Feed-forward activation of STAT3 signaling limits the efficacy of c-Met inhibitors in esophageal squamous cell carcinoma (ESCC) treatment

c-Hepatocyte growth factor receptor (Met) inhibitors have demonstrated clinical benefits in some types of solid tumors. However, the efficacy of c-Met inhibitors in esophageal squamous cell carcinoma (ESCC) remains unclear. In this study, we discovered that c-Met inhibitors induced "Signal Transducer and Activator of Transcription (STAT3)-addiction" in ESCC cells, and the feedback activation of STAT3 in ESCC cells limits the tumor response to c-Met inhibition. Mechanistically, c-Met inhibition increased the autocrine of several cytokines, including CCL2, interleukin 8, or leukemia inhibitory factor, and facilitated the interactions between the receptors of these cytokines and Janus Kinase1/2 (JAK1/2) to resultantly activate JAKs/STAT3 signaling. Pharmacological inhibition of c-Met together with cytokines/JAKs/STAT3 axis enhanced cancer cells regression in vitro. Importantly, combined c-Met and STAT3 inhibitors synergistically suppressed tumor growth and promoted the apoptosis of tumor cells without producing systematic toxicity. These findings suggest that inhibition of the STAT3 feedback loop may augment the response to c-Met inhibitors via the STAT3-mediated oncogene addiction in ESCC cells.

Gut Organoid as a New Platform to Study Alginate and Chitosan Mediated PLGA Nanoparticles for Drug Delivery

Intestinal organoids can be used as an ex vivo epithelial model to study different drug delivery effects on epithelial cells’ luminal surface. In this study, the impact of surface charge on the delivery of 5-ASA loaded PLGA nanoparticles into the lumen of organoids was investigated. Alginate and chitosan were used to coat the nanoparticles and provide negative and positive charges on the particles, respectively. The organoid growth and viability were not affected by the presence of either alginate- or chitosan-coated nanoparticles. It was shown that nanoparticles could be transported from the serosal side of the organoids to the lumen as the dye gradually accumulated in the lumen by day 2–3 after adding the nanoparticles to the Matrigel. By day 5, the dye was eliminated from the lumen of the organoids. It was concluded that the positively charged nanoparticles were more readily transported across the epithelium into the lumen. It may be attributed to the affinity of epithelial cells to the positive charge. Thus, the organoid can be utilized as an appropriate model to mimic the functions of the intestinal epithelium and can be used as a model to evaluate the benefits of nanoparticle-based drug delivery.

Mesenchymal stem cell-derived interleukin-28 drives the selection of apoptosis resistant bone metastatic prostate cancer

Bone metastatic prostate cancer (PCa) promotes mesenchymal stem cell (MSC) recruitment and their differentiation into osteoblasts. However, the effects of bone-marrow derived MSCs on PCa cells are less explored. Here, we report MSC-derived interleukin-28 (IL-28) triggers prostate cancer cell apoptosis via IL-28 receptor alpha (IL-28Rα)-STAT1 signaling. However, chronic exposure to MSCs drives the selection of prostate cancer cells that are resistant to IL-28-induced apoptosis and therapeutics such as docetaxel. Further, MSC-selected/IL-28-resistant prostate cancer cells grow at accelerated rates in bone. Acquired resistance to apoptosis is PCa cell intrinsic, and is associated with a shift in IL-28Rα signaling via STAT1 to STAT3. Notably, STAT3 ablation or inhibition impairs MSC-selected prostate cancer cell growth and survival. Thus, bone marrow MSCs drive the emergence of therapy-resistant bone metastatic prostate cancer yet this can be disabled by targeting STAT3.

Pharmacological inhibition of STAT3 by BP-1-102 inhibits intracranial aneurysm formation and rupture in mice through modulating inflammatory response

As an inhibitor of STAT3, BP-1-102 can regulate the inflammation response caused by vascular smooth muscle cells (VSMCs) by inhibiting the JAK/STAT3/NF-κB pathway, thereby attenuating the symptoms of intracranial aneurysm (IA). IA mouse model was established by stereotactic injection of elastase to evaluate the effect of BP-1-102. The expression levels of smooth muscle markers and matrix metalloproteinases (MMPs) were detected by qRT-PCR, and the levels of inflammatory factors were detected by ELISA and qRT-PCR. The protein levels of the NF-κB signaling pathway factors were examined by Western blot. BP-1-102 reduced blood pressure in aneurysm mice, up-regulated smooth muscle cell markers MHC, SMA, and SM22, and down-regulated the expression of MMP2 and MMP9 in vascular tissues. At the same time, BP-1-102 also down-regulated the expression levels of inflammatory response factors and the NF-κB pathway proteins. In the IA model, BP-1-102 can reduce the expression of inflammatory factors and MMPs bound to NF-κB by inhibiting the activation of the JAK/STAT3/NF-κB pathway proteins, and then restore the vascular wall elastin to reduce blood pressure, thereby treating aneurysm.

N-Acetyl cysteine prevents activities of STAT3 inhibitors, Stattic and BP-1-102 independently of its antioxidant properties

BACKGROUND

Inhibitors for signal transducer and activator of transcription 3 (STAT3), Stattic, BP-1-102, and LLL12 significantly induce apoptosis in transformed Ba/F3 cells expressing an oncogenic fusion protein, nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) that induces the activation of STAT3. We found that the antioxidant reagent, N-acetyl cysteine (NAC) prevented the abilities of Stattic and BP-1-102, but not LLL12 to induce apoptosis in transformed cells expressing NPM-ALK, providing a novel problem in use of STAT3 inhibitors. We herein investigated the mechanisms how NAC prevented the effects of Sttatic and BP-1-102.

METHODS

Ba/F3 cells expressing NPM-ALK and SUDHL-1 cells were treated with antioxidants such as NAC, Trolox or edaravone in combination with STAT3 inhibitors. Phosphorylation of STAT3, cell proliferation rate, cell viability, cell cycle, internucleosomal DNA fragmentation and the intracellular accumulation of reactive oxygen species (ROS) was investigated. The binding of STAT3 inhibitors and NAC was analyzed by LC-MS.

RESULTS

NAC but not Trolox and edaravone diminished the abilities of Stattic and BP-1-102 to induce apoptosis in cells expressing NPM-ALK. The ROS levels in cells expressing NPM-ALK were not markedly affected by the treatments with Stattic and BP-1-102 in combination with NAC, suggesting that NAC inhibited the activity of Stattic and BP-1-102 independent of its antioxidant activity. LC-MS analysis revealed that NAC directly bound to Stattic and BP-1-102. Furthermore, these NAC adducts exhibited no cytotoxicity, and failed to affect the activity of STAT3.

CONCLUSIONS

NAC antagonizes the activities of Stattic and BP-1-102, which inhibit STAT3 activation by interacting with cysteine residues in STAT3.

Inhibition of EGFR-STAT3 attenuates cardiomyopathy in streptozotocin-induced type 1 diabetes

Emerging evidence implicates elevated activity of STAT3 transcription factor in driving the development and progression of diabetic cardiomyopathy (DCM). We hypothesized that the fibrosis-promoting and hypertrophic actions of STAT3 are linked to the activation by epidermal growth factor receptor (EGFR). We tested this hypothesis by challenging cultured cardiomyocytes to high-concentration glucose and heart tissues of streptozotocin (STZ)-induced type 1 diabetic mice. Our results indicated that, in diabetic mice, the blockade of STAT3 or EGFR using selective inhibitors S3I-201 and erlotinib, respectively, abrogated the increased activating STAT3 phosphorylation and the induction of genes regulating fibrosis and hypertrophy in myocardial tissue. S3I-201 and erlotinib significantly reduced myocardial structural and functional deficits in diabetic mice. In cultured cardiomyocytes, high-concentration glucose induced EGFR-mediated STAT3 phosphorylation. We further showed that blockade of STAT3 or EGFR using selective inhibitors and siRNAs significantly reduced the increased expression of genes known to promote fibrosis and hypertrophy in cardiomyocytes. These results provide novel evidence that the EGFR-STAT3 signaling axis likely plays a crucial role in the development and progression of DCM.

