scholarly journals Β-Catenin and Axl Receptor Tyrosine Kinase Modulation in CLL B-Cells with Co-Culture on Marrow Stromal Cells: Implications for Drug Resistance

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1739-1739
Author(s):  
Sutapa Sinha ◽  
Charla R Secreto ◽  
Justin C. Boysen ◽  
Steven L. Warner ◽  
David J. Bearss ◽  
...  
Keyword(s):  
Drug Resistance ◽  
B Cells ◽  
B Cell ◽  
Receptor Tyrosine Kinase ◽  
Stromal Cells ◽  
Data Safety Monitoring Board ◽  
Marrow Stromal Cells ◽  
B Cell Survival ◽  
Axl Receptor Tyrosine Kinase ◽  
Gsk 3Β

Introduction: Bone marrow stromal cells (BMSCs), a major component of CLL microenvironment influences CLL B-cell survival. We have utilized an in vitro BMSC model system and found unique alterations in CLL B-cells with short term BMSC co-culture that point to previously unidentified biologic changes in the CLL B-cells that may influence CLL B-cell signaling and their drug resistance. Methods: Purified primary CLL B-cells (n=41) from previously untreated CLL patients were cultured alone or co-cultured with primary BMSCs from either normal individuals (n=24) or CLL patients (n=18) at a 50:1 ratio in AIMV medium. After 48 hours, separated CLL B-cells or BMSCs were examined by immunoprecipitation/Western blot analyses to assess the presence of intracellular signal proteins and real time PCR to determine the RNA level expression. In separate experiments to assess CLL B-cell response in co-culture with BMSC, purified CLL B-cells were treated with the following agents at sub lethal doses; fludarabine, chlorambucil, ibrutinib and venetoclax as single agents. Results: Consistent and significant increase in expression of Axl receptor tyrosine kinase for both mRNA and protein levels was observed in CLL B-cells co-cultured with BMSCs compared to CLL B-cells cultured alone. We also detected significantly increased expression of β-catenin at the protein level in CLL B-cells co-cultured with BMSCs. In contrast there was no significant change in β-catenin or Axl protein expression in the co-cultured BMSCs. Co-culturing of CLL B-cells with BMSCs using transwells confirmed that the upregulation of both Axl and β-catenin is dependent on the direct contact of CLL B-cells with BMSCs. Experiments showed that the increased Axl level in co-cultured CLL B-cells was independent of Axl kinase activity. Furthermore, the CLL B-cells from co-culture also had clear upregulation of downstream P-ERK-1/2 but no change in P-AKT(Ser473). Next we reasoned that if increases in Axl and β-catenin are related to drug resistance then CLL B-cells should have increases in those proteins when cultured with drugs and in presence of BMSCs. Treatment with chemotherapeutic or targeted therapy drugs, (i.e. fludarabine, chlorambucil, ibrutinib, venetoclax) with sublethal doses was found to lead to increase in expression levels of both β-catenin and Axl in co-cultured CLL B-cells. However these increases were significantly over that seen with simple co-culture of CLL B-cells with BMSCs. Since CLL B-cells were less sensitive to these latter chemotherapy drugs in presence of BMSCs, this suggests to us a role for both Axl and β-catenin in stromal mediated CLL B-cell drug resistance to these agents. Moreover, high nuclear β-catenin and P-ERK-1/2 levels were also detected in co-cultured CLL B-cells. It is also known that ERK associates with and inactivates GSK-3β resulting in the up-regulation of β-catenin. We found upregulation in P-GSK-3β (Ser9) an inactive molecule which can result in increasing accumulation of β-catenin. Inhibition of P-ERK-1/2 using the ERK inhibitor PD98059 in co-cultured CLL B-cells inhibited β-catenin as well as Axl expression levels. Furthermore, it has been shown that Axl expression can be regulated by c-Jun activity. In that regard we have observed upregulation of P-c-Jun(Ser73) which can enhance Axl level in co-cultured CLL B-cells and inhibition of c-Jun activity using SP600125 (c-jun upstream JNK inhibitor), as well inhibited the Axl expression. Finally, we studied 5 CLL patients before and while being treated with ibrutinib/chemo-immuno therapy for the expression of CLL B-cell Axl, β-catenin, P-ERK-1/2, P-c-Jun(Ser73) levels. We found that 2 patients had increase in Axl expression, 4 patients had increased β-catenin and P-ERK-1/2 levels and 3 patients showed increase in P-c-Jun(S73) level after the therapy. Conclusion: Here we show that marrow stromal cell contact with CLL B-cells consistently mediate increased expression in both β-catenin and Axl in CLL B-cells (Figure1). The mechanism for this may, in part, via activated ERK and c-Jun levels (Figure1). We believe that these changes in both molecules are associated with leukemic B-cell survival and drug resistance (Figure1). These studies suggest that a further understanding of the roles of Axl and β-catenin in the CLL B-cells mediated by contact with BMSC will help to develop potential strategies for the management of CLL disease resistant to various drugs. Disclosures Warner: Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment. Kay:Agios: Other: DSMB; Infinity Pharmaceuticals: Other: DSMB; Celgene: Other: Data Safety Monitoring Board; MorphoSys: Other: Data Safety Monitoring Board.

