Novel mechanistic study of HDAC6 regulation of rheumatoid arthritis via CMA: exploring potential therapeutic targets.

Objective: Rheumatoid arthritis (RA) is a systemic autoimmune disease. Its pathogenesis has not yet been clarified, so it is urgent to explore therapeutic targets. Here, we clarified the role of HDAC6 in the mechanism of action of RA through mediating chaperone-mediated autophagy (CMA) to provide a clinical treatment of RA. Methods: We used rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) and collagen-induced arthritis mice (CIA mice) as models of RA and pharmacological inhibitors as well as genetic interference with adeno-associated viruses to reduce the expression of HDAC6. We explored the influence of CAY10603 on RA-FLS proliferation and inflammation, as well as the expression of proteins related to the CMA signaling pathway. CIA model was constructed using DBA/1J mice. Arthritis symptoms in CIA mice were evaluated, and the expression and localization of CMA-related proteins in mouse ankle joints were examined. Results: CAY10603 inhibited proliferation as well as the level of the molecular chaperone autophagy in RA-FLS. HDAC6 shRNA significantly reduced the clinical signs of arthritis in CIA mice, as did the expression of HDAC6 in the serum and ankle synovial tissues of CIA mice. Finally, it significantly inhibited the level of Hsc70 and LAMP-2A, which are involved in the CMA signaling pathway, in ankle joint tissues. Conclusion: Downregulation of HDAC6 may inhibit CMA and thereby ameliorate RA.

A novel single domain bispecific antibody targeting VEGF and TNF-α ameliorates rheumatoid arthritis.

Anti-TNF-α therapy fails in 30% of patients, where TNF-α may not be the key causative factor in these patients. We developed a bispecific single-domain antibody block TNF-α and VEGF (V5-3).The experiments showed that V5-3 effectively activated proliferation and migration of RA-FLS and HUVEC, tube-forming role of HUVEC, and expression of inflammatory factors in vitro. Besides, the experiments indicated that the anti-RA activity of V5-3 was superior to Anbainuo in vivo. Application of V5-3 reduced the expression of inflammatory factors, extent of synovial inflammation and angiogenesis and attenuated the severity of autoimmune arthritis in collagen-induced arthritis (CIA) mice. Mechanistically, V5-3 suppressed p65, AKT and VEGFR2 phosphorylation, as well as production of TNF-α and VEGF in joint tissues. These results demonstrated that V5-3 displayed a superior effect of anti-RA, may be a new therapy to overcome the limitations of anti-TNF-α monoclonal antibody.

[Effect of Met Knockdown on Biological Behavior of Multiple Myeloma RPMI 8226 Cells].

OBJECTIVE: To investigate the effects of down-regulating of c-Met expression to the proliferation, invasiveness and apoptosis of human multiple myeloma RPMI 8226 cells. METHODS: According to transfection the RPMI8226 cells were dividide into RPMI 8226 (untreated RPMI 8226), RPMI 8226 /shRNA-Met and RPMI8226/shRNA-control group, respectively. Protein expression level of c-Met was detected by Western blot so as to evaluate transfection condition; the proliferation of the cells was detected by MTT; apoptosis and cycle of the cells were detected by flow cytometry; effect of c-Met/shRNA on RPMI 8226 cell adhesion was detected by RPMI 8226 cell adherence to ECM (Fn and Matrigel) and ECV304 cells. Invasiveness of RPMI 8226 cell was detected by Transwell assay. RESULTS: The c-Met short hairpin RNA (shRNA) was successfully transfected into RPMI 8226 cells, and could inhibit the expression of c-Met significantly. The down-regulation of c-Met could inhibit the proliferation of RPMI 8226 cells significantly. The percentage of cells in the G0/G1 phase and apoptotic rate (sub-G1) in the RPMI 8226/shRNA-Met group were higher than those in the control group, the adhesion rate and the number of migrated RPMI 8226/shRNA-Met cells were decreased significantly as compared with control group. There were no significant differences in each indexes between RPMI 8226/shRNA-control and control group. CONCLUSION: Knockdown of c-Met can affect the proliferation, adherence, invasiveness and apoptosis of human multiple myeloma RPMI 8226 cells.

Antiproliferation activities of NK4 on multiple myeloma.

