Identification of quinones as novel PIM1 kinase inhibitors

Molecular docking and dynamics simulation study of quinones and pyrones from Alternaria solani and Alternaria alternata with HSP90: an important therapeutic target of cancer

Although cancer continues to be one of the world's major causes of death, current cancer drugs have many serious side effects. There remains a need for new anticancer agents to overcome these shortcomings. Alternaria is one of the most widespread fungal genera, many species of which produce several classes of metabolites with potential polypharmacological activities. A few quinones and pyrones from Alternaria spp. have proven to exert cytotoxic effects against certain cancer cell lines, but their molecular mode of action is not known. The current study aimed to investigate the potential mechanisms that underlie the anticancer activity of a few selected quinones and pyrones from Alternaria solani and Alternaria alternata by molecular docking and dynamic simulation approaches. The selected metabolites were screened for their binding affinity to Heat shock protein 90 (HSP90), which is a known anticancer drug target. Molecular docking studies have revealed that Macrosporin, Altersolanol B, Fonsecin, and Neoaltenuene have good binding affinities with the target protein and the stabilities of the formed complexes were evaluated through molecular dynamics simulations. By analyzing the Root Mean Square Distance (RMSD), Root Mean Square Fluctuation (RMSF), and Principal Component Analysis (PCA) plots obtained from molecular dynamics simulations, this study shows that the complexes of all 4 lead molecules with target protein are stable over a 100 ns period. Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) calculations were used to compute the binding free energies. The lead molecules were studied using in-silico analysis to determine their drug-likeness based on their Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) and physicochemical properties. The results demonstrate that Macrosporin, Fonsecin, and Neoaltenuene could become promising anticancer molecules that target HSP90.Communicated by Ramaswamy H. Sarma.

PIM1/STAT3 axis: a potential co-targeted therapeutic approach in triple-negative breast cancer

Triple-negative breast cancer lacks an expression of ER, PR, and Her-2, has a poor prognosis, and there are no target therapies available. Therapeutic options to treat TNBC are limited and urgently needed. Strong evidence indicates that molecular signaling pathways have a significant function to regulate biological mechanisms and their abnormal expression endows with the development of cancer. PIM kinase is overexpressed in various human cancers including TNBC which is regulated by various signaling pathways that are crucial for cancer cell proliferation and survival and also make PIM kinase as an attractive drug target. One of the targets of the STAT3 signaling pathway is PIM1 that plays a key role in tumor progression and transformation. In this review, we accumulate the current scenario of the PIM-STAT3 axis that provides insights into the PIM1 and STAT3 inhibitors which can be developed as potential co-inhibitors as prospective anticancer agents.

Naphthoquinone as a New Chemical Scaffold for Leishmanicidal Inhibitors of Leishmania GSK-3

More than 1 billion people live in areas endemic for leishmaniasis, which is a relevant threat for public health worldwide. Due to the inadequate treatments, there is an urgent need to develop novel alternative drugs and to validate new targets to fight this disease. One appealing approach is the selective inhibition of protein kinases (PKs), enzymes involved in a wide range of processes along the life cycle of Leishmania. Several PKs, including glycogen synthase kinase 3 (GSK-3), have been validated as essential for this parasite by genetic or pharmacological methods. Recently, novel chemical scaffolds have been uncovered as Leishmania GSK-3 inhibitors with antiparasitic activity. In order to find new inhibitors of this enzyme, a virtual screening of our in-house chemical library was carried out on the structure of the Leishmania GSK-3. The virtual hits identified were experimentally assayed both for leishmanicidal activity and for in vitro inhibition of the enzyme. The best hits have a quinone scaffold. Their optimization through a medicinal chemistry approach led to a set of new compounds, provided a frame to establish biochemical and antiparasitic structure–activity relationships, and delivered molecules with an improved selectivity index. Altogether, this study paves the way for a systemic search of this class of inhibitors for further development as potential leishmanicidal drugs.

Structure-Based Virtual Screening and De Novo Design of PIM1 Inhibitors with Anticancer Activity from Natural Products

BACKGROUND

the proviral insertion site of Moloney murine leukemia (PIM) 1 kinase has served as a therapeutic target for various human cancers due to the enhancement of cell proliferation and the inhibition of apoptosis.

METHODS

to identify effective PIM1 kinase inhibitors, structure-based virtual screening of natural products of plant origin and de novo design were carried out using the protein-ligand binding free energy function improved by introducing an adequate dehydration energy term.

RESULTS

as a consequence of subsequent enzyme inhibition assays, four classes of PIM1 kinase inhibitors were discovered, with the biochemical potency ranging from low-micromolar to sub-micromolar levels. The results of extensive docking simulations showed that the inhibitory activity stemmed from the formation of multiple hydrogen bonds in combination with hydrophobic interactions in the ATP-binding site. Optimization of the biochemical potency by chemical modifications of the 2-benzylidenebenzofuran-3(2H)-one scaffold led to the discovery of several nanomolar inhibitors with antiproliferative activities against human breast cancer cell lines.

CONCLUSIONS

these new PIM1 kinase inhibitors are anticipated to serve as a new starting point for the development of anticancer medicine.

