ko-143 and Neoplasms

Chemotherapy is an important means of cancer treatment. However, overexpression of efflux transporters (including but not limited to P-gp and BCRP) can lead to resistance to cancer chemotherapy. Multiple-target inhibitors of efflux transporter can be overcome the resistance and improve the oral bioavailability of chemotherapy drugs. Therefore, we designed and synthesized a series of phthalazinone ring derivatives (1-20) with different aromatic heterocycles substituents on the amide bond for dual inhibition of P-gp and BCRP. Most target compounds significantly increased the accumulation of P-gp substrates in the chemo-resistant cancer cell lines by inhibiting the efflux of transporters. Compound 19 in particular showed stronger MDR reversal compared to Gefitinib and Verapamil, and comparable to that of the BCRP inhibitor Ko143. In addition, compound 19 improved intestinal absorption of paclitaxel (PTX) and enhanced the bioavailability of the orally administered drug in vivo.

Topics: ATP Binding Cassette Transporter, Subfamily G, Member 2; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Neoplasm Proteins; Neoplasms; Paclitaxel

Several members of the ABC transporter superfamily play a decisive role in the development of multidrug resistance (MDR) in cancer. One of these MDR associated efflux transporters is ABCG2. One way to overcome this MDR is the coadministration of potent inhibitors of ABCG2. In this study, we identified novel inhibitors containing a 2,4,6-substituted quinazoline scaffold. Introduction of a 6-nitro function led to extraordinarily potent compounds that were highly selective for ABCG2 and also able to reverse the MDR toward the chemotherapeutic drugs SN-38 and mitoxantrone. The binding of substrate Hoechst 33342 and the two potent inhibitors 31 and 41 which differ in their mechanism of inhibition was rationalized using the recently published cryo-EM structures of ABCG2. For a better understanding of the interaction between the inhibitors and ABCG2, additional investigations regarding the ATPase activity, the interaction with Hoechst 33342, and with the conformational sensitive 5D3 antibody were carried out.

Topics: Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily G, Member 2; Benzimidazoles; Cell Proliferation; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Molecular Structure; Neoplasm Proteins; Neoplasms; Protein Conformation; Quinazolines; Structure-Activity Relationship; Tumor Cells, Cultured

The breast cancer resistance protein (ABCG2) transports chemotherapeutic drugs out of cells, which makes it a major player in mediating multidrug resistance (MDR) of cancer cells. To overcome this mechanism, inhibitors of ABCG2 can be used. Only a few potent and selective ABCG2 inhibitors have been discovered, i.e., fumitremorgin C (FTC), Ko143, and the alkaloid harmine, which contain a tetrahydro-β-carboline or β-carboline backbone, respectively. However, toxicity and or instability prevent their use in vivo. Therefore, there is a need for further potent inhibitors. We synthesized and pharmacologically investigated 37 tetrahydro-β-carboline derivatives. The inhibitory activity of two compounds (51, 52) is comparable to that of Ko143, and they are selective for ABCG2 over ABCB1. Furthermore, they are able to reverse the ABCG2-mediated resistance toward SN-38 and inhibit the ATPase activity. The cytotoxicity data show that their inhibitory effect is substantially higher than their toxicity.

Topics: Adenosine Triphosphatases; Animals; Antineoplastic Agents, Phytogenic; ATP Binding Cassette Transporter, Subfamily G, Member 2; Camptothecin; Carbolines; Cell Line; Dogs; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Female; Humans; Irinotecan; Neoplasm Proteins; Neoplasms

We are interested in developing novel natural product-derived P-gp inhibitors to reverse cancer drug resistance. Here, we have synthesized 55 novel derivatives of methylated epigallocatechin (EGC), gallocatechin (GC), and dihydromyricetin (DHM). Three EGC derivatives (23, 35, and 36) and three GC derivatives (50, 51, and 53) are significantly better than epigallocatechin gallate (EGCG) with a relative fold (RF) ranging from 31.4 to 53.6. The effective concentration (EC50) of 23 and 51 ranges from 102 to 195 nM. Compounds 23 and 51 are noncytotoxic to fibroblasts with IC50 > 100 μM. Compound 23 is specific for P-gp without modulating activity toward MRP1 or BCRP. Compounds 23 and 51 are non-P-gp substrates. Important pharmacophores for P-gp modulation were identified. In summary, methylated EGC and GC derivatives represent a new class of potent, specific, noncytotoxic, and nonsubstrate P-gp modulators.

Topics: Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Catechin; Cell Proliferation; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Flavonols; Humans; Methylation; Models, Molecular; Molecular Structure; Neoplasm Proteins; Neoplasms; Structure-Activity Relationship; Tumor Cells, Cultured