Identification of an H-Ras nanocluster disrupting peptide.

Hyperactive Ras signalling is found in most cancers. Ras proteins are only active in membrane nanoclusters, which are therefore potential drug targets. We previously showed that the nanocluster scaffold galectin-1 (Gal1) enhances H-Ras nanoclustering via direct interaction with the Ras binding domain (RBD) of Raf. Here, we establish that the B-Raf preference of Gal1 emerges from the divergence of the Raf RBDs at their proposed Gal1-binding interface. We then identify the L5UR peptide, which disrupts this interaction by binding with low micromolar affinity to the B- and C-Raf-RBDs. Its 23-mer core fragment is sufficient to interfere with H-Ras nanoclustering, modulate Ras-signalling and moderately reduce cell viability. These latter two phenotypic effects may also emerge from the ability of L5UR to broadly engage with several RBD- and RA-domain containing Ras interactors. The L5UR-peptide core fragment is a starting point for the development of more specific reagents against Ras-nanoclustering and -interactors.

An Improved PDE6D Inhibitor Combines with Sildenafil To Inhibit KRAS Mutant Cancer Cell Growth.

The trafficking chaperone PDE6D (or PDEδ) was proposed as a surrogate target for K-Ras, leading to the development of a series of inhibitors that block its prenyl binding pocket. These inhibitors suffered from low solubility and suspected off-target effects, preventing their clinical development. Here, we developed a highly soluble, low nanomolar PDE6D inhibitor (PDE6Di), Deltaflexin3, which has the lowest off-target activity as compared to three prominent reference compounds. Deltaflexin3 reduces Ras signaling and selectively decreases the growth of KRAS mutant and PDE6D-dependent cancer cells. We further show that PKG2-mediated phosphorylation of Ser181 lowers K-Ras binding to PDE6D. Thus, Deltaflexin3 combines with the approved PKG2 activator Sildenafil to more potently inhibit PDE6D/K-Ras binding, cancer cell proliferation, and microtumor growth. As observed previously, inhibition of Ras trafficking, signaling, and cancer cell proliferation remained overall modest. Our results suggest reevaluating PDE6D as a K-Ras surrogate target in cancer.

K-Ras Binds Calmodulin-Related Centrin1 with Potential Implications for K-Ras Driven Cancer Cell Stemness.

Recent data suggest that K-Ras4B (hereafter K-Ras) can drive cancer cell stemness via calmodulin (CaM)-dependent, non-canonical Wnt-signalling. Here we examined whether another Ca2+-binding protein, the CaM-related centrin1, binds to K-Ras and could mediate some K-Ras functions that were previously ascribed to CaM. While CaM and centrin1 appear to distinguish between peptides that were derived from their classical targets, they both bind to K-Ras in cells. Cellular BRET- and immunoprecipitation data suggest that CaM engages more with K-Ras than centrin1 and that the interaction with the C-terminal membrane anchor of K-Ras is sufficient for this. Surprisingly, binding of neither K-Ras nor its membrane anchor alone to CaM or centrin1 is sensitive to inhibition of prenylation. In support of an involvement of the G-domain of K-Ras in cellular complexes with these Ca2+-binding proteins, we find that oncogenic K-RasG12V displays increased engagement with both CaM and centrin1. This is abrogated by addition of the D38A effector-site mutation, suggesting that K-RasG12V is held together with CaM or centrin1 in complexes with effectors. When treated with CaM inhibitors, the BRET-interaction of K-RasG12V with centrin1 was also disrupted in the low micromolar range, comparable to that with CaM. While CaM predominates in regulating functional membrane anchorage of K-Ras, it has a very similar co-distribution with centrin1 on mitotic organelles. Given these results, a significant overlap of the CaM- and centrin1-dependent functions of K-Ras is suggested.

Detection of Ras nanoclustering-dependent homo-FRET using fluorescence anisotropy measurements.

