MicroRNAs (miRs) are endogenously expressed 18–25-nucleotide RNAs that regulate gene expression through translational repression by binding to a target mRNA. Recently, it was indicated that miRs act as key regulators in cell differentiation, cell growth, and cell death. In osteogenesis, several miRs (for example miR-26a, -125b, -133, and -135) regulate osteoblast cell growth or differentiation in human adipose tissue-derived stem cells, mouse mesenchymal ST2 stem cells, and mouse premyogenic C2C12 cells. Additionally, Smad proteins control Drosha-mediated miR maturation. Therefore, miRs are closely related to osteogenesis. Here we investigated miR expression profile by an miR array and identified the candidate miRs, miR-141 and -200a, as pre-osteoblast differentiation-related miRs. The effects of miR-141 and -200a on pre-osteoblast differentiation were examined by using transfection of murine pre-osteoblastic MC3T3-E1 cells with mature miR-141 or -200a and antisense inhibitor for miR-141 or -200a. It was shown that miR-141 and -200a remarkably modulated the BMP-2-induced pre-osteoblast differentiation through the translational repression of Dlx5, which is a bone-generating transcription factor expressed in pre-osteoblast differentiation. Furthermore, it was indicated that Dlx5 is a common target of miR-141 and -200a by using a luciferase reporter assay. Thus, we have observed for the first time that miR-141 and -200a are involved in pre-osteoblast differentiation in part by regulating the expression of Dlx5.

This study aimed to examine the roles of reactive oxygen species (ROS) in cisplatin treatment of human prostate cancer cells; hormone-sensitive LNCaP and hormone-refractory PC3 and DU145 cells. Intracellular levels of ROS and H₂O₂ were measured and visualized using specific fluorescent probes. NADPH oxidase (NOX) activity was detected by lucigenin chemiluminescence assay. Expression levels of NOX isoforms were determined by semi-quantitative RT-PCR. Cisplatin treatment increased the intracellular levels of ROS and H₂O₂ in three prostate cancer cell lines. The increase was transient and robust in hormone-sensitive LNCaP cells compared with hormone-refractory PC3 and DU145 cells. Consistent with these findings, the NOX activity induced by cisplatin was higher in LNCaP cells than in PC3 and DU145 cells. Expression pattern of NOX isoforms varied among three cell lines and the NOX activity was independent of NOX expression. Taken together, we have shown that cisplatin induces production of ROS and H₂O₂ via NOX activation in human prostate cancer cell lines, which is most prominent in hormone-sensitive LNCaP cells.

MicroRNAs (miRs) represent a class of endogenous ∼18–25 nucleotide RNAs that regulate gene expression through translational repression by binding to a target mRNA. These miRs regulate several biological functions, such as cell growth, cell differentiation, carcinogenesis, and so on. In a previous report, we have indicated that miR-141 and -200a act as preosteoblast differentiation modulators. In the present study, using microRNA array and in silico analyses, we found that miR-208 is closely involved in preosteoblast differentiation by partially regulating the expression of Ets1 (V-ets erythroblastosis virus E26 oncogene homolog 1), which transactivates osteopontin, runt-related transcription factor 2, parathyroid hormone-related protein, and type I procollagen. Furthermore, the enforced expression of mature miR-208 in murine preosteoblast in MC3T3-E1 cells or primary osteoblast cells remarkably attenuated BMP-2-induced preosteoblast differentiation. In addition, we determined that Ets1 is a target gene of miR-208 by using a sensor luciferase reporter assay. Taken together, these results suggest that the down-regulation of miR-208 in BMP-2-stimulated osteoblast differentiation is an important part of the regulatory machinery involved in early osteogenesis.