[Effect and mechanism of adipocyte co-culture on aquaporin-9 expression in HepG2 cells].

Objective: To observe the effect of differentiated mature adipocytes on hepatic steatosis and aquaporin-9 (AQP9) expressions in HepG2 cells and further explore its possible mechanism of action. Methods: Human preadipocytes were cultured and differentiated to full maturity. HepG2 cells were co-cultured with non-differentiated adipocytes and differentiated mature adipocytes for 48 h, and then labeled as control group and experimental group. Oil red O staining and intracellular triglyceride content were performed on co-cultured HepG2 cells and simultaneous changes in phosphatidylinositol 3-kinase (PI3K) - serine/threonine kinase (Akt) signaling pathway, and AQP9 mRNA and protein levels were detected. The experimental group was co-cultured with recombinant human insulin-like growth factor-I (IGF-I), with the addition of 100ng/ml PI3K-Akt pathway agonist, labeled as experimental group + IGF-I group. The activation of PI3K-Akt pathway was verified by Western blotting (WB). The expression of AQP9 was detected by RT-q PCR and WB. The recombinant lentivirus LV-AQP9 or empty-loaded virus LV-PWPI was transfected with HepG2 cells by recombinant lentiviral transfection tecnique, and labeled as HepG2-AQP9 and HepG2-PWPI. The transfection efficiency was assessed by confocal laser scanning microscopy and RT-qPCR and WB detected the change of AQP9 expression level after virus transfection. Afterwards, the stable over-expressed HepG2-AQP9 cells and the empty-loaded HepG2-PWPI cells were co-cultured with differentiated mature adipocytes for 48h, and labeled as HepG2-AQP9 co-culture group, and then intracellular triglyceride content were detected with Oil red O staining. Finally, IGF-I was added to the HepG2-AQP9 co-culture group, which was recorded as HepG2-AQP9 co-culture + IGF-I group. Intracellular triglyceride content was detected with Oil red O staining, and WB verified PI3K-Akt signaling pathway activation and changes in AQP9 mRNA and protein levels. A t-test was used to compare the two independent samples. Results: The intracellular lipid droplets and triglyceride content (0.052 ± 0.005) in the experimental group was increased significantly than the control group (0.033 ± 0.003) (t= 5.225,P= 0.006), suggesting that adipocyte co-culture had induced steatosis in HepG2 cells. RT-qPCR and WB results indicated that the expression levels of AQP9 mRNA (3.615 ± 0.330) and protein levels (0.072 ± 0.005) in the experimental group were significantly higher than the control group (t= 13.708, 11.225,P= 0.005, < 0.001). WB results showed that the expression level of phosphorylated Akt (p-Akt) protein (0.116±0.003) in the experimental group was significantly lower than the control group (0.202 ± 0.003) (t= 27.136,P< 0.001). The total Akt protein was constant, and the p-Akt/total Akt (0.182 ± 0.017)was significantly lower than the control group (0.327 ± 0.019) (t= 2.431,P= 0.001), suggesting that adipocyte co-culture had inhibited PI3K- Akt signaling pathway in HepG2 cells and up-regulated the expression level of AQP9. WB results indicated that the expression level of p-Akt protein (0.194 ± 0.021) in the experimental group + IGF-I group was significantly higher than the experimental group (0.132 ± 0.003) (t= 5.082,P= 0.007). The total Akt protein was constant, and the p-Akt/total Akt (0.281 ± 0.009) was significantly higher than the control group (0.184 ± 0.132) (t= 10.311,P< 0.001). Simultaneously, RT-qPCR and WB results indicated that the expression levels of AQP9 mRNA (0.327 ± 0.347) and protein levels (0.042 ± 0.004) in the experimental group + IGF-I group were significantly lower than the experimental group (t= 33.573, 5.598,P< 0.001, 0.005), suggesting that adipocyte co-culture had possibility to regulate the expression level of AQP9 through the PI3K-Akt pathway. Confocal laser microscopy analysis showed that the transfection efficiency was more than 90%. RT-q PCR and WB results indicated that the expression levels of AQP9 mRNA and protein levels (0.373 ± 0.221) in HepG2-AQP9 group were significantly higher than HepG2-PWPI group (t=14.953, 28.931,P= 0.002 and 0.000), suggesting that the stable overexpression of AQP9 cell line was successfully constructed. The intracellular lipid droplets and triglyceride content in HepG2-AQP9 co-culture group was significantly increased (t= 5.478, 5.369,P= 0.005) than HepG2-PWPI co-culture group and HepG2-AQP9 co-culture+ IGF-I group, suggesting that the increased expression of AQP9 had promoted HepG2 steatosis in co-cultured adipocytes. WB results showed the expression levels of p-Akt protein (0.168 ± 0.006) and p-Akt/total Akt (0.265±0.009) in HepG2-AQP9 co-culture + IGF-1 group was significantly increased (t= 16.311, 8.769,P< 0.001) than HepG2-AQP9 co-culture group, while the expression levels of AQP9 mRNA (0.327 ± 0.034) and protein (0.375 ± 0.025) was significantly decreased (t= 33.573, 9.146,P< 0.001 and 0.001). Conclusion: Adipocytes co-culture can induce steatosis in HepG2 cells, and may participate in inhibiting PI3K-Akt signaling pathway to upregulate the expression of AQP9 in steatotic HepG2 cells.

