Signal transducer and activator of transcription 3 (STAT3) is an attractive cancer therapeutic target. Here we report the discovery of SD-36, a small-molecule degrader of STAT3. SD-36 potently induces the degradation of STAT3 protein in vitro and in vivo and demonstrates high selectivity over other STAT members. Induced degradation of STAT3 results in a strong suppression of its transcription network in leukemia and lymphoma cells. SD-36 inhibits the growth of a subset of acute myeloid leukemia and anaplastic large-cell lymphoma cell lines by inducing cell-cycle arrest and/or apoptosis. SD-36 achieves complete and long-lasting tumor regression in multiple xenograft mouse models at well-tolerated dose schedules. Degradation of STAT3 protein, therefore, is a promising cancer therapeutic strategy.
The estrogen receptor (ER) is a validated target for the treatment of estrogen receptor-positive (ER+) breast cancer. Here, we describe the design, synthesis, and extensive structure–activity relationship (SAR) studies of small-molecule ERα degraders based on the proteolysis targeting chimeras (PROTAC) concept. Our efforts have resulted in the discovery of highly potent and effective PROTAC ER degraders, as exemplified by ERD-308 (32). ERD-308 achieves DC50 (concentration causing 50% of protein degradation) values of 0.17 and 0.43 nM in MCF-7 and T47D ER+ breast cancer cell lines, respectively, and induces >95% of ER degradation at concentrations as low as 5 nM in both cell lines. Significantly, ERD-308 induces more complete ER degradation than fulvestrant, the only approved selective ER degrader (SERD), and is more effective in inhibition of cell proliferation than fulvestrant in MCF-7 cells. Further optimization of ERD-308 may lead to a new therapy for advanced ER+ breast cancer.
The relationship of triglycerides (TG) to the risk of death remains uncertain. The aim of this study was to determine the associations between blood triglyceride levels and cardiovascular diseases (CVDs) mortality and all-cause mortality. Four databases were searched without language restriction for relevant studies: PubMed, ScienceDirect, EMBASE, and Google Scholar. All prospective cohort studies reporting an association between TG and CVDs or all-cause mortality published before July 2013 were included. Risk ratios (RRs) with 95% confidence intervals (CIs) were extracted and pooled according to TG categories, unit TG, and logarithm of TG using a random-effects model with inverse-variance weighting. We identified 61 eligible studies, containing 17,018 CVDs deaths in 726,030 participants and 58,419 all-cause deaths in 330,566 participants. Twelve and fourteen studies, respectively, reported the effects estimates of CVDs and total mortality by TG categories. Compared to the referent (90–149 mg/dL), the pooled RRs (95% CI) of CVDs mortality for the lowest (< 90 mg/dL), borderline-high (150–199 mg/dL), and high TG (≥ 200 mg/dL) groups were 0.83 (0.75 to 0.93), 1.15 (1.03 to 1.29), and 1.25 (1.05 to 1.50); for total mortality they were 0.94 (0.85 to 1.03), 1.09 (1.02 to 1.17), and 1.20 (1.04 to 1.38), respectively. The risks of CVDs and all-cause deaths were increased by 13% and 12% (p < 0.001) per 1-mmol/L TG increment in twenty-two and twenty-two studies reported RRs per unit TG, respectively. In conclusion, elevated blood TG levels were dose-dependently associated with higher risks of CVDs and all-cause mortality.
Signal transducer and activator of transcription 3 (STAT3) is a transcription factor and an attractive therapeutic target for cancer and other human diseases. Despite 20 years of persistent research efforts, targeting STAT3 has been very challenging. We report herein the structure-based discovery of potent small-molecule STAT3 degraders based upon the proteolysis targeting chimera (PROTAC) concept. We first designed SI-109 as a potent, small-molecule inhibitor of the STAT3 SH2 domain. Employing ligands for cereblon/cullin 4A E3 ligase and SI-109, we obtained a series of potent PROTAC STAT3 degraders, exemplified by SD-36. SD-36 induces rapid STAT3 degradation at low nanomolar concentrations in cells and fails to degrade other STAT proteins. SD-36 achieves nanomolar cell growth inhibitory activity in leukemia and lymphoma cell lines with high levels of phosphorylated STAT3. A single dose of SD-36 results in complete STAT3 protein degradation in xenograft tumor tissue and normal mouse tissues. SD-36 achieves complete and long-lasting tumor regression in the Molm-16 xenograft tumor model at well-tolerated dose-schedules. SD-36 is a potent, selective, and efficacious STAT3 degrader.
Numerous clinical trials have examined the role of anthocyanins on cardiometabolic health, but their effects have not been quantitatively synthesized and systematically evaluated. The aim of our study was to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) assessing the effects of anthocyanins on glycemic regulation and lipid profiles in both healthy populations and those with cardiometabolic diseases. The MEDLINE, EMBASE, Cochrane database, OVID EBM Reviews, and clinicaltrials.gov databases were searched until February 2017. RCTs with a duration of ≥2 wk that evaluated the effects of anthocyanins on glycemic control, insulin sensitivity, and lipids as either primary or secondary outcomes were included. The Cochrane Risk of Bias tool was used to assess the study quality. Standardized mean differences (SMDs) were determined by random-effects models. Meta-regression, sensitivity, and subgroup analyses were performed to explore the influence of covariates on the overall effects. Thirty-two RCTs (1491 participants) were eligible for meta-analysis. Anthocyanins significantly reduced fasting glucose (SMD: -0.31; 95% CI: -0.59, -0.04; = 80.7%), 2-h postprandial glucose (SMD: -0.82; 95% CI: -1.49, -0.15; = 77.7), glycated hemoglobin (SMD: -0.65; 95% CI: -1.00, -0.29; = 72.7%), total cholesterol (SMD: -0.33; 95% CI: -0.62, -0.03; = 86.9%), and LDL (SMD: -0.35; 95% CI: -0.66, -0.05; = 85.2%). Sensitivity analyses showed that the overall effects remained similar by excluding the trials with a high or unclear risk of bias. The significant improvements in glycemic control and lipids support the benefits of anthocyanins in the prevention and management of cardiometabolic disease. Further well-designed RCTs are needed to evaluate the long-term effects of anthocyanins on metabolic profiles and to explore the optimal formula and dosage. The protocol for this review was registered at https://www.crd.york.ac.uk/PROSPERO/#index.php as CRD42016033210.
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