Downregulation of deoxycytidine kinase in cytarabine-resistant mantle cell lymphoma cells confers cross-resistance to nucleoside analogs gemcitabine, fludarabine and cladribine, but not to other classes of anti-lymphoma agents

Abstract

BackgroundMantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma associated with poor prognosis. Implementation of high-dose cytarabine (araC) into induction therapy became standard-of-care for all newly diagnosed younger MCL patients. However, many patients relapse even after araC-based regimen. Molecular mechanisms responsible for araC resistance in MCL are unknown and optimal treatment strategy for relapsed/refractory MCL patients remains elusive.MethodsFive araC-resistant (R) clones were derived by long-term culture of five MCL cell lines (CTRL) with increasing doses of araC up to 50 microM. Illumina BeadChip and 2-DE proteomic analysis were used to identify gene and protein expression changes associated with araC resistance in MCL. In vitro cytotoxicity assays and experimental therapy of MCL xenografts in immunodeficient mice were used to analyze their relative responsiveness to a set of clinically used anti-MCL drugs. Primary MCL samples were obtained from patients at diagnosis and after failure of araC-based therapies.ResultsMarked downregulation of deoxycytidine-kinase (DCK) mRNA and protein expression was identified as the single most important molecular event associated with araC-resistance in all tested MCL cell lines and in 50% primary MCL samples. All R clones were highly (20-1000x) cross-resistant to all tested nucleoside analogs including gemcitabine, fludarabine and cladribine. In vitro sensitivity of R clones to other classes of clinically used anti-MCL agents including genotoxic drugs (cisplatin, doxorubicin, bendamustine) and targeted agents (bortezomib, temsirolimus, rituximab) remained unaffected, or was even increased (ibrutinib). Experimental therapy of immunodeficient mice confirmed the anticipated loss of anti-tumor activity (as determined by overall survival) of the nucleoside analogs gemcitabine and fludarabine in mice transplanted with R clone compared to mice transplanted with CTRL cells, while the anti-tumor activity of cisplatin, temsirolimus, bortezomib, bendamustine, cyclophosphamide and rituximab remained comparable between the two cohorts.ConclusionsAcquired resistance of MCL cells to araC is associated with downregulation of DCK, enzyme of the nucleotide salvage pathway responsible for the first phosphorylation (=activation) of most nucleoside analogs used in anti-cancer therapy. The data suggest that nucleoside analogs should not be used in the therapy of MCL patients, who relapse after failure of araC-based therapies.

Targeting of BCL2 Family Proteins with ABT-199 and Homoharringtonine Reveals BCL2- and MCL1-Dependent Subgroups of Diffuse Large B-Cell Lymphoma

“…Western blotting (WB) was performed as previously described (17). Antibodies were obtained from Cell Signaling: BAK (3814), BAX (2774), BCL-XL (2764), BID (2002), BIM (2933), PUMA (4976), cleaved PARP (9541), BCL-6 (4242); ENZO LS/Alexis: CASP3 (ALX-804-305), cFLIP (ALX-804-961); Santa Cruz: Actin-HRP (sc-1616), BAD (sc-8044), MCL1 (sc-819, sc-12756), NOXA (sc-56169), Actin (sc-1615), cMYC (sc-40); or BD Pharmingen: BCL2 (610539).…”

Pevonedistat, a NEDD8-activating enzyme inhibitor, is active in mantle cell lymphoma and enhances rituximab activity in vivo

“…Cytarabine-resistant cell lines (Mino-AraCR, HBL-2-AraCR, Jeko-1-AraCR, and Rec-1-AraCR) were generated and characterized as previously described. 21,22 Neoplastic B cells were isolated from pretreatment biopsy tissue obtained from patients with B-cell non-Hodgkin lymphoma or lymphocyte-predominant Hodgkin lymphoma receiving therapy at Roswell Park Cancer Institute (RPCI) as previously described. 23 …”

Antiproliferative and Antimigration Activities of Fluoro-Neplanocin A via Inhibition of Histone H3 Methylation in Triple-Negative Breast Cancer

“…Since the first descriptions of the chemical synthesis of adenosine and guanosine in the 1940s, modified nucleosides have become valuable therapeutic agents in an enormous number of situations because of their relative safety and significant activity levels [25,50]. Nucleoside analogs comprise a main class of small molecule-based antiviral, antitumor, and antibacterial agents [28,51,52]. Previously, we reported the synthesis and biological activity of halo-analogs of NepA, among which we identified F-NepA as a significantly more potent inhibitor of SAH relative to the parent compound, whereas chloro-and bromo-substituted analogs were relatively less active [33].…”