I2/CF3CO2Ag-mediated iodolactonization of various allenoic acids to access versatile 6- to 9-membered ring vinylic iodolactones.

Medium-sized lactones are important structural units, but their synthesis remains a great challenge. Herein, we report I2/CF3CO2Ag-mediated iodolactonization of allenoic acids to synthesize various 6- to 9-membered ring vinylic iodolactones in 16-89% yield. This protocol not only develops a new cyclization strategy of allenoic acids, but also provides highly functionalized medium-sized lactones containing alkene and halogen groups.

Inhibiting G6PD by quercetin promotes degradation of EGFR T790M mutation.

EGFRT790M mutation causes resistance to the first-generation tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). However, the therapeutic options for sensitizing first TKIs and delaying the emergence of EGFRT790M mutant are limited. In this study, we show that quercetin directly binds with glucose-6-phosphate dehydrogenase (G6PD) and inhibits its enzymatic activity through competitively abrogating NADP+ binding in the catalytic domain. This inhibition subsequently reduces intracellular NADPH levels, resulting in insufficient substrate for methionine reductase A (MsrA) to reduce M790 oxidization of EGFRT790M and inducing the degradation of EGFRT790M. Quercetin synergistically enhances the therapeutic effect of gefitinib on EGFRT790M-harboring NSCLCs and delays the acquisition of the EGFRT790M mutation. Notably, high levels of G6PD expression are correlated with poor prognosis and the emerging time of EGFRT790M mutation in patients with NSCLC. These findings highlight the potential implication of quercetin in overcoming EGFRT790M-driven TKI resistance by directly targeting G6PD.

Discovery of benzyloxy benzamide derivatives as potent neuroprotective agents against ischemic stroke.

Aberrant activation of N-methyl-d-aspartate receptors (NMDAR) and the resulting neuronal nitric oxide synthase (nNOS) excessive activation play crucial pathogenic roles in neuronal damage caused by stroke. Disrupting postsynaptic density protein 95 (PSD95)-nNOS protein-protein interaction (PPI) has been proposed as a potential therapeutic strategy for ischemic stroke without incurring the unwanted side effects of direct NMDAR antagonism. Based on a specific PSD95-nNOS PPI inhibitor (SCR4026), we conducted a detailed study on structure-activity relationship (SAR) to discover a series of novel benzyloxy benzamide derivatives. Here, our efforts resulted in the best 29 (LY836) with improved neuroprotective activities in primary cortical neurons from glutamate-induced damage and drug-like properties. Whereafter, co-immunoprecipitation experiment demonstrated that 29 significantly blocked PSD95-nNOS association in cultured cortical neurons. Furthermore, 29 displayed good pharmacokinetic properties (T1/2 = 4.26 and 4.08 h after oral and intravenous administration, respectively) and exhibited powerful therapeutic effects in rats subjected to middle cerebral artery occlusion (MCAO) by reducing infarct size and neurological deficit score. These findings suggested that compound 29 may be a promising neuroprotection agent for the treatment of ischemic stroke.

Synthesis and Bioevaluation of 3-(Arylmethylene)indole Derivatives: Discovery of a Novel ALK Modulator with Antiglioblastoma Activities.

Glioblastoma is the most common brain tumor, with high recurrence and low survival rates. An integrative bioinformatics analysis demonstrated that anaplastic lymphoma kinase (ALK) is a promising therapeutic target for glioblastoma. We designed and synthesized a series of 3-(arylmethylene)indole derivatives, which were further evaluated for antiproliferative activity using glioma cell lines. Among them, compound 4a significantly inhibited the viability of glioblastoma cells. With favorable pharmacokinetic characteristics and blood-brain barrier permeability, 4a improved the survival rate and inhibited the growth of orthotopic glioblastoma. The Phospho-Totum system revealed that ALK was a potential target for the antiglioblastoma activity of 4a. Further experiments indicated that 4a might be a novel ALK modulator, which interacted with the extracellular ligand-binding domain of ALK, thus selectively induced ERK-mediated autophagy and apoptosis. Our findings provide an alternative ALK-based targeting strategy and a new drug candidate for glioblastoma therapy.

Hypoxanthine phosphoribosyl transferase 1 metabolizes temozolomide to activate AMPK for driving chemoresistance of glioblastomas.

