Vitamin C alleviates LPS-induced myocardial injury by inhibiting pyroptosis via the ROS-AKT/mTOR signalling pathway.

BACKGROUND: The efficacy of vitamin C in sepsis remains controversial. Whether vitamin C can alleviate lipopolysaccharide (LPS)-induced myocardial injury by inhibiting pyroptosis has not been studied. This study aimed to evaluate the effects of vitamin C on LPS-induced myocardial injury in vitro. METHODS: H9C2 cells were treated with indicated concentrations of LPS, and the cell viability was then assessed by CCK-8 assay. The levels of lactate dehydrogenase (LDH), CK-MB, IL-18 and IL-1ß were examined by enzyme-linked immunosorbent assay (ELISA). The levels of intracellular reactive oxygen species (ROS) were measured using the fluorescent probe dichlorodihydrofluorescein diacetate (DCFH-DA). Western blot assays were conducted to determine the levels of the ROS-associated protein nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) and pyroptosis-associated proteins, such as NOD-like receptor (NLR) family pyrin domain containing 3 (NLRP3), caspase-1 and gasdermin D (GSDMD). The AKT inhibitor MK-2206 was then applied to explore the signalling pathway. Finally, H9C2 cells were divided into the control group, LPS group, vitamin C + LPS group, and N-acetyl-L-cysteine (NAC) + LPS group. The intracellular ROS, levels of associated proteins, cell viability, and release of LDH, CK-MB, IL-18 and IL-1ß were examined. RESULTS: LPS decreased cell viability and induced ROS and pyroptosis in H9C2 cells in a dose-dependent manner. Moreover, LPS activated the AKT/mTOR pathway in H9C2 cells. The AKT inhibitor MK-2206 protected H9C2 cells from LPS-induced death by suppressing pyroptosis, without changing intracellular ROS level. Vitamin C significantly inhibited intracellular ROS and cell pyroptosis in LPS-treated H9C2 cells. Moreover, vitamin C suppressed the activation of the AKT/mTOR pathway. CONCLUSIONS: Our data suggest that vitamin C alleviates LPS-induced myocardial injury by inhibiting pyroptosis via the ROS-AKT/mTOR signalling pathway and thus provide novel insights into the prevention of sepsis-induced myocardial dysfunction.

Etiology of Nasal Bone Fracture: A Retrospective Analysis of 1,441 Patients in China.

ABSTRACT: Nasal bone fracture is the most common injury in the craniofacial area. Understanding the etiology of nasal bone fracture is important for the development of preventive public health programs. In this study, the authors retrospectively examined medical records to extract information about sex, age, injury time, injury cause, occupation, and place of residence (urban or rural) from 1441 patients with nasal bone fracture to investigate the etiology of nasal bone fracture in China. Among the 1441 patients, the ratio of males to females was 3.4:1. The mean patient age was 29.25 years. The most common occupation was student (31.02%). Violence was the most common cause of injury in male patients (35.82%), whereas slip-and-fall accidents were the most common cause in female patients (32.11%). Violence was the most common cause of injury in both urban and rural patients, and 74.19% were attacked by others without a weapon. This report provides important data about the etiology of nasal bone fracture in China and will help improve nasal bone fracture prevention measures.

[Cdc37 Expression in Multiple Myeloma and Its Role in Cell Proliferation].

