Substituted oxindol-3-ylidenes as AMP-activated protein kinase (AMPK) inhibitors

A novel pyridine-2-one AMPK inhibitor: Discovery, mechanism, and in vivo evaluation in a hypoxic pulmonary arterial hypertension rat model

AMP-activated protein kinase (AMPK), a heterotrimeric serine-threonine kinase, has been identified as a promising target for regulating vascular remodeling in pulmonary arterial hypertension (PAH) due to its capacity to promote proliferation, autophagy, and anti-apoptosis in pulmonary artery smooth muscle cells (PASMCs). However, research into AMPK inhibitors is very limited. Herein, a virtual screening strategy was employed to identify CHEMBL3780091 as a lead compound for a series of novel AMPK inhibitors by exploring the structure-activity relationship around a specific pyridine-2-one scaffold. Subsequently, the most promising 13a was observed to exhibit excellent AMPK inhibitory activity and favorable anti-proliferative activity against PASMCs through the inhibition of the AMPK signaling pathway in vitro. Moreover, compound 13a significantly reduced right ventricular systolic pressure, attenuated vascular remodeling, and improved right heart function in hypoxia-induced PAH rats in vivo. In conclusion, this study provides a novel and potential lead compound for the study of AMPK inhibitors and a new direction for the development of PAH drugs that focus on improving vascular remodeling.

Small Molecule Modulators of AMP-Activated Protein Kinase (AMPK) Activity and Their Potential in Cancer Therapy

AMP-activated protein kinase (AMPK) is a central mediator of cellular metabolism and is activated in direct response to low ATP levels. Activated AMPK inhibits anabolic pathways and promotes catabolic activities that generate ATP through the phosphorylation of multiple target substrates. AMPK is a therapeutic target for activation in several chronic metabolic diseases, and there is increasing interest in targeting AMPK activity in cancer where it can act as a tumor suppressor or conversely it can support cancer cell survival. Small molecule AMPK activators and inhibitors have demonstrated some success in suppressing cancer growth, survival, and drug resistance in preclinical cancer models. In this perspective, we summarize the role of AMPK in cancer and drug resistance, the influence of the tumor microenvironment on AMPK activity, and AMPK activator and inhibitor development. In addition, we discuss the potential importance of isoform-selective targeting of AMPK and approaches for selective AMPK targeting in cancer.

Synthesis and Evaluation of Thiazolyl-indole-2-carboxamide Derivatives as Potent Multitarget Anticancer Agents

Cancer is a complex disease driven by the dysregulation of multiple signaling pathways and cellular processes. The development of compounds capable of exerting multitarget actions against these key pathways involved in cancer progression is a promising therapeutic approach. Here, a series of novel (E/Z)-N-(4-(2-(2-(substituted)hydrazineyl)-2-oxoethyl)thiazol-2-yl)-1H-indole-2-carboxamide derivatives (6a-6z) were designed, synthesized, and evaluated for their biological activity. Compounds 6e, 6i, 6q, 6v, 7a, and 7b exhibited exceptional cytotoxicity against various cancer cell lines, particularly 6i (IC50 = 6.10 ± 0.4 μM against MCF-7 cell lines) and 6v (IC50 = 6.49 ± 0.3 μM against MCF-7 cell lines). These potent compounds inhibited key protein kinases like EGFR, HER2, VEGFR-2, and CDK2, induced cell cycle arrest at the G2/M phase, and promoted apoptosis. Docking studies revealed improved binding affinity of 6i and 6v with target proteins compared to reference drugs. These findings highlight the promising potential of 6i and 6v as multitarget cancer therapeutics deserving further development.

Knockdown of EIF2AK2-OAS1 axis reduces ATP production inducing AMPK phosphorylation to inhibit the malignant behavior of gastric cancer cells