scholarly journals Enhanced Expression of Beta-Catenin and Axl Receptor Tyrosine Kinase (RTK) in Chronic Lymphocytic Leukemia (CLL) B-Cells with Co-Culture on Marrow Stromal Cells: Implications for Leukemic Cell Drug Resistance

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3125-3125
Author(s):  
Sutapa Sinha ◽  
Charla R Secreto ◽  
Justin C. Boysen ◽  
Steven L. Warner ◽  
David J. Bearss ◽  
...  
Keyword(s):  
Drug Resistance ◽  
B Cells ◽  
B Cell ◽  
Board Of Directors ◽  
Stromal Cells ◽  
Research Funding ◽  
Advisory Committees ◽  
Expression Levels ◽  
B Cell Survival ◽  
Gsk 3Β

Abstract Introduction CLL remains an incurable disease and represents a significant health problem in the western world. Increasing evidence highlights that the impact of marrow stromal cells is a key component influencing CLL B-cell survival. We have utilized an in vitro bone marrow stromal cell (BMSC) model system and found unique alterations in CLL B-cells with BMSC co-culture that point to previously unidentified biologic changes in the CLL B-cells that may influence CLL B-cell signaling and drug resistance. Methods Purified primary CLL B-cells (n= 39) from previously untreated CLL patients were cultured alone or co-cultured with primary BMSCs from either normal individuals (n=26) or CLL patients (n=17) at a 50:1 ratio in AIMV medium. After 48 hours, separated CLL B-cells or BMSCs were examined by immunoprecipitation/Western blot analyses and where needed real time PCR was done to assess the presence of intracellular proteins. In separate experiments to assess CLL B-cell killing, purified CLL B-cells were treated with TP-0903, fludarabine, chlorambucil and ibrutinib as single agents with or without BMSC co-culture. Results We observed significant increases in expression of Axl for both mRNA and protein levels in CLL B-cells co-cultured with BMSCs compared to CLL B-cells cultured alone. We also detected significantly increased expression of β-catenin at the protein level in CLL B-cells co-cultured with BMSC. But, we did not see any significant change in β-catenin or Axl protein expression in BMSCs co-cultured with CLL B-cells. Co-culturing of CLL B-cells with BMSCs using transwells confirmed that the upregulation of both Axl and β-catenin is dependent on the direct contact of CLL B-cells with BMSCs. The CLL B-cells from co-culture also had upregulation in phosphorylated (P)-ERK-1/2 but no change in P-AKT(Ser473). High nuclear β-catenin and P-ERK-1/2 levels were also detected in co-cultured CLL B-cells. ERK associates with and inactivates GSK-3β resulting in the up-regulation of β-catenin. We next checked for P-GSK-3β (Ser9) in co-cultured CLL B-cells. Upregulation in P-GSK-3β (Ser9) detected in co-cultured CLL B-cells suggests inactivation of GSK-3β and increasing β-catenin accumulation in co-cultured CLL B-cells. Moreover, inhibition of P-ERK-1/2 with inhibitor PD98059 in CLL B-cells cultured with BMSCs inhibited β-catenin as well as Axl expression levels. We also determined the phosphorylation status of Axl in CLL B-cells in co-culture with BMSC but found no change either at Y702 (Axl kinase domain) or total tyrosine phosphorylation levels for Axl in CLL B-cells. Thus, we assume that the role of Axl in co-cultured leukemic B-cells is independent of its kinase activity. Next we determined the effect of the highly specific Axl inhibitor TP-0903 on CLL B-cell status of Axl and b-catenin while in BMSC co-culture. Interestingly, both Axl and β-catenin protein expression levels were found to be further upregulated in CLL B-cells exposed to sub-lethal doses of TP-0903 in co-culture with BMSC. Treatment with chemotherapeutic or targeted therapy drugs, (i.e. fludarabine, chlorambucil or ibrutinib) also led to increase in expression levels of both β-catenin and Axl CLL B-cells co-cultured with BMSC. Of interest CLL B-cells were less sensitive to the chemotherapy drugs in presence of BMSCs, suggesting a role for both Axl and β-catenin in stromal mediated CLL B-cell drug resistance to these agents. This was not true for the Axl inhibitor as TP-0903 was able to induce robust cell death by targeting P-Axl and overcome BMSC mediated protection even in the presence of increased Axl and b-catenin. We also found that TP-0903 decreased P-Axl as well as the Axl downstream mediator, P-Akt(S473) and reduced Mcl-1 expression in CLL B-cells in BMSC co-culture. Conclusions Here we show that marrow stromal cell mediated increased expression in both β-catenin and Axl in CLL B-cells is associated with leukemic B cell survival and drug resistance. The mechanism for this may in part be via activated ERK levels that also occur when CLL B-cells contact BMSC. The BMSC resistance appears to be more profound for chemotherapeutic agents since Axl inhibitor can still induce CLL B-cell killing with BMSC co-culture. These studies suggest that a further understanding of the roles of Axl and β-catenin in the resistance status of CLL B-cells mediated by contact with BMSC are warranted. Disclosures Warner: Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals, Inc: Employment. Kay:Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Cytomx Therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; 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; Acerta: Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios Pharm: 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; Janssen: Membership on an entity's Board of Directors or advisory committees.