The effects of Biodentine/polycaprolactone three-dimensional-scaffold with odontogenesis properties on human dental pulp cells.

AIM: To determine the feasibility of using three-dimensional printed Biodentine/polycaprolactone composite scaffolds for orthopaedic and dental applications. The physicochemical properties and the odontogenic differentiation of human dental pulp cells (hDPCs) were investigated. METHODOLOGY: Biodentine was well-suspended in ethanol and dropped slowly into molten polycaprolactone with vigorous stirring. The Biodentine/polycaprolactone composite scaffolds were then fabricated into controlled macropore sizes and structures using an extrusion-based three-dimensional (3D) printer. The mechanical properties, bioactivity, and the proliferation and odontogenic differentiation of human dental pulp cells (hDPCs) cultured on the scaffolds were evaluated. RESULTS: Biodentine/polycaprolactone scaffolds had uniform macropores 550 µm in size with established interconnections and a compressive strength of 6.5 MPa. In addition, the composite scaffolds exhibited a good apatite-forming ability and were capable of supporting the proliferation and differentiation of hDPCs. CONCLUSION: The composite scaffolds fabricated by an extrusion-based 3D printing technique had similar characteristics to Biodentine cement, including bioactivity and the ability to promote the differentiation of hDPCs. These results indicate that the composite scaffold would be a candidate for dental and bone regeneration.

Effects of short-term step aerobics exercise on bone metabolism and functional fitness in postmenopausal women with low bone mass.

Measurement of bone turnover markers is an alternative way to determine the effects of exercise on bone health. A 10-week group-based step aerobics exercise significantly improved functional fitness in postmenopausal women with low bone mass, and showed a positive trend in reducing resorption activity via bone turnover markers. INTRODUCTION: The major goal of this study was to determine the effects of short-term group-based step aerobics (GBSA) exercise on the bone metabolism, bone mineral density (BMD), and functional fitness of postmenopausal women (PMW) with low bone mass. METHODS: Forty-eight PMW (aged 58.2 ± 3.5 years) with low bone mass (lumbar spine BMD T-score of -2.00 ± 0.67) were recruited and randomly assigned to an exercise group (EG) or to a control group (CG). Participants from the EG attended a progressive 10-week GBSA exercise at an intensity of 75-85 % of heart rate reserve, 90 min per session, and three sessions per week. Serum bone metabolic markers (C-terminal telopeptide of type 1 collagen [CTX] and osteocalcin), BMD, and functional fitness components were measured before and after the training program. Mixed-models repeated measures method was used to compare differences between the groups (α = 0.05). RESULTS: After the 10-week intervention period, there was no significant exercise program by time interaction for CTX; however, the percent change for CTX was significantly different between the groups (EG = -13.1 ± 24.4 % vs. CG = 11.0 ± 51.5 %, P < 0.05). While there was no significant change of osteocalcin in both groups. As expected, there was no significant change of BMD in both groups. In addition, the functional fitness components in the EG were significantly improved, as demonstrated by substantial enhancement in both lower- and upper-limb muscular strength and cardiovascular endurance (P < 0.05). CONCLUSION: The current short-term GBSA exercise benefited to bone metabolism and general health by significantly reduced bone resorption activity and improved functional fitness in PMW with low bone mass. This suggested GBSA could be adopted as a form of group-based exercise for senior community.

