[Retracted] siRNA­mediated inhibition of endogenous brain­derived neurotrophic factor gene modulates the biological behavior of HeLa cells.

Subsequently to the publication of the above article and a Corrigendum that was published to indicate corrections made to Fig. 7 (DOI: 10.3892/or.2021.7922; published online on January 5, 2021), a concerned reader drew the Editor's attention to the fact that, comparing between a pair of panels in the Figure, there was an overlapping section of data; moreover, this overlapping section contained apparent anomalies that could not be easily accounted for through a straightforward re­use of one of the data panels. The authors conceded that there was partial duplication between the images shown in Fig. 7B and F, although they were unable to access the related raw data as the experiments had been performed almost 10 years ago. Secondly, the authors informed the Editor that the corresponding author did not know he was on the author list at the time of submission. Although the authors' were granted permission to publish the Corrigendum, the Editor now considers that the paper should be retracted on account of the uncertainties in the presented revised data and the authors' admission concerning the corresponding author. Therefore, this paper has been retracted from the Journal. The authors are in agreement with the decision to retract the article. The Editor apologizes for any inconvenience caused. [Oncology Reports 37: 2751­2760, 2017; DOI: 10.3892/or.2017.5569].

[Corrigendum] siRNA-mediated inhibition of endogenous brain­derived neurotrophic factor gene modulates the biological behavior of HeLa cells.

Following the publication of this article, an interested reader drew to the authors' attention that, in Fig. 7 on p. 2757, sections of the data panels in Fig. 7A and B, showing the results of the non­transfected HeLa cell (Pnon group) and pGenesil­1­transfected HeLa cell (P0 group) experiments respectively, were strikingly similar. Both the Pnon and the P0 groups were control groups; upon re­examining their original data, the authors have realized that, when uploading the images, the data shown in Fig. 7B for the pGenesil­1­transfected HeLa cells (P0 group) were selected incorrectly. The authors were able to locate the data that were intended to have been shown in Fig. 7B; moreover, the text describing the number of migrated cells in the Results section also requires a correction. In the 'Downregulation of BDNF expression suppresses the migratory and invasive capabilities of HeLa cells' subsection, the text on lines 9­11 of this paragraph should be changed to the following (changed text is highlighted in bold): 'Migrated cells/field in the PBDNF1 group (37±17) were significantly less than those in the Pnon (105±31) and P0 (86±27) groups'. Likewise, the same correction to the text has been made to the Figure legend, as shown opposite. The revised version of Fig. 7, showing the correct data for Fig. 7B, is shown opposite. The authors are grateful to the Editor of Oncology Reports for allowing them the opportunity to publish this Corrigendum, and all of the authors agree to the publication of this Corrigendum. The authors sincerely apologize for this mistake, and regret any inconvenience this mistake has caused. [the original article was published on Oncology Reports 37: 2751-2760, 2017; DOI: 10.3892/or.2017.5569].

Efficacy and safety of bortezomib maintenance in patients with newly diagnosed multiple myeloma: a meta-analysis.

Multiple myeloma (MM) is a B-cell neoplasm with a high incidence of relapse. Bortezomib has been extensively studied for the maintenance treatment of MM. Here, we carried out a meta-analysis to determine the efficacy and safety of maintenance therapy with bortezomib. We searched for clinical trials in PubMed (Medline), Embase (OVID), and the Cochrane Library. Two randomized controlled trials (RCTs) enrolling a total of 1338 patients were included. Bortezomib maintenance statistically significantly improved both progression-free survival (PFS) (hazard ratio (HR) 0.67, 95% confidence interval (CI) = 0.51 to 0.87, P=0.003) and overall survival (OS) (HR = 0.75 therapy, 95% CI = 0.63 to 0.89, P=0.001) more than did non-bortezomib maintenance therapy. Our analysis revealed higher incidence of neutropenia (risks ratios (RR) = 1.39; 95% CI = 1.08 to 1.79), peripheral neuropathy (PN) (RR = 2.23; 95% CI = 1.38 to 3.61, P=0.001), and cardiologic events (RR = 1.91; 95% CI = 1.12 to 3.28, P=0.02) in patients with bortezomib maintenance therapy. Our meta-analysis demonstrates OS and PFS benefits of bortezomib maintenance therapy in patients with newly diagnosed MM. However, the therapy is associated with increased risk of adverse events. Additionally, more RCTs are needed for better understanding and determination of optimal bortezomib maintenance therapy in MM.

siRNA-mediated inhibition of endogenous brain­derived neurotrophic factor gene modulates the biological behavior of HeLa cells.