The small GTPase Ras is frequently mutated in cancer and a driver of tumorigenesis. The recent years have shown great progress in drug-targeting Ras and understanding how it operates on the plasma membrane. We now know that Ras is non-randomly organized into proteo-lipid complexes on the membrane, called nanoclusters. Nanoclusters contain only a few Ras proteins and are necessary for the recruitment of downstream effectors, such as Raf. If tagged with fluorescent proteins, the dense packing of Ras in nanoclusters can be analyzed by Förster/ fluorescence resonance energy transfer (FRET). Loss of FRET can therefore report on decreased nanoclustering and any process upstream of it, such as Ras lipid modifications and correct trafficking. Thus, cellular FRET screens employing Ras-derived fluorescence biosensors are potentially powerful tools to discover chemical or genetic modulators of functional Ras membrane organization. Here we implement fluorescence anisotropy-based homo-FRET measurements of Ras-derived constructs labelled with only one fluorescent protein on a confocal microscope and a fluorescence plate reader. We show that homo-FRET of both H-Ras- and K-Ras-derived constructs can sensitively report on Ras-lipidation and -trafficking inhibitors, as well as on genetic perturbations of proteins regulating membrane anchorage. By exploiting the switch I/II-binding Ras-dimerizing compound BI-2852, this assay is also suitable to report on the engagement of the K-Ras switch II pocket by small molecules such as AMG 510. Given that homo-FRET only requires one fluorescent protein tagged Ras construct, this approach has significant advantages to create Ras-nanoclustering FRET-biosensor reporter cell lines, as compared to the more common hetero-FRET approaches.

30-Day Clinical Outcomes of a Self-Expanding Transcatheter Aortic Valve: The International PORTICO NG Study.

BACKGROUND: The self-expanding, intra-annular Navitor (Abbott Structural Heart) valve includes an outer cuff to reduce paravalvular leak (PVL) and large stent cells for future coronary access. OBJECTIVES: The purpose of the PORTICO NG (Evaluation of the Portico NG [Next Generation] Transcatheter Aortic Valve in High and Extreme Risk Patients With Symptomatic Severe Aortic Stenosis) study is to evaluate the safety and effectiveness of the Navitor valve in patients with symptomatic, severe aortic stenosis who are at high or extreme surgical risk. METHODS: PORTICO NG is a prospective, multicenter, global study with follow-up at 30 days, 1 year, and annually through 5 years. The primary endpoints are all-cause mortality and moderate or greater PVL at 30 days. Valve Academic Research Consortium-2 events and valve performance are assessed by an independent clinical events committee and echocardiographic core laboratory. RESULTS: A total of 260 subjects were treated at 26 clinical sites across Europe, Australia, and the United States between September 2019 and August 2022. The mean age was 83.4 ± 5.4 years, 57.3% were female, and the average Society of Thoracic Surgeons score was 3.9% ± 2.1%. At 30 days, the rate of all-cause mortality was 1.9%, and no subjects had moderate or greater PVL. The rate of disabling stroke was 1.9%, life-threatening bleeding was 3.8%, stage 3 acute kidney injury was 0.8%, major vascular complications were 4.2%, and new permanent pacemaker implantation was 19.0%. Hemodynamic performance included a mean gradient of 7.4 ± 3.5 mm Hg and an effective orifice area of 2.00 ± 0.47 cm2. CONCLUSIONS: The Navitor valve is safe and effective for the treatment of subjects with severe aortic stenosis who are at high or greater risk for surgery, which is supported by low rates of adverse events and PVL. (Evaluation of the Portico NG [Next Generation] Transcatheter Aortic Valve in High and Extreme Risk Patients With Symptomatic Severe Aortic Stenosis [PORTICO NG]; NCT04011722).

Potential of phenothiazines to synergistically block calmodulin and reactivate PP2A in cancer cells.

