Interactions between lymphoma cells and stromal cells play a key role in promoting tumor survival and development of drug resistance. We identified differences in key signaling pathways between the JeKo-1 and REC-1 mantle cell lymphoma (MCL) cell lines, displaying different patterns of stromal cell adhesion and chemotaxis towards stroma-conditioned medium. The identified adhesion-regulated genes reciprocated important aspects of microenvironment-mediated gene modulation in MCL patients. Five-hundred and ninety genes were differently regulated between the cell lines upon adhesion to stromal cells, while 32 genes were similarly regulated in both cell lines. Regulation of B-cell Receptor (BCR) signature genes in adherent cells was specific for JeKo-1. Inhibition of BCR using siRNA or clinically approved inhibitors, Ibrutinib and Acalabrutinib, decreased adhesion of JeKo-1, but not REC-1 cells. Cell surface levels of chemokine receptor CXCR4 were higher in JeKo-1, facilitating migration and adhesion of JeKo-1 but not REC-1 cells. Surface levels of ICAM1 adhesion protein differ for REC-1 and JeKo-1. While ICAM1 played a positive role in adherence of both cell lines to stromal cells, S1PR1 had an inhibitory effect. Our results provide a model framework for further investigation of mechanistic differences in patient-response to new pathway-specific drugs.
SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase (dNTPase) that restricts viral replication in infected cells and limits the sensitivity to cytarabine by hydrolysing its active metabolite, as recently shown in acute myeloid leukemia. Cytarabine is an essential component in the Nordic mantle cell lymphoma protocols (MCL2 and MCL3) for induction and high-dose chemotherapy treatment before autologous stem cell transplantation for younger patients with mantle cell lymphoma (MCL). We here investigated the expression of SAMHD1 in a population-based cohort of MCL (N = 150). SAMHD1 was highly variably expressed in MCL (range, 0.4% to 100% of positive tumor cells). Cases with blastoid/pleomorphic morphology had higher SAMHD1 expression (P = 0.028) and SAMHD1 was also correlated to tumor cell proliferation (P = 0.016). SAMHD1 expression showed moderate correlation to the expression of the transcriptional regulator SOX11 (P = 0.036) but genetic silencing of SOX11 and SAMHD1 by siRNA in MCL cell lines did not suggest mutual regulation. We hypothesized that expression of SAMHD1 could predict short time to progression in patients treated with Cytarabine as part of high-dose chemotherapy. Despite the correlation with known biological adverse prognostic factors, neither low or high SAMHD1 expression correlated to PFS or OS in patients treated according to the Nordic MCL2 or MCL3 protocols (N = 158).
Introduction Cannabinoid receptors type 1 (CB1) and type 2 (CB2) are tentative treatment-targets in cancer. They are activated by endogenous cannabinoids and by plant cannabinoids such as tetrahydrocannabinol (THC). CB2 is expressed in normal and malignant lymphocytes while CB1 expression is low in normal lymphocytes but high in mantle cell lymphomas and half of cases of chronic lymphocytic leukemia (CLL). Agonists to CB1 and CB2 induce cell death of CB1 or CB2 expressing lymphoid cell lines (Gustafsson, K. et al. Int J Cancer 2008). CB1 and CB2 regulate tissue localization and homing of leukocytes (Muppidi JR, et al. J Exp Med. 2011; Wasik et al., 2014, Oncoscience). We here report the effects of Sativex, which contains a whole-plant mixture of Cannabis sativa with exact proportions of THC and the partial CB1-antagonist cannabidiol (CBD), on patients with indolent B-cell lymphoma. Methods Patients, 18-80 years, with a leukemic indolent B-cell lymphoma without treatment indication, were given a single administration of Sativex, as an oral mucosal spray. The cannabis compound was given at 9 AM and patients were sampled at 0, 2, 4, 6, 24 and 168 hours. They were also sampled at a prior non-treatment day at the same hours of the day to compensate for any circadian rhythms of blood leukocytes. Blood samples were analyzed using blood chemistry and flow cytometry to quantify lymphoma and non-malignant cells. Apoptosis was measured by caspase-3 activation. CB1 and CB2 mRNA levels were quantified using qPCR in enriched lymphoma cells. Results 23 patients were included (Table 1). Maximum tolerated dose was determined to be 7 actuations, containing 18.9mg THC and 17.5mg CBD. This dose was given to 15 patients. Side effects were mostly grade 1 and