NACA and LRP6 Are Part of a Common Genetic Pathway Necessary for Full Anabolic Response to Intermittent PTH

PTH induces phosphorylation of the transcriptional coregulator NACA on serine 99 through Gαs and PKA. This leads to nuclear translocation of NACA and expression of the target gene Lrp6, encoding a coreceptor of the PTH receptor (PTH1R) necessary for full anabolic response to intermittent PTH (iPTH) treatment. We hypothesized that maintaining enough functional PTH1R/LRP6 coreceptor complexes at the plasma membrane through NACA-dependent Lrp6 transcription is important to ensure maximal response to iPTH. To test this model, we generated compound heterozygous mice in which one allele each of Naca and Lrp6 is inactivated in osteoblasts and osteocytes, using a knock-in strain with a Naca99 Ser-to-Ala mutation and an Lrp6 floxed strain (test genotype: Naca99S/A; Lrp6+/fl;OCN-Cre). Four-month-old females were injected with vehicle or 100 μg/kg PTH(1-34) once daily, 5 days a week for 4 weeks. Control mice showed significant increases in vertebral trabecular bone mass and biomechanical properties that were abolished in compound heterozygotes. Lrp6 expression was reduced in compound heterozygotes vs. controls. The iPTH treatment increased Alpl and Col1a1 mRNA levels in the control but not in the test group. These results confirm that NACA and LRP6 form part of a common genetic pathway that is necessary for the full anabolic effect of iPTH.

Integrated exposure–response analysis of efficacy and safety of lurbinectedin to support the dose regimen in small-cell lung cancer

Purpose These exposure–response (E–R) analyses integrated lurbinectedin effects on key efficacy and safety variables in relapsed SCLC to determine the adequacy of the dose regimen of 3.2 mg/m2 1-h intravenous infusion every 3 weeks (q3wk). Methods Logistic models and Cox regression analyses were applied to correlate lurbinectedin exposure metrics (AUCtot and AUCu) with efficacy and safety endpoints: objective response rate (ORR) and overall survival (OS) in SCLC patients (n = 99) treated in study B-005 with 3.2 mg/m2 q3wk, and incidence of grade 4 (G4) neutropenia and grade 3–4 (G ≥ 3) thrombocytopenia in a pool of cancer patients from single-agent phase I to III studies (n = 692) treated at a wide range of doses. A clinical utility index was used to assess the appropriateness of the selected dose. Results Effect of lurbinectedin AUCu on ORR best fitted to a sigmoid-maximal response (Emax) logistic model, where Emax was dependent on chemotherapy-free interval (CTFI). Cox regression analysis with OS found relationships with both CTFI and AUCu. An Emax logistic model for G4 neutropenia and a linear logistic model for G ≥ 3 thrombocytopenia, which retained platelets and albumin at baseline and body surface area, best fitted to AUCtot and AUCu. AUCu between approximately 1000 and 1700 ng·h/L provided the best benefit/risk ratio, and the dose of 3.2 mg/m2 provided median AUCu of 1400 ng·h/L, thus maximizing the proportion of patients within that lurbinectedin target exposure range. Conclusions The relationships evidenced in this integrated E–R analysis support a favorable benefit-risk profile for lurbinectedin 3.2 mg/m2 q3wk. Trial registration Clinicaltrials.gov: NCT02454972; registered May 27, 2015.

Real-World Experience of Vismodegib in Advanced Basal Cell Carcinoma at a Canadian Cancer Center

Background Vismodegib is a novel Hedgehog pathway inhibitor that has revolutionized the treatment of patients with advanced basal cell carcinoma (BCC) who are poor candidates for surgery or radiation. Few studies have explored the use of vismodegib to facilitate further surgery or radiotherapy, and the optimal treatment duration to balance outcomes with adverse effects. Objectives To characterize the disease response, progression, and recurrence outcomes of BCC patients, and to report the impact of subsequent therapies. Methods We performed a retrospective study of 46 adult patients with advanced basal cell carcinoma (aBCC), including both locally advanced (laBCC) and metastatic (mBCC) disease, treated with vismodegib at a single center from 2012 to 2019. Results Thirty-six had laBCC, and 10 had mBCC. Treatment was given over a mean of 21.9 months. Twenty-three (50%) had a complete response (CR), and 19 (41.3%) achieved partial response (PR). Median time to maximal response was 5.3 months. Eleven (23.9%) had resected disease at median 17.2 months, and 11 patients (23.9%) received radiotherapy. Thirty-two (69.6%) experienced progressive disease after achievement of CR or PR. Among 17 CR patients, who stopped treatment, 14 (82.3%) experienced subsequent relapse; 6 (85%) attained a repeat response. Twenty (43.5%) discontinued treatment at least once due to adverse effects. Conclusions With a response rate of 91%, London Regional Cancer Center’s (LRCP)’s experience with vismodegib supports its effectiveness in treatment of aBCC. Moreover, a significant number of patients treated with vismodegib became amenable to surgery or radiotherapy. Toxicity remained an important factor that limited treatment duration.