Phenothiazines (PTZ) were developed as inhibitors of monoamine neurotransmitter receptors, notably dopamine receptors. Because of this activity they have been used for decades as antipsychotic drugs. In addition, they possess significant anti-cancer properties and several attempts for their repurposing were made. However, their incompletely understood polypharmacology is challenging. Here we examined the potential of the PTZ fluphenazine (Flu) and its mustard derivative (Flu-M) to synergistically act on two cancer associated targets, calmodulin (CaM) and the tumor suppressor protein phosphatase 2A (PP2A). Both proteins are known to modulate the Ras- and MAPK-pathway, cell viability and features of cancer cell stemness. Consistently, we show that the combination of a CaM inhibitor and the PP2A activator DT-061 synergistically inhibited the 3D-spheroid formation of MDA-MB-231 (K-Ras-G13D), NCI-H358 (K-Ras-G12C) and A375 (B-raf-V600E) cancer cells, and increased apoptosis in MDA-MB-231. We reasoned that these activities remain combined in PTZ, which were the starting point for PP2A activator development, while several PTZ are known CaM inhibitors. We show that both Flu and Flu-M retained CaM inhibitory activity in vitro and in cells, with a higher potency of the mustard derivative in cells. In line with the CaM dependence of Ras plasma membrane organization, the mustard derivative potently reduced the functional membrane organization of oncogenic Ras, while DT-061 had a negligible effect. Like DT-061, both PTZ potently decreased c-MYC levels, a hallmark of PP2A activation. Benchmarking against the KRAS-G12C specific inhibitor AMG-510 in MIA PaCa-2 cells revealed a higher potency of Flu-M than combinations of DT-061 and a CaM inhibitor on MAPK-output and a strong effect on cell proliferation. While our study is limited, our results suggest that improved PTZ derivatives that retain both, their CaM inhibitory and PP2A activating properties, but have lost their neurological side-effects, may be interesting to pursue further as anti-cancer agents.

Final 3-year clinical outcomes following transcatheter aortic valve implantation with a supra-annular self-expanding repositionable valve in a real-world setting: Results from the multicenter FORWARD study.

OBJECTIVES: The Evolut R FORWARD study confirmed safety and effectivenesss of the Evolut R THV in routine clinical practice out to 1 year. Herein, we report the final 3-year clinical follow up of the FORWARD study. BACKGROUND: Transcatheter aortic valve replacement (TAVR) is a proven alternative to surgery in elderly patients with symptomatic severe aortic stenosis. Long-term clinical outcome data with the Evolut R platform are scarce. METHODS: FORWARD is a prospective multicenter observational study that evaluated the Evolut R system in routine clinical practice at 53 centres. Eligible patients had symptomatic native aortic valve stenosis or failed surgical aortic bioprosthesis and elevated operative risk per Heart-Team assessment. TAVR was attempted in 1039 patients. RESULTS: Mean age was 81.8 ± 6.2 years, 64.9% were women, STS score was 5.5 ± 4.5% and 34.2% were frail. Rates of all-cause mortality and disabling stroke were 24.8% and 4.8% at 3 years. Early need for a new pacemaker implantation after TAVR (all-cause mortality: with new PPI; 21.0% vs. without; 22.8%, p = 0.55) and the presence of > trace paravalvular regurgitation (all-cause mortality: no or trace; 22.0% vs. ≥ mild; 25.5%, p = 0.29) did not affect survival. Between 1 and 3 years incidence rates of valve related intervention, endocarditis and clinically relevant valve thrombosis were low. CONCLUSIONS: The Evolut R valve maintained a favorable safety profile through 3 years in routine clinical practice. Rates of transcatheter heart valve-related adverse events were low.

A Covalent Calmodulin Inhibitor as a Tool to Study Cellular Mechanisms of K-Ras-Driven Stemness.