MiR-16 mediates trastuzumab and lapatinib response in ErbB-2-positive breast and gastric cancer via its novel targets CCNJ and FUBP1.

ErbB-2 amplification/overexpression accounts for an aggressive breast cancer (BC) subtype (ErbB-2-positive). Enhanced ErbB-2 expression was also found in gastric cancer (GC) and has been correlated with poor clinical outcome. The ErbB-2-targeted therapies trastuzumab (TZ), a monoclonal antibody, and lapatinib, a tyrosine kinase inhibitor, have proved highly beneficial. However, resistance to such therapies remains a major clinical challenge. We here revealed a novel mechanism underlying the antiproliferative effects of both agents in ErbB-2-positive BC and GC. TZ and lapatinib ability to block extracellular signal-regulated kinases 1/2 and phosphatidylinositol-3 kinase (PI3K)/AKT in sensitive cells inhibits c-Myc activation, which results in upregulation of miR-16. Forced expression of miR-16 inhibited in vitro proliferation in BC and GC cells, both sensitive and resistant to TZ and lapatinib, as well as in a preclinical BC model resistant to these agents. This reveals miR-16 role as tumor suppressor in ErbB-2-positive BC and GC. Using genome-wide expression studies and miRNA target prediction algorithms, we identified cyclin J and far upstream element-binding protein 1 (FUBP1) as novel miR-16 targets, which mediate miR-16 antiproliferative effects. Supporting the clinical relevance of our results, we found that high levels of miR-16 and low or null FUBP1 expression correlate with TZ response in ErbB-2-positive primary BCs. These findings highlight a potential role of miR-16 and FUBP1 as biomarkers of sensitivity to TZ therapy. Furthermore, we revealed miR-16 as an innovative therapeutic agent for TZ- and lapatinib-resistant ErbB-2-positive BC and GC.

Spatiotemporal control of estrogen-responsive transcription in ERα-positive breast cancer cells.

Recruitment of transcription machinery to target promoters for aberrant gene expression has been well studied, but underlying control directed by distant-acting enhancers remains unclear in cancer development. Our previous study demonstrated that distant estrogen response elements (DEREs) located on chromosome 20q13 are frequently amplified and translocated to other chromosomes in ERα-positive breast cancer cells. In this study, we used three-dimensional interphase fluorescence in situ hybridization to decipher spatiotemporal gathering of multiple DEREs in the nucleus. Upon estrogen stimulation, scattered 20q13 DEREs were mobilized to form regulatory depots for synchronized gene expression of target loci. A chromosome conformation capture assay coupled with chromatin immunoprecipitation further uncovered that ERα-bound regulatory depots are tethered to heterochromatin protein 1 (HP1) for coordinated chromatin movement and histone modifications of target loci, resulting in transcription repression. Neutralizing HP1 function dysregulated the formation of DERE-involved regulatory depots and transcription inactivation of candidate tumor-suppressor genes. Deletion of amplified DEREs using the CRISPR/Cas9 genomic-editing system profoundly altered transcriptional profiles of proliferation-associated signaling networks, resulting in reduction of cancer cell growth. These findings reveal a formerly uncharacterized feature wherein multiple copies of the amplicon congregate as transcriptional units in the nucleus for synchronous regulation of function-related loci in tumorigenesis. Disruption of their assembly can be a new strategy for treating breast cancers and other malignancies.

