LncRNA MEG3 inhibits proliferation and promotes apoptosis of osteosarcoma cells through regulating Notch signaling pathway.

OBJECTIVE: To explore the effect of long non-coding ribonucleic acid (lncRNA)-maternally expressed gene 3 (MEG3) on the Notch signaling pathway, and its influences on the proliferation and apoptosis of osteosarcoma MG-63 cells. MATERIALS AND METHODS: LncRNA MEG3 was overexpressed in osteosarcoma MG-63 cells, and the cells were divided into Blank group, Len-con group, and Len-MEG3 group. The expression level of MEG3 in each group was detected via quantitative Polymerase Chain Reaction (qPCR), the cell proliferation level in each group was detected via Cell Counting Kit-8 (CCK-8) assay, and the apoptosis in each group was detected via Hoechst 33258 staining. Moreover, the content of the inflammatory factors in each group was determined using the Enzyme-Linked Immunosorbent Assay (ELISA), and the expression levels of apoptosis-related proteins and Notch signaling pathway-related proteins were determined through Western blotting. RESULTS: The expression level of lncRNA MEG3 in Len-MEG3 group was significantly higher than that in the Blank group and Len-con group (p<0.01). The overexpression of lncRNA MEG3 could significantly weaken the proliferation (p<0.01) and enhance the apoptosis of osteosarcoma cells (p<0.01). The overexpression of lncRNA MEG3 could significantly increase the content of the inflammatory factor interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) (p<0.01), and remarkably decrease the content of the anti-inflammatory factor IL-10 in osteosarcoma cells (p<0.01). Besides, the overexpression of lncRNA MEG3 could evidently raise the expression of Caspase3 (p<0.01) and reduce the Bcl-2/Bax expression in osteosarcoma cells (p<0.01). Finally, the overexpression of lncRNA MEG3 could remarkably reduce the protein expressions of Jagged1, Notch1, and NICD1 in osteosarcoma cells (p<0.01). CONCLUSIONS: The overexpression of lncRNA MEG3 can inhibit the proliferation and promote the apoptosis of osteosarcoma MG-63 cells by suppressing the Notch signaling pathway.

Novel Human Three-Domain Antibody Fragments Against sTNFα as Well as tmTNFα with High Affinity Generated by the Combination of Ribosome Display and E. coli Expression System.

Human tumour necrosis factor α (hTNFα) has been proved to be a validated therapeutic target in a number of immune-mediated inflammatory diseases (IMIDs). Fully human monoclonal antibodies (mAbs) that can neutralize soluble hTNFα (sTNFα) as well as transmembrane hTNFα (tmTNFα) are more desirable hTNFα antagonists. Here, we report that novel anti-hTNFα human low-molecular-weight MAbs have been selected and identified using both sTNFα and tmTNFα as target antigens by the combination of ribosome display and E. coli expression system for the first time. As a newly born engineering small molecular antibody, three-domain antibody fragment (VH /κ) provides an alternative promising molecular principle to generate biological agents for TNFα-dependent IMIDs. In this study, a panel of novel human VH /κs (F09, F21, F49 and F409) with high affinity (10(-10) -10(-9) mol/l) to neutralize sTNFα as well as tmTNFα was generated by the combination of ribosome display and E. coli expression system. Among the four clones, F21 and F409 could reduce cytotoxicity on L929 cells induced by sTNFα as well as tmTNFα effectively, and both of them had great potential to inhibit hTNFα-mediated NF-κB activation. Soluble F21 and F409 were also able to inhibit the binding of hTNFα to TNFR1 and TNFR2. The new human antibodies described here have desirable capability to neutralize sTNFα as well as tmTNFα effectively with high affinity and reasonable stability; this may provide an alternative approach for patients who are not responding adequately to currently available anti-TNFα agents.