Screening and Validation of Aquaporin Inhibitors for Cancer Therapeutics

Aquaporins (AQPs) are transmembrane proteins that facilitate the diffusion of water and glycerol across cell membranes, crucial for water and energy homeostasis. These proteins were found overexpressed in different cancer cells and tissues, being involved in tumor formation, cell proliferation and migration, suggesting their great potential as drug targets for cancer treatment. Identification of novel aquaporin modulators to be used in cancer therapeutics is of utmost importance. In this study, the inhibitory effect of polyoxometalates, vanadium, copper, zinc and gold-based compounds was screened by the stopped-flow technique in human red blood cells (RBCs) and then validated in aquaporin-expressing yeast cells. From the set of polyoxometalates, polyoxotungstate-A (POT-A) revealed as the most promising AQP3 inhibitor with an IC50 of (0.71 ± 0.04) μM. Using yeast cells individually expressing human aquaporins, POT-A showed to selectively inhibit AQP3 with 100% inhibition, corroborating the results of RBCs assays. The vanadium compound P103, showed highly inhibition of AQP1 with an IC50 of (9.11 ± 0.03) μM in RBCs. The gold-based compound RBA29 revealed as a promising AQP3 inhibitor with an IC50 of (2.29 ± 0.03) μM in RBCs. Moreover, compounds RBA29, RBA31 and STAM013 showed an inhibitory effect in AQP9-tranformed yeasts, with an IC50 of (6.64 ± 0.09) μM for RBA29. In addition, investigation of the channel residues important for AQP5 permeability revealed a new gating mechanism where His73 located in the selectivity filter interacts with phosphorylated Ser183, conducting to the pore constriction. Furthermore, the activity of aquaporins from diverse organisms was evaluated, wherein aquaporin from tardigrade revealed to be water selective and exhibited higher water permeability than the other aquaporins tested. Overall, these data contribute to the discovery and design of selective inhibitors with potential therapeutic application

The aquaporin-3-inhibiting potential of polyoxotungstates

Polyoxometalates (POMs) are of increasing interest due to their proven anticancer activities. Aquaporins (AQPs) were found to be overexpressed in tumors bringing particular attention to their inhibitors as anticancer drugs. Herein, we report for the first time the ability of polyoxotungstates (POTs), such as of Wells-Dawson P2W18, P2W12, and P2W15, and Preyssler P5W30 structures, to affect aquaporin-3 (AQP3) activity and impair melanoma cell migration. The tested POTs were revealed to inhibit AQP3 function with different effects, with P2W18, P2W12, and P5W30 being the most potent (50% inhibitory concentration (IC50) = 0.8, 2.8, and 3.2 µM), and P2W15 being the weakest (IC50 > 100 µM). The selectivity of P2W18 toward AQP3 was confirmed in yeast cells transformed with human aquaglyceroporins. The effect of P2W12 and P2W18 on melanoma cells that highly express AQP3 revealed an impairment of cell migration between 55% and 65% after 24 h, indicating that the anticancer properties of these compounds may in part be due to the blockage of AQP3-mediated permeability. Altogether, our data revealed that P2W18 strongly affects AQP3 activity and cancer cell growth, unveiling its potential as an anticancer drug against tumors where AQP3 is highly expressed.Fundação para a Ciência e a Tecnologia (FCT) (PTDC/BTM-SAL/28977/2017, PTDC/MED-QUI/31721/2017, UID/DTP/04138/2019, UIDB/04326/2020, SFRH/BD/117586/2016. Austrian Science Fund (FWF) P27534, M2203info:eu-repo/semantics/publishedVersio

Human aquaporin-5 facilitates hydrogen peroxide permeation affecting adaption to oxidative stress and cancer cell migration

Reactive oxygen species (ROS), including H2O2, contribute to oxidative stress and may cause cancer initiation and progression. However, at low concentrations, H2O2 can regulate signaling pathways modulating cell growth, differentiation, and migration. A few mammalian aquaporins (AQPs) facilitate H2O2 diffusion across membranes and participate in tumorigenesis. AQP3 and AQP5 are strongly expressed in cancer tissues and AQP3-mediated H2O2 transport has been related to breast cancer cell migration, but studies with human AQP5 are lacking. Here, we report that, in addition to its established water permeation capacity, human AQP5 facilitates transmembrane H2O2 diffusion and modulates cell growth of AQP5-transformed yeast cells in response to oxidative stress. Mutagenesis studies revealed that residue His173 located in the selective filter is crucial for AQP5 permeability, and interactions with phosphorylated Ser183 may regulate permeation through pore blockage. Moreover, in human pancreatic cancer cells, the measured AQP5-mediated H2O2 influx rate indicates the presence of a highly efficient peroxiporin activity. Cell migration was similarly suppressed by AQP3 or AQP5 gene silencing and could be recovered by external oxidative stimuli. Altogether, these results unveiled a major role for AQP5 in dynamic fine-tuning of the intracellular H2O2 concentration, and consequently in activating signaling networks related to cell survival and cancer progression, highlighting AQP5 as a promising drug target for cancer therapies

