Sevelamer reverses liver fibrosis by deactivation of hepatic stellate cells.

Liver fibrosis is a chronic liver disease characterized by a progressive wound healing response caused by chronic liver injury. Currently, there are no approved clinical treatments for liver fibrosis. Sevelamer is used clinically to treat hyperphosphatemia and has shown potential therapeutic effects on liver diseases. However, there have been few studies evaluating the therapeutic effects of sevelamer on liver fibrosis, and the specific mechanisms are still unclear. In this study, we investigated the antifibrotic effects of sevelamer-induced low inorganic phosphate (Pi) stress in vitro and in vivo and analyzed the detailed mechanisms. We found that low Pi stress could inhibit the proliferation of activated hepatic stellate cells (HSCs) by promoting apoptosis, effectively suppressing the migration and epithelial-mesenchymal transition (EMT) of hepatic stellate cells. Additionally, low Pi stress significantly increased the antioxidant stress response. It is worth noting that low Pi stress indirectly inhibited the activation and migration of HSCs by suppressing transforming growth factor ß (TGF-ß) expression in macrophages. In a rat model of liver fibrosis, oral administration of sevelamer significantly decreased blood phosphorus levels, improved liver function, reduced liver inflammation, and increased the antioxidant stress response in the liver. Our study revealed that the key mechanism by which sevelamer inhibited liver fibrosis involved binding to gastrointestinal phosphate, resulting in a decrease in blood phosphorus levels, the downregulation of TGF-ß expression in macrophages, and the inhibition of HSC migration and fibrosis-related protein expression. Therefore, our results suggest that sevelamer-induced low Pi stress can attenuate hepatic stellate cell activation and inhibit the progression of liver fibrosis, making it a potential option for the treatment of liver fibrosis and other refractory chronic liver diseases.

Evaluation of the safety and efficacy of transarterial sevelamer embolization in a rabbit liver cancer model: A challenge on the size rule for vascular occlusion.

As the most efficient method to treat hepatocellular carcinoma in the immediate or advanced stage, transarterial chemoembolization (TACE) is coming into the era of microsphere (MP). Drug-eluting beads have shown their huge potential as an embolic agent and drug carrier for chemoembolization, but their sizes are strictly limited to be above 40 µm, which was considered to occlude vessels in a safe mode. microsphere smaller than 40 µm is easy to be washed out and transported to the normal liver lobe or other organs, causing severe adverse events and failed embolization. To determine whether sevelamer ultrafine particle (0.2-0.5 µm) is qualified as a safe and efficient embolic agent, we investigated the safety and therapeutic efficiency of transarterial sevelamer embolization (TASE) in the VX2 rabbit liver cancer model, aiming to challenge the "40 µm" rule on the selection criteria of the MP. In a four-arm study, blank bead (Callisphere, 100-300 µm), luminescent polystyrene microsphere (10, 100 µm), and sevelamer particle were transarterially administered to evaluate the threshold size of the MP size for intrahepatic or extrahepatic permeability. Another four-arm study was designed to clarify the safety and efficiency of preclinical transarterial sevelamer embolizationTASE tests over other techniques. Sham (saline), TASE, C-TACE, and D-TACE (n = 6) were compared in terms of serum chemistry, histopathology, and tumor necrosis ratio. In the first trials, the "40 µm" rule was detectable on the VX2 cancer model, but the regulation has no application to the new embolic agent as sevelamer ultrafine particles have not been found to leak out from the VX2 lesions, only found in the embolized vessels. Pathology proves that less viable tumor residue was found 2 weeks after the procedure, evidencing a better therapeutic outcome. No adverse events were found except for a short stress response. These results indicate that sevelamer is a safe and efficient embolic as an alternative to the current MP-based embolization therapy techniques.

Pi-inducedin-situaggregation of sevelamer nanoparticles for vascular embolization.