Energy metabolism has always been a hot topic in cancer progression and targeted therapy, and exploring the role of genes in energy metabolic pathways in cancer cells has become key to address this issue. Eukaryotic translation initiation factor 2α kinase 2 (EIF2AK2) plays regulatory roles in cancer and disorders of energy metabolism. Indeed, the role of EIF2AK2 in energy metabolism has been underestimated. The aim of this study is to reveal the expression specificity of EIF2AK2 in gastric cancer (GC) progression and metastasis, and to demonstrate the role of EIF2AK2 in energy metabolism, cytoskeleton, proliferation, death and metastasis pathways in GC cells. Mechanistically, EIF2AK2 overexpression promoted cytoskeleton remodeling and ATP production, mediated cell proliferation and metastasis, upregulated OAS1 expression, decreases p-AMPK expression and inhibited apoptosis in GC cells. Conversely, knockdown of EIF2AK2 resulted in the opposite effect. However, overexpression of OAS1 mediated the upregulation of mitochondrial membrane potential and promoted ATP production and NAD+/NADH ratio, but knockdown of OAS1 inhibited the above effects. In addition, knockdown of OAS1 had no effect on EIF2AK2 expression, but inhibited AMPK and upregulated p-AMPK expression. In conclusion, our study identified EIF2AK2 and OAS1 as previously undescribed regulators of energy metabolism in GC cells. We hypothesized that EIF2AK2-OAS1 axis may regulate energy metabolism and inhibit cellular malignant behavior in cancer cells by affecting ATP production to induce AMPK phosphorylation, suggesting EIF2AK2 as a potential therapeutic target for cancer cell progression.

A Novel AMPK Inhibitor Sensitizes Pancreatic Cancer Cells to Ferroptosis Induction

Cancer cells must develop strategies to adapt to the dynamically changing stresses caused by intrinsic or extrinsic processes, or therapeutic agents. Metabolic adaptability is crucial to mitigate such challenges. Considering metabolism as a central node of adaptability, it is focused on an energy sensor, the AMP-activated protein kinase (AMPK). In a subtype of pancreatic ductal adenocarcinoma (PDAC) elevated AMPK expression and phosphorylation is identified. Using drug repurposing that combined screening experiments and chemoproteomic affinity profiling, it is identified and characterized PF-3758309, initially developed as an inhibitor of PAK4, as an AMPK inhibitor. PF-3758309 shows activity in pre-clinical PDAC models, including primary patient-derived organoids. Genetic loss-of-function experiments showed that AMPK limits the induction of ferroptosis, and consequently, PF-3758309 treatment restores the sensitivity toward ferroptosis inducers. The work established a chemical scaffold for the development of specific AMPK-targeting compounds and deciphered the framework for the development of AMPK inhibitor-based combination therapies tailored for PDAC.

Novel sulfonamide-indolinone hybrids targeting mitochondrial respiration of breast cancer cells

Breast cancer (BC) still poses a threat worldwide which demands continuous efforts to present safer and efficacious treatment options via targeted therapy. Beside kinases' aberrations as Aurora B kinase which controls cell division, BC adopts distinct metabolic profiles to meet its high energy demands. Accordingly, targeting both aurora B kinase and/or metabolic vulnerability presents a promising approach to tackle BC. Based on a previously reported indolinone-based Aurora B kinase inhibitor (III), and guided by structural modification and SAR investigation, we initially synthesized 11 sulfonamide-indolinone hybrids (5a-k), which showed differential antiproliferative activities against the NCI-60 cell line panel with BC cells displaying preferential sensitivity. Nonetheless, modest activity against Aurora B kinase (18-49% inhibition) was noted at 100 nM. Screening of a representative derivative (5d) against 17 kinases, which are overexpressed in BC, failed to show significant activity at 1 μM concentration, suggesting that kinase inhibitory activity only played a partial role in targeting BC. Bioinformatic analyses of genome-wide transcriptomics (RNA-sequencing), metabolomics, and CRISPR loss-of-function screens datasets suggested that indolinone-completely responsive BC cell lines (MCF7, MDA-MB-468, and T-47D) were more dependent on mitochondrial oxidative phosphorylation (OXPHOS) compared to partially responsive BC cell lines (MDA-MB-231, BT-549, and HS 578 T). An optimized derivative, TC11, obtained by molecular hybridization of 5d with sunitinib polar tail, manifested superior antiproliferative activity and was used for further investigations. Indeed, TC11 significantly reduced/impaired the mitochondrial respiration, as well as mitochondria-dependent ROS production of MCF7 cells. Furthermore, TC11 induced G0/G1 cell cycle arrest and apoptosis of MCF7 BC cells. Notably, anticancer doses of TC11 did not elicit cytotoxic effects on normal cardiomyoblasts and hepatocytes. Altogether, these findings emphasize the therapeutic potential of targeting the metabolic vulnerability of OXPHOS-dependent BC cells using TC11 and its related sulfonamide-indolinone hybrids. Further investigation is warranted to identify their precise/exact molecular target.