Glutamine and cystine-enriched diets modulate aquaporins gene expression in the small intestine of piglets

Research Areas: Science & Technology ; Other TopicsABSTRACT - The regulation of glycerol permeability in the gastrointestinal tract is crucial to control fat deposition, lipolysis and gluconeogenesis. Knowing that the amino acid glutamine is a physiological regulator of gluconeogenesis, whereas cystine promotes adiposity, herein we investigated the effects of dietary supplementation with glutamine and cystine on the serum biochemical parameters of piglets fed on amino acid-enriched diets, as well as on the transcriptional profile of membrane water and glycerol channels aquaporins (AQPs) in the ileum portion of the small intestine and its impact on intestinal permeability. Twenty male piglets with an initial body weight of 8.8 ± 0.89 kg were allocated to four dietary treatments (n = 5) and received, during a four week-period, a basal diet without supplementation (control) or supplemented with 8 kg/ton of glutamine (Gln), cystine (Cys) or the combination of the two amino acids in equal proportions (Gln + Cys). Most biochemical parameters were found improved in piglets fed Gln and Cys diet. mRNA levels of AQP3 were found predominant over the others. Both amino acids, individually or combined, were responsible for a consistent downregulation of AQP1, AQP7 and AQP10, without impacting on water permeability. Conversely, Cys enriched diet upregulated AQP3 enhancing basolateral membranes glycerol permeability and downregulating glycerol kinase (GK) of intestinal cells. Altogether, our data reveal that amino acids dietary supplementation can modulate intestinal AQPs expression and unveil AQP3 as a promising target for adipogenesis regulation.info:eu-repo/semantics/publishedVersio

Aryl hydrocarbon receptor and cysteine redox dynamics underlie (Mal)adaptive mechanisms to chronic intermittent hypoxia in kidney cortex

Funding Information: Funding: This work was supported by Fundação para Ciência e Tecnologia [PTDC/MED-TOX/30418/2017] and iNOVA4Health [UID/Multi/04462/2013]. M.J.C., F.L.-C., N.R.C., C.G.-D. and J.M. are supported by FCT grants [SFRH/BD/131331/2017, PD/BD/128337/2017, PD/BD/114257/2016, and PD/BD/105892/2014, PTDC/MED-TOX/30418/2017 respectively]. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.We hypothesized that an interplay between aryl hydrocarbon receptor (AhR) and cysteine-related thiolome at the kidney cortex underlies the mechanisms of (mal)adaptation to chronic intermittent hypoxia (CIH), promoting arterial hypertension (HTN). Using a rat model of CIH-HTN, we investigated the impact of short-term (1 and 7 days), mid-term (14 and 21 days, pre-HTN), and long-term intermittent hypoxia (IH) (up to 60 days, established HTN) on Cyp1a1 protein level (a sensitive hallmark of AhR activation) and cysteine-related thiol pools. We found that acute and chronic IH had opposite effects on Cyp1a1 and the thiolome. While short-term IH decreased Cyp1a1 and increased protein-S-thiolation, long-term IH increased Cyp1a1 and free oxidized cysteine. In addition, an in vitro administration of cystine, but not cysteine, to human endothelial cells increased Cyp1a1 expression, supporting cystine as a putative AhR activator. This study supports Cyp1a1 as a biomarker of obstructive sleep apnea (OSA) severity and oxidized pools of cysteine as risk indicator of OSA-HTN. This work contributes to a better understanding of the mechanisms underlying the phenotype of OSA-HTN, mimicked by this model, which is in line with precision medicine challenges in OSA.publishersversionpublishe

Chemical characterization and bioactivity of phytochemicals from Iberian endemic Santolina semidentata and strategies for ex situ propagation