Brain-derived neurotrophic factor (BDNF) is expressed in a number of neural and non-neuronal tumors. The present study investigated the effect of endogenous BDNF on the biological behavior of cervix cancer cells using small interfering RNA (siRNA). HeLa, a cervix cancer cell line with high expression of BDNF, was used as a living model to screen out the effective sequences of short hairpin RNA of the BDNF gene, and the effects of RNA interference on proliferation, apoptosis, migration and invasion of these cells were evaluated. Among the 4 siRNAs examined, siRNA1 caused a 99% reduction in the relative BDNF mRNA level, while a 58% decrease in the relative BDNF protein level (p<0.01) was noted, and thus this siRNA was selected as the most efficient for use in the present study. In subsequent experiments, MTT assay revealed that BDNF silencing caused marked inhibition of HeLa cell proliferation while Hoechst 33258 staining assay demonstrated apoptosis-related changes in cell morphology. Downregulation of BDNF expression induced cell cycle arrest in the G1 phase as shown by flow cytometry. As indicated by Transwell migration and invasion assays, downregulation of BDNF expression suppressed the migratory and invasive capabilities of the HeLa cells. Together, our data revealed that BDNF modulates the proliferation, apoptosis, migratory and invasive capabilities of HeLa cells. BDNF siRNA may represent a novel therapy or drug target for preventing the tumorigenesis of cervical cancer.

Targeting the miR-221-222/PUMA/BAK/BAX Pathway Abrogates Dexamethasone Resistance in Multiple Myeloma.

Despite recent therapeutic advances that have doubled the median survival time of patients with multiple myeloma, intratumor genetic heterogeneity contributes to disease progression and emergence of drug resistance. miRNAs are noncoding small RNAs that play important roles in the regulation of gene expression and have been implicated in cancer progression and drug resistance. We investigated the role of the miR-221-222 family in dexamethasone-induced drug resistance in multiple myeloma using the isogenic cell lines MM1R and MM1S, which represent models of resistance and sensitivity, respectively. Analysis of array comparative genome hybridization data revealed gain of chromosome X regions at band p11.3, wherein the miR-221-222 resides, in resistant MM1R cells but not in sensitive MM1S cells. DNA copy number gains in MM1R cells were associated with increased miR-221-222 expression and downregulation of p53-upregulated modulator of apoptosis (PUMA) as a likely proapoptotic target. We confirmed PUMA mRNA as a direct target of miR-221-222 in MM1S and MM1R cells by both gain-of-function and loss-of-function studies. In addition, miR-221-222 treatment rendered MM1S cells resistant to dexamethasone, whereas anti-miR-221-222 partially restored the dexamethasone sensitivity of MM1R cells. These studies have uncovered a role for miR-221-222 in multiple myeloma drug resistance and suggest a potential therapeutic role for inhibitors of miR-221-222 binding to PUMA mRNA as a means of overcoming dexamethasone resistance in patients. The clinical utility of this approach is predicated on the ability of antisense miR-221-222 to increase survival while reducing tumor burden and is strongly supported by the metastatic propensity of MM1R cells in preclinical mouse xenograft models of multiple myeloma. Moreover, our observation of increased levels of miR-221-222 with decreased PUMA expression in multiple myeloma cells from patients at relapse versus untreated controls suggests an even broader role for miR-221-222 in drug resistance and provides a rationale for the targeting of miR-221-222 as a means of improving patient outcomes.

miR-30-5p functions as a tumor suppressor and novel therapeutic tool by targeting the oncogenic Wnt/ß-catenin/BCL9 pathway.

