Phosphatidylinositol 3-kinase inhibition down-regulates survivin and facilitates TRAIL-mediated apoptosis in neuroblastomas

Background/purpose

Recent findings have correlated neuroblastoma development with aberration of apoptosis. In particular, increased levels of survivin, a member of the inhibitor of apoptosis protein (IAP) family, have been associated with increased resistance to apoptosis in neuroblastomas. The purpose of this study was to determine whether the phosphatidylinositol 3-kinase (PI3K)/Akt pathway can alter the expression of survivin and facilitate tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis in neuroblastoma cells.

Methods

Human neuroblastoma cells (SK-N-SH, BE[2]C, LAN-1 and IMR-32) were treated with LY294002 or wortmannin, inhibitors of PI3K, for 24 hours. Transient transfection of a dominant negative PI3K expression plasmid, pCGNN-Δp85, was performed to inhibit PI3K activation. Cells were treated with TRAIL, caspase-3, or pan-caspase inhibitors. RNase protection assay was performed to assess mRNA changes in IAP family members, including survivin. Western blot analysis was performed to measure changes in the levels of procaspases and survivin. Apoptosis was assessed by a DNA fragmentation ELISA assay.

Results

The authors found that survivin and cIAP1 mRNA as well as protein expression were decreased after PI3K inhibition. Combination treatment with LY294002 and TRAIL increased apoptosis of SK-N-SH cells compared with TRAIL alone; these results were further corroborated by complete inhibition of apoptosis by caspase-3 or pan-caspase inhibitor.

Conclusions

The authors report that PI3K pathway inhibition down-regulates survivin expression and enhances TRAIL-mediated apoptosis in neuroblastomas. PI3K pathway may play a crucial role in neuroblastoma cell survival; therefore, treatment with inhibitors of PI3K may provide potential novel therapeutic options.     

Profiling of nuclear extract proteins from human neuroblastoma cell lines: the search for fingerprints

Purpose

Neuroblastoma (NB) commonly presents with advanced disease at diagnosis and is associated with poor survival. If identified early, however, survival is improved suggesting a benefit of early detection. The authors have used proteomics technology in an attempt to identify novel markers that permit early detection of NB and characterize its molecular makeup.

Methods

Three different human NB cell lines SK-N-AS, SK-N-DZ, and SK-N-FI were subjected to series of biochemical fractionation steps to extract nuclear proteins. These proteins were analyzed for differential expression by 2-dimensional polyacrylamide gel electrophoresis. Polypeptides of interest were subsequently identified by liquid chromatography-linked tandem mass spectrometry.

Results

Multiple proteins were identified in these human NB cell lines including SET (a ubiquitous nuclear protein), stathmin (a cytosolic signal transduction protein), and grp94 (a heat shock protein). SET is a putative oncogene associated with the chromosomal translocation (6;9) leading to acute undifferentiated leukemia. Stathmin is an oncogene found in greater abundance in leukemic cells compared to nonleukemic cells. A total of 94-kDa glucose-regulated protein has been shown to be protective in human breast cancer cells in vitro and related with the occurrence, differentiation, and progression of human lung cancer. The first protein has not been previously associated with NB.

Conclusions

The identification of these 3 previously unrecognized cancer-related potential biomarkers in human NB cell lines may prove useful in developing diagnostic tests. The proteomic methodology of 2-dimensional polyacrylamide gel electrophoresis/mass spectrometry also provides an improved opportunity to understand the natural history of NB and develop novel chemotherapeutic agents for this prevalent childhood malignancy with a dismal outcome.     

Neuroblastoma detection using serum proteomic profiling: a novel mining technique for cancer?

Background

Serum proteins in neuroblastoma (NB), such as neuron-specific enolase and lactate dehydrogenase, are used as nonspecific markers of disease severity. In this study, we have generated serum protein profiles that correlate with NB by applying proteomic technologies to uncover, at the protein level, serum polypeptide expression patterns in patients with NB.

Methods

Surface-enhanced laser desorption/ionization-time-of-flight mass spectrometry was used to generate protein expression spectra in human NB (group I, n = 18) and healthy children (group II, n = 17) sera. Groups I and II mass spectral data were compared after baseline subtraction. Peaks with high signal-to-noise ratios were selected and grouped into bins with various intervals along mass-to-charge axis. Two-sample t test and 3-fold cross validation were used to identify differential biomarkers between groups I and II.