Temozolomide (TMZ) is a standard treatment for glioblastoma (GBM) patients. However, TMZ has moderate therapeutic effects due to chemoresistance of GBM cells through less clarified mechanisms. Here, we demonstrate that TMZ-derived 5-aminoimidazole-4-carboxamide (AICA) is converted to AICA ribosyl-5-phosphate (AICAR) in GBM cells. This conversion is catalyzed by hypoxanthine phosphoribosyl transferase 1 (HPRT1), which is highly expressed in human GBMs. As the bona fide activator of AMP-activated protein kinase (AMPK), TMZ-derived AICAR activates AMPK to phosphorylate threonine 52 (T52) of RRM1, the catalytic subunit of ribonucleotide reductase (RNR), leading to RNR activation and increased production of dNTPs to fuel the repairment of TMZ-induced-DNA damage. RRM1 T52A expression, genetic interruption of HPRT1-mediated AICAR production, or administration of 6-mercaptopurine (6-MP), a clinically approved inhibitor of HPRT1, blocks TMZ-induced AMPK activation and sensitizes brain tumor cells to TMZ treatment in mice. In addition, HPRT1 expression levels are positively correlated with poor prognosis in GBM patients who received TMZ treatment. These results uncover a critical bifunctional role of TMZ in GBM treatment that leads to chemoresistance. Our findings underscore the potential of combined administration of clinically available 6-MP to overcome TMZ chemoresistance and improve GBM treatment.

JP1 normalizes tumor vasculature to suppress metastasis and facilitate drug delivery by inhibiting IL-8.

Tumor vascular normalization prevents tumor cells from breaking through the basement membrane and entering the vasculature, thereby inhibiting metastasis initiation. In this study, we report that the antitumor peptide JP1 regulated mitochondrial metabolic reprogramming through AMPK/FOXO3a/UQCRC2 signaling, which improved the tumor microenvironment hypoxia. The oxygen-rich tumor microenvironment inhibited the secretion of IL-8 by tumor cells, thereby promoting tumor vascular normalization. The normalized vasculature resulted in mature and regular blood vessels, which made the tumor microenvironment form a benign feedback loop consisting of vascular normalization, sufficient perfusion, and an oxygen-rich microenvironment, prevented tumor cells from entering the vasculature, and inhibited metastasis initiation. Moreover, the combined therapy of JP1 and paclitaxel maintained a certain vascular density in the tumor and promoted tumor vascular normalization, increasing the delivery of oxygen and drugs and enhancing the antitumor effect. Collectively, our work highlights the antitumor peptide JP1 as an inhibitor of metastasis initiation and its mechanism of action.

Synthesis of 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes via Er(OTf)3-catalyzed cascade reactions of p-quinone methides with 1,3-dicarbonyl compounds.

The Er(OTf)3-catalyzed cascade cyclization reaction of para-quinone methides (p-QMs) with various 1,3-dicarbonyl compounds has been developed, which efficiently constructed a series of versatile 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes. Herein, we not only propose a novel cyclization strategy of p-QMs, but also provide an easy access to structurally diverse coumarins and chromenes.

Discovery of cysteine-targeting covalent histone methyltransferase inhibitors.

Post-translational methylation of histone lysine or arginine residues by histone methyltransferases (HMTs) plays crucial roles in gene regulation and diverse physiological processes and is implicated in a plethora of human diseases, especially cancer. Therefore, histone methyltransferases have been increasingly recognized as potential therapeutic targets. Consequently, the discovery and development of histone methyltransferase inhibitors have been pursued with steadily increasing interest over the past decade. However, the disadvantages of limited clinical efficacy, moderate selectivity, and propensity for acquired resistance have hindered the development of HMTs inhibitors. Targeted covalent modification represents a proven strategy for kinase drug development and has gained increasing attention in HMTs drug discovery. In this review, we focus on the discovery, characterization, and biological applications of covalent inhibitors for HMTs with emphasis on advancements in the field. In addition, we identify the challenges and future directions in this fast-growing research area of drug discovery.

Argininosuccinate lyase drives activation of mutant TERT promoter in glioblastomas.