Multiple myeloma (MM) is a plasma cell malignancy. The hepatocyte growth factor (HGF) has been demonstrated to promote MM cell growth. NK4, a splice variant of HGF in which the heavy chain consists of the N-terminal domain and the four kringle domains, is a specific antagonist of HGF that competes with HGF for tyrosine-protein kinase receptor binding. The current study aimed to examine the antiproliferative activity of NK4 on human MM cells and to investigate the underlying mechanism. The results indicated that NK4 suppressed proliferation and induced apoptosis in RPMI 8226 cells. In addition, NK4 altered the expression of cell cycle and apoptosis-associated proteins in RPMI 8226, including cyclin-dependent kinase 4, cyclin D1, cyclin-dependent kinase inhibitor 1B, apoptosis regulator Bcl-2, apoptosis regulator BAX, cleaved caspase-9 and caspase-3. Furthermore, NK4 inhibited the activation of the RAC-α serine/threonine-protein kinase (Akt)/serine/threonine-protein kinase mTOR (mTOR) signaling pathway and reduced the levels of phosphorylated (p)-Akt, p-mTOR, ribosomal protein S6 kinase beta-1 and eukaryotic initiation factor 4E binding protein 1 in RPMI 8226 cells. In conclusion, NK4 inhibited the proliferation of human MM RPMI 8226 cells, which may be attributed to the induction of apoptosis and the inhibition of the Akt/mTOR signaling pathway.

NK4 inhibits the proliferation and induces apoptosis of human rheumatoid arthritis synovial cells.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by proliferation and insufficient apoptosis of synovial cells. NK4 is a hepatocyte growth factor antagonist and is implicated in cell proliferation, viability, and apoptosis of many tumour cells. This study aimed to investigate the role of NK4 in the regulation of human RA synovial cell proliferation and apoptosis. Fibroblast-like synoviocytes (FLSs) isolated from RA patients and MH7A synovial cells were subjected to MTT, flow cytometry, and Western blot analysis. We found that NK4 suppressed cell proliferation through cell cycle arrest at the G0/G1 phase and induced apoptosis in RA synovial cells. Furthermore, NK4 altered the expression of cell cycle and apoptosis-related proteins such as cyclin D1, cyclin B1, PCNA, p21, p53, Bcl-2, Bax, cleaved caspase-9, and cleaved caspase-3. Additionally, NK4 reduced the phosphorylation level of NF-κB p65 and upregulated the expression of sirt1, but did not change the levels of p38 and p-p38 in RA-FLS and MH7A cells. In conclusion, NK4 inhibits the proliferation and induces apoptosis of human RA synovial cells. NK4 is a promising therapeutic target for RA. We demonstrated that NK4 inhibited cell proliferation by inducing apoptosis and arresting cell cycle in RA-FLS and MH7A cells. The apoptotic effects of NK4 may be mediated in part by decreasing Bcl-2 protein level, increasing Bax and caspase 3 protein levels, and inhibiting NF-κB signalling in RA-FLS and MH7A cells. These findings reveal potential mechanism underlying the role of NK4 in RA synovial cells and suggest that NK4 is a promising agent for RA treatment.

[Establishment of BOR-Resistant U266 Cell Line and the Detection of Its Biological Activities].

OBJECTIVE: To establish bortezomib (BOR)-resistant human multiple myeloma U266 cell line U266/BOR and to detect its biological characteristics. METHODS: U266 cells were constantly exposed at low dose and progressively increasing dose of BOR to establish U266/BOR, the cell morphology was observed by inverted microscopy, IC50 and resistant index were determined by MTT assay, cell growth curve was drawed and the doubling time was calculated; cell cycle distribution were analyzed by flow cytometry, and RT-PCR was used to detect the mRNA expression of resistance-related genes. RESULTS: The MM U266/BOR cell line was successfully constructed and its resistance index was up to 19.8. The both cell morphologies were not different. Compared with U266 cells, the multiplication time was postponed with the increase of G0/G1 cell ratio, and S phase was reduced. The mRNA expression of PTPROt, Beclin 1 and PTEN were reduced, and the mRNA expression of c-Maf was enhanced in U266/BOR cells; as compared with U266 cells, but the MDR1 mRNA expression was not different between U266 cells and U266 BOR cells. CONCLUSION: The BOR-resistant U266 cell line has been establiseed successfully. It provides an ideal cell model for further exploration of the mechanism for BOR resistance.