Results

Significant differentially expressed proteins were identified between groups I and II (P ≤ .05). The discriminatory features (proteomic patterns) of cancer from normal sera were successfully identified using the classification algorithm. The average classification performance after 3-fold cross validation was 87.26%.

Conclusion

Surface-enhanced laser desorption/ionization-time-of-flight mass spectrometry is suitable for preliminary assessment of NB and could potentially provide a noninvasive diagnosis of NB. We propose that surface-enhanced laser desorption/ionization provides a novel method for NB diagnosis because direct observations of spectral differences between normal and NB sera are possible.     

Neuroblastoma cells inhibit the immunostimulatory function of dendritic cells

Purpose

Dendritic cells (DC) are critical for induction of antitumor immunity. Recent studies suggest that tumors may avoid immune destruction by inhibiting DC function. The authors investigated the effect of neuroblastoma (NB) on surface antigen expression and T cell activation by DCs.

Methods

DCs were generated in the presence of granulocyte and macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4) from peripheral blood of healthy donors. On day 6 of culture, DCs were exposed to human NB cells and were analyzed by flow cytometry.

Results

The proinflammatory cytokine tumor necrosis factor alpha (TNF-α) failed to upregulate the expression of HLA-DR and costimulatory molecule CD86 by DCs that were cultured with NB. Conversely, upregulation was preserved when DCs were cultured in the absence of NB. Exposure to NB also led to apoptosis of DCs as shown by 2-fold increase in surface phosphatidylserine. It appears that direct contact was required to inhibit DC maturation, because DCs separated from NB cells using a transwell insert did not suppress surface antigen expression. Finally, DCs exposed to NB inhibited the proliferation of allogeneic T cells in mixed lymphocyte reactions.

Conclusions

These findings have significant implications for tumor-pulsed DC vaccines in the treatment of NB and suggest a mechanism by which NB escape rejection.     

Interferon-gamma induces caspase-8 in neuroblastomas without affecting methylation of caspase-8 promoter

Background

The expression of caspase-8, a cysteine protease that is crucial for the apoptotic cascade, is absent in a high percentage of neuroblastomas, the most frequent extracranial solid tumor of infants and children. Resistance of neuroblastomas to death-receptor (eg, tumor necrosis factor alpha (TNF-α) receptor)—mediated apoptosis is thought to be caused by loss of caspase-8 expression. Gene silencing by hypermethylation of caspase-8 promoter has been proposed for the loss of caspase-8 expression in neuroblastoma cells.

Methods

To further evaluate the role of caspase-8 in neuroblastoma, we assessed the induction of caspase-8 expression in neuroblastoma cells by treating the cells with a physiologic agent such as interferon-γ.

Results

The authors found that interferon-γ induces caspase-8 expression in neuroblastoma cells irrespective of the gene silenced by hypermethylation of caspase-8 promoter. The authors show that interferon-γ also regulates other apoptosis related gene expression. Moreover, they show that interferon-γ treatment in combination with TNF-α decreases neuroblastoma cell proliferation.

Conclusions

Interferon-γ induces procaspase-8 expression in neuroblastoma cells, and this induction is not dependent on demethylation of the caspase-8 promoter. Therapies aimed at inducing caspase-8 expression by adjunctive treatment, such as interferon-γ, may increase the effectiveness of current chemotherapeutic regimens.     

Isolation and characterization of a DNA synthesome from a neuroblastoma cell line

Background

Despite significant analysis of the chromosomal abnormalities associated with neuroblastoma (NB), the role that NB DNA replication may play in the accumulation of genetic damage is poorly understood. For that matter, the mechanisms involved in NB DNA synthesis have yet to be elucidated. In an effort to investigate this process in NB, we have isolated and purified a multiprotein DNA replication complex from human NB cells (IMR-32).

Methods

Using a series of subcellular fractionations, ion-exchange chromatography, and gradient sedimentation steps, we have isolated a simian virus 40 replication competent multiprotein complex from IMR-32 NB cells, which has been designated the DNA synthesome. Enzymatic and immunodetection techniques were used to characterize the multiple components of the multiprotein DNA replication complex.

Results

The NB DNA synthesome was found to remain intact and functional through all the steps of its purification. The proteins and enzymatic activities that were found to copurify with the NB DNA synthesome include: DNA polymerases α, δ, and ?, proliferating cell nuclear antigen, replication factor A, replication factor C, topoisomerases I and II, flap endonuclease 1, and DNA ligase I.

