mRNA Expression Levels Of Osteopontin Research Articles

Aging-associated increased nitric oxide production is a potential cause of inferior eggshell quality produced by aged laying hens

It is important to prolong the productive life of laying hens without compromising their welfare. Therefore, in this study, we aimed to identify the cause for inferior quality egg production of aged hens by investigating the aging-associated molecular changes related to eggshell formation in the isthmic and uterine mucosae and determining whether nitric oxide plays a role in decreasing the quality of eggs produced by aged hens. Young (35 weeks old) and aged (130 weeks old) White Leghorn laying hens were used in this study to determine the effects of age on the expression of proteins related to eggshell membranes formation in the isthmus and eggshell biomineralization and nitric oxide production in the uterus. Nitric oxide synthesis during the ovulatory cycle was examined in twenty-five laying hens (46–52 weeks old) euthanized at 0, 4, 7, 16, and 24 h after oviposition. S-Nitroso-N-acetylpenicillamine (a nitric oxide donor) was added to the cultured isthmic and uterine mucosal cells to examine the effects of nitric oxide on the expression of genes related to eggshell membranes formation and eggshell biomineralization, respectively. The results showed that the protein abundance of collagen I and V in the isthmic mucosa and collagen V in the eggshell membranes were lower in aged hens than in young hens. The mRNA expression levels of calbindin, osteopontin, and ovocalyxin-36 and the protein abundance of calbindin and carbonic anhydrase-2 were lower in the uterine mucosa of aged hens than in that of young hens. Nitric oxide synthesis was higher in the uterine mucosa of aged hens than in that of young hens. Nitric oxide downregulated the mRNA expression levels of osteopontin and ovocalyxin-36 in cultured uterine mucosal cells. Our results indicated that the eggshell quality decreases with aging due to molecular changes in the uterine mucosa affecting the eggshell membrane formation and eggshell biomineralization. Moreover, nitric oxide overproduction may play a role in this dysfunction.

Sperm osteopontin mRNA expression levels and its correlation on semen quality and fertility in Madura bulls

Abstract. Rosyada ZNA, Yoelinda VT, Kaiin EM, Gunawan M, Ulum MF, Tumbelaka LITA, Solihin DD, Agil M, Gunawan A, Purwantara B. 2023. Sperm osteopontin mRNA expression levels and its correlation on semen quality and fertility in Madura bulls. Biodiversitas 24: 563-570. Osteopontin (OPN) gene transcripts influence spermatogenesis and germ cell development. Therefore, transcriptome analysis is needed to identify the fertility factor OPN in Madura bull sperm. Madura cattle are crosses originating from Bos indicus (zebu) and Bos javanicus (banteng). This study aims to examine sperm osteopontin (OPN) mRNA expression levels and its correlation with semen quality and fertility in Madura bulls. Frozen semen samples from Madura bulls were categorized as high-fertile (n: 4, average field conception rate: 78.28±3.25%) or sub-fertile (n: 4, average field conception rate: 66.73±5.01%). In post-thaw semen samples, sperm motility, viability, membrane, acrosome, and DNA fragmentation index were evaluated. OPN expression in sperm total RNA was analyzed using Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR). The data analysis between the two fertility groups was assessed with Student's t-test and Pearson Square. Receiver-operating characteristic analysis and diagnostic sensitivity and specificity calculations were performed. Sperm motility, acrosome intact, and DFI differ (p<0.05) between groups, whereas viability and membrane plasma intact have no significance (p>0.05). In high-fertile Madura bulls, OPN mRNA was upregulated (p<0.05). The OPN mRNA expression had a strong correlation with the field conception rate (R: 0.807, P<0.05), sperm motility, and intact acrosome (R: 0.899, p<0.01; R: 0.804, p<0.05) respectively. In contrast, OPN negatively correlated with sperm DFI (R: -0.764, p<0.05). The OPN predicted bull fertility with 81.3% accuracy, 75% sensitivity, and 75% specificity. Thus, OPN may serve as a potential biomarker of Madura bull fertility.