An in vitro bioassay for the quantitative evaluation of mosquito repellents against Stegomyia aegypti (=Aedes aegypti) mosquitoes using a novel cocktail meal.

To assess the efficacy of new insect repellents, an efficient and safe in vitro bioassay system using a multiple-membrane blood-feeding device and a cocktail meal was developed. The multiple-membrane blood-feeding device facilitates the identification of new insect repellents by the high-throughput screening of candidate chemicals. A cocktail meal was developed as a replacement for blood for feeding females of Stegomyia aegypti (=Aedes aegypti) (L.) (Diptera: Culicidae). The cocktail meal consisted of a mixture of salt, albumin and dextrose, to which adenosine triphosphate was added to induce engorging. Feeding rates of St. aegypti on the cocktail meal and pig blood, respectively, did not differ significantly, but were significantly higher than the feeding rate on citrate phosphate dextrose-adenine 1 (CPDA-1) solutions, which had been used to replace bloodmeals in previous repellent assays. Dose-dependent biting inhibition rates were analysed using probit analysis. The RD(50) (the dose producing 50% repellence of mosquito feeding) values of DEET, citronella, carvacrol, geraniol, eugenol and thymol were 1.62, 14.40, 22.51, 23.29, 23.83 and 68.05 µg/cm(2), respectively.

Role of the p38 pathway in mineral trioxide aggregate-induced cell viability and angiogenesis-related proteins of dental pulp cell in vitro.

AIM: To investigate the influence of mineral trioxide aggregate (MTA) on angiogenesis of primary human dental pulp cells (hDPCs) via the MAPK pathway, in particular p38. METHODOLOGY: Human dental pulp cells were cultured with MTA to angiogenesis, after which cell viability, ion concentration, osmolality, NO secretion, the von Willebrand factor (vWF) and angiopoietin-1 (Ang-1) protein expression were examined. PrestoBlue(®) was used for evaluating the proliferation of hDPCs. An enzyme-linked immunosorbent assay was employed to determine vWF and Ang-1 protein secretion in hDPCs cultured on MTA and the control. Cells cultured on the tissue culture plate without the cement were used as the control. The t-test was used to evaluate the significance of the differences between the mean values. RESULTS: Mineral trioxide aggregate elicited a significant (P < 0.05) increased viability compared with the control (15%, 16% and 13% on days 1, 3 and 5 of cell seeding, respectively). MTA consumed calcium and phosphate ions, and released more Si ions in the medium. MTA significantly (P < 0.05) increased the osmolality of the medium to 313, 328 and 341 mOsm kg(-1) after 1, 3 and 5 days, respectively. P38 was activated through phosphorylation, and the phosphorylation kinase was investigated in the cell system after being cultured with MTA. Expression levels for Ang-1 and vWF in hDPCs on MTA were higher than those of the MTA + p38 inhibitor (SB203580) group (P < 0.05) at all of the time-points. CONCLUSIONS: Mineral trioxide aggregate was able to activate the p38 pathway in hDPCs cultured in vitro. Moreover, Si increased the osmolality required to facilitate the angiogenic differentiation of hDPCs via the p38 signalling pathway. When the p38 pathway was blocked by SB203580, the angiogenic-dependent protein secretion decreased. These findings verify that the p38 pathway plays a key role in regulating the angiogenic behaviour of hDPCs cultured on MTA.

Elevated snoRNA biogenesis is essential in breast cancer.