Asteraceae family members are well-known for their medicinal potential, comprising several properties that make them unique among plants. Here we focus on Santolina semidentata, an endemic plant from the Iberian Peninsula, not yet described for its medicinal properties. Phytochemical characterization of S. semidentata was performed, concerning total phenol content, flavonoid content, antioxidant capacity, HPLC-DAD profile, acetylcholinesterase inhibitory capacity, cytotoxicity and neuroprotective effect in a human neurodegeneration cell model. Moreover, essential oil composition and antifungal activity were also analised. This oil might be useful for therapeutical purposes, particularly in the treatment of dermatophytosis. S. semidentata potential for neuroprotection was revealed by acetylcholinesterase inhibitory capacity and also by an effective protective effect in human neuronal cells. Furthermore, different seed conservation protocols, as well as successful in vitro propagation were established which may be useful when integrated in a broad strategy for the conservation of these endemic plants and their sustainable use for potential biotechnological applications. The results presented here greatly contribute to value this species regarding its potential as a source of phytochemicals with prospective neuroprotective health benefits, either as alternative neuroprotective drugs or as leads for synthetizing more effective molecules.The authors wish to thank to “Fundo EDP para a Biodiversidade” for financial support. This work was also supported by “Fundação para a Ciência e a Tecnologia” through grant PEst-OE/EQB/LA0004/2011, BGCT/33418/2008, Green-it: UID/Multi/04551/2013, iNOVA4Health: UID/Multi/04462/2013 and financial support to CNS (IF/01097/20132), RP (SFRH/BD/63615/2009), IF (SFRH/BD/86584/2012) and AG (SFRH/BD/103155/2014).info:eu-repo/semantics/publishedVersio

Cysteine as a Multifaceted Player in Kidney, the Cysteine-Related Thiolome and Its Implications for Precision Medicine

Funding Information: This research was supported by Fundação para a Ciência e Tecnologia (PTDC/MED-TOX/30418/2017) and iNOVA4Health (UID/Multi/04462/2013). M.J.C., D.G.F.F. and J.M. were supported by FCT (PhD grant SFRH/BD/131331/2017, PhD grant PD/BD/135484/2018 and postdoctoral contract PTDC/MED-TOX/30418/2017, respectively).In this review encouraged by original data, we first provided in vivo evidence that the kidney, comparative to the liver or brain, is an organ particularly rich in cysteine. In the kidney, the total availability of cysteine was higher in cortex tissue than in the medulla and distributed in free reduced, free oxidized and protein-bound fractions (in descending order). Next, we provided a comprehensive integrated review on the evidence that supports the reliance on cysteine of the kidney beyond cysteine antioxidant properties, highlighting the relevance of cysteine and its renal metabolism in the control of cysteine excess in the body as a pivotal source of metabolites to kidney biomass and bioenergetics and a promoter of adaptive responses to stressors. This view might translate into novel perspectives on the mechanisms of kidney function and blood pressure regulation and on clinical implications of the cysteine-related thiolome as a tool in precision medicine.publishersversionpublishe

Glutamine and cystine-enriched diets modulate aquaporins gene expression in the small intestine of piglets

Research ArticleThe regulation of glycerol permeability in the gastrointestinal tract is crucial to control fat deposition, lipolysis and gluconeogenesis. Knowing that the amino acid glutamine is a physiological regulator of gluconeogenesis, whereas cystine promotes adiposity, herein we investigated the effects of dietary supplementation with glutamine and cystine on the serum biochemical parameters of piglets fed on amino acid-enriched diets, as well as on the transcriptional profile of membrane water and glycerol channels aquaporins (AQPs) in the ileum portion of the small intestine and its impact on intestinal permeability. Twenty male piglets with an initial body weight of 8.8 ± 0.89 kg were allocated to four dietary treatments (n = 5) and received, during a four week-period, a basal diet without supplementation (control) or supplemented with 8 kg/ton of glutamine (Gln), cystine (Cys) or the combination of the two amino acids in equal proportions (Gln + Cys). Most biochemical parameters were found improved in piglets fed Gln and Cys diet. mRNA levels of AQP3 were found predominant over the others. Both amino acids, individually or combined, were responsible for a consistent downregulation of AQP1, AQP7 and AQP10, without impacting on water permeability. Conversely, Cys enriched diet upregulated AQP3 enhancing basolateral membranes glycerol permeability and downregulating glycerol kinase (GK) of intestinal cells. Altogether, our data reveal that amino acids dietary supplementation can modulate intestinal AQPs expression and unveil AQP3 as a promising target for adipogenesis regulationinfo:eu-repo/semantics/publishedVersio