Recently, the highly mutated oncoprotein K-Ras4B (hereafter K-Ras) was shown to drive cancer cell stemness in conjunction with calmodulin (CaM). We previously showed that the covalent CaM inhibitor ophiobolin A (OphA) can potently inhibit K-Ras stemness activity. However, OphA, a fungus-derived natural product, exhibits an unspecific, broad toxicity across all phyla. Here we identified a less toxic, functional analog of OphA that can efficiently inactivate CaM by covalent inhibition. We analyzed a small series of benzazulenones, which bear some structural similarity to OphA and can be synthesized in only six steps. We identified the formyl aminobenzazulenone 1, here named Calmirasone1, as a novel and potent covalent CaM inhibitor. Calmirasone1 has a 4-fold increased affinity for CaM as compared to OphA and was active against K-Ras in cells within minutes, as compared to hours required by OphA. Calmirasone1 displayed a 2.5-4.5-fold higher selectivity for KRAS over BRAF mutant 3D spheroid growth than OphA, suggesting improved relative on-target activity. Importantly, Calmirasone1 has a 40-260-fold lower unspecific toxic effect on HRAS mutant cells, while it reaches almost 50% of the activity of novel K-RasG12C specific inhibitors in 3D spheroid assays. Our results suggest that Calmirasone1 can serve as a new tool compound to further investigate the cancer cell biology of the K-Ras and CaM associated stemness activities.

Open transcatheter valve implantation for mitral annular calcification: One-year outcomes.

BACKGROUND: Transcatheter mitral valve implantation (TMVI) for native mitral valve pathology with severe mitral annular calcification has emerged as an alternative treatment option to conventional mitral valve surgery. The objective of this study was to evaluate patients who were referred for TMVI with severe mitral annular calcification and their procedural outcomes. METHODS: Retrospective analysis of patients from 2017 to 2020 referred for TMVI was carried out. Demographic characteristic details; surgical strategy; perioperative complications; and hospital stay, including 30-day and 1-year mortality, were analyzed. RESULTS: Eleven patients were referred for consideration of TMVI. The 8 patients who underwent TMVI had a median age of 74 years (range, 57-80 years), the median Society of Thoracic Surgeons score was 4.6 (range, 2.4-10.9), and European System for Cardiac Operative Risk Evaluation II score was 5.2% (2%-10.1%). The median cardiopulmonary bypass time and crossclamp times were 170 minutes (range, 150-248 minutes) and 152 minutes (range, 118-214 minutes), respectively. The median hospital stay was 29 days (range, 2-40 days). Thirty-day in hospital mortality was 12%, whereas 1-year mortality was 25%. There was symptomatic improvement with downgrade of New York Heart Association functional class from III or IV to I or II. The 3 patients who were turned down had a median age of 73 years, median Society of Thoracic Surgeons score was 13.4, and median European System for Cardiac Operative Risk Evaluation II score was 5.72%. They were alive at 12 months follow-up from the date of surgical assessment; however, all with New York Heart Association functional class III or IV symptoms. CONCLUSIONS: We describe a series demonstrating the technical consideration and capability of transatrial TMVI to treat mitral annular calcification and native mitral valve disease. Our results are favorable when compared with TMVI global registry data for transseptal or transapical approach.

PDE6D Inhibitors with a New Design Principle Selectively Block K-Ras Activity.

The trafficking chaperone PDE6D (also referred to as PDEδ) has been nominated as a surrogate target for K-Ras4B (hereafter K-Ras). Arl2-assisted unloading of K-Ras from PDE6D in the perinuclear area is significant for correct K-Ras localization and therefore activity. However, the unloading mechanism also leads to the undesired ejection of PDE6D inhibitors. To counteract ejection, others have recently optimized inhibitors for picomolar affinities; however, cell penetration generally seems to remain an issue. To increase resilience against ejection, we engineered a "chemical spring" into prenyl-binding pocket inhibitors of PDE6D. Furthermore, cell penetration was improved by attaching a cell-penetration group, allowing us to arrive at micromolar in cellulo potencies in the first generation. Our model compounds, Deltaflexin-1 and -2, selectively disrupt K-Ras, but not H-Ras membrane organization. This selectivity profile is reflected in the antiproliferative activity on colorectal and breast cancer cells, as well as the ability to block stemness traits of lung and breast cancer cells. While our current model compounds still have a low in vitro potency, we expect that our modular and simple inhibitor redesign could significantly advance the development of pharmacologically more potent compounds against PDE6D and related targets, such as UNC119 in the future.