Decades have witnessed rapid progress of polymeric materials for vascular embolic or chemoembolic applications. Commercially available polymeric embolics range from gelatin foam to synthetic polymers such as poly(vinyl alcohol). Current systems under investigation include tunable, bioresorbable microspheres composed of chitosan or poly(ethylene glycol) derivatives,in situgelling liquid embolics with improved safety profiles, and radiopaque embolics that are trackablein vivo. In this paper, we proposed a concept of 'responsive embolization'. Sevelamer, clinically proved as an inorganic phosphate binder, was ground into nanoparticles. Sevelamer nanoparticle is highly mobile and capable of swelling and aggregating in the presence of endogenous inorganic phosphate, thereby effectively occluding blood flow in the vessel as it was administered as an embolic agent for interventional therapy. Moreover, citrated sevelamer nanoparticles delayed the aggregation, preferable to penetrate deeply into the capillary system. On the rabbit VX2 liver cancer model, both sevelamer particles aggregates occlude the tumor feeding artery, but backflow was found for the pristine one, thereby citrate passivation of sevelamer nanoparticles endows it have potential from 'bench to bedside' as a new type of vascular embolic.

Nanosized drug-eluting bead for transcatheter arterial chemoembolization (ND-TACE).

Commercially available drug-eluting embolization beads (100-500 µm) reduced the occurrence of adverse events related to an anticancer drug, but were unascertained to remarkably benefit the transcatheter arterial chemoembolization (TACE) treatment of intermediate-stage liver cancer. Dextran-coated arsenite nanoparticles with the size ranging from 400 to 600 nm were developed as a nanosized drug-eluting bead (NDEB) for chemoembolization therapy of the rabbit VX2 liver tumor. We fully characterized their relevant physicochemistry and drug release properties. Their hemolysis was investigated before vessel embolization. The introduction of the NDEB allowed continuous embolization of tumor feeding vessels and sustained release of arsenic trioxide, thereby causing severe tumor necrosis and reduced vascularity. Sonography including B mode ultrasound, color Doppler flow imaging (CDFI) and dynamic contrast-enhanced ultrasound (CEUS) were performed to evaluate the tumor vascularity and viability. Additionally, its hepatotoxicity was tolerable at a medium dose. NDEB-TACE might be an effective therapeutic strategy for interventional therapy.

Will Arsenic Trioxide Benefit Treatment of Solid Tumor by Nano- Encapsulation?

Arsenic trioxide (ATO) has remarkably enhanced therapeutic efficacy in treating both newly diagnosed and relapsed patients suffering from Acute Promyelocytic Leukemia (APL). Unfortunately, whether as a single agent, component of combined chemotherapy, or as a chemosensitizer or radiosensitizer combined with interventional therapy/radiotherapy, it did not benefit treatment of solid tumor (liver cancer, bladder cancer, glioma, breast cancer, cervical cancer, colorectal cancer, lung cancer, and melanoma) as seen from the clinical trials reported from the published journals or FDA-approved trials in the past decades. The clinical outcome failed to live up to our expectations, which was attributed to severe systemic toxicity and inappropriate pharmacokinetic such as low delivery efficiency and rapid renal elimination. Nanomedicine is designed to fuel up pharmaceuticals and polish off adverse effects by the moderation of their absorption, distribution, metabolism, and excretion. Nevertheless, quite a few nanodrugs (such as Doxil, Abraxane) were approved to be used clinically, and "from bench to bedside" it seems to be no easy way for most of them, such as nano-ATO. Encapsulating ATO into several types of nano-vehicles (liposome, polymer micelle, porous silicon, etc.), nano-TO can improve pharmacokinetic and become a prominent candidate to penetrate into tumor tissue, but so far no nano- ATO clinical trials have been approved around the world. On summarizing the clinical trials of ATO on solid tumor and preclinical study of nano-ATO, it is believed there is still a chance for ATO to play a critical co-helper in a comprehensive therapy to fight with solid tumor.

