Lenalidomide Inhibits Proliferation Of Chronic Lymphocytic Leukemia Cells Via a Cereblon/p21WAF1/Cip1-Dependent Mechanism

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4139-4139
Author(s):  
Jessie-Farah Fecteau ◽  
Laura G Corral ◽  
Diahnn Futalan ◽  
Svetlana Gaidarova ◽  
Ila Bharati ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Chronic Lymphocytic Leukemia ◽  
Research Funding ◽  
Lymphocytic Leukemia ◽  
Dependent Manner ◽  
Direct Effects ◽  
P53 Expression ◽  
The Impact

Abstract Lenalidomide has demonstrated clinical activity in patients with chronic lymphocytic leukemia (CLL). However, its mechanism of action is not fully elucidated. Lenalidomide is not directly cytotoxic to CLL cells in vitro, but can alter the capacity of CLL cells to interact with cells in its microenvironment. This has led to the speculation that its primary activity is indirect, although direct effects on CLL cells have been observed. In this study, we examined the direct effects of lenalidomide on CLL cells. We performed transcriptome analysis on primary CLL cell samples exposed to lenalidomide in vitro for 6 and 24hrs and found a significant upregulation of the cyclin-dependent kinase inhibitor p21WAF1/Cip1 (p21), which was also confirmed at the protein level. Since p21 can inhibit the progression of cells from G1 to S phase of the cell cycle, this suggests that lenalidomide may render CLL cells less responsive to proliferation stimuli from the microenvironment. To test this hypothesis, we induced CLL cells to proliferate in vitro using accessory cells made to express CD154 and media containing human interleukin (IL)-4 and IL-10. We monitored for proliferation of CLL cells cultured with and without lenalidomide using carboxyfluorescein succinimidyl ester (CFSE). In repeated experiments, we observed that lenalidomide consistently and significantly inhibited the proliferation of CLL cells in a dose-dependent manner, at concentrations that are achieved in treated patients. Evaluation of the DNA content of CLL cells using propidium iodide and flow cytometry also revealed that lenalidomide significantly decreased the fraction of CLL cells in S and in G2/M phases of the cell cycle and concomitantly increased the percentage of CLL cells in G0/G1 phases. This block in cell proliferation also was accompanied by the upregulation of p21, and the extent of which correlated with the degree to which leukemia-cell proliferation was inhibited. In additional studies, we used small interfering RNA (siRNA) to silence p21 in CLL cells and measured the effect of silencing on cell proliferation in the presence of lenalidomide. We observed that the ability of lenalidomide to inhibit CLL cell proliferation was significantly reduced in CLL cells silenced for p21 compared to CLL cells transfected with control siRNA, supporting a role for p21 expression in mediating the proliferation block induced by lenalidomide. We did not however observe the induction of p53 expression following lenalidomide exposure, suggesting that lenalidomide may upregulate p21 via a p53-independent mechanism. Cereblon (CRBN) is the only known molecular target of lenalidomide. To functionally interrogate the potential role of CRBN in lenalidomide activity on CLL cells, we used siRNA to silence CRBN in primary CLL cells and monitored the impact of silencing on the ability of lenalidomide to upregulate p21 and to inhibit proliferation. We observed lower levels of p21 expression in CRBN-silenced cells exposed to lenalidomide compared to cells transfected with non-specific siRNA, suggesting that CRBN may play a role in p21 upregulation. Furthermore, we observed that CRBN silencing significantly abrogated the anti-proliferative effect of lenalidomide. These results indicate the involvement of CRBN in the anti-proliferative activity of lenalidomide, which is mediated, at least in part, by p21. This study demonstrates that lenalidomide inhibits the proliferation of CLL cells in a CRBN/p21-dependent manner. This direct effect of lenalidomide on CLL cells may account in part for the highly infrequent observation of disease progression in patients receiving long-term maintenance therapy with this agent (Blood, 2013, PMID:23801633). Disclosures: Fecteau: Celgene: Research Funding. Corral:Celgene: Employment. Gaidarova:Celgene: Employment. Cathers:Celgene: Employment. Lopez-Girona:Celgene: Employment. Messmer:Celgene: Research Funding. Kipps:Celgene: Membership on an entity’s Board of Directors or advisory committees, Research Funding.