OBJECTIVE: To investigate the expression of cell division cycle protein 37 (Cdc37) in multiple myeloma (MM) and its effect on MM cell proliferation. METHODS: The expression of Cdc37 mRNA in CD138+ cells derived from 63 newly diagnosed MM patients and 8 healthy people were detected by real-time quantitative PCR (RT-qPCR). Cdc37 was down-regulated by lentivirus in MM cell line NCI-H929. CCK-8 assay and soft agar clone formation assay were conducted to explore the role of Cdc37 on MM proliferation in vitro. To further verify the effect of Cdc37 on MM cell proliferation in vivo, NOD/SCID mice subcutaneous tumorigenesis model was established. Flow cytometry was carried out to explore the role of Cdc37 on cell cycle. Cell cycle associated proteins and NF-κB pathway were detected by Western blot (WB). RESULTS: Cdc37 was highly expressed in newly diagnosed CD138+cells compared with healthy people. After Cdc37 suppression by shRNA lentivirus infection in NCI-H929 cells, the proliferation of MM cells were decreased in vitro and in vivo. Compared with the control group, the ratio of cells arrested in G0/G1 phase significantly increased in NCI-H929-Cdc37 shRNA cells, the expression of cyclin D1 decreased, while the expression of p21 and p53 was significantly up-regulated. Meanwhile, the activation of NF-κB signaling pathway was hampered in NCI-H929-Cdc37 shRNA cells. CONCLUSION: Cdc37 is highly expressed in newly diagnosed MM patients. Inhibition of Cdc37 results in decreased proliferation activity and G0/G1 arrest in NCI-H929 cells. The possible mechanism may be to inhibit the activation of NF-κB signaling pathway.

Cdc37 suppression induces plasma cell immaturation and bortezomib resistance in multiple myeloma via Xbp1s.

Multiple myeloma (MM) is the second most prevalent hematologic malignancy. Although the use of bortezomib (BTZ) significantly improves MM therapy, intrinsic and acquired drug resistance to BTZ remains a major clinical problem. In this study, we find that Cdc37, a key co-chaperone of Hsp90, is downregulated in relapsed MM patients, especially after BTZ treatment, suggesting a link between Cdc37 and BTZ resistance. Suppression of Cdc37 or inhibition of Cdc37/Hsp90 association induces plasma cell dedifferentiation, quiescence of MM cells, and BTZ resistance in MM. Furthermore, we discover that Cdc37 expression correlates positively with Xbp1s, a critical transcription factor for plasma cell differentiation in MM samples. Depletion/inhibition of Cdc37 downregulates Xbp1s, while overexpression of Xbp1s in MM cell lines partially rescues plasma immaturation and BTZ resistance. It is suggested that Xbp1s may act as a key downstream effector of Cdc37. Experiments with a mouse model also demonstrate that Cdc37 inhibition promotes plasma cell immaturation, confers BTZ resistance, and increases MM progression in vivo. Together, we identify a critical factor and a new signaling mechanism that regulate plasma cell immaturation and BTZ resistance in MM cells. Our findings may constitute a novel strategy that overcomes BTZ resistance in MM therapy.

Secretory status of monoclonal immunoglobulin is related to the outcome of patients with myeloma: a retrospective study.

The treatment of multiple myeloma (MM) with proteasome inhibitor (PI) bortezomib has significantly improved the survival of patients with MM. The 26S proteasome inhibitor targets the unfolded protein response (UPR) by inhibiting proteasome degradation of ubiquitinated paraprotein, subsequently leading to the lethal accumulation of paraprotein within the endoplasmic reticulum. According to secretory status of monoclonal immunoglobulin, newly diagnosed MM (NDMM) is divided into measurable and unmeasurable disease, which includes oligosecretory, nonsecretory, and nonproducer myeloma. The present study analyzed the clinical characteristics of 822 patients with NDMM who had either measurable or unmeasurable diseases and received bortezomib- or thalidomide-based therapies. Our results showed that the median progression-free survival (PFS) and overall survival (OS) of patients with MM was significantly longer in patients with measurable disease than those in oligosecretory, nonsecretory, and nonproducer MM (PFS: 27, 18, 19, and 2.0 months, respectively [P < .001]; OS: 51, 30, 22, and 2.0 months, respectively [P < .001]). Within the unmeasurable group, patients with nonproducer myeloma showed the shortest PFS and OS. Importantly, compared with thalidomide treatment, bortezomib significantly improved the PFS and OS of patients with MM with measurable disease (PFS: 25 and 33 months [P = .022], respectively; OS: 41 and 58 months [P < .001], respectively), but not those with unmeasurable disease (PFS: 18 and 16 months [P = .617], respectively; OS: 22 and 27 months [P = .743], respectively). Our results indicate that bortezomib-based therapy performed no better than thalidomide-based treatment in patients with unmeasurable MM. The results need to be confirmed in other patient cohorts, preferably in the context of a prospective trial.

