Telmisartan alleviates alcohol-induced liver injury by activation of PPAR-γ/ Nrf-2 crosstalk in mice.

Excessive consumption of alcohol may induce severe liver damage, in part via oxidative stress and inflammatory responses, which implicates these processes as potential therapeutic approaches. Prior literature has shown that Telmisartan (TEL) may provide protective effects, presumably mediated by its anti-oxidant and anti-inflammatory activities. The purpose of this study was to determine TEL's hepatoprotective effects and to identify its possible curative mechanisms in alcoholic liver disease. A mouse chronic alcohol plus binge feedings model was used in the current study for induction of alcoholic liver disease (ALD). Our results showed that TEL (10 mg/kg/day) has the ability to reduce serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). TEL also increased the activity of superoxide dismutase (SOD) and glutathione (GSH) with concomitant reduction of nitric oxide (NO) malonaldehyde (MDA) in the liver homogenate. Moreover, TEL downregulated nuclear factor kappa B (NF-κB) expression and decreased liver content of interleukin-6 (IL-6), interleukin-1ß (IL-1ß), and tumor necrosis factor-α (TNF-α). These anti-inflammatory and anti-oxidant activities were associated with a significant increase in the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), peroxisome proliferator-activated receptors -γ (PPAR-γ), and heme oxygenase-1 (Hmox-1). In conclusion, TEL's hepatoprotective effects against ALD may be attributable to its anti-inflammatory and anti-oxidant activities which may be in part via the modulation of PPAR-γ/ Nrf-2/ NF-κB crosstalk.

Selenium triggers Nrf2-AMPK crosstalk to alleviate cadmium-induced autophagy in rabbit cerebrum.

Cadmium (Cd) is a toxic heavy metal that accumulates in the brain and causes a series of histopathological changes. Selenium (Se) exerts a crucial function in protecting damage caused by toxic heavy metals, but its potential mechanism is rarely studied. The main purpose of this study is to explore the protective effects of Se on Cd-induced oxidative stress and autophagy in rabbit cerebrum. Forty rabbits were randomly divided into four groups and treated as follows: Control group, Cd (1 mg/kg⋅BW) group, Se (0.5 mg/kg⋅BW) group and Cd (1 mg/kg⋅BW)+Se (0.5 mg/kg⋅BW) group, with 30 days feeding management. Our results suggested that Se treatment significantly suppressed the Cd-induced degenerative changes including cell necrosis, vacuolization, and atrophic neurons. In addition, Se decreased the contents of MDA and H2O2 and increased the activities of CAT, SOD, GST, GSH and GSH-Px, alleviating the imbalance of the redox system induced by Cd. Furthermore, Cd caused the up-regulation of the mRNA levels of autophagy-related genes (ATG3, ATG5, ATG7, ATG12 and p62), AMPK (Prkaa1, Prkaa2, Prkab1, Prkab2, Prkag2, Prkag3) and Nrf2 (Nrf2, HO-1 and NQO1) signaling pathway, and the expression levels of LC3II/LC3I, p-AMPK/AMPK, Beclin-1, Nrf2 and HO-1 proteins, which were alleviated by Se, indicated that Se inhibited Cd-induced autophagy and Nrf2 signaling pathway activation. In conclusion, our study found that Se antagonized Cd-induced oxidative stress and autophagy in the brain by generating crosstalk between AMPK and Nrf2 signaling pathway.

Bidirectional Crosstalk Between Hypoxia Inducible Factors and Glucocorticoid Signalling in Health and Disease.

Glucocorticoid-induced (GC) and hypoxia-induced transcriptional responses play an important role in tissue homeostasis and in the regulation of cellular responses to stress and inflammation. Evidence exists that there is an important crosstalk between both GC and hypoxia effects. Hypoxia is a pathophysiological condition to which cells respond quickly in order to prevent metabolic shutdown and death. The hypoxia inducible factors (HIFs) are the master regulators of oxygen homeostasis and are responsible for the ability of cells to cope with low oxygen levels. Maladaptive responses of HIFs contribute to a variety of pathological conditions including acute mountain sickness (AMS), inflammation and neonatal hypoxia-induced brain injury. Synthetic GCs which are analogous to the naturally occurring steroid hormones (cortisol in humans, corticosterone in rodents), have been used for decades as anti-inflammatory drugs for treating pathological conditions which are linked to hypoxia (i.e. asthma, ischemic injury). In this review, we investigate the crosstalk between the glucocorticoid receptor (GR), and HIFs. We discuss possible mechanisms by which GR and HIF influence one another, in vitro and in vivo, and the therapeutic effects of GCs on HIF-mediated diseases.