Wnt/ß-catenin signaling underlies the pathogenesis of a broad range of human cancers, including the deadly plasma cell cancer multiple myeloma. In this study, we report that downregulation of the tumor suppressor microRNA miR-30-5p is a frequent pathogenetic event in multiple myeloma. Evidence was developed that miR-30-5p downregulation occurs as a result of interaction between multiple myeloma cells and bone marrow stromal cells, which in turn enhances expression of BCL9, a transcriptional coactivator of the Wnt signaling pathway known to promote multiple myeloma cell proliferation, survival, migration, drug resistance, and formation of multiple myeloma cancer stem cells. The potential for clinical translation of strategies to re-express miR-30-5p as a therapeutic approach was further encouraged by the capacity of miR-30c and miR-30 mix to reduce tumor burden and metastatic potential in vivo in three murine xenograft models of human multiple myeloma without adversely affecting associated bone disease. Together, our findings offer a preclinical rationale to explore miR-30-5p delivery as an effective therapeutic strategy to eradicate multiple myeloma cells in vivo.

Role of brain-derived neurotrophic factor in bone marrow angiogenesis in multiple myeloma.

This study examined the expression of brain-derived neurotrophic factor (BDNF) in multiple myeloma (MM) and its role in bone marrow angiogenesis. The peripheral blood plasma was harvested from 71 MM patients and 63 patients without hematological malignancy. The BDNF level in the blood plasma was determined by ELISA. Human bone marrow endothelial cells (HBMECs) were cultured. The mRNA and protein expression levels of the BDNF receptor TrkB in HBMECs were detected by using RT-PCR and flow cytometry, respectively. The viability of HBMECs treated with recombinant human (rh) BDNF or not was measured by using MTT assay. The migration of HBMECs in the presence of rhBDNF or not was determined by modified Boyden chamber assay. In vitro tube formation assay was used to assess the effect of rhBDNF on HBMECs differentiation. The results of ELISA revealed that the BDNF level was significantly higher in peripheral blood plasma of MM patients than in that of control patients (4.39±0.67 vs. 1.96±0.39 ng/mL, P<0.05). The BDNF receptor TrkB was expressed in HBMECs at mRNA and protein level. MTT assay manifested that rhBDNF could significantly concentration-dependently promote the HBMECs proliferation. The number of HBMECs treated with 160 ng/mL rhBDNF for 48 h was 1.57±0.10 folds higher than that in control group (P<0.05). Moreover, rhBDNF could enhance HBMECs migration in a concentration-dependent manner and the maximal migration was reached in the presence of 100 ng/mL rhBDNF. The migration indexes were 1.40±0.11, 1.64±0.16, 2.06±0.25 and 2.18±0.21 in 25, 50, 100 ng/mL rhBDNF groups and 25 ng/mL rhVEGF group, respectively. In vitro tube formation assay demonstrated that the area of the formed tubular structure was increased with the rhBDNF concentration. In control group, there was no formation of intact tubular structure and the HBMECs on the matrigel were irregularly dispersed. HBMECs treated with 100 ng/mL rhBDNF could form intact tubular structure and the area and the diameter of tubes were significantly greater than those in control group (P<0.05). There was no significant difference in the formed tubular area between 25 ng/mL VEGF group and 100 ng/mL rhBDNF group. It was concluded that BDNF plays an important role in myeloma cell-induced angiogenesis, and it may become a new target of anti-angiogenesis treatment for MM.

Gene silencing of the BDNF/TrkB axis in multiple myeloma blocks bone destruction and tumor burden in vitro and in vivo.

Osteolytic bone diseases are a prominent feature of multiple myeloma (MM), resulting from aberrant osteoclastic bone resorption that is uncoupled from osteoblastic bone formation. Myeloma stimulates osteoclastogenesis, which is largely dependent on an increase in receptor activator of NF-κB ligand (RANKL) and a decrease in osteoprotegerin (OPG) within the bone marrow milieu. Recently, brain-derived neurotrophic factor (BDNF) was identified as a MM-derived factor that correlates with increased RANKL levels and contributes to osteolytic bone destruction in myeloma patients. Because tyrosine receptor kinase B (TrkB), the receptor of BDNF, is abundantly expressed in osteoblasts, we sought to evaluate the role of BDNF/TrkB in myeloma-osteoblast interactions and the effect of this pathway on the RANKL/OPG ratio and osteoclastogenesis. Coculture systems constructed with noncontact transwells revealed that, in vitro, MM-derived BDNF increased RANKL and decreased OPG production in osteoblasts in a time- and dose-dependent manner. These effects were completely abolished by a specific small interfering RNA for TrkB. BDNF regulates RANKL/OPG expression in osteoblasts through the TrkB/ERK pathway. To investigate the biological effects of BDNF on myeloma in vivo, a SCID-RPMI8226 mice model was constructed using lentiviral short hairpin RNA-transfected RPMI8226 cells. In this system, stable knockdown of BDNF in MM cells significantly restored the RANKL/OPG homostasis, inhibited osteolytic bone destruction and reduced angiogenesis and tumor burden. Our studies provide further support for the potential osteoclastogenic effects of BDNF, which mediates stroma-myeloma interactions to disrupt the balance of RANKL/OPG expression, ultimately increasing osteoclastogenesis in MM.