Synthetically Important Ring-Opening Acylations of Alkoxybenzenes

Cyclic ketones, anhydrides, lactams and lactones are a particular class of molecules that are often used in synthesis, wherein their electrophilic properties are leveraged to enable facile Friedel–Crafts ring openings through nucleophilic attack at the carbonyl sp2 centre. The use of electron-rich alkoxybenzenes as nucleophiles has also become important since the discovery of the Friedel–Crafts reaction. As a result, various isomeric alkoxybenzenes are used for preparing starting materials in target-oriented syntheses. This review covers the instances of different alkoxybenzenes that are used as nucleophiles in ring-opening acylations with carbonyl-containing cyclic electrophiles, for the construction of important building blocks for multistep transformations. This review summarizes the ring-opening functionalization of three- to seven-membered molecular rings with alkoxybenzenes in a Friedel–Crafts fashion. Sometimes the rings need subtle or considerable activation by the help of Lewis acid(s), followed by nucleophilic attack. This review is aimed to be a summary of the important acylations of electron-rich alkoxybenzenes by nucleophilic ring-opening of cyclic molecules. The works cited employ a wide range of conditions and differently substituted substrates for target-oriented syntheses.

1 Introduction and Scope

2 Arenes for Acylative Ring Opening

2.1 Three-Membered Rings: Ring Opening of Oxirane-2,3-dione

2.2 Four-Membered Rings

2.2.1 Ring Opening of Cyclobutanones

2.2.2 Ring Opening of β-Lactams

2.2.3 Ring Opening of β-Lactone

2.3 Five-Membered Rings

2.3.1 Ring Opening of Phthalimides

2.3.2 Ring Opening of γ-Lactones

2.3.3 Ring Opening of Anhydrides

2.4 Six-Membered Rings

2.5 Seven-Membered Rings

3 Conclusion

Off-target toxicity is a common mechanism of action of cancer drugs undergoing clinical trials

Ninety-seven percent of drug-indication pairs that are tested in clinical trials in oncology never advance to receive U.S. Food and Drug Administration approval. While lack of efficacy and dose-limiting toxicities are the most common causes of trial failure, the reason(s) why so many new drugs encounter these problems is not well understood. Using CRISPR-Cas9 mutagenesis, we investigated a set of cancer drugs and drug targets in various stages of clinical testing. We show that-contrary to previous reports obtained predominantly with RNA interference and small-molecule inhibitors-the proteins ostensibly targeted by these drugs are nonessential for cancer cell proliferation. Moreover, the efficacy of each drug that we tested was unaffected by the loss of its putative target, indicating that these compounds kill cells via off-target effects. By applying a genetic target-deconvolution strategy, we found that the mischaracterized anticancer agent OTS964 is actually a potent inhibitor of the cyclin-dependent kinase CDK11 and that multiple cancer types are addicted to CDK11 expression. We suggest that stringent genetic validation of the mechanism of action of cancer drugs in the preclinical setting may decrease the number of therapies tested in human patients that fail to provide any clinical benefit.

PIM kinase inhibition: co-targeted therapeutic approaches in prostate cancer

PIM kinases have been shown to play a role in prostate cancer development and progression, as well as in some of the hallmarks of cancer, especially proliferation and apoptosis. Their upregulation in prostate cancer has been correlated with decreased patient overall survival and therapy resistance. Initial efforts to inhibit PIM with monotherapies have been hampered by compensatory upregulation of other pathways and drug toxicity, and as such, it has been suggested that co-targeting PIM with other treatment approaches may permit lower doses and be a more viable option in the clinic. Here, we present the rationale and basis for co-targeting PIM with inhibitors of PI3K/mTOR/AKT, JAK/STAT, MYC, stemness, and RNA Polymerase I transcription, along with other therapies, including androgen deprivation, radiotherapy, chemotherapy, and immunotherapy. Such combined approaches could potentially be used as neoadjuvant therapies, limiting the development of resistance to treatments or sensitizing cells to other therapeutics. To determine which drugs should be combined with PIM inhibitors for each patient, it will be key to develop companion diagnostics that predict response to each co-targeted option, hopefully providing a personalized medicine pathway for subsets of prostate cancer patients in the future.

Identification of New Mono/Dihydroxynaphthoquinone as Lead Agents That Inhibit the Growth of Refractive and Triple-Negative Breast Cancer Cell Lines

Human epidermal growth factor receptor 2 (HER2) is overexpressed in nearly 20-30% of breast cancers and is associated with metastasis resulting in poor patient survival and high recurrence. The dual EGFR/HER2 kinase inhibitor lapatinib has shown promising clinical results, but its limitations have also led to the resistance and activation of tumor survival pathways. Following our previous investigation of quinones as HER2 kinase inhibitors, we synthesized several naphthoquinone derivatives that significantly inhibited breast tumor cells expressing HER2 and trastuzumab-resistant HER2 oncogenic isoform, HER2Δ16. Two of these compounds were shown to be more effective than lapatinib at the inhibition of HER2 autophosphorylation of Y1248. Compounds 7 (5,8-dihydroxy-2-methylnaphthalene-1,4-dione) and 9 (2-(bromomethyl)-5,8-dihydroxynaphthalene-1,4-dione) inhibited HER2-expressing MCF-7 cells (IC50 0.29 and 1.76 μM, respectively) and HER2Δ16-expressing MCF-7 cells (IC50 0.51 and 1.76 μM, respectively). Compound 7 was also shown to promote cell death in multiple refractory breast cancer cell lines with IC50 values ranging from 0.12 to 2.92 μM. These compounds can function as lead compounds for the design of a new series of nonquinonoid structural compounds that can maintain a similar inhibition profile.

Synthetic Method to Form 2,2'-Bis(naphthoquinone) Compounds

We have discovered a transition-metal-free approach to the synthesis of 2,2'-bis(naphthoquinones) using a Diels-Alder reaction of conjugated ketene silyl acetals with benzoquinone. Its monomer analogue can also be synthesized by simply increasing the equivalents of benzoquinone.