Cross-resistance of isoniazid, para-aminosalicylic acid and pasiniazid against isoniazid-resistant Mycobacterium tuberculosis isolates in China

OBJECTIVES

Pasiniazid is a chemical complex of isoniazid (INH) and para-aminosalicylic acid (PAS). The aim of this study was to explore the cross-resistance of INH, PAS and pasiniazid against INH-resistant Mycobacterium tuberculosis isolates in China.

METHODS

A Microplate alamarBlue® Assay was performed to determine the minimum inhibitory concentrations (MICs) of INH, PAS and pasiniazid against 109 INH-resistant M. tuberculosis isolates. A statistical analysis of the relationship between different genotypes, gene mutations, and INH, PAS or pasiniazid susceptibility was then performed.

RESULTS

Among the 109 INH-resistant isolates, 13 (11.9%) and 21 (19.3%) showed resistance to PAS and pasiniazid, respectively. Among the 13 PAS-resistant M. tuberculosis isolates, 11 remained susceptible to pasiniazid. Of 63 INH-resistant isolates harbouring mutations in katG, the inhA promoter or the oxyR-ahpC intergenic region, 52 remained susceptible to pasiniazid. Moreover, 11 of 13 pasiniazid-resistant isolates carried mutations in katG, the inhA promoter or the oxyR-ahpC intergenic region.

CONCLUSION

Taken together, these results demonstrate that PAS resistance and mutations in thekatG gene, inhA promoter or oxyR-ahpC intergenic region in INH-resistant M. tuberculosis have little effect on pasiniazid susceptibility.

Anticancer Activity of Water-Soluble Olsalazine-PAMAM-Dendrimer-Salicylic Acid-Conjugates

Improving the activity and selectivity profile of anticancer agents will require designing drug carrier systems that employ soluble macromolecules. Olsalazine-PAMAM-dendrimer-salicylic acid-conjugates with dendritic arms of different lengths have shown good stability regarding the chemical link between drug and spacer. In this study, the drug release was followed in vitro by ultraviolet (UV) studies. Evaluation of the cytotoxicity of the olsalazine-PAMAM-dendrimer-salicylic acid-conjugates employing a sulforhodamine B (SRB) assay in PC-3 (human prostatic adenocarcinoma) and MCF-7 (human mammary adenocarcinoma) cell lines demonstrated that conjugate 9 was more active as an antiproliferative agent than cisplatin, and no cytotoxicity towards the African green monkey kidney fibroblast (COS-7) cell line was observed in any of the conjugates synthesized in the present work.

HMGB1 knock-down promoting tumor cells viability and arrest pro-apoptotic proteins via Stat3/NFκB in HepG2 cells

BACKGROUND/AIM

High mobility group box 1 protein (HMGB1) is functionally dynamic and pleiotropic molecule, it has the potential to promote both cell survival and death by regulating multiple signaling pathways, including inflammation and apoptosis. This study aimed at investigating the role of silencing HMGB1 on tumor cells apoptosis and pro-inflammatory proteins expression in hepatocellular HepG2 cancer cells.

METHODS

HepG2 cells was transfected with si-RNA HMGB1, and the effect on pro-apoptotic proteins expressions like Bax, Bcl2, and pro-inflammatory cytokines like, p65-NFκB, and Cyclooxygenase-2 (Cox2) was assessed using western blot, and also cells apoptosis and proliferation was assessed using annexin V FITC and Calcien AM expression in flow cytometry and fluorescence.

RESULTS

HMGB1 silencing was found significantly increase tumor cells viability with significant decrease of pro-apoptotic proteins, also antiapoptotic protein Bcl2 was significantly up-regulated, which suggests a possible role in restricting apoptosis. Furthermore, HMGB1 knocked down found to inhibit Stat3 phosphorylation and significantly affect NFkB p65/Cox2 expression which suggests a link between HMGB1 and Stat3 activation. Our results revealed that HMGB1 knocked down may suppress cells apoptosis and enhance HepG2 cells viability via NFkB/Cox2 and Stat3. © 2018 BioFactors, 44(6):570-576, 2018.

Disrupting interaction of PSD-95 with nNOS attenuates hemorrhage-induced thalamic pain

Hemorrhages occurring within the thalamus lead to a pain syndrome. Clinical treatment of thalamic pain is ineffective, at least in part, due to the elusive mechanisms that underlie the induction and maintenance of thalamic pain. The present study investigated the possible contribution of a protein-protein interaction between postsynaptic density protein 95 (PSD-95) and neuronal nitric oxide synthase (nNOS) to thalamic pain in mice. Thalamic hemorrhage was induced by microinjection of type IV collagenase into unilateral ventral posterior medial/lateral nuclei of the thalamus. Pain hypersensitivities, including mechanical allodynia, heat hyperalgesia, and cold allodynia, appeared at day 1 post-microinjection, reached a peak 5-7 days post-microinjection, and persisted for at least 28 days post-microinjection on the contralateral side. Systemic pre-treatment (but not post-treatment) of ZL006, a small molecule that disrupts PSD-95-nNOS interaction, alleviated these pain hypersensitivities. This effect is dose-dependent. Mechanistically, ZL006 blocked the hemorrhage-induced increase of binding of PSD-95 with nNOS and membrane translocation of nNOS in thalamic neurons. Our findings suggest that the protein-protein interaction between PSD-95 and nNOS in the thalamus plays a significant role in the induction of thalamic pain. This interaction may be a promising therapeutic target in the clinical management of hemorrhage-induced thalamic pain.

ZL006, a small molecule inhibitor of PSD-95/nNOS interaction, does not induce antidepressant-like effects in two genetically predisposed rat models of depression and control animals

N-methyl-D-aspartate receptor (NMDA-R) antagonists and nitric oxide inhibitors have shown promising efficacy in depression but commonly induce adverse events. To circumvent these, a more indirect disruption of the nitric oxide synthase/postsynaptic density protein 95 kDa complex at the NMDA-R has been proposed. This disruption can be achieved using small molecule inhibitors such as ZL006, which has attracted attention as ischemic stroke therapy in rodents and has been proposed as a potential novel treatment for depression. Based on this, our aim was to translate these findings to animal models of depression to elucidate antidepressant-like properties in more detail. In the present study, we administered ZL006 to two established animal models of depression and control rodents. Following treatment, we measured locomotion in the Open Field and depressive-like behavior in the Forced Swim Test and Tail Suspension Test. Our experimental designs included the use of different species (rats, mice), strains (Flinders Sensitive Line rats, Flinders Resistant Line rats, Wistar Kyoto rats, Wistar Hanover rats, Sprague Dawley rats, B6NTac mice), routes of administration (intraperitoneal, intracerebroventricular), times of administration (single injection, repeated injections), treatment regimens (acute, sustained), and doses (5, 10, 15, 50 mg/kg). ZL006 did not affect behavior in any of the described settings. On a molecular level, ZL006 significantly reduced total nitrate/nitrite concentrations in the cerebellum, supporting that it is capable of reducing nitric oxide metabolites in the brain. Future studies using different experimental parameters are needed to further investigate the behavioral profile of ZL006.