miR-15a and miR-16 affect the angiogenesis of multiple myeloma by targeting VEGF.

Deregulated microRNAs (miRNAs) and their roles in cancer development have attracted much attention. Two miRNAs, miR-15a and miR-16, which act as putative tumor suppressor by targeting the oncogene BCL2, have been implicated in cell cycle, apoptosis and proliferation. In this study, we investigated the possible role of miR-15a/16 in the angiogenesis of multiple myeloma (MM). Using a stem-loop quantitative reverse transcription-PCR, we analyzed miR-15a/16 expressions in bone marrow samples from newly diagnosed MM patients and a panel of MM cell lines. miRNA transfection, western blotting analysis and assay of luciferase activity were used to examine whether vascular endothelial growth factor (VEGF) is the target of miR-15a/16. The functional roles of miR-15a/16 on tumorigenesis and angiogenesis were examined by in vitro angiogenesis models and in vivo tumor xenograft model. We showed that miR-15a and miR-16 were significantly underexpressed in primary MM cells as well as in MM cell lines. The aberrant expression of miR-15a/16 was detected especially in advanced stage MM. In human MM cell lines and normal plasma cells, expression of miR-15a/16 inversely correlated with the expression of VEGF-A. Western blotting combined with the luciferase reporter assay demonstrated that VEGF-A was a direct target of miR-15a/16. Ectopic overexpression of miR-15a/16 led to decreased pro-angiogenic activity of MM cells. Finally, infection of lentivirus-miR-15a or lentivirus-miR-16 resulted in significant inhibition of tumor growth and angiogenesis in nude mice. This study suggest that miR-15a/16 could play a role in the tumorigenesis of MM at least in part by modulation of angiogenesis through targeting VEGF-A.

Inhibition of BDNF in multiple myeloma blocks osteoclastogenesis via down-regulated stroma-derived RANKL expression both in vitro and in vivo.

Brain-derived neurotrophic factor (BDNF) was recently identified as a factor produced by multiple myeloma (MM) cells, which may contribute to bone resorption and disease progression in MM, though the molecular mechanism of this process is not well understood. The purpose of this study was to test the effect of BDNF on bone disease and growth of MM cells both in vitro and in vivo. Co- and triple-culture systems were implemented. The in vitro results demonstrate that BDNF augmented receptor activator of nuclear factor kappa B ligand (RANKL) expression in human bone marrow stromal cells, thus contributing to osteoclast formation. To further clarify the effect of BDNF on myeloma bone disease in vivo, ARH-77 cells were stably transfected with an antisense construct to BDNF (AS-ARH) or empty vector (EV-ARH) to test their capacity to induce MM bone disease in SCID-rab mice. Mice treated with AS-ARH cells were preserved, exhibited no radiologically identifiable lytic lesions and, unlike the controls treated with EV-ARH cells, lived longer and showed reduced tumor burden. Consistently, bones harboring AS-ARH cells showed marked reductions of RANKL expression and osteoclast density compared to the controls harboring EV-ARH cells. These results provide further support for the potential osteoclastogenic effects of BDNF, which may mediate stromal-MM cell interactions to upregulate RANKL secretion, in myeloma bone diseases.

Brain-derived neurotrophic factor is a potential osteoclast stimulating factor in multiple myeloma.