scholarly journals B Cell–Activating Factor Promotes B Cell Survival in Ectopic Lymphoid Tissues in Nasal Polyps

2021 ◽  
Vol 11 ◽  
Author(s):  
Zhe-Zheng Wang ◽  
Jia Song ◽  
Hai Wang ◽  
Jing-Xian Li ◽  
Qiao Xiao ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
Stromal Cells ◽  
Caspase 3 ◽  
Lymphoid Tissues ◽  
B Cell Activating Factor ◽  
B Cell Survival ◽  
Active Caspase

Ectopic lymphoid tissues (eLTs) characterized by B cell aggregation contribute to the local immunoglobulin production in nasal polyps (NPs). B cell-activating factor (BAFF) is vital for B cell survival, proliferation, and maturation. The purpose of this study is to investigate whether BAFF is involved in the B cell survival and eLT formation in NPs. The mRNA and protein levels of BAFF in NP tissues with and without eLTs were detected by PCR and ELISA assay, respectively. The cellular sources of BAFF and active caspase-3-positive B cells in NPs were studied by immunofluorescence staining. B cells purified from NP tissues were stimulated with BAFF and were analyzed by flow cytometry. Stromal cells purified from NP tissues were stimulated with lymphotoxin (LT) α1β2, and BAFF levels in culture supernatants were analyzed by ELISA. Compared with those in control tissues and NPs without eLTs, the BAFF levels were elevated in NPs with eLTs. Abundant BAFF-positive cells and few active caspase-3-positive apoptotic B cells were found in NPs with eLTs, in contrast to those in NPs without eLTs. There was a negative correlation between the numbers of BAFF-positive cells and frequencies of apoptotic B cells in total B cells in NP tissues. BAFF protected nasal polyp B cells from apoptosis in vitro. Stromal cells were an important cellular source of BAFF in NPs with eLTs. LTα1β2 induced BAFF production from nasal stromal cells in vitro. We propose that BAFF contribute to eLT formation in NPs by promoting B cell survival.

scholarly journals Plasma cells induce apoptosis of pre-B cells by interacting with bone marrow stromal cells

Blood ◽  
1996 ◽  
Vol 87 (8) ◽  
pp. 3375-3383 ◽  
Author(s):  
T Tsujimoto ◽  
IA Lisukov ◽  
N Huang ◽  
MS Mahmoud ◽  
MM Kawano
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
Cell Lines ◽  
Stromal Cells ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
B Cell Survival