Medium-Throughput Detection of Hsp90/Cdc37 Protein-Protein Interaction Inhibitors Using a Split Renilla Luciferase-Based Assay.

The protein-folding chaperone Hsp90 enables the maturation and stability of various oncogenic signaling proteins and is thus pursued as a cancer drug target. Folding in particular of protein kinases is assisted by the co-chaperone Cdc37. Several inhibitors against the Hsp90 ATP-binding site have been developed. However, they displayed significant toxicity in clinical trials. By contrast, the natural product conglobatin A has an exceptionally low toxicity in mice. It targets the protein-protein interface (PPI) of Hsp90 and Cdc37, suggesting that interface inhibitors have an interesting drug development potential. In order to identify inhibitors of the Hsp90/Cdc37 PPI, we have established a mammalian cell lysate-based, medium-throughput amenable split Renilla luciferase assay. This assay employs N-terminal and C-terminal fragments of Renilla luciferase fused to full-length human Hsp90 and Cdc37, respectively. We expect that our assay will allow for the identification of novel Hsp90/Cdc37 interaction inhibitors. Such tool compounds will help to evaluate whether the toxicity profile of Hsp90/Cdc37 PPI inhibitors is in general more favorable than that of ATP-competitive Hsp90 inhibitors. Further development of such tool compounds may lead to new classes of Hsp90 inhibitors with applications in cancer and other diseases.

High-throughput amenable fluorescence-assays to screen for calmodulin-inhibitors.

The KRAS gene is highly mutated in human cancers and the focus of current Ras drug development efforts. Recently the interface between the C-terminus of K-Ras and calmodulin (CaM) was proposed as a target site to block K-Ras driven cancer cell stemness. We therefore aimed at developing a high-throughput amenable screening assay to identify novel CaM-inhibitors as potential K-Ras stemness-signaling disruptors. A modulated time-resolved Förster resonance energy transfer (mTR-FRET)-assay was developed and benchmarked against an identically designed fluorescence anisotropy (FA)-assay. In both assays, two CaM-binding peptides were labeled with Eu(III)-chelate or fluorescein and used as single-label reporter probes that were displaced from CaM upon competitor binding. Thus, peptidic and small molecule competitors with nanomolar to micromolar affinities to CaM could be detected, including a peptide that was derived from the C-terminus of K-Ras. In order to detect CaM-residue specific covalent inhibitors, a cell lysate-based Förster resonance energy transfer (FRET)-assay was furthermore established. This assay enabled us to measure the slow, residue-specific, covalent inhibition by ophiobolin A in the presence of other endogenous proteins. In conclusion, we have developed a panel of fluorescence-assays that allows identification of conventional and covalent CaM-inhibitors as potential disruptors of K-Ras driven cancer cell stemness.

The role of surgical transcatheter valve implantation for the treatment of severe mitral annular calcification.

With a rise in the aging population, mitral annular calcification is increasingly encountered with an incidence of 10% in over 70 years old. This with increasing patient comorbidities presents a technical challenge due to the risk of atrioventricular disruption which is associated with high operative mortality of up to 75%. We describe two cases of severe mitral disease with marked annular calcification successfully treated with a balloon expandable transcatheter valve which was deployed on cardiopulmonary bypass via a trans-atrial approach.