Multiple myeloma (MM) is characterized by accumulation of monoclonal plasma cells in the bone marrow and progression of lytic bone lesions. The mechanisms of enhanced bone resorption in patients with myeloma are not fully defined. We have previously identified the role of brain-derived neurotrophic factor (BDNF) in proliferation and migration of MM cells. In our study, we investigated whether BDNF was possibly involved in MM cell-induced osteolysis. We showed that BDNF was elevated in MM patients and the bone marrow plasma levels of BDNF positively correlated with extent of bone disease. In osteoclast formation assay, bone marrow plasma from patients with MM increased osteoclast formation and the effect was significantly blocked by neutralizing antibody to BDNF, suggesting a critical role for BDNF in osteoclast activation. Furthermore, the direct effects of recombinant BDNF on osteoclast formation and bone resorption support the potential role of BDNF in the MM bone disease. BDNF receptor TrkB was expressed by human osteoclast precursors and a Trk inhibitor K252a markedly inhibited osteoclast formation stimulated with BDNF, demonstrating that BDNF used TrkB for its effects on osteoclast. Finally, bone marrow plasma BDNF level positively correlated with macrophage inflammatory protein-1α and receptor activator of nuclear factor-κB ligand, two major osteoclast stimulatory factors in MM. These results support an important role for BDNF in the development of myeloma bone disease.

Brain-derived neurotrophic factor induces proliferation, migration, and VEGF secretion in human multiple myeloma cells via activation of MEK-ERK and PI3K/AKT signaling.

This study investigated the signaling pathways involved in the different biological effects of brain-derived neurotrophic factor (BDNF) in multiple myeloma (MM). The effects of BDNF on proliferation of MM cell lines and primary myeloma cells were examined by [(3)H]thymidine incorporation assay. The effects of BDNF on MM cells migration were studied by transwell migration assay. Stimulation by BDNF of vascular endothelial growth factor (VEGF) production was analyzed by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay. The signal-transduction pathways that are activated in response to BDNF were determined by Western blots. VEGF is induced by BDNF in a dose-dependent manner in MM cells. Stimulation of MM cells with BDNF led to the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt and the MEK-extracellular signal-regulated protein kinase pathways. Using specific signal-transduction inhibitors, we demonstrated that MEK is required for BDNF-induced proliferation, whereas activation of PI3K is required for BDNF-stimulated migration and VEGF production. BDNF affects different cell signaling pathways mediating growth, migration, and VEGF secretion in MM cells. Our observations provided the framework for novel therapeutic strategies targeting BDNF signaling cascades in MM.

Lentiviral shRNA silencing of BDNF inhibits in vivo multiple myeloma growth and angiogenesis via down-regulated stroma-derived VEGF expression in the bone marrow milieu.

Bone marrow (BM) neovascularization and vascular endothelial growth factor (VEGF) expression in multiple myeloma (MM) correlate with disease progression. Brain derived neurotrophic factor (BDNF) is highly expressed by malignant plasma cells isolated from the majority of MM patients. Recently, BDNF was identified as a potential proangiogenic factor for the promotion of endothelial cell survival, induction of neoangiogenesis in ischemic tissues, and increase of VEGF expression in neuroblastoma. Since tropomyosin receptor kinase B (TrkB), the receptor of BDNF, is expressed by stromal cells within the BM milieu, here we sought to evaluate the involvement of BDNF/TrkB in myeloma-marrow stroma interaction and its effects on BM angiogenesis. TrkB was abundantly expressed by bone marrow stromal cells (BMSCs) isolated from healthy donors. Stimulation of BMSCs with BDNF induced a time- and dose- dependent increase in VEGF secretion, which was completely abolished by K252alpha, an inhibitor of TrkB. BDNF triggered activation of signal transducer and activator of transcription 3 (STAT3) and activator protein-1 (AP-1), whereas STAT3 was involved in mediating VEGF expression. We further delineated the biological significance of BDNF in MM by using lentiviral short-interfering RNA (shRNA). When myeloma cells were cocultured with BMSCs in a noncontact Transwell system, VEGF levels in supernatants were significantly decreased when BDNF expression was knocked down. Furthermore, silencing of BDNF expression significantly inhibited xenograft tumor growth and angiogenesis, and prolonged survival in mouse model. Our studies demonstrate that BDNF, as a potential stimulator of angiogenesis, contributes to MM tumorgenesis; it mediates stromal-MM cell interactions via selective activation of specific receptor TrkB and downstream signal transducer STAT3, regulating VEGF secretion.

Successful treatment of myeloid neoplasms associated with PDGFRA rearrangement with imatinib mesylate.

