Discovery of novel selective inhibitors for EGFR-T790M/L858R

1,3,5-Triazine as a promising scaffold in the development of therapeutic agents against breast cancer

1,3,5-Triazine scaffold has garnered considerable interest due to its wide-ranging pharmacological properties, particularly in the field of cancer research. Breast cancer is the most commonly diagnosed cancer among women. Approximately one in eight women will receive a diagnosis of invasive breast cancer during their lifetime. The five-year survival rate for invasive breast cancer is less than 30 %, indicating a need to develop a more effective therapeutic agent targeting breast cancer. This review discusses bioactive 1,3,5-triazines targeting breast cancer cells by the inhibition of different enzymes, which include PI3K, mTOR, EGFR, VEGFR, FAK, CDK, DHFR, DNA topoisomerase, ubiquitin-conjugating enzyme, carbonic anhydrase, and matrix metalloproteinase. The anticancer agent search in some drug discovery programs is based on compound screening for antiproliferative activity. Often, multiple targets contribute to the anticancer effect of 1,3,5-triazines and this approach allows identification of active molecules prior to identification of their targets.

Insights into the computer-aided drug design and discovery based on anthraquinone scaffold for cancer treatment: A systematic review

BACKGROUND

In the search for better anticancer drugs, computer-aided drug design (CADD) techniques play an indispensable role in facilitating the lengthy and costly drug discovery process especially when natural products are involved. Anthraquinone is one of the most widely-recognized natural products with anticancer properties. This review aimed to systematically assess and synthesize evidence on the utilization of CADD techniques centered on the anthraquinone scaffold for cancer treatment.

METHODS

The conduct and reporting of this review were done in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) 2020 guideline. The protocol was registered in the "International prospective register of systematic reviews" database (PROSPERO: CRD42023432904) and also published recently. The search strategy was designed based on the combination of concept 1 "CADD or virtual screening", concept 2 "anthraquinone" and concept 3 "cancer". The search was executed in PubMed, Scopus, Web of Science and MedRxiv on 30 June 2023.

RESULTS

Databases searching retrieved a total of 317 records. After deduplication and applying the eligibility criteria, the final review ended up with 32 articles in which 3 articles were found by citation searching. The CADD methods used in the studies were either structure-based alone (69%) or combined with ligand-based methods via parallel (9%) or sequential (22%) approaches. Molecular docking was performed in all studies, with Glide and AutoDock being the most popular commercial and public software used respectively. Protein data bank was used in most studies to retrieve the crystal structure of the targets of interest while the main ligand databases were PubChem and Zinc. The utilization of in-silico techniques has enabled a deeper dive into the structural, biological and pharmacological properties of anthraquinone derivatives, revealing their remarkable anticancer properties in an all-rounded fashion.

CONCLUSION

By harnessing the power of computational tools and leveraging the natural diversity of anthraquinone compounds, researchers can expedite the development of better drugs to address the unmet medical needs in cancer treatment by improving the treatment outcome for cancer patients.

From Synergy to Monotherapy: Discovery of Novel 2,4,6-Trisubstituted Triazine Hydrazone Derivatives with Potent Antifungal Potency In Vitro and In Vivo

Invasive fungal infections pose a serious threat to public health and are associated with high mortality and incidence rates. The development of novel antifungal agents is urgently needed. Based on hit-to-lead optimization, a series of 2,4,6-trisubstituted triazine hydrazone compounds were designed, synthesized, and biological evaluation was performed, leading to the identification of compound 28 with excellent in vitro synergy (FICI range: 0.094-0.38) and improved monotherapy potency against fluconazole-resistant Candida albicans and Candida auris (MIC range: 1.0-16.0 μg/mL). Moreover, 28 exhibited broad-spectrum antifungal activity against multiple pathogenic strains. Furthermore, 28 could inhibit hyphal and biofilm formation, which may be related to its ability to disrupt the fungal cell wall. Additionally, 28 significantly reduced the CFU in a mouse model of disseminated infection with candidiasis at a dose of 10 mg/kg. Overall, the triazine-based hydrazone compound 28 with low cytotoxicity, hemolysis, and favorable ADME/T characteristics represents a promising lead to further investigation.