Efficient Ex Vivo Screening of Agents Targeting Thrombospondin1-Induced Vascular Dysfunction Using a Digital Multiwire Myograph System

Homeostasis of vascular tone is intricately and delicately maintained systemically and locally, by autonomic nerves and hormones in the blood and by intimal vasoactive substances, respectively. The balance can be acutely or chronically interrupted secondary to many alterations, especially under pathological conditions. Excessive matricellular glycoprotein thrombospondin 1 (TSP1) levels in circulation have been found to play an important role in ischemia-reperfusion injuries of different organs, by acutely suppressing vasorelaxation and chronically remodeling vascular bed. Our laboratory has been interested in identifying new drug moieties, which can selectively and effectively counteract TSP1-induced vascular dysfunction, in order to address associated clinical complications. Preliminary studies using computational docking and molecular models revealed potential drug candidates for further evaluation via vascular functional bioassay to prove the antagonism using an ex vivo vascular model. Herein, we described an efficient screening method for the identification of active drug candidates, by adapting a multiwire myograph system to perform a protocol with different treatments, in the presence of pathological levels of TSP1. We discussed the promising pharmacological evaluation results and suggested suitable modification for versatile applications. We also described the necessity of pre-determination of optimal resting tension to obtain the maximal response, if the experimental test model is different from those with determined optimal resting tension.

The role of biased calcium-sensing receptor signalling in urinary calcium excretion and kidney stone disease

Michelle Goldsworthy1,2, Asha Bayliss2, Anna Gluck2, Akira Wiberg3, Benjamin Turney1, DominicFurniss3, Rajesh Thakker2, Sarah Howles1,2 1Nuffield Department of Surgical Sciences, University of Oxford, United Kingdom.2Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, UnitedKingdom.3Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Universityof Oxford, United Kingdom. Nephrolithiasis is a major health burden with a poorly understood pathogenesis. We conducted a genome-wide association study in British and Japanese populations identifying twenty nephrolithiasis-associated loci. Mutations in the calcium-sensing receptor (CaSR) cause disorders of calcium homeostasis and five identified loci (DGKD, DGKH, WDR72, GPIC1 and BCR) were predicted to influence CaSR-signalling. In a validation population, we demonstrated that genotype at the DGKD-associated locus correlated with urinary calcium excretion but not serum calcium concentration. In vitro studies demonstrated that knockdown and overexpression of DGKD resulted in biased CaSR-signalling. Thus, treatment of CaSR-expressing HEK cells with DGKD-targeted siRNA (DGKD-KD), resulted in decreased MAPK responses to alterations in extracellular calcium concentration [Ca2+]e, as assessed by SRE-reporter and ERK-phosphorylation (pERK) assays, when compared to cells treated with scrambled siRNA (WT) but without alteration in intracellular calcium responses [Ca2+]i as assessed by NFAT-reporter and Fluo-4 calcium assays (SRE maximal response DGKD-KD =5.28 fold change vs. WT=7.20 p=0.0065, pERK maximal response DGKD-KD=24.77, vs. WT= 39.46 fold change, p=0.0056). Conversely, DGKD overexpression (DGKD-OE) increased MAPK responses but suppressed [Ca2+]i responses to alterations in [Ca2+]e (SRE maximal response DGKD-OE =14.13 fold change vs. WT=9.06 fold change, p=0.01; NFAT maximal response DGKD-OE=13.67 fold change vs WT=59.16 fold change, p=0.0001). Our results demonstrate that alterations in DGKD expression cause biased CaSR-signalling. This biased signalling may provide an explanation for the correlation of genotype at the DGKD-associated locus with urinary calcium excretion but not serum calcium concentration. Our findings suggest that biased CaSR-signalling may be a common cause of nephrolithiasis.

The role of biased calcium-sensing receptor signalling in urinary calcium excretion and kidney stone disease

