Structure-based discovery of orally efficient inhibitors via unique interactions with H-pocket of PDE8 for the treatment of vascular dementia

Our previous study demonstrated that phosphodiesterase 8 (PDE8) could work as a potential target for vascular dementia (VaD) using a chemical probe 3a. However, compound 3a is a chiral compound which was obtained by chiral resolution on HPLC, restricting its usage in clinic. Herein, a series of non-chiral 9-benzyl-2-chloro-adenine derivatives were discovered as novel PDE8 inhibitors. Lead 15 exhibited potent inhibitory activity against PDE8A (IC50 = 11 nmol/L), high selectivity over other PDEs, and remarkable drug-like properties (worthy to mention is that its bioavailability was up to 100%). Oral administration of 15 significantly improved the cAMP level of the right brain and exhibited dose-dependent effects on cognitive improvement in a VaD mouse model. Notably, the X-ray crystal structure of the PDE8A-15 complex showed that the potent affinity and high selectivity of 15 might come from the distinctive interactions with H-pocket including T-shaped π-π interactions with Phe785 as well as a unique H-bond network, which have never been observed in other PDE-inhibitor complex before, providing new strategies for the further rational design of novel selective inhibitors against PDE8.

Free energy perturbation (FEP)-guided scaffold hopping

Scaffold hopping refers to computer-aided screening for active compounds with different structures against the same receptor to enrich privileged scaffolds, which is a topic of high interest in organic and medicinal chemistry. However, most approaches cannot efficiently predict the potency level of candidates after scaffold hopping. Herein, we identified potent PDE5 inhibitors with a novel scaffold via a free energy perturbation (FEP)-guided scaffold-hopping strategy, and FEP shows great advantages to precisely predict the theoretical binding potencies ΔG FEP between ligands and their target, which were more consistent with the experimental binding potencies ΔG EXP (the mean absolute deviations | Δ G FEP - Δ G EXP |  < 2 kcal/mol) than those ΔG MM-PBSA or ΔG MM-GBSA predicted by the MM-PBSA or MM-GBSA method. Lead L12 had an IC50 of 8.7 nmol/L and exhibited a different binding pattern in its crystal structure with PDE5 from the famous starting drug tadalafil. Our work provides the first report via the FEP-guided scaffold hopping strategy for potent inhibitor discovery with a novel scaffold, implying that it will have a variety of future applications in rational molecular design and drug discovery.

A novel inhibitor of N 6-methyladenosine demethylase FTO induces mRNA methylation and shows anti-cancer activities

N 6-methyladenosine (m6A) modification is critical for mRNA splicing, nuclear export, stability and translation. Fat mass and obesity-associated protein (FTO), the first identified m6A demethylase, is critical for cancer progression. Herein, we developed small-molecule inhibitors of FTO by virtual screening, structural optimization, and bioassay. As a result, two FTO inhibitors namely 18077 and 18097 were identified, which can selectively inhibit demethylase activity of FTO. Specifically, 18097 bound to the active site of FTO and then inhibited cell cycle process and migration of cancer cells. In addition, 18097 reprogrammed the epi-transcriptome of breast cancer cells, particularly for genes related to P53 pathway. 18097 increased the abundance of m6A modification of suppressor of cytokine signaling 1 (SOCS1) mRNA, which recruited IGF2BP1 to increase mRNA stability of SOCS1 and subsequently activated the P53 signaling pathway. Further, 18097 suppressed cellular lipogenesis via downregulation of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and C/EBPβ. Animal studies confirmed that 18097 can significantly suppress in vivo growth and lung colonization of breast cancer cells. Collectively, we identified that FTO can work as a potential drug target and the small-molecule inhibitor 18097 can serve as a potential agent against breast cancer.

