KS 176

KS176 is a potent and selective inhibitor of the breast cancer resistance protein (BCRP) multidrug transporter (IC50 values are 0.59 and 1.39 μM in Pheo A and Hoechst 33342 assays respectively). Displays no inhibitory activity against P-gp or MRP1. IC50 value: 0.59( in Pheo A assay), 1.39 μM (in Hoechst 33342 assay). Target: BCRP The more detailed information please refer to Compound 9 in the reference.

References:
[1]. Pick A, et al. Specific inhibitors of the breast cancer resistance protein (BCRP). ChemMedChem. 2010 Sep 3;5(9):1498-505.

The biological activity of nonsteroidal vitamin D hormone analogs lacking both the C- and D-rings.[Pubmed:9556055]

J Bone Miner Res. 1998 Apr;13(4):549-58.

1alpha,25-dihydroxyvitamin D is a key calcium-regulating hormone but also displays potent differentiating and antiproliferative activities on many cell types. The structural requirements of this secosteroid hormone have been extensively studied for the A-ring and side chain, whereas relatively little is known about the requirements of the natural CD-ring structure for the vitamin D-like biological activity. We have embarked on a vast program in which derivatives were synthesized and evaluated characterized by profound structural changes in the central C/D-region. This first series of nonsteroidal analogs consists of (1R,3S)-5-((Z,2E)-4-((1S,3S)-3-(4-hydroxy-4-methylpentyl)-1,2,2-++ +trimethylcyclopentyl)-2-butenylidene)-4-methylenecyclohexan e-1,3-diol (KS 176) and derivatives thereof. These analogs are characterized by the absence of normal C- and D-rings and by the presence of an unnatural five-membered ring which we call the E-ring. KS 176 with the otherwise natural side chain structure of 1alpha,25(OH)2D3 has between 10 and 30% of the biological activity of 1alpha,25(OH)2D3 when tested in vitro (prodifferentiating effects on HL-60 and MG-63; antiproliferating activity on MCF-7 and keratinocytes) but has minimal in vivo calcemic effects. Introduction of several side chain modifications created analogs with increased intrinsic noncalcemic biological properties, whereas their calcemic potency remains very low. These data demonstrate that the full CD-rings are not mandatory for the biological activity of 1alpha,25(OH)2D3 since they can be replaced by a new ring structure which generates an appropriate spacing of the A-seco B-rings in relation to the side chain. The biological activity of these nonsteroidal analogs probably involves a classical genomic activation since they are also active in transfection assays using an osteocalcin vitamin D responsive element coupled to a human growth hormone reporter gene.

Specific inhibitors of the breast cancer resistance protein (BCRP).[Pubmed:20632361]

ChemMedChem. 2010 Sep 3;5(9):1498-505.

A new class of specific breast cancer resistance protein (BCRP) inhibitors was identified, showing no inhibition of the ATP binding cassette (ABC) transporters P-gp and MRP1. Some of these modulators inhibit BCRP with high potency; they are only slightly less potent than Ko143 and could serve as promising lead structures for the design of novel effective BCRP inhibitors. These inhibitors are structurally related to tariquidar (XR9576) and belong to a library of multidrug-resistance modulators synthesized by our research group. The absence of the tetrahydroisoquinoline substructure appears to play a crucial role for specificity; we found that the presence of this substructure is not essential for interaction with BCRP. To determine the type of interaction between pheophorbide A and compounds with and without the tetrahydroisoquinoline substructure, various substrate pheophorbide A concentrations were used in enzyme kinetics assays. The resulting data show that these compounds share a noncompetitive-type interaction with pheophorbide A. Experiments with imatinib and pheophorbide A revealed a mixed-type interaction. The combination of imatinib and compounds with and without the tetrahydroisoquinoline substructure resulted in a positive cooperative effect, indicating that imatinib engages a binding site distinct from that of the new compounds on one side and distinct from that of pheophorbide A on the other side as well. The results of this study suggest that the category of BCRP-specific inhibitors, which includes only fumitremorgin C, Ko143 and analogues, and novobiocin needs to be extended by this new class of inhibitors, which possess three key characteristics: specificity, potency, and low toxicity.

KS176 is a potent and selective inhibitor of the breast cancer resistance protein (BCRP) multidrug transporter (IC50 values are 0.59 and 1.39 μM in Pheo A and Hoechst 33342 assays respectively). Displays no inhibitory activity against P-gp or MRP1.

KS 176,1253452-78-6,Natural Products,Multidrug Transporters, buy KS 176 , KS 176 supplier , purchase KS 176 , KS 176 cost , KS 176 manufacturer , order KS 176 , high purity KS 176