Platelet-derived growth factor BB enhances osteoclast formation and osteoclast precursor cell chemotaxis

Enhanced osteoclast formation increases bone resorption, which triggers bone remodeling. Platelet-derived growth factor BB (PDGF-BB) enhances precursor cell homing, angiogenesis, and bone healing, and thereby could also treat osteoporosis. However, the effect of PDGF-BB on osteoclast formation is not fully understood. We investigated whether exogenous recombinant PDGF-BB directly affects osteoclast formation and osteoclast precursor cell chemotaxis. The murine monocyte-macrophage cell line RAW264.7 and bone-marrow-derived macrophages were cultured with recombinant mouse PDGF-BB with or without a platelet-derived growth factor receptor β inhibitor (AG-1295) or a Janus kinase 2 inhibitor (AG-490) to analyze the effect on osteoclastogenesis in vitro. PDGF-BB with or without AG-490 or AG-1295 was locally administrated in the mandibular fracture of 16-week-old Sprague Dawley rats (n = 18) for 1-2 weeks to analyze the effect on osteoclastogenesis in vivo. The effect of the treatments on osteoclast formation, osteoclast precursor cell migration, and expression of osteoclastogenic signaling molecules was analyzed. PDGF-BB enhanced osteoclast formation both in vitro and in vivo, but AG-490 and AG-1295 inhibited this effect. PDGF-BB enhanced phosphorylation of extracellular-signal-regulated kinase 1/2 (ERK1/2), Akt, and signal transducer and activator of transcription 3 (STAT3) in RAW264.7 cells. AG-490 inhibited PDGF-BB-induced STAT3 phosphorylation. PDGF-BB enhanced RAW264.7 cell migration and gene expression of osteoclastogenic signaling molecules (i.e., nuclear factor of activated T cells 1, dendrocyte-expressed seven transmembrane protein, and B-cell lymphoma 2), and treatment with AG-1295, AG-490, or S3I-201 (a STAT3 inhibitor) reduced this effect. PDGF-BB enhanced osteoclast formation, osteoclast precursor cell chemotaxis, and phosphorylation of STAT3, Akt, and ERK1/2. but AG-1295 and AG-490 reduced this effect. These findings reflect the complexity of PDGF-BB in bone biology.

ZL006 protects spinal cord neurons against ischemia-induced oxidative stress through AMPK-PGC-1α-Sirt3 pathway

Spinal cord ischemia (SCI) induces a range of cellular and molecular cascades, including activation of glutamate receptors and downstream signaling. Post-synaptic density protein 95 (PSD-95) links neuronal nitric oxide synthase (nNOS) with the N-methyl-d-aspartic acid (NMDA) receptors to form a ternary complex in the CNS. This molecular complex-mediated cytotoxicity has been implicated in brain ischemia, but its role in SCI has not been determined. The goal of the study was to investigate the potential protective effects of ZL006, a small-molecule inhibitor of the PSD-95/nNOS interaction, in an in vitro SCI model induced by oxygen and glucose deprivation (OGD) in cultured spinal cord neurons. We found that ZL006 reduced OGD-induced lactate dehydrogenase (LDH) release, neuronal apoptosis and loss of cell viability. This protection was accompanied by the preservation of mitochondrial function, as evidenced by reduced mitochondrial oxidative stress, attenuated mitochondrial membrane potential (MMP) loss, and enhanced ATP generation. In addition, ZL006 stimulated mitochondrial enzyme activities and SOD2 deacetylation in a Sirt3-dependent manner. The results of western blot analysis showed that ZL006 increased the activation of AMPK-PGC-1α-Sirt3 pathway, and the beneficial effects of ZL006 was partially abolished by AMPK inhibitor and PGC-1α knockdown. Therefore, our present data showed that, by the AMPK-PGC-1α-Sirt3 pathway, ZL006 protects spinal cord neurons against ischemia through reducing mitochondrial oxidative stress to prevent apoptosis.

[Hypoxia combined with TNF-α induces apoptosis of cultured human pulmonary microvascular endothelial cells via activation of the STAT3 rather than ERK1/2 signaling pathway]

Objective To explore the effect of combined hypoxia and tumor necrosis factor α (TNF-α) on the apoptosis of human pulmonary microvascular endothelial cells (HPMVECs) and the involved signaling pathway mechanism. Methods Some HPMVECs were treated with hypoxia within 6, 12, or 24 hours, and the other cells were treated with TNF-α at the concentrations of 10, 20, 50, or 100 ng/mL. Cell activity was determined by MTT assay in each group to determine the best combined stimulatory conditions. Under the optimal costimulatory condition, the activity of caspase-3 was detected by flow cytometry, annexin V-FITC/PI double staining combined with flow cytometry was used to detect the apoptosis, Western blotting was performed to test the level of phosphorylated signal transducer and activator of transcription 3 (pSTAT3) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2). Results The cell activity was the lowest in 24-hour hypoxia group and 100 ng/mL TNF-α group. Therefore, we confirmed the combination of hypoxia for 24 hours and 100 ng/mL TNF-α as the costimulatory conditions. The caspase-3 activity and apoptosis rate in the combined treatment group were higher, compared with the other groups. The expression of pSTAT3, rather than pERK1/2, increased in the combined treatment group, compared with the control group. Moreover, the STAT3 inhibitor S3I-201 reduced the apoptosis rate in the combined treatment group. Conclusion Combined hypoxia and TNF-α could promote HPMVEC apoptosis by activating STAT3 rather than ERK1/2.

Inhibition of STAT3 activity delays obesity-induced thyroid carcinogenesis in a mouse model

Compelling epidemiologic studies indicate that obesity is a risk factor for many human cancers, including thyroid cancer. In recent decades, the incidence of thyroid cancer has dramatically increased along with a marked rise in obesity prevalence. We previously demonstrated that a high fat diet (HFD) effectively induced the obese phenotype in a mouse model of thyroid cancer (Thrb(PV/PV)Pten(+/-) mice). Moreover, HFD activates the STAT3 signal pathway to promote more aggressive tumor phenotypes. The aim of the present study was to evaluate the effect of S3I-201, a specific inhibitor of STAT3 activity, on HFD-induced aggressive cancer progression in the mouse model of thyroid cancer. WT and Thrb(PV/PV)Pten(+/-) mice were treated with HFD together with S3I-201 or vehicle-only as controls. We assessed the effects of S3I-201 on HFD-induced thyroid cancer progression, the leptin-JAK2-STAT3 signaling pathway, and key regulators of epithelial-mesenchymal transition (EMT). S3I-201 effectively inhibited HFD-induced aberrant activation of STAT3 and its downstream targets to markedly inhibit thyroid tumor growth and to prolong survival. Decreased protein levels of cyclins D1 and B1, cyclin dependent kinase 4 (CDK4), CDK6, and phosphorylated retinoblastoma protein led to the inhibition of tumor cell proliferation in S3I-201-treated Thrb(PV/PV)Pten(+/-) mice. Reduced occurrence of vascular invasion and blocking of anaplasia and lung metastasis in thyroid tumors of S3I-201-treated Thrb(PV/PV)Pten(+/-) mice were mediated via decreased expression of vimentin and matrix metalloproteinases, two key effectors of EMT. The present findings suggest that inhibition of the STAT3 activity would be a novel treatment strategy for obesity-induced thyroid cancer.

[STAT signaling pathway mediates high glucose induced cardiac fibroblasts proliferation and collagen deposition in vitro]

OBJECTIVE

To observe the signal transducers and activator of transcriptions (STATs) protein expression changes and investigate the functional role of STATs pathway in case of high glucose-induced cardiac fibroblasts (CFs) proliferation and collagen deposition in vitro.

