Bridgehead Modifications of Englerin A Reduce TRPC4 Activity and Intravenous Toxicity but not Cell Growth Inhibition.
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ABSTRACT:
SUBMITTER: Wu Z
PROVIDER: S-EPMC7488277 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Recently, we found that the deletion of TRPC5 leads to increased inflammation and pain-related behaviour in two animal models of arthritis. (-)-Englerin A (EA), an extract from the East African plant Phyllanthus engleri has been identified as a TRPC4/5 agonist. Here, we studied whether or not EA has any anti-inflammatory and analgesic properties via TRPC4/5 in the carrageenan model of inflammation. We found that EA treatment in CD1 mice inhibited thermal hyperalgesia and mechanical allodynia in a dose-dependent manner. Furthermore, EA significantly reduced the volume of carrageenan-induced paw oedema and the mass of the treated paws. Additionally, in dorsal root ganglion (DRG) neurons cultured from WT 129S1/SvIm mice, EA induced a dose-dependent cobalt uptake that was surprisingly preserved in cultured DRG neurons from 129S1/SvIm TRPC5 KO mice. Likewise, EA-induced anti-inflammatory and analgesic effects were preserved in the carrageenan model in animals lacking TRPC5 expression or in mice treated with TRPC4/5 antagonist ML204.This study demonstrates that while EA activates a sub-population of DRG neurons, it induces a novel TRPC4/5-independent analgesic and anti-inflammatory effect in vivo. Future studies are needed to elucidate the molecular and cellular mechanisms underlying EA's anti-inflammatory and analgesic effects.
| S-EPMC8232259 | biostudies-literature
Project description:Current therapies for common types of cancer such as renal cell cancer are often ineffective and unspecific, and novel pharmacological targets and approaches are in high demand. Here we show the unexpected possibility for the rapid and selective killing of renal cancer cells through activation of calcium-permeable nonselective transient receptor potential canonical (TRPC) calcium channels by the sesquiterpene (-)-englerin?A. This compound was found to be a highly efficient, fast-acting, potent, selective, and direct stimulator of TRPC4 and TRPC5 channels. TRPC4/5 activation through a high-affinity extracellular (-)-englerin?A binding site may open up novel opportunities for drug discovery aimed at renal cancer.
| S-EPMC7116557 | biostudies-literature
Project description:Englerin A is a structurally unique natural product reported to selectively inhibit growth of renal cell carcinoma cell lines. A large scale phenotypic cell profiling experiment (CLiP) of englerin A on ¬over 500 well characterized cancer cell lines showed that englerin A inhibits growth of a subset of tumor cell lines from many lineages, not just renal cell carcinomas. Expression of the TRPC4 cation channel was the cell line feature that best correlated with sensitivity to englerin A, suggesting the hypothesis that TRPC4 is the efficacy target for englerin A. Genetic experiments demonstrate that TRPC4 expression is both necessary and sufficient for englerin A induced growth inhibition. Englerin A induces calcium influx and membrane depolarization in cells expressing high levels of TRPC4 or its close ortholog TRPC5. Electrophysiology experiments confirmed that englerin A is a TRPC4 agonist. Both the englerin A induced current and the englerin A induced growth inhibition can be blocked by the TRPC4/C5 inhibitor ML204. These experiments confirm that activation of TRPC4/C5 channels inhibits tumor cell line proliferation and confirms the TRPC4 target hypothesis generated by the cell line profiling. In selectivity assays englerin A weakly inhibits TRPA1, TRPV3/V4, and TRPM8 which suggests that englerin A may bind a common feature of TRP ion channels. In vivo experiments show that englerin A is lethal in rodents near doses needed to activate the TRPC4 channel. This toxicity suggests that englerin A itself is probably unsuitable for further drug development. However, since englerin A can be synthesized in the laboratory, it may be a useful chemical starting point to identify novel modulators of other TRP family channels.
| S-EPMC4476799 | biostudies-literature
Project description:The sesquiterpene (-)Englerin A (EA) is an organic compound from the plant Phyllanthus engleri which acts via heteromeric TRPC4/C1 channels to cause cytotoxicity in some types of cancer cell but not normal cells. Here we identified selective cytotoxicity of EA in human synovial sarcoma cells (SW982 cells) and investigated the mechanism. EA induced cation channel current (Icat) in SW982 cells with biophysical characteristics of heteromeric TRPC4/C1 channels. Inhibitors of homomeric TRPC4 channels were weak inhibitors of the Icat and EA-induced cytotoxicity whereas a potent inhibitor of TRPC4/C1 channels (Pico145) strongly inhibited Icat and cytotoxicity. Depletion of TRPC1 converted Icat into a current with biophysical and pharmacological properties of homomeric TRPC4 channels and depletion of TRPC1 or TRPC4 suppressed the cytotoxicity of EA. A Na+/K+-ATPase inhibitor (ouabain) potentiated EA-induced cytotoxicity and direct Na+ loading by gramicidin-A caused Pico145-resistant cytotoxicity in the absence of EA. We conclude that EA has a potent cytotoxic effect on human synovial sarcoma cells which is mediated by heteromeric TRPC4/C1 channels and Na+ loading.