Evaluation of local and circulating osteopontin in malignant and benign primary bone tumors

PurposeThe development of novel and efficient biomarkers for primary bone cancers is of grave importance. MethodsThe expression pattern of osteopontin (OPN) was investigated in the 153 patients with benign (n = 72) and malignant (n = 81) primary bone cancers. Both local and circulating OPN mRNA expression levels and their protein concentration in serum and tumor site were assessed using real-time qRT-PCR, ELISA, and immunohistochemistry techniques, respectively. As a control, 29 healthy individuals were considered. The number of 153 tumor tissue specimens and the 153 paired margins were taken on surgical resection from the patients. 153 blood samples were also drained from all participants, then peripheral blood mononuclear cells (PBMC) and sera were separated. ResultsThe mean mRNA expression was significantly higher in all of the cancerous tissues than the paired margins and the PBMC of the patients than the controls. Consistently, the protein concentrations of OPN in serum and tumor tissues were significantly higher in the patients. Furthermore, the malignant cases had significantly elevated the mRNA levels and the protein compared to the benign cases. OPN could potentially differentiate the patients from the controls with 100% sensitivity and specificity in serum. Moreover, OPN could predict some of the malignant cases' clinicopathological features, including metastasis, recurrence, grade, and response to chemotherapy. ConclusionsIn conclusion, OPN might be involved in the pathogenesis of primary bone tumors and can be considered as a potential biomarker to bone cancer diagnosis.

Investigation into the effects of leukemia inhibitory factor on the bone repair capacity of BMSCs-loaded BCP scaffolds in the mouse calvarial bone defect model.

Leukemia inhibitory factor (LIF) is known to play a major role in bone physiology. In the present study, we examined the in vitro effects of LIF on osteoblast differentiation of bone marrow stem cells (BMSCs) and explored in vivo effects of LIF on the bone repair capacity of BMSCs-loaded biphasic calcium phosphate (BCP) scaffolds in mouse calvarial bone defect model. The mRNA and protein expression levels in the BMSCs were determined by quantitative real-time PCR and western blot, respectively; the in vitro osteoblast differentiation of the BMSCs was evaluated by using Alizarin Red S staining. The bone volume and bone density in the repaired calvarial bone defect were determined by Micro-CT. Bone regeneration was also histologically evaluated by hematoxylin and eosin staining and Masson's trichrome staining. Hypoxia treatment induced the up-regulation of Lif mRNA and LIF protein in the BMSCs. Lif overexpression up-regulated the mRNA expression levels of osteopontin and Runt-related transcription factor 2, and increased intensity of Alizarin Red S staining in the BMSCs; while Lif silence exerted the opposite effects. The in vivo studies showed that implantation of Lif-overexpressing BMSCs-loaded BCP scaffolds significantly increased the bone volume and bone density at 4 and 8weeks after transplantation, and promoted the regeneration of bone tissues in the mouse calvarial bone defect at 8weeks after transplantation when compared to the BMSCs-loaded BCP scaffolds group; while Lif-silencing BMSCs-loaded BCP scaffolds had the opposite effects. The present study for the first time demonstrated that LIF promoted the in vitro osteoblast differentiation of hypoxia-treated BMSCs; and further studies revealed that LIF exerted enhanced effects on the bone repair capacity of BMSCs-load BCP scaffolds in mouse calvarial bone defect model. However, future studies are warranted to determine the detailed mechanisms of LIF in the large-scale bone defect repair.

Effect of ligand-receptor interaction of osteopontin-CD44 on the expression of hyaluronic acid in human knee osteoarthritic chondrocytes in vitro.

