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Crosstalk between ROR1 and BCR pathways defines novel treatment strategies in mantle cell lymphoma.

ABSTRACT: Mantle cell lymphoma (MCL) is an aggressive form of non-Hodgkin B-cell lymphoma with poor prognosis due to drug resistance. Introduction of the Bruton tyrosine kinase (BTK) inhibitor ibrutinib has markedly improved MCL therapy outcome, but drug resistance remains a challenge. The selective cell-surface expression of oncogenic receptor tyrosine kinase-like orphan receptor 1 (ROR1) pseudokinase in hematological malignancies has made this receptor a promising candidate for targeted therapy. We sought to identify the molecular mechanism underlying divergent ROR1-mediated apoptotic responses in MCL cell lines and primary samples. We show that targeting ROR1 expression resulted in downregulation of NF-?B p65 levels and that activation of the NF-?B pathway can antagonize ROR1-mediated apoptotic responses. High-throughput drug-sensitivity testing of MCL cells before and after ROR1 targeting revealed synergistic effects between cotargeting of ROR1 and the B-cell antigen receptor (BCR) or Bcl-2 family, underlining the high potential for ROR1-targeted therapies in overcoming MCL drug resistance. However, inhibition of the BCR pathway by targeted drugs such as ibrutinib can impair ROR1 expression and consequently ROR1-targeted treatments, underscoring the importance of inhibiting both pathways to augment cancer cell killing. Considering the central role of NF-?B pathway activation in B-cell malignancies, this study highlights key factors that can modulate ROR1-targeted treatments in hematological cancers.

SUBMITTER: Karvonen H

PROVIDER: S-EPMC5737127 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Crosstalk between ROR1 and BCR pathways defines novel treatment strategies in mantle cell lymphoma.

Karvonen Hanna H Chiron David D Niininen Wilhelmiina W Ek Sara S Jerkeman Mats M Moradi Elaheh E Nykter Matti M Heckman Caroline A CA Kallioniemi Olli O Murumägi Astrid A Ungureanu Daniela D

Blood advances 20171109 24

Mantle cell lymphoma (MCL) is an aggressive form of non-Hodgkin B-cell lymphoma with poor prognosis due to drug resistance. Introduction of the Bruton tyrosine kinase (BTK) inhibitor ibrutinib has markedly improved MCL therapy outcome, but drug resistance remains a challenge. The selective cell-surface expression of oncogenic receptor tyrosine kinase-like orphan receptor 1 (ROR1) pseudokinase in hematological malignancies has made this receptor a promising candidate for targeted therapy. We soug ...[more]

PMID: 29296874

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Project description:We used shotgun proteomics to identify plasma membrane and lipid raft proteins purified from B cells obtained from mantle cell lymphoma (MCL) patients in leukemic phase. Bioinformatics identified 111 transmembrane proteins, some of which were profiled in primary MCL cases, MCL-derived cell lines, and normal B cells using RT-PCR and Western blotting. Several transmembrane proteins, including CD27, CD70, and CD31 (PECAM-1), were overexpressed when compared with normal B cells. CD70 was up-regulated (>10-fold) in three of five MCL patients along with its cognate receptor CD27, which was up-regulated (4-9-fold) in five of five patients, suggesting that MCL cells may undergo autocrine stimulation via this signaling pathway. Activated calpain I and protein kinase C betaII were also detected in the plasma membranes, suggesting that these proteins are constitutively active in MCL. Protein kinase C betaII has been associated with lipid rafts, and shotgun proteomics/protein profiling revealed that key lipid raft proteins, raftlin (four of five patients) and CSK (C-terminal Src kinase)-binding protein (Cbp)/phosphoprotein associated with glycosphingolipid-enriched microdomains (PAG) (four of four patients) were down-regulated in MCL. Levels of other known lipid raft proteins, such as Lyn kinase and flotillin 1, were similar to normal B cells. However, 5-lipoxygenase (5-LO), a key enzyme in leukotriene biosynthesis, was associated with lipid rafts and was up-regulated approximately 7-fold in MCL compared with normal B cells. Significantly inhibitors of 5-LO activity (AA861) and 5-LO-activating protein (FLAP) (MK886, its activating enzyme) induced apoptosis in MCL cell lines and primary chronic lymphocytic leukemia cells, indicating an important role for the leukotriene biosynthetic pathway in MCL and other B cell malignancies. Thus, using shotgun proteomics and mRNA and protein expression profiling we identified a subset of known and unknown transmembrane proteins with aberrant expression in MCL plasma membranes. These proteins may play a role in the pathology of the disease and are potential therapeutic targets in MCL.

Project description:Mantle cell lymphoma (MCL) is a B-cell non-Hodgkin lymphoma with typically aggressive behavior. The genetic signature is the chromosomal translocation t(11;14)(q13;q32) resulting in overexpression of cyclin D1. Asymptomatic newly diagnosed MCL patients with low tumor burden can be closely observed, deferring therapy to the time of disease progression. Although MCL classically responds to upfront chemotherapy, it remains incurable with standard approaches. For patients in need of frontline therapy, the initial decision is whether to proceed with an intensive treatment strategy or a non-intensive treatment strategy. In general, given the unfavorable risk-benefit profile, older MCL patients should be spared intensive strategies, while younger and fit patients can be considered for intensive strategies. The bendamustine and rituximab (BR) regimen is becoming an increasingly popular treatment option among the elderly population, with improved progression-free survival (PFS) and acceptable side-effect profile. Although rituximab maintenance after R-CHOP improves survival outcomes in elderly patients, no clinical trial to date has shown statistical significance to support the use of rituximab maintenance after BR induction in older patients. In young and fit patients with MCL, an intensive strategy to maximize the length of first remission has emerged as a worldwide standard of care. With current high-dose cytarabine-containing immunochemotherapy regimens followed by autologous stem cell transplantation, the median PFS has exceeded 7 years. In the relapsed or refractory (R/R) setting, reduced intensity conditioning allogeneic hematopoietic stem cell transplantation may offer the highest likelihood of long-term survival in young R/R MCL patients, at the cost of increased risk of non-relapse mortality and chronic graft versus host disease. Novel agents targeting activated pathways in MCL cells, such as bortezomib, lenalidamide, ibrutinib and temsirolimus are now available for the management of R/R disease.

Dataset Information

Crosstalk between ROR1 and BCR pathways defines novel treatment strategies in mantle cell lymphoma.

Publications

Crosstalk between ROR1 and BCR pathways defines novel treatment strategies in mantle cell lymphoma.

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