| S-EPMC5717101 | biostudies-literature
Project description:(-)-Englerin A (EA) is a natural product which has potent cytotoxic effects on renal cell carcinoma cells and other types of cancer cell but not non-cancer cells. Although selectively cytotoxic to cancer cells, adverse reaction in mice and rats has been suggested. EA is a remarkably potent activator of ion channels formed by Transient Receptor Potential Canonical 4 and 5 proteins (TRPC4 and TRPC5) and TRPC4 is essential for EA-mediated cancer cell cytotoxicity. Here we specifically investigated the relevance of TRPC4 and TRPC5 to the adverse reaction. Injection of EA (2 mg.kg-1 i.p.) adversely affected mice for about 1 hour, manifesting as a marked reduction in locomotor activity, after which they fully recovered. TRPC4 and TRPC5 single knockout mice were partially protected and double knockout mice fully protected. TRPC4/TRPC5 double knockout mice were also protected against intravenous injection of EA. Importance of TRPC4/TRPC5 channels was further suggested by pre-administration of Compound 31 (Pico145), a potent and selective small-molecule inhibitor of TRPC4/TRPC5 channels which did not cause adverse reaction itself but prevented adverse reaction to EA. EA was detected in the plasma but not the brain and so peripheral mechanisms were implicated but not identified. The data confirm the existence of adverse reaction to EA in mice and suggest that it depends on a combination of TRPC4 and TRPC5 which therefore overlaps partially with TRPC4-dependent cancer cell cytotoxicity. The underlying nature of the observed adverse reaction to EA, as a consequence of TRPC4/TRPC5 channel activation, remains unclear and warrants further investigation.
| S-EPMC6049859 | biostudies-other
Project description:The ring closing metathesis/transannular etherification approach to the englerin nucleus was adapted to provide two key intermediates for analogue synthesis: the 4-desmethyl ?5,6 tricycle and the 4-oxo ?5,6 tricycle. The former was elaborated to 4-desmethyl englerin A and the latter served as a common precursor for englerin A, 4-ethyl englerin A, and 4-isopropyl englerin A. 4-Desmethyl englerin A was less active than the natural product by an order of magnitude, but the 4-ethyl and 4-isopropyl analogues were comparable in activity to englerin A. These results are consistent with the premise that the 4-alkyl group enforces the binding conformation of the cinnamoyl ester substituent. Furthermore, they suggest that 4-alkyl englerin structures may prove to be useful tool compounds.
| S-EPMC5512125 | biostudies-literature
Project description:An extract from Phyllanthus engleri was identified in a bioinformatic analysis of NCI 60-cell natural product extract screening data that selectively inhibited the growth of renal cancer cell lines. Bioassay-guided fractionation yielded two new guaiane sesquiterpenes, englerins A (1) and B (2). Englerin A showed 1000-fold selectivity against six of eight renal cancer cell lines with GI(50) values ranging from 1-87 nM. The structures of 1 and 2 and their relative stereochemistry were established by spectroscopic methods.
| S-EPMC2651161 | biostudies-literature
Project description:BackgroundAlthough animal experiments suggest beneficial effects of physical activity (PA) on antitumor immunity, little is known about the effects of PA on immune checkpoint inhibitor (ICI) toxicity and effectiveness in humans. We assessed the association of PA with immune-related adverse events (irAE) and survival in patients undergoing ICI.MethodsPatients receiving ICI who completed the Dutch short questionnaire to assess health enhancing physical activity (SQUASH) questionnaire at the start of treatment as part of the prospective UNICIT study in an academic hospital were included. PA was quantified by calculating total metabolic equivalent task hours per week (total PA) and hours per week of moderate- to vigorous-intensity PA during sport and leisure time (MVPA-SL). Associations of PA with severe irAE occurrence within 1 year and overall survival (OS) were evaluated using logistic regression and Cox proportional hazard regression, respectively, with adjustment for probable confounders.ResultsIn total, 251 patients were included, with a median follow-up of 20 months. Moderate and high levels of total PA were associated with lower odds of severe irAE occurrence compared to low levels of total PA (adjusted OR: 0.34 [95% CI = 0.12 to 0.90] and 0.19 [95% CI = 0.05 to 0.55], respectively). Moderate and high levels of total PA were also associated with prolonged survival (adjusted HR: 0.58 [95% CI = 0.32 to 1.04] and 0.48 [95% CI = 0.27 to 0.89], respectively). Similar associations were observed in patients who performed more MVPA-SL.ConclusionsHigher physical activity levels at the start of ICI treatment are associated with lower risk of severe irAEs and probably prolonged survival. Randomized controlled trials are needed to investigate whether patients indeed benefit from increasing PA levels after diagnosis.