[Cheek blood sampling of mice].

OBJECTIVE: To explore the method of cheek blood sampling in mice in continuous blood test. METHODS: Cheek blood sampling was carried out in 10 9-week-old mice once every 2-3 days. The volumes of blood samples were recorded. Reactions of the mice were observed. RESULTS: Cheek blood sampling collected 0.3-0.6 ml of blood every time, and did not affect the normal activities of the mice. The blood sampling could be repeated every 2-3 days. CONCLUSIONS: Cheek blood sampling has several advantages including being capable to draw adequate blood, simple and easy to operate, well tolerated, and ethical in treating laboratory animals.

Serum high expression of miR-214 and miR-135b as novel predictor for myeloma bone disease development and prognosis.

Multiple myeloma (MM) originates from malignant plasma cells, leading to multiple destructive lytic bone lesions that occur in more than 80% of MM patients. MicroRNAs have been reported to be involved in development of bone lesions in MM. However, the circulating microRNA as diagnostic and prognostic biomarkers for bone lesions has not been elucidated yet. In this study, we identified differentially expressed miRNAs that are potentially involved in myeloma-related bone disease in serum of MM patients. MiR-214 and miR-135b was shown to be increased in serum of MM patients with bone lesions. Serum level of miR-214 and miR-135b was highly correlated with the severity of lytic bone lesions and demonstrated as a diagnostic tool for identifying bone diseases based on results of a receiver operating characteristic analysis (ROC). In addition, patients with high levels of serum miR-214 had a dismal survival with significantly shortened progression free survival (PFS) and overall survival (OS). Interestingly, bisphosphonates treatment significantly extended PFS and OS in patients with higher level of miR-214 comparing to patients without bisphosphonates treatment. Taken together, our findings revealed the significance of circulating miR-214 and miR-135b levels in detection of bone disease and in prediction of prognosis of patients with multiple myeloma, suggesting its potential clinical applications. The result of this study also set the foundation for searching more circulating miRNA as biomarker for tumor bone lesions.

Detection of recurrent cytogenetic aberrations in multiple myeloma: a comparison between MLPA and iFISH.

Multiple myeloma (MM) is a genetically heterogeneous disease with diverse clinical characteristics and outcomes. Recently, multiplex ligation-dependent probe amplification (MLPA) has emerged as an effective and robust method for the detection of cytogenetic aberrations in MM patients. In the present study, MLPA analysis was applied to analyze cytogenetics of CD138 tumor cells of 59 MM samples, and its result was compared, retrospectively, with the interphase fluorescence in situ hybridization (iFISH) data. We firstly established the normal range of each of the 42 diagnostic probes using healthy donor samples. A total of 151 aberrations were detected in 59 patient samples, and 49/59 cases (83.1%) harbored at least one copy number variation. Overall, 0-7 aberrations were detected per case using MLPA, indicating the heterogeneity and complexity of MM cytogenetics. We showed the high efficiency of MLPA and the high congruency of the two methods to assess cytogenetic aberrations. Considering that MLPA analysis is not reliable when the aberration only exits in a small population of tumor cells, it is essential to use both MLPA and iFISH as complementary techniques for the diagnosis of MM.

Anti-tumor activity of the proteasome inhibitor BSc2118 against human multiple myeloma.