Hyperactive ribosomal biogenesis is widely observed in cancer, which has been partly attributed to the increased rDNA transcription by Pol I in cancer. However, whether small nucleolar RNAs (snoRNAs), a class of non-coding RNAs crucial in ribosomal RNA (rRNA) maturation and functionality, are involved in cancer remains elusive. We report that snoRNAs and fibrillarin (FBL, an enzymatic small nucleolar ribonucleoprotein, snoRNP) are frequently overexpressed in both murine and human breast cancer as well as in prostate cancers, and significantly, that this overexpression is essential for tumorigenicity in vitro and in vivo. We demonstrate that when the elevated snoRNA pathway is suppressed, the tumor suppressor p53 can act as a sentinel of snoRNP perturbation, the activation of which mediates the growth inhibitory effect. On the other hand, high level of FBL interferes with the activation of p53 by stress. We further show that p53 activation by FBL knockdown is not only regulated by the ribosomal protein-MDM2-mediated protein stabilization pathway, but also by enhanced PTB-dependent, cap-independent translation. Together, our data uncover an essential role of deregulated snoRNA biogenesis in tumors and a new mechanism of nucleolar modulation of p53.

Repression of miR-126 and upregulation of adrenomedullin in the stromal endothelium by cancer-stromal cross talks confers angiogenesis of cervical cancer.

miR-126 is an endothelial-specific microRNA essential for maintaining vessel integrity during development. Its role of tumor angiogenesis in cancer stroma is unclear. This study investigated the temporal and spatial expression and the role of miR-126 in the course of cervical carcinogenesis. miR-126 was found to be mainly expressed in the stromal endothelium of the uterine cervix. This downregulation was recapitulated in a cell coculture model, wherein cross talk of cervical cancer cells and fibroblasts induced a downregulation of miR-126 in human umbilical vein endothelial cells, with consequent increase of tube formation. Coinjection of cancer-associated fibroblasts of human cervix enhanced tumorigenesis of cervical cancer cells, with an increase of microvessel density and dye retention in the tumor vasculature. In association with angiogenesis, host-originated miR-126 in these xenograft tumors was progressively downregulated, whereas supplement of the miR-126 precursor in the coinjection suppressed angiogenesis and tumor growth. A proangiogenic gene adrenomedullin (ADM), which was found to be upregulated in the stroma of cervical cancer and which localized mainly in the blood and lymphatic vessels, was identified as a target of inhibition by miR-126 at the carcinoma in situ-to-invasion stage. The study suggests a cancer stroma cross talk induced repression of miR-126 and upregulation of ADM, and probably other proangiogenic factors, to facilitate angiogenesis and invasion growth of cervical cancer.

The synergistic effects of fibroblast growth factor-2 and mineral trioxide aggregate on an osteogenic accelerator in vitro.

AIM: To examine the effects of mineral trioxide aggregate (MTA)/fibroblast growth factor-2 (FGF-2) on material properties and in vitro human dental pulp cell (hDPCs) behaviour. METHODOLOGY: The setting time and diametral tensile strength (DTS) of MTA and MTA/FGF-2 were measured. The structure of specimens before and after soaking in DMEM was examined under a scanning electron microscope. Alamar Blue was used for evaluating hDPCs proliferation. An enzyme-linked immunosorbent assay was employed to determine ALP and osteocalcin (OC) expression in hDPCs cultured on cements. The effect of small interfering RNA (siRNA) transfection targeting fibroblast growth factor receptor (FGFR) was also evaluated. One-way analysis of variance was used to evaluate the significance of the differences between the mean values. RESULTS: Setting time and DTS data were not found to be significant (P > 0.05) between MTA with and without FGF-2. Cell proliferation and differentiation increased significantly (P < 0.05) with FGF-2 mixed MTA. After siRNA transfection with FGFR, the proliferation and differentiation behaviour of the hDPCs appreciably decreased when cultured on an MTA/FGF-2 composite. In contrast, no significant amounts (P > 0.05) of ALP and OC were secreted by hDPCs seeded on MTA. CONCLUSIONS: Mineral trioxide aggregate with FGF-2 content enhanced the higher expression of hDPCs proliferation and osteogenic differentiation as compared to pure MTA cement.