Conclusion

Although the cooperative integration of a DNA replication macromolecular complex (DNA synthesome) is not new, we extend the view of the DNA synthesome mediating DNA synthesis for human NB. The data reported here characterize the human NB DNA synthesome for the first time and provide the groundwork for investigating whether the NB DNA synthesome contributes to faulty DNA replication and tumor pathogenesis for this childhood malignancy.     

Differential sensitivity of chemoresistant neuroblastoma subtypes to MAPK-targeted treatment correlates with ERK, p53 expression, and signaling response to U0126

Purpose

Neuroblastoma tumors are comprised of neuroblastic (N), substrate-adherent (S), and intermediate (I) cells. Because cell growth and differentiation often involve p44/p42 mitogen-activated protein kinase (MAPK) pathway signaling, we explored MAPK signaling and growth response in three NB cell types after MAPK kinase (MEK) inhibition to evaluate the feasibility of MAPK-targeted treatment strategies.

Methods

Three human NB cell cultures, SH-SY5Y (N-type), BE(2)-C (I-type), and SK-N-AS (S-type), were treated in monolayer cultures with increasing concentrations of the MEK inhibitor U0126. MAPK pathway intermediates MEK and ERK, their activated (phosphorylated) forms p-MEK and p-ERK, and p53 expression were assessed by Western blot at 1 and 24 hours. At 72 hours, cell counts determined growth inhibition and DNA fragmentation ELISA assessed apoptosis.

Results

Among all three lines, total ERK and MEK expression were unaffected by U0126. However, constitutive total ERK and p53 expression were significantly greater in BE(2)-C (I-type) cells than in SH-SY5Y (N-type) and SK-N-AS (S-type). Active ERK (p-ERK) levels decreased in dose response to U0126 at 1 and 24 hours in all lines. Conversely, p-MEK levels increased with increasing U0126 concentrations at 1 hour in SH-SY5Y (N-type) and at 24 hours in all lines. BE(2)-C (I-type) cell counts decreased in concentration-dependent fashion with U0126, whereas SH-SY5Y (N-type) and SK-N-AS (S-type) showed a biphasic response with increased cell counts at 1 μmol/L U0126 and slightly decreased cell counts at 10 μmol/L U0126.

Conclusion

This study demonstrates that BE(2)-C (I-type) cells exhibit greater constitutive total ERK and p53 expression than SH-SY5Y (N-type) and SK-N-AS (S-type). Although all three lines exhibit p-ERK decreases with MEK inhibition, only BE(2)-C (I-type) cells significantly decrease their proliferation with U0126 treatment. Although MEK inhibition holds promise in targeting I-type NB cells, successfully treating this heterogeneous tumor may require combining agents against N- and S-type cells.     

Structural analysis of the human neuroblastoma DNA replication complex: insights into faulty proliferation

Background

Whether faulty DNA synthesis contributes to neuroblastoma (NB) pathogenesis has received little attention. We have shown that NB DNA replication is orchestrated by a multiprotein DNA replication complex (DNA synthesome) which mediates error-prone DNA synthesis. We sought to define proteomic alterations of the NB DNA synthesome, which lead to lowered replication fidelity.

Methods

DNA synthesomes from NB and neural stem (NS) cell culture were purified. Proteomic differences of the DNA synthesome between NB and NS cells were determined using 2-dimensional polyacrylamide gel electrophoresis and immunodetection.

Results

DNA synthesome proteins from NB and NS cells were compared. Only replication protein A (RPA) showed distinct changes. RPA from NS cells resolved as a single spot (isoelectric point [pI] 5.75), whereas RPA in NB showed a main spot (pI 5.75) along with 3 additional isoforms. RPA binds to single-stranded DNA and participates in protein-protein interactions.

Conclusions

NB DNA synthesome showed 3 distinct isoforms of RPA when compared with NS cells. These findings are significant in that it is possible to link changes in the fidelity of DNA replication with a specific protein alteration of the NB DNA synthetic apparatus. The novel RPA forms may be a new signature of NB malignancy.     

Novel peptides secreted from human neuroblastoma: useful clinical tools?

Background

Differentially expressed neuroblastoma (NB) proteins are vital for the development of new diagnostics and therapeutics. For example, secretory NB peptides (neuron-specific enolase and chromogranins) are clinically useful. We investigated polypeptide secretion by employing proteomic technologies to analyze proteins released from cultured NB cells.

Methods

Neuroblastoma cell lines (SK-N-AS, SK-N-DZ, and SK-N-FI) were grown in serum-free media. Conditioned media from each cell line was analyzed for secreted proteins by 2-dimensional polyacrylamide gel electrophoresis. Selected polypeptides were identified by liquid chromatography-linked tandem mass spectrometry.