Cancer-specific TERT promoter mutations have been linked to the reactivation of epigenetically silenced TERT gene by creating de novo binding motifs for E-Twenty-Six transcription factors, especially GABPA. How these mutations switch on TERT from epigenetically repressed states to expressed states have not been defined. Here, we revealed that EGFR activation induces ERK1/2-dependent phosphorylation of argininosuccinate lyase (ASL) at Ser417 (S417), leading to interactions between ASL and GABPA at the mutant regions of TERT promoters. The ASL-generated fumarate inhibits KDM5C, leading to enhanced trimethylation of histone H3 Lys4 (H3K4me3), which in turn promotes the recruitment of c-Myc to TERT promoters for TERT expression. Expression of ASL S417A, which abrogates its binding with GABPA, results in reduced TERT expression, inhibited telomerase activity, shortened telomere length, and impaired brain tumor growth in mice. This study reveals an unrecognized mechanistic insight into epigenetically activation of mutant TERT promoters where GABPA-interacted ASL plays an instrumental role.

Discovery of 1-(Hetero)aryl-ß-carboline Derivatives as IDO1/TDO Dual Inhibitors with Antidepressant Activity.

Depression is the leading cause of global burden of disease and disability. Abnormalities in the kynurenine pathway of tryptophan degradation have been closely linked to the pathogenesis of depression. An integrative bioinformatics analysis demonstrated that indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO) are potential targets for the development of antidepressants. A series of 1-(hetero)aryl-ß-carboline derivatives were designed, synthesized, and evaluated as novel IDO1/TDO dual inhibitors. Among them, compound 28 displayed potent inhibition of both IDO1 (IC50 = 3.53 µM) and TDO (IC50 = 1.15 µM) and had an acceptable safety profile and pharmacokinetic properties. Compound 28 also rescued lipopolysaccharide-induced depressive-like behavior in mice. Further studies revealed that 28 likely had unique antidepressant mechanisms involving suppressing microglial activation, lowering IDO1 expression, and reducing proinflammatory cytokine and kynurenine levels in the mouse brain. Overall, this work provides practical guidance for the development of IDO1/TDO dual inhibitors to treat inflammation-induced depression.

JAC1 targets YY1 mediated JWA/p38 MAPK signaling to inhibit proliferation and induce apoptosis in TNBC.

Triple negative breast cancer (TNBC) is a type of breast cancer with poor prognosis, and has no ideal therapeutic target and ideal medicine. Downregulation of JWA is closely related to the poor overall survival in many cancers including TNBC. In this study, we reported at the first time that JWA gene activating compound 1 (JAC1) inhibited the proliferation of TNBC in vitro and in vivo experimental models. JAC1 specifically bound to YY1 and eliminated its transcriptional inhibition of JWA gene. The rescued JWA induced G1 phase arrest and apoptosis in TNBC cells through the p38 MAPK signaling pathway. JAC1 also promoted ubiquitination and degradation of YY1. In addition, JAC1 disrupted the interaction between YY1 and HSF1, and suppressed the oncogenic role of HSF1 in TNBC through p-Akt signaling pathway. In conclusion, JAC1 suppressed the proliferation of TNBC through the JWA/P38 MAPK signaling and YY1/HSF1/p-Akt signaling. JAC1 maybe a potential therapeutic agent for TNBC.

Mutagenicity risk prediction of PAH and derivative mixtures by in silico simulations oriented from CYP compound I-mediated metabolic activation.

PAHs and their derivatives are the main sources of mutagenicity and carcinogenicity in airborne particular matter and cause serious public health and environmental problems. Risk assessment is challenging due to the mixed nature and deficiency of toxicity data of most PAHs and their derivatives. Cytochrome P450 enzymes (CYPs) play important roles in PAH-induced carcinogenicity via metabolic activation, and CYP conformations with compound I structures strongly influence metabolic sites and metabolite species. In this study, complexes of BaP with CYP1A1, CYP1B1 or CYP2C19 compound I were successfully simulated by QM/MM methods and verified by metabolic clearance, and the mutagenicity of chemicals was then predicted by the BaP-7,8-epoxide-related metabolic conformation fitness (MCF) approach, which was validated by Ames tests, showing satisfying accuracy (R2 = 0.46-0.66). Furthermore, a prediction model of the mutagenicity risk of PAH and derivative mixtures was established based on the relative potential factor (RPF) approach and the RPF calculated from the mathematical relationship between the minimum MCF (MCFmin) and RPF, which was successfully validated by the mutagenesis of PAH and derivative mixture mimic-simulating PM2.5 samples collected in eastern China. This study provides fast reliable tools for assessing risk of the complex components of environmental PAHs and their derivatives.

