The Subcellular Localization of IncRNA FAM230B in Osteosarcoma and Its Interaction with Early miR-203.

Previous studies have revealed the role of lncRNA FAM230B in promoting papillary thyroid cancer and gastric cancer. We predicted that FAM230B may interact with miR-203 and studied the crosstalk between FAM230B and miR-203 in osteosarcoma (OS). Paired OS and nontumor tissues donated by 60 patients with OS were subjected to RNA isolations and quantitative real-time PCR (RT-qPCR) to analyze the expression of both FAM230B and miR-203 (mature and premature levels). Subcellular location of FAM230B in OS cells was detected using subcellular fractionation assay. RNA pull-down assay was performed to investigate the direct interaction between FAM230B and miR-203. Overexpression assays followed by RT-qPCR were performed to analyze the role of FAM230B in miR-203 maturation. Cell proliferation was studied with 5-Bromo-2-deoxyUridine (BrdU) assay. FAM230B and premature miR-203 were upregulated in OS, whereas mature miR-203 was downregulated in OS cells. FAM230B was detected in the cytoplasm and directly interacted with premature miR-203. FAM230B overexpression in OS cells increased premature miR-203 level and decreased mature miR-203 level. FAM230B increased cell proliferation and suppressed the role of miR-203 in inhibiting cell proliferation. FAM230B in the cytoplasm may sponge premature miR-203, thereby inhibiting miR-203 maturation to increase OS cell proliferation.

MicroRNA-492 overexpression exerts suppressive effects on the progression of osteosarcoma by targeting PAK7.

MicroRNAs (miRNAs or miRs), which are a class of non-coding RNAs, have emerged as effective modulators of various aspects of biological processes. Accumulating evidence has established significant associations between the dysregulation of miRs and tumorigenesis in various types of cancer. However, the role of miR­492, particularly in osteosarcoma (OS) remains elusive. In present study, we demonstrated that miR­492 functions as putative tumor suppressor miR in OS. The level of miR­492 was frequently downregulated in both OS tissues and cell lines. Moreover, the ectopic overexpression of miR­492 effectively inhibited the proliferation, migration and invasion of OS cell lines. Furthermore, transfection with a miR­492 overexpression vector also strongly attenuated the growth of xenograft tumors in vivo. p21-activated kinase (PAK7) was identified as the putative target of miR­492 in OS, and we further found a significantly inverse correlation between PAK7 and miR­492 in OS specimens. Taken together, our study has unraveled a novel role for miR­492 in OS and may help in establishing the rationale for more effective treatment strategies for OS via miR regulation.

Beneficial effects of coculturing synovial derived mesenchymal stem cells with meniscus fibrochondrocytes are mediated by fibroblast growth factor 1: increased proliferation and collagen synthesis.

Meniscus reconstruction is in great need for orthopedic surgeons. Meniscal fibrochondrocytes transplantation was proposed to regenerate functional meniscus, with limited donor supply. We hypothesized that coculture of synovial mesenchymal stem cells (SSC) with meniscal fibrochondrocytes (me-CH) can support matrix production of me-CH, thus reducing the number of me-CH needed for meniscus reconstruction. A pellet coculture system of human SSC and me-CH was used in this study. Enhanced glycosaminoglycans (GAG) in coculture pellets were demonstrated by Alcian blue staining and GAG quantification, when compared to monoculture. More collagen synthesis was shown in coculture pellets by hydroxyproline assay. Increased proliferation of me-CH was observed in coculture. Data from BrdU staining and ELISA demonstrated that conditioned medium of SSCs enhanced the proliferation and collagen synthesis of me-CH, and this effect was blocked by neutralizing antibody against fibroblast growth factor 1 (FGF1). Western blot showed that conditioned medium of SSCs can activate mitogen-activated protein kinase (MAPK) signaling pathways by increasing the phosphorylation of mitogen-activated regulated protein kinase 1/2 (MEK) and extracellular-signal-regulated kinases 1/2 (ERK). Overall, this study provided evidence that synovial MSCs can support proliferation and collagen synthesis of fibrochondrocytes, by secreting FGF1. Coimplantation of SSC and me-CH could be a useful strategy for reconstructing meniscus.

GDC-0152 attenuates the malignant progression of osteosarcoma promoted by ANGPTL2 via PI3K/AKT but not p38MAPK signaling pathway.

Angiopoietin-like protein 2 (ANGPTL2) plays an important role in inflammatory carcinogenesis and tumor metastasis. The compound GDC-0152 is a peptidomimetic small molecule antagonist of inhibitor of apoptosis (IAP) proteins with antitumor activity. However, the interaction between ANGPTL2 and GDC-0152 has not been studied. It has been proven that ANGPTL2 promotes metastasis of osteosarcoma. Therefore, in the present study, the effect of GDC-0152 on the malignant progression of osteosarcoma promoted by ANGPTL2 was investigated. Human osteosarcoma cell line SaOS2 cells were pre-treated or non-treated with GDC-0152 and then exposed to recombinant human ANGPTL2. The viability of SaOS2 cells was determined by MTT assay, the migration of SaOS2 cells was analyzed by chamber migration assay kit, and the SaOS2 cell apoptosis was determined by fluorescence-activated cell sorting (FACS) and nuclear staining. Treatment with ANGPTL2 increased SaOS2 cell growth and migration and decreased cell apoptosis. The increased cell growth and decreased cell apoptosis were significantly attenuated in SaOS2 cells receiving GDC-0152. However, the ANGPTL2-increased SaOS2 cell migration was not inhibited by GDC-0152 treatment. Furthermore, western blot analysis showed that the activation of phosphatidyl inositol 3-kinase (PI3K) (p85), PI3K (p110), protein kinase B (Akt) (Ser473), Akt (Thr308) and p38 mitogen-activated protein kinase (p38MAPK) were upregulated by ANGPTL2. Quantitative real-time polymerase chain reaction (qTR-PCR) and gelatin zymography showed that the mRNA expression and activity of matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase-2 (MMP-2) were also increased by ANGPTL2. The upregulated activation of PI3K and Akt were significantly suppressed by the treatment of GDC-0152. In contrast, GDC-0152 did not suppress ANGPTL2-induced p38MAPK phosphorylation, MMP-9/MMP-2 mRNA expression or MMP-9/MMP-2 activity. Taken together, these data indicate that GDC-0152 attenuates the malignant progression of osteosarcoma promoted by ANGPTL2 via PI3K/AKT but not p38MAPK signaling pathway. The present study indicated a novel therapeutic strategy to inhibit tumor growth by indirectly preventing ANGPTL2 signaling.