Structure-activity relationships of 2, 4-disubstituted pyrimidines as dual ERα/VEGFR-2 ligands with anti-breast cancer activity

Dual-target inhibitors based on ERα: Novel therapeutic approaches for endocrine resistant breast cancer

Estrogen receptor alpha (ERα), a nuclear transcription factor, is a well-validated therapeutic target for more than 70% of all breast cancers (BCs). Antagonizing ERα either by selective estrogen receptor modulators (SERMs) or selective estrogen receptor degraders (SERDs) forms the foundation of endocrine therapy and has achieved great success in the treatment of ERα positive (ERα+) BCs. Unfortunately, despite initial effectiveness, endocrine resistance eventually emerges in up to 30% of ERα+ BC patients and remains a significant medical challenge. Several mechanisms implicated in endocrine resistance have been extensively studied, including aberrantly activated growth factor receptors and downstream signaling pathways. Hence, the crosstalk between ERα and another oncogenic signaling has led to surge of interest to develop combination therapies and dual-target single agents. This review briefly introduces the synergisms between ERα and another anticancer target and summarizes the recent advances of ERα-based dual-targeting inhibitors from a medicinal chemistry perspective. Accordingly, their rational design strategies, structure-activity relationships (SARs) and biological activities are also dissected to provide some perspectives on future directions for ERα-based dual target drug discovery in BC therapy.

Synthesis of novel pyrimido[4,5-b]quinoline derivatives as dual EGFR/HER2 inhibitors as anticancer agents

A series of novel N-aryl-5-aryl-6,7,8,9-tetrahydropyrimido[4,5-b]quinolin-4-amines 4a-4l was synthesized as potential anticancer agents through Dimroth rearrangement reaction of intermediates 3a-3c. Pyrimido[4,5-b]quinolines 4a-4l showed promising activity against the Michigan Cancer Foundation-7 (MCF-7) cell line, compared with lapatinib as the reference drug. Compounds 4d, 4h, 4i, and 4l demonstrated higher cytotoxic activity than lapatinib, with IC50 values of 2.67, 6.82, 4.31, and 1.62 µM, respectively. Compounds 4d, 4i, and 4l showed promising epidermal growth factor receptor (EGFR) inhibition with IC50 values of 0.065, 0.116, and 0.052 µM, respectively. These compounds were subjected to human epidermal growth factor receptor 2 (HER2) inhibition and showed IC50 values of 0.09, 0.164, and 0.055 µM, respectively. Compounds 4d, 4i, and 4l are good candidates as dual EGFR/HER2 inhibitors. The most active compound, 4l, was subjected to cell-cycle analysis and induced cell-cycle arrest at the S phase. Compound 4l induced apoptosis 60-fold compared with control untreated MCF-7 cells. 4l can inhibit cancer metastasis. It reduced MCF-7 cell infiltration and metastasis by 45% compared with control untreated cells.

Synthesis of novel pyrimido[4,5-b]quinolines as potential anticancer agents and HER2 inhibitors

A series of N-arylpyrimido[4,5-b]quinolines 3a-e and 2-aryl-2,3-dihydropyrimido[4,5-b]quinoline-4(1H)-ones 5a-e was designed and synthesized as potential anticancer agents against breast cancer. Compounds 3e, 5a, 5b, 5d, and 5e showed promising activity against the MCF-7 cell line. Among them, compound 5b was the most active with IC50 of 1.67 μM. Compound 5b promoted apoptosis and induced cell cycle arrest at S phase. 5b increased the level of pro-apoptotic proteins p53, Bax, and caspase-7 and inhibited the anti-apoptotic protein Bcl-2. Furthermore, all the synthesized compounds were docked into the crystal structure of HER2 (PBD: 3 pp0). Compounds 3e, 5a, 5b, 5d, and 5e showed good energy scores and binding modes. Finally, Compound 5b was evaluated on the HER2 assay and revealed good inhibition with IC50 of 0.073 μM.