Chronic Lymphocytic Leukemia Cells With Trisomy 12 Home To The Bone Marrow In a CXCR4-Independent Manner and Are Prone To Proliferate In Vitro

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 870-870
Author(s):  
Evelyn Hutterer ◽  
Elisabeth Hinterseer ◽  
Sylvia Ganghammer ◽  
Gabriele Brachtl ◽  
Daniela Asslaber ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Chronic Lymphocytic Leukemia ◽  
Research Funding ◽  
Lymphocytic Leukemia ◽  
Dependent Manner ◽  
Independent Manner ◽  
Atypical Cell ◽  
Trisomy 12 ◽  
Inside Out

Abstract Trisomy 12 (tri12) is a frequent chromosomal aberration in chronic lymphocytic leukemia (CLL) associated with atypical cell morphology, high in vivo tumor proliferation activity and a predisposition to Richter’s transformation. Tri12 harboring CLL cells express increased levels of the negative prognostic marker CD49d, the α4 subunit of the integrin very late antigen 4 (VLA-4), which we previously identified as a key regulator of CLL cell homing to bone marrow (BM). During this process, inside-out activation of VLA-4 upon CXCR4 binding to endothelially displayed CXCL12 is thought to upregulate the adhesive properties of VLA-4 and augment the arrest of CLL cells on the VCAM-1 presenting vessels. Here, we investigated the functional interplay of VLA-4 and CXCR4 in CLL carrying tri12. We first found that the upregulation of CD49d expression in this subset (MFIR CD49d 9.8±5.3 (n=22) vs. 2.7±3.9 (n=126), p<0.0001) was paralleled by their reduced CXCR4 expression (MFIR CXCR4 11.8±7.2 (n=22) vs. 22.7±14.2 (n=126), p=0.0003). Using short term adoptive transfers, we compared the ability of tri12 and no tri12 CLL cells to home to the BM of NOD/SCID mice. 5-10x106 CLL cells were injected into tail vein and homing was evaluated after 3 hours. Based on their more frequent CD49d high phenotype, we observed increased homing rates (homed human CLL cells per 106 injected cells per 106 acquired murine cells) of tri12 compared to no tri12 CLL (225±160 (n=7) vs. 90±117 (n=20), p=0.025). However, when comparing CD49d+ tri12 and CD49d+ no tri12 subsets, we did not observe any significant differences in their homing capacity. To further study CXCL12/CXCR4 function in BM homing, we pretreated mice with either the novel CXCL12 antagonist NOX-A12 or the CXCR4 inhibitor AMD3100 prior to CLL cell injection. While homing of no tri12 CLL cells (n=3, in duplicates) was reduced by both pretreatments (homing rates 137 vs 38 vs 30), the homing capacity of tri12 CLL cells (n=3, in duplicates) was not affected. We next tested whether VLA-4 expressed on these cells was able to undergo CXCL12-induced activation and support cell arrest under shear conditions. To this end, we perfused CLL cells over VCAM-1 or VCAM-1/CXCL12 substrates and analyzed rates and categories of cell tethering at a single cell level by videomicroscopy. CXCL12 induced the arrests of no tri12 CLL cells (n=3) on VCAM-1 under shear flow in a CXCR4 and VLA-4 dependent manner. In contrast, tri12 CLL cells (n=3) robustly tethered to VCAM-1 in the absence of the chemokine, and interactions could not be further enhanced by additional CXCL12 nor could they be abrogated by use of AMD3100. This failure of CXCR4-induced adhesion was not based on a general defect in CXCR4 functionality as in vitro chemotaxis of tri12 CLL cells (n=5) towards CXCL12 was fully maintained. To detect potential differences in VLA-4 affinity regulation, we used a conformationally sensitive antibody that recognizes epitopes induced by VLA-4 ligation, and an LDV-containing VLA-4 specific ligand to probe resting integrin affinity. Also, we used a small fluorescent ligand to study rapid VLA-4 affinity changes during inside-out chemokine induced activation. On resting tri12 CLL, VLA-4 exhibited an affinity state similar to that observed on circulating lymphocytes, and tri12 CLL cells failed to undergo the rapid affinity up-regulation triggered by CXCL12 pretreatment, in keeping with tethering experiments. Next, we investigated whether the tumor microenvironment has a different influence on the behavior of the tri12 subset. Therefore we subjected the cells to in vitro co-cultures mimicking the lymphoid proliferation centers. Basal levels of the early activation marker CD69 were similar in tri12 CLL compared to no tri12 cases. Tri12 CLL, however, underwent stronger activation when cultured in presence of accessory cells (%CD69+ cells 60.0±18.5 (n=4) vs. 17.7±20.1 (n=19), p=0.008). Moreover, in several setups, proliferation rates of these cells were increased, irrespective of the proliferative stimulus and detection method used. In summary, our results provide a mechanistical basis at least in part explaining the peculiar and clinical features of the tri12 CLL subset. In light of the specific migratory and proliferative properties of tri12 cells and novel agents targeting particularly these functions, our findings may also imply therapeutical consequences. Disclosures: Greil: NOXXON Pharma AG: Research Funding. Hartmann:NOXXON Pharma AG: Research Funding.