By using two-color phenotypic analysis with fluorescein isothiocyanate- anti-CD38 and phycoerythrin-anti-CD19 antibodies, we found that pre-B cells (CD38+CD19+) signifcantly decreased depending on the number of plasma cells (CD38++CD19+) in the bone marrow (BM) in the cases with BM plasmacytosis, such as myelomas and even polyclonal gammopathy. To clarify how plasma cells suppress survival of pre-B cells, we examined the effect of plasma cells on the survival of pre-B cells with or without BM-derived stromal cells in vitro. Pre-B cells alone rapidly entered apoptosis, but interleukin-7 (IL-7), a BM stromal cell line (KM- 102), or culture supernatants of KM-102 cells could support pre-B cell survival. On the other hand, inhibitory factors such as transforming growth factor-beta1 (TGF-beta1) and macrophage inflammatory protein- 1beta (MIP-1beta) could suppress survival of pre-B cells even in the presence of IL-7. Plasma cells alone could not suppress survival of pre- B cells in the presence of IL-7, but coculture of plasma cells with KM- 102 cells or primary BM stromal cells induced apoptosis of pre-B cells. Supernatants of coculture with KM-102 and myeloma cell lines (KMS-5) also could suppress survival of pre-B cells. Furthermore, we examined the expression of IL-7, TGF-beta1, and MIP-1beta mRNA in KM-102 cells and primary stromal cells cocultured with myeloma cell lines (KMS-5). In these cells, IL-7 mRNA was downregulated, but the expression of TGF- beta1 and MIP-1beta mRNA was augmented. Therefore, these results suggest that BM-derived stromal cells attached to plasma (myeloma) cells were modulated to secrete lesser levels of supporting factor (IL- 7) and higher levels of inhibitory factors (TGF-beta1 and MIP-1beta) for pre-B cell survival, which could explain why the increased number of plasma (myeloma) cells induced suppression of pre-B cells in the BM. This phenomenon may represent a feedback loop between pre-B cells and plasma cells via BM stromal cells in the BM.

Crosstalk between Chronic Lymphocytic Leukemia (CLL) B-Cells and Marrow Stromal Cells: Implication for CLL B-Cell Activation and Survival.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 337-337
Author(s):  
Wei Ding ◽  
Grzegorz S. Nowakowski ◽  
Jennifer L. Abrahamzon ◽  
Linda E. Wellik ◽  
Asish K. Ghosh ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
Growth Factor ◽  
B Cell ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Marrow Stromal Cells ◽  
Drug Induced ◽  
Cd38 Expression ◽  
The Mean