An overview of imidazole and its analogues as potent anticancer agents

The quest for novel, physiologically active imidazoles remains an exciting topic of research among medicinal chemists. The imidazole ring is a five-membered aromatic heterocycle that is found in both natural and synthesized compounds. Multiple anticancer drug classes are currently available on the market, but concerns including toxicity, limited efficacy and solubility have lowered the overall therapeutic index. Therefore, the hunt for new potential chemotherapeutic agents persists. The development of imidazole as a reliable and safer alternative to anticancer treatment is generating much attention among experts. Tubulin or microtubule polymerization inhibition and changes in the structure and function of DNA, VEGF, topoisomerase, kinases, histone deacetylases and certain other proteins that affect gene expression are among the putative targets.

New Indazol-Pyrimidine-Based Derivatives as Selective Anticancer Agents: Design, Synthesis, and In Silico Studies

In this research study, the authors successfully synthesized potent new anticancer agents derived from indazol-pyrimidine. All the prepared compounds were tested for in vitro cell line inhibitory activity against three different cancerous cell lines. Results demonstrated that five of the novel compounds-4f, 4i, 4a, 4g, and 4d-possessed significant cytotoxic inhibitory activity against the MCF-7 cell line, with IC₅₀ values of 1.629, 1.841, 2.958, 4.680, and 4.798 μM, respectively, compared to the reference drug with an IC₅₀ value of 8.029 μM, thus demonstrating promising suppression power. Compounds 4i, 4g, 4e, 4d, and 4a showed effective cytotoxic activity stronger than the standard against Caco2 cells. Moreover, compounds 4a and 4i exhibited potent antiproliferative activity against the A549 cell line that was stronger than the reference drug. The most active products, 4f and 4i, werr e further examined for their mechanism of action. It turns out that they were capable of activating caspase-3/7 and, therefore, inducing apoptosis. However, produced a higher safety profile than the reference drug, towards the normal cells (MCF10a). Furthermore, the dynamic nature, binding interaction, and protein-ligand stability were explored through a Molecular Dynamics (MD) simulation study. Various analysis parameters (RMSD, RMSF, RoG, and SASA) from the MD simulation trajectory have suggested the stability of the compounds during the 20 ns MD simulation study. In silico ADMET results revealed that the synthesized compounds had low toxicity, good solubility, and an absorption profile since they met Lipinski's rule of five and Veber's rule. The present research highlights the potential of derivatives with indazole scaffolds bearing pyrimidine as a lead compound for designing anticancer agents.

Recent development of multi-target VEGFR-2 inhibitors for the cancer therapy

Vascular epidermal growth factor receptor-2 (VEGFR-2), as an important tyrosine transmembrane protein, plays an important role in regulating endothelial cell proliferation and migration, regulating angiogenesis and other biological functions. VEGFR-2 is aberrantly expressed in many malignant tumors, and it is also related to the occurrence, development, and growth of tumors and drug resistance. Currently, there are nine VEGFR-2 targeted inhibitors approved by US.FDA for clinical use as anticancer drugs. Due to the limited clinical efficacy and potential toxicity of VEGFR inhibitors, it is necessary to develop new strategies to improve the clinical efficacy of VEGFR inhibitors. The development of multitarget therapy, especially dual-target therapy, has become a hot research field of cancer therapy, which may provide an effective strategy with higher therapeutic efficacy, pharmacokinetic advantages and low toxicity. Many groups have reported that the therapeutic effects could be improved by simultaneously inhibiting VEGFR-2 and other targets, such as EGFR, c-Met, BRAF, HDAC, etc. Therefore, VEGFR-2 inhibitors with multi-targeting capabilities have been considered to be promising and effective anticancer agents for cancer therapy. In this work, we reviewed the structure and biological functions of VEGFR-2, and summarized the drug discovery strategies, and inhibitory activities of VEGFR-2 inhibitors with multi-targeting capabilities reported in recent years. This work might provide the reference for the development of VEGFR-2 inhibitors with multi-targeting capabilities as novel anticancer agents.