[Anti-proliferation Effect of NS-398 in Combination with Bortezomib on Multiple Myeloma RPMI 8226 Cells In Vitro].

OBJECTIVE: To investigate if NS-398 could enhance the chemosensitivity of Bortezomib (BOR) on human multiple myeloma RPMI 8226 cells. METHODS: After the treatment of NS-398 combined with BOR, MTT assay was used to detect the proliferation inhibition effect on human multiply myeloma RPMI 8226 cells in vitro, Flow cytometry was used to analyze their effect of apoptosis and cell cycle; the caspase-3 activity of different treatment group was detected by using ELISA and the activity of Cox-2 was measured by using Cox-2 activity assay kit. RESULTS: The inhibitory rate of NS-398 combined with BOR was higher than that of NS-398 or BOR alone(Q>0.85). After treatment of NS-398 combined with BOR, the percentage of cells arrested in the G0/G1 phase and apoptotic rate were both higher than that of treatment with each drug alone(Q>1.15). The caspase-3 activity in cells treated with combined of NS-398 and BOR was significantly higher than that of treatment of each drug alone(Q>1.15). CONCLUSION: NS-398 combined with BOR shows a synergistic effect on the growth inhibition of RPMI 8226 cells in vitro.

[Ad-NK4 Enhances the Chemosensitivity of Human Multiple Myeloma RPMI 8226 Cells to Bortezomib].

OBJECTIVE: To investigate if Ad-NK4 can enhance the chemosensitivity of human multiple myeloma RPMI 8226 cells to bortezomib(BOR). METHODS: The cell-matrix adhesion test and PRMI 8226 cell-ECV 304 cell adhesion test were used to analyze the effect of Ad-NK4 on adhesion of RPMI 8226 cells; Western blot was used to detect the expression changes of adhesion and invasion-associated proteins MMP2, MMP3, MMP7 and VEGF; MTT assay was used to detect the effect of Ad-NK4 on proliferation of RPMI 8226 cells; the flow cytometry with PI staining was used to detect the effect of Ad-NK4 on cell apoptosis; the expression of cleaved caspase-3, BAX and BCL-2 was assayed by Western blot. RESULTS: These 2 adhesion assays indicated that Ad-NK4 significantly inhibited the adhesion of human multiple myeloma RPMI 8226 cells. In addition, Erk and JAK/STAT pathway may be involved in the process. The expression level of MMP-2, MMP-3 and VEGF were decreased in Ad-NK4 group, compared with untreated or Ad-GFP group (P<0.05). However, the expression of MMP-7 protein in Ad-NK4 group was not significantly different from untreated or Ad-GFP group (P>0.05). The inhibitory rates of the proliferation in cells treatedly Ad-NK4 combined with BOR was significantly higher than that with BOR or Ad-NK4 alone. Similarly, Western blot indicated that the level of cleaved caspase-3 and BAX in cells treated with Ad-NK4 combined with BOR was significantly higher than BOR or Ad-NK4 alone, but BCL-2 protein expression was significantly lower. Meanwhile, the ratio of BAX/BCL-2 was increased. CONCLUSION: Ad-NK4 can enhance the chemosensitivity of human multiple myeloma RPMI 8226 cells to BOR,which is associated with increasing of both BAX/BCL-2 ratio and Caspase-3 activation.

Knockdown of DEPTOR inhibits cell proliferation and increases chemosensitivity to melphalan in human multiple myeloma RPMI-8226 cells via inhibiting PI3K/AKT activity.

OBJECTIVE: The present study determined the role of DEP domain containing mTOR-interacting protein (DEPTOR) in the proliferation, apoptosis and chemosensitivity of RPMI-8226 multiple myeloma cells, using small hairpin RNA (shRNA) to knock down DEPTOR gene expression in vitro. METHODS: DEPTOR mRNA and protein levels in RPMI-8226 cells treated with DEPTOR-specific shRNA were evaluated by reverse transcription-polymerase chain reaction and Western blotting. Expression of apoptosis-associated proteins (including cleaved caspase-3 and cleaved poly-ADP ribose polymerase [PARP]) and activation of the phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homologue 1 (AKT) signalling pathway were detected by Western blotting. RESULTS: Transfection of DEPTOR-specific shRNA successfully knocked down DEPTOR gene expression in transfected RPMI-8226 cells. These transfected cells, together with control RPMI-8226 cells, were treated with 20 µmol/l melphalan for 24 h. Knockdown of DEPTOR exacerbated melphalan-induced growth inhibition and apoptosis, increased levels of cleaved caspase-3 and cleaved PARP, and reduced levels of phosphor-AKT. CONCLUSION: Downregulation of DEPTOR inhibited proliferation and increased chemosensitivity to melphalan in human multiple myeloma RPMI-8226 cells via inhibiting the PI3K/AKT pathway.