Orchestrated modulation of rheumatoid arthritis via crosstalking intracellular signaling pathways.

Cell signaling is considered a part of a network for communication that regulates basic cellular activities. The ability of cells to communicate correctly to the surrounding environment has an important role in development, tissue repair, and immunity as well as normal tissue homeostasis. Dysregulated activation and crosstalk between many intracellular signaling pathways are implicated in the pathogenesis of rheumatoid arthritis (RA), such as the Janus Kinase/signal transducers and activators of transcription (JAK/STAT), Toll-like receptor/nuclear factor kappa B (TLR/NF-κB), phosphatidylinositide-3Kinase/protein kinase B/mammalian target of rapamycin (PI-3K/AKT/mTOR), the stress activated protein kinase/mitogen-activated protein kinase (SAPK/MAPK), and spleen tyrosine kinase (SYK) pathways. Other interrelated pathways that can be targeted to halt the inflammatory status in the disease are purinergic 2X7 receptor (P2X7R)/nucleotide binding oligomerization domain-like receptor family pyrin domain containing 3 or inflammasome (NLRP-3)/NF-κB and Notch pathways. In this review, we will show the orchestrated modulation in the pathogenesis of RA via the crossregulation between dysregulated signaling pathways which can mediate a sustained loop of activation for these signaling pathways as well as aggrevate the inflammatory condition. Also, this review will highlight many targets that can be useful in the development of more effective therapeutic options.

Survivin Expression Is Differentially Regulated by a Selective Cross-talk between RBM38 and miRNAs let-7b or miR-203a.

RNA-binding motif 38 (RBM38) is a member of a protein family with a highly conserved RNA-binding motif and has been shown to regulate mRNA processing, stability, and translation. Survivin is an essential modulator of apoptotic and nonapoptotic cell death as well as a stress responder. Survivin mRNA is the fourth most frequently overexpressed transcript in the human cancer transcriptome, and its aberrant expression is associated with chemo-/radioresistance and poor prognosis. In this study, we examined whether survivin expression is regulated by RBM38. RBM38 bound to survivin 3'-untranslated region and suppressed miRNA let-7b from binding to and degrading survivin mRNA, leading to increased survivin expression. RBM38 interacted with argonaute-2 (AGO2) and facilitated miR-203a-mediated degradation of survivin mRNA, leading to decreased survivin expression. Due to the abundance of let-7b over miR-203a, RBM38 ultimately increased survivin expression in HCT116 and MCF7 cells. In addition, Ser-195 in RBM38 interacted with Glu-73/-76 in AGO2, and Pep8, an eight-amino acid peptide spanning the region of Ser-195 in RBM38, blocked the RBM38-AGO2 interaction and inhibited miR-203a-mediated mRNA degradation, leading to enhanced survivin expression. Furthermore, Pep8 cooperated with YM155, an inhibitor of survivin, to suppress tumor spheroid growth and viability. Pep8 sensitized tumor cells to YM155-induced DNA damage in an RBM38-dependent manner. Together, our data indicate that RBM38 is a dual regulator of survivin and that Pep8/YM155 may be therapeutically explored for tumor suppression. SIGNIFICANCE: These findings show that RBM38 exerts opposing effects on survivin expression via two miRNAs, and disruption of the RBM38-AGO2 complex by an eight-amino acid peptide sensitizes tumor spheroids to survivin inhibitor YM155.

The interplay between α7 nicotinic acetylcholine receptors, pannexin-1 channels and P2X7 receptors elicit exocytosis in chromaffin cells.