scholarly journals Bone Marrow Hematopoietic Dysfunction in Untreated Chronic Lymphocytic Leukemia Is Partially Mediated By Exposure to Constituents of the Leukemic Microenvironment

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3132-3132
Author(s):  
Bryce Manso ◽  
Kimberly Gwin ◽  
Charla R Secreto ◽  
Henan Zhang ◽  
Wei Ding ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Board Of Directors ◽  
Research Funding ◽  
Lymphocytic Leukemia ◽  
Healthy Controls ◽  
Advisory Committees ◽  
The Impact

Abstract Peripheral immune dysfunction in B-Chronic Lymphocytic Leukemia (CLL) is well-studied and likely relates to the incidence of serious recurrent infections and second malignancies that plague CLL patients. However, the current paradigms of known immune abnormalities are not able to consistently explain these complications and it is not easy to correct CLL patient immune status. Here, we expand on our preliminary reports that demonstrate bone marrow (BM) hematopoietic dysfunction in early and late stage untreated CLL patients. We found reduced short-term functional capacity of hematopoietic progenitors in BM using colony forming unit assays (Figure 1A-C) and flow cytometry revealed significant reductions in frequencies of hematopoietic stem and progenitor cell (HSPC) populations (exemplified by Lin-CD34+ HSPCs, Figure 1D). We further report that protein levels of the transcriptional regulators HIF-1α, GATA-1, PU.1, and GATA-2 are overexpressed in distinct HSPC subsets from CLL patient BM, providing molecular insight into the basis of HSPC dysfunction. Interestingly, sustained myelopoiesis, evaluated by limiting dilution analysis in long-term culture-initiating cell (LTC-IC) assays maintained for five weeks, revealed no difference between healthy controls and CLL patients. These new data indicate that when HSPCs are removed from the leukemic microenvironment for ample in vitro culture time, they recover the ability to sustain myelopoiesis. To further assess the impact of the CLL microenvironment on HSPC biology, isolated HSPCs (CD34+ BM cells) from healthy controls were exposed in vitro to known leukemic microenvironment constituents. Exposure to TNFα, a cytokine constitutively produced by CLL B cells, resulted in rapid increases in PU.1 and GATA-2 proteins (Figure 2A-D). Similarly, addition of TNFα to the LTC-IC assay resulted in a striking ablation of myelopoiesis, even at the highest input cell concentration. Further, overexpression of PU.1 and GATA-2 were observed in HSPCs following co-culture with CLL B cells, a result that was not recapitulated when cells were exposed to IL-10, another cytokine constitutively produced by CLL B cells. These findings indicate specific components of the leukemic microenvironment are involved in HSPC modulation. Together, these findings expand on our previous observations of BM hematopoietic dysfunction in untreated CLL patients and offer new molecular insights into the contribution of the leukemic microenvironment on immunodeficiency in CLL. Disclosures Ding: Merck: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding; MorphoSys: Research Funding; Janssen: Research Funding; Abbvie: Honoraria, Research Funding; Gilead: Honoraria; AstraZeneca: Honoraria, Research Funding. Kay:Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Acerta: Research Funding; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Cytomx Therapeutics: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding.

scholarly journals Effects of Inhibin A on Apoptosis and Proliferation of Bovine Granulosa Cells

Animals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 367 ◽  
Author(s):  
Huitao Xu ◽  
Adnan Khan ◽  
Shanjiang Zhao ◽  
Huan Wang ◽  
Huiying Zou ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Granulosa Cells ◽  
Caspase 3 ◽  
Nuclear Antigen ◽  
Molecular Response ◽  
Dependent Manner ◽  
Inhibin A ◽  
The Impact