Effect of the imatinib treatment regimen on the postoperative prognosis of patients with high-risk gastrointestinal stromal tumors.

Background: Surgical resection is the standard treatment for localized and potentially resectable gastrointestinal stromal tumors (GISTs), If the postoperative pathology diagnosis indicates that patients are at high risk of recurrence, they should be treated with imatinib. Even though the introduction of imatinib substantially improved the outcome of GIST patients, it is unclear whether different imatinib treatment regimens affect patients' survival. Methods: This retrospective study included 120 patients who underwent tumor resection for high-risk GISTs between January 2009 and October 2018. The patients were divided into three groups: one group of patients received postoperative imatinib adjuvant therapy regularly (regular treatment group); the second group was not treated with imatinib until they were found to have disease progression (observation group); the third group was treated with postoperative imatinib adjuvant therapy irregularly (irregularly treatment group). The progression-free survival (PFS) and overall survival (OS) were compared between the three groups, and the prognostic risk factors were analysed by the Cox regression model. Results: The median PFS was 45 months (range: 25-59). The 3- and 5-year PFS values were 71.3% and 49.9%, respectively. The PFS in the regular group was longer than in the observation group and irregular group (P<0.001). The median OS was 59 months (range:47-78). The 3- and 5-year OS values were 91.6% and 84.2%, respectively. There were no differences in OS among the three groups (P=0.150). The extent of radical resection (P<0.001) and intraoperative tumor rupture (P=0.005) were independent prognostic factors influencing OS. Conclusions: Irregular administration of imatinib was associated with a worse PFS, but it did not affect the OS of patients with high-risk GISTs. Avoiding intraoperative tumor rupture and R0 resection were associated with better survival.

Oxygen plasma-fragmented KMnF3 nanoparticle benefits contrast enhancement for MRI of a patient-derived tumor xenograft model.

Magnetic nanoparticles (NPs) are emerging as promising candidates for the next generation of image contrast agents and their performance is largely dependent on physicochemical properties. In this paper, a new type of 'top-down' fabrication technique was developed to synthesize ultrasmall magnetic NPs as a contrast enhancer. In a detailed, home-made oxygen plasma generator, fragments of larger KMnF3 NPs (22 nm) were broken down into smaller (<5 nm) particles with enhanced hydrophilicity. As massive activated oxygen species were produced during the process, the plasma was able to severely etch the NPs, and vacuum UV light irradiated them heavily as well, leaving them with weak crystallinity, splitting them into ultrafine particles. Also their surface transformed from hydrophobic to hydrophilic by oxidizing the passivated ligand, evidenced by the spectroscopy and microscopy results. The fragmented NPs are characteristic of unprecedented high longitudinal relaxivity (r1 = 35.52 mM-1.s-1) and appropriate biocompatibility. In a healthy mouse, the ultrafine NPs did not exert observable toxicity, this was evaluated by histology of the main organs and hemogram analysis, including kidney and liver function analysis. More interestingly, the ultrasmall NPs had a very long circulation time, as its blood half-life was around 20 h. When applied as a contrast enhancer for MRI of the patient-derived tumor xenograft model, the accumulation of KMnF3 NPs within the tumor had an average of 12.13% ID per gram, which greatly shortened the relaxation time of the tumor. Therefore the control-to-noise ratio was significantly enhanced, relative to the same dosage of Gadopentetetic acid (Magvenist) (P < 0.001). Our primary results demonstrate that fragmentation of the NPs via our home-made oxygen plasma technique might be an effective route for fabricating ultrasmall NPs, and benefit their contrast effect when applied as MRI enhancers for clinical diagnosis of tumors.

Preclinical evaluation of severely defective manganese-based nanocrystal as a liver-specific contrast media for MR imaging: comparison with Gd-EOB-DTPA and MnDPDP.

