Chemotherapeutic drugs induce the activation of proteins associated with tumorigenesis and drug resistance in lower-grade tumor cells

Abstract

Acyl CoA synthetase 4 (ACSL4) is an enzyme participating in the metabolism of arachidonic acid. ATP-binding cassette (ABC) transporters are transmembrane proteins that translocate low molecular weight molecules through ATP hydrolysis.We have previously shown that ACSL4 is involved in resistance to chemotherapeutic agents by regulating the expression of transporters; thus, the objective of this work was to study the effect of chemotherapeutic agents on ACSL4 and resistance mechanisms. The experimental model consisted in the chemotherapeutic challenge of adrenal cancer NCI-H295R and breast cancer MCF-7 cells, two lines characterized by low aggressive phenotypes and low expression of the ACSL4, ABCG2 and ABCC4 proteins. We evaluated cell functionality using proliferation (BrdU) and viability (MTT) assays, and compound exclusion (efflux) using fluorescent Hoechst 33342. ACSL4 and ABC transporters were evaluated by western blot (WB). NCI-H295R cell treatment with doxorubicin (20 nM) and cisplatin (200 nM) increased the expression of ACSL4 (WB-p <0.001), ABCG2 (WB-p <0.001) and ABCC4 (WB-p <0.05). The treatments also improved fluorescent compound exclusion (efflux-p <0.01), an effect reversed by the action of ABGC2 transporter inhibitor KO143. Combined treatments (chemotherapeutic agents and ACSL4 inhibitor) reduced the proliferation of NCI-H295R cells (BrdU-p <0.05). MCF-7 cell treatment with doxorubicin and cisplatin increased the expression of ACSL4 (WB-p <0.001) and ABCG2 (WB-p <0.05) and the phosphorylation of pAKT (WB-p <0.05) and pS6 (WB-p <0.01), components of the AKT/mTOR pathway. These results are in line with our previous observation that ACSL4 regulates ABGC2 expression through the regulation of the AKT/mTOR pathway. Therefore, ACSL4 may constitute a therapeutic target at the initial stages of chemotherapeutic treatment to prevent the activation of pathways associated with increased tumor aggressiveness.