Inhibin A is well known for its inhibitory properties against follicle-stimulating hormone (FSH), released through a pituitary–gonadal negative feedback loop to regulate follicular development. Ovarian folliculogenesis, hormonal biosynthesis, and gametogenesis are dependent on inhibins, playing vital roles in promoting or inhibiting cell proliferation. The present study explored the physiological and molecular response of bovine granulosa cells (GCs) to different concentrations of inhibin A in vitro. We treated the primary GCs isolated from ovarian follicles (3–6 mm) with different levels of inhibin A (20, 50, and 100 ng/mL) along with the control (0 ng/mL) for 24 h. To evaluate the impact of inhibin A on GCs, several in vitro cellular parameters, including cell apoptosis, viability, cell cycle, and mitochondrial membrane potential (MMP) were detected. Besides, the transcriptional regulation of pro-apoptotic (BAX, Caspase-3) and cell proliferation (PCNA, CyclinB1) genes were also quantified. The results indicated a significant (p < 0.05) increase in the cell viability in a dose-dependent manner of inhibin A. Likewise, MMP was significantly (p < 0.05) enhanced when GCs were treated with high doses (50, 100 ng/mL) of inhibin A. Furthermore, inhibin A dose (100 ng/mL) markedly improved the progression of the G1 phase of the cell cycle and increased the cell number in the S phase, which was supported by the up-regulation of the proliferating cell nuclear antigen PCNA (20, 50, and 100ng/mL) and CyclinB (100 ng/mL) genes. In addition, higher doses of inhibin A (50 and 100 ng/mL) significantly (p < 0.05) decreased the apoptotic rate in GCs, which was manifested by down regulating BAX and Caspase-3 genes. Conclusively, our study presented a worthy strategy for the first time to characterize the cellular adaptation of bovine GCs under different concentrations of inhibin A. Our results conclude that inhibin A is a broad regulatory marker in GCs by regulating apoptosis and cellular progression.

scholarly journals The Olive Leaves Extract Has Anti-Tumor Effects against Neuroblastoma through Inhibition of Cell Proliferation and Induction of Apoptosis

Nutrients ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 2178
Author(s):  
Fabio Morandi ◽  
Veronica Bensa ◽  
Enzo Calarco ◽  
Fabio Pastorino ◽  
Patrizia Perri ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Viability ◽  
Cell Cycle Progression ◽  
Treatment Strategies ◽  
Annexin V ◽  
Dependent Manner ◽  
Induction Of Apoptosis ◽  
Dose Dependent

Neuroblastoma (NB) is the most common extra-cranial solid tumor of pediatric age. The prognosis for high-risk NB patients remains poor, and new treatment strategies are desirable. The olive leaf extract (OLE) is constituted by phenolic compounds, whose health beneficial effects were reported. Here, the anti-tumor effects of OLE were investigated in vitro on a panel of NB cell lines in terms of (i) reduction of cell viability; (ii) inhibition of cell proliferation through cell cycle arrest; (iii) induction of apoptosis; and (iv) inhibition of cell migration. Furthermore, cytotoxicity experiments, by combining OLE with the chemotherapeutic topotecan, were also performed. OLE reduced the cell viability of NB cells in a time- and dose-dependent manner in 2D and 3D models. NB cells exposed to OLE underwent inhibition of cell proliferation, which was characterized by an arrest of the cell cycle progression in G0/G1 phase and by the accumulation of cells in the sub-G0 phase, which is peculiar of apoptotic death. This was confirmed by a dose-dependent increase of Annexin V+ cells (peculiar of apoptosis) and upregulation of caspases 3 and 7 protein levels. Moreover, OLE inhibited the migration of NB cells. Finally, the anti-tumor efficacy of the chemotherapeutic topotecan, in terms of cell viability reduction, was greatly enhanced by its combination with OLE. In conclusion, OLE has anti-tumor activity against NB by inhibiting cell proliferation and migration and by inducing apoptosis.

scholarly journals Inhibition of the aurora kinases suppresses in vitro NT2-D1 cell growth and tumorigenicity

2009 ◽  
Vol 204 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Salvatore Ulisse ◽  
Yannick Arlot-Bonnemains ◽  
Enke Baldini ◽  
Stefania Morrone ◽  
Silvia Carocci ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Transformation ◽  
Germ Cell Tumors ◽  
Aurora Kinase ◽  
Malignant Cell ◽  
Dependent Manner ◽  
Testicular Germ Cell ◽  
Aurora Kinases