Manganese-based (chemically formulated of KMnF3) nanocrystal was evaluated as a liver-specific contrast agent for MR imaging and its imaging performance was also compared with those of two commercial hepatobiliary contrast media (Gd-EOB-DTPA and MnDPDP). KMnF3 nanocrystal was post-treated using a plasma technique to cause severe defects, leading to appropriate water dispersibility and high relaxivity. Severely defective KMnF3 nanocrystal (SD-KMnF3) has characteristic high tolerance, as evidenced by cytotoxicity on the macrophage cell, and acute and subchronic toxicity on the healthy mouse. SD-KMnF3 showed better hepatic MR imaging as the T 1 relaxation time of the liver decreased to only 17% of the control group, compared to 22% of the control group for Gd-EOB-DTPA (P < 0.01) and 42% of the control group for MnDPDP (P < 0.001). As applied to MR imaging of the allograft orthotopic model of liver cancer, statistical studies demonstrated that SD-KMnF3 significantly improved the tumor's contrast-to-noise ratio, compared with Gd-EOB-DTPA (P < 0.01) and MnDPDP (P < 0.01) by spin-echo pulse sequence, and even better performance (P < 0.001) by gradient-echo sequence. Our findings indicate that SD-KMnF3 could serve as a hepatic contrast agent for imaging liver cancer such as hepatocarcinoma or metastatic lesions.

KLF2 inhibits cell growth via regulating HIF-1α/Notch-1 signal pathway in human colorectal cancer HCT116 cells.

The transcription factor Krüppel-like factor 2 (KLF2) has been shown to function as a tumor suppressor and regulate biological processes of cancer cells, such as cell growth, cell apoptosis and angiogenesis. However, the function and mechanism of KLF2 in colorectal cancer (CRC) is still unknown. In the present study, we show that the expression of KLF2 is diminished in a cohort of CRC cell lines. Also, KLF2 overexpression remarkably inhibits HCT116 and SW480 cell survival and proliferation. Moreover, cell death detection ELISA plus assay showed that KLF2 overexpression increased HCT116 cell proliferation. Caspase-3/7 activity also increased in HCT116 cells transfected with PcDNA3.1-KLF2. Further studies showed that KLF2 significantly suppresses the expression of Notch-1 and is dependent on the decline of the HIF-1α level. Most importantly, silencing Notch-1 expression or HIF-1α level both impair the action of KLF2 overexpression in CRC cells. Collectively, we demonstrated that KLF2 mediates CRC cell biological processes including cell growth and apoptosis via regulating the HIF-1α/Notch-1 signal pathway. These results indicated that KLF2 plays an important role in CRC and provided novel insight on the function of KLF2 in tumor progression.

A study of the age-related effects of lactational atrazine exposure.

A growing number of reports have demonstrated that the widely-used herbicide Atrazine (ATR) can cause injury to dopamine (DA) neurons, but the exact mechanism remains unclear. In this study, we examined the effects of lactational ATR exposure in Sprague-Dawley rats on dopaminergic neuron health later in life. Compared with control rats, rats exposed to ATR during a critical period of neural development showed decreased striatal DA content and increased rates of DA turnover. The expression of Monoamine oxidase (MAO), which is associated with DA degradation, was up-regulated, and the expression of Vesicular Monoamine Transporter 2 (VMAT2), which is associated with DA transport, was down-regulated. The expression of transcription factor Nuclear Receptor Related Factor 1 (Nurr1), which is associated with DA neuron development, was down-regulated. Increased age (6-12 months old) increased the statistical significance of the differences of the above indicators in the ATR-treated rats compared to the control rats (P<0.05). Taken together, our results indicate that ATR exposure during the critical neural development period causes a down-regulation of Nurr1, which in turn affects Nurr1 target genes, including MAO, VMAT2 and DAT, which are involved in DA degradation and transport. Reduced expression of these genes impairs the capacity for vesicular storage or reuptake of DA, causing decreased levels of striatal DA, which can ultimately lead to DA neuron injury. DA neuron injuries become more severe over time, which suggests that aging can synergistically promote the ATR-associated DA neuron injuries.