Incidence of new-onset left bundle branch block and predictors of new permanent pacemaker following transcatheter aortic valve replacement with the Portico™ valve.

OBJECTIVES: To examine the incidence and timing of new-onset left bundle branch block (LBBB) and new permanent pacemaker implantation (PPI) in patients undergoing transcatheter aortic valve implantation (TAVI) using the repositionable, self-expanding Portico™ TAVI system (St. Jude Medical, St Paul, MN, USA). Clinical impact and periprocedural factors associated with new PPI were also assessed. METHODS: A total of 198 high-risk patients without pre-existing pacemaker [83.1 ± 4.7 years, 77.3% women, mean Society of Thoracic Surgeons (STS) 5.8%] from the Pre-CE Mark Portico TAVI system study were prospectively analysed. Twelve-lead electrocardiographic and echocardiographic data were collected prior to, during and after the procedure. Clinical follow-up was performed at 1 year. RESULTS: Transfemoral implantation of the Portico valve was associated with a new PPI rate of 15.2% at 30 days and 16.7% at 1 year. Overall, 53 of the 187 patients without pre-existing LBBB developed new-onset LBBB at 1 year (28.3%); 23 occurred during the procedure. At 30 days, new-onset LBBB spontaneously resolved in 61.0% of patients. New-onset LBBB post-TAVI was not associated with new PPI (P = 0.64); 8 of the 53 patients required new PPI. Multivariable regression analyses revealed pre-existing right bundle branch block (P = 0.004) and aortic annulus diameter (P = 0.001) as independent predictors of new PPI. New PPI at discharge (n = 29) was not associated with increased freedom from all-cause (odds ratio 92.7%, 95% confidence interval 73.7-98.1%; P = 0.49) and cardiovascular (odds ratio 96.6%, 95% confidence interval 77.9-99.5%; P = 0.47) mortality at 1 year. CONCLUSIONS: The Portico TAVI system demonstrated an acceptable rate of new PPI at 1 year without increased mortality risk to patients. New-onset LBBB was common during the procedure, with the majority of events spontaneously resolving by 30 days. No intraprocedural factors were shown to independently predict new PPI. Clinical trial registration number: NCT01493284.

Repositionable percutaneous aortic valve implantation with the LOTUS valve: 30-day and 1-year outcomes in 250 high-risk surgical patients.

AIMS: The REPRISE IIE trial aimed to evaluate outcomes following transcatheter aortic valve implantation of the fully repositionable and retrievable LOTUS valve with a unique seal designed to minimise paravalvular leak (PVL). METHODS AND RESULTS: This prospective, multicentre study enrolled 250 patients with severe aortic stenosis considered high-risk for surgery by a multidisciplinary Heart Team. An independent clinical events committee adjudicated events per Valve Academic Research Consortium criteria. Mean age was 84 years; 77% were in NYHA Class III/IV. LOTUS valve implantation produced significant haemodynamic improvements at one year without valve embolisation, ectopic valve deployment, or additional valve implantation. Primary endpoints were met as the 30-day mortality rate in the extended cohort (4.4%, N=250), and mean valve gradient in the main cohort (11.5±5.2 mmHg, N=120) were below (p<0.001) their predefined performance objectives. At 30 days, disabling stroke was 2.8% and new pacemaker implantation was 28.9% in all patients and 32.0% in pacemaker-naïve patients. By one year, all-cause mortality was 11.6%, disabling stroke was 3.6%, 95% of patients alive were in NYHA Class I/II, and there was no core laboratory-adjudicated moderate/severe PVL. CONCLUSIONS: LOTUS valve implantation produced good valve haemodynamics, minimal PVL, sustained significant improvement in functional status, and good clinical outcomes one year post implant.

Matched Comparison of Self-Expanding Transcatheter Heart Valves for the Treatment of Failed Aortic Surgical Bioprosthesis: Insights From the Valve-in-Valve International Data Registry (VIVID).

