Chemotherapy selection pressure alters sphingolipid composition and mitochondrial bioenergetics in resistant HL-60 cells

Li-Pin Kao,Samy A.F Morad,Traci S Davis,Matthew R Macdougall,Miki Kassai,Noha Abdelmageed,Todd E Fox,Mark Kester,Thomas P Loughran,Jose' L Abad,Gemma Fabrias,Su-Fern Tan,David J Feith,David F Claxton,Sarah Spiegel,Kelsey H Fisher-Wellman,Myles C Cabot

doi:10.1194/jlr.ra119000251

Abstract

The combination of daunorubicin (dnr) and cytarabine (Ara-C) is a cornerstone of treatment for acute myelogenous leukemia (AML); resistance to these drugs is a major cause of treatment failure. Ceramide, a sphingolipid (SL), plays a critical role in cancer cell apoptosis in response to chemotherapy. Here, we investigated the effects of chemotherapy selection pressure with Ara-C and dnr on SL composition and enzyme activity in the AML cell line HL-60. Resistant cells, those selected for growth in Ara-C- and dnr-containing medium (HL-60/Ara-C and HL-60/dnr, respectively), demonstrated upregulated expression and activity of glucosylceramide synthase, acid ceramidase (AC), and sphingosine kinase 1 (SPHK1); were more resistant to ceramide than parental cells; and displayed sensitivity to inhibitors of SL metabolism. Lipidomic analysis revealed a general ceramide deficit and a profound upswing in levels of sphingosine 1-phosphate (S1P) and ceramide 1-phosphate (C1P) in HL-60/dnr cells versus parental and HL-60/Ara-C cells. Both chemotherapy-selected cells also exhibited comprehensive upregulations in mitochondrial biogenesis consistent with heightened reliance on oxidative phosphorylation, a property that was partially reversed by exposure to AC and SPHK1 inhibitors and that supports a role for the phosphorylation system in resistance. In summary, dnr and Ara-C selection pressure induces acute reductions in ceramide levels and large increases in S1P and C1P, concomitant with cell resilience bolstered by enhanced mitochondrial remodeling. Thus, strategic control of ceramide metabolism and further research to define mitochondrial perturbations that accompany the drug-resistant phenotype offer new opportunities for developing therapies that regulate cancer growth.

Highlights

The combination of daunorubicin and cytarabine (Ara-C) is a cornerstone of treatment for acute myelogenous leukemia (AML); resistance to these drugs is a major cause of treatment failure
Lactate dehydrogenase (LDH) activity, which can be elevated in drug resistance [32,33,34,35], was significantly higher in both HL-60/dnr and HL-60/Ara-C cells compared with wt (Fig. 1C)
Acquired resistance of leukemia cells to AraC has been shown to be associated with the upregulation of aldehyde dehydrogenase 1 (ALDH1A2) [36], a characteristic demonstrated in the HL-60/Ara-C model but not in HL-60/dnr or wt cells (Fig. 1E)

Summary

Introduction

The combination of daunorubicin (dnr) and cytarabine (Ara-C) is a cornerstone of treatment for acute myelogenous leukemia (AML); resistance to these drugs is a major cause of treatment failure. Lipidomic analysis revealed a general ceramide deficit and a profound upswing in levels of sphingosine 1-phosphate (S1P) and ceramide 1-phosphate (C1P) in HL-60/dnr cells versus parental and HL-60/Ara-C cells Both chemotherapyselected cells exhibited comprehensive upregulations in mitochondrial biogenesis consistent with heightened reliance on oxidative phosphorylation, a property that was partially reversed by exposure to AC and SPHK1 inhibitors and that supports a role for the phosphorylation system in resistance. Chemotherapy resistance, which can be intrinsic or acquired, is the major cause of treatment failure [1], as most patients subsequently relapse with a chemoresistant disease that is difficult to treat and manage

Methods

Results

Conclusion