Abstract It is believed that malignant cells “condition” the microenvironment to facilitate tumor cell survival. We hypothesized that crosstalk between CLL B-cells and marrow stromal cells impacts both cell types bi-directionally and ultimately contributes to leukemic cell apoptotic resistance. To test this hypotheses, bone marrow stromal cells from core bone biopsies from CLL patients were isolated and cultured using methods we have previously described (Leuk Res 2007 31(7):899). Subsequently, we determined the impact of co-culture on CLL B-cell features including apoptosis and CD38 expression. In addition, we evaluated the release of angiogenic cytokines on co-culture and signal events in the stromal cells. Immunophenotyping demonstrated that cultured bone biopsy derived stromal cells were CD73+, CD105+, CD146+, CD14−, CD45−, CD34−, HLA-DR-, suggesting they were mesenchymal stem cells (MSC). Co-culture of these MSC with CLL B-cells protected CLL B-cells from both spontaneous apoptosis (SA) and drug-induced (fludarabine and chlorambucil) apoptosis (DA). For SA, the mean survival of CLL B-cells with or without co-culture of MSC for 5 days were 56.9 ± 10.0 and 7.7 ±3.7 (p<0.05), respectively. When CLL B cells were treated with fludarabine or chlorambucil, the fraction of CLL cells tightly adherent to MSC (TA-CLL) showed higher survival than a less adherent but viable fraction of CLL B-cells. The mean survival of TA-CLL cells treated with 10 μM of fludarabine for 48 hours in the presence of MSC were 67.5 ± 3.6 vs 29.8 ± 11.1 without MSC (P<0.05), respectively. When CLL cells with evidence for CD38 expression were co-cultured with MSC, both the percentage of CD38 positive cells and level of expression of CD38 per cell were up-regulated (mean fold change: CD38 percentage, 2.7, p<0.05; CD38 MFI, 1.9, p<0.05) after 2 weeks. In contrast, the CD38 percentage and expression were not changed in cells with minimal CD38 expression when these CLL B-cells were co-cultured with MSC. In addition, co-culture of MSC with CLL cells induced rapid ERK and AKT phosphorylation (within 30 min) in the MSC on immunoblot analysis. When CLL B cells and MSCs were cultured in transwells, the activation of ERK and AKT in MSC occurred at similar levels, indicating that activation of MSC was mediated by soluble factors. In addition, co-culture led to increased secretion of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) as well as a decrease of thrombospondin-1 (TSP-1) in the culture medium. These findings confirm that co-culture of CLL B-cells and MSC culminates in “angiogenic switch.” Taken together, these results strongly suggest interactions between MSC and CLL B cells are a bi-directional process. In leukemic cells, the interaction not only protects against spontaneous and drug induced apoptosis but also leads to an increase in CD38 expression consistent with an activated status. In MSC, the interaction leads to activation of ERK and AKT. Co-culture also facilitates angiogenic switching. These results underscore the dynamic and complex nature of the interactions between bone marrow stromal cells and CLL B-cells. Further studies are needed to dissect how crosstalk between CLL B-cells and MSC relates to disease progression, and determines whether these interactions can be targeted with therapeutic intent.

scholarly journals Bone marrow stromal cells modulate both kappa light chain and Ly1 antigen expression on Ly1+ pre-B cell lines in vitro

Blood ◽  
1990 ◽  
Vol 76 (2) ◽  
pp. 383-392 ◽  
Author(s):  
MG Kruger ◽  
RL Riley ◽  
EA Riley ◽  
JM Elia
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Marrow Stromal Cells ◽  
Light Chains ◽  
Bone Marrow Cultures ◽  
Marrow Cultures

Abstract Murine Ly1+ pre-B cell lines, including 70Z/3 and three pre-B cell lines derived from long-term bone marrow cultures, exhibited selective adherence to bone marrow stromal cells. In contrast, splenic B cells, the A20 B-cell lymphoma, and four Ly1- B cell lines derived from long- term bone marrow cultures failed to adhere substiantially to bone marrow cultures failed to adhere substiantially to bone marrow stroma. Ly1+ pre-B cell lines were induced to express kappa light chains by exposure to either lipopolysaccharide (LPS), recombinant interleukin-1 (IL-1), or stromal cells. However, induction of kappa light chains failed to prevent pre-B cell adherence to stromal cells. Supernatants derived from primary bone marrow stromal cells decreased Ly1 expression on the Ly1+ pre-B cell lines. These experiments suggest that (1) expression of immunoglobulin light chains by developing Ly1+ pre-B cells is mediated by bone marrow stromal cells; (2) loss of specific adherence to stroma is progressive and occurs post-light chain induction; and (3) soluble products of stromal cells may downregulate expression of surface Ly1 on otherwise Ly1+ pre-B cells. The importance of these observations to the development of both the Ly1- and Ly1+ B cell lineages in the mouse is discussed.

Rooting into the Soil, a Model for the Role of Sox4 in Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3794-3794
Author(s):  
Saradhi Mallampati ◽  
Baohua Sun ◽  
Yun Gong ◽  
Enze Wang ◽  
M. James You ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Leukemic Cell ◽  
Marrow Stromal Cells ◽  
Leukemic Cells ◽  
Cell Stage