Oxazolinyl derivatives of androst-16-ene as inhibitors of CYP17A1 activity and prostate carcinoma cells proliferation: Effects of substituents in oxazolinyl moiety

Steroid derivatives modified with nitrogen containing heterocycles are known to inhibit activity of steroidogenic enzymes, decrease proliferation of cancer cells and attract attention as promising anticancer agents. Specifically, 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-4',5'-dihydro-1',3'-oxazole 1a potently inhibited proliferation of prostate carcinoma cells. In this study we synthesized and investigated five new derivatives of 3β-hydroxyandrosta-5,16-diene comprising 4'-methyl or 4'-phenyl substituted oxazolinyl cycle 1 (b-f). Docking of compounds 1 (a-f) to CYP17A1 active site revealed that the presence of substitutents at C4' atom in oxazoline cycle, as well as C4' atom configuration, significantly affect docking poses of compounds in the complexes with enzyme. Testing of compounds 1 (a-f) as CYP17A1 inhibitors revealed that the only compound 1a, comprising unsubstituted oxazolinyl moiety, demonstrated strong inhibitory activity, while other compounds 1 (b-f) were slightly active or non active. Compounds 1 (a-f) efficiently decreased growth and proliferation of prostate carcinoma LNCaP and PC-3 cells at 96 h incubation; the effect of compound 1a was the most powerful. Compound 1a efficiently stimulated apoptosis and caused PC-3 cells death, that was demonstrated by a direct comparison of pro-apoptotic effects of compound 1a and abiraterone.

Symmetry dual functional pyrimidine-BODIPY probes for imaging targeting and activity study

Nondestructive diagnosis of tumor has always been the goal of scientists. Fluorescent dyes have become the rising star in the field of cancer diagnosis because of their excellent characteristics. Therefore, in this work, fluorescence probes d-Y-B and dO-Y-B with anti-tumor activity were constructed by introducing pyrimidine groups with high anti-tumor activity using fluorescence dye BODIPY as parent nucleus. The modified BODIPY group in the structure had the advantage of fluorescent dye, ensuring the strong fluorescence and photosensitivity of the target compound. That ethylenediamine acts as a bridge with two -NH- groups to increase molecular hydrogen bonding, and can bind firmly to multiple proteins. Co-localization of the target compounds d-Y-B and dO-Y-B with the hoechst dye for labeling living cells showed that these compounds had high biocompatibility and photostability for localization to HeLa cells. In vivo imaging in mice can realize specific localization and real-time visualization of tumor cells. The results of cytotoxicity experiments in vitro and computer software simulating molecular docking confirmed the potential of the target compounds as an anticancer agents. The bifunctional probe realized visualization of cancer cells in mice, and can kill cancer cells by anti-proliferation, which may provide a direction for future anticancer drug development.

Recent progress on vascular endothelial growth factor receptor inhibitors with dual targeting capabilities for tumor therapy

Vascular endothelial growth factor receptors (VEGFRs) are a family of receptor protein tyrosine kinases that play an important role in the regulation of tumor-induced angiogenesis. Currently, VEGFR inhibitors have been widely used in the treatment of various tumors. However, current VEGFR inhibitors are limited to a certain extent due to limited clinical efficacy and potential toxicity, which hinder their clinical application. Thus, the development of new strategies to improve the clinical outcomes and minimize the toxic effects of VEGFR inhibitors is required. Given the synergistic effect of VEGFR and other therapies in tumor development and progression, VEGFR dual-target inhibitors are becoming an attractive approach due to their favorable pharmacodynamics, low toxicity, and anti-resistant effects. This perspective provides an overview of the development of VEGFR dual-target inhibitors from multiple aspects, including rational target combinations, drug discovery strategies, structure–activity relationships and future directions.