Results

We identified 5 polypeptides that were secreted or shed by NB. Ubiquitin, β₂-microglobulin, insulin-like growth factor binding protein-2, superoxide dismutase (copper and zinc), and heat shock cognate 70-kd proteins were secreted from NB cells, as compared with control media. Elevated levels of these proteins have been described in serum/tissues under intracellular stress and malignancies, including NB.

Conclusion

These novel secretory polypeptides may contribute to NB growth. The proteins may reveal additional tumor markers and permit putative use in the diagnosis and treatment of NB. Detection of these proteins in serum of children with NB vs controls (using 2-dimensional polyacrylamide gel electrophoresis and mass spectrometry techniques) is currently in progress.     

Murine neuroblastoma attenuates dendritic cell cysteine cysteine receptor 7 (CCR7) expression

Background/Purpose

Dendritic cell (DC) migration from tumors to T-cell priming sites is critical in developing antitumor cytotoxicity. Cysteine cysteine receptor 7 (CCR7), a promigratory chemokine receptor, regulates DC recruitment to secondary lymphoid organs. Tumors may inhibit CCR7 expression to evade immunodetection. Previous work implicates impaired DC migration as a critical defect in immunity to neuroblastoma (NB). However, the mechanism has yet to be defined. We hypothesize that NB abrogates DC CCR7 expression and signaling, leading to decreased antitumor immunity.

Methods

A/J mice (N = 36) were injected with saline (control) or murine NB (TBJ) and bone marrow-derived DC were isolated at 7, 14, and 28 days. CCR7 expression was analyzed by polymerase chain reaction, Western blot, and flow cytometry. Cytometry data were analyzed using the paired Student's t test.

Results

Dendritic cells isolated from mice with NB had a 60% increase in CCR7 protein expression by flow cytometry compared with control mice at day 7. However, there was a 43% downregulation of CCR7 expression by DC from tumor-bearing mice compared with controls 2 weeks postinoculation (P < .005). These observations were confirmed by polymerase chain reaction and Western blot analysis.

Conclusion

Neuroblastoma initially upregulates CCR7 expression by DC. However, with tumor progression, this chemokine is downregulated, likely leading to impaired DC migration. Immunotherapeutic strategies to bypass or augment CCR7-dependent DC trafficking may improve survival for patients with aggressive disease.     

Neuroblastoma-induced inhibition of dendritic cell IL-12 production via abrogation of CD40 expression

Background/Purpose

CD40 expression by dendritic cells (DCs) critically regulates their maturation/antitumor activity. CD40-CD40 ligand (CD40L) signaling stimulates DC-mediated IL-12 production/cytotoxicity. Recent studies suggest that neuroblastoma (NB)-derived gangliosides impair DC maturation, IL-12 secretion, and NK/T-cell activity. Neuroblastoma ganglioside-mediated abrogation of CD40 expression by DC and tumor-induced tolerance has not been studied. The purpose of this study is to determine if NB inhibits DC IL-12 production via CD40. The contributory role of the NB-derived ganglioside G_M3 in this process is also examined.

Methods

Dendritic cells were generated from bone marrow of mice injected with saline (control) or murine NB. Control DCs were matured with or without G_M3. Dendritic cells were cocultured with NB cells treated with or without a ganglioside synthesis inhibitor. Dendritic cell groups were analyzed for maturation/costimulatory markers. Control and tumor-derived DC were stimulated with CD40L or Staphylococcus aureus and studied for IL-12 expression.

Results

CD40 expression on DC generated from NB bearing mice decreased by 64% (P < .001). G_M3 down-regulated DC maturation and CD40 expression. Only CD40-dependent IL-12 production was abrogated (60%, P < .01) in DC derived from NB-bearing mice. Dendritic cell capacity to synthesize IL-12 remained intact.

Conclusions

Neuroblastoma-induced inhibition of DC function may result from ganglioside-mediated CD40 signaling deficiency. Strategies to bypass/augment CD40-CD40L signaling may improve current NB immunotherapies.     

Tumor necrosis factor-related apoptosis-inducing ligand is a marker of kidney function and inflammation in heart and kidney transplant recipients

Background

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) was originally identified as the third member of the TNF superfamily to induce apoptosis. TRAIL is normally expressed in many human tissues including kidney. Circulating soluble TRAIL is a negative marker for inflammation and is inversely associated with the mortality risk in chronic kidney disease patients. One increasingly prevalent complication in heart transplant recipients appears to be chronic kidney disease.