manageable (Table 2) and all patients could return home at 3 PM. At every time point on the treatment day, there was a significant decrease in lymphocyte counts compared with 0 hours (2 hours, P = 0.004; 4 hours, P < 0.001; 6 hours, P = 0.007), with nadir usually at 4 hours after drug administration (median nadir 0.85 relative to baseline). On the control day, lymphocytes decreased significantly at 4 hours (P = 0.031) and 6 hours (P = 0.026) (median nadir of 0.93 compared to baseline). Changes in clonal B cells were the same as in lymphocytes. The larger median nadir on treatment day was not due to increased cell-death as measured by activated caspase 3. In the non-clonal B-cells, there was no circadian variation during the control day, but a decrease after treatment was detectable (2 hours: P = 0.01; 4 hours: P = 0.034; 6 hours: P = 0.031). T-cells showed no circadian changes and decreased after treatment (4 hours, P = 0.06; 6 hours, P = 0.009). For NK cells, the pattern, regardless of administration of cannabinoids, was a decrease at 6 hours (6 hours no drug, P = 0.051; 6 hours with drug P = 0.013). A week after administration of the cannabis compound, all non-malignant lymphocytes had returned to baseline levels, but the clonal B cells had significantly increased (P = 0.011). Neutrophils increased significantly after treatment (4 hours, P = 0.007; 6 hours, P = 0.005) whereas platelets decreased at 2 hours (P = 0.003). CB2 mRNA was expressed in all lymphomas and 17/23 lymphomas expressed CB1 mRNA. There was no correlation between baseline levels of CB2, CB1 or plasma concentrations of THC and CBD to nadir of lymphocytes (all P > 0.4). The cannabis compound reduced lymphocyte levels both in CB1-positive and CB1-negative lymphoma (CB1+, P = 0.028; CB1-, P = 0.013). Conclusion This study demonstrates that it is safe to administrate a single dose of Sativex to elderly patients with indolent B-cell lymphoma with regards to adverse events. We show that the cannabis compound quickly reduces lymphoma cell numbers in peripheral blood. There was no evidence of activation of caspase 3; this suggests that the reduction of lymphoma cells in blood might be due to redistribution from blood rather than apoptosis. We have also detected an apparent circadian rhythm of the peripheral numbers of malignant lymphocytes. Our findings suggest that the drug might promote homing of lymphoma cells from blood into secondary lymphoid organs where they receive pro-survival signals. Therefore, this cannabinoid compound should be used with caution in patients with indolent leukemic lymphomas. Further studies are needed to dissect the signaling pathways affected by cannabinoids in B-cell lymphoma. Disclosures Wahlin: Roche and Gilead: Consultancy. OffLabel Disclosure: Sativex is an oromucosal spray containing whole plant Cannabis sativa. In Europe is is registred for use against spasticity caused by multiple sclerosis.
Background: Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma with a high rate of relapses after therapy. Chronic lymphocytic leukemia (CLL) is a heterogeneous disease with varied outcome. For both diseases there is a need for new therapies. Cannabinoid receptors (CBs), which are overexpressed in most cases of MCL and CLL compared to normal B cells (Islam et al., 2003; Gustafsson et al., 2008; Freund et al., 2016) are promising novel therapeutic targets. CBs are membrane-bound receptors that convey signals from the microenvironment to the cells. There are two types of CBs: CB1 and CB2. CB1 is suggested to be involved in retention and/or egress of MCL cells from the tissue to the blood circulation (Wasik et al., 2014). CB2 is expressed by normal B-cells where it regulates positioning and retention of cells in tissue (Pereira et al., 2009; Basu et al., 2011; Muppidi et al., 2011) and in pre-B-cell acute lymphoblastic leukemia, involved in the energy metabolism (Chan et al., 2017). The retention/egress of the B-cell lymphoma cells is mainly regulated by chemokine receptors and adhesion molecules. The chemokine receptor CXCR4 is one of the most highly expressed chemokine receptors in MCL and CLL. 2-arachidonoylglycerol (2-AG, CB1/CB2 endogenous ligand) and CXCL12 (CXCR4 ligand) are synthetized and secreted by stromal cells in the bone marrow (Kose et al., 2018; Burger and Gribben, 2014). The endocannabinoids levels in cancer are suggested to have a role in cancer progression (Sailler et al., 2014) while CXCL12 is already a candidate target for therapy using a CXCR4 inhibitor AMD3100. Aim: To