In-vitro Evaluation of Triazine Scaffold for Anticancer Drug Development: A Review

INTRODUCTION

The widespread importance of the synthesis and modification of anticancer agents has given rise to many numbers of medicinal chemistry programs. In this regard, triazine derivatives have attracted attention due to their remarkable activity against a wide range of cancer cells. This evaluation covers work reports to define the anticancer activity, the most active synthesized compound for the target, the SAR and, when described, the probable MOA besides similarly considered to deliver complete and target-pointed data for the development of types of anti-tumour medicines of triazine derivatives. Triazine scaffold for the development of anticancer analogues. Triazine can also relate to numerous beneficial targets, and their analogues have auspicious in-vitro and in-vivo anti-tumour activity. Fused molecules can improve efficacy, and drug resistance and diminish side effects, and numerous hybrid molecules are beneath diverse stages of clinical trials, so hybrid derivatives of triazine may offer valuable therapeutic involvement for the dealing of tumours.

OBJECTIVE

The objective of the recent review was to summarize the recent reports on triazine as well as its analogues with respect to its anticancer therapeutic potential.

CONCLUSION

The content of the review would be helpful to update the researchers working towards the synthesis and designing of new molecules for the treatment of various types of cancer disease with the recent molecules that have been produced from the triazine scaffold. Triazine scaffolds based on 1,3,5-triazine considerably boost molecular diversity levels and enable covering chemical space in key medicinal chemistry fields.

Antitumor Activity of s-Triazine Derivatives: A Systematic Review

1,3,5-triazine derivatives, also called s-triazines, are a series of containing-nitrogen heterocyclic compounds that play an important role in anticancer drug design and development. To date, three s-triazine derivatives, including altretamine, gedatolisib, and enasidenib, have already been approved for refractory ovarian cancer, metastatic breast cancer, and leukemia therapy, respectively, demonstrating that the s-triazine core is a useful scaffold for the discovery of novel anticancer drugs. In this review, we mainly focus on s-triazines targeting topoisomerases, tyrosine kinases, phosphoinositide 3-kinases, NADP+-dependent isocitrate dehydrogenases, and cyclin-dependent kinases in diverse signaling pathways, which have been extensively studied. The medicinal chemistry of s-triazine derivatives as anticancer agents was summarized, including discovery, structure optimization, and biological applications. This review will provide a reference to inspire new and original discoveries.

Synthesis, X-ray Structure and Biological Studies of New Self-Assembled Cu(II) Complexes Derived from s-triazine Schiff Base Ligand

The two ligands 2-(1-(2-(4,6-dimorpholino-1,3,5-triazin-2-yl)hydrazono)ethyl)aniline (DMAT) and 2-(1-(2-(4,6-dimorpholino-1,3,5-triazin-2-yl)hydrazono)ethyl)phenol (DMOHT) were used to synthesize three heteroleptic Cu(II) complexes via a self-assembly technique. The structure of the newly synthesized complexes was characterized using elemental analysis, FTIR and X-ray photoelectron spectroscopy (XPS) to be [Cu(DMAT)(H2O)(NO3)]NO3.C2H5OH (1), [Cu(DMOT)(CH3COO)] (2) and [Cu(DMOT)(NO3)] (3). X-ray single-crystal structure of complex 1 revealed a hexa-coordinated Cu(II) ion with one DMAT as a neutral tridentate NNN-chelate, one bidentate nitrate group and one water molecule. In the case of complex 2, the Cu(II) is tetra-coordinated with one DMOT as an anionic tridentate NNO-chelate and one monodentate acetate group. The antimicrobial, antioxidant and anticancer activities of the studied compounds were examined. Complex 1 had the best anticancer activity against the lung carcinoma A-549 cell line (IC50 = 5.94 ± 0.58 µM) when compared to cis-platin (25.01 ± 2.29 µM). The selectivity index (SI) of complex 1 was the highest (6.34) when compared with the free ligands (1.3–1.8), and complexes 2 (0.72) and 3 (2.97). The results suggested that, among those compounds studied, complex 1 is the most promising anticancer agent against the lung carcinoma A-549 cell line. In addition, complex 1 had the highest antioxidant activity (IC50 = 13.34 ± 0.58 µg/mL) which was found to be comparable to the standard ascorbic acid (IC50 = 10.62 ± 0.84 µg/mL). Additionally, complex 2 showedbroad-spectrum antimicrobial action against the microbes studied. The results revealed it to possess the strongest action of all the three complexes against B. subtilis. The MIC values found are 39.06, 39.06 and 78.125 mg/mL for complexes 1–3, respectively.

