The multi-targeted tyrosine kinase inhibitor SKLB610 resensitizes ABCG2-overexpressing multidrug-resistant cancer cells to chemotherapeutic drugs

Exploring the Potential of Pyridine Carboxylic Acid Isomers to Discover New Enzyme Inhibitors

Pyridine carboxylic acid isomers - picolinic acid, nicotinic acid, and isonicotinic acid - have historically resulted in a plethora of drugs against tuberculosis, cancer, diabetes, Alzheimer's, angina, dementia, depression, allergy, respiratory acidosis, psoriasis, acne, hypertension, hyperlipidemia, HIV/AIDS (specifically HIV-1), among others. Despite the large number of therapeutic agents derived from these isomers, the research involving these scaffolds is still exceptionally active. The current surge in enzyme inhibitory activities by the compounds derived from them has further created space for the discovery of new drug candidates. This review focuses on the medicinal relevance of these isomers by analyzing structure-activity relationships (SARs) and highlighting emerging trends from patents filed over the last decade. Notably, pharmaceutical giants like Bayer, Bristol-Myers Squibb, Novartis, Curis, and Aurigene have developed enzyme inhibitors based on these scaffolds with nanomolar potency. The role of these isomers in the development of antiviral agents, including protease inhibitors, is also discussed. Overall, this review brings to the readers, a pragmatic opportunity to comprehend the recent literature, highlighting the scaffolds' importance in the design of new enzyme inhibitors. Furthermore, it discusses the structure-activity relationship of pyridine carboxylic acid-derived compounds and highlights the current patenting trends in medicinal chemistry.

c-MET tyrosine kinase inhibitors reverse multidrug resistance in breast cancer cells by targeting ABCG2 transporter

BACKGROUND

Overcoming multidrug resistance (MDR), which is often caused by the overexpression of ATP binding cassette (ABC) transporters in cancer cells remains a major challenge for cancer treatment. Receptor tyrosine kinase inhibitors have demonstrated potential in reversing MDR. This study aimed to investigate the effects of c-MET RTKIs on the reversal of MDR induced by ABCG2 in breast cancer cells.

METHODS

MTT assay was employed to assess antiproliferative activity of c-MET inhibitors, including cabozantinib, crizotinib, and PHA665752. The accumulation of the fluorescent probe mitoxantrone was evaluated by flow cytometry. The drug-drug interaction in combination treatments was analyzed using CalcuSyn software.

RESULTS

The combination of cabozantinib, crizotinib, and PHA665752 with mitoxantrone resulted in synergistic effects in MDR cells. This was demonstrated by the mean CI values of 0.32 ± 0.07, 0.53 ± 0.05, and 0.59 ± 0.03, respectively. In the same cells, c-MET inhibitors enhanced the accumulation of mitoxantrone, with accumulation ratios ranging from 1.6 to 3.8, while no change was found in parental MCF-7 cells. Computational analysis revealed that the drug-binding region of ABCG2 transporters could be a viable target for these compounds.

CONCLUSION

c-MET inhibitors hold potential as effective agents for reversing MDR in ABCG2-medicated drug-resistant cancer cells.

c-MET tyrosine kinase inhibitors reverse drug resistance mediated by the ATP-binding cassette transporter B1 (ABCB1) in cancer cells

This study investigated the potential of MET kinase inhibitors, cabozantinib, crizotinib, and PHA665752, in reversing multidrug resistance (MDR) mediated by ABCB1 in cancer cells. The accumulation of the fluorescent probe, Rhodamine 123, was assessed using flow cytometry and fluorescence microscopy in MDR MES-SA/DX5 and parental cells. The growth inhibitory activity of MET inhibitors as monotherapies and in combination with chemotherapeutic drugs was evaluated by MTT assay. CalcuSyn software was used to analyze the combination index (CI) as an index of drug-drug interaction in combination treatments. Results showed that at concentrations of 5, and 25 μM, c-MET inhibitors significantly increased Rhodamine 123 accumulation in MDR cells, with ratios up to 17.8 compared to control cells, while exhibiting no effect in parental cells. Additionally, the combination of c-MET inhibitors with the chemotherapeutic agent doxorubicin synergistically enhanced cytotoxicity in MDR cells, as evidenced by combination index (CI) values of 0.54 ± 0.08, 0.69 ± 0.1, and 0.85 ± 0.07 for cabozantinib, crizotinib, and PHA665752, respectively. While all three c-MET inhibitors stimulated ABCB1 ATPase activity in different manners at certain concentrations, PHA-665752 suppressed it at high concentration. In silico analysis also suggested that the transmembrane domains (TMD) of ABCB1 transporters could be considered potential target for these agents. Our results suggest that c-MET inhibitors can serve as promising MDR reversal agents in ABCB1-medicated drug-resistant cancer cells.