Pannexin-1 (Panx1) forms plasma membrane channels that allow the exchange of small molecules between the intracellular and extracellular compartments, and are involved in diverse physiological and pathological responses in the nervous system. However, the signaling mechanisms that induce their opening still remain elusive. Here, we propose a new mechanism for Panx1 channel activation through a functional crosstalk with the highly Ca2+ permeable α7 nicotinic acetylcholine receptor (nAChR). Consistent with this hypothesis, we found that activation of α7 nAChRs induces Panx1-mediated dye uptake and ATP release in the neuroblastoma cell line SH-SY5Y-α7. Using membrane permeant Ca2+ chelators, total internal reflection fluorescence microscopy in SH-SY5Y-α7 cells expressing a membrane-tethered GCAMP3, and Src kinase inhibitors, we further demonstrated that Panx1 channel opening depends on Ca2+ signals localized in submembrane areas, as well as on Src kinases. In turn, Panx1 channels amplify cytosolic Ca2+ signals induced by the activation of α7 nAChRs, by a mechanism that seems to involve ATP release and P2X7 receptor activation, as hydrolysis of extracellular ATP with apyrase or blockage of P2X7 receptors with oxidized ATP significantly reduces the α7 nAChR-Ca2+ signal. The physiological relevance of this crosstalk was also demonstrated in neuroendocrine chromaffin cells, wherein Panx1 channels and P2X7 receptors contribute to the exocytotic release of catecholamines triggered by α7 nAChRs, as measured by amperometry. Together these findings point to a functional coupling between α7 nAChRs, Panx1 channels and P2X7 receptors with physiological relevance in neurosecretion.

Purinergic Receptors Crosstalk with CCR5 to Amplify Ca2+ Signaling.

Many G protein-coupled receptors (GPCRs) signal through more than one subtype of heterotrimeric G proteins. For example, the C-C chemokine receptor type 5 (CCR5), which serves as a co-receptor to facilitate cellular entry of human immunodeficiency virus 1 (HIV-1), normally signals through the heterotrimeric G protein, Gi. However, CCR5 also exhibits G protein signaling bias and certain chemokine analogs can cause a switch to Gq pathways to induce Ca2+ signaling. We want to understand how much of the Ca2+ signaling from Gi-coupled receptors is due to G protein promiscuity and how much is due to transactivation and crosstalk with other receptors. We propose a possible mechanism underlying the apparent switching between different G protein signaling pathways. We show that chemokine-mediated Ca2+ flux in HEK293T cells expressing CCR5 can be primed and enhanced by ATP pretreatment. In addition, agonist-dependent lysosomal exocytosis results in the release of ATP to the extracellular milieu, which amplifies cellular signaling networks. ATP is quickly degraded via ADP and AMP to adenosine. ATP, ADP and adenosine activate different cell surface purinergic receptors. Endogenous Gq-coupled purinergic P2Y receptors amplify Ca2+ signaling and allow for Gi- and Gq-coupled receptor signaling pathways to converge. Associated secretory release of GPCR ligands, such as chemokines, opioids, and monoamines, should also lead to concomitant release of ATP with a synergistic effect on Ca2+ signaling. Our results suggest that crosstalk between ATP-activated purinergic receptors and other Gi-coupled GPCRs is an important cooperative mechanism to amplify the intracellular Ca2+ signaling response.

Crosstalk between Androgen-ZIP9 Signaling and Notch Pathway in Rodent Sertoli Cells.

Our recent study demonstrated altered expression of Notch ligands, receptors, and effector genes in testes of pubertal rats following reduced androgen production or signaling. Herein we aimed to explore the role of nuclear androgen receptor (AR) and membrane androgen receptor (Zrt- and Irt-like protein 9; ZIP9) in the regulation of Notch pathway activation in rodent Sertoli cells. Experiments were performed using TM4 and 15P-1 Sertoli cell lines and rat primary Sertoli cells (PSC). We found that testosterone (10-8 M-10-6 M) increased the expression of Notch1 receptor, its active form Notch1 intracellular domain (N1ICD) (p < 0.05, p < 0.01, p < 0.001), and the effector genes Hey1 (p < 0.05, p < 0.01, p < 0.001) and Hes1 (p < 0.05, p < 0.001) in Sertoli cells. Knockdown of AR or ZIP9 as well as antiandrogen exposure experiments revealed that (i) action of androgens via both AR and ZIP9 controls Notch1/N1ICD expression and transcriptional activity of recombination signal binding protein (RBP-J), (ii) AR-dependent signaling regulates Hey1 expression, (iii) ZIP9-dependent pathway regulates Hes1 expression. Our findings indicate a crosstalk between androgen and Notch signaling in Sertoli cells and point to cooperation of classical and non-classical androgen signaling pathways in controlling Sertoli cell function.

Neuroprotection by Neurotropin through Crosstalk of Neurotrophic and Innate Immune Receptors in PC12 Cells.

