Design and synthesis of new 2-anilinoquinolines bearing N -methylpicolinamide moiety as potential antiproliferative agents

Discovery of novel 4-trifluoromethyl-2-anilinoquinoline derivatives as potential anti-cancer agents targeting SGK1

Given the critical necessity for the development of more potent anti-cancer drugs, a series of novel compounds incorporating trifluoromethyl groups within the privileged 2-anilinoquinoline scaffold was designed, synthesized, and subjected to biological evaluation through a pharmacophore hybridization strategy. Upon evaluating the in vitro anti-cancer characteristics of the target compounds, it became clear that compound 8b, which contains a (4-(piperazin-1-yl)phenyl)amino substitution at the 2-position of the quinoline skeleton, displayed superior efficacy against four cancer cell lines by inducing apoptosis and cell cycle arrest. Following research conducted in a PC3 xenograft mouse model, it was found that compound 8b exhibited significant anti-cancer efficacy while demonstrating minimal toxicity. Additionally, the analysis of a 217-kinase panel pinpointed SGK1 as a potential target for this compound class with anti-cancer capabilities. This finding was further verified through molecular docking analysis and cellular thermal shift assays. To conclude, our results emphasize that compound 8b can be used as a lead compound for the development of anti-cancer drugs that target SGK1.

Overcoming the imatinib-resistant BCR-ABL mutants with new ureidobenzothiazole chemotypes endowed with potent and broad-spectrum anticancer activity

The design of kinase inhibitors targeting the oncogenic kinase BCR-ABL constitutes a promising paradigm for treating chronic myeloid leukaemia (CML). Nevertheless, the efficacy of imatinib, the first FDA-approved targeted therapy for CML, is curbed by the emergence of resistance. Herein, we report the identification of the 2-methoxyphenyl ureidobenzothiazole AK-HW-90 (2b) as a potent pan-BCR-ABL inhibitor against imatinib-resistant mutants, particularly T315I. A concise array of six compounds 2a-f was designed based on our previously reported benzothiazole lead AKE-5l to improve its BCR-ABL^T315I inhibitory activity. Replacing the 6-oxypicolinamide moiety of AKE-5l with o-methoxyphenyl and changing the propyl spacer with phenyl afforded 2a and AK-HW-90 (2b) with IC₅₀ values of 2.0 and 0.65 nM against BCR-ABL^T315I, respectively. AK-HW-90 showed superior anticancer potency to imatinib against multiple cancer cells (NCI), including leukaemia K-562. The obtained outcomes offer AK-HW-90 as a promising candidate for the treatment of CML and other types of cancer.

Discovery of New Quinolone-Based Diarylamides as Potent B-RAFV600E/C-RAF Kinase Inhibitors Endowed with Promising In Vitro Anticancer Activity

The emergence of cancer resistance to targeted therapy represents a significant challenge in cancer treatment. Therefore, identifying new anticancer candidates, particularly those addressing oncogenic mutants, is an urgent medical demand. A campaign of structural modifications has been conducted to further optimize our previously reported 2-anilinoquinoline-diarylamides conjugate VII as a B-RAFV600E/C-RAF inhibitor. Considering the incorporation of a methylene bridge between the terminal phenyl and cyclic diamine, focused quinoline-based arylamides have been tailored, synthesized, and biologically evaluated. Among them, the 5/6-hydroxyquinolines 17b and 18a stood out as the most potent members, with IC₅₀ values of 0.128 µM, 0.114 µM against B-RAF^V600E, and 0.0653 µM, 0.0676 µM against C-RAF. Most importantly, 17b elicited remarkable inhibitory potency against the clinically resistant B-RAF^V600K mutant with an IC₅₀ value of 0.0616 µM. The putative binding mode of 17b and 18a were studied by molecular docking and molecular dynamics (MD). Moreover, the antiproliferative activity of all target compounds has been examined over a panel of NCI-60 human cancer cell lines. In agreement with cell-free assays, the designed compounds exerted superior anticancer impact over the lead quinoline VII against all cell lines at a 10 µM dose. Notably, both 17b and 18b showed highly potent antiproliferative activity against melanoma cell lines with growth percent under -90% (SK-MEL-29, SK-MEL-5, and UACC-62) at a single dose, while 17b maintained potency with GI₅₀ values of 1.60-1.89 µM against melanoma cell lines. Taken together, 17b, a promising B-RAF^V600E/V600K and C-RAF kinase inhibitor, may serve as a valuable candidate in the arsenal of anticancer chemotherapeutics.