| S-EPMC10995850 | biostudies-literature
Project description:The Transient Receptor Potential Channel Subunit 4 (TRPC4) has been considered as a crucial Ca2+ component in cardiomyocytes promoting structural and functional remodeling in the course of pathological cardiac hypertrophy. TRPC4 assembles as homo or hetero-tetramer in the plasma membrane, allowing a non-selective Na+ and Ca2+ influx. G?q protein-coupled receptor (GPCR) stimulation is known to increase TRPC4 channel activity and a TRPC4-mediated Ca2+ influx which has been regarded as ideal Ca2+ source for calcineurin and subsequent nuclear factor of activated T-cells (NFAT) activation. Functional properties of TRPC4 are also based on the expression of the TRPC4 splice variants TRPC4? and TRPC4?. Aim of the present study was to analyze cytosolic Ca2+ signals, signaling, hypertrophy and vitality of cardiomyocytes in dependence on the expression level of either TRPC4? or TRPC4?. The analysis of Ca2+ transients in neonatal rat cardiomyocytes (NRCs) showed that TRPC4? and TRPC4? affected Ca2+ cycling in beating cardiomyocytes with both splice variants inducing an elevation of the Ca2+ transient amplitude at baseline and TRPC4? increasing the Ca2+ peak during angiotensin II (Ang II) stimulation. NRCs infected with TRPC4? (Ad-C4?) also responded with a sustained Ca2+ influx when treated with Ang II under non-pacing conditions. Consistent with the Ca2+ data, NRCs infected with TRPC4? (Ad-C4?) showed an elevated calcineurin/NFAT activity and a baseline hypertrophic phenotype but did not further develop hypertrophy during chronic Ang II/phenylephrine stimulation. Down-regulation of endogenous TRPC4? reversed these effects, resulting in less hypertrophy of NRCs at baseline but a markedly increased hypertrophic enlargement after chronic agonist stimulation. Ad-C4? NRCs did not exhibit baseline calcineurin/NFAT activity or hypertrophy but responded with an increased calcineurin/NFAT activity after GPCR stimulation. However, this effect was not translated into an increased propensity towards hypertrophy but rather less hypertrophy during GPCR stimulation. Further analyses revealed that, although hypertrophy was preserved in Ad-C4? NRCs and even attenuated in Ad-C4? NRCs, cardiomyocytes had an increased apoptosis rate and thus were less viable after chronic GPCR stimulation. These findings suggest that TRPC4? and TRPC4? differentially affect Ca2+ signals, calcineurin/NFAT signaling and hypertrophy but similarly impair cardiomyocyte viability during GPCR stimulation.
| S-EPMC5167390 | biostudies-literature
Project description:KEY POINTS:Increased activation of the renin-angiotensin-aldosterone system (RAAS) and elevated growth factor production are of crucial importance in the development of renal fibrosis leading to diabetic kidney disease. The aim of this study was to provide evidence for the antifibrotic potential of RAAS inhibitor (RAASi) treatment and to explore the exact mechanism of this protective effect. We found that RAASi ameliorate diabetes-induced renal interstitial fibrosis and decrease profibrotic growth factor production. RAASi prevents fibrosis by acting directly on proximal tubular cells, and inhibits hyperglycaemia-induced growth factor production and thereby fibroblast activation. These results suggest a novel therapeutic indication and potential of RAASi in the treatment of renal fibrosis. ABSTRACT:In diabetic kidney disease (DKD) increased activation of renin-angiotensin-aldosterone system (RAAS) contributes to renal fibrosis. Although RAAS inhibitors (RAASi) are the gold standard therapy in DKD, the mechanism of their antifibrotic effect is not yet clarified. Here we tested the antifibrotic and renoprotective action of RAASi in a rat model of streptozotocin-induced DKD. In vitro studies on proximal tubular cells and renal fibroblasts were also performed to further clarify the signal transduction pathways that are directly altered by hyperglycaemia. After 5 weeks of diabetes, male Wistar rats were treated for two more weeks per os with the RAASi ramipril, losartan, spironolactone or eplerenone. Proximal tubular cells were cultured in normal or high glucose (HG) medium and treated with RAASi. Platelet-derived growth factor (PDGF) or connective tissue growth factor (CTGF/CCN2)-induced renal fibroblasts were also treated with various RAASi. In diabetic rats, reduced renal function and interstitial fibrosis were ameliorated and elevated renal profibrotic factors (TGF?1, PDGF, CTGF/CCN2, MMP2, TIMP1) and alpha-smooth muscle actin (?SMA) levels were decreased by RAASi. HG increased growth factor production of HK-2 cells, which in turn induced activation and ?SMA production of fibroblasts. RAASi decreased tubular PDGF and CTGF expression and reduced production of extracellular matrix (ECM) components in fibroblasts. In proximal tubular cells, hyperglycaemia-induced growth factor production increased renal fibroblast transformation, contributing to the development of fibrosis. RAASi, even in non-antihypertensive doses, decreased the production of profibrotic factors and directly prevented fibroblast activation. All these findings suggest a novel therapeutic role for RAASi in the treatment of renal fibrosis.
| S-EPMC6312411 | biostudies-literature