Building 2D classification models and 3D CoMSIA models on small-molecule inhibitors of both wild-type and T790M/L858R double-mutant EGFR

Epidermal growth factor receptor (EGFR) has received widespread attention because it is an important target for anticancer drug design. Mutations in the EGFR, especially the T790M/L858R double mutation, have made cancer treatment more difficult. We herein built the structure-activity relationship models of small-molecule inhibitors on wild-type and T790M/L858R double-mutant EGFR with a whole dataset of 379 compounds. For 2D classification models, we used ECFP4 fingerprints to build support vector machine and random forest models and used SMILES to build self-attention recurrent neural network models. Each of all six models resulted in an accuracy of above 0.87 and the Matthews correlation coefficient value of above 0.76 on the test set, respectively. We concluded that inhibitors containing anilinoquinoline and methoxy or fluoro phenyl are highly active against wild EGFR. Substructures such as anilinopyrimidine, acrylamide, amino phenyl, methoxy phenyl, and thienopyrimidinyl amide appeared more in highly active inhibitors against double-mutant EGFR. We also used self-organizing map to cluster the inhibitors into six subsets based on ECFP4 fingerprints and analyzed the activity characteristics of different scaffolds in each subset. Among them, three datasets, which are based on pteridin, anilinopyrimidine, and anilinoquinoline scaffold, were selected to build 3D comparative molecular similarity analysis models individually. Models with the leave-one-out coefficient of determination (q²) above 0.65 were selected, and five descriptor types (steric, electrostatic, hydrophobic, donor, and acceptor) were used to study the effects of side chains of inhibitors on the activity against wild-type and mutant-type EGFR.

Synthesis and Anti-Proliferation Activity Evaluation of Novel 2-Chloroquinazoline as Potential EGFR-TK Inhibitors

A novel series of 2-chloroquinazoline derivatives had been synthesized and their anti-proliferation activities against the four EGFR high-expressing cells A549, NCI-H1975, AGS and HepG2 cell lines were evaluated. The preliminary SAR study of the scaffold of new compounds showed that the compounds with a chlorine substituent on R³ had a better anti-proliferation activity than those substituted by hydrogen atom or vinyl group. Among them, 2-chloro-N-[2-chloro-4-(3-chloro-4-fluoroanilino)quinazolin-6-yl]acetamide (10b) had the best activity, and the corresponding IC₅₀ were 3.68, 10.06, 1.73 and 2.04 μM, respectively. And compound 10b had better or equivalent activity against four cell lines than Gefitinib. The activity of the compound 10b on the EGFR enzyme was subsequently tested. The Wound Healing of A549, AGS and HepG2 cells by this compound showed that the compound can inhibit the migration of cancer cells. Finally, the action channel of the compound 10b was supported by western blotting experiments. It provides useful information for the design of EGFR-TK inhibitors.

Synthesis, Anti-proliferative Activity, and Molecular Docking Study of New Series of 1,3-5-Triazine Schiff Base Derivatives

Based on the use of s-triazine as a scaffold, we report here a new series of s-triazine Schiff base derivatives and their anti-proliferative activity against two cancer cell lines: human breast carcinoma (MCF-7), and colon cancer (HCT-116) compared with tamoxifen as a reference compound. Several derivatives exhibited growth inhibition activity in the sub-micromolar range. The results reveal that the s-triazine Schiff base derivatives showed varied activities and that the substituents on the s-triazine core have a great effect on the anti-proliferative activity. Compounds with a piperidino and benzylamino substituent on the s-triazine moiety 4b and 4c were most effective in both cell lines compared to the reference compound used. In addition, compound 4b has a para chlorine atom on the benzylidine residue, demonstrating the most potent activity with IC₅₀ values of 3.29 and 3.64 µM in MCF-7 and HCT-116, respectively. These results indicate that in general, the nature of the substituents on the triazine core and the type of substituent on the benzilyldene ring significantly influenced the anti-proliferative activity. The results obtained from the anti-proliferative activity and the molecular docking study indicate that s-triazine-hydrazone derivatives may be an excellent scaffold for the development of new anti-cancer agents.