METHODS

Rat cardiac fibroblasts were isolated from 1- to 3-day-old SD rats, cells from the second to fourth passages were used for the experiment. CFs were cultured in Dulbecco's modified Eagle's medium, supplemented with 5.5 mmol/L glucose (NG), 5.5 mmol/L glucose plus 19.4 mmol/L mannose (OC) or 25 mmol/L glucose (HG) in the presence of absence of STAT1 inhibitor (fludarabine, FLU) and STAT3 inhibitor (S3I-201). After 24 h and 48 h culture in vitro, the proliferation of CFs was measured by 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. After 12 h and 24 h culture in vitro, the production of type I and III collagen was evaluated using real-time quantitative PCR and ELISA. After 0, 30, 60 and 120 min culture in vitro, the phosphorylated expression of STAT1 and STAT3 was analyzed by Western blot.

RESULTS

CFs proliferation was significantly enhanced post 24 h and 48 h HG stimulation, and procollagen I and III mRNA expression was significantly upregulated post 12 h and 24 h HG stimulation. Deposition of collagen I and III was also significantly increased post 24 h and 72 h HG stimulation. STAT1 phosphorylation in CFs was increased after 120 min HG stimulation and STAT3 phosphorylation in CFs was increased post 60 min and 120 min HG stimulation. FLU and S3I-201 could inhibit HG-induced CFs proliferation and suppress of which was stimulated by FLU and S3I-201 could both suppress upregulated procollagen I and III mRNA expression and the deposition of collagen types I and III post HG stimulation. STAT1 phosphorylation inhibition resulted in less mRNA downregulation of procollagen type III than that of procollagen type I post 12 h HG stimulation. The STAT3 phosphorylation inhibition resulted in more significantly upregulated procollagen type III mRNA expression than procollagen type I mRNA expression at 12 h post HG stimulation.

CONCLUSION

HG could enhance the protein expression of phosphorylated STAT1 and STAT3 in CFs, which are responsible for HG-induced increased CFs proliferation and collagen deposition in vitro.

STAT3 upregulation in pituitary somatotroph adenomas induces growth hormone hypersecretion

Pituitary somatotroph adenomas result in dysregulated growth hormone (GH) hypersecretion and acromegaly; however, regulatory mechanisms that promote GH hypersecretion remain elusive. Here, we provide evidence that STAT3 directly induces somatotroph tumor cell GH. Evaluation of pituitary tumors revealed that STAT3 expression was enhanced in human GH-secreting adenomas compared with that in nonsecreting pituitary tumors. Moreover, STAT3 and GH expression were concordant in a somatotroph adenoma tissue array. Promoter and expression analysis in a GH-secreting rat cell line (GH3) revealed that STAT3 specifically binds the Gh promoter and induces transcription. Stable expression of STAT3 in GH3 cells induced expression of endogenous GH, and expression of a constitutively active STAT3 further enhanced GH production. Conversely, expression of dominant-negative STAT3 abrogated GH expression. In primary human somatotroph adenoma-derived cell cultures, STAT3 suppression with the specific inhibitor S3I-201 attenuated GH transcription and reduced GH secretion in the majority of derivative cultures. In addition, S3I-201 attenuated somatotroph tumor growth and GH secretion in a rat xenograft model. GH induced STAT3 phosphorylation and nuclear translocation, indicating a positive feedback loop between STAT3 and GH in somatotroph tumor cells. Together, these results indicate that adenoma GH hypersecretion is the result of STAT3-dependent GH induction, which in turn promotes STAT3 expression, and suggest STAT3 as a potential therapeutic target for pituitary somatotroph adenomas.

Impact of STAT3 inhibition on survival of osteosarcoma cell lines

BACKGROUND/AIM

Osteosarcoma is often a fatal malignancy. Constitutive STAT3 activation is associated with various human cancers and commonly suggests poor prognosis. We aimed to investigate the effect and potential molecular mechanisms of STAT3 inhibition on osteosarcoma.

MATERIALS AND METHODS

STAT3 inhibitor S3I-201 was investigated in six osteosarcoma cell lines. Crystal violet colorimetric, clonogenic, cleaved caspase-3 assays and western blot were performed to measure the effect and mechanisms of STAT3 inhibition.

RESULTS

All osteosarcoma cell lines expressed phosphorylated STAT3. Anti-proliferative effects of S3I-201 were dose- and time-dependent. S3I-201 also inhibited colony-formation and induced apoptosis through the caspase cleavage pathway. Finally, molecular mechanism studies suggested that down-regulation of STAT3 phosphorylation and downstream STAT3-target genes such as cyclin D1 and survivin may contribute to S3I-201-mediated anti-proliferation and apoptosis.

CONCLUSION

Inhibition of STAT3 signalling suppressed osteosarcoma cell growth and induced apoptosis, and indicated that STAT3 targeted-therapy may have therapeutic potential in osteosarcoma.

Function of shrimp STAT during WSSV infection

JAK/STAT signaling pathway plays key roles in the antiviral immunity of mammals, fish and insect. However, limited knowledge is known about the function of JAK/STAT signaling pathway in the antiviral immunity of shrimp although virus disease has caused severe mortality in shrimp aquaculture. In order to understand the function of JAK/STAT signaling pathway in the antiviral immunity of shrimp, dsRNA interfering technique was used to silence the expression of STAT gene in Litopenaeus vannamei, and the mortality of shrimp was detected after WSSV infection. Furthermore, the expressions of some potential target genes regulated by STAT or genes related to RNA interfering pathway were detected in STAT silenced shrimp during WSSV infection. The WSSV copy number in STAT silenced shrimp was 10(2)-10(3) copies/ng DNA which was much lower than that in the control. The mortality in STAT silenced shrimp caused by WSSV infection decreased very significantly compared to their controls. The function of STAT was verified in vitro cultured cells of hematopoietic tissue of crayfish Cherax quadricarinatus by adding specific inhibitor of STAT3(S3I-201), and the cultured cells treated with S3I-201 showed much less WSSV copy number than their controls, which further suggested that STAT might be helpful for the replication of WSSV. Expression analysis on the potential STAT target genes and genes in RNA interfering pathway provide important information for understanding the functional mechanism of STAT in antiviral immunity of shrimp.

Hepatitis delta virus induces specific DNA methylation processes in Huh-7 liver cancer cells

Hepatitis delta virus (HDV) is a small, defective RNA virus that can infect only individuals carrying hepatitis B virus. HBV/HDV co-infection results in more severe liver disease than HBV single infection and more rapid progression to cirrhosis and hepatocellular carcinoma (HCC). The epigenetic events involved in hepatocyte transformation towards malignancy in this context are poorly known. Here we report that, in Huh-7 cells, HDV induces DNMT3b expression and is associated to E2F1 transcription factor hypermethylation. Moreover our cell cycle analysis showed that HDV induces G2/M arrest. These findings suggest that HDV could play a role in HCC development at least in part by altering DNA methylation events. A better understanding of the molecular mechanisms involved in HDV-related carcinogenesis could help to identify new therapeutic targets.