The aurora kinase family members, Aurora-A, -B, and -C (listed as AURKA, AURKB and AURKC respectively in the HUGO Database), are serine/threonine kinases involved in the regulation of chromosome segregation and cytokinesis, and alterations in their expression are associated with malignant cell transformation and genomic instability. Deregulation of the expression of the aurora kinases has been shown to occur also in testicular germ cell tumors (TGCTs) identifying them as putative anticancer therapeutic targets. We here evaluated the in vitro effects of MK-0457, an aurora kinases inhibitor, on cell proliferation, cell cycle, ploidy, apoptosis, and tumorigenicity on the TGCT-derived cell line NT2-D1. Treatment with MK-0457 inhibited cell proliferation in a time- and dose-dependent manner, with IC50=17.2±3.3 nM. MK-0457 did not affect the expression of the three aurora kinases, but prevented their ability to phosphorylate substrates relevant to the mitotic progression. Time-lapse experiments demonstrated that MK-0457-treated cells entered mitosis but were unable to complete it, presenting after short time the typical features of apoptotic cells. Cytofluorimetric analysis confirmed that the treatment with MK-0457 for 6 h induced NT2-D1 cells accumulation in the G2/M phase of the cell cycle and the subsequent appearance of sub-G0 nuclei. The latter result was further supported by the detection of caspase-3 activation following 24-h treatment with the inhibitor. Finally, MK-0457 prevented the capability of the NT2-D1 cells to form colonies in soft agar. In conclusion, the above findings demonstrate that inhibition of aurora kinase activity is effective in reducing in vitro growth and tumorigenicity of NT2-D1 cells, and indicate its potential therapeutic value for TGCT treatment.

scholarly journals Involvement of CED-3/ICE Proteases in the Apoptosis of B-Chronic Lymphocytic Leukemia Cells

Blood ◽  
1997 ◽  
Vol 89 (9) ◽  
pp. 3378-3384 ◽  
Author(s):  
Beatriz Bellosillo ◽  
Mireia Dalmau ◽  
Dolors Colomer ◽  
Joan Gil
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Lymphocytic Leukemia ◽  
Interleukin 4 ◽  
Leukemia Cells ◽  
Parp Cleavage ◽  
Dependent Manner ◽  
Kinase C ◽  
Dose Dependent ◽  
Pkc Activation

Abstract B-chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of long-lived B lymphocytes that express high levels of Bcl-2. We examined the involvement of CED-3/ICE-like proteases in the apoptosis of B-CLL cells. One of the substrates of these proteases is poly(ADP [adenosine 5′-diphosphate]-ribose) polymerase (PARP). The effect of different factors that induce the apoptosis of B-CLL cells on the proteolytic cleavage of PARP has been studied. Treatment of B-CLL cells with different concentrations of dexamethasone (1 to 1,000 μmol/L) induced in a dose-dependent manner the cleavage of PARP. Dexamethasone induced PARP cleavage after 12 hours of incubation, which was almost complete at 48 hours. PARP cleavage during apoptosis of B-CLL cells was studied in cells from eight patients and a correlation was found between cell viability and the degree of PARP cleavage. Incubation in vitro of B-CLL cells with fludarabine for 48 hours induced PARP cleavage in all the cases studied. Protein kinase C (PKC) activation with 100 nmol/L TPA (12-O-tetradecanoylphorbol 13-acetate) or incubation with interleukin-4 (10 ng/mL) prevented either dexamethasone- or fludarabine-induced proteolysis of PARP. Incubation of B-CLL cells with the CED-3/ICE–like protease inhibitor Z-VAD.fmk inhibited spontaneous and dexamethasone-induced PARP cleavage and DNA fragmentation in a dose-dependent manner. Furthermore, Z-VAD.fmk prevented the cytotoxic effect of dexamethasone. These results indicate that CED-3/ICE–like proteases play an important role in the apoptosis of B-CLL cells.