Fisetin suppresses malignant proliferation in human oral squamous cell carcinoma through inhibition of Met/Src signaling pathways.

Fisetin (3,7,3',4'-tetrahydroxyflavone) is a dietary flavonoid and has been indicated as a novel anti-cancer agent in several types of cancer cells. However, the mechanisms underlying the effect of fisetin in human oral squamous cell carcinoma (OSCC) remain unclear. Here, we report that fisetin significantly inhibits tumor cell proliferation and induces apoptosis in OSCC (UM-SCC-23 and Tca-8113) cancer cell lines. Further analysis demonstrates that fisetin also inhibits Met/Src signaling pathways using the PathScan® receptor tyrosine kinases (RTK) Signaling Antibody Array Kit. Fisetin resulted in decreased basal expression of Met and Src protein in UM-SCC-23 cancer cell lines, which validated by western blot. A student's t-test (two-tailed) was used to compare differences between groups. Furthermore, fisetin significantly inhibited the expression of a disintegrin and metalloproteinase 9 (ADAM9) protein in OSCC cells. Taken together, these results provide novel insights into the mechanism of fisetin and suggest potential therapeutic strategies for human OSCC by blocking the Met/Src signaling pathways.

The Effect of Exposure to Atrazine on Dopaminergic Development in Pubertal Male SD Rats.

Atrazine (ATR, 2-chloro-4-ethylamino-6-isopropylamino-s-triazine) is used worldwide as a herbicide, and its presence in the environment has resulted in documented human exposure. A lack of strong evidence for genetic heritability of idiopathic Parkinson's disease has focused attention on environmental toxicants in the disease etiology, particularly agrichemicals. Parkinson's disease is associated with advanced age and is characterized by the degeneration of dopaminergic neurons, but it is unclear whether specific neuronal damage could result from insults during development. The juvenile period is particularly vulnerable to environmental agent, therefore, we evaluated the effects of a 28-day exposure to ATR on the dopaminergic system in pubertal rats. Sprague-Dawley rats were treated orally with ATR at 50, 100, and 200 mg/kg bw, daily from postnatal days 27 to 54. In this study, we examined the hypothesis that pubertal exposure to ATR would disrupt the development of the nigrostriatal dopamine (DA) system. The content of DA and levodopa (L-DA) were examined in striatum samples by HPLC-FL, and the mRNA and protein expression of tyrosine hydroxylase, orphan nuclear hormone receptor (Nurr1), Nurr1 interacting protein (NuIP), and cyclin-dependent kinase inhibitors of the Cip̲Kip family (p57kip2) were examined in samples of the nigrostriatum by use of fluorescence Real-Time quantitative polymerase chain reaction (PCR). Exposure of juvenile rats to the high dose of ATR led to reduced levels of DA and L-DA, genes expression of NuIP, Nurr1, and p57kip2 in animals.

Exposure to atrazine during gestation and lactation periods: toxicity effects on dopaminergic neurons in offspring by downregulation of Nurr1 and VMAT2.

High atrazine (2-chloro-4-ethytlamino-6-isopropylamine-1,3,5-triazine; ATR) contents in the environment threaten the health conditions of organisms. We examined the effects of ATR exposure on Sprague-Dawley rats during gestation and on the dopaminergic neurons of offspring during lactation. Pregnant dams were orally treated with 0 mg/kg/day to 50 mg/kg/day of ATR from gestational day 5 to postnatal day 22. Afterward, neither offspring nor dams received ATR. Dopamine (DA) content was examined in striatum samples by HPLC-FL; the mRNA expressions of tyrosine hydroxylase (TH), orphan nuclear hormone (Nurr1), dopamine transporter (DAT), and vesicular monoamine transporter 2 (VMAT2) in the ventral midbrain samples were examined by fluorescence PCR when the offspring reached one year of age. After the pregnant rats were exposed to ATR, the DA concentrations and mRNA levels of Nurr1 were decreased in their offspring. Decreased Nurr1 levels were also accompanied by changes in the mRNA levels of VMAT2, which controls the transport and reuptake of DA.