Design, synthesis, and SAR studies of novel 4-methoxyphenyl pyrazole and pyrimidine derivatives as potential dual tyrosine kinase inhibitors targeting both EGFR and VEGFR-2

Guided by the pharmacophoric features of both EGFR and VEGFR-2 antagonists, two novel series of 4-methoxyphenyl pyrazole and pyrimidine derivatives [(4a-c) and (5a-c, 6, 7a-c, 8, 9, 10, 11a,c, 12, 13a-c, 14a-c, and 15a,b)], respectively, were designed and synthesized as dual EGFR/VEGFR-2 inhibitors. Interestingly, compound 12 showed very strong antiproliferative effects towards all the five studied cell lines (HepG-2, MCF-7, MDA-231, HCT-116, and Caco-2) with IC₅₀ values of 3.74, 7.81, 4.85, 2.96, and 9.27 µM, respectively. Also, it achieved the highest inhibitory activities against both EGFR and VEGFR-2 as well (IC₅₀ = 0.071 and 0.098 µM) compared to the two reference drugs, erlotinib (IC₅₀ = 0.063 µM) and sorafenib (IC₅₀ = 0.041 µM), respectively. Moreover, four compounds (4a, 7a, 7c, and 12) were selected for further evaluation through cell cycle analysis and Annexin V-based flow cytometry assay in the HepG-2 cell line. In addition, deep computational studies including molecular docking, physicochemical properties, profiling pharmacokinetics, ADMET studies, and toxicity predictions were performed for the designed compounds to evaluate the prospective drug candidates. Finally, analyzing the structure-activity relationship (SAR) of the new derivatives gives us a lot of interesting promising results which could help medicinal chemists to design more potent drug candidates soon as well.

Fused and Substituted Pyrimidine Derivatives as Profound Anti-Cancer Agents

The rationale behind drug design is the strategic utilization of heterocyclic fragments with specific physicochemical properties to form molecular targeted agents. Among the heterocyclic molecules, pyrimidine has proved to be a privileged pharmacophore for various biological cancer targets. The anti-cancer potential of small molecules with fused and substituted pyrimidines can be enhanced through bioisosteric replacements and altering their ADME parameters. Although several small molecules are used in cancer chemotherapy, oncology therapeutics has various limitations, especially in their routes of administration and their concurrent side effects. Such pernicious effects may be overcome, via selective biological targeting. In this review, the biological targets, to inhibit cancer, have been discussed. The structural activity relationship of fused and substituted pyrimidines was studied. Eco-friendly synthetic approaches for pyrimidine derivatives have also been discussed. This review will give an insight to scientists and researchers of medicinal chemistry discipline to design small molecules having a pyrimidine scaffold with high anti-cancer potential.

2-Carbamimidoylbenzoic Acid as a New Effective and Available Precursor for the Synthesis of Substituted 2-(Pyrimidin-2-yl)benzoic Acids

A new approach to the synthesis of 2-(pyrimidin-2-yl)benzoic acids based on the ring contraction of the 2-carbamimidoylbenzoic acid [(2-amidinobenzoic) acid] with 1,3-dicarbonyl compounds and their synthetic equivalents has been developed. The intramolecular condensation of the obtained acids with 1,3-dielectrophiles proceeds with the formation of the 4,6-dihydropyrimido[2,1-a]isoindole-4,6-dione system, the pyrrolidone ring of which is easily opened under the action of weak nucleophiles. The reaction of 2-amidinobenzoic acid with chromones, which have an aryloxy group at 3-position does not stop at the step of pyrimidine ring formation and undergoes further spontaneous cyclization into 2-(benzo[4,5]furo[3,2-d]pyrimidin-2-yl)benzoic acids.

