P-glycoprotein possesses A 1,4-dihydropyridine-selective drug acceptor site which is alloserically coupled to a vinca-alkaloid-selective binding site

doi:10.1016/0006-291X(92)92404-L

Biochemical and Biophysical Research Communications

Volume 188, Issue 1, 15 October 1992, Pages 440-445

https://doi.org/10.1016/0006-291X(92)92404-L Get rights and content

Abstract

[³H]Vinblastine bound with high affinity to surface membranes prepared from H69/LX4 cells which express P-glycoprotein (P-gp) and as a consequence are multidrug resistant (MDR). The KD was 9.8 ± 1.5 nM and density of sites 31.2 ± 8.6 pmol/mg of protein. [³H]Vinblastine binding was inhibited by cytotoxics and agents known to reverse MDR. 1,4-Dihydropyridine MDR reversing agents including nicardipine and nifedipine accelerated the dissociation of [³H]vinblastine from P-gp indicating a negative heterotropic allosteric effect. Cyclosporin A, vincristine and actinomycin D did not alter [³H]vinblastine dissociation kinetics. It is concluded that P-gp possesses at least two allosterically coupled drug acceptor Sites, receptor site-1 that is selective for vinca alkaloids and cyclosporin A, and receptor site-2 that is selective for 1,4-dihydropyridines.

