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Aim The co-expression network of long non-coding RNA ROR (lncRNA-ROR) and microRNA-185-3p (miR-185-3p) has not been focused on osteosarcoma. Therein, this work was initiated to uncover lncRNA-ROR and miR-185-3p functions in osteosarcoma. Methods LncRNA-ROR, miR-185-3p and Yes-associated protein 1 (YAP1) expression in osteosarcoma tissues and cells were detected. The screened cells (MG63 and U2OS) were transfected with decreased and/or increased lncRNA-ROR and miR-185-3p to explore osteosarcoma progression. Tumor growth was detected by tumor xenografts in mice. Results Up-regulated lncRNA-ROR and YAP1 and down-regulated miR-185-3p were found in osteosarcoma. LncRNA ROR knockdown or miR-185-3p overexpression inhibited osteosarcoma cell progression while lncRNA ROR elevation or miR-185-3p inhibition presented the opposite effects. Function of lncRNA ROR was rescued by miR-185-3p and regulated the growth and metastasis of osteosarcoma cells via modulating YAP1, the target gene of miR-185-3p. Conclusion This work illustrates that lncRNA-ROR down-regulation or miR-185-3p up-regulation inhibits osteosarcoma progression via YAP1 repression.

The switch between osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) plays a key role in aging-induced osteoporosis. In this study, miR-19a-3p was obviously downregulated in BMSCs from aged humans and mice. Overexpressed miR-19a-3p evidently reduced aging-induced bone loss in mice and promoted osteogenic differentiation of BMSCs, while silenced miR-19a-3p manifestly increased aging-induced bone loss in mice and repressed osteogenic differentiation of BMSCs. Hoxa5 was significantly downregulated in the BMSCs from aged mice and contribute to miR-19a-3p-induced osteoblast differentiation as a direct target gene of miR-19a-3p. Furthermore, lncRNA Xist was found as a sponge of miR-19a-3p to repress BMSCs osteogenic differentiation. In conclusion, our study reveals the critical role of the lncRNA Xist/miR-19a-3p/Hoxa5 pathway in aging-induced osteogenic differentiation of BMSCs, indicating the potential therapeutic target for osteoporosis.

N6-methyladenosine (m6A) regulators are involved in the progression of various cancers via regulating m6A modification. However, the potential role and mechanism of the m6A modification in osteosarcoma remains obscure. In this study, WTAP was found to be highly expressed in osteosarcoma tissue and it was an independent prognostic factor for overall survival in osteosarcoma. Functionally, WTAP, as an oncogene, was involved in the proliferation and metastasis of osteosarcoma in vitro and vivo. Mechanistically, M6A dot blot, RNA-seq and MeRIP-seq, MeRIP-qRT-PCR and luciferase reporter assays showed that HMBOX1 was identified as the target gene of WTAP, which regulated HMBOX1 stability depending on m6A modification at the 3′UTR of HMBOX1 mRNA. In addition, HMBOX1 expression was downregulated in osteosarcoma and was an independent prognostic factor for overall survival in osteosarcoma patients. Silenced HMBOX1 evidently attenuated shWTAP-mediated suppression on osteosarcoma growth and metastasis in vivo and vitro. Finally, WTAP/HMBOX1 regulated osteosarcoma growth and metastasis via PI3K/AKT pathway. In conclusion, this study demonstrated the critical role of the WTAP-mediated m6A modification in the progression of osteosarcoma, which could provide novel insights into osteosarcoma treatment.

Background: N6-methyladenosine (m6A) regulators are involved in the progression of various cancers via regulating m6A modification. However, the potential role and mechanism of the m6A modification in osteosarcoma (OS) remains obscure. Methods: The expression of m6A regulators were detected using qPCR and western blot. Cell proliferation, colony formation, wound healing and transwell invasion assays were used to reveal the role of WTAP in the progression of OS. The mechanism of WTAP-mediated m6A modification was explored using M6A dot blot, RNA-seq and MeRIP-seq, MeRIP-qRT-PCR and luciferase reporter assays. Results: Here, WTAP was found to be high expression in OS tissue and it was an independent prognostic factor for OS patients . Functionally, WTAP, as an oncogene, was involved in the proliferation and metastasis of OS. Mechanistically, M6A dot blot, RNA-seq and MeRIP-seq, MeRIP-qRT-PCR and luciferase reporter assays showed that HMBOX1 is the target gene of WTAP, which regulated HMBOX1 stability in an m6A-dependent manner by targeting to the 3’UTR of HMBOX1 mRNA. In addition, HMBOX1 expression was downregulated in OS and negatively linked to WTAP expression in OS patients. Silenced HMBOX1 evidently attenuated shWTAP-mediated suppression on OS growth and metastasis in vivo and vitro. Finally, WTAP/HMBOX1 regulated OS growth and metastasis via PI3K/AKT pathway. Interpretation: The study demonstrates the critical role of the WTAP-mediated m6A modification in the progression of OS, which could provide novel insights into therapy of OS. Funding Statement: This study was supported by National Natural Science Foundation of China (Grant Nos. 81772866); National Natural Science Foundation of China (Grant Nos. 81502331); Natural Science Foundation of Hunan Province (Grant Nos. 2018JJ2617); Natural Science Foundation of Hunan Province (Grant Nos. 2016JJ3176); National Key Research and Development Program of China (No. 2016YFC1201800) ; Natural Science Foundation of Hunan Province (No. 2018SK2090). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: Informed consent was obtained from each patient or their guardians, and the study were approved by the Ethics Committee of The Third Xiangya Hospital of Central South University. All animal care and handling procedures were approved by the Institutional Animal Care and