Reversal of the Caspase-Dependent Apoptotic Cytotoxicity Pathway by Taurine from Lycium barbarum (Goji Berry) in Human Retinal Pigment Epithelial Cells: Potential Benefit in Diabetic Retinopathy.

Diabetic retinopathy is a preventable microvascular diabetic complication and a leading cause of vision loss. Retinal pigment epithelial cell apoptosis is an early event in diabetic retinopathy. Taurine is reportedly beneficial for diabetic retinopathy and is abundant in the fruit of Lycium barbarum (LB). We have investigated the effect of pure taurine and an extract of LB rich in taurine on a model of diabetic retinopathy, the retinal ARPE-19 cell line exposed to high glucose. We demonstrate for the first time that LB extract and the active ligand, taurine, dose dependently enhance cell viability following high glucose treatment in the ARPE-19 retinal epithelial cell line. This cytoprotective effect was associated with the attenuation of high glucose-induced apoptosis, which was shown by characteristic morphological staining and the dose-dependent decrease in the number of apoptotic cells, determined by flow cytometry. Moreover, we have shown that LB extract and taurine dose dependently downregulate caspase-3 protein expression and the enzymatic activity of caspase-3. We conclude that taurine, a major component of LB, and the LB extract, have a cytoprotective effect against glucose exposure in a human retinal epithelial cell line and may provide useful approaches to delaying diabetic retinopathy progression.

Lycium barbarum (Goji Berry) extracts and its taurine component inhibit PPAR-γ-dependent gene transcription in human retinal pigment epithelial cells: Possible implications for diabetic retinopathy treatment.

The peroxisome proliferator activated receptor-γ (PPAR-γ) is involved in the pathogenesis of diabetic retinopathy. Diabetic retinopathy is a preventable microvascular diabetic complication that damages human retinal pigment epithelial cells. Taurine is abundant in the fruit of Lycium barbarum (Goji Berry), and is reportedly beneficial for diabetic retinopathy. However, the mechanism of its action is unknown. Hence, we have investigated the mechanism of action of an extract from L. barbarum on a model of diabetic retinopathy, the retinal ARPE-19 cell line, and identified the receptor function of taurine, an active component of L. barbarum (Goji Berry) extract, which is potentially responsible for the protective effect on diabetic retinopathy. We demonstrate for the first time that L. barbarum extract and its taurine component dose-dependently enhance PPAR-γ luciferase activity in HEK293 cell line transfected with PPAR-γ reporter gene. This activity was significantly decreased by a selective PPAR-γ antagonist GW9662. Moreover, L. barbarum extract and taurine dose-dependently enhanced the expression of PPAR-γ mRNA and protein. In an inflammation model where ARPE-19 cells were exposed to high glucose L. barbarum extract and taurine down-regulated the mRNA of pro-inflammatory mediators encoding MMP-9, fibronectin and the protein expression of COX-2 and iNOS proteins. The predicted binding mode of taurine in the PPAR-γ ligand binding site mimics key electrostatic interactions seen with known PPAR-γ agonists. We conclude that PPAR-γ activation by L. barbarum extract is associated with its taurine content and may explain at least in part its use in diabetic retinopathy progression.

Methods for transcriptomic analyses of the porcine host immune response: application to Salmonella infection using microarrays.

Technological developments in both the collection and analysis of molecular genetic data over the past few years have provided new opportunities for an improved understanding of the global response to pathogen exposure. Such developments are particularly dramatic for scientists studying the pig, where tools to measure the expression of tens of thousands of transcripts, as well as unprecedented data on the porcine genome sequence, have combined to expand our abilities to elucidate the porcine immune system. In this review, we describe these recent developments in the context of our work using primarily microarrays to explore gene expression changes during infection of pigs by Salmonella. Thus while the focus is not a comprehensive review of all possible approaches, we provide links and information on both the tools we use as well as alternatives commonly available for transcriptomic data collection and analysis of porcine immune responses. Through this review, we expect readers will gain an appreciation for the necessary steps to plan, conduct, analyze and interpret the data from transcriptomic analyses directly applicable to their research interests.

Identification and characterization of microRNAs from porcine skeletal muscle.

MicroRNAs (miRNAs) are a class of non-coding RNAs that negatively regulate gene expression at the post-transcriptional level. There is increasing evidence to suggest that miRNAs participate in muscle development in mice and humans; however, few studies have focused on miRNAs in porcine muscle tissue. Here, we experimentally detected and identified conserved and unique miRNAs from porcine skeletal muscle. Fifty-seven distinct miRNAs were identified, of which 39 have not been reported earlier in the pig. Of these, two miRNAs appear to be novel and pig-specific. Surprisingly, these two differ only by a single nucleotide. A part of their primary transcript was cloned and confirmed by sequencing analysis. Alignment of the two sequences using ClustalW showed that the precursor sequences were almost identical, but the flanking sequences were different, indicating that these two novel miRNAs may represent rapidly evolving miRNAs in the pig genome. The expression patterns of eight miRNAs were characterized by real-time polymerase chain reaction of eight pig tissue samples. The ssc-let-7e and ssc-miR-181b miRNAs were expressed in all tissues analysed. The ssc-let-7c, ssc-miR-125b, ssc-miR-new1 and ssc-miR-new2 miRNAs were expressed in several tissues, while ssc-miR-122 and ssc-miR-206 were specifically expressed in the liver and muscle respectively. Our results add to existing data on porcine miRNAs and are useful for investigating the biological functions of miRNAs in porcine skeletal muscle development.

Water solution of onion crude powder inhibits RANKL-induced osteoclastogenesis through ERK, p38 and NF-kappaB pathways.

UNLABELLED: Onion powder has been reported to decrease the ovariectomy-induced bone resorption of rats. However, the molecular mechanism of onion powder on the bone cells has not been reported. Here, we report that water solution of onion crude powder decreases the osteoclastogenesis from co-cultures of bone marrow stromal cells and macrophage cells. Additionally, water solution of onion crude powder inhibits the RANKL-induced ERK, p38 and NF-kappaB activation in macrophages. In summary, our data showed that onion powder may benefit bone through an anti-resorption effect on the osteoclasts. INTRODUCTION: A nutritional approach is important for both prevention and treatment of osteoporosis. Onion has been reported to decrease the ovariectomy-induced bone resorption. However, the functional effects of onion on the cultured osteoclasts and osteoblasts remain largely unknown. Here, we found that water solution of onion crude powder markedly inhibited the receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclastogenesis through ERK, p38 and NF-kappaB pathways. Other studies were also designed to investigate the potential signaling pathways involved in onion-induced decrease in osteoclastogenesis. METHODS: The osteoclastogenesis was examined using the TRAP staining method. The MAPKs and NF-kappaB pathways were measured using Western blot analysis. A transfection protocol was used to examine NF-kappaB activity. RESULTS: Water solution of onion crude powder inhibited the RANKL plus M-CSF-induced osteoclastic differentiation from either bone marrow stromal cells or from RAW264.7 macrophage cells. Treatment of RAW264.7 macrophages with RANKL could induce the activation of ERK, p38 and NF-kappaB that was inhibited by water solution of onion crude powder. On the other hand, it did not affect the cell proliferation and differentiation of human cultured osteoblasts. CONCLUSIONS: Our data suggest that water solution of onion crude powder inhibits osteoclastogenesis from co-cultures of bone marrow stromal cells and macrophage cells via attenuation of RANKL-induced ERK, p38 and NF-kappaB activation.