Materials and Methods

The aim of the study was to assess TRAIL concentration in 136 heart transplant recipients and 80 prevalent kidney allograft recipients in relation to kidney function. Complete blood count, urea, serum lipids, fasting glucose, creatinine, NT-proBNP were studied. Soluble TRAIL, hsCR P, interleukin-6 (IL-6), von willebrand factor (vWF) were assayed using commercially available kits.

Results

Heart transplant recipients had significantly higher serum creatinine, urea, cholesterol, triglycerides, fasting glucose, white blood cell count, serum TRAIL and lower estimated glomerular filtration rate than the control group. Similar results were obtained for kidney allograft recipients. Serum TRAIL levels fell, together with decline in glomerular filtration rate in heart transplant patients. Serum TRAIL was related to age, kidney function, erythrocyte count, hemoglobin, NT-proBNP, New York Heart Association class, presence of diabetes, high-density lipoprotein (HDL), IL-6, and ejection fraction. Age and HDL turn out to be predictors of TRAIL in heart transplant recipients. In kidney transplant recipients, TRAIL was related, in univariate analysis, to age, NT-proBNP, time after transplantation, kidney function, and vWF. In multiple regression analysis, predictors of TRAIL were vWF and time after transplantation.

Conclusion

TRAIL may represent a surrogate marker of endothelial dysfunction and atherosclerosis as these processes are accelerated in heart and kidney dysfunction.     

Glutamine induces heat-shock protein-70 and glutathione expression and attenuates ischemic damage in rat islets

Background

The transplantation of isolated islets is believed to be an attractive approach for cure of diabetes mellitus. Heat-shock protein (HSP70), which plays a vital role in cellular protection, has been detected in various tissues subjected to stress. Glutamine (GLN) is an important cellular fuel and an essential precursor for the antioxidant glutathione (GSH). It is believed to enhance cellular survival against a variety of stressful stimuli through HSP70. Thus, we performed this study to examine the hypothesis that preoperative GLN administration induces HSP70 and GSH expression before islet transplantation attenuating ischemic damage to rat islets.

Methods

Adult male Sprague-Dawley (SD) rats were randomly divided into two groups according to the administration of GLN after islet isolation. Group A served as the controls, receiving no GLN. Group B islet cells were cultured with L-GLN (10 mmol/L) supplementation for 24 hours. The GSH levels were measured in islet cells. Both HSP70 and proteins related to apoptosis were analyzed in islet cells by Western blots. Isolated rat islets were cultured with interleukin (IL)-1β. Nitrite production was measured using the Griess reagent.

Results

The GSH levels were significantly elevated in the glutamine-treated group. HSP70 expression in islets treated with GLN was markedly stronger compared with the control group. The basal Bcl-2 expression was markedly increased by GLN treatment. The GLN-treated group showed attenuated IL-1β-induced injury in association with NO production.

Conclusion

These results suggested that preoperative GLN administration induced HSP70 and GSH expressions before islet transplantation, thus attenuating IL-1β-induced injury in association with NO production and apoptosis, which might be potential tool to mitigate the ischemic damage to islet cells and the early inflammation at the site of implantation through a self-protective mechanism.     

Brain lipid-binding protein: a marker of differentiation in neuroblastic tumors

Purpose

Neuroblastoma (NB), ganglioneuroblastoma (GNB), and ganglioneuroma (GN) are neuroblastic tumours (NT) of sympathetic nervous system origin. Brain lipid-binding protein (BLBP) has potential morphogenic activity during nervous system development but has not been studied in these tumours. We analyzed the expression of BLBP in NT according to histological subtypes and extent of differentiation.

Methods

Thirty cases of NT (10 each of NB, intermixed GNB, and GN) were identified from the histopathology archive of a single center. Tissue sections were obtained from representative paraffin blocks and immunohistochemistry for BLBP performed.

Results

Brain lipid-binding protein was not expressed in any NB case. In all cases of GN, BLBP was strongly expressed in the cytoplasm of mature ganglion cells but negative in Schwannian stroma. In the intermixed GNB, there was similar strong BLBP immunoreactivity in the cytoplasm of fully differentiated and differentiating ganglion cells but no BLBP expression in immature neuroblasts.

Conclusion

Brain lipid-binding protein is strongly expressed in mature and maturing ganglion cells in NT (GN and GNB), whereas it is absent in poorly differentiated neuroblasts of GNB and NB. Cytoplasmic expression of BLBP in NT increases as the cells undergo neural differentiation and is therefore associated with the extent of tumour differentiation and favorable histology.     