Barbiturate- and Thiobarbituarte-Based s-Triazine Hydrazone Derivatives with Promising Antiproliferative Activities

A new class of compounds, which include s-triazine with pyrimidinetrione or thiopyrimidinedione moiety through a hydrazone linkage, were synthesized and characterized. The newly synthesized s-triazine hydrazone derivatives were evaluated in vitro against four cancer cell lines: A549, HepG2, HCT-116, and MCF-7. Several derivatives showed growth inhibition activity in the low microgram range. The results reveal that the barbiturate derivatives showed poor to no activity, while thiobarbiturate derivatives showed better activity than the analogues barbiturate derivatives. The substituents on the s-triazine moiety have a great effect on the antiproliferative activity, where derivatives with the piperidino and diethylamino on the s-triazine ring (5h) showed the highest activity against all of the tested cell lines (IC₅₀ 1.6 ± 0.6, 3.8 ± 0.3, 1.9 ± 0.4, and 1.2± 0.5 μg/mL for the tested cell lines A549, HepG2, HCT-116, and MCF-7, respectively). These results indicate that thiobarbiturates-s-triazine hydrazone derivatives may provide an excellent scaffold for the development of an anticancer drug candidate.

Synthesis and Characterization of New Series of 1,3-5-Triazine Hydrazone Derivatives with Promising Antiproliferative Activity

A new series of s-triazine hydrazone derivatives was prepared based on the reaction of 6-hydrazino-2,4-disubstituted-s-triazine with p-substituted benzaldehyde derivatives using a straightforward synthetic pathway. The antiproliferative activity of all synthesized compounds was evaluated against two human cancer cell lines; breast cancer MCF-7 and colon carcinoma HCT-116 using MTT assay. Among all, 11 compounds have shown strong to moderate antiproliferative activity with IC₅₀ values in the range 1.01–18.20 µM in MCF-7 and 0.97–19.51 µM in HCT-116. The best results were obtained with 4,4’-(6-(2-(pyridin-2-ylmethylene)hydrazinyl)-1,3,5-triazine-2,4-diyl) dimorpholine 11 (IC₅₀ = 1.0 µM and 0.98 µM in MCF-7 and HCT-116 cell lines, respectively). The substituents on the s-triazine core as well as the substituent at the benzylidene moiety have a great effect on the antiproliferative activity. Whereas compounds containing dimorpholino-s-triazine derivatives 8a–e showed more potent antiproliferative in MCF-7 compared to their analogs 7a–f (compounds containing two-piperidine rings), compounds containing one piperidine and one morpholine ring 9a–f showed better IC₅₀ values in the range 10.4–22.2 µM. On the other hand, compounds containing two-piperidine rings 7a–f showed more potent antiproliferative in HCT-116 (IC₅₀ values in the range 8.8–19.5 µM) than their analogs 8a–e and 9a–f.

1,3,5-Triazine Analogs: A Potent Anticancer Scaffold

Background:

This review presents the exhaustive exploration of 1,3,5-triazine scaffold for development of analogs of anticancer drugs, over the last century. In the recent years, striazine moiety has been one of the most studied moiety, showing broad-spectrum pharmacological activities such as antibacterial, antifungal, analgesic, anti-HIV, antileishmanial, antitrypanosomal, antimalarial and antiviral. Nowadays, many boffins are have become interested in novel synthesis of s-triazine derivatives because of low cost and ease of availability.

Methods:

This scaffold has been extensively investigated mainly in the past decade. Many products have been synthesized from different starting materials and these synthetic products possess anticancer potential against various cell lines.