APE1/Ref-1 regulates STAT3 transcriptional activity and APE1/Ref-1-STAT3 dual-targeting effectively inhibits pancreatic cancer cell survival

Pancreatic cancer is a largely incurable disease, and increasing evidence supports strategies targeting multiple molecular mediators of critical functions of pancreatic ductal adenocarcinoma cells. Intracellular redox state modulates the activity of various signal transduction pathways and biological processes, including cell survival, drug resistance and responsiveness to microenvironmental factors. Recently, it has been shown that the transcription factor STAT3 is under redox control, but the mechanisms involved in its regulation are unknown. Here, we demonstrate for the first time that STAT3 DNA binding and transcriptional activity is directly regulated by the redox function of the APE1/Ref-1 endonuclease, using overexpression and redox-specific mutational strategies, and gene knockdown. Also, pharmacological blockade of APE1/Ref-1 by the redox-selective inhibitor E3330 abrogates STAT3 DNA binding. Since APE1/Ref-1 also exerts redox control on other cancer-associated transcription factors, we assessed the impact of dual-targeting of STAT3 signaling and APE1/Ref-1 redox on pancreatic cancer cell functions. We observed that disruption of APE1/Ref-1 redox activity synergizes with STAT3 blockade to potently inhibit the proliferation and viability of human PDAC cells. Mechanistically, we show that STAT3–APE1/Ref-1 dual targeting promotes marked tumor cell apoptosis, with engagement of caspase-3 signaling, which are significantly increased in comparison to the effects triggered by single target blockade. Also, we show that STAT3–APE1/Ref-1 dual blockade results in significant inhibition of tumor cell migration. Overall, this work demonstrates that the transcriptional activity of STAT3 is directly regulated by the redox function of APE1/Ref-1, and that concurrent blockade of STAT3 and APE1/Ref-1 redox synergize effectively inhibit critical PDAC cell functions.

PAF formation by human gastrointestinal mucosa/submucosa in-vitro: release by ricinoleic acid, and inhibition by 5-aminosalicylic acid

Human isolated gastrointestinal mucosa/submucosa incubated with ricinoleic acid (12·5–100 μg mL−1) or the calcium ionophore A23187 (10 μg mL−1) released platelet-activating factor (PAF) as determined by a scintillation proximity assay after extraction and purification. 5-Aminosalicylic acid (25–100 μg mL−1) inhibited PAF release by ricinoleic acid in a concentration-dependent manner, and 50 μg mL−1 reduced the effect of A23187. We suggest that PAF may play a role in the taxation and mucosal damage by ricinoleic acid released from castor oil.

[Identification of a repetitive sequence element for DNA fingerprinting in Phytophthora sojae]

OBJECTIVE

Establishment of DNA fingerprinting in Phytophthora sojae and an analysis of genetic relationship of Heilongjiang and Xinjiang populations.

METHODS

Bioinformatics tools were used to search repetitive sequences in P. sojae and Southern blot analysis was employed for DNA fingerprinting analysis of P. sojae populations from Heilongjiang and Xinjiang using the identified repetitive sequence.

RESULTS

A moderately repetitive sequence was identified and designated as PS1227. Southern blot analysis indicated 34 distinct bands ranging in size from 1.5 kb-23 kb, of which 21 were polymorphic among 49 isolates examined. Analysis of single-zoospore progenies showed that the PS1227 fingerprint pattern was mitotically stable. DNA fingerprinting showed that the P. sojae isolates HP4002, SY6 and GJ0105 of Heilongjiang are genetically identical to DW303, 71228 and 71222 of Xinjiang, respectively.

CONCLUSION

A moderately repetitive sequence designated PS1227 which will be useful for epidemiology and population biology studies of P. sojae was obtained, and a PS1227-based DNA fingerprinting analysis provided molecular evidence that P. sojae in Xinjiang was likely introduced from Heilongjiang.

The effect of sulfasalazine and its active components on human polymorphonuclear leukocyte function in relation to ulcerative colitis

Sulfasalazine and its active components, 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP), are potent modulators of inflammatory reactions but with somewhat different modes of action. Investigating the effect of these compounds on normal human polymorphonuclear leukocytes in vitro, we show inhibition of different stages in the phagocytic process, such as migration (sulfasalazine and SP), superoxide production (sulfasalazine and SP), myeloperoxidase-mediated iodination and cytotoxicity (5-ASA and SP). It is thus suggested that sulfasalazine is not just a vehicle for delivering its active components in the colon, but that its therapeutic effect is ulcerative colitis and other inflammatory reactions is a result of the concurrent action of the three compounds.

Aminosalicylates and other anti-inflammatory compounds for irritable bowel syndrome

Growing evidence suggests that gastrointestinal immune activation may affect intestinal function and sensory perception, which contribute to symptom generation in patients with irritable bowel syndrome (IBS). The identification of higher counts of immunocytes (e.g. T cells and mast cells), mucosal and systemic immune activation, and increased mucosal permeability in patients with IBS has stimulated interest in the potential development of therapeutic approaches aimed at targeting the immune system and inflammation. Although an initial attempt in a pilot trial with steroids in patients with post-infective IBS failed, there has been renewed interest for mast cell stabilizers and the therapeutic potential of aminosalicylates. A recent randomized, double-blind, placebo-controlled pilot trial assessed the effect of mesalazine on intestinal immune cells and symptom perception in patients with IBS. Mesalazine markedly reduced mucosal immune cells and mast cells in particular, compared to placebo. In addition, mesalazine significantly improved general well-being. Mesalazine may enhance epithelial barrier function, and preliminary data suggest that it may alter faecal bacterial profiles in IBS patients. Nevertheless, the exact mechanism through which this drug affects immune activation in the intestine of patients with IBS remains unknown. There is a need for further studies to prove the efficacy of mesalazine for IBS. Further studies aimed at assessing the role of aminosalicylates and other approaches with potential anti-inflammatory activity, including probiotics, non-absorbable antibiotics, histamine receptor antagonists and protease inhibitors on IBS symptoms or pathophysiology are now warranted.

5-amino salicylic acid bound nanoparticles for the therapy of inflammatory bowel disease

Nanoparticles (NP) are known for their specific accumulation in the inflamed tissues in the colon and may therefore allow a selective delivery to the site of inflammation including a reduction of adverse effects. 5-amino salicylic acid (5ASA) loaded NP were designed in order to investigate their therapeutic potential in the treatment of inflammatory bowel disease. 5ASA was covalently bound to poly(caprolactone) prior to all formulation steps. Oil/water emulsification or nanoprecipitation methods were used for the NP formulation. Particle diameters were either 200 or 350 nm for emulsification or nanoprecipitation, respectively. In-vitro drug release demonstrated a significant drug retention inside the NP formulation. Toxicity of the different formulations was evaluated on Caco-2 and HEK cell culture which was slightly increased for 5ASA grafted NP in comparison to blank NP (Me5ASA-NP: 75 microg/l; blank NP: 210 microg/l). In-vivo, clinical activity score and myeloperoxidase activity decreased after administration of all 5ASA containing formulations (untreated control: 28.0+/-5.6 U/mg; 5ASA-NP (0.5 mg/kg): 15.2+/-5.6 U/mg; 5ASA solution (30 mg/kg): 16.2+/-3.6 U/mg). NP formulations allowed to lower significantly the dose of 5ASA. These oral NP formulations demonstrated their therapeutic potential and appear to be an interesting approach for the therapy of inflammatory bowel disease.

RETRACTED: Synthesis, kinetic studies and pharmacological evaluation of mutual azo prodrug of 5-aminosalicylic acid for colon-specific drug delivery in inflammatory bowel disease

Mutual azo prodrug of 5-aminosalicylic acid with l-tyrosine was synthesized by coupling l-tyrosine with salicylic acid, for targeted drug delivery to the inflamed gut tissue in inflammatory bowel disease. The structure was confirmed by elemental analysis, IR and NMR spectroscopy. In vitro kinetic studies in rat fecal matter showed 87.18% release of 5-aminosalicylic acid with a half-life of 140.28min, following first order kinetics. Therapeutic efficacy of the carrier system and the mitigating effect of the azo conjugate were evaluated in trinitrobenzenesulfonic acid-induced experimental colitis model. Myeloperoxidase activity was determined by the method of Krawisz et al. The synthesized prodrug was found to produce comparable mitigating effect as that of sulfasalazine on colitis in rats.