NS-398 enhances the efficacy of bortezomib against RPMI8226 human multiple myeloma cells.

Bortezomib is commonly used in treating multiple myeloma (MM). However, a number of patients develop resistance to bortezomib over time. Cox-2 is overexpressed in MM cells and contributes to apoptosis resistance and MM development. In the present study, RPMI8226 MM cells were treated with the Cox-2 inhibitor NS-398 to investigate whether it enhanced the effect of bortezomib on MM. The results showed that NS-398 and bortezomib acted synergistically to inhibit growth, arrest the cell cycle at the G1 phase and to induce the apoptosis of MM cells. NS-398 inhibited the NF-κB p65 protein levels and the expression of various NF-κB target genes, including cyclin D1, c-Myc, survivin and Bcl-2. In conclusion, NS-398 enhanced the efficacy of bortezomib against MM cells in vitro and this was associated with the inhibition of NF-κB signaling. These findings suggest that the combined use of NS-398 and bortezomib may constitute a promising novel treatment protocol for MM patients.

Knockdown of DEPTOR induces apoptosis, increases chemosensitivity to doxorubicin and suppresses autophagy in RPMI-8226 human multiple myeloma cells in vitro.

DEP domain containing mammalian target of rapamycin (mTOR)-interacting protein (DEPTOR) is an mTOR binding protein that is overexpressed in RPMI-8226 human multiple myeloma cells, and plays an important role in maintaining cell survival. However, knowledge on the effects of DEPTOR knockdown on the biological functions of RPMI­8226 human multiple myeloma cells, is limited. This study aimed to determine the role of DEPTOR in the proliferation, apoptosis and autophagy in these cells and to elucidate the mechanisms by which DEPTOR contributes to the chemosensitivity of myeloma cells. RNA interference was used to reduce the expression of DEPTOR. Cytotoxicity was evaluated by MTT assay. Apoptosis was examined by flow cytometry. DEPTOR mRNA and protein expression in RPMI­8226 cells treated with DEPTOR-specific short hairpin RNA (shRNA) was evaluated by RT-PCR, quantitative PCR and western blot analysis. The expression of apoptosis­associated proteins, autophagy­associated proteins, and the activation of the phosphoinositide 3­kinase (PI3K)/Akt signaling pathway were detected by western blot analysis. Autophagy was also measured by transmission electron microscopy and monodansylcadaverine (MDC). In this study, RPMI-8226 cells were transfected with the DEPTOR-specific shRNA, which resulted in the significant inhibition of the transcription and expression of DEPTOR. The downregulation of DEPTOR inhibited proliferation, enhanced the doxorubicin­induced growth inhibitory effects on RPMI-8226 cells, and increased the expression of cleaved caspase­3 and cleaved poly(ADP-ribose) polymerase (PARP). Moreover, the downregulation of DEPTOR suppressed autophagy and inhibited the activation of the PI3K/Akt signaling in RPMI­8226 cells. In conclusion, our data demonstrated that the downregulation of DEPTOR induces apoptosis, increases chemosensitivity to doxorubicin, and suppresses autophagy and the activation of the PI3K/Akt signaling pathway in RPMI­8226 human multiple myeloma cells.

A meta-analysis of unrelated donor umbilical cord blood transplantation versus unrelated donor bone marrow transplantation in acute leukemia patients.