Most recent strategies targeting estrogen receptor alpha for the treatment of breast cancer

Breast cancer is the most prominent, frequently diagnosed and leading cause of death among women. Estrogen is an agonist of estrogen receptor alpha (ER-α), expressed in mammary glands and is responsible for initiating many signalling pathways that lead to differentiation and development of breast tissue. Any mutations in these signalling pathways result in irregular growth of mammary tissue, leading to the development of tumour or cancer. All these observations attract the attention of researchers to antagonize ER-α receptor either by developing selective estrogen receptor modulators or by selective estrogen receptor degraders. Therefore, this article provides a brief overview of various factors that are responsible for provoking breast cancer in women and design strategies recently used by the various research groups across the world for antagonizing or demodulating ER-α.

Design, synthesis, biological evaluation, QSAR analysis and molecular modelling of new thiazol-benzimidazoles as EGFR inhibitors

Heterocyclic rings such as thiazole and benzimidazole are considered as privileged structures, since they constitute several FDA-approved drugs for cancer treatment. In this work, a new set of 2-(2-(substituted) hydrazinyl)-4-(1-methyl-1H-benzo[d]imidazol-2-yl) thiazoles 4a-q were designed as epidermal growth factor receptor (EGFR) inhibitors and synthesized using concise synthetic methods. The new target compounds have been evaluated in vitro for their suppression activity against EGFR TK. Compounds 4n, 4h, 4i, 4a and 4d exhibited significant potency in comparison with erlotinib which served as a reference drug (IC50, 71.67-152.59 nM; IC50 erlotinib, 152.59 nM). Furthermore, MTT assay revealed that compounds 4j, 4a, 4f, 4h, 4n produced the most promising cytotoxic potency against the human breast cancer cell line (MCF-7) (IC50; 5.96-11.91 µM; IC50 erlotinib; 4.15 µM). Compound 4a showed promising activity as EGFR TK inhibitor as well as anti-breast cancer agent. In addition, 4a induced apoptotic effect and cell cycle arrest at G2/M phase preventing the mitotic cycle in MCF-7 cells. Moreover, 4a upregulated the oncogenic parameters; caspase-3, p53, Bax/Bcl-2 as well as it inhibited the level of PARP-1 enzyme. QSAR study was carried out for the new derivatives and it revealed the goodness of the models. Furthermore, molecular docking studies represented the binding modes of the promising compounds in the active pocket of EGFR.

A new class of 1,3,5-triazine-based selective estrogen receptor degraders (SERDs): Lead optimization, molecular docking and dynamic simulation

Selective estrogen receptor degrader (SERD) that acts as not only ER antagonist, but also ER degrader, would be useful for the treatment for drug-resistance ER+ breast cancer. However, most of currently available SERD candidates involve very limited molecular scaffolds and are still in clinical trials. In this study, we introduced a 1,3,5-triazine ring into a homobibenzyl motif extracted from amounts of ER ligands and synthesized sixteen SERDs bearing acrylic acid or acrylic amide side chains that possess both ERα antagonism and degradation properties. And all compounds were screened for their anti-proliferative activity against ER+ MCF-7 and Ishikawa cell lines. Among them, compound XHA1614 displayed potent growth inhibition activity against MCF-7 and Ishikawa cells with IC₅₀ values of 3.15 μM and 3.11 μM, respectively. Moreover, XHA1614 could dramatically degrade ER level at 1 nM in a Western blotting assay and afforded an outstanding antagonistic activity via suppressing the expression of progesterone receptor messenger RNA in MCF-7 cells in a RT-PCR assay. Further molecular docking and dynamic simulation on properly selected derivative furnished insights into its binding profile within ERα. Our findings suggest that the 1,3,5-triazine core was a feasible alternative to currently reported SERD scaffold, and provide information that will be useful for further development of promising SERDs candidates for breast cancer therapies.