Drug insight: aminosalicylates for the treatment of IBD

Sulfasalazine and mesalazine (also known as mesalamine; 5-aminosalicylic acid) preparations have for many years been used for the treatment of IBD (i.e. ulcerative colitis and Crohn's disease), for both active disease and the control of remission. It has also been suggested that mesalazine is a chemoprophylactic agent that protects against the development of colorectal cancer. This Review focuses on the latest clinical evidence for the use of these aminosalicylates for the treatment of IBD, and concludes that sulfasalazine and mesalazine are useful for the treatment of both active and quiescent ulcerative colitis, whereas they have no clinical effect on either active or inactive Crohn's disease. Furthermore, evidence is lacking that mesalazine per se is a chemoprophylactic agent.

Different sensitivity of lamina propria T-cell subsets to nitric oxide-induced apoptosis explains immunomodulatory activity of a nitric oxide-releasing derivative of mesalamine in rodent colitis

BACKGROUND & AIMS

Uncontrolled T-cell activation plays a critical role in the pathogenesis of inflammatory bowel diseases. Therefore, pharmacological strategies directed toward restoring the normal responsiveness of the immune system could be effective in the treatment of these pathologic conditions. The addition of a nitric oxide-releasing moiety to conventional drugs, such as aspirin and other anti-inflammatory analgesic drugs, results in new chemical entities with potent immunomodulatory activities. The aim of this study was to investigate the immunomodulatory activity of a nitric oxide-releasing derivative of mesalamine (NCX-456), as compared with standard mesalamine, in 2,4,6-trinitrobenzene sulfonic acid-induced colitis in mice.

METHODS

Cells and tissues from mice with 2,4,6-trinitrobenzene sulfonic acid-induced colitis and from interleukin 10-deficient mice with spontaneous chronic colitis receiving treatment with several doses of NCX-456 or mesalamine were analyzed for morphology, cytokine production, and apoptosis.

RESULTS

NCX-456, but not mesalamine, administration resulted in a marked reduction in clinical, histological, and immunologic signs of colitis in both models. NCX-456 inhibited the release of T-helper type 1-derived cytokines and increased the release of the regulatory T cell-derived cytokines interleukin 10 and transforming growth factor beta. In vitro analyses showed that NCX-456 inhibited proliferation and caused selective apoptosis of the subset of activated lamina propria T-helper type 1 cells, whereas it was ineffective for regulatory T-cell function and survival.

CONCLUSIONS

Collectively, these data show that NCX-456 inhibits lamina propria T-helper type 1 function and stimulates the activity of interleukin 10- and transforming growth factor beta-secreting cells, thus restoring mucosal immune homeostasis and suppressing intestinal inflammation.

Comparative analysis of the in vitro prosecretory effects of balsalazide, sulfasalazine, olsalazine, and mesalamine in rabbit distal ileum

BACKGROUND

The aminosalicylates remain foundation therapy for mild-to-moderate ulcerative colitis. Pro-drug 5-aminosalicylic acid (5-ASA; mesalamine) formulations have been developed to prevent 5-ASA from the proximal absorption and release of mesalamine, to decrease inflammation, and to improve colonic absorption. Clinically, pro-drugs such as olsalazine have been associated with dose-dependent diarrhea, which was likely secondary to ileal secretion induced by the azo linkages, in 17% of patients. The present study tested the hypothesis that the use of all compounds with azo linkages leads to increased secretion.

METHODS

Intestinal tissue was randomly assigned to serve as controls or to receive brush border addition of equimolar concentrations of the compounds, and the change in short-circuit current was measured.

RESULTS

Mesalamine did not induce secretion at any dose. Mean equivalent doses (0.1 to 10 mM) of balsalazide (range, 6.3 +/- 1.5 to 16.7 +/- 1.3 microA/cm2), olsalazine (range, 2.0 +/- 1.0 to 7.0 +/- 2.1 microA/cm2), and sulfasalazine (3.2 +/- 1.1 to 6.2 +/- 1.5 microA/cm2) significantly stimulated (P < 0.001) secretion. The values for the effective dose that is half the maximal dose for secretion induced by sulfasalazine, olsalazine, and balsalazide were 0.4, 0.7, and 0.9 mM, respectively.

CONCLUSIONS

This study is the first to demonstrate that the use of pro-drugs with azo bonds leads to increased ileal secretion at equimolar concentrations of 5-ASA. Physicians should use caution when providing higher doses of the pro-drug forms of 5-ASA to their patients, as this could lead to increased diarrhea.

Ulcerative colitis therapy: importance of delivery mechanisms

Since the initial observation that mesalamine or 5-aminosalicylate (5-ASA) has an anti-inflammatory effect on ulcerative colitis, investigators have been trying to improve on the delivery mechanisms of this compound. As it is believed that the anti-inflammatory effect of 5-ASAs is mediated topically, current formulations are designed to release 5-ASA in the small intestine and colon, or predominantly in the colon. A dose-response curve is seen with some preparations of mesalamine but not all. In general, 5-ASAs are effective in patients with ulcerative colitis and much less effective in Crohn's disease. Evidence demonstrates that 5-ASAs are effective for induction of remission and maintenance of remission. Preparations that deliver 5-ASA in a pH-dependent manner are most affected by variability in luminal pH, whereas those that depend on bacterial cleavage for release of the active 5-ASA are most affected by transit time. Most studies have not compared different preparations of mesalamine and examined differences in colonic delivery. Depending on the endpoint examined in the studies, efficacy of the various 5-ASA products appears similar at the most optimal doses. For a given patient, however, it may be necessary to experiment with more than one preparation if an initial trial results in a suboptimal response.

Effect of 5-substituted benzylideneaminosalicylic acid on carrageenan-induced ulcerative colitis

Mesalazine, a drug of choice in the management of ulcerative colitis, was chemically modified as 5-(E)-substituted benzylideneaminosalicylic acid by condensing 5-aminosalicylic acid with selected aryl aldehydes with an intention to improve its pharmacological profile. The tests were performed to study their anti-inflammatory effect on carrageenan-induced ulcerative colitis in albino rats. The histopathological findings, serum transaminase level and lipid peroxide content in the intestine and liver were taken as indices of pharmacological activity. The azomethine derivative formed from salicylaldehyde (5-ASASB3) was found to have maximum activity and it reversed the disease symptoms in experimental animals The azomethine derivative markedly reduces the ulcerative colitis when compared with parent molecule, mesalazine.

Review article: aminosalicylates in inflammatory bowel disease

Aminosalicylate therapy for ulcerative colitis remains a foundational strategy for the induction and maintenance of remission for mild to moderate disease. Although it seems clear that topical mesalazine (mesalamine) is the most efficacious approach to distal ulcerative colitis, recent trials with orally delivered azo conjugates suggest that there may be an advantage over pH-released mesalazine as a first-line approach to active disease. No such comparisons are available for azo products and the prolonged-release formulation, Pentasa. However, recent meta-analyses have demonstrated that, although there is little difference in systemic exposure between marketed products, luminal concentrations may vary. In maintenance therapy, aminosalicylates remain the standard approach after aminosalicylate-induced remission. A number of gaps remain in the evidence base with regard to the optimal dosing of oral mesalazine as a maintenance agent, whether oral mesalazine can maintain remissions after rectal mesalazine induction, and the dose-response and efficacy of aminosalicylates after steroid- or ciclosporin-induced remissions. Although aminosalicylates have been advocated for several decades in Crohn's disease, a number of controversies have evolved since the original trials with sulfasalazine in active Crohn's disease. The original trials demonstrated benefits for sulfasalazine in colonic involvement, but controlled trial evidence for the role of sulfasalazine as maintenance therapy has not been as firmly established. In addition, although oral mesalazine has been demonstrated in controlled trials to be superior to placebo in mild to moderate disease, it is less efficacious than corticosteroids at inducing remissions. The maintenance benefits of mesalazine appear to be limited to patients 'induced into remission' with mesalazine and in some post-operative settings.