investigate a possible crosstalk between CBs and CXCR4 in MCL and CLL cells. Methods: Patients with newly diagnosed MCL (n=8) or CLL (n=25) gave informed consent to participate in the study. Lymphoma cells were enriched by negative selection. Fifteen primary lymphoma samples and the JeKo MCL cell line were subjected to chemotaxis towards CXCL12 and/or 2-AG. CXCR4 membrane expression was assessed by flow cytometry. Selective CB1 and CB2 antagonists were used to investigate the underlying mechanisms. CB1, CB2 and CXCR4 encoding genes levels were measured by qPCR and normalized to B cells from tonsil. Results and Conclusion: 2-AG induced chemotaxis in 11/15 MCL and CLL samples. In JeKo, 2-AG-induced migration was blocked by a CB2 antagonist, suggesting that signaling via CB2 is involved. When the primary cells were subjected to migration towards CXCL12, two patterns of chemotaxis were observed. The first pattern was seen in 7/15 samples that migrated towards CXCL12. In these samples, the migration was inhibited when 2-AG was combined with CXCL12. The second type of response was observed in 8/15 samples, those samples did not migrate towards CXCL12 but chemotaxis was enhanced by combining 2-AG and CXCL12. MCL and CLL samples expressed variable mRNA levels of CB1 (RFI range: 0.0-204) and CB2 (RFI range: 0.8-14.3) and all expressed CXCR4 at mRNA (RFI range: 0.1-215.8) and protein (MFI range: 1278-19301) levels that did not differ neither between the two diseases nor between the two migratory groups. When all 15 samples were combined, CB1 mRNA levels, but not CB2 mRNA, correlated to the chemotaxis towards CXCL12 (Spearman correlation coefficient = 0.626; p=0.01). In contrast, CB2 mRNA levels, but not CB1, correlated to chemotaxis towards 2-AG (Spearman correlation coefficient = 0.532; p=0.04), which is in agreement with the effects observed in JeKo. Furthermore, CB1 and CB2 mRNA levels correlated to chemotaxis towards the combination of CXCL12 and 2-AG both (for CB1 mRNA: Spearman correlation coefficient= 0.588; p=0.02 and for CB2 mRNA: 0.589; p=0.02). Neither CXCL12-induced CXCR4 receptor internalization, nor recycling was influenced by 2-AG incubation. Our findings indicate a novel pathway regulating chemotaxis of MCL and CLL implicating a cross-talk between CBs and CXCR4. The fact that the capacity to internalize CXCR4 remained intact after incubation with 2-AG suggests that the reduced CXCL12-mediated migration when 2-AG was combined could be due to an impaired downstream signaling in lymphoma cells. Importance: Lymphoma cells residing in the tissue receive pro-survival stimuli and are protected from chemotherapy by signals from the microenvironment. A better understanding of how lymphoma cell migration and tissue retention are regulated can be a step towards more efficient therapies. Disclosures Wahlin: Gilead: Consultancy, Honoraria, Research Funding; Roche: Research Funding.
To survive chemotherapy, lymphoma cells can relocate to protective niches where they receive support from the non-malignant cells. The biolipid 2-arachidonoylglycerol (2-AG), an agonist for the cannabinoid receptors CB1 and CB2, is released by stromal cells in the bone marrow. To investigate the role of 2-AG in lymphoma, we analyzed the chemotactic response of primary B-cell lymphoma cells enriched from peripheral blood of twenty-two chronic lymphocytic leukemia (CLL) and five mantle cell lymphoma (MCL) patients towards 2-AG alone and/or to the chemokine CXCL12. The expression of cannabinoid receptors was quantified using qPCR and the protein levels visualized by immunofluorescence and Western blot. Surface expression of CXCR4, the main cognate receptor to CXCL12, was analyzed by flow cytometry. Phosphorylation of key downstream signaling pathways activated by 2-AG and CXCL12 were measured by Western blot in three MCL cell lines and two primary CLL samples. We report that 2-AG induces chemotaxis in 80% of the primary samples, as well as 2/3 MCL cell lines. 2-AG induced in a dose-dependent manner, the migration of JeKo-1 cell line via CB1 and CB2. 2-AG affected the CXCL12-mediated chemotaxis without impacting the expression or internalization of CXCR4. We further show that 2-AG modulated p38 and p44/42 MAPK activation. Our results suggest that 2-AG has a previously unrecognized role in the mobilization of lymphoma cells by effecting the CXCL12-induced migration and the CXCR4 signaling pathways, however, with different effects in MCL compared to CLL.
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