Umbilical cord blood has emerged as an alternative stem cell source to bone marrow or peripheral blood stem cells. Umbilical cord blood transplantation (UCBT) is also potentially curative for acute leukemia. However, the effect of unrelated donor bone marrow transplantation (UBMT) and UCBT on the outcome of patients with acute leukemia has not been systematically reviewed. In the present meta-analysis, we systematically searched Cochrane Library, MEDLINE, EMBASE, and CNKI up to May 2011. Two reviewers extracted data independently. Seven studies totaling 3389 patients have been assessed. Pooled results found that the incidence of engraftment failure and transplantation-related mortality were higher in UCBT than in UBMT, and relative risks (RRs) were 4.27 (95% confidence interval [CI], 2.94-6.21) and 1.27 (95% CI, 1.01-1.59), respectively. The rates of acute and chronic graft-versus-host disease (GVHD) in the UCBT group were significantly lower than that in the UBMT group, and RRs were 0.71 (95% CI, 0.65-0.79) and 0.69 (95% CI, 0.52-0.91), respectively. The relapse rate was similar between the UCBT and UBMT group. The leukemia-free survival (LFS) and overall survival (OS) were significantly lower in the UCBT group than in the UBMT group; RRs were 1.14 (95% CI, 1.07-1.22) and hazard ratios (HRs) were 1.31 (95% CI, 1.16-1.48), respectively. Subgroup analysis showed that in patients with acute lymphoblastic leukemia (ALL), the survival was similar between UCBT and UBMT.

Knockdown of c-Met enhances sensitivity to bortezomib in human multiple myeloma U266 cells via inhibiting Akt/mTOR activity.

The c-Met is a receptor tyrosine kinase that is overexpressed in human myeloma cell lines and promotes the survival and drug resistance of myeloma cells. This study aimed to elucidate the mechanisms by which c-Met contributes to the chemoresistance in myeloma. Stable U266 cell line in which c-Met was effectively knockdown was employed and treated with bortezomib. Cytotoxicity was evaluated by MTT assay. Cell cycle profile and apoptosis were examined by cytometry analysis. The expression of cell cycle related proteins, and the activities of caspases and Akt/mTOR were detected by Western blot analysis. The c-Met knockdown in U266 cells decreased the average IC(50) of bortezomib, induced G0/G1 phase arrest, and increased caspase-mediated apoptosis in U266 cells exposed to bortezomib. In addition, c-Met knockdown decreased the level of cyclin D1 and increased the levels of p27 and cleaved caspase 3 and caspase 9. Moreover, the Akt/mTOR activity in U266 cells treated with bortezomib was downregulated upon c-Met knockdown and c-Met knockdown U266 cells recovered chemoresistance upon the overexpression of Akt and mTOR. Our data demonstrate that c-Met is a potential therapeutic target for multiple myeloma, and Akt/mTOR is a key signaling component through which c-Met protects multiple myeloma cells from chemotherapy-induced growth inhibition and apoptosis.

Allogeneic peripheral blood stem cell and bone marrow transplantation for hematologic malignancies: meta-analysis of randomized controlled trials.

Peripheral blood stem cells have emerged as an alternative to bone marrow for allogeneic transplantation. To elucidate the advantages and disadvantages of research evidence related to the effects of allogeneic peripheral blood stem cells transplantation (PBSCT) and bone marrow transplantation (BMT) for hematological malignancies, we conducted a systematic review of the literature of randomized controlled trials comparing PBSCT to BMT. We systematically searched Cochrane Library, MEDLINE, EMBASE and CNKI up to May 2011. Two reviewers independently identified the eligible studies and assessed the methodological quality of included trials. The relevant data were extracted and analysed using RevMan 5.1. Ten trials totaling 1224 patients have been assessed. Pooled comparisons of studies of PBSCT and BMT found that the overall survival in PBSCT group was non-significantly different from that in BMT group [RR 0.92, 95% CI (0.80-1.07)]. The disease-free survival and relapse rate in PBSCT group were significantly different from that in BMT group [RR 0.67, 95% CI (0.52-0.86) and RR 0.51, 95% CI (0.34-0.76), respectively]. The number of days to reach the absolute neutrophil and platelet count were shorter with PBSCT. The rates of acute and chronic graft-versus-host disease (GVHD) in PBSCT group were significantly higher than that in the BMT group. The mortality in PBSCT group was non-significantly different from that in BMT group. We concluded that PBSCT was associated with a similar overall survival and mortality, improved disease-free survival and a decrease in relapse, faster engraftment, more GVHD when compared with BMT in transplantation for hematologic malignancies.