Medial parapatellar soft tissue overlapping suture in total knee arthroplasty for severe osteoarthritis with permanent patellar dislocation: early and mid-term results / 南方医科大学学报

OBJECTIVE@#To evaluate the early and mid-term clinical results of medial parapatellar soft tissue overlapping suture in total knee arthroplasty for treatment of severe osteoarthritis combined with permanent patellar dislocation.@*METHODS@#We retrospectively analyzed the data of 12 patients (12 knees) diagnosed with severe knee osteoarthritis combined with permanent patellar dislocation undergoing total knee arthroplasty with medial parapatellar soft tissue overlapping suture. Knee Society Score (KSS), University of California Los Angeles (UCLA) activity-level rating, Visual Analog Scale (VAS) pain score, and knee range of motion of the patients were assessed before and 2 years after the surgery. Anteroposterior and lateral radiographs of the knee joint, full-length standing radiographs of the lower limbs and patellar axial radiographs were evaluated.@*RESULTS@#The mean Knee Society Score of the patients increased from 34.2±11.1 before surgery to 73.5±6.3 at two years after the surgery (P < 0.001). The UCLA activity-level rating increased from an average of 3.8 ± 0.8 before surgery to 5.8 ± 0.6 at two years postoperatively (P=0.003). The mean VAS pain score decreased from 42.8±6.0 before surgery to 20.1±3.7 (P < 0.001) and the range of motion of the knee joint increased from 74.6±8.9 degrees to 97.5±4.5 degrees at two years (P < 0.001). The radiographs showed no signs of subluxation or dislocation of the patella in all the patients.@*CONCLUSIONS@#Medial parapatellar soft tissue overlapping suture in total knee arthroplasty can achieve good early and mid-term clinical results for treatment of severe osteoarthritis combined with permanent patellar dislocation.

Structure-based design, synthesis, and biological evaluation of novel pyrimidinone derivatives as PDE9 inhibitors

The pathological processes of Alzheimer's disease and type 2 diabetes mellitus have been demonstrated to be linked together. Both PDE9 inhibitors and PPAR agonists such as rosiglitazone exhibited remarkable preclinical and clinical treatment effects for these two diseases. In this study, a series of PDE9 inhibitors combining the pharmacophore of rosiglitazone were discovered. All the compounds possessed remarkable affinities towards PDE9 and four of them have the IC values <5 nmol/L. In addition, these four compounds showed low cell toxicity in human SH-SY5Y neuroblastoma cells. Compound , the most effective one, gave the IC of 1.1 nmol/L towards PDE9, which is significantly better than the reference compounds PF-04447943 and BAY 73-6691. The analysis of putative binding patterns and binding free energy of the designed compounds with PDE9 may explain the structure-activity relationships and provide evidence for further structural modifications.

Total knee arthroplasty with 3D printing technique versus conventional surgery: comparison of the outcomes / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare the clinical outcomes of patients receiving total knee arthroplasty (TKA) using 3D printing technique and conventional surgical methods.</p><p><b>METHODS</b>From October, 2015 to February, 2017, 17 patients (20 knees) underwent TKA with the assistance of individualized navigation template and 16 concurrent patients (18 knees) matched for age, gender and knee society score received conventional TKA. The operation time, blood loss, and osteotomy data of the femoral condyle and tibia plateau were recorded. The mean femorotibial angle (MFTA) and sagittal tibial component angle (STCA) after the operation and the KSS at the last follow-up were compared between the two groups.</p><p><b>RESULTS</b>All the patients were followed up for 7-23 months, during which no infection or prosthesis loosening or motion was found. In patients receiving surgery with 3D printing technique, the osteotomy data of the femoral condyle and tibia plateau in the actual surgeries were consistent with those in surgical plans (P>0.05). The patients in the 3D group had a significantly shorter operation time and a higher KSS score than those in the conventional group (P<0.05). Significant differences were found between the two groups in postoperative MFTA and STCA (P<0.05).</p><p><b>CONCLUSION</b>The application of 3D printing technique can simplify the surgical procedure and improve the surgical precision and efficacy of TKA.</p>