Infected or damaged tissues release multiple "alert" molecules such as alarmins and damage-associated molecular patterns (DAMPs) that are recognized by innate immune receptors, and induce tissue inflammation, regeneration, and repair. Recently, an extract from inflamed rabbit skin inoculated with vaccinia virus (Neurotropin®, NTP) was found to induce infarct tolerance in mice receiving permanent ischemic attack to the middle cerebral artery. Likewise, we report herein that NTP prevented the neurite retraction in PC12 cells by nerve growth factor (NGF) deprivation. This effect was accompanied by interaction of Fyn with high-affinity NGF receptor TrkA. Sucrose density gradient subcellular fractionation of NTP-treated cells showed heretofore unidentified membrane fractions with a high-buoyant density containing Trk, B subunit of cholera toxin-bound ganglioside, flotillin-1 and Fyn. Additionally, these new membrane fractions also contained Toll-like receptor 4 (TLR4). Inhibition of TLR4 function by TAK-242 prevented the formation of these unidentified membrane fractions and suppressed neuroprotection by NTP. These observations indicate that NTP controls TrkA-mediated signaling through the formation of clusters of new membrane microdomains, thus providing a platform for crosstalk between neurotrophic and innate immune receptors. Neuroprotective mechanisms through the interaction with innate immune systems may provide novel mechanism for neuroprotection.

Sitagliptin and tofacitinib ameliorate adjuvant induced arthritis via modulating the cross talk between JAK/STAT and TLR-4/NF-κB signaling pathways.

AIMS: Rheumatoid arthritis is an autoimmune systemic disorder causing pain, swelling, stiffness, and disability in various joints. This work was designed to evaluate the effect of sitagliptin and tofacitinib on Janus kinase (JAK)/signaling transducer and activator of transcription (STAT) and toll like receptor (TLR-4)/nuclear factor kappa B (NF-κB) signaling pathways in adjuvant induced arthritis in rats. MATERIALS AND METHODS: Severity of arthritis was evaluated and serum was analyzed for inflammatory mediators. The mRNA and protein expression level of the most important members of the two signaling pathways were determined. Lipid profile, transaminases and renal function parameters were assessed. KEY FINDINGS: Sitagliptin and tofacitinib significantly decreased the level of inflammatory parameters, the mRNA and protein expression level of the members of JAK/STAT and TLR-4/NF-κB pathways with more prominent effect of sitagliptin on TLR-4/NF-κB pathway and more expected obvious effect of tofacitinib on JAK/STAT pathway. The combination offered additional anti-inflammatory effect by inhibiting the cross talk between these pathways as inhibition of NF-κB activation decreased the serum level of IL-6 preventing the activation of STAT-3 in tibiotarsal tissues. SIGNIFICANCE: The combination of tofacitinib and sitagliptin normalized serum lipids and blood glucose level which could offer protection against cardiovascular diseases and caused partial reversal of serum transaminases and creatinine levels which can protect against tofacitinb's related hepato and nephrotoxicity. We could conclude that the combination of Sitagliptin with tofacitinib can offer synergistic anti-inflammatory effect and more protective action against side effects of tofacitinib.

Bidirectional crosstalk between Hypoxia-Inducible Factor and glucocorticoid signalling in zebrafish larvae.

In the last decades in vitro studies highlighted the potential for crosstalk between Hypoxia-Inducible Factor-(HIF) and glucocorticoid-(GC) signalling pathways. However, how this interplay precisely occurs in vivo is still debated. Here, we use zebrafish larvae (Danio rerio) to elucidate how and to what degree hypoxic signalling affects the endogenous glucocorticoid pathway and vice versa, in vivo. Firstly, our results demonstrate that in the presence of upregulated HIF signalling, both glucocorticoid receptor (Gr) responsiveness and endogenous cortisol levels are repressed in 5 days post fertilisation larvae. In addition, despite HIF activity being low at normoxia, our data show that it already impedes both glucocorticoid activity and levels. Secondly, we further analysed the in vivo contribution of glucocorticoids to HIF activity. Interestingly, our results show that both glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) play a key role in enhancing it. Finally, we found indications that glucocorticoids promote HIF signalling via multiple routes. Cumulatively, our findings allowed us to suggest a model for how this crosstalk occurs in vivo.

Cross-talk between dopamine D1 and corticotropin releasing factor type 2 receptors leads to occlusion of their ERK1/2 signaling.