The effect of tranexamic acid on blood loss and use of blood products in total knee arthroplasty: a meta-analysis.

PURPOSE: Studies have shown that tranexamic acid (TXA) reduces blood loss and transfusion need in patients undergoing total knee arthroplasty (TKA). However, no single study has been large enough to definitively determine whether the drug is safe and effective. We report a systematic review and meta-analysis of randomised controlled trials evaluating the efficacy and safety of TXA in reducing blood loss and transfusion in TKA. METHODS: A comprehensive literature search was done in Cochrane Library, MEDLINE, EMBASE, and CNKI. Two reviewers independently identified the eligible studies, assessed their methodological quality, and extracted data. The data were evaluated using the generic evaluation tool designed by the Cochrane Bone, Joint and Muscle Trauma Group. The relevant data were analyzed using RevMan 5.0. RESULTS: Fifteen randomized controlled trials involving 842 patients were included. The use of TXA reduced total blood loss by a mean of 487 ml [95% confidence interval (CI) -629 to -344], intra-operative blood loss by a mean of 127 ml (95% CI -313-59), and post-operative blood loss by a mean of 245 ml (95% CI -410 to -80). TXA led to a significant reduction in the proportion of patients requiring blood transfusion (risk difference -0.4). There were no significant differences in deep-vein thrombosis (DVT), pulmonary embolism, or other complications among the study groups. CONCLUSION: Meta-analysis indicates that TXA may reduce post-operative, total blood loss and transfusion in patients undergoing TKA. TXA led to a significant reduction in the proportion of patients requiring blood transfusion. LEVEL OF EVIDENCE: Therapeutic study (Systematic review of Level I studies with inconsistent results), Level II.

Anti-proliferative effects of cucurmosin on human hepatoma HepG2 cells.

We extracted cucurmosin (CUS) from the sarcocarp of Cucrubita moschata (pumpkin). Recently, a number of studies have indicated that CUS has cytotoxic properties and induces apoptosis in a number of human tumor cells. However, the detailed mechanisms are largely unknown. The aim of this study was to confirm CUS's anticancer activity on human hepatoma HepG2 cells in vitro and in vivo, and to elucidate the mechanism of its activity. MTT was used to detect the cytotoxic effects of CUS. Flow cytometry was used to analyze cell apoptosis and the cell cycle. Transmission electron microscopy was used to observe the morphology of apoptotic cells. Western blot analysis was performed to measure the protein expression of bax, bcl-2 and procaspase-3. The established orthotopic transplantation models of human hepatoma in NOD/SCID mice were tested for anticancer activities in vivo. The results showed that CUS inhibited the proliferation of HepG2 cells in vitro and in vivo. CUS induced apoptosis and arrested the cell cycle. In addition, CUS increased the protein expression of bax, but decreased the bcl-2 and procaspase-3 expression in HepG2 cells. Our data indicate that CUS has potential anticancer activity for human hepatoma, which can be attributed in part to its inhibition of proliferation and apoptosis, induced by decreasing the bcl-2:bax ratio and caspase-3 activation.

Knockdown of c-Met inhibits cell proliferation and invasion and increases chemosensitivity to doxorubicin in human multiple myeloma U266 cells in vitro.

c-Met, a receptor tyrosine kinase and its ligand, hepatocyte growth factor, are critical in cellular proliferation, motility and invasion and confer resistance to specific chemotherapeutic drugs. However, little is known about the impact of c-Met knockdown on the biological functions of human multiple myeloma U266 cells. The present study was designed to determine the role of c-Met in the proliferation and invasion of U266 cells, using RNA interference technology in vitro. In our study, the c-Met short hairpin RNA (shRNA) was successfully transfected into U266 cells, which resulted in the significant inhibition of transcription and expression of c-Met. The down-regulation of c-Met inhibited the proliferation potential, adherence and invasiveness of U266 cells, and also increased chemosensitivity to doxorubicin. The c-Met shRNA in U266 cells induced apoptosis and increased the accumulation of cleavage PARP and cleavage caspase-3. However, the expression of Bcl-2 and Bax did not change following the c-Met knockdown. Taken together, our data reveal that the down-regulation of c-Met inhibits proliferation and invasion and increases the chemosensitivity of U266 cells. Thus, the targeting of c-Met could be an effective therapeutic approach against multiple myeloma.