To investigate the effect of ligand-receptor interaction of osteopontin (OPN)-CD44 on the expression of hyaluronic acid (HA) in the cultured human knee osteoarthritis (OA) chondrocytes via interfering the reaction between OPN and CD44 ligand-receptor. The OA chondrocytes and normal chondrocytes were obtained from knee joint cartilage tissues in the patients with knee OA and malignant tumor respectively. The normal chondrocytes and OA chondrocytes were detected and analyzed, and then the intervention analysis of OA chondrocytes was carried out. The OA chondrocytes were divided into 4 groups: a negative control group, which was cultured with complete medium without any molecular intervention reagent; an OPN intervention group, which was cultured with recombinant human OPN (rhOPN) for 24 hours; a CD44 blocking group, which were pretreated with CD44 receptor specific antagonist for 1 hour to block the binding of OPN-CD44, and then treated with rhOPN for 23 hours; a CD44 homotype group, which was pretreated with CD44 for 1 hour and then treated with rhOPN for 23 hours. In addition, the study for OPN-CD44 axis was also divided into 4 groups: an OA-negative control group (OA-NC group), a si-OPN intervention group, a rhOPN intervention group, and a rhOPN + CD44 antibody (Ab) group. Western blotting, real-time PCR, and enzyme linked immunosorbent assay (ELISA) were used to detect the protein and mRNA expression levels of OPN, CD44, hyaluronate synthase (HAS), and HA, respectively. The protein expression levels of OPN, CD44, and HAS1 and the secretion levels of HA in the OA chondrocytes were higher than those in the normal chondrocytes. Compared with the OPN intervention group, the expression levels of HAS1, HAS2, HAS3 and HA in the CD44 blocking group were lower than those in OPN intervention group (all P<0.05); but there was no significant difference in the expression levels of HAS1, HAS2, HAS3 and HA between the CD44 homotype group and the OPN intervention group (all P>0.05). The results of OPN-CD44 axis study showed that: compared with the OA-NC group, the expression of CD44 in the rhOPN intervention group was slightly lower, but the protein and mRNA levels of HAS1 were significantly increased (all P<0.05); compared with the OA-NC group, the expression of CD44 was up-regulated, but the protein and mRNA level of HAS1 were significantly inhibited in the si-OPN intervention group (all P<0.05); compared with the OA-NC group, the protein and mRNA levels of HAS1 in the rhOPN+CD44 Ab group were also significantly inhibited (all P<0.05). The OPN in OA chondrocytes can promote the expression of HAS1, and the OPN can stimulate the secretion of HAS and induce HA expression by reacting with CD44 ligand receptor. They constitute the axis of OPN/CD44/HAS1, which plays an important role in regulating the expression of HA in chondrocytes.

Quercetin promotes MC3T3-E1 cell growth via PI3K/Akt signaling pathway

Purpose: To investigate the effect of quercetin on mouse osteoblast MC3T3-E1 cell growth and the molecular mechanisms involved.Methods: The effect of quercetin on MC3T3-E1 cells growth, cell cycle distribution, bone-related genes and PI3K/Akt signaling pathway were determined in vitro using MTT assay, flow cytometry, qPCR and western blot, respectively.Results: Qercetin promoted MC3T3-E1 cell growth, as revealed from MTT assay. Flow cytometryshowed that quercetin administration resulted in accumulation of cells in the S phase. In addition, quercetin up-regulated mRNA expression levels of osteopontin, ALP, osteoprotegerin, osteocalcin and RunX-2, and increased phosphorylation of AKT.Conclusion: Quercetin enhances the growth of MC3T3-E1 cells via a mechanism involving accumulation of cells in S phase, increasing mRNA expression levels of bone-associated genes, and increasing the phosphorylation of AKT.Keywords: Quercetin, MC3T3-E1 cells, AKT phosphorylation, Osteopontin, Osteoprotegerin, Osteocalcin, RunX-2

Expression of Osteopontin mRNA During Periodontal Healing Following Scaling and Root Planing

Objective: To analyze osteopontin mRNA expression levels in subjects with periodontitis prior to (baseline) and 7, 14, and 28 days following scaling and root planing (SRP). Material and Methods: Gingival crevicular fluid was collected as clinical samples from four subjects with periodontitis (pocket depth, 4 - 5 mm) aged 35 - 54 years old as well as from three healthy subjects (controls). The osteopontin mRNA expression levels were measured by quantitative real-time polymerase chain reaction. Spearman’s rank correlation between osteopontin levels in gingival crevicular fluid and the modified gingival index (MGI) was also performed. Results: The Wilcoxon signed-rank test showed no significant difference in osteopontin mRNA expression levels between baseline and 28 days following SRP (p=0.068). The Friedman test showed no significant difference in osteopontin mRNA expression levels between baseline and following SRP (7, 14, or 28 days) (p>0.05). Spearman’s rank correlation showed no significant correlation between osteopontin mRNA expression levels and MGI (r=0.087; p=0.749). Conclusion: Following SRP of periodontal tissue, there was a decreasing trend in osteopontin mRNA expression; however, this finding was not statistically significant. Nevertheless, osteopontin can be used as a biomarker to monitor the healing process; however, further studies are required to clarify our results.