Abstract Development and progression of leukemia requires interaction of leukemia-initiating cells with their bone marrow niches. The niches serve as the nursery and shelter for the leukemic cells, which can result in drug resistance, disease recurrence, and minimal residual disease, the most important causes for the death of patients with leukemia. Therefore, obliteration of the interaction between the leukemic cells and their niches is of utmost importance in eradicating leukemic cells during therapy to cure the disease. However, little is currently known of the molecular mechanisms underlying the interaction of the two types of cells. Sox4, a SRY-related HMG-box containing transcription factor that is vital during development, plays an important role in leukemia. Published mouse studies demonstrated that increased expression of Sox4 was associated with leukemogenesis. We determined the expression levels of Sox4 by real-time RT-PCR in 100 human leukemic samples and found high levels of expression in B- and T-ALL, but not in AML, CML, CLL, Sezary syndrome, or T cell prolymphocytic leukemia. In accordance, 7 of the 8 ALL cell lines (the exception was 697) we tested showed high expression levels of Sox4, but AML cell lines, normal mature B cells, T cells, and bone marrow CD34+ cells had low levels of expression. Since the majority of clinical B-ALL cases correspond to the pre-B cell stage, we investigated the role of Sox4 in a pre-B cell line (Nalm6) by lentivirus-mediated RNAi. Remarkably, knockdown of Sox4 in Nalm6 cells caused 70% reduction in the formation of leukemic cell clusters under the monolayer of co-cultured M2-10B4 bone marrow stromal cells, a phenomenon known as pseudo-emperipolesis. Similar results were obtained with ex vivo cultured bone marrow cells from conditional Sox4 knockout mice that displayed B cell developmental arrest at the transition from pro-B to pre-B cell stage and an absence of pre-B cells. These findings suggested that Sox4 is required for the interaction of the developing B cells or leukemic cells with bone marrow stromal cells, a component of the bone marrow niche. Since CXCR4/SDF1-mediated “homing” is known to be required for pseudo-emperipolesis, we tested the effect of Sox4 on Nalm6 cell migration toward SDF1 gradient and found that Sox4 did not affect the migration, suggesting that Sox4 is not acting through “homing”. Instead, our data indicated that the role of Sox4 in the interaction of leukemic cells with stromal cells is most likely mediated by its ability in enhancing the adhesion of the leukemic cells because we found that lentivirus-medicated overexpression of Sox4 in the 697 B cell line caused the suspension cells to display a spindle and adhesive morphology. In addition, 21% of the putative Sox4 downstream genes that we identified by multiple sets of gene expression microarray experiments are known to be involved in cell adhesion. Moreover, we found that the changes in gene expression profile of leukemic cells upon Sox4 knockdown or overexpression significantly overlap with the changes in response to the presence of bone marrow stromal cells in co-culture, indicating that Sox4 pathways are involved in leukemic cell response to stromal cell signaling. Based on these findings we hypothesize that deletion of Sox4 abolishes the interaction between the developing lymphocytes and their niches during lymphopoiesis. Conversely, overexpression of Sox4 may enforce these cells to over-interact with the niches so that they are overexposed to local growth factor stimuli. If superimposed with other genetic and/or epigenetic changes in the developing lymphocytes, such over-interaction may result in the development of leukemia. In case of established leukemia, such over-interaction may lead to the enhanced protection of leukemic cells by their niches. Therefore, the role of Sox4 in the interaction of developing lymphocytes or leukemic cells with their niches is like “rooting into the soil” of a growing tree, abbreviated as “rooting”.

scholarly journals Circulating microvesicles in B-cell chronic lymphocytic leukemia can stimulate marrow stromal cells: implications for disease progression

Blood ◽  
2010 ◽  
Vol 115 (9) ◽  
pp. 1755-1764 ◽  
Author(s):  
Asish K. Ghosh ◽  
Charla R. Secreto ◽  
Traci R. Knox ◽  
Wei Ding ◽  
Debabrata Mukhopadhyay ◽  
...  
Keyword(s):  
B Cells ◽  
Tumor Microenvironment ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Disease Progression ◽  
Stromal Cells ◽  
Lymphocytic Leukemia ◽  
Marrow Stromal Cells ◽  
Akt Activation ◽  
Cell Chronic Lymphocytic Leukemia