Is It Possible to Obtain a Product of the Desired Configuration from a Single Knoevenagel Condensation? Isomerization vs. Stereodefined Synthesis

The biological activity of compounds directly depends on the three-dimensional arrangement of affinity fragments since a high degree of pharmacophore compliance with the binding site is required. 3-Benzylidene oxindoles are privileged structures due to their wide spectrum of biological activity, synthetic availability, and ease of modification. In particular, both kinase inhibitors and kinase activators can be found among 3-benzylidene oxindoles. In this work, we studied model compounds obtained via oxindole condensation with aldehydes and alkylphenones. These condensation products can exist in the form of E- and Z-isomers and also undergo isomerization in solutions. The factors causing isomeric transformation of these compounds were established. Comparative kinetic studies to obtain quantitative characteristics of UV-driven isomerization were first performed. The results obtained indicate dramatic differences in two subclasses, which should be considered when developing biologically active molecules.

Difluorocarbene-Enabled Synthesis of 3-Alkenyl-2-oxindoles from ortho-Aminophenylacetylenes

Herein, we report a transition-metal-free [4 + 1] cyclization pathway from difluorocarbene and ortho-amino aryl alkynone, rendering an effective and universal strategy for the construction of 3-alkenyl-2-oxindoles. Our strategy starts from cheap and accessible ortho-amino aryl alkynone instead of the direct indole skeleton; moreover, in situ generated difluorocarbene from commercially available halogenated difluoroalkylative reagents enables the cleavage of a C-N bond and formation of new C-N bonds and C-C bonds.

A switchable redox annulation of 2-nitroarylethanols affording N-heterocycles: photoexcited nitro as a multifunctional handle

The efficient transformation of nitroaromatics to functional molecules such as N-heterocycles has been an attractive and significant topic in synthesis chemistry. Herein, a photoexcited nitro-induced strategy for switchable annulations of 2-nitroarylethanols was developed to construct N-heterocycles including indoles, N-hydroxyl oxindoles and N-H oxindoles. The metal- and photocatalyst-free reaction proceeds through intramolecular redox C-N coupling of branched hydroxyalkyl and nitro units, which is initiated by a double hydrogen atom abstraction (d-HAA) process. The key to the switchable reaction outcomes is the mediation of a diboron reagent by its favorable oxy-transfer reactivity to in situ generated nitroso species. The utility of this protocol was well demonstrated by broad substrate scope, excellent yields, functional group tolerance and wide applications. Finally, detailed mechanistic studies were performed, and kinetic isotope effect (KIE) experiments indicate that the homolysis of the C-H bond is involved in the rate-determining step.

An approach to pharmacological targets of pyrrole family from a medicinal chemistry viewpoint

Pyrrole is one of the most widely used heterocycles in the pharmaceutical industry. Due to the importance of pyrrole structure in drug design and development, herein, we tried to conduct an extensive review of the bioactive pyrrole based compounds reported recently. The bioactivity of pyrrole derivatives varies, so in the review, we categorized them based on their direct pharmacologic targets. Therefore, readers are able to find the variety of biologic targets for pyrrole containing compounds easily. This review explains around seventy different biologic targets for pyrrole based derivatives, so, it is helpful for medicinal chemists in design and development novel bioactive compounds for different diseases. This review presents an extensive meaningful structure activity relationship for each reported structure as much as possible. The review focuses on papers published between 2018 and 2020.

Indolin-2-one derivatives as selective Aurora B kinase inhibitors targeting breast cancer