Comparison of the osteogenic differentiation of orofacial bone marrow stromal cells prior to and following marsupialization in patients with odontogenic cyst.

Decompression has been considered a valuable tool for odontogenic cystic lesions to minimize cyst size with low morbidity and recurrence. However, whether decompression has a role in regulating stem cell properties of orofacial bone marrow stromal cells (BMSCs) around the cysts has not been fully investigated. The present study compared the stem cell marker profile and osteogenic differentiation potential of orofacial BMSCs prior to and following marsupialization (pre-BMSCs vs. post-BMSCs) in the same individuals. The results demonstrated that post-BMSCs proliferated significantly faster, displayed higher colony-forming unit-fibroblast capacity and demonstrated higher expression of octamer binding protein 4, Nanog and SRY-related HMG box 2 when compared with the pre-BMSCs. Notably, the osteogenic potential was greater in the post-BMSCs compared with in pre-BMSCs, by demonstrating that the protein and mRNA expression levels of osteopontin, runt-related transcription factor 2, osteocalcin, alkaline phosphatase and osterix were upregulated in pre-BMSCs. Furthermore, the phosphorylated levels of extracellular signal-regulated kinase and c-Jun N-terminal kinase were enhanced in post-BMSCs. In conclusion, the study indicated that decompression influences the stem cell properties of orofacial BMSCs, and further studies are needed to verify the findings.

Age-associated and tissue-specific expression of osteopontin in male Hu sheep reproductive tract.

Osteopontin (OPN) is indispensable in mammalian reproduction, but the role of OPN in male reproductive tract and fertility remains unclear. The objective of this study is to elucidate the function of OPN by unveiling the localization and expression of OPN in the reproductive tract (testis, epididymis, and ductus deferens) of male Hu sheep in different ages (10-days, 4-months, and 8-months). To accomplish this, the localization, mRNA and protein expression patterns of OPN in all samples were investigated. Immune staining showed that OPN was present in the testicular interstitium of prepubertal Hu sheep testis (10-days and 4-months group), while it was immunostained in acrosomes of spermatids nearby adluminal compartment of seminiferous tubules in sexual maturity Hu sheep testis (8-months group). The localization of OPN in epididymis gradually changed from the loose connective tissue to the apical region of principal cells (pseudostratified columnar epithelium) with growing (10-days to 8-months). In addition, increase trend was observed in the mRNA expression levels of OPN with growing in the same reproductive tissues (P<0.05). Furthermore, two different OPN isoforms of 30kDa and 34kDa were detected in the reproductive tract of male Hu sheep by western blot. Immunofluorescence detection showed that OPN was localized in the cauda epididymal spermatozoa. These results suggested that the expression of OPN might be closely related to spermatogenesis and spermatozoa function in Hu sheep. This will be helpful for us to understand how OPN regulate the high reproductive capacity in Hu sheep.

Osteopontin inhibits HIF-2α mRNA expression in osteoarthritic chondrocytes.

The aim of the present study was to investigate the in vitro effect of osteopontin (OPN) on the expression of hypoxia-inducible factor-2α (HIF-2α) in chondrocytes and the role of OPN in osteoarthritis (OA). Cartilage was purified from the tibial surfaces of patients with OA of the knee and cultured in vitro to obtain chondrocytes. Recombinant human OPN (rhOPN) and OPN small interfering RNA (siRNA) were used to treat the chondrocytes, and the changes in the expression levels of the HIF-2α gene were measured. An anti-CD44 blocking monoclonal antibody (mAb) was used to determine the probable ligand-receptor interactions. Reverse transcription-quantitative polymerase chain reaction assays were designed and validated with SYBR® Green dyes for the simultaneous quantification of the mRNA expression levels of OPN and HIF-2α. The mRNA expression level of HIF-2α was markedly decreased in the rhOPN-treated group compared with that in the control group; by contrast, OPN siRNA increased HIF-2α gene expression. CD44 blocking mAb suppressed the inhibitory effect of OPN on HIF-2α mRNA expression. The results of the present study suggest that OPN may play a protective role in OA by inhibiting HIF-2α gene expression in osteoarthritic chondrocytes through CD44 interaction.