Recent developments in mitogen activated protein kinase inhibitors as potential anticancer agents

The mitogen activated protein kinase (MAPK) belongs to group of kinase that links the extracellular stimuli to intracellular response. The MAPK signalling pathway (RAS-RAF-MEK-ERK) involved in different pathological conditions like cancer, caused due to genetic or any other factor such as physical or environmental. Many studies have been conducted on the pathological view of MAPK cascade and its associated element like RAS, RAF, MEK, ERK or its isoforms, and still the research is going on particularly with respect to its activation, regulation and inhibition. The MAPK signalling pathway has become the area of research to identify new target for the management of cancer. A number of heterocyclics are key to fight with the cancer associated with these enzymes thus give some hope in the management of cancer by inhibiting MAPK cascade. In the present article, we have focussed on MAPK signalling pathway and role of different heterocyclic scaffolds bearing nitrogen, sulphur and oxygen and about their potential to block MAPK signalling pathway. The heterocyclics are gaining importance due to high potency and selectivity with less off-target effects against different targets involved in the MAPK signalling pathway. We have tried to cover recent advancements in the MAPK signalling pathway inhibitors with an aim to get better understanding of the mechanism of action of the compounds. Several compounds in the preclinical and clinical studies have been thoroughly dealt with. In addition to the synthetic compounds, a significant number of natural products containing heterocyclic moieties as MAPK signalling pathway inhibitors have been put together. The structure activity relationship along with docking studies have been discussed to apprehend the mechanistic studies of various compounds that will ultimately help to design and develop more MAPK signalling pathway inhibitors.

2-Anilinoquinoline based arylamides as broad spectrum anticancer agents with B-RAFV600E/C-RAF kinase inhibitory effects: Design, synthesis, in vitro cell-based and oncogenic kinase assessments

Prompted by the urgent demand for identification of new anticancer agents with improved potency and efficacy, a new series of arylamides incorporating the privileged 2-anilinoquinoline scaffold has been designed, synthesized, and biologically assessed. Aiming at extensive evaluation of the target compounds' potency and spectrum, a panel of 60 clinically important cancer cell lines representing nine cancer types has been used. Compounds 9a and 9c, with piperazine substituted phenyl ring, emerged as the most active members surpassing the anticancer potencies of the FDA-approved drug imatinib. They elicited sub-micromolar or one-digit micromolar GI₅₀ values over the majority of tested cancer cells including multidrug resistant (MDR) cells like colon HCT-15, renal TK-10 and UO-31, and ovarian NCI/ADR-RES. In vitro mechanistic study showed that compounds 9a and 9c could trigger morphological changes, apoptosis and cell cycle arrest in HCT-116 colon cancer cells. Besides, compound 9c altered microtubule polymerization pattern in a similar fashion to paclitaxel. Kinase screening of 9c disclosed its inhibitory activity over B-RAF^V600E and C-RAF kinases with IC₅₀ values of 0.888 μM and 0.229 μM, respectively. Taken together, the current report presents compounds 9a and 9c as promising broad-spectrum potent anticancer candidates, which could be considered for further development of new anticancer drugs.

Structural Basis for Design of New Purine-Based Inhibitors Targeting the Hydrophobic Binding Pocket of Hsp90