One manner in which G protein-coupled receptors potentiate, increase, and change their functionality is through the formation of heteromers in a specific cellular context. Previously, we have shown that dopamine D1 receptor (D1R) and the corticotropin releasing factor receptor type-2α (CRF2α) heteromerize in HEK293T cells, enabling D1R to mobilize intracellular calcium in response to D1R agonists. In this study, we further investigated the pharmacological properties of the CRF2α-D1R heteromer and the consequences of the heteromerization in their signaling and subcellular localization when both receptors are co-expressed in HEK293T cells. Using immunoprecipitation assays, we observed that the addition of 10 µM dopamine in the incubation medium significantly decreased the amount of CRF2α on the cell surface of cells expressing both receptors. The presence of agonists of both receptors increased the interaction between CRF2α and D1R as assessed by co-immunoprecipitation. However, the presence of agonists of both receptors resulted in a lesser efficient activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase. Using a synaptosomal preparation of rat prefrontal cortex devoid of post-synaptic elements, we found that CRF2α and D1R co-localize in synaptic terminals of the rat medial prefrontal cortex and that the simultaneous activation of both receptors also occluded phosphorylation of extracellular signal-regulated kinase. These results strengthen the idea that the heteromer CRF2a-D1R is an entity functionally different from each receptor that composes it and suggests that its formation is enhanced by CRF and dopamine co-transmission, as occurs in stress and addiction.

TSH/IGF1 receptor crosstalk: Mechanism and clinical implications.

Increasing evidence of interdependence between G protein-coupled receptors and receptor tyrosine kinase signaling pathways has prompted reevaluation of crosstalk between these receptors in disease and therapy. Investigations into thyroid-stimulating hormone (TSH) and insulin-like growth factor 1 (IGF1) receptor crosstalk, and its application to the clinic have in particular shown recent progress. In this review, we summarize current insights into the mechanism of TSH/IGF1 receptor crosstalk. We discuss evidence that crosstalk is one of the underlying causes of TSHR-based disease and the feasibility of using combinations of TSH receptor and IGF1 receptor antagonists to increase the therapeutic index for the treatment of Graves' hyperthyroidism and Graves' ophthalmopathy.

In Vitro Investigation Demonstrates IGFR/VEGFR Receptor Cross Talk and Potential of Combined Inhibition in Pediatric Central Nervous System Atypical Teratoid Rhabdoid Tumors.

BACKGROUND: Atypical teratoid rhabdoid tumor of the central nervous system (CNS ATRT) is a malignancy that commonly affects young children. The biological mechanisms contributing to tumor aggressiveness and resistance to conventional therapies in ATRT are unknown. Previous studies have shown the activity of insulin like growth factor-I receptor (IGF-1R) in ATRT tumor specimens and cell lines. IGF-1R has been shown to cross-talk with other receptor tyrosine kinases (RTKs) in a number of cancer types, leading to enhanced cell proliferation. OBJECTIVE: This study aims to evaluate the role of IGF-1 receptor cross-talk in ATRT biology and the potential for therapeutic targeting. METHODS: Cell lines derived from CNS ATRT specimens were analyzed for IGF-1 mediated cell proliferation. A comprehensive receptor tyrosine kinase (RTK) screen was conducted following IGF-1 stimulation. Bioinformatic analysis of publicly available cancer growth inhibition data to identify correlation between IC50 of a VEGFR inhibitor and IGF-1R expression. RESULTS: Comprehensive RTK screen identified VEGFR-2 cross-activation following IGF-1 stimulation. Bioinformatics analysis demonstrated a positive correlation between IC50 values of VEGFR inhibitor Axitinib and IGF-1R expression, supporting the critical influence of IGF-1R in modulating response to anti-angiogenic therapies. CONCLUSION: Overall, our data present a novel experimental framework to evaluate and utilize receptor cross-talk mechanisms to select effective drugs and combinations for future therapeutic trials in ATRT.

Intracellular Signals Activated by Canonical Wnt Ligands Independent of GSK3 Inhibition and ß-Catenin Stabilization.