ZAP-70 Expression Is Associated with Increased Migration to SDF-1 in Chronic Lymphocytic Leukemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 587-587
Author(s):  
Yuji Miura ◽  
Elinor Lee ◽  
Federica Gibellini ◽  
Therese White ◽  
Gerald Marti ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Cxcr4 Expression ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Short Exposure ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Western Blots ◽  
Stroma Cell

Abstract Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of mature B lymphocytes in the peripheral blood (PB), lymph nodes (LN) and bone marrow (BM). Increasing evidence suggests that CLL cells depend on survival and proliferation signals provided by stroma cells in LN and BM. The chemokine receptor CXCR4 (CD184) and its ligand stromal cell-derived factor-1 (SDF-1) play an important role in trafficking of lymphocytes and may guide CLL cells to stroma cell niches. ZAP70 expression has prognostic value in CLL but the functional consequences of ZAP70 expression remain incompletely defined. Given that ZAP70 has been implicated in CXCR4 signaling its expression could enhance migration to SDF-1 and thereby promote interactions with stroma cells. As measured by flow cytometry, CXCR4 expression on leukemic cells obtained from different anatomic sites differed; cells from the PB (n=24, median 71% above isotype control) expressed CXCR4 more strongly than cells from BM (n=21, median 39%) and from LN (n=9, median 24%). Expression of CD69, an activation marker, followed a reverse pattern with cells from LN and BM typically showing higher expression than cells from PB, albeit with not detectable difference in expression in several patients. In vitro CLL cells from PB migrated in a dose dependent manner to SDF-1, and cells that had migrated down-modulated CXCR4 expression (89% before migration - 54% after migration). After exposure to SDF-1 CXCR4 expression decreased rapidly and remained virtually absent for at least 24 hours. Several mechanisms apparently decrease CXCR4 expression after contact with SDF-1, including internalization (given rapid re-expression of CXCR4 when SDF-1 is washed off after short exposure), protein degradation or inhibition of translation (evidenced by a decrease in total CXCR4 protein on Western blots), and mRNA degradation or transcriptional inhibition (decrease in mRNA levels more than 6 hours from SDF-1 exposure). In vitro migration of ZAP70(+) CLL cells toward SDF-1 through a 5μm membrane (Migration Index [MI] of 12.0, n=5) was significantly increased compared to ZAP70(−) CLL cells (MI of 2.9, n=4, p<0.05). To exclude effects of contaminating cells we repeated these assays with purified CLL cells (negative selection) with similar results. To model the complex interactions of CLL cells with stroma, we cultured PB derived leukemic cells with or without murine marrow stroma cells (S17). CXCR4 expression on CD19+ cells decreased from 90% without S17 to 50% when cultured on S17 cells, consistent with the known SDF-1 secretion by the murine stroma cell line. Conversely, CD69 expression increased from 58% without S17 to 71% with S17 cells. In addition, culturing of CLL cells on an S17 stroma cell layer extended their survival by several weeks when compared to cultures without S17 cells. Our data is consistent with a model in which CLL cells migrate along an SDF-1 gradient to stroma cell niches in BM and LN where they are activated. ZAP70 expression is associated with more effective migration in an SDF-1 gradient and thereby may facilitate access to growth and survival signals which then could contribute to the more progressive nature of ZAP70(+) CLL. The interaction between leukemic cells and stroma may represent a novel target for therapy of patients with CLL.

Mode of Action of the SDF-1/CXCL12 Inhibiting Spiegelmer® Nox-A12 and Its Impact On Chronic Lymphocytic Leukemia (CLL) Cell Motility and Chemosensitization

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 318-318
Author(s):  
Dirk Zboralski ◽  
Julia Hoellenriegel ◽  
Christian Maasch ◽  
Anna Kruschinski ◽  
Jan A. Burger
Keyword(s):  
Bone Marrow ◽  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Mode Of Action ◽  
Leukemia Cell ◽  
Lymphocytic Leukemia ◽  
Lymphoid Tissues ◽  
Cell Trafficking ◽  
Dependent Manner