Hypereosinophilic syndromes (HES) constitute a rare and heterogeneous group of disorders, defined as persistent and marked blood eosinophilia associated with evidence of eosinophil-induced organ damage. Cardiac dysfunction is the most frequent result of end-organ damage and is the major cause of morbidity and mortality among patients with HES. Despite patients with FIP1-like-1-platelet-derived growth factor alpha (FIP1L1-PDGFRA) associated HES (myeloid neoplasms associated with PDGFRA rearrangement) have been shown to respond to low-dose imatinib with a complete and durable hematological and cytogenetic remission, influences of imatinib on clinical manifestations related to hypereosinophilia heart involvement are variable. Here we describe the case of a young male patient with severe heart involvement who had a prompt, clinical and hematological complete remission following administration of imatinib. However, as endomyocardial fibrosis and related loss of function are deteriorated after initiation of imatinib therapy, valvular replacement and tricuspid annuloplasty had to perform to restore his heart function. Our finding concurs with recent reports that severe heart involvement was irreversible with imatinib treatment.

[Effect of RNA interference targeting brain-derived neurotrophic factor gene on HeLa cell proliferation and apoptosis].

OBJECTIVE: To screen effective sequences of short hairpin RNA on brain-derived neurotrophic factor (BDNF) gene and the effect of RNA interference on the proliferation and apoptosis of HeLa cells, a cervix carcinoma cell line with high expression of BDNF. METHODS: Two recombinant eukaryotic human-BDNF siRNA expression vectors were designed and constructed. Sequences were confirmed by restrictive endonuclease digestion and DNA sequencing. The empty vector pGenesil-1 and two recombinant plasmids, pGenesil-shRNA-BDNF1 and pGenesil-shRNA-BDNF2, were transfected into HeLa cells using Lipofectamine 2000 (groups: P(0), P(1) and P(2), respectively). The mRNA and protein levels of BDNF in HeLa cells were detected by RT-PCR and Western blot, respectively. The cellular proliferation rates were determined by MTT assay and the apoptotic rates were measured by flow cytometry and Hoechest 33258. RESULTS: The recombinant eukaryotic BDNF siRNA expression vectors were successfully constructed. The expression of mRNA and protein of BDNF in P(1) group were significantly decreased, comparing with non-transfected group, P(0) and P(2) groups (F = 48.19, P < 0.01). P(2) group failed to meet the expected results (P > 0.05). In addition, the proliferation activity was reduced in P(1) group and the peak point of proliferation curve was prolonged. Moreover, the early cell apoptotic rates were statistically increased in P(1)[(53.4 +/- 4.2)%] VS. non-transfected [(0.8 +/- 0.4)%], P(0) [(5.1 +/- 1.8)%] and P(2)[(7.9 +/- 2.4)%] groups (F = 269.77, P < 0.01). CONCLUSION: HeLa cells express a high level of BDNF. BDNF gene silencing by RNA interference increases the apoptosis of HeLa cells and inhibits cell proliferation, offering a possible target for efficient tumor therapy.

[Study of brain-derived neurotrophic factor activating TrkB signaling cascades in the pathogenesis of multiple myeloma].

OBJECTIVE: To explore the significance of abnormal expression of brain-derived neurotrophic factor (BDNF)/TrkB in the development and evolution of multiple myeloma (MM) and the involved signaling pathways. METHODS: The effect of BDNF on the cell viability of human myeloma cell line (HMCL) (RPMI8226, U266, KM3) was determined by trypan blue dye-exclusion. MTT assay was used to evaluate the cytotoxicity of tested chemotherapeutic agents. The effect of BDNF on the phosphorylation of TrkB was determined by Western blot. A human myeloma xenograft animal model was used to evaluate the effects of BDNF on tumor growth and survival time. RESULTS: BDNF at 50 microg/L triggered significant increase in cell viability of HMCL. BDNF protected KM3 cells from melphalan and vincristine. The viability of KM3 cells exposed to varying concentrations of melphalan with and without 50 microg/L BDNF showed that BDNF induced almost a 2-fold and a 3-fold increase in melphalan and vincristine toxicity respectively. BDNF treatment increased MM cell growth in xenografted MM model (3240.9 mm3 vs 1032.7 mm3 ) (P <0.05). Intratumoral injection of BDNF also significantly reduced survival time (13 d vs 21 d) (P <0.05). The phosphorylated TrkB level was increased significantly after treated by exogenous BDNF. BDNF-triggered migration in RPMI8226 cells was completely abrogated by a Trk tyrosine kinase inhibitor K252a. CONCLUSION: BDNF can activate TrkB signaling cascades resulting in MM cells growth, migration, and chemoprotection and appears to have a major contribution to the pathogenesis of MM.