Introduction of bortezomib, the first generation of proteasome inhibitor, has significantly improved the median overall survival of patients with multiple myeloma (MM). However, the dose-limiting adverse events and acquired drug resistance limit its long-term usage. Here, we report in vitro and in vivo anti-MM activity of the irreversible proteasome inhibitor BSc2118. BSc2118 inhibited the chymotrypsin-like (CT-L) proteasome activity, accompanied by accumulation of ubiquitinated proteins. BSc2118 suppressed tumor cell growth through induction of G2/M phase arrest and induced apoptosis via activation of the apoptotic signaling cascade, in association with up-regulation of p53 and p21. Importantly, BSc2118 was active in vitro against MM cells' acquired bortezomib resistance. Of note, BSc2118 also displayed a novel anti-angiogenesis activity both in vitro and in vivo. Lastly, BSc2118 exhibited a broader safety dose range and higher anti-tumor efficacy in vivo in a human MM xenograft mouse model, compared to bortezomib. Together, these findings indicate the in vitro and in vivo anti-MM activities of BSc2118 through induction of cell cycle arrest and apoptosis, as well as inhibition of tumor angiogenesis. They also suggest that BSc2118 might, at least in vitro, partially overcome acquired bortezomib resistance, likely associated with inhibition of autophagy.

[The impact of renal function on prognostic value of ß2-microglobulin of ISS stage system in multiple myeloma patients--Clinical data analysis of 666 patients in a single center].

OBJECTIVE: To investigate the influence of renal function on the level of ß2-microglobulin (ß2-MG) as prognostic factor in newly diagnosed multiple myeloma (MM) patients, and to analyze the overall survival (OS) in different level of ß2-MG with relatively normal or abnormal renal function in MM patients. METHODS: According to the level of ß2-MG, 666 newly diagnosed MM patients were divided into three groups as ß2-MG<3.5, 3.5-<5.5, ≥5.5 mg/L. According to the level of serum creatinine, these patients were divided into two groups:serum creatinine <177 µmol/L as relatively normal group, serum creatinine ≥177 µmol/L as abnormal group. RESULTS: Among 666 patients, there were 416 male and 250 female, the median age was 58 (25-86) years old. Comparison of OS among ß2-MG<3.5, 3.5-<5.5, ≥5.5 mg/L groups indicated that the median OS of the three groups were 85.75 (95% CI 70.99-100.50), 47.25 (95% CI 40.98-53.53) and 35.05 (95% CI 30.75-39.35) months, respectively (P<0.01). Comparison of OS between serum creatinine <177 and ≥177 mmol/L groups, the median OS of the two groups were 64.67 (95% CI 56.57-72.77) and 32.74 (95% CI 27.74-37.73) months, respectively (P<0.01). In ß2-MG≥5.5 mg/L, the median OS of relatively normal and abnormal groups were 37.25 (95% CI 31.45-43.06) and 32.55 (95% CI 26.26-38.83) months, respectively (P=0.142). CONCLUSION: High level of ß2-MG and renal function correlated with shorter survival of MM patients. Higher level of ß2-MG with abnormal renal function can't change the prognostic value of ß2-microglobulin on MM.

Downregulated miR-33b is a novel predictor associated with disease progression and poor prognosis in multiple myeloma.

MiRNAs located at chromosome fragile sites play important roles in regulating critical genes associated with myeloma pathogenesis, disease progression and drug resistance. Our previous results have identified miR-33b (located in chromosome 17p) was one of the dysregulated miRNAs in the sera of newly diagnosed MM patients. However, little is known about its expression pattern in myeloma tumor cells and its prognostic value in MM patients. In the present study, we investigated the expression pattern of miR-33b in 58 newly diagnosed, 11 relapsed, 12 remission MM patients and 18 health donors by quantitative real-time PCR. Our results showed the expression of miR-33b was obviously down-regulated in newly diagnosed and relapsed MM patients compared to remission patients and health donors (p<0.001). Moreover, patients with del(13q), del(17p), t(4;14) and high-risk genetic abnormalities have lower expression levels of miR-33b compared to patients without those of abnormalities (p=0.032, 0.018, 0.034, 0.005). Survival analysis showed patients with miR-33b low expression had significantly shortened PFS (p=0.016) and OS (p=0.033) and might be associated with drug resistance to bortezomib-based treatment. Our data suggest that down-regulated miR-33b might be a novel predictor associated with disease progression and poor prognosis in MM.