The colony-stimulating factor-1 receptor inhibitor edicotinib counteracts multidrug resistance in cancer cells by inhibiting ABCG2-mediated drug efflux

Chemotherapy treatment faces a major obstacle with the emergence of multidrug resistance (MDR), often attributed to the elevated expression of ATP-binding cassette (ABC) transporters such as ABCG2 and ABCB1 in cancer cells. These transporters hinder the efficacy of cytotoxic drugs via ATP hydrolysis-dependent efflux, leading to diminished intracellular drug levels. The scarcity of approved treatments for multidrug resistant cancers necessitates exploration of alternative strategies, including drug repositioning of molecular targeted agents to counteract ABCG2-mediated MDR in multidrug-resistant cancer cells. This study investigates the potential of edicotinib, a selective colony-stimulating factor-1 receptor (CSF-1R) tyrosine kinase inhibitor that is currently undergoing clinical trials for various diseases, to reverse MDR in ABCG2-overexpressing cancer cells. Our findings reveal that by attenuating the drug-efflux function of ABCG2 without altering its expression, edicotinib improves drug-induced apoptosis and reverses MDR in ABCG2-overexpressing multidrug-resistant cancer cells at non-toxic concentrations. Through ATPase activity analysis and molecular docking, potential interaction sites for edicotinib on ABCG2 were identified. These results underscore an additional pharmacological benefit of edicotinib against ABCG2 activity, suggesting its potential incorporation into combination therapies for patients with ABCG2-overexpressing tumors. Further research is warranted to validate these findings and explore their clinical implications.

Foretinib, a c-MET receptor tyrosine kinase inhibitor, tackles multidrug resistance in cancer cells by inhibiting ABCB1 and ABCG2 transporters

BACKGROUND

ABC transporter-mediated multidrug resistance (MDR) remains a major obstacle for cancer pharmacological treatment. Some tyrosine kinase inhibitors (TKIs) have been shown to reverse MDR. The present study was designed to evaluate for the first time whether foretinib, a multitargeted TKI, can circumvent ABCB1 and ABCG2-mediated MDR in treatment-resistant cancer models.

METHODS

Accumulation of fluorescent substrates of ABCB1 and ABCG2 in ABCB1-overexpressing MES-SA/DX5 and ABCG2-overexpressing MCF-7/MX and their parenteral cells was evaluated by flow cytometry. The growth inhibitory activity of single and combination therapy of foretinib and chemotherapeutic drugs on MDR cells was examined by MTT assay. Analysis of combined interaction effects was performed using CalcuSyn software.

RESULTS

It was firstly proved that foretinib increased the intracellular accumulation of rhodamine 123 and mitoxantrone in MES-SA/DX5 and MCF-7/MX cancer cells, with accumulation ratios of 12 and 2.2 at 25 μM concentration, respectively. However, it did not affect the accumulation of fluorescent substrates in the parental cells. Moreover, foretinib synergistically improved the cytotoxic effects of doxorubicin and mitoxantrone. The means of combination index (CI) values at fraction affected (Fa) values of 0.5, 0.75, and 0.9 were 0.64 ± 0.08 and 0.47 ± 0.09, in MES-SA/DX5 and MCF-7/MX cancer cells, respectively. In silico analysis also suggested that the drug-binding domain of ABCB1 and ABCG2 transporters could be considered as potential target for foretinib.

CONCLUSION

Overall, our results suggest that foretinib can target MDR-linked ABCB1 and ABCG2 transporters in clinical cancer therapy.