Results:

Many 1,3,5-triazine analogs exhibited significant anticancer activity in various models and cell lines exhibiting different mechanisms. Some analogs have also shown good pharmacokinetic parameters with less IC50 values.

Conclusion:

Various 1,3,5-triazine analogs have shown potent activities and may be regarded as clinical candidates for future anticancer formulations. This review may be helpful to those researchers seeking required information with regard to the drug design and medicinal properties of 1,3,5-triazine derivatives for selected targets. This review may also offer help to find and improve clinically viable anticancer molecules.

Synthesis, X-Ray Crystal Structures, and Preliminary Antiproliferative Activities of New s-Triazine-hydroxybenzylidene Hydrazone Derivatives

We herein report a new small library of Schiff-base compounds that encompasses s-triazine and (2 or 4)-hydroxylbenzylidene derivatives. These compounds were synthesized through a hydrazone linkage connecting both the s-triazine and hydroxybenzylidene derivatives. The synthetic strategy adopted allowed the synthesis of the target compounds with excellent yields and purities as observed from their NMR (1H and 13C) and elemental analysis. Furthermore, 4f, 5b, and 5f were further confirmed by X-ray single crystal diffraction technique. The preliminary antiproliferative activities for the synthesized compounds were tested against two different cancer cell lines including breast cancer (MCF-7) and colon cancer (HCT-116). From the eighteen compounds, which have been examined, only two derivatives having piperidine moiety showed more selectivity against the two cell lines MCF-7 and HCT-116, while the others showed very weak activity. The position of the hydroxyl group in the benzylidine ring and the substituent on the s-triazine moiety has great effect on the activity of the prepared compounds. The IC50 values for the two derivatives 4a and 5a evaluated against breast cancer cells, very close to those for the chemotherapeutic drug cisplatin, are 27 µM (13.3 µg/mL), 17 µM (8.4 µg/mL), and 20 µM (6 µg/mL) for 4a, 5a, and cisplatin, respectively. These results propose the preliminary antiproliferative activity of these two derivatives may deserve further consideration for development of new derivatives as potent anticancer agents.

Design and discovery of novel monastrol-1,3,5-triazines as potent anti-breast cancer agent via attenuating Epidermal Growth Factor Receptor tyrosine kinase

A novel series of hybrid analogues of monastrol-1,3,5-triazine were designed and developed via one-pot synthesis using Bi(NO₃)₃ as a catalyst. Entire compounds were evaluated for their anticancer activity against HeLa (cervical cancer), MCF-7 (breast cancer), HL-60 (Human promyelocytic leukemia), HepG2 (Hepatocellular carcinoma) and MCF 12A (normal epithelial breast cell line) using MTT assay, where they showed highest inhibitory activity against MCF-7. The molecules were also found to be non-toxic to MCF 12A cells. These molecules showed considerable inhibitory percentage against Epidermal Growth Factor Receptor tyrosine kinase (EGFR-TK), in in-vitro assay. Molecular docking study was carried out on the analogs and reference compound (Erlotinib) into the ATP binding site of EGFR-TK domain (PDB ID:1M17) to elucidate vital structural residues necessary for bioactivity. The effect of most active compound 7l was also estimated in-vivo in DMBA induced mammary tumor in female Sprague-Dawley rats. The effect of anti-breast cancer effect of 7l was quantified on the basis of tumour incidence, body weight and tumor volume in DMBA-induced rats. Its effect on biochemical parameters, such as antioxidant status (SOD, CAT, GPX and GSH) and lipid peroxidation was also studied. The compound 7l showed inhibition of EGFR downstream signalling in the western blot analysis.