Michelle Goldsworthy1,2, Asha Bayliss2, Anna Gluck2, Akira Wiberg3, Benjamin Turney1, DominicFurniss3, Rajesh Thakker2, Sarah Howles1,2 1Nuffield Department of Surgical Sciences, University of Oxford, United Kingdom.2Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, UnitedKingdom.3Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Universityof Oxford, United Kingdom. Nephrolithiasis is a major health burden with a poorly understood pathogenesis. We conducteda genome-wide association study in British and Japanese populations identifying twentynephrolithiasis-associated loci. Mutations in the calcium-sensing receptor (CaSR) causedisorders of calcium homeostasis and five identified loci (DGKD, DGKH, WDR72, GPIC1 and BCR)were predicted to influence CaSR-signalling. In a validation population, we demonstrated that genotype at the DGKD-associated locuscorrelated with urinary calcium excretion but not serum calcium concentration. In vitro studiesdemonstrated that knockdown and overexpression of DGKD resulted in biased CaSR-signalling.Thus, treatment of CaSR-expressing HEK cells with DGKD-targeted siRNA (DGKD-KD), resulted indecreased MAPK responses to alterations in extracellular calcium concentration [Ca2+]e, asassessed by SRE-reporter and ERK-phosphorylation (pERK) assays, when compared to cellstreated with scrambled siRNA (WT) but without alteration in intracellular calcium responses[Ca2+]i as assessed by NFAT-reporter and Fluo-4 calcium assays (SRE maximal response DGKD-KD=5.28 fold change vs. WT=7.20 p=0.0065, pERK maximal response DGKD-KD=24.77, vs. WT=39.46 fold change, p=0.0056). Conversely, DGKD overexpression (DGKD-OE) increased MAPKresponses but suppressed [Ca2+]i responses to alterations in [Ca2+]e (SRE maximal responseDGKD-OE =14.13 fold change vs. WT=9.06 fold change, p=0.01; NFAT maximal response DGKDOE=13.67 fold change vs WT=59.16 fold change, p=0.0001). Our results demonstrate that alterations in DGKD expression cause biased CaSR-signalling. Thisbiased signalling may provide an explanation for the correlation of genotype at the DGKDassociatedlocus with urinary calcium excretion but not serum calcium concentration. Ourfindings suggest that biased CaSR-signalling may be a common cause of nephrolithiasis.

Possible Cardio-protective Effect of Olive Oil in Experimentally Induced Hyperthyroidism in Rats

Background Hyperthyroidism is an endocrine disorder that causes both functional and structural changes in the cardiovascular system. Untreated hyperthyroidism and even persistent subclinical thyroid hyperactivity has been associated with the development of Heart failure by inducing atrial fibrillation, chronic hemodynamic overload, oxidative stress and activation of renin-angiotensin pathway. HF secondary to hyperthyroidism is a reversible cause of cardiomyopathy, which highlights the importance of its prompt diagnosis and treatment. Olive oil with its phenolic compounds are powerful antioxidant that may serve as potential therapeutic agents to reduce cardiovascular hazardous effect of hyperthyroidism and intake of virgin olive oil provides benefits on cardiovascular disease. Aim of the work The aim of the present study is to evaluate the possible cardio-protective effects of olive oil, as a natural antioxidant, in experimentally induced hyperthyroidism in rats. Also, to elucidate the underlying mechanism(s), if any, of its effects. Materials and Methods Animals used were 30 adult male albino rats, which were randomly allocated into three groups. Control group(n = 10): received intraperitoneal (i.p.) injection of the solvent of L-thyroxine daily for 4 consecutive weeks. Hyperthyroid group (n = 10): received i.p. injection of L-thyroxine 100μg/kg daily for 4 consecutive weeks. Olive oil-treated hyperthyroid group (n = 10): received i.p. L-Thyroxine as in group II. By the beginning of the third week, 1 ml/100 g B.W extra virgin olive oil was given daily by gavage for 2 weeks. At the end of the study, the overnight fasted rats were subjected to collection of retroorbital blood samples for determination of T3, T4, TSH serum levels. Rats were then weighed and anaesthetized with thiopental sodium (EIPICO, Egypt), IP (40 mg/kg B.W). Then, ECG was recorded. The heart was then subjected to In vitro study of isolated hearts perfused in langendorff preparation. Hearts chambers were then weighed. Apex of left ventricle was used in histopathological examination. Results The induction of hyperthyroidism was confirmed by T3 and T4 levels that were significantly increased, while TSH was significantly decreased in hyperthyroid group as well as olive oil-treated hyperthyroid group compared to control group. Compared to control group, both hyperthyroid and olive oil-treated hyperthyroid groups showed significant decrease in FBW, FBMI, BW% and BMI%. The absolute weights of RV, LV, WH, as well as, their relative weights RV/BW, LV/BW and WH/BW all were significantly increased. Compared to hyperthyroid group, olive oil-treated hyperthyroid group showed significant decrease in FBW as well as FBMI. The LV/BW and WH/BW were significantly increased. As regard ECG findings, HR, QRS duration and amplitude were significantly increased in both hyperthyroid and olive oil-treated hyperthyroid groups as compared to control rats. In the hyperthyroid group the PR interval was significantly shortened compared to control group, after olive oil-treatment PR interval increased significantly compared to hyperthyroid group, and became insignificant from control group. The baseline values in isolated perfused hearts study showed, significant increase in spontaneous beating rate in both hyperthyroid and olive oil-treated hyperthyroid groups as compared to control group. Hyperthyroid group showed non-significant decrease in TG/unit time and significant decrease in HRT compared to control group Olive oil-treated hyperthyroid group TG/unit time was non-significantly increased compared to control group and significantly increased compared to hyperthyroid group. HRT was the same as hyperthyroid group while. Isoprotrenol infusion showed early toxicity in hyperthyroid group indicated by reduced TG/unit time and HRT compared to control group. Olive oil-treated hyperthyroid group TG/unit time maximal response was significantly increased compared to hyperthyroid group, being non-significant from control group. The hematoxylin and eosin study of the left ventricular cardiac muscle, the hyperthyroid group showed apparent structural changes that were partially reversed by olive oil treatment. Conclusion Olive oil was able to impose partial improvement on cardiac systolic function at baseline condition, also, in response to the beta adrenergic agonist, isoproterenol, even though this improvement did not reach control levels.