Evaluation of the FDA-approved kinase inhibitors to uncover the potential repurposing candidates targeting ABC transporters in multidrug-resistant cancer cells: an in silico approach

Multiple drug resistance (MDR) is characterized by the resistance of cancer cells to a broad spectrum of anticancer drugs. The main mechanism underlying the MDR phenotype is the overexpression of ATP-binding cassette (ABC) transporters by promoting active drug efflux from cancer cells. Some small-molecule protein kinase inhibitors have been found to overcome MDR by inhibiting ABC transporters as substrates or modulators. This study investigated the chemical activity of 58 FDA-approved anticancer kinase inhibitors against three multidrug resistance-related proteins. The studied proteins are ATP-Binding Cassette Sub-Family B Member 1 (ABCB1), ATP-Binding Cassette Subfamily C Member 1 (ABCC1), and ATP-binding cassette superfamily G member 2 (ABCG2). The drug-binding domain and ATP binding sites of the proteins were considered the kinase inhibitors' probable target. High-throughput virtual screening and molecular docking were employed to find the hit drugs, and the drugs with the highest binding affinity were further evaluated using the molecular dynamics (MD) simulation. The virtual screening revealed that several kinase inhibitors could be considered potential inhibitors of ABCB1, ABCC1, and ABCG2, among which larotrectinib, entrectinib, and infigratinib showed the highest binding affinity, respectively. Based on the obtained results from MD simulation, these drugs can form strong interactions with the essential residues of the target proteins. In silico investigation revealed that larotrectinib, entrectinib, and infigratinib can target the key residues of the studied proteins. Therefore, these approved kinase inhibitors could be considered potential therapies for MDR cancers by targeting these transporters.Communicated by Ramaswamy H. Sarma.

Advances in the structure, mechanism and targeting of chemoresistance-linked ABC transporters

Cancer cells frequently display intrinsic or acquired resistance to chemically diverse anticancer drugs, limiting therapeutic success. Among the main mechanisms of this multidrug resistance is the overexpression of ATP-binding cassette (ABC) transporters that mediate drug efflux, and, specifically, ABCB1, ABCG2 and ABCC1 are known to cause cancer chemoresistance. High-resolution structures, biophysical and in silico studies have led to tremendous progress in understanding the mechanism of drug transport by these ABC transporters, and several promising therapies, including irradiation-based immune and thermal therapies, and nanomedicine have been used to overcome ABC transporter-mediated cancer chemoresistance. In this Review, we highlight the progress achieved in the past 5 years on the three transporters, ABCB1, ABCG2 and ABCC1, that are known to be of clinical importance. We address the molecular basis of their broad substrate specificity gleaned from structural information and discuss novel approaches to block the function of ABC transporters. Furthermore, genetic modification of ABC transporters by CRISPR-Cas9 and approaches to re-engineer amino acid sequences to change the direction of transport from efflux to import are briefly discussed. We suggest that current information regarding the structure, mechanism and regulation of ABC transporters should be used in clinical trials to improve the efficiency of chemotherapeutics for patients with cancer.

Synthesis and Structure Determination of Substituted Thiazole Derivatives as EGFR/BRAFV600E Dual Inhibitors Endowed with Antiproliferative Activity

2,3,4-trisubstituted thiazoles 3a-i, having a methyl group in position four, were synthesized by the reaction of 1,4-disubstituted thiosemicarbazides with chloroacetone in ethyl acetate/Et₃N at room temperature or in ethanol under reflux. The structures of new compounds were determined using NMR spectroscopy, mass spectrometry, and elemental analyses. Moreover, the structure of compound 3a was unambiguously confirmed with X-ray analysis. The cell viability assay of 3a-i at 50 µM was greater than 87%, and none of the tested substances were cytotoxic. Compounds 3a-i demonstrated good antiproliferative activity, with GI₅₀ values ranging from 37 to 86 nM against the four tested human cancer cell lines, compared to the reference erlotinib, which had a GI₅₀ value of 33 nM. The most potent derivatives were found to be compounds 3a, 3c, 3d, and 3f, with GI₅₀ values ranging from 37 nM to 54 nM. The EGFR-TK and BRAF^V600E inhibitory assays' results matched the antiproliferative assay's results, with the most potent derivatives, as antiproliferative agents, also being the most potent EGFR and BRAF^V600E inhibitors. The docking computations were employed to investigate the docking modes and scores of compounds 3a, 3c, 3d, and 3f toward BRAF^V600E and EGFR. Docking computations demonstrated the good affinity of compound 3f against BRAF^V600E and EGFR, with values of -8.7 and -8.5 kcal/mol, respectively.