Activation of the ERK1/2 signaling pathway during the osteogenic differentiation of mesenchymal stem cells cultured on substrates modified with various chemical groups.

The current study examined the influence of culture substrates modified with the functional groups -OH, -COOH, -NH2, and -CH3 using SAMs technology, in conjunction with TAAB control, on the osteogenic differentiation of rabbit BMSCs. The CCK-8 assay revealed that BMSCs exhibited substrate-dependent cell viability. The cells plated on -NH2- and -OH-modified substrates were well spread and homogeneous, but those on the -COOH- and -CH3-modified substrates showed more rounded phenotype. The mRNA expression of BMSCs revealed that -NH2-modified substrate promoted the mRNA expression and osteogenic differentiation of the BMSCs. The contribution of ERK1/2 signaling pathway to the osteogenic differentiation of BMSCs cultured on the -NH2-modified substrate was investigated in vitro. The -NH2-modified substrate promoted the expression of integrins; the activation of FAK and ERK1/2. Inhibition of ERK1/2 activation by PD98059, a specific inhibitor of the ERK signaling pathway, blocked ERK1/2 activation in a dose-dependent manner, as revealed for expression of Cbf α -1 and ALP. Blockade of ERK1/2 phosphorylation in BMSCs by PD98059 suppressed osteogenic differentiation on chemical surfaces. These findings indicate a potential role for ERK in the osteogenic differentiation of BMSCs on surfaces modified by specific chemical functional groups, indicating that the microenvironment affects the differentiation of BMSCs. This observation has important implications for bone tissue engineering.

[The effects of methionine and choline on the expression levels of CaMKII and CREB mRNA and proteins in rats exposed to lead].

OBJECTIVE: To study the effects of methionine and choline on the expression levels of CaMKII and CREB mRNA and proteins in hippocampus of rats exposed to lead. METHODS: Male SD rats were divided into five groups. (1) control group, (2) group exposed to lead+2 by drinking water with 0.40 g/L lead acetate, (3) group exposed to methionine and choline (1:1, 400 mg/kg), (4) group exposed to 0.40 g/L lead acetate plus methionine and choline (1:1, 100 mg/kg), (5) group exposed to 0.40 g/L lead acetate plus methionine and choline (1:1, 400 mg/kg). In 8 weeks after exposure, all rats were killed. Then CREB mRNA and CaMK II mRNA expression levels in hippocampus were detected by real-time PCR, CREB and CaMK II protein expression levels in hippocampus were measured by western blot assay. RESULTS: The expression levels (0.743 ± 0.185 and 0.729 ± 0.199) of CaMKII mRNA and CREB mRNA in the hippocampus of lead group were significantly lower than those (0.950 ± 0.238 and 0.901 ± 0.232) of control group (P < 0.05), also the expression levels (0.271 ± 0.045 and 0.212 ± 0.058) of CREB protein and pCREB protein in the hippocampus of lead group were significantly lower than those (0.319 ± 0.058 and 0.506 ± 0.125) of control group (P < 0.05). The expression levels (1.014 ± 0.210 and 1.126 ± 0.379) of CaMKII mRNA and the expression levels (1.029 ± 0.335 and 0.932 ± 0.251) of CREB mRNA in the hippocampus of 2 groups exposed to lead acetate plus methionine and choline were significantly higher than those of lead group (P < 0.05). The expression levels (0.407 ± 0.951 and 0.563 ± 0.178) of CREB protein and pCREB protein in the hippocampus of group exposed to lead acetate plus 400 mg/kg methionine and choline were significantly higher than those of lead group (P < 0.05). CONCLUSION: Methionine and choline could decrease the inhibition effects of lead on the expression of CaMKII and CREB mRNA or CREB and pCREB proteins in the hippocampus of rats.