Heterogeneous chromosome 12p deletion is an independent adverse prognostic factor and resistant to bortezomib-based therapy in multiple myeloma.

The deletion of 12p (del(12p)) has been described as a novel negative prognostic marker in multiple myeloma (MM) and has gained increasing attention in recent years. However, its impact on MM is still controversial. In this study, we comprehensively evaluated the clinical impact of 12p13 deletion using fluorescence in situ hybridization (FISH) on 275 newly diagnosed MM cases treated in a prospective, non-randomized clinical trial (BDH 2008/02). The results showed that deletion of 12p13 was detected in 10.5% of newly diagnosed cases and associated with multiple indicators for high tumor burden including ISS III, BM plasmacytosis larger than 50%, and renal lesion. Moreover, the cases with 12p13 deletion typically had higher incidence of del(17p), IGH translocation and t(4;14). Patients with del(12p) conferred significantly adverse prognosis for PFS and OS, even in patients subjected to bortezomib-based therapy. When adjusted to the established prognostic variables including del(13q), del(17p), t(4;14), amp(1q21), ISS stage and LDH, del(12p13) remained the powerful independent adverse factor for PFS (P = 0.007) and OS (P = 0.032). In addition, del(12p13) combined with high ß2-MG, high LDH and bone lesion can further identify subpopulations with high-risk features. Our results strongly supported that del(12p13) can be used as a valuable prognostic marker in MM.

The impact of clone size on the prognostic value of chromosome aberrations by fluorescence in situ hybridization in multiple myeloma.

PURPOSE: Accumulating evidence indicates that intratumor heterogeneity is prevalent in multiple myeloma and that a collection of multiple, genetically distinct subclones are present within the myeloma cell population. It is not clear whether the size of clonal myeloma populations harboring unique cytogenetic abnormalities carry any additional prognostic value. EXPERIMENTAL DESIGN: We analyzed the prognostic impact of cytogenetic aberrations by fluorescence in situ hybridization at different cutoff values in a cohort of 333 patients with newly diagnosed myeloma and 92 patients with relapsed myeloma. RESULTS: We found that nearly all IgH-related arrangements were observed in a large majority of the purified plasma cells; however, 13q deletion, 17p deletion, and 1q21 amplification appeared in different percentages within the malignant plasma cell population. Based on the size of subclones carrying these cytogenetic aberrations, the patients were divided into four groups: 0%-10%, 10.5%-20%, 20.5%-50%, and >50%. Receiver-operating characteristics analysis was applied to determine the optimal cutoff value with the greatest differential survival and showed that the most powerful clone sizes were 10% for 13q deletion, 50% for 17p deletion, and 20% for 1q21 gains, which provided the best possible cutoffs for predicting poor outcomes. CONCLUSIONS: Our study indicated that the impact of clone size on prognostic value varies between specific genetic abnormalities. Prognostic value was observed for even a subgroup of plasma cells harboring the cytogenetic aberration of 13q deletion and 1q21 gains; however, 17p deletion displayed the most powerful cutoff for predicting survival only if the predominant clones harbored the abnormality.

Multiple myeloma patients with low proportion of circulating plasma cells had similar survival with primary plasma cell leukemia patients.

