Spiroindoline quinazolinedione derivatives as inhibitors of P-glycoprotein: potential agents for overcoming multidrug resistance in cancer therapy.

Abstract

Multidrug resistance (MDR) presents a major challenge for effectiveness of chemotherapy. This study investigates the effectiveness of spiroindoline quinazolinediones in reversing MDR mediated by P-glycoprotein (P-gp) overexpression in cancer cells. A series of synthesized hybrid spiro[indoline-3,2'-quinazoline]-2,4'(3'H)-dione derivatives (compounds 5a-5l) were analyzed for their ability to enhance rhodamine 123 (Rhd123) accumulation in the MES-SA/DX5 cell line using flow cytometry. The MTT assay was also employed to evaluate the compounds' effectiveness in reversing drug resistance. Additionally, docking studies and molecular dynamics simulations were conducted to investigate the interaction of these compounds with the P-gp transporter. The Rhd123 accumulation assay in MDR cancer cells revealed that most compounds, in particular 5f, 5g, 5h, 5i, 5j, 5k, and 5l, exhibited significant potential as P-gp inhibitors. Among the tested derivatives, compounds 5g and 5l demonstrated the best effects, and increased Rhd123 accumulation up to 12.9 times compared to untreated cells. Additionally, compounds 5f through 5 l bearing methylbenzyl (5f), benzyl (5g), pentyl (5 ), p-bromobenzyl (5i), p-chlorobenzyl (5j), dichlorobenzyl (5k), and tert-butylbenzyl (5l) substituents on the isatin ring effectively restored sensitivity to doxorubicin at their non-toxic concentrations in resistant MES-SA/DX5 cells. Among these, compound 5l at 5 μM exhibited the highest inhibitory potential, and lowered doxorubicin's IC₅₀ value 10.1 times compared to control. Moreover, in silico investigation identified the potential interactions of test compounds with critical residues of P-gp involved in its efflux function. Our study suggests that the synthesized spiroindoline quinazolinediones may have high potentials as agents capable of reversing MDR in cancer cells.