Aurora B is a pivotal cell cycle regulator where errors in its function results in polyploidy, genetic instability, and tumorigenesis. It is overexpressed in many cancers, consequently, targeting Aurora B with small molecule inhibitors constitutes a promising approach for anticancer therapy. Guided by structure-based design and molecular hybridization approach we developed a series of fifteen indolin-2-one derivatives based on a previously reported indolin-2-one-based multikinase inhibitor (1). Seven derivatives, 5g, 6a, 6c-e, 7, and 8a showed preferential antiproliferative activity in NCI-60 cell line screening and out of these, carbamate 6e and cyclopropylurea 8a derivatives showed optimum activity against Aurora B (IC₅₀ = 16.2 and 10.5 nM respectively) and MDA-MB-468 cells (IC₅₀ = 32.6 ± 9.9 and 29.1 ± 7.3 nM respectively). Furthermore, 6e and 8a impaired the clonogenic potential of MDA-MB-468 cells. Mechanistic investigations indicated that 6e and 8a induced G2/M cell cycle arrest, apoptosis, and necrosis of MDA-MB-468 cells and western blot analysis of 8a effect on MDA-MB-468 cells revealed 8a's ability to reduce Aurora B and its downstream target, Histone H3 phosphorylation. 6e and 8a displayed better safety profiles than multikinase inhibitors such as sunitinib, showing no cytotoxic effects on normal rat cardiomyoblasts and murine hepatocytes. Finally, 8a demonstrated a more selective profile than 1 when screened against ten related kinases. Based on these findings, 8a represents a promising candidate for further development to target breast cancer via Aurora B selective inhibition.

Structural insights of oxindole based kinase inhibitors as anticancer agents: Recent advances

Small-molecule kinase inhibitors are being continuously explored as new anticancer therapeutics. Kinases are the phosphorylating enzymes which regulate numerous cellular functions such as proliferation, differentiation, migration, metabolism, and angiogenesis by activating several signalling pathways. Kinases have also been frequently found to be deregulated and overexpressed in cancerous tissues. Therefore, modulating the kinase activity by employing small molecules has emerged as a strategic approach for cancer treatment. On the other hand, oxindole motifs have surfaced as privileged scaffolds with significant multi-kinase inhibitory activity. The present review summarises recent advances in the development of oxindole based kinase inhibitors. The role of distinguished structural frameworks of oxindoles, such as 3-alkenyl oxindoles, spirooxindoles, 3-iminooxindoles and similar hydrazone derivatives have been described based on their kinase inhibition potential. Furthermore, the design strategies, mechanism of actions, structure activity relationships (SARs) and their mode of interaction with target protein have been critically highlighted.

The potent AMPK inhibitor BAY-3827 shows strong efficacy in androgen-dependent prostate cancer models

PURPOSE

5' adenosine monophosphate-activated kinase (AMPK) is an essential regulator of cellular energy homeostasis and has been associated with different pathologies, including cancer. Precisely defining the biological role of AMPK necessitates the availability of a potent and selective inhibitor.

METHODS

High-throughput screening and chemical optimization were performed to identify a novel AMPK inhibitor. Cell proliferation and mechanistic assays, as well as gene expression analysis and chromatin immunoprecipitation were used to investigate the cellular impact as well as the crosstalk between lipid metabolism and androgen signaling in prostate cancer models. Also, fatty acid turnover was determined by examining lipid droplet formation.

RESULTS

We identified BAY-3827 as a novel and potent AMPK inhibitor with additional activity against ribosomal 6 kinase (RSK) family members. It displays strong anti-proliferative effects in androgen-dependent prostate cancer cell lines. Analysis of genes involved in AMPK signaling revealed that the expression of those encoding 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR), fatty acid synthase (FASN) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2), all of which are involved in lipid metabolism, was strongly upregulated by androgen in responsive models. Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) analysis identified several androgen receptor (AR) binding peaks in the HMGCR and PFKFB2 genes. BAY-3827 strongly down-regulated the expression of lipase E (LIPE), cAMP-dependent protein kinase type II-beta regulatory subunit (PRKAR2B) and serine-threonine kinase AKT3 in responsive prostate cancer cell lines. Also, the expression of members of the carnitine palmitoyl-transferase 1 (CPT1) family was inhibited by BAY-3827, and this was paralleled by impaired lipid flux.

CONCLUSIONS

The availability of the potent inhibitor BAY-3827 will contribute to a better understanding of the role of AMPK signaling in cancer, especially in prostate cancer.

Synthesis of C3-alkenylated 2,3,4-trisubstituted pyrrole derivatives through cyclization of methylene isocyanides and ene–yne–ketones

A mild, transition-metal-free and facile C3-alkenylated 2,3,4-trisubstituted pyrrole cyclization of methylene isocyanides with ene–yne–ketones in moderate to good yields was explored.