Abstract Abstract 318 NOX-A12 is a novel Spiegelmer®-based antagonist of SDF-1/CXCL12, a chemokine involved in the regulation of chronic lymphocytic leukemia (CLL) cell trafficking. Spiegelmers® are mirror-image oligonucleotides that are identified to specifically bind to proteins in a manner conceptually similar to antibodies. Unlike aptamers, however, Spiegelmers® are built from the non-natural L-isomer form of nucleotides which confers resistance to the action of nucleases and avoids potential immunogenicity. CXCL12 is constitutively secreted and presented by bone marrow stromal cells (BMSC) via glycosaminoglycans (GAG) and acts as a homing factor for normal and malignant hematopoietic cells to the bone marrow (BM) and secondary lymphoid tissues via CXCR4 receptors that are expressed at high levels on circulating CLL cells. The microenvironment in the BM and secondary lymphoid tissues, in particular the CXCL12-CXCR4 axis, favors survival and chemotherapy-resistance of leukemic cells. We therefore investigated the effects of NOX-A12 in an in vitro co-culture system to model the interaction of CLL cells with their microenvironment. Surprisingly we observed that NOX-A12 increased pseudoemperipolesis in vitro, i.e. spontaneous leukemia cell migration beneath BMSC. Interestingly, this NOX-A12 induced trans-migration of CLL cells was completely inhibited by the CXCR4 antagonist AMD3100, suggesting a CXCL12/CXCR4 dependent mechanism. We postulated that this observation might result from a direct effect of NOX-A12 on CXCL12 release by the stromal cells. Therefore, we investigated this hypothesis in different BMSC lines (MS-5, R15C, and TSt-4) and we found that NOX-A12 induced a significant CXCL12 release in all three tested cell lines. We asked whether this NOX-A12 dependent increase of CXCL12 of BMSCs is due to release from either intracellular or extracellular storages. Intracellular staining of CXCL12 using flow cytometry did not reveal significant changes when BMSCs were incubated with NOX-A12. Furthermore, the transcription of CXCL12 was not found to be altered after NOX-A12 incubation over a period of three days as shown by quantitative RT-PCR. Rather, CXCL12 is released from extracellular storages of BMSCs. First hints were obtained through a rapid CXCL12 release within five minutes of incubation with NOX-A12. To confirm that CXCL12 is bound to the extracellular surface (by GAGs like heparin) and is being detached by NOX-A12 we first incubated BMSCs with NOX-A12, followed by a wash step and the addition of recombinant CXCL12. Recombinant CXCL12 was bound by BMSCs that were pre-incubated with NOX-A12 but not with a non-functional control (revNOX-A12), indicating that NOX-A12 strips off CXCL12. To corroborate the findings we incubated the BMSCs with heparin which also led to the release of CXCL12 in a dose dependent manner. Of note, the EC50 of heparin regarding CXCL12 release was much higher compared to the EC50 of NOX-A12 (≈ 12 μM vs. 5 nM) revealing the high affinity of NOX-A12 to CXCL12. The competition of NOX-A12 with heparin regarding CXCL12 binding was confirmed by Biacore experiments. Based on these findings, we developed a novel adapted co-culture approach to examine the ability of NOX-A12 to chemosensitize CLL cells. In this setting, we first strip off CXCL12 from BMSCs by NOX-A12 and subsequently add CLL cells which will be either non-treated or treated with chemotherapy (fludarabine combined with bendamustine). We found that NOX-A12 slightly decreased CLL cell viability. As expected, a strong viability decrease was observed with chemotherapy, which could be even further decreased by the combination with NOX-A12, suggesting synergistic effects. In conclusion, we propose that NOX-A12's mode of action is the release of extracellular bound CXCL12 and its subsequent inhibition. Since CXCL12 induces leukemia cell trafficking and homing to tissue microenvironment and also favors leukemia cell survival, we believe that targeting CXCL12 is an attractive approach to remove the protective effects of CXCL12-secreting BMSCs in order to sensitize CLL cells for subsequent chemotherapy. Thus, NOX-A12 represents a very promising agent to significantly improve the treatment of CLL. The compound is currently being tested in a Phase IIa study in relapsed CLL patients. Disclosures: Zboralski: NOXXON Pharma AG, Berlin, Germany: Employment. Maasch:NOXXON Pharma AG: Employment. Kruschinski:NOXXON Pharma AG: Employment. Burger:NOXXON Pharma AG: Consultancy, Research Funding.

scholarly journals Chronic Lymphocytic Leukemia Cells with Mutated Nfkbie Are Positively Selected By Microenvironmental Signals and Display Reduced Sensitivity to Ibrutinib Treatment

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 248-248
Author(s):  
Alice Bonato ◽  
Riccardo Bomben ◽  
Supriya Chakraborty ◽  
Giulia Felician ◽  
Claudio Martines ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Cell Lines ◽  
Research Funding ◽  
Lymphocytic Leukemia ◽  
Pi3k Inhibitor ◽  
Leukemia Cells ◽  
Wild Type ◽  
Clonal Composition