JAC1 suppresses proliferation of breast cancer through the JWA/p38/SMURF1/HER2 signaling.

The overexpression of HER2 is associated with a malignant proliferation of breast cancer. In this study, we developed a non-cytotoxic JWA gene activating compound 1 (JAC1) to inhibit the proliferation of HER2-positive breast cancer cells in vitro and in vivo experimental models. JAC1 increased the ubiquitination of HER2 at the K716 site through the E3 ubiquitin ligase SMURF1 which was due to the decreased expression of NEDD4, the E3 ubiquitin ligase of SMURF1. In conclusion, JAC1 suppresses the proliferation of HER2-positive breast cancer cells through the JWA triggered HER2 ubiquitination signaling. JAC1 may serve as a potential therapeutic agent for HER2-positive breast cancer.

JP3 enhances the toxicity of cisplatin on drug-resistant gastric cancer cells while reducing the damage to normal cells.

Background: Cisplatin (DDP) is a highly effective chemotherapeutic agent to most solid tumors including gastric cancer (GC), however, its clinical value is limited due to severe toxic side effects and secondary drug resistance. JP3, a JWA protein based MMP2-targeted polypeptide, known to inhibit the growth of GC in vivo. However, the bidirectional effects of JP3 in DDP-resistant GC and normal cells have not been demonstrated. The present study aims to investigate the actions of JP3 on protecting normal cells from the toxicity of DDP while enhancing its anti-tumor effects on GC cells. Methods: Routine laboratory experimental methods including CCK-8 assay, Western blotting, Hoechst staining, immunofluorescence (IF) and qRT-PCR were used in mechanism investigation; protein docking analysis and coimmunoprecipitation (Co-IP) were used for prediction and confirmation of interactions between JP3 and CK2. Mouse xenograft model was used for screening the treatment of JP3 plus DDP on GC growth. Results: DDP showed similar toxicities to normal cells and DDP-resistant GC cells; JP3 competitively inhibited the binding of XRCC1 to CK2, reduced the DNA repair and anti-apoptosis capacity of DDP-resistant GC cells in combination with DDP treatment; meanwhile, JP3 protected normal cells from DDP-induced oxidative stress and DNA damage through ERK/Nrf2 signaling. JP3 combined with DDP showed similar bidirectional effects in vivo. Conclusions: JP3 enhanced the inhibitory effects of DDP on tumor growth while reduced toxic side effects of DDP on normal cells. The results of this study provide a new insight for the treatment of drug-resistant GC.

JP1 suppresses proliferation and metastasis of melanoma through MEK1/2 mediated NEDD4L-SP1-Integrin αvß3 signaling.

Background: JWA gene is known to down-regulate SP1 and reduces the expression level of Integrin αvß3. Here, we identified a functional polypeptide (JP1) based on the active fragment of the JWA protein to suppress melanoma growth and metastasis by inhibiting the Integrin αvß3. Methods: We conducted a series of melanoma growth and metastasis mouse models to evaluate anti-melanoma effect of JP1 peptide. 18F-labeled JP1 (18F-NFP-JP1) was detected by Micro-PET assay to demonstrate drug biodistribution. Toxicity test in cynomolgus monkeys and pharmacokinetic studies in rats were done to assess the druggability. The expression of MEK1/2, NEDD4L, SP1 and Integrin αvß3 were detected in vitro and vivo models. Results: The peptide JP1 with the best anticancer effect was obtained. Micro-PET assay showed that JP1 specifically targeting to melanoma cells in vivo. JP1 inhibited melanoma growth, metastasis, and prolonged the survival of mouse. JP1 reduced the dosage and toxicity in combination with DTIC in melanoma xenograft and allograft mouse models. Cynomolgus monkey toxicity test showed no observed adverse effect level (NOAEL) of JP1 was 150 mg/kg. Mechanistically, JP1 was shown to activate p-MEK1/2 and triggered SP1 ubiquitination in melanoma cells. NEDD4L, an E3 ubiquitin ligase, was activated by p-MEK1/2 and to ubiquitinate SP1 at K685 site, resulting in subsequent degradation. Conclusions: JP1 was developed as a novel peptide that indicated therapeutic roles on proliferation and metastasis of melanoma through the NEDD4L-SP1-Integrin αvß3 signaling.