A novel anti-oxidant and anti-cancer strategy: a peptoid anti-inflammatory drug conjugate with SOD mimic activity

Activation of reactive oxygen and nitrogen species (RONS) by redox-active metal ions has been proposed to contribute to oxidative damage in inflamed tissues. Here, we report a dual-function anti-oxidant conjugate comprising an anti-inflammatory agent (5-aminosalicylic acid) and a chelator with potential as a superoxide dismutase mimic. The conjugate ethylenediaminetetraacetic acid bis-(5-aminosalicylic acid methyl ester) [EBAME] chelates Cu(II) ions in a 1:1 ratio, as assessed spectrophotometrically using Job's method. Superoxide dismutase (SOD) activity was determined for the Mn(II)-conjugate as 0.758+/-0.130 U at a concentration of 0.99 microM. In inflamed tissues, peptidase mediated release of active 5-ASA would also release the EDTA chelator which has significant SOD mimic activity when complexed to Cu(II) ions. Thus, EBAME has potential as a dual-function anti-inflammatory agent with reduced gastric irritability.

The short- and long-term safety of 5-aminosalicylate products in the treatment of ulcerative colitis

5-aminosalicylic acid agents are effective in the treatment of ulcerative colitis. Balsalazide, mesalamine, and olsalazine are alternative formulations to sulfasalazine for the delivery of 5-aminosalicylic acid. The newer compounds might be better tolerated than sulfasalazine in some patients, as long as the intolerance is not due to hypersensitivity to 5-aminosalicylic acid. Adverse events requiring the withdrawal of therapy seem to occur less frequently with balsalazide, mesalamine, and olsalazine compared with sulfasalazine. If patients are unable to tolerate any one of these three 5-aminosalicylic acid-releasing preparations, they might be able to tolerate one of the others, as long as the intolerance is not due to hypersensitivity to 5-aminosalicylic acid.

Nitric oxide-releasing mesalamine: potential utility for treatment of inflammatory bowel disease

Nitric oxide can accelerate ulcer healing and exert anti-inflammatory effects. Addition of a nitric oxide-releasing moiety to mesalamine significantly boosts its anti-inflammatory activity. NO-releasing mesalamine suppresses inflammatory cytokine production and reduces leukocyte infiltration.

Impact on the bowel of amtolmetin guacyl, a new gastroprotective non-steroidal anti-inflammatory drug

Amtolmetin guacyl (MED15) is a new non-steroidal anti-inflammatory drug (NSAID) which shares anti-inflammatory, analgesic and antipyretic activity with the other drugs of the NSAID family but which shows, unexpectedly, strong gastroprotective activity similar to misoprostol. This effect has been attributed to the presence in its molecule of a vanillic moiety responsible for stimulation of capsaicin receptors present throughout the length of the gastrointestinal tract. MED15 shows antispasmodic activity in the bowel against a number of agonists and compares favourably with reference compounds. In in vivo indomethacin-induced rat ileitis, MED15 heals better than 5-aminosalicylic acid and sulfasalazine, as well as down-regulating intestinal wall myeloperoxidase content. In acetic acid-induced colitis in the rat, levels of malondialdehyde were found to be more markedly reduced with MED15 than with 5-aminosalicylic acid. In contrast with the effect in the stomach, MED15 protective effect in the bowel appears to be unrelated to nitric oxide (NO) production. The MED15 enteroprotective effect is related to stimulation of intestinal capsaicin receptors as demonstrated by the loss of protective effect in the presence of capsazepine, a specific receptor antagonist of capsaicin. In conclusion, following the favourable results obtained in animal models and notwithstanding the pharmacological effects typical of an NSAID, MED15 may rationally be proposed for the treatment of various human colitis conditions and Crohn's disease.

Aminosalicylic acid reduces the antiproliferative effect of hyperglycaemia, advanced glycation endproducts and glycated basic fibroblast growth factor in cultured bovine aortic endothelial cells: comparison with aminoguanidine

Hyperglycaemia reduces proliferation of bovine aortic endothelial cells in vitro. A similar effect in vivo may contribute to long-term complications of diabetes such as impaired wound-healing and retinopathy. We report the effect of increased glucose concentrations, glycated basic fibroblast growth factor (FGF-2) and bovine serum albumin-derived advanced glycation endproducts (BSA-AGE) on the proliferation of bovine aortic endothelial cells. Glucose (30 and 50 mmol/l) had an antiproliferative effect on endothelial cells. This effect may be mediated through reduced mitogenic activity of FGF-2. The glycation of FGF-2 with 250 mmol/l glucose-6-phosphate led to reduced mitogenic activity compared to native FGF-2. BSA-AGE at concentrations of 10, 50 and 250 microg/ml had an antiproliferative effect on cultured endothelial cells. Aminosalicylic acid at a concentration of 200 micromol/l proved to be more effective than equimolar concentrations of aminoguanidine in protecting endothelial cells against the antiproliferative effects of both high (30 mmol/l) glucose and 50 microg/ml BSA-AGE. FGF-2 glycated in the presence of 4 mmol/l aminosalicylic acid or aminoguanidine retained mitogenic activity compared to that glycated in their absence. Compounds like aminoguanidine and, in particular, aminosalicylic acid protect endothelial cells against glucose-mediated toxicity and may therefore have therapeutic potential.

The effect of 5-aminosalicylic acid-containing drugs on sulfide production by sulfate-reducing and amino acid-fermenting bacteria

The toxic, bacterial metabolite sulfide is implicated in ulcerative colitis. Ulcerative colitis patients taking 5-aminosalicylic acid-containing drugs have lower fecal sulfide levels than those not taking these drugs. The effects of sulfasalazine, balsalazide, olsalazine, and 5-aminosalicylic acid on sulfide production were studied in a three-stage chemostat pulsed on days 1 to 3 with 5 g sulfasalazine (40 mM) and in pure cultures of amino acid-fermenting and sulfate-reducing bacteria. By the third day of sulfasalazine addition to the chemostat, sulfide concentrations in vessels 1 through 3 had dropped from 1.73, 1.78, and 1.43 mM to 0.01, 0.15, and 0.9 mM, respectively. In pure cultures, 50% inhibition of sulfide production from amino acids occurred at 2.5 +/- 0.05 mM for sulfasalazine, 5 +/- 0.2 mM for olsalazine, 6 +/- 1 mM for balsalazide, and more than 20 mM for 5-aminosalicylic acid. Fifty percent inhibition of sulfide production from sulfate occurred at 0.25 +/- 0.05 mM for sulfasalazine, 0.7 +/- 0.2 mM for balsalazide, and 9.0 +/- 1.0 mM for 5-aminosalicylic acid. The order of effectiveness of equimolar concentrations of drugs (most effective first) in this assay was sulfasalazine, then olsalazine (though given clinically at half the dose of other 5-aminosalicylic acid prodrugs) and balsalazide, and lastly 5-aminosalicylic acid. Inhibition of sulfide production by 5-aminosalicylic acid-containing drugs may contribute to their therapeutic effect in ulcerative colitis.