Effects of pulsed 2.856 GHz microwave exposure on BM-MSCs isolated from C57BL/6 mice.

The increasing use of microwave devices over recent years has meant the bioeffects of microwave exposure have been widely investigated and reported. However the exact biological fate of bone marrow MSCs (BM-MSCs) after microwave radiation remains unknown. In this study, the potential cytotoxicity on MSC proliferation, apoptosis, cell cycle, and in vitro differentiation were assayed following 2.856 GHz microwave exposure at a specific absorption rate (SAR) of 4 W/kg. Importantly, our findings indicated no significant changes in cell viability, cell division and apoptosis after microwave treatment. Furthermore, we detected no significant effects on the differentiation ability of these cells in vitro, with the exception of reduction in mRNA expression levels of osteopontin (OPN) and osteocalcin (OCN). These findings suggest that microwave treatment at a SAR of 4 W/kg has undefined adverse effects on BM-MSCs. However, the reduced-expression of proteins related to osteogenic differentiation suggests that microwave can the influence at the mRNA expression genetic level.

Osteopontin Gene Expression is Inversely Regulate 5-Fluorouracil Drug Resistance in Colon Cancer

Background: Resistance to chemotherapeutic drugs complicates the treatment of cancer patients. The extracellular matrix protein osteopontin (OPN) plays multiple roles in the proliferation and metastasis of cancer cells. We therefore attempted to determine whether OPN expression correlated with drug resistance. Methods: OPN expression in the HCT 116 colon cancer cell line was inhibited by an OPN-short interfering RNA (siRNA). We determined the cytotoxic effect (IC50) of 5-fluorouracil (5FU) on these cells. Patients with recurrence or colorectal cancer or harbored residual tumor cells were treated with S-1-based chemotherapy. The levels of OPN mRNA expression in the tumors were determined and compared with the patients’ responses to chemotherapy. Results: The IC50 of 5FU for HCT 116 cells transfected with the OPN-siRNA was 32.9 μM. In contrast, the IC50 values for cells transfected with a negative control siRNA, mock-transfected cells, or untreated cells were 6.58 μM, 7.08 μM, and 6.76 μM, respectively (P<0.001). The level of OPN mRNA expression in the S-1 non-responder group was significantly lower than that of the responder group (P = 0.0387). Survival analysis revealed no significant difference between the responder and non-responder groups (P = 0.8737). Conclusions: The level of OPN expression plays a role in the resistance of colorectal tumor cells to 5FU.

Abstract 779: Osteopontin gene expression is associated with 5-fluorouracil drug resistance in colon cancer

Abstract Background: Resistance to chemotherapeutic drugs complicates the treatment of cancer patients. The extracellular matrix protein osteopontin (OPN) plays multiple roles in the proliferation and metastasis of cancer cells. We therefore attempted to determine whether OPN expression correlated with drug resistance. Methods: OPN expression in the HCT 116 colon cancer cell line was inhibited by an OPN-short interfering RNA (siRNA). We determined the cytotoxic effect (IC50) of 5-fluorouracil (5FU) on these cells. Patients with recurrence or colorectal cancer or harbored residual tumor cells were treated with S-1-based chemotherapy. The levels of OPN mRNA expression in the tumors were determined and compared with the patients’ responses to chemotherapy. Results: The IC50 of 5FU for HCT 116 cells transfected with the OPN-siRNA was 32.9 μM. In contrast, the IC50 values for cells transfected with a negative control siRNA, mock-transfected cells, or untreated cells were 6.58 μM, 7.08 μM, and 6.76 μM, respectively (P&amp;lt;0.001). The level of OPN mRNA expression in the S-1 non-responder group was significantly lower than that of the responder group (P = 0.0387). Survival analysis revealed no significant difference between the responder and non-responder groups (P = 0.8737). Conclusions: The level of OPN expression plays a role in the resistance of colorectal tumor cells to 5FU. Citation Format: Go Nakajima, Hidekazu Kuramochi, Masakazu Yamamoto, Kazuhiko Hayashi. Osteopontin gene expression is associated with 5-fluorouracil drug resistance in colon cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 779. doi:10.1158/1538-7445.AM2014-779

Osteopontin knockdown suppresses the growth and angiogenesis of colon cancer cells.