BACKGROUND: Transcatheter valve-in-valve implantation is an established therapy for high-risk patients with failed surgical aortic bioprosthesis. There are limited data comparing outcomes of valve-in-valve implantation using different transcatheter heart valves (THV). METHODS AND RESULTS: Patients included in the Valve-in-Valve International Data registry (VIVID) and treated with self-expanding THV devices were analyzed using centralized core laboratory blinded to clinical events. St. Jude Medical Portico versus Medtronic CoreValve were compared in a 1:2 fashion after propensity score matching. A total of 162 patients, Portico- (n=54) and CoreValve- (n=108) based valve-in-valve procedures comprised the study population with no significant difference in baseline characteristics (age, 79±8.2 years; 60% women; mean STS [Society of Thoracic Surgery] score 8.1±5.5%). Postimplantation, CoreValve was associated with a larger effective orifice area (1.67 versus 1.31 cm2; P=0.001), lower mean gradient (14±7.5 versus 17±7.5 mm Hg; P=0.02), and lower core laboratory-adjudicated moderate-to-severe aortic insufficiency (4.2% versus 13.7%; P=0.04), compared with Portico. Procedural complications including THV malpositioning, second THV requirement, or coronary obstruction were not significantly different between the 2 groups. Survival and stroke rates at 30 days were similar, but overall mortality at 1 year was higher among patients treated with Portico compared with CoreValve (22.6% versus 9.1%; P=0.03). CONCLUSIONS: In this first matched comparison of THVs for valve-in-valve implantations, Portico and CoreValve demonstrated differences in postprocedural hemodynamics and long-term clinical outcomes. Although this could be related to THV design characteristics, the impact of other procedural factors cannot be excluded and require further evaluation.

Bifunctional Ligands for Inhibition of Tight-Binding Protein-Protein Interactions.

The acknowledged potential of small-molecule therapeutics targeting disease-related protein-protein interactions (PPIs) has promoted active research in this field. The strategy of using small molecule inhibitors (SMIs) to fight strong (tight-binding) PPIs tends to fall short due to the flat and wide interfaces of PPIs. Here we propose a biligand approach for disruption of strong PPIs. The potential of this approach was realized for disruption of the tight-binding (KD = 100 pM) tetrameric holoenzyme of cAMP-dependent protein kinase (PKA). Supported by X-ray analysis of cocrystals, bifunctional inhibitors (ARC-inhibitors) were constructed that simultaneously associated with both the ATP-pocket and the PPI interface area of the catalytic subunit of PKA (PKAc). Bifunctional inhibitor ARC-1411, possessing a KD value of 3 pM toward PKAc, induced the dissociation of the PKA holoenzyme with a low-nanomolar IC50, whereas the ATP-competitive inhibitor H89 bound to the PKA holoenzyme without disruption of the protein tetramer.

Phosphorylation of Notch1 by Pim kinases promotes oncogenic signaling in breast and prostate cancer cells.

Tumorigenesis is a multistep process involving co-operation between several deregulated oncoproteins. In this study, we unravel previously unrecognized interactions and crosstalk between Pim kinases and the Notch signaling pathway, with implications for both breast and prostate cancer. We identify Notch1 and Notch3, but not Notch2, as novel Pim substrates and demonstrate that for Notch1, the serine residue 2152 is phosphorylated by all three Pim family kinases. This target site is located in the second nuclear localization sequence (NLS) of the Notch1 intracellular domain (N1ICD), and is shown to be important for both nuclear localization and transcriptional activity of N1ICD. Phosphorylation-dependent stimulation of Notch1 signaling promotes migration of prostate cancer cells, balances glucose metabolism in breast cancer cells, and supports in vivo growth of both types of cancer cells on chick embryo chorioallantoic membranes. Furthermore, Pim-induced growth of orthotopic prostate xenografts in mice is associated with enhanced nuclear Notch1 activity. Finally, simultaneous inhibition of Pim and Notch abrogates the cellular responses more efficiently than individual treatments, opening up new vistas for combinatorial cancer therapy.