A double-blind comparison of balsalazide, 6.75 g daily, and sulfasalazine, 3 g daily, in patients with newly diagnosed or relapsed active ulcerative colitis

BACKGROUND

Sulfasalazine is well established in the treatment of active ulcerative colitis. Intolerance to sulfasalazine, however, is a common problem. Balsalazide has been designed to deliver 5-aminosalicylic acid to the colon without the poor tolerability of sulfasalazine.

AIM

To compare the safety and efficacy of balsalazide, 6.75 g daily, with sulfasalazine, 3 g daily, in the treatment of active ulcerative colitis of all grades of severity.

METHODS

Balsalazide and sulfasalazine were compared in a multicentre, double-blind, parallel group study over 12 weeks. Patients were stratified for disease severity and topical and/or oral steroids were co-administered where clinically necessary.

RESULTS

Fifty-seven patients were randomized: 28 to receive balsalazide and 29 to receive sulfasalazine. Significantly fewer patients withdrew from the balsalazide group due to adverse events (2/28 vs. 9/29, P=0.041). These data confirm that balsalazide is better tolerated than sulfasalazine. In patients able to tolerate the treatment, similar improvements were recorded in clinical, sigmoidoscopic and histological assessments in both treatment groups.

CONCLUSIONS

This study confirms the better tolerability of balsalazide compared to sulfasalazine, and supports the use of balsalazide in ulcerative colitis of all grades of severity.

A double-blind comparison of balsalazide, 6.75 g, and sulfasalazine, 3 g, as sole therapy in the management of ulcerative colitis

BACKGROUND

Sulfasalazine is accepted therapy for active ulcerative colitis, but side-effects and intolerance are common. Balsalazide is an azo-bonded pro-drug which also releases 5-aminosalicylic acid into the colon, but uses an inert carrier molecule.

AIM

To compare the safety and efficacy of sul- fasalazine, 3 g, with balsalazide, 6.75 g, in the initial daily treatment of mild to moderate ulcerative colitis.

METHODS

A randomized, multicentre, double-blind, parallel group study was performed, with a treatment duration of 8 weeks. Patients on previous maintenance treatment were excluded. The trial medication was the sole treatment for the colitis. Efficacy was assessed by patient diaries, symptom assessment, sigmoidoscopic appearance and histology.

RESULTS

Fifty patients were recruited: 26 allocated to the balsalazide group and 24 to the sulfasalazine group. More patients withdrew due to adverse events in the sulfasalazine group (nine patients vs. one patient in the balsalazide group, P=0.004). Improvement occurred in both groups, with a tendency to a faster response with balsalazide. Of the patients taking balsalazide, 61% achieved clinical and sigmoidoscopic remission.

CONCLUSIONS

Balsalazide, 6.75 g, is effective as the sole treatment for patients with mild to moderately active ulcerative colitis, with significantly fewer withdrawals due to side-effects than in a similar group of patients taking sulfasalazine, 3 g.

NO-mesalamine protects colonic epithelial cells against apoptotic damage induced by proinflammatory cytokines

The activation of a self-amplifying cascade of caspases, of which caspase-8 is the apical protease, mediates Fas-, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-, and TNF-alpha-induced apoptosis in colon cell lines. Nitric oxide (NO) protects from apoptosis induced by Fas and TNF-alpha. We examined whether NCX-456, an NO-releasing derivative of mesalamine, protects colon epithelial cells from cytokine-induced apoptosis. Caco-2 and HT-29 cell lines express death factor receptors and are driven to apoptosis in response to incubation with Fas-agonistic antibody, TNF-alpha/interferon-gamma, and TRAIL. The two novel observations reported here are that 1) cotreatment of cells with NCX-456, but not mesalamine, resulted in concentration-dependent protection against death factor-induced apoptosis and inhibition of caspase activity, and 2) exposure to dithiothreitol, an agent that effectively removes NO from thiol groups, resulted in a 70% recovery of caspase activity, which is consistent with S-nitrosation as a major mechanism for caspase inactivation. These data suggest that caspase S-nitrosation represents a mechanism for protection of colonic mucosal epithelial cells from death factor-induced death.

Topical acetyl salicylate and dipyrone attenuate neurogenic protein extravasation in rat skin in vivo

The effect of topically applied acetyl salicylic acid (ASA) and dipyrone on capsaicin-evoked protein extravasation was investigated by dermal microdialysis in rat. After a baseline of 75 min, capsaicin (1%) was applied epicutaneously under occlusion for 75 min above the capillaries. Topical capsaicin stimulation induced neurogenic protein extravasation with a mean increase of protein concentration in the perfusate of 165+/-27% (mean+/-SEM; n=15), whereas in sham-stimulated sites protein concentration decreased to 73+/-7% of the prestimulation value (n=6). ASA (2-200 mg/ml) and dipyrone (3-300 mg/ml) dose-dependently reduced the capsaicin induced protein extravasation to 118+/-23% (ASA, 200 mg/ml; n=8) and 72+/-9% (dipyrone, 300 mg/ml; n=8) of the prestimulation value. ASA and dipyrone antagonized the excitatory effects of capsaicin on skin nociceptors and thus suppressed the neurogenic protein extravasation.

5-aminosalicyclic acid and olsalazine inhibit tumor growth in a rodent model of colorectal cancer

The ability of 5-aminosalicylic acid and olsalazine to inhibit colonic aberrant crypts and tumors was investigated in 1,2-dimethylhydrazine-treated rats. The effect of these drugs on the rates of tumor apoptosis and proliferation was studied as potential mechanisms for their action. 5-Aminosalicylic acid reduced the number of aberrant crypt foci by over one third, while olsalazine had no effect on this parameter. However, both agents effectively reduced tumor number and load, increased the rate of tumor apoptosis, and reduced the rate of tumor cell proliferation. In conclusion, 5-aminosalicylic acid and olsalazine are both ultimately effective chemopreventive agents in this model; however, only 5-aminosalicylic acid inhibited the formation of aberrant crypt foci. The inhibitory effect of these agents in tumors is related to the inhibition of proliferation and the induction of apoptosis.

Chemoprevention of colon cancer carcinogenesis by balsalazide: inhibition of azoxymethane-induced aberrant crypt formation in the rat colon and intestinal tumor formation in the B6-Min/+ mouse

Non-steroidal anti-inflammatory drugs (NSAIDs) including aspirin have been shown to suppress colon carcinogenesis and in some cases reduce the size of colorectal polyps. Balsalazide disodium (BSZ) is a colon-specific prodrug of the salicylate, 5-aminosalicylic acid. The aim of the present study was to test the chemopreventive activity of BSZ in two established animal models of colon tumorigenesis, azoxymethane-induced aberrant crypt formation in the rat and intestinal tumor formation in the B6-Min/+ mouse. Aberrant crypt foci (ACF) were induced in Fischer 344 rats via 2 subcutaneous injections of azoxymethane (20 mg/kg). BSZ was supplied in the drinking water for 8 weeks and ACF quantitated. B6-Min/+ mice were treated from 55 days of age for 90 days and intestinal tumors scored for number, size and location. BSZ treatment of AOM-injected rats reduced ACF formation in a dose-dependent manner by 60% with the greatest effect observed on ACF with 4 or more crypts. In B6-Min/+ mice a dose-dependent reduction of intestinal tumor number was observed which reached 80% in the distal small intestine and colon. A preliminary mechanistic study in cultured human colon cancer cells showed that both BSZ and 5-ASA inhibited colon cancer cell proliferation in vitro. However, 5-ASA but not BSZ produced changes consistent with the induction of apoptosis. BSZ produces a dose-dependent chemopreventive effect on colon carcinogenesis. A possible mechanism is consistent with the inhibition of cellular proliferation and the induction of apoptosis.