Abstract Inactivating mutations in NF-kB pathway genes, such as the NF-kB inhibitor NFKBIE, are among the more frequent genetic lesions in chronic lymphocytic leukemia (CLL). However, the role of these genetic lesions in CLL pathogenesis and treatment resistance is still largely unknown and requires further study in in vivo models of the disease. To this end, we generated transplantable murine leukemias with inactivating NFKBIE mutations and investigated their impact on leukemia growth and response to ibrutinib (IBR) treatment. The NFKBIE mutations were introduced by CRISPR/Cas9 editing in two recently established autoreactive leukemia lines derived from the Eμ-TCL1 murine CLL model. These cell lines proliferate spontaneously in vitro in a BCR-dependent manner, but also respond with increased proliferation to certain microenvironmental signals, such as those generated by Toll-like receptor (TLR) stimulation (Chakraborty S et al, Blood 2021). To investigate whether NFKBIE mutations can affect the proliferation of these cell lines in vitro, we performed competition experiments with mixed cultures of cells with wild type and mutated NFKBIE. Analysis of the clonal composition after 2 weeks showed no change in the mutant allele frequency (MAF), suggesting that NFKBIE mutations do not affect the spontaneous in vitro growth of the immortalized leukemia cells. However, repeated TLR or BCR stimulation of these cells with CpG-DNA, LPS, anti-IgM or autoantigen resulted in a 2-3 fold increase in MAF, suggesting that NFKBIE mutations provide a growth advantage when the cells are exposed to certain microenvironmental signals (n=3 experiments/condition, P&lt;0.05 for each condition). To investigate the impact of NFKBIE mutations on leukemia growth in vivo, the same cells were transplanted by intraperitoneal injection in wild type mouse recipients (n=8) and the clonal composition was determined 3 weeks later by MAF analysis of cells isolated from peritoneal cavity (PC), blood and spleen. A significant increase in MAF was observed only in leukemia cells isolated from the spleen (P&lt;0.05), suggesting that microenvironmental signals that positively select NFKBIE-mutated cells are available only in certain tissue compartments. Because mutations in other NF-kB pathway genes have been associated with resistance to IBR in mantle cell lymphoma, we next investigated whether NFKBIE mutations can also affect the response to IBR treatment. In vitro BrdU-incorporation experiments showed that IBR inhibits the proliferation of cells with mutated NFKBIE to a significantly lesser extent compared to cells with wild type NFKBIE (% proliferating cells with wild type and mutated NFKBIE, respectively, cultured without IBR: 90% vs 88%, P=n.s., with 0.2 μM IBR: 57% vs 73%, P&lt;0.001, with 1.0 μM IBR: 28% vs 53%, P&lt;0.001). Consistent with this finding, positive selection of NFKBIE-mutated cells was observed in the presence of IBR after 14 days in mixed culture competition experiments (mean MAF without IBR 47%, with 0.2 μM IBR 61%, p=0.032, with 1.0 μM IBR 64%, p=0.034). The greater resistance of NFKBIE-mutated cells to IBR was further validated by in vivo competition experiments showing a significantly greater increase in MAF in mice treated with IBR compared to controls in all three investigated compartments (n=4 mice/group, PC: P=0.029, blood P=0.029, spleen: P=0.001). To validate these findings in the clinical setting, we investigated the presence of NFKBIE mutations in a cohort of 84 IBR-treated CLL patients. Mutations of NFKBIE were detected at pre-treatment in 10/84 patients, 7/10 with &gt;10% VAF values. Kaplan Meier analysis showed a trend towards reduced progression-free and overall survival from the beginning of IBR treatment for NFKBIE-mutated cases (Figure 1A). Analysis of an extended cohort of over 200 cases is ongoing and will be presented at the meeting. Finally, to investigate whether leukemic cells with mutated NFKBIE remain sensitive to other BCR inhibitors, we tested their growth in the presence of the PI3K inhibitor idelalisib or SYK inhibitor fostamatinib (Figure 1B). In contrast to IBR, both drugs inhibited the proliferation of NFKBIE-mutated cells in vitro, with a greater effect observed with idelalisib. Collectively, these data demonstrate that NFKBIE mutations can reduce the response to IBR treatment and suggest that such cases may benefit more from treatment with a PI3K inhibitor. Figure 1 Figure 1. Disclosures Marasca: Janssen: Honoraria, Other: Travel grants; AstraZeneca: Honoraria; AbbVie: Honoraria, Other: Travel grants. Tafuri: Roche: Research Funding; Novartis: Research Funding; Celgene: Research Funding. Laurenti: Janssen: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Roche: Honoraria, Research Funding; Gilead: Honoraria; BeiGene: Honoraria. Gattei: abbVie: Research Funding; Janssen: Research Funding; Menarini: Research Funding.

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