorders. While the major focus of phytochemical research has been on cancer prevention, several products of plant origin are being used and/or under study for a variety of other gastrointestinal problems. In this review we discuss the scientific evidence supporting the potential use of nutraceuticals as agents capable to prevent or accelerate healing of gastrointestinal mucosal damage, with a focus on polyphenol extracts obtained from apple.

Ghrelin, a peptide predominantly produced in the stomach exhibits numerous physiological functions, including stimulation of growth hormone release, food intake and gastric empting, and regulation of energy expenditure. This peptide exhibits also some protective and healing-promoting effects. This review summarizes the recent findings concerning animal and human data showing protective and therapeutic effects of ghrelin in the gut.

Stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, M.W. 1419) may be the new drug stable in human gastric juice, effective both in the upper and lower GI tract, and free of side effects. BPC 157, in addition to an antiulcer effect efficient in therapy of inflammatory bowel disease (IBD) (PL 14736) so far only tested in clinical phase II, has a very safe profile, and exhibited a particular wound healing effect. It also has shown to interact with the NO-system, providing endothelium protection and angiogenic effect, even in severely impaired conditions (i.e., it stimulated expression of early growth response 1 gene responsible for cytokine and growth factor generation and early extracellular matrix (collagen) formation (but also its repressor nerve growth factor 1- A binding protein-2)), important to counteract severe complications of advanced and poorly controlled IBD. Hopefully, the lessons from animal studies, particularly advanced intestinal anastomosis healing, reversed short bowel syndrome and fistula healing indicate BPC 157's high significance in further IBD therapy. Also, this supportive evidence (i.e., no toxic effect, limit test negative, LD1 not achieved, no side effect in trials) may counteract the problems commonly exercised in the use of peptidergic agents, particularly those used on a long-term basis.

Recent studies have revealed that chronic inflammation represents a major basis for different forms of human malignancies. Chronic inflammations are involved in the pathogenesis of 15-25% of human malignancies. Gastrointestinal (GI) cancer is one of the most common causes of mortality in the European Union. The mechanisms leading to cancer development and its progression are not completely understood. Advances are required both in early detection and therapy of GI cancers. There are many factors connecting inflammation and cancer. Cytokines that are small protein molecules regulating growth, differentiation, development and immune response mechanisms in cells. Overexpression of cyclooxynenase-2 is associated with decreased apoptosis, cell to cell adhesion, increased proliferation and angiogenesis contributes to the increased immunosuppresion and mediates carcinogenetic effects. MicroRNAs are regarded as a novel class of gene expression regulators. They are gene-silencing RNAs which negatively regulate gene expression. After binding to target mRNAs they lead either to mRNA destruction or inhibition of translation. Hence, they can play an important role in carcinogenesis. Currently, almost all of the miRNA-related studies on cancers based on the different expression profile of miRNAs in cancer cells compared to normal cells. In summary, miRNAs, proinflammatory cytokines and other factors, may be involved in cancer development based on chronic inflammation by controlling cell differentiation and apoptosis. Assessing the role of miRNAs will provide the new insights on their contribution to the link between chronic inflammation and subsequent cancer, and new markers for cancer diagnoses and cancer therapy.

Methylglyoxal is a reactive dicarbonyl compound produced from cellular glycolytic intermediates that reacts nonenzymatically with proteins to form products such as argpyrimidine at arginine residues. Abnormal accumulation of methylglyoxal and methylglyoxalderived advanced glycation end products (AGEs) occurs under hyperglycemic conditions and has been implicated in endothelium dysfunction, arterial stiffening, and microvascular complications in diabetes. However, the role of methylglyoxal in the healing process of diabetic gastric ulcers has not been fully investigated. Recently, methylglyoxal modification of peroxiredoxin-VI was found to be associated with delayed healing of diabetic gastric ulcers. Thus, inhibition of methylglyoxal modification might have therapeutic potential for the treatment of such ulcers. In this review, we present what is currently known regarding the role of methylglyoxal in the healing of diabetic gastric ulcers.

Malignant melanoma is a disease with high mortality rate caused by rapid metastasis. Cell motility is physically and biochemically restricted by cadherin-mediated cell interactions and signalling pathways, and alterations in cadherin expression strongly correlate with E to N-cadherin switch as well as the metastasis and progression of tumours. Contrary to E-cadherin, N-cadherin plays an important role in stimulating processes of cell division, migration, differentiation and death. In this study we investigated the role of N-cadherin in proliferation and AKT, ERK, beta-catenin signalling pathway in human melanoma cells: WM793(VGP), WM115(VGP) from the primary tumor site, as well as Lu1205(lung) and WM266-4(skin) from metastatic sites. N-cadherin, pAKT(S473), β-catenin, pERK1/2(T202/Y204), cyclin D1, cyclin D3, cyclin-dependent kinases CDK4, CDK6, and p15, p16, p21, p27 inhibitors expression was determined by western blot analysis. The study on proliferation of cells was performed with the use of BrdU incorporation and crystal violet staining assays. Knock-out of N-cadherin gene expression by siRNA process reduced the expression of: pAKT(S473), pERK1/2(T202/Y204), betacatenin, cyclin D1, cyclin D3 , cyclin-dependent kinases CDK4, CDK6 while increasing expression of cell cycle inhibitors p21 and p27, and significantly decreased cell proliferation (50-70%). The collected data indicate that N-cadherin mediates the effect of cell cycle in G1 phase by AKT, β-catenin, and ERK signalling pathway. These results suggest that increased expression of N-cadherin significantly contributes to the increased invasive potential of melanoma cells. Silencing of N-cadherin arrests cell growth at G1 phase and inhibits the entry into S-phase which is of great importance as to its possible future use in cancer treatment.