The common features shared by primary plasma cell leukemia (pPCL) and multiple myeloma (MM) with circulating plasma cells (CPCs) are peripheral blood invasion and expansion of plasma cells independent of the protective bone marrow (BM) microenvironment niche. However, few studies have addressed the relationship between pPCL and MM with CPCs. Here, we quantitated the number CPCs by conventional morphology in 767 patients with newly diagnosed MM; their clinic features were compared with those of 33 pPCL cases. When the presence of CPCs was defined as more than 2 % plasma cells per 100 nucleated cells on Wright-Giemsa stained peripheral blood smears, the incidence of MM with CPCs was 14.1 % in newly diagnosed MM. Patients with CPCs shared many clinical features with pPCL, especially clinical parameters related to tumor burden. However, no commonalities were found in immunophenotyping and cytogenetics. The prognosis of pPCL was poor, with a median progression free survival (PFS) of 12 months and an overall survival (OS) of 15 months. MM patients with CPCs had a clearly inferior PFS and OS as compared with the control cohort. Most interestingly, although the CPCs were not high enough to meet the diagnostic criteria for pPCL, the survival of MM patients with CPCs was comparable with that of pPCL, with a median PFS of 17 months and an OS of 25 months.

Low serum miR-19a expression as a novel poor prognostic indicator in multiple myeloma.

Multiple myeloma (MM) is the second most common hematologic malignancy characterized by the clonal expansion of plasma cells. Despite continuing advances, novel biomarkers are needed for diagnosis and prognosis of MM. In our study, we characterized the diagnostic and prognostic potential of circulating microRNAs (miRNAs) in MM. Serum miRNA levels were analyzed in 108 newly diagnosed symptomatic MM patients and 56 healthy donors (HDs). Our analysis identified 95 dysregulated miRNAs in newly diagnosed MM patients. Of the 95 dysregulated miRNAs, dysregulation of miR-19a, miR-92a, miR-214-3p, miR-135b-5p, miR-4254, miR-3658 and miR-33b was confirmed by quantitative reverse transcription PCR (RT-qPCR). Receiver operating characteristic analysis revealed that a combination of miR-19a and miR-4254 can distinguish MM from HD with a sensitivity of 91.7% and specificity of 90.5%. Decreased expression of miR-19a was positively correlated with international staging system advancement, del(13q14) and 1q21 amplification. Furthermore, downregulation of miR-19a resulted in significantly decreased progression-free survival (PFS) and overall survival (OS). Our analysis indicated that the poor prognostic correlation of miR-19a expression was independent of genetic abnormalities in MM. Multivariate analysis revealed that miR-19a was a significant predictor of shortened PFS and OS. Interestingly, although miR-19a levels portend a poor prognosis, patients with low miR-19a levels had an improved response to bortezomib compared to those with high miR-19a profile. Patients with downregulated miR-19a experienced a significantly extended survival upon bortezomib-based therapy. These data demonstrate that the expression patterns of serum microRNAs are altered in MM, and miR-19a levels are a valuable prognostic marker to identify high-risk MM.

Cytogenetic and clinical marks for defining high-risk myeloma in the context of bortezomib treatment.

Multiple myeloma (MM) is a heterogeneous disease, and the benefit from bortezomib treatment is not uniform among all patients subgroups. Currently, little information is available to predict patients response to bortezomib treatment. In this study, we aimed to identify patients benefiting minimally from bortezomib as part of first-line therapy and to define high-risk MM in the context of bortezomib treatment. We compared the effect of a bortezomib-based treatment (arm B) with that of a treatment without bortezomib (arm A) on different genetic patient subgroups in a series of 273 cases of newly diagnosed MM. These patients were enrolled in a prospective, non-randomized clinical trial (BDH 2008/02). A subgroup of patients exhibiting little benefit from bortezomib treatment was identified. These patients had at least one of the following characteristics: del(17p13), 1q21 gain, or high lactate dehydrogenase levels. In this subgroup, survival of patients treated with bortezomib was comparable (progression-free survival: 14.0 vs. 15.0 months, p = 0.992; overall survival: 21.0 vs. 14.0 months, p = 0.472) to that of patients undergoing thalidomide-based treatment. We propose that all patients with newly diagnosed MM should be evaluated for these three markers before bortezomib treatment. Other novel drugs and alternative therapeutic strategies are needed for patients with such markers.