In contrast to non-canonical ligands, canonical Wnts promote the stabilization of ß-catenin, which is a prerequisite for formation of the TCF4/ß-catenin transcriptional complex and activation of its target genes. This pathway is initiated by binding of Wnt ligands to the Frizzled/LRP5/6 receptor complex, and it increases the half-life of ß-catenin by precluding the phosphorylation of ß-catenin by GSK3 and its binding to the ßTrCP1 ubiquitin ligase. Other intercellular signals are also activated by Wnt ligands that do not inhibit GSK3 and increase ß-catenin protein but that either facilitate ß-catenin transcriptional activity or stimulate other transcriptional factors that cooperate with it. In this review, we describe the layers of complexity of these signals and discuss their crosstalk with ß-catenin in activation of transcriptional targets.

The implication of the crosstalk of Nrf2 with NOXs, and HMGB1 in ethanol-induced gastric ulcer: Potential protective effect is afforded by Raspberry Ketone.

Ethanol consumption is one of the common causative agents implicated in gastric ulcer development. Oxidative stress plays a major role in the induction and development of gastric ulceration. NADPH oxidases (NOXs) and Nuclear factor erythroid 2-related factor 2 (Nrf2) are key players in ethanol-induced ulcers. High-mobility group box 1 (HMGB1), a ubiquitous nuclear protein, mediates various inflammation functions. However, the role of HMGB1 in ethanol-induced gastric ulcer is not yet elucidated. Raspberry Ketone (RK) is a natural phenolic compound with antioxidant and anti-inflammatory properties. In the present study, absolute ethanol (7.5 ml/kg) was used to induce gastric ulceration in rats. Raspberry Ketone (RK) (50 mg/kg) was given orally one hour before the administration of absolute ethanol. Interestingly, ethanol-induced gastric ulcer was associated with Nrf2 downregulation, which was correlated with NOX-1, 2 NOX-4, and HMGB1 upregulation, and was significantly reversed by RK pre-treatment. RK pre-treatment provided 80% gastroprotection. Gastroprotective properties of RK were mediated via antioxidant, anti-inflammatory (suppression of NF-kB and tumor necrosis factor-α), and antiapoptotic activities (reduction of Bax/Bcl2 ratio). Gastroprotective properties of RK were confirmed by histopathological examination. In conclusion, this study is the first to provide evidence to the role of HMGB1 in ethanol-induced gastric ulcer, and the crosstalk of Nrf2, NOXs and HMGB1. It also demonstrates that RK represents a promising gastroprotective activity comparable to omeprazole.

Co-targeting of endothelin-A and vitamin D receptors: a novel strategy to ameliorate cisplatin-induced nephrotoxicity.

BACKGROUND: Although modulation of the vitamin D receptor (VDR) and endothelin-A receptor (ETAR) has previously been reported to offer renoprotection against cisplatin-induced nephrotoxicity, the possible interaction between the ET-1 and vitamin D pathways remains obscure. Therefore, the present study addressed the possible interaction between these signalling pathways using BQ-123 (a selective ETAR blocker) and alfacalcidol (a vitamin D3 analogue) separately or in combination. METHODS: Male Sprague-Dawley rats were divided into the following groups: control (DMSO orally), cisplatin (single dose of 6 mg/kg ip; nephrotoxicity model), cisplatin + BQ-123 (1 mg/kg BQ-123 ip 1 h before and 1 day after cisplatin), cisplatin + alfacalcidol (50 ng/kg alfacalcidol orally 5 days before and 14 days after cisplatin), and cisplatin + BQ-123+alfacalcidol. Nephrotoxicity was evaluated 96 h and 14 days following cisplatin administration. RESULTS: Both BQ-123 and alfacalcidol counteracted cisplatin-induced nephrotoxic changes. Specifically, they reduced serum creatinine and urea levels; renal tumour necrosis factor-alpha (TNF-α), transforming growth factor-beta1 (TGF-ß1), and phosphorylated nuclear factor-kappa B (pNF-κB) content; and caspase-3 activity. They downregulated ET-1 and ETAR expression and ameliorated cisplatin-induced acute tubular necrosis. In addition, the treatments have increased VDR and endothelin-B receptor (ETBR) expression; however, BQ-123 did not affect ETBR. The effect of the combination regimen surpassed that of each drug alone. CONCLUSION: These findings highlight the potential cross-talk between vitamin D and ET-1 pathways and pave the way for future preclinical/clinical studies to explore further mechanisms involved in this cross-talk.

Crosstalk between tumor cells and lymphocytes modulates heparanase expression.