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Erratum: Discovery of a non-toxic [1,2,4]triazolo[1,5-a]pyrimidin-7-one (WS-10) that modulates ABCB1-mediated multidrug resistance (MDR) (Bioorganic & Medicinal Chemistry (2018) 26(18) (5006–5017)(S0968089618306692)(10.1016/j.bmc.2018.08.021))
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Multidrug resistance (MDR) has been shown to reduce the effectiveness of chemotherapy. Strategies to overcoming MDR have been widely explored in the last decades, leading to a generation of numerous small molecules targeting ABC and MRP transporters. Among the ABC family, ABCB1 plays key roles in the development of drug resistance and is the most well studied. In this work, we report the discovery of non-toxic [1,2,4]triazolo[1,5-a]pyrimidin-7-one (WS-10) from our structurally diverse in-house compound collection that selectively modulates ABCB1-mediated multidrug resistance. WS-10 enhanced the intracellular accumulation of paclitaxel in SW620/Ad300 cells, but did not affect the expression of ABCB1 Protein and ABCB1 localization. The cellular thermal shift assay (CETSA) showed that WS-10 was able to bind to ABCB1, which could be responsible for the reversal effect of WS-10 toward paclitaxel and doxorubicin in SW620/Ad300 cells. Docking simulations were performed to show the possible binding modes of WS-10 within ABCB1 transporter. To conclude, WS-10 could be used as a template for designing new ABCB1 modulators to overcome ABCB1-mediated multidrug resistance.
Discovery of a non-toxic [1,2,4]triazolo[1,5-a]pyrimidin-7-one (WS-10) that modulates ABCB1-mediated multidrug resistance (MDR)
2018, Bioorganic and Medicinal Chemistry
Citation Excerpt :
The ABC transporters utilize the energy generated by ATP hydrolysis to transport various substrates across cellular membranes, therefore leading to elevated drug efflux in cancer cells.5,6 The most well studied ABC transporter in humans is ABCB1 (also known as P-gp/MDR1), which has been found to be essential in mediating the efflux of chemotherapeutic drugs like paclitaxel.7,8 It is believed that the inhibitors of transporters which either decrease the expression of ABC proteins or inhibit the efflux function of ABC transporters could enhance chemosensitivity toward multidrug resistant cancer cells.9
Multidrug resistance (MDR) has been shown to reduce the effectiveness of chemotherapy. Strategies to overcoming MDR have been widely explored in the last decades, leading to a generation of numerous small molecules targeting ABC and MRP transporters. Among the ABC family, ABCB1 plays key roles in the development of drug resistance and is the most well studied. In this work, we report the discovery of a non-toxic [1,2,4]triazolo[1,5-a]pyrimidin-7-one (WS-10) from our structurally diverse in-house compound collection that selectively modulates ABCB1-mediated multidrug resistance. WS-10 enhanced the intracellular accumulation of paclitaxel in SW620/Ad300 cells, but did not affect the expression of ABCB1 Protein and ABCB1 localization. The cellular thermal shift assay (CETSA) showed that WS-10 was able to bind to ABCB1, which could be responsible for the reversal effect of WS-10 toward paclitaxel and doxorubicin in SW620/Ad300 cells. Docking simulations were performed to show the possible binding modes of WS-10 within ABCB1 transporter. To conclude, WS-10 could be used as a template for designing new ABCB1 modulators to overcome ABCB1-mediated multidrug resistance.
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Indeed, multi-drug resistance (MDR) is a significant obstacle to effective chemotherapy. The overexpression of ATP-binding cassette (ABC) membrane transporters is a principal cause of enhanced cytotoxic drug efflux and treatment failure in various types of cancers. At cellular level, the pumps of ABC family regulate the transportation of numerous substances including drugs in and out of the cells. In past, the overexpression of ABC pumps suggested a well-known mechanism of drug resistance in cancers as well as infectious diseases. In oncology, the search for new compounds for the inhibition of these hyperactive ABC pumps either genetically or functionally, growing interest to reverse multi-drug resistance and increase chemotherapeutic effects. Several ABC pump inhibitor/modulators has been explored to address the cancer associated MDR. However, the clinical results are still disappointing and conventional chemotherapies are constantly failed in successful eradication of MDR tumors. In this context, the structural and functional understanding of different ATP pumps is most important. In this concise review, we elaborated basic crystal structure of ABC transporter proteins as well as its critical elements such as different domains, motifs as well as some important amino acids which are responsible for ATP binding and drug efflux as well as demonstrated an ATP-switch model employed by various ABC membrane transporters. Furthermore, we briefly summarized different newly identified MDR inhibitors/modulators, deployed alone or in combination with cytotoxic agents to deal with MDR in different types of cancers.
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Citation Excerpt :
The compounds chosen in the present investigation are more discerning in their binding sites and their characteristics of binding to P-gp indicate a single class of site for each. Vinblastine and nicardipine exhibit a complex allosteric interaction on P-gp and their binding sites are clearly distinct from a pharmacological perspective [7,40]. Moreover, the two contact residues identified in the present investigation (T769 and M197) are spatially separated and a molecular model for P-gp (PDB4m1m) predicts a separation of approximately 33 Å.
The multidrug resistance P-glycoprotein (P-gp) is characterised by the ability to bind and/or transport an astonishing array of drugs. This poly-specificity is imparted by at least four pharmacologically distinct binding sites within the transmembrane domain. Whether or not these sites are spatially distinct has remained unclear. Biochemical and structural investigations have implicated a central cavity as the likely location for the binding sites. In the present investigation, a number of contact residues that are involved in drug binding were identified through biochemical assays using purified, reconstituted P-gp. Drugs were selected to represent each of the four pharmacologically distinct sites. Contact residues important in rhodamine123 binding were identified in the central cavity of P-gp. However, contact residues for the binding of vinblastine, paclitaxel and nicardipine were located at the lipid-protein interface rather than the central cavity. A key residue (F978) within the central cavity is believed to be involved in coupling drug binding to nucleotide hydrolysis. Data observed in this investigation suggest the presence of spatially distinct drug binding sites connecting through to a single translocation pore in the central cavity.

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P-glycoprotein possesses A 1,4-dihydropyridine-selective drug acceptor site which is alloserically coupled to a vinca-alkaloid-selective binding site

Abstract

J Biol Chem

J. Biol Chem

J Biol Chem

Cancer Res

Annu Rev Biochem

Br J Cancer

Br. J. Cancer

Am. J. Physiol

Biochem Prarmacol