[Brain-derived neurotrophic factor promotes the secretion of MMP-9 in human myeloma cell through modulation of nucleus factor-kappaB].

OBJECTIVE: To explore the mechanism of brain-derived neurotrophic factor (BDNF) promoting human multiple myeloma (MM) cells secreting matrix metalloproteinase-9 ( MMP-9). METHODS: Gelatin zymography of culture supernatants was performed to visualize the content of MMPs in myeloma RPMI 8226 cells stimulated by BDNF. NF-kappaB activity was determined by chemiluminescent electrophoretic mobility shift assay (EMSA). RESULTS: Treatment with 25, 50, 100 and 200 microg/L BDNF for 24 h significantly (P < 0.01) enhanced the level of MMP-9 (2.03+/-0.48, 2.99+/-0.046, 4.63+/-0.62 and 5.62+/-1.29 microg/L, respectively, vs 1.00 microg/L of the control) secreted by RPMI8226 cells in a dose-dependent manner, while that of MMP-2 was not changed significantly (P > 0.05). The BDNF-induced activation of MMP-9 was inhibited by pretreatment with pyrrolidine dithiocarbamate (PDTC), a NF-kappaB inhibitor, or K252 alpha, a specific tyrosine inhibitor of TrkB which is the receptor for BDNF. Pretreated with 1 mmol/L PDTC or 500 nmol/L K252 alpha significantly downregulated MMP-9 secreted by the 100 microg/L of BDNF stimulated RPMI 8226 cells (the optical density values were 867.52+/-101.81 and 727.98 +/-92.05, respectively, vs 1,159.01+/-233.15 of the control). The activity of NF-kappaB was enhanced by BDNF in a dose-dependent manner, and pretreatment with K252 alpha could significantly inhibit this activation at 1, 6, 12 and 24 h (P < 0.05) in a time-dependent manner. CONCLUSION: BDNF plays an important role in the angiogenesis of MM to promote the up-regulation of MMP-9, which may be induced by enhanced NF-kappaB activity in MM cells.

Antimyeloma effects of resveratrol through inhibition of angiogenesis.

BACKGROUND: In multiple myeloma (MM), bone marrow angiogenesis parallels tumour progression and correlates with disease activity. Recent studies have proved resveratrol possesses antiangiogenic activity in vitro and in vivo. In this study, we examined the effects of resveratrol on myeloma cell dependent angiogenesis and the effects of resveratrol on some important angiogenic factors of RPMI 8226 cells. METHODS: RPMI 8226 cells were cocultured with human umbilical vein endothelial cells (HUVECs) to evaluate the effects of myeloma cells on angiogenesis. The RPMI 8226 cells were treated with various concentrations of resveratrol (6.25 - 50.00 micromol/L) for different times (12 - 72 hours). Reverse transcriptase polymerase chain reaction (RT-PCR) was used to assay vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), metalloproteinases (MMP)-2 and MMP-9 mRNA. Gelatin zymography was used to analyze MMP-2 and MMP-9 activity. VEGF and bFGF proteins secreted by the cells in the medium were quantified by enzyme linked immunosorbent assay (ELISA). RESULTS: Cell proliferation, migration and differentiation of HUVECs markedly increased by coculture with RPMI 8226 cells. Resveratrol inhibited proliferation, migration and tube formation of HUVECs cocultured with myeloma cells in a dose dependent manner. Treatment of RPMI 8226 cells with resveratrol caused a decrease in MMP-2 and MMP-9 activity. Resveratrol inhibited VEGF and bFGF protein expression in a dose and time dependent manner. Furthermore, decreased levels of VEGF, bFGF, MMP-2 and MMP-9 mRNA from cells treated with various concentrations of resveratrol confirmed its antiangiogenic action at the level of gene expression. CONCLUSIONS: Resveratrol inhibits multiple myeloma angiogenesis by regulating expression and secretion of VEGF, bFGF, MMP-2 and MMP-9. Resveratrol may be a potential candidate for the treatment of multiple myeloma.