Rational approaches of drug design for the development of selective estrogen receptor modulators (SERMs), implicated in breast cancer

Drug discovery and development have gained momentum due to the rational drug design by engaging computational tools and bioinformatics methodologies. Bioisosteric replacements and hybrid molecular approaches are the other inventive processes, used by medicinal chemists for the desired modifications of leads for clinical drug candidates. SERMs, ought to produce inhibitory activity in breast, uterus and agonist activity in other tissues, are beneficial for estrogen-like actions. ER subtypes α and β are hormone dependent modulators of intracellular signaling and gene expression, and development of ER selective ligands could be an effective approach for treatment of breast cancer. This report has critically investigated the possible designing considerations of SERMs, their in silico interactions, and potent pharmacophore generation approaches viz. indole, restricted benzothiophene [3, 2-b] indole, carborane, xanthendione, combretastatin A-4, organometallic heterocycles, OBHS-SAHA hybrids, benzopyranones, tetrahydroisoquinolines, Dig G derivatives and their specifications in drug design and development, to rationally improve the understanding in drug discovery. This also includes various strategies for the development of dual inhibitors for the management of antiestrogenic resistance.

Design and synthesis of novel steroidal imidazoles as dual inhibitors of AR/CYP17 for the treatment of prostate cancer

Both AR and CYP17 are important targets for blocking androgen signaling, and it has been accepted that multifunctional drugs have a low risk of drug resistance in the treatment of cancer. Thus, herein a series of steroidal imidazoles were designed, synthesized and evaluated as dual AR/CYP17 ligands. Several compounds displayed good biological profiles in both enzymatic and cellular assays. SAR studies showed that introducing oximino at the C-3 position of steroidal scaffold is beneficial to the enhancement of AR antagonistic activity. Among these compounds, the most potent compound 13a exhibited the best AR inhibition (IC₅₀ = 0.5 μM) that was 27-fold increase compared with the hit compound 5 as well as comparable CYP17 inhibition (IC₅₀ = 11 μM). Additionally, 13a displayed promising anti-proliferative effects on LNCap cell lines with the IC₅₀ value of 23 μM which was superior to positive control Flutamide (IC₅₀ = 28 μM). Furthermore, the docking results of 13a revealed that the oxygen atom at the position of C-3 connected to the heme of CYP17, which may be helpful for its satisfactory dual-target inhibition. In summary, this study provides an efficient strategy for multi-targeting drug discovery in the treatment of prostate cancer.

Novel camphor-based pyrimidine derivatives induced cancer cell death through a ROS-mediated mitochondrial apoptosis pathway

A series of novel camphor-based pyrimidine derivatives (3a–3x) have been synthesized; their structures were determined by using conventional methods and compound 3f was further confirmed through single crystal XRD analysis. The cytotoxic activity of the target compounds against a panel of human normal (GES-1) and cancer cell lines (MDA-MB-231, RPMI-8226, A549) was evaluated by MTS assay. Here we found that compound 3f exhibited the strongest anti-tumor activity, comparable to that of etoposide, and had much lower cytotoxicity to normal GES-1 cells (IC₅₀ > 50 μM) than the reference drug (IC₅₀ = 8.89 μM). Subsequent mechanism studies in MDA-MB-231 cells revealed that compound 3f caused G0/G1 phase arrest and apoptosis in a dose dependent manner. Moreover, the loss of mitochondrial membrane potential and enhancement of cellular ROS levels were also observed upon 3f treatment, which indicated that 3f exerted cytotoxic activity by a ROS-mediated mitochondrial apoptosis pathway. This result was confirmed by a significant increase in the expression of pro-apoptotic proteins Bax, cytochrome C and caspase-3, and downregulation of anti-apoptosis protein Bcl-2. Overall, 3f can be adopted for further investigation in the development of antitumor agents based on natural products.

A series of novel camphor-based pyrimidine derivatives were synthesized and characterized. We found the compound 3f exhibited strongest anti-tumor activity via ROS-mediated mitochondrial apoptosis pathway.