1-Year Outcomes With the Fully Repositionable and Retrievable Lotus Transcatheter Aortic Replacement Valve in 120 High-Risk Surgical Patients With Severe Aortic Stenosis: Results of the REPRISE II Study.

OBJECTIVES: This analysis presents the first report of 1-year outcomes of the 120 patients enrolled in the REPRISE II (Repositionable Percutaneous Placement of Stenotic Aortic Valve Through Implantation of Lotus Valve System-Evaluation of Safety and Performance) study. BACKGROUND: The fully repositionable and retrievable Lotus Valve (Boston Scientific, Marlborough, Massachusetts) was designed to facilitate accurate positioning, early valve function, and hemodynamic stability during deployment and to minimize paravalvular regurgitation in patients undergoing transcatheter aortic valve replacement. METHODS: The study enrolled 120 symptomatic patients 70 years of age or older at 14 centers in Australia and Europe. Patients had severe calcific aortic stenosis and were deemed to be at high or extreme risk of surgery based on assessment by the heart team. RESULTS: The mean age was 84.4 ± 5.3 years, 57% (68 of 120) of patients were women, and the mean Society of Thoracic Surgeons score was 7.1 ± 4.6. The mean baseline aortic valve area was 0.7 ± 0.2 cm(2), and the mean transvalvular pressure gradient was 46.4 ± 15.0 mm Hg. All patients were successfully implanted with a Lotus Valve, and 1-year clinical follow-up was available for 99.2% (119 of 120 of patients). The mean 1-year transvalvular aortic pressure gradient was 12.6 ± 5.7 mm Hg, and the mean valve area was 1.7 ± 0.5 cm(2). A total of 88.6% patients had no or trivial paravalvular aortic regurgitation at 1 year by independent core lab adjudication, and 97.1% of patients were New York Heart Association functional class I or II. At 1 year, the all-cause mortality rate was 10.9% (13 of 119 patients), disabling stroke rate was 3.4% (4 of 119 patients), disabling bleeding rate was 5.9% (7 of 119 patients), with no repeat procedures for valve-related dysfunction. A total of 31.9% (38 of 119 patients) underwent new permanent pacemaker implantation at 1 year. CONCLUSIONS: At 1 year of follow-up, the Lotus Valve demonstrated excellent valve hemodynamics, no moderate or severe paravalvular regurgitation, and significant and sustained improvement in New York Heart Association functional class status, with good clinical outcomes. (Repositionable Percutaneous Placement of Stenotic Aortic Valve Through Implantation of Lotus Valve System-Evaluation of Safety and Performance [REPRISE II]; NCT01627691).

Combining chemical and genetic approaches for development of responsive FRET-based sensor systems for protein kinases.

Chemical and genetic approaches were combined for the development of responsive FRET-based sensor systems for protein kinases, using PIM2 as the model kinase. Fusions of PIM2 and a red fluorescent protein, TagRFP were expressed in mammalian cells and small-molecule ARC-Lum photoluminescent probes possessing different phosphorescent and fluorescent properties were constructed. Based on a variety of Förster-type resonant energy transfer (FRET) mechanisms (including intermolecular or intramolecular energy transfer and transfer between singlet-singlet or triplet-singlet electronic states of interacting luminophores) of the probe and that of the fluorescently tagged PIM2, FRET-based sensor systems were constructed. The developed assays can be applied for analysis of PIM2 in biological samples and screening and characterization of PIM2 inhibitors in cell lysates. In screening studies sub-micromolar affinity of a d-arginine-rich peptide, nona(d-arginine) amide [(d-Arg)9-NH2], towards PIM2 was discovered that points to possible specific effect of this widely used transport peptide to cellular protein phosphorylation balance.