JP3, an antiangiogenic peptide, inhibits growth and metastasis of gastric cancer through TRIM25/SP1/MMP2 axis.

BACKGROUND: Gastric cancer (GC) is the most prevalent gastrointestinal tumor with an unfavorable clinical prognosis. GC patients are largely threatened owing to metastasis and drug resistance. Tumor angiogenesis plays an important role in the development of gastric cancer and is a challenge in the treatment of gastric cancer. METHODS: Mouse xenograft models were used for screening of therapeutic peptides on GC growth and metastasis. Routine laboratory experimental methods including conditional cell culture, tube formation assay, qRT-PCR, Western blotting, immunohistochemistry (IHC), ubiquitination assay, and immunofluorescence (IF) were used in mechanism investigation; protein docking analysis and coimmunoprecipitation (Co-IP) were used for prediction and confirmation of interactions between JP3/SP1 and TRIM25/MEK1/2. RESULTS: We identified an MMP2-targeted peptide JP3 that plays inhibiting roles in modulating growth and metastasis of GC in vivo and has no observable toxic side effects. JP3 reduced tumor microvessel density (MVD) in vivo and human umbilical vein endothelial cells (HUVECs) tube formation in vitro. Mechanistic studies revealed that JP3 reduces polyubiquitination-mediated degradation of TRIM25 by increasing the stability of TRIM25 through phosphorylating it at Ser12. TRIM25, as an E3 ubiquitin ligase, promoted the ubiquitin of SP1 at K610, further suppressed expression of MMP2 and inhibited angiogenesis in GC. Importantly, the inversely association between TRIM25 and SP1 protein level was further verified in human GC tissues. Decreased TRIM25 expression and increased SP1 expression in tumor tissues were positively correlated with poor prognosis of GC patients. CONCLUSIONS: MMP2-targeted peptide JP3 plays a therapeutic role in GC through anti-angiogenesis by modulating TRIM25/SP1/MMP2.

Synthesis, biological evaluation and SAR studies of ursolic acid 3ß-ester derivatives as novel CETP inhibitors.

Cholesteryl ester transfer protein (CETP) is an attractive therapeutic target for the prevention and treatment of cardiovascular diseases by lowering low-density lipoprotein cholesterol levels as well as raising high-density lipoprotein cholesterol levels in human plasma. Herein, a series of ursolic acid 3ß-ester derivatives were designed, synthesized and evaluated for the CETP inhibiting activities. Among these compounds, the most active compound is U12 with an IC50 value of 2.4 µM in enzymatic assay. The docking studies showed that the possible hydrogen bond interactions between the carboxyl groups at both ends of the molecule skeleton and several polar residues (such as Ser191, Cys13 and Ser230) in the active site region of CETP could significantly enhance the inhibition activity. This study provides structural insight of the interactions between these pentacyclic triterpenoid 3ß-ester derivatives and CETP protein for the further modification and optimization.

Practical Synthesis of α-Amyrin, ß-Amyrin, and Lupeol: The Potential Natural Inhibitors of Human Oxidosqualene Cyclase.

A practical synthesis of α-amyrin (1), ß-amyrin (2), and lupeol (3) was accomplished in total yields of 32, 42, and 40% starting from easily available ursolic acid (4), oleanolic acid (5), and betulin (6), respectively. Remarkably, these three natural pentacyclic triterpenes exhibited potential inhibitory activity against human oxidosqualene cyclase.

Discovery of pentacyclic triterpene 3ß-ester derivatives as a new class of cholesterol ester transfer protein inhibitors.

A series of pentacyclic triterpene 3ß-ester derivatives were designed, synthesized and evaluated as a new class of cholesteryl ester transfer protein (CETP) inhibitors for the treatment of dyslipidemia. In vitro screening assay showed that 5 out of 30 compounds displayed moderate inhibiting human CETP activity with IC50s less than 10 µM. Among them, compound 20 (IC50 = 2.3 µM) had the most potent biological activity, and effectively ameliorated plasma lipid levels of human adipose tissue specific CETP transgenic (ap2-CETPTg) mice and guinea pigs. Additional safety evaluation (no blood pressure elevation in guinea pigs) and pharmacokinetics studies indicated that the potential druggability for compound 20 which is a promising lead for development of a new class of CETP inhibitors for the treatment of dyslipidemia.