Indomethacin induces apoptosis via a MRP1-dependent mechanism in doxorubicin-resistant small-cell lung cancer cells overexpressing MRP1

Abstract

Small-cell lung cancers (SCLCs) initially respond to chemotherapy, but are often resistant at recurrence. The non-steroidal anti-inflammatory drug indomethacin is an inhibitor of multidrug resistance protein 1 (MRP1) function. The doxorubicin-resistant MRP1-overexpressing human SCLC cell line GLC 4 -Adr was highly sensitive for indomethacin compared with the parental doxorubicin-sensitive line GLC 4 . The purpose of this study was to analyse the relationship between hypersensitivity to indomethacin and MRP1 overexpression. The experimental design involved analysis of the effect of MRP1 downregulation on indomethacininduced cell survival and apoptosis in GLC 4 -Adr and GLC 4 , using siRNA. In addition the effect of indomethacin on glutathione levels and mitochondrial membrane potential was investigated. Small interfering RNAs directed against MRP1 reduced MRP1 mRNA levels twofold and reduced efflux pump function of MRP1, which was reflected by a 1.8-fold higher accumulation of MRP1 substrate carboxyfluorescein, in si-MRP1 versus si-Luciferase-transfected GLC 4 -Adr cells. Multidrug resistance protein 1 downregulation decreased initial high apoptosis levels 2-fold in GLC 4 -Adr after indomethacin treatment for 24 h, and increased cell survival (IC 50 ) from 22.8±2.6 to 30.4±5.1 mM following continuous indomethacin exposure. Multidrug resistance protein 1 downregulation had no effect on apoptosis in GLC 4 or on glutathione levels in both lines. Although indomethacin (20 mM) for 2 h decreased glutathione levels by 31.5% in GLC 4 -Adr, complete depletion of cellular glutathione by L-buthionine (S,R)-sulphoximine only resulted in a small increase in indomethacin-induced apoptosis in GLC 4 -Adr, demonstrating that a reduced cellular glutathione level is not the primary cause of indomethacin-induced apoptosis. Indomethacin exposure decreased mitochondrial membrane potential in GLC 4 -Adr cells, suggesting activation of the mitochondrial apoptosis pathway. Indomethacin induces apoptosis in a doxorubicin-resistant SCLC cell line through an MRP1-dependent mechanism. This may have implications for the treatment of patients with MRP1-overexpressing tumours.

Isolation of a Small‐Molecule Inhibitor of the Antiapoptotic Protein Bcl‐xL from a DNA‐Encoded Chemical Library

“…[37][38][39] Different mechanisms have been proposed for the induction of indomethacin-mediated apoptosis, including the inhibition of multidrug-resistance protein 1 function [40] and the suppression of the STATs/Bcl-xL signaling pathway. [41] It is becoming increasingly clear that cytotoxic agents and anti-inflammatory drugs may simultaneously inhibit multiple targets.…”

An overview of cancer multidrug resistance: a still unsolved problem

“…Likewise, antiapoptotic roles were also suggested for other ABC-transporters including BCRP [123] . On the other hand, it has been reported that the non-steroidal anti-inflammatory drug indomethacin, an inhibitor of MRP1, induces apoptosis in MRP1-expressing lung cancer cells through an MRP1-dependent mechanism [124] . Thus, possible pro-apoptotic features of ABCtransporters should also be considered.…”

3d metal complexes with meloxicam as therapeutic agents in the fight against human glioblastoma multiforme and cervical carcinoma

“…[15] Numerous studies have suggested that aspirin and/or other NSAIDs can be effective in the prevention and/or treatment of malignancies, such as cancers of the colon, [16] breast, [17,18] lung, [19] pancreas, [20] prostate, [21,22] ovarium, [23] squamous cell carcinoma and melanoma, [24] etc. Different NSAIDs have been reported to inhibit the growth and survival of cell lines established from a wide variety of cancers, including gastric cancer, [25,26] cancers of the colon, [27] lung, [28] urinary bladder, [29] osteosarcoma, [30] etc.…”