Inhibition of the molecular chaperone heat shock protein 90 (Hsp90) represents a promising approach for cancer treatment. BIIB021 is a highly potent Hsp90 inhibitor with remarkable anticancer activity; however, its clinical application is limited by lack of potency and response. In this study, we aimed to investigate the impact of replacing the hydrophobic moiety of BIIB021, 4-methoxy-3,5-dimethylpyridine, with various five-membered ring structures on the binding to Hsp90. A focused array of N⁷/N⁹-substituted purines, featuring aromatic and non-aromatic rings, was designed, considering the size of hydrophobic pocket B in Hsp90 to obtain insights into their binding modes within the ATP binding site of Hsp90 in terms of π–π stacking interactions in pocket B as well as outer α-helix 4 configurations. The target molecules were synthesized and evaluated for their Hsp90α inhibitory activity in cell-free assays. Among the tested compounds, the isoxazole derivatives 6b and 6c, and the sole six-membered derivative 14 showed favorable Hsp90α inhibitory activity, with IC₅₀ values of 1.76 µM, 0.203 µM, and 1.00 µM, respectively. Furthermore, compound 14 elicited promising anticancer activity against MCF-7, SK-BR-3, and HCT116 cell lines. The X-ray structures of compounds 4b, 6b, 6c, 8, and 14 bound to the N-terminal domain of Hsp90 were determined in order to understand the obtained results and to acquire additional structural insights, which might enable further optimization of BIIB021.

Quinoline-Based Molecules Targeting c-Met, EGF, and VEGF Receptors and the Proteins Involved in Related Carcinogenic Pathways

The quinoline ring system has long been known as a versatile nucleus in the design and synthesis of biologically active compounds. Currently, more than one hundred quinoline compounds have been approved in therapy as antimicrobial, local anaesthetic, antipsychotic, and anticancer drugs. In drug discovery, indeed, over the last few years, an increase in the publication of papers and patents about quinoline derivatives possessing antiproliferative properties has been observed. This trend can be justified by the versatility and accessibility of the quinoline scaffold, from which new derivatives can be easily designed and synthesized. Within the numerous quinoline small molecules developed as antiproliferative drugs, this review is focused on compounds effective on c-Met, VEGF (vascular endothelial growth factor), and EGF (epidermal growth factor) receptors, pivotal targets for the activation of important carcinogenic pathways (Ras/Raf/MEK and PI3K/AkT/mTOR). These signalling cascades are closely connected and regulate the survival processes in the cell, such as proliferation, apoptosis, differentiation, and angiogenesis. The antiproliferative biological data of remarkable quinoline compounds have been analysed, confirming the pivotal importance of this ring system in the efficacy of several approved drugs. Furthermore, in view of an SAR (structure-activity relationship) study, the most recurrent ligand–protein interactions of the reviewed molecules are summarized.

Novel 5,6-disubstituted pyrrolo[2,3-d]pyrimidine derivatives as broad spectrum antiproliferative agents: Synthesis, cell based assays, kinase profile and molecular docking study

Two new series of 5-subtituted and 5,6-disubstituted pyrrolo[2,3-d]pyrimidine octamides (4a-o and 6a-g) and their corresponding free amines 5a-m and 7a-g have been synthesized and biologically evaluated for their antiproliferative activity against three human cancer cell lines. The 5,6-disubstituted octamides 6d-g as well as the amine derivative 7b have shown the best anticancer activity with single digit micromolar GI₅₀ values over the tested cancer cells, and low cytotoxic effects (GI₅₀ > 10.0 µM) against HFF-1 normal cell. A structure activity relationship (SAR) study has been established and disclosed that terminal octamide moiety at C2 as well as disubstitution with fluorobenzyl piperazines at C5 and C6 of pyrrolo[2,3-d]pyrimidine are the key structural features prerequisite for best antiproliferative activity. Moreover, the most active member 6f was tested for its antiproliferative activity over a panel of 60 cancer cell lines at NCI, and exhibited distinct broad spectrum anticancer activity with submicromolar GI₅₀ and TGI values over multiple cancer cells. Kinase profile of compound 6f over 53 oncogenic kinases at 10 µM concentration showed its highly selective inhibitory activity towards FGFR4, Tie2 and TrkA kinases. The observed activity of 6f against TrkA (IC₅₀ = 2.25 µM), FGFR4 (IC₅₀ = 6.71 µM) and Tie2 (IC₅₀ = 6.84 µM) was explained by molecular docking study, which also proposed that 6f may be a type III kinase inhibitor, binding to an allosteric site rather than kinase hinge region. Overall, compound 6f may serve as a promising anticancer lead compound that could be further optimized for development of potent anticancer agents.