Structural evidence of quercetin multi-target bioactivity: A reverse virtual screening strategy

The ubiquitous flavonoid quercetin is broadly recognized for showing diverse biological and health-promoting effects, such as anti-cancer, anti-inflammatory and cytoprotective activities. The therapeutic potential of quercetin and similar compounds for preventing such diverse oxidative stress-related pathologies has been generally attributed to their direct antioxidant properties. Nevertheless, accumulated evidence indicates that quercetin is also able to interact with multiple cellular targets influencing the activity of diverse signaling pathways. Even though there are a number of well-established protein targets such as phosphatidylinositol 3 kinase and xanthine oxidase, there remains a lack of a comprehensive knowledge of the potential mechanisms of action of quercetin and its target space. In the present work we adopted a reverse screening strategy based on ligand similarity (SHAFTS) and target structure (idTarget, LIBRA) resulting in a set of predicted protein target candidates. Furthermore, using this method we corroborated a broad array of previously experimentally tested candidates among the predicted targets, supporting the suitability of this screening approach. Notably, all of the predicted target candidates belonged to two main protein families, protein kinases and poly [ADP-ribose] polymerases. They also included key proteins involved at different points within the same signaling pathways or within interconnected signaling pathways, supporting a pleiotropic, multilevel and potentially synergistic mechanism of action of quercetin. In this context we highlight the value of quercetin's broad target profile for its therapeutic potential in diseases like inflammation, neurodegeneration and cancer.

Strategies to overcome acquired resistances conferred by mutations in the kinase domain of EGFR

Deregulation of EGFR is involved in the development of many cancers. The inhibition of EGFR kinase activity has been clinically validated as a promising approach for the treatment of non-small-cell lung cancer (NSCLC). However, all NSCLC patients who initially benefited from first-generation EGFR inhibitors eventually develop drug resistance. A point mutation at the gatekeeper position, T790M in EGFR kinase domain accounts for more than 50% of acquired resistance. Therefore, second- and third-generation EGFR inhibitors have been developed to overcome the resistance conferred by the gatekeeper mutation. This review has highlighted recent advances in overcoming acquired resistance for the development of each generation of EGFR inhibitors along with their potential issues, and urgent quest for the development of new generation of EGFR inhibitors.

iDrug: a web-accessible and interactive drug discovery and design platform

BACKGROUND

The progress in computer-aided drug design (CADD) approaches over the past decades accelerated the early-stage pharmaceutical research. Many powerful standalone tools for CADD have been developed in academia. As programs are developed by various research groups, a consistent user-friendly online graphical working environment, combining computational techniques such as pharmacophore mapping, similarity calculation, scoring, and target identification is needed.

RESULTS

We presented a versatile, user-friendly, and efficient online tool for computer-aided drug design based on pharmacophore and 3D molecular similarity searching. The web interface enables binding sites detection, virtual screening hits identification, and drug targets prediction in an interactive manner through a seamless interface to all adapted packages (e.g., Cavity, PocketV.2, PharmMapper, SHAFTS). Several commercially available compound databases for hit identification and a well-annotated pharmacophore database for drug targets prediction were integrated in iDrug as well. The web interface provides tools for real-time molecular building/editing, converting, displaying, and analyzing. All the customized configurations of the functional modules can be accessed through featured session files provided, which can be saved to the local disk and uploaded to resume or update the history work.

CONCLUSIONS

iDrug is easy to use, and provides a novel, fast and reliable tool for conducting drug design experiments. By using iDrug, various molecular design processing tasks can be submitted and visualized simply in one browser without installing locally any standalone modeling softwares. iDrug is accessible free of charge at http://lilab.ecust.edu.cn/idrug.

In silico identification of EGFR-T790M inhibitors with novel scaffolds: start with extraction of common features

Background

Epidermal growth factor receptor (EGFR) is an attractive therapeutic target for a number of human tumors including non-small cell lung cancer (NSCLC). Most patients with NSCLC and somatic mutations have shown a dramatic initial clinical response to reversible EGFR inhibitors. The clinical efficacy of reversible inhibitors is, however, ultimately limited due to the emergence of drug resistance, which is usually conferred by the EGFR T790M mutation. Importantly, irreversible, synthetic small molecule inhibitors are currently evaluated and some of them have been shown to overcome the acquired resistance that is oftentimes observed in these patients. Thus far, irreversible EGFR inhibitors as a drug class have not received regulatory approval due in part to their poor effectiveness at clinically achievable concentrations. Therefore, there is an urgent need to discover and develop novel, potent irreversible inhibitors against the EGFR T790M mutation.