To investigate the effects of osteopontin (OPN) gene expression knockdown on colon cancer Lovo cells in vitro. Four candidate small interfering RNA (siRNA) constructs targeting the OPN gene and a scrambled control sequence (NC-siRNA) were synthesized and inserted into a pGPU6/GFP/Neo expression vector. After confirmation by restriction enzyme digestion and DNA sequencing, the recombinant plasmids were subsequently transfected into a human colon cancer cell line (Lovo) using a liposome transfection method. Stably transfected cells were maintained with G418 selection and referred to as Lovo-OPN-1, -2, -3, -4, and Lovo-NC cells. Knockdown efficiency of each of the four siRNA constructs was determined by real-time reverse transcription polymerase chain reaction assays and western blotting, and the construct with the most effective silencing was used for subsequent experiments. Cell proliferation, adhesion, and Matrigel invasion assays were performed to analyze the effects of OPN knockdown in stably transfected Lovo cells. The levels of four angiogenic factors, namely vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, MMP-9 and urokinase plasminogen activator were detected by enzyme-linked immunosorbent assays (ELISA). Recombinant vectors containing OPN-specific and scrambled siRNA sequences were successfully constructed and stably transfected into Lovo cells. Compared with the control Lovo and Lovo-NC cells, the levels of OPN mRNA and protein expression in Lovo-OPN-1, -2, -3, and -4 were significantly reduced (all P < 0.05), with the most efficient reduction observed in Lovo-OPN-4 cells (P < 0.05). Relative to untransfected Lovo cells, OPN mRNA expression levels in Lovo-NC and Lovo-OPN-4 cells were 1.008 ± 0.067 and 0.160 ± 0.023, respectively. The relative OPN protein expression levels in Lovo, Lovo-NC, and Lovo-OPN-4 cells were 3.024 ± 0.211, 2.974 ± 0.630, and 0.121 ± 0.008, respectively. Moreover, transfection with the scrambled sequence had no effect on the expression of OPN. After 24, 48, 72, and 96 h of cultivation, absorption values at 450 nm to assess proliferation of Lovo-OPN-4 cells were 0.210 ± 0.017, 0.247 ± 0.024, 0.314 ± 0.037, and 0.359 ± 0.043, respectively, which were significantly lower than those of Lovo (0.244 ± 0.031, 0.313 ± 0.024, 0.513 ± 0.048 and 0.783 ± 0.051) and Lovo-NC cells (0.241 ± 0.029, 0.309 ± 0.022, 0.563 ± 0.023, and 0.735 ± 0.067) (all P < 0.05). The absorption values at 595 nm, which were measured in a cell adhesion assay, showed that adhesion of Lovo-OPN-4 cells (0.215 ± 0.036) was significantly decreased compared to Lovo (0.490 ± 0.037) and Lovo-NC cells (0.462 ± 0.043) (P < 0.05). The number of invasive Lovo-OPN-4 cells (16.1 ± 1.9) was also significantly decreased compared to Lovo (49.9 ± 5.4) and Lovo-NC cells (48.8 ± 4.5) (P < 0.05). ELISA assays showed significant reductions in Lovo-OPN-4 cells compared to Lovo and Lovo-NC cells with regard to the expression of VEGF (1687.85 ± 167.84 ng/L vs 2348.54 ± 143.80 ng/L and 2284.39 ± 138.62 ng/L, respectively), MMP-2 (2966.07 ± 177.36 μg/L vs 4084.74 ± 349.54 μg/L and 4011.41 ± 424.48 μg/L, respectively), MMP-9 (3782.89 ± 300.64 μg/L vs 5062.90 ± 303.02 μg/L and 4986.38 ± 300.75 μg/L, respectively) and uPA (1152.69 ± 120.79 μg/L vs 1380.90 ± 147.25 μg/L and 1449.80 ± 189.92 μg/L, respectively) (all P < 0.05). Knockdown of OPN gene expression suppresses colon cancer cell growth, adherence, invasion, and expression of angiogenic factors.