[Expression of SOX11 mRNA in mantle cell lymphoma and its clinical significance].

OBJECTIVE: To investigate the expression level of SOX11 mRNA in mantle cell lymphoma (MCL) and other B-cell non-Hodgkin lymphoma (B-NHL) and its prognostic value in MCL. METHODS: The expression level of SOX11 mRNA in 80 B-NHL patients were determined by real-time quantitative RT-PCR, GAPDH was used as internal control. The dispersion of SOX11 expression ratio of groups with different prognostic factors was described by Mann-Whitney U test. RESULTS: The SOX11 mRNA expression level was 2.90 (0.75 - 4.63) in 80 B-NHL patients, and the expression level was significantly higher in MCL than that in other B-NHL (P = 0.014). The SOX11 expression level was statistically lower in the group of MCL with hyperleukocytosis, 12 trisomy, MYC amplification and therapeutic effect < PR (P = 0.042, 0.013, 0.028, 0.009) than that of MCL in other group. But SOX11 expression was not associated with MCL international prognostic index (MIPI) (P = 0.333), lactate dehydrogenase (LDH) (P = 0.790), ATM mutation (P = 0.865) and P53 deletion (P = 0.116). The progression free survival (PFS) and overall survival (OS) were significantly longer in the MCL patients with high level of SOX11 than that of other MCL patients. CONCLUSION: There was statistically significant differences in SOX11 mRNA expression between MCL with other B-NHL. SOX11 maybe a good prognostic factor in MCL.

[Regulation of miRNA-15a/-16 expression on the drug resistance of myeloma cells].

OBJECTIVE: To explore the effects and mechanism of bone marrow stromal cells (BMSCs) on the drug resistance of multiple myeloma (MM). METHODS: Fresh untreated MM patient (5 samples) and health donor (5 samples) bone marrow samples were collected from May 2011 to July 2011 at our hospital. Their BMSCs were separated respectively. The supernatant expression of cytokines in BMSCs was detected by enzyme-linked immunosorbent assay (ELISA). Myeloma cells were co-cultured with BMSCs and treated with melphalan or bortezomib. Cell proliferation and miRNA-15a/-16 expression of myeloma cells were measured in different culture conditions with thiazoyl blue tetrazolium bromide (MTT) assay and quantitative real-time PCR (qRT-PCR). miRNA-15a was transfected into myeloma cells. And the miRNA-15a functions on cell cycle and cell apoptosis were detected by flow cytometry. RESULTS: ELISA assay showed that cytokine IL-6 and VEGF were at higher levels in MM-BMSCs than healthy BMSCs ((189 ± 9) vs (115 ± 15) pg/ml, (1497 ± 40) vs (1239 ± 21) pg/ml, both P < 0.05). The miRNA-15a/-16 expressions of myeloma cells were up-regulated after the treatment of melphalan and bortezomib (all P < 0.05). However, the miRNA-15a/-16 up-regulation by melphalan or bortezomib became inhibited when MM cells were co-cultured with MM-BMSCs (melphalan: 4.690 ± 0.050 vs 34.440 ± 4.100, 0.760 ± 0.070 vs 12.030 ± 1.020, bortezomib: 1.440 ± 0.230 vs 11.480 ± 1.488, 0.880 ± 0.040 vs 3.680 ± 0.420, all P < 0.05). Furthermore, IL-6 suppressed the expression of miRNA-15a/-16 in a dose and time-dependent pattern. The transfection of miRNA-15a led to the arrest of MM cell cycle in G(1)/S phase. CONCLUSIONS: BMSCs suppress the proliferation of myeloma cells and regulate the drug sensitivity of myeloma cells through the inhibited expression of miRNA-15a/-16. IL-6 plays a pivotal role in the occurrence of drug resistance.