Fetal Sex and Fetal Environment Interact to Alter Diameter, Myogenic Tone, and Contractile Response to Thromboxane Analog in Rat Umbilical Cord Vessels

Fetal growth needs adequate blood perfusion from both sides of the placenta, on the maternal side through the uterine vessels and on the fetal side through the umbilical cord. In a model of intrauterine growth restriction (IUGR) induced by reduced blood volume expansion, uterine artery remodeling was blunted. The aim of this study is to determine if IUGR and fetus sex alter the functional and mechanical parameters of umbilical cord blood vessels. Pregnant rats were given a low sodium (IUGR) or a control diet for the last 7 days of pregnancy. Umbilical arteries and veins from term (22 day) fetal rats were isolated and set-up in wire myographs. Myogenic tone, diameter, length tension curve and contractile response to thromboxane analog U46619 and serotonin (5-HT) were measured. In arteries from IUGR fetuses, myogenic tone was increased in both sexes while diameter was significantly greater only in male fetuses. In umbilical arteries collected from the control group, the maximal contraction to U46619 was lower in females than males. Compared to the control groups, the maximal response decreased in IUGR male arteries and increased in female ones, thus abolishing the sexual dimorphism observed in the control groups. Reduced contractile response to U46619 was observed in the IUGR vein of both sexes. No difference between groups was observed in response to 5HT in arteries. In conclusion, the change in parameters of the umbilical cord blood vessels in response to a mild insult seems to show adaptation that favors better exchange of deoxygenated and wasted blood from the fetus to the placenta with increased myogenic tone.

Dissecting the allosteric networks governing agonist efficacy and potency in G protein-coupled receptors

G protein-coupled receptors (GPCRs) translate binding of extracellular ligands into intracellular responses through conformational changes. Ligand properties are described by the maximum response (efficacy) and the agonist concentration at half-maximal response (potency). Integrating structural changes with pharmacological properties remains challenging and has not yet been performed at the resolution of individual amino acids. We use epinephrine and β2-adrenergic receptor as a model to integrate residue-level pharmacology data with intramolecular residue contact data describing receptor activation. This unveils the allosteric networks driving ligand efficacy and potency. We provide detailed insights into how structural rearrangements are linked to fundamental pharmacological properties at single-residue level in a receptor-ligand system. Our approach can be used to determine such pharmacological networks for any receptor-ligand complex.

Comparative vulnerability of PET radioligands to partial inhibition of P-glycoprotein at the blood-brain barrier: A criterion of choice?

Only partial deficiency/inhibition of P-glycoprotein (P-gp, ABCB1) function at the blood-brain barrier (BBB) is likely to occur in pathophysiological situations or drug-drug interactions. This raises questions regarding the sensitivity of available PET imaging probes to detect moderate changes in P-gp function at the living BBB. In vitro, the half-maximum inhibitory concentration (IC50) of the potent P-gp inhibitor tariquidar in P-gp-overexpressing cells was significantly different using either [11C]verapamil (44 nM), [11C] N-desmethyl-loperamide (19 nM) or [11C]metoclopramide (4 nM) as substrate probes. In vivo PET imaging in rats showed that the half-maximum inhibition of P-gp-mediated efflux of [11C]metoclopramide, achieved using 1 mg/kg tariquidar ( in vivo IC50 = 82 nM in plasma), increased brain exposure by 2.1-fold for [11C]metoclopramide (p < 0.05, n = 4) and 2.4-fold for [11C]verapamil (p < 0.05, n = 4), whereby cerebral uptake of the “avid” substrate [11C] N-desmethyl-loperamide was unaffected (p > 0.05, n = 4). This comparative study points to differences in the “vulnerability” to P-gp inhibition among radiolabeled substrates, which were apparently unrelated to their “avidity” (maximal response to P-gp inhibition). Herein, we advocate that partial inhibition of transporter function, in addition to complete inhibition, should be a primary criterion of evaluation regarding the sensitivity of radiolabeled substrates to detect moderate but physiologically-relevant changes in transporter function in vivo.