Proximal renal tubular injury in rats sub-chronically exposed to low fluoride concentrations

Fluoride is usually found in groundwater at a very wide range of concentration between 0.5 and 25ppm. At present, few studies have assessed the renal effects of fluoride at environmentally relevant concentrations. Furthermore, most of these studies have used insensitive and nonspecific biomarkers of kidney injury. The aim of this study was to use early and sensitive biomarkers to evaluate kidney injury after fluoride exposure to environmentally relevant concentrations. Recently weaned male Wistar rats were exposed to low (15ppm) and high (50ppm) fluoride concentrations in drinking water for a period of 40days. At the end of the exposure period, kidney injury biomarkers were measured in urine and renal mRNA expression levels were assessed by real time RT-PCR. Our results showed that the urinary kidney injury molecule (Kim-1), clusterin (Clu), osteopontin (OPN) and heat shock protein 72 excretion rate significantly increased in the group exposed to the high fluoride concentration. Accordingly, fluoride exposure increased renal Kim-1, Clu and OPN mRNA expression levels. Moreover, there was a significant dose-dependent increase in urinary β-2-microglobulin and cystatin-C excretion rate. Additionally, a tendency towards a dose dependent increase of tubular damage in the histopathological light microscopy findings confirmed the preferential impact of fluoride on the tubular structure. All of these changes occurred at early stages in which, the renal function was not altered. In conclusion using early and sensitive biomarkers of kidney injury, we were able to found proximal tubular alterations in rats sub-chronically exposed to fluoride.

A mutant of hepatitis B virus X protein (HBxΔ127) enhances hepatoma cell migration via osteopontin involving 5-lipoxygenase

To explore a novel function of a mutant of the hepatitis B virus X protein (HBx Delta 127) in the promotion of hepatoma cell migration. The effect of HBx Delta 127 and wild type HBx on the migration ability of hepatoblastoma HepG2 cells were examined using wound healing assays in stable transfection systems. The full-length osteopontin(OPN) promoter sequence was cloned into the pGL3-Basic plasmid. The promoter activities of OPN in stably HBx Delta 127-transfected hepatoblastoma HepG2 (HepG2-X Delta 127) and hepatocellular carcinoma H7402 (H7402-X Delta 127) cells were determined using luciferase reporter gene assays. The mRNA expression levels of OPN were detected by RT-PCR. And the effect of MK886, a specific inhibitor of 5-lipoxygenase (5-LOX), on OPN promoter activity and mRNA expression in HepG2-X Delta 127 and H7402-X Delta 127 cells were examined using luciferase reporter gene assays and RT-PCR, respectively. Finally, the migration ability of HepG2-X Delta 127 was observed after treatment with siRNA targeting OPN mRNA and HBx mRNA using wound healing assays. HepG2-X Delta 127 cells exhibited a greater capacity for wound repair compared to HepG2-X cells. The promoter activity and mRNA expression levels of OPN were also increased in HepG2-X Delta 127 and H7402-X Delta 127 cells. Moreover, MK886 abolished the HBx Delta 127-mediated upregulation of OPN. Wound healing assays demonstrated that the migration ability of HepG2-X Delta 127 cells can be suppressed by treatment with siRNA targeting OPN mRNA and siRNA targeting HBx mRNA. HBx Delta 127 strongly promotes hepatoma cell migration via activation of OPN involving 5-LOX.

Initial effects of low-level laser therapy on growth and differentiation of human osteoblast-like cells

Low-level laser therapy is a clinically well established tool for enhancement of wound healing. In vitro studies have also shown that low level laser therapy has a biostimulatory effect on cells of different origin. The aim of this in vitro study was to investigate the initial effect of low-level laser therapy on growth and differentiation of human osteoblast-like cells. SaOS-2 cells were irradiated with laser doses of 1 J/cm2 and 2 J/cm2 using a diode laser with 670 nm wave length and an output power of 400 mW. Untreated cells were used as controls. At 24 h, 48 h and 72 h post irradiation, cells were collected and assayed for viability of attached cells and alkaline phosphatase specific activity. In addition, mRNA expression levels of osteopontin and collagen type I were assessed using semi-quantitative RT-PCR. Over the observation period, cell viability, alkaline phosphatase activity and the expression of osteopontin and collagen type I mRNA were slightly enhanced in cells irradiated with 1 J/cm2 compared with untreated control cells. Increasing the laser dose to 2 J/cm2 reduced cell viability during the first 48 h and resulted in persistently lower alkaline phosphatase activity compared with the other two groups. The expression of osteopontin and collagen type I mRNA slightly decreased with time in untreated controls and cells irradiated with 1 J/cm2, but their expression was increased by treatment with 2 J/cm2 after 72 h. These results indicate that low-level laser therapy has a biostimulatory effect on human osteoblast-like cells during the first 72 h after irradiation. Further studies are needed to determine the potential of low-level laser therapy as new treatment concept in bone regeneration.