BACKGROUND: Heparanase (HPSE) is an endo-beta-glucuronidase that degrades heparan sulfate (HS) chains on proteoglycans. The oligosaccharides generated by HPSE promote angiogenesis, tumor growth and metastasis. Heparanase-2 (HPSE2), a close homolog of HPSE, does not exhibit catalytic activity. Previous studies have demonstrated that serum or plasma from breast cancer patients showed increased expression of both heparanases in circulating lymphocytes. The aim of this study was to better understand the mechanisms involved in the upregulation of heparanases in circulating lymphocytes. METHODS: Lymphocytes collected from healthy women were incubated in the presence of MCF-7 breast cancer cells (co-culture) to stimulate HPSE and HPSE2 overexpression. The protein level of heparanases was evaluated by immunocytochemistry, while mRNA expression was determined by quantitative RT-PCR. RESULTS: The medium obtained from co-culture of MCF-7 cells and circulating lymphocytes stimulated the expression of HPSE and HPSE2. Previous treatment of the co-culture medium with an anti-heparan sulfate proteoglycan antibody or heparitinase II inhibited the upregulation of heparanases in circulating lymphocytes. The addition of exogenous heparan sulfate (HS) enhanced the expression of both heparanases. Moreover, the co-cultured cells, as well as MCF-7 cells, secreted a higher number of exosomes expressing an increased level of HS compared to that of the exosomes secreted by circulating lymphocytes from women who were not affected by cancer. CONCLUSIONS: The results revealed that HS is likely responsible for mediating the expression of heparanases in circulating lymphocytes. HS secreted by tumor cells might be carried by exosome particles, confirming the key role of tumor cells, as well as secreted HS, in upregulating the expression of heparanases, suggesting a possible mechanism of crosstalk between tumor cells and circulating lymphocytes.

A novel leptin receptor antagonist uncouples leptin's metabolic and immune functions.

Leptin links body energy stores to high energy demanding processes like reproduction and immunity. Based on leptin's role in autoimmune diseases and cancer, several leptin and leptin receptor (LR) antagonists have been developed, but these intrinsically lead to unwanted weight gain. Here, we report on the uncoupling of leptin's metabolic and immune functions based on the cross talk with the epidermal growth factor receptor (EGFR). We show that both receptors spontaneously interact and, remarkably, that this complex can partially overrule the lack of LR activation by a leptin antagonistic mutein. Moreover, this leptin mutant induces EGFR phosphorylation comparable to wild-type leptin. Exploiting this non-canonical leptin signalling pathway, we identified a camelid single-domain antibody that selectively inhibits this LR-EGFR cross talk without interfering with homotypic LR signalling. Administration in vivo showed that this single-domain antibody did not interfere with leptin's metabolic functions, but could reverse the leptin-driven protection against starvation-induced thymic and splenic atrophy. These findings offer new opportunities for the design and clinical application of selective leptin and LR antagonists that avoid unwanted metabolic side effects.

Compensatory role of insulin-like growth factor 1 receptor in estrogen receptor signaling pathway and possible therapeutic target for hormone therapy-resistant breast cancer.

BACKGROUND: Hormone therapy targeting the estrogen receptor (ER) pathway is the most common treatment used for ER-positive breast cancer. However, some patients experience de novo or acquired resistance, which becomes a critical problem. Activation of the insulin-like growth factor (IGF) pathway allows breast cancer cells to proliferate and is associated with the ER pathway. Little is known about the role of the IGF pathway in hormone therapy and resistance; therefore, we investigated whether the inhibition of this pathway may represent a novel therapeutic target for overcoming hormone therapy resistance in ER-positive breast cancers. METHODS: Crosstalk between the ER and IGF pathways was analyzed in breast cancer cell lines by inhibiting or stimulating either one or both pathways. We studied the effect of insulin-like growth factor one receptor (IGF1R) inhibition in aromatase inhibitor-resistant breast cancer cell lines and fulvestrant-resistant cell lines which were uniquely established in our laboratory. RESULTS: Under normal conditions, IGF signaling is controlled by ER signaling to promote cell growth. Temporary disruption of the estrogen supply results in attenuated ER signaling, and IGF-1 dramatically increased relative growth compared with normal conditions. In addition, IGF1R inhibitor strongly suppressd cell growth in hormone-resistant breast cancer cells where ER remains than cells where ER decreased or was almost lost. CONCLUSIONS: Our study suggests that inhibition of the IGF pathway may be an effective strategy for ER-positive breast cancer therapy, even in hormone therapy-resistant cases.