Design, synthesis and biological evaluation of stereo- and regioisomers of amino aryl esters as multidrug resistance (MDR) reversers

Abstract

Stereo-and regioisomers of a series of N,N-bis(alkanol)amine aryl ester derivatives have been prepared and studied as multidrug resistance (MDR) modulators. The new compounds contain a 2-(methyl)propyl chain combined with a 3-, 5-or 7-methylenes long chain and carry different aromatic ester portions. Thus, these compounds have a methyl group on the 3-methylenes chain and represent branched homologues of previously studied derivatives. The introduction of the methyl group gives origin to a stereogenic center and consequently to (R) and (S) enantiomers. In the pirarubicin uptake assay on K562/ DOX cell line these compounds showed good activity and efficacy and in many cases enantioselectivity was observed. Docking studies confirmed the influence of the stereocenter on the interaction in the P-gp pocket. The P-gp interaction mechanism and selectivity towards MRP1 and BCRP were also evaluated on MDCK transfected cells overexpressing the three transporters. Almost all these compounds inhibited both P-gp and BCRP, but only derivatives with specific structural characteristics showed MRP1 activity. Moreover, two compounds, (S)-3 and (R)-7, showed the ability to induce collateral sensitivity (CS) against MDR cells. Therefore, these two CS-promoting agents could be considered interesting leads for the development of selective cytotoxic agents for drug-resistant cells.

Insights into P-Glycoprotein Inhibitors: New Inducers of Immunogenic Cell Death

“…We compared Tariquidar, the latest clinically tested Pgp inhibitor [22], and R-3, a N,N-bis(alkanol) amine aryl ester derivative recently synthesized by our group, with an EC 50 for Pgp similar to Tariquidar [23,24]. Tariquidar is reported to bind to the drug binding pocket of the protein, in particular, to the so-called H-site, which is localized within the inner leaflet of the membrane at 10.5 to 14.5Ǻ apart from the membrane surface [32], and it was suggested that it inhibits Pgp pumping from the cytoplasmic face of the membrane [33].…”

“…Tariquidar is a competitive inhibitor of Pgp [30], while R-3 is not [23], although they both reduced the efflux of doxorubicin through Pgp. To clarify why these two inhibitors of Pgp produced such different effects on ICD, we wondered whether they affected the amount of surface Pgp that we previously identified as an inhibitor of CRT immunogenic functions [19].…”

“…Compared to the sensitive counterparts, HT29/DX and A549/DX cells had higher levels of Pgp and MRP1, and MDA-MB-231/DX cells had increased levels of Pgp ( Figure 1A). Neither R-3 nor Tariquidar, used at a concentration comparable to their EC 50 [23,24], increased doxorubicin intracellular content within Pgp-lowly expressing HT29, A549, and MDA-MB-231 cells, but they did so in Pgp-expressing variants ( Figure 1B). Like Tariquidar, R-3 specifically reduced the catalytic activity of Pgp ( Figure 1C), but it did not change the ATPase rate of other ABC transporters involved in doxorubicin efflux, such as MRP1 and BCRP (Supplementary Figure S2).…”

“…Doxorubicin and Tariquidar were purchased by Sigma-Merck. R-3 synthesis and characterization is reported in [23]. The structures of Tariquidar and R-3 are shown in Supplementary Figure S1.…”

“…In the present work, we investigated how Pgp impairs doxorubicin-mediated ICD and if Pgp inhibitors, originally designed as chemosensitizing agents, may be considered as ICD-inducers in combination with doxorubicin. To this aim, we compared Tariquidar and compound R-3-the first-in-class compound of a library of N,N-bis(alkanol)amine aryl ester derivatives recently synthesized by our group [23]-that has an EC 50 for Pgp activity (73 nM) comparable to Tariquidar (74 nM) [24]. We demonstrated that the reduction of Pgp on cell surface but not the simple inhibition of the transporter activity is required to restore doxorubicin-mediated ICD.…”