Adeno-associated virus vector-mediated delivery of pigment epithelium-derived factor restricts neuroblastoma angiogenesis and growth

Purpose

The purpose of this study was to evaluate the ability of adeno-associated virus (AAV) vector-mediated delivery of pigment epithelium-derived factor (PEDF) to inhibit neuroblastoma (NB) xenograft growth. Pigment epithelium-derived factor was chosen for this study because, in addition to being a potent inhibitor of angiogenesis, it is capable of inducing neuronal differentiation.

Methods

Cohorts of mice received either recombinant AAV encoding human PEDF (rAAV-hPEDF) at a range of doses or control vector via tail vein. Subsequent hPEDF expression was measured by enzyme-linked immunoassay. After 6 weeks, the mice were given human NB cells by retroperitoneal injection and then killed 5 weeks later. Tumor weight, microvessel density, tumor differentiation, apoptosis, and levels of intratumoral vascular endothelial growth factor (VEGF) expression were determined at that time. In subsequent cohorts of mice, AAV-mediated murine PEDF expression was tested against both human NB xenografts and murine tumors.

Results

In a series of in vitro studies, PEDF was shown to inhibit endothelial cell activation and to stimulate differentiation of NB cell lines. After tail vein injection of rAAV-hPEDF, stable transgene expression was generated and correlated with levels of vector administration. Human NB xenograft growth was restricted by hPEDF in a dose-dependent fashion. Intratumoral VEGF expression and microvessel density were decreased, and tumor cell apoptosis was increased in PEDF-treated mice.

Conclusions

Treatment with PEDF had a significant impact on NB growth in mice when delivered continuously using a gene therapy-mediated approach. The activity of PEDF appears to be mediated in part by inhibition of tumor-induced angiogenesis through down-regulation of tumor-elaborated VEGF, with subsequent intratumoral apoptosis. Furthermore, hPEDF was able to induce NB differentiation in vitro and in vivo. In addition, antitumor efficacy was seen when mouse PEDF was used to treat syngeneic murine tumors. In our murine models, gene therapy-mediated delivery of PEDF appears promising for the treatment of neuroblastoma.     

Perturbation of Fgf10 signal pathway in mouse embryonic palate by dexamethasone and vitamin B12 in vivo

Background/Purpose

The Fgf10 signaling pathway plays an important role in early stages of mouse embryonic palatal development, which is associated with cell proliferation and differentiation. The objective of this study was to assess whether dexamethasone and vitamin B₁₂ affected the Fgf10 signal pathway of mouse embryonic palate.

Materials and Methods

Immunohistochemical studies were performed for expression of Fgf10, Fgfr2b, and sonic hedgehog and for cell proliferation and apoptosis of mouse embryonic palate.

Results

The expression of Fgf10, Fgfr2b, and sonic hedgehog was changed in mouse embryonic palate after dexamethasone and vitamin B₁₂ treatment, resulting in reduced and restored proliferation of mesenchymal cells.

Conclusions

Dexamethasone and vitamin B₁₂ affected the Fgf10 signaling pathway and cell proliferation of mouse embryonic palate. Cell apoptosis was not altered after dexamethasone and vitamin B₁₂ exposure.     

Effects of bone marrow stromal cells and umbilical cord blood-derived stromal cells on daunorubicin-resistant residual Jurkat cells

Objective

To observe the effects of the hematopoietic inductive microenvironment (HIM) simulated by stromal cells of different origins on daunorubicin-resistant residual Jurkat cells (Jurkat/DNR cells).

Methods

Jurkat/DNR cells were cultured and identified. Human umbilical cord blood-derived stromal cells (UCBDSCs) and normal human bone marrow stromal cells (BMSCs) were isolated and cocultured with Jurkat/DNR cells. Jurkat/DNR cells were collected after 14 days of coculture and analyzed with regard to cell proliferation and differentiation abilities, apoptosis, drug sensitivity, and MRD1 multidrug resistance gene mRNA expression.

Results

UCBDSC-simulated HIM suppressed proliferation and promoted apoptosis, differentiation, and drug sensitivity of Jurkat/DNR cells more significantly than BMSC-simulated HIM.

Conclusions

Both BMSCs and UCBDSCs reconstruct the leukemic HIM and reverse drug resistance in Jurkat/DNR cells. UCBDSCs reconstruct the leukemic HIM and reverse drug resistance more significantly than BMSCs.