Abstract Microvesicles (MVs) released by malignant cancer cells constitute an important part of the tumor microenvironment. They can transfer various messages to target cells and may be critical to disease progression. Here, we demonstrate that MVs circulating in plasma of B-cell chronic lymphocytic leukemia (CLL) patients exhibit a phenotypic shift from predominantly platelet derived in early stage to leukemic B-cell derived at advanced stage. Furthermore, the total MV level in CLL was significantly greater compared with healthy subjects. To understand the functional implication, we examined whether MVs can interact and modulate CLL bone marrow stromal cells (BMSCs) known to provide a “homing and nurturing” environment for CLL B cells. We found that CLL-MV can activate the AKT/mammalian target of rapamycin/p70S6K/hypoxia-inducible factor-1α axis in CLL-BMSCs with production of vascular endothelial growth factor, a survival factor for CLL B cells. Moreover, MV-mediated AKT activation led to modulation of the β-catenin pathway and increased expression of cyclin D1 and c-myc in BMSCs. We found MV delivered phospho-receptor tyrosine kinase Axl directly to the BMSCs in association with AKT activation. This study demonstrates the existence of separate MV phenotypes during leukemic disease progression and underscores the important role of MVs in activation of the tumor microenvironment.

TC-PTP–deficient bone marrow stromal cells fail to support normal B lymphopoiesis due to abnormal secretion of interferon-γ

Blood ◽  
2007 ◽  
Vol 109 (10) ◽  
pp. 4220-4228 ◽  
Author(s):  
Annie Bourdeau ◽  
Nadia Dubé ◽  
Krista M. Heinonen ◽  
Jean-François Théberge ◽  
Karen M. Doody ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Marrow Stromal Cells ◽  
Bone Marrow Stroma ◽  
B Lymphopoiesis ◽  
Marrow Stroma ◽  
Ifn Γ

Abstract The T-cell protein tyrosine phosphatase (TC-PTP) is a negative regulator of the Jak/Stat cytokine signaling pathway. Our study shows that the absence of TC-PTP leads to an early bone marrow B-cell deficiency characterized by hindered transition from the pre-B cell to immature B-cell stage. This phenotype is intrinsic to the B cells but most importantly due to bone marrow stroma abnormalities. We found that bone marrow stromal cells from TC-PTP−/− mice have the unique property of secreting 232-890 pg/mL IFN-γ. These high levels of IFN-γ result in 2-fold reduction in mitotic index on IL-7 stimulation of TC-PTP−/− pre-B cells and lower responsiveness of IL-7 receptor downstream Jak/Stat signaling molecules. Moreover, we noted constitutive phosphorylation of Stat1 in those pre-B cells and demonstrated that this was due to soluble IFN-γ secreted by TC-PTP−/− bone marrow stromal cells. Interestingly, culturing murine early pre-B leukemic cells within a TC-PTP–deficient bone marrow stroma environment leads to a 40% increase in apoptosis in these malignant cells. Our results unraveled a new role for TC-PTP in normal B lymphopoiesis and suggest that modulation of bone marrow microenvironment is a potential therapeutic approach for selected B-cell leukemia.

scholarly journals Normal B Cell Homeostasis Requires B Cell Activation Factor Production by Radiation-resistant Cells

2003 ◽  
Vol 198 (6) ◽  
pp. 937-945 ◽  
Author(s):  
Leonid Gorelik ◽  
Kevin Gilbride ◽  
Max Dobles ◽  
Susan L. Kalled ◽  
Daniel Zandman ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
Stromal Cells ◽  
Cell Activation ◽  
B Cell Activation ◽  
B Cell Survival ◽  
Activation Factor ◽  
Radiation Resistant ◽  
B Cell Homeostasis

The cellular source of B cell activation factor (BAFF) required for peripheral B cell survival/maturation is unknown. To determine the nature of BAFF-producing cells we established and analyzed reciprocal bone marrow (BM) chimeras with wild-type (WT) and BAFF-deficient mice. The results revealed that BAFF production by radiation-resistant stromal cells is completely sufficient to provide a necessary signal for B cell survival/maturation, as BAFF−/− BM cells transferred into lethally irradiated WT mice gave rise to normal numbers of follicular (FO) and marginal zone (MZ) B cell subpopulations. On the other hand, transfer of WT BM into BAFF−/− lethally irradiated mice resulted only in minimal reconstitution of mature FO B cells and no restoration of MZ B cells. Thus, in the absence of BAFF+/+ stromal cells, BAFF production by BM-derived cells, presumably by macrophages, dendritic cells, and/or neutrophils, was not at all sufficient to support normal B cell homeostasis. Interestingly, immunization of both types of chimeras stimulated high levels of antigen-specific antibody secretion, indicating that either stromal cell– or hematopoietic cell–derived BAFF is sufficient for B cell antibody responses.

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