Material and methods

In the following study, we report a novel “hybrid strategy” to identify irreversible EGFR inhibitors with active scaffolds starting with the identification and extraction of a common chemical reactive feature and a pharmacophore feature. The chemical reactive feature was elucidated by investigating 138 currently known irreversible inhibitors at B3LYP/6-31G(d) level using the density function theory method. The pharmacophore feature was extracted from the same inhibitors using pharmacophore modeling. Based on these unique features, two constraints were set while calibrating the protocols of in silico screening. Compounds bearing these specific features were obtained from the National Cancer Institute diversity database to form our subsequent library. Finally, a structure based virtual screening against the library was conducted using standard protocols validated in our lab.

Results

Twenty-eight candidate compounds that demonstrated antitumor activity and that had novel scaffolds different from commonly known quinazoline/quinoline analogs were obtained. The interaction modes between three representative candidates and our model system are similar to that between the model system and the reference compound T-001, which has previously been reported to be one of the most potent of the 138 irreversible inhibitors.

Conclusion

The hybrid strategy starting with the extraction of common features is an effective approach to design potential irreversible inhibitors with novel scaffolds and therefore to obtain lead molecules in the selection process. These candidates possessing unique scaffolds have a strong likelihood to act as further starting points in the preclinical development of potent irreversible T790M EGFR inhibitors.

βArrestin-1 and Mcl-1 modulate self-renewal growth of cancer stem-like side-population cells in non-small cell lung cancer

Side population (SP) cells have been reported to have properties of cancer stem-like cells (CSCs) in non-small cell lung carcinoma (NSCLC), yet their molecular features have not been fully elucidated. Here we show that, NSCLC-SP cells were enriched in G₀/G­₁ phase of cell cycle, had higher aldehyde dehydrogenase activity as well as higher clonogenic and self-renewing ability compared to main population (MP) cells. Interestingly, SP cells were also able to trans-differentiate into angiogenic tubules in vitro and were highly tumorigenic as compared to MP cells. SP-derived tumors demonstrated the intratumoral heterogeneity comprising of both SP and MP cells, suggesting the self-renewal and differentiation ability of SP cells are manifested in vivo as well. βArrestin-1 (βArr1) is involved in the progression of various cancers including NSCLCs and we find that depletion of βArr1 significantly blocked the SP phenotype; whereas depletion of βArr2 had relatively minor effects. Ectopic expression of βArr1 resulted in increased SP frequency and ABCG2 expression while abrogation of βArr1 expression suppressed the self-renewal growth and expansion of A549 cells. Anti-apoptotic protein Mcl-1 is known to be one of the key regulators of self-renewal of tissue stem cells and is thought to contribute to survival of NSCLC cells. Our experiments show that higher levels of Mcl-1 were expressed in SP cells compared to MP cells at both transcriptional and translational levels. In addition, Obatoclax, a pharmacological inhibitor of Mcl-1, could effectively prevent the self-renewal of both EGFR-inhibitor sensitive and resistant NSCLC cells. In conclusion, our findings suggest that βArr1 and Mcl-1 are involved in the self-renewal and expansion of NSCLC-CSCs and are potential targets for anti-cancer therapy.

Development of a novel class of B-Raf(V600E)-selective inhibitors through virtual screening and hierarchical hit optimization

Oncogenic mutations in critical nodes of cellular signaling pathways have been associated with tumorigenesis and progression. The B-Raf protein kinase, a key hub in the canonical MAPK signaling cascade, is mutated in a broad range of human cancers and especially in malignant melanoma. The most prevalent B-Raf(V600E) mutant exhibits elevated kinase activity and results in constitutive activation of the MAPK pathway, thus making it a promising drug target for cancer therapy. Herein, we describe the development of novel B-Raf(V600E) selective inhibitors via multi-step virtual screening and hierarchical hit optimization. Nine hit compounds with low micromolar IC(50) values were identified as B-Raf(V600E) inhibitors through virtual screening. Subsequent scaffold-based analogue searching and medicinal chemistry efforts significantly improved both the inhibitor potency and oncogene selectivity. In particular, compounds 22f and 22q possess nanomolar IC(50) values with selectivity for B-Raf(V600E)in vitro and exclusive cytotoxicity against B-Raf(V600E) harboring cancer cells.