Downregulation of connective tissue growth factor inhibits the growth and invasion of gastric cancer cells and attenuates peritoneal dissemination.

BACKGROUND: Connective tissue growth factor (CTGF) has been shown to be implicated in tumor development and progression. However, the role of CTGF in gastric cancer remains largely unknown. RESULTS: In this study, we showed that CTGF was highly expressed in gastric cancer tissues compared with matched normal gastric tissues. The CTGF expression in tumor tissue was associated with histologic grade, lymph node metastasis and peritoneal dissemination (P < 0.05). Patients with positive CTGF expression had significantly lower cumulative postoperative 5 year survival rate than those with negative CTGF expression (22.9% versus 48.1%, P < 0.001). We demonstrated that knockdown of CTGF expression significantly inhibited cell growth of gastric cancer cells and decreased cyclin D1 expression. Moreover, knockdown of CTGF expression also markedly reduced the migration and invasion of gastric cancer cells and decreased the expression of matrix metalloproteinase (MMP)-2 and MMP-9. Animal studies revealed that nude mice injected with the CTGF knockdown stable cell lines featured a smaller number of peritoneal seeding nodules than the control cell lines. CONCLUSIONS: These data suggest that CTGF plays an important role in cell growth and invasion in human gastric cancer and it appears to be a potential prognostic marker for patients with gastric cancer.

Cimetidine inhibits the adhesion of gastric cancer cells expressing high levels of sialyl Lewis x in human vascular endothelial cells by blocking E-selectin expression.

Cimetidine has been shown to have anti-metastatic activity and improves the survival of patients with colorectal cancer. One hypothesis is its modulation of the expression of the cell adhesion molecule by target organ endothelial cells. Because of the inconclusive results in clinical trials of gastric cancer, we investigated the effects of cimetidine on the adhesion of gastric cancer cells to activated endothelial cells and on the expression of some cell adhesion molecules. Human endothelial cells were pre-incubated with cimetidine for 6 h, incubated with the cytokine tumor necrosis factor for 4 h, and the endothelial surface expression of E-selectin was evaluated by flow cytometry, immunostaining and ELISA. Further, we investigated E-selectin mRNA expression by RT-PCR. Three gastric cancer cell lines (SGC-7901, MGC-803, BGC-823) and a normal gastric epithelial cell line, GES-1, were studied for the surface expression of sialyl Lewis x by flow cytometry and immunostaining. Adherence of CFSE-labeled gastric cancer cells and GES-1 cells to endothelial cell monolayers was determined. Cimetidine significantly reduced E-selectin expression of activated endothelial cells, but did not influence E-selectin expression at the mRNA level. Three gastric cancer cell lines expressed high levels of sialyl Lewis x, whereas GES-1 did not. Cimetidine also significantly decreased gastric cancer cell adherence to stimulated endothelial cells. The inhibition of E-selectin expression corresponded to the reduction of tumor cell adherence. The effects of cimetidine on tumor adhesion were almost nullified by pre-incubation with E-selectin and sialyl Lewis x antibody. Furthermore, there was no significant change of GES-1 adherence to endothelial cells by TNF-α, cimetidine, E-selectin and sialyl Lewis x antibody. The inhibiton of gastric cancer cell adherence to cytokine-stimulated endothelial cells treated with cimetidine appears to result from blocking endothelial E-selectin expression. These data support the hypothesis that cimetidine may exert its anti-metastatic effects in gastric cancer, in part, by inhibiting E-selectin/sialyl Lewis x-mediated adherence of gastric cancer cells to endothelial cells in the metastasis target organs.