Osteopontin Expression Correlates with Melanoma Invasion

Melanoma is one of the most aggressive cancers affecting humans. Although early melanomas are curable with surgical excision, metastatic melanomas are associated with high mortality. The mechanism of melanoma development, progression, and metastasis is largely unknown. In order to uncover genes unique to melanoma cells, we used high-density DNA microarrays to examine the gene expression profiles of metastatic melanoma nodules using benign nevi as controls. Over 190 genes were significantly overexpressed in metastatic melanomas compared with normal nevi by at least 2-fold. One of the most abundantly expressed genes in metastatic melanoma nodules is osteopontin (OPN). Immunohistochemistry staining on tissue microarrays and individual skin biopsies representing different stages of melanoma progression revealed that OPN expression is first acquired at the step of melanoma tissue invasion. In addition, blocking of OPN expression by RNA interference reduced melanoma cell numbers in vitro. Our observations suggest that OPN may be acquired early in melanoma development and progression, and may enhance tumor cell growth in invasive melanoma.

Upregulation of osteopontin expression in rat spinal cord microglia after traumatic injury.

Osteopontin is a noncollagenous extracellular matrix protein that is expressed in various tissues. Recent studies have shown the upregulation of osteopontin expression in the ischemic cortex after cerebral infarction. We demonstrate here the upregulation of osteopontin expression in the spinal cord after compression injury. Laboratory rats were used in a compression model of spinal cord injury (30-g load for 5 min). Northern blot analysis showed that osteopontin mRNA expression levels reached a peak 3 days after injury (sevenfold; p < 0.05). In situ hybridization demonstrated osteopontin mRNA expression in necrotic areas from 24 h, peaking 3 days after injury. Immunohistochemistry detected osteopontin protein immunoreactivity from 12 h, peaking at 3 days. The peak time and distribution of osteopontin protein expression were coincident with those of osteopontin mRNA expression. Osteopontin expression in our model preceded that shown in the previously reported cerebral infarction models. Osteopontin protein was found in the cytoplasm at 3 days and secreted into the extracellular matrix at 7 days. Triple immunolabeling showed that osteopontin was localized in activated microglia surrounded by astrocytes.

Osteopontin Gene Regulation by Oscillatory Fluid Flow via Intracellular Calcium Mobilization and Activation of Mitogen-activated Protein Kinase in MC3T3–E1 Osteoblasts

Recently fluid flow has been shown to be a potent physical stimulus in the regulation of bone cell metabolism. However, most investigators have applied steady or pulsing flow profiles rather than oscillatory fluid flow, which occurs in vivo because of mechanical loading. Here oscillatory fluid flow was demonstrated to be a potentially important physical signal for loading-induced changes in bone cell metabolism. We selected three well known biological response variables including intracellular calcium (Ca(2+)i), mitogen-activated protein kinase (MAPK) activity, and osteopontin (OPN) mRNA levels to examine the response of MC3T3-E1 osteoblastic cells to oscillatory fluid flow with shear stresses ranging from 2 to -2 Newtons/m(2) at 1 Hz, which is in the range expected to occur during routine physical activities. Our results showed that within 1 min, oscillatory flow induced cell Ca(2+)i mobilization, whereas two MAPKs (ERK and p38) were activated over a 2-h time frame. However, there was no activation of JNK. Furthermore 2 h of oscillatory fluid flow increased steady-state OPN mRNA expression levels by approximately 4-fold, 24 h after exposure to fluid flow. The presence of both ERK and p38 inhibitors and thapsigargin completely abolished the effect of oscillatory flow on steady-state OPN mRNA levels. In addition, experiments using a variety of pharmacological agents suggest that oscillatory flow induces Ca(2+)i mobilization via the L-type voltage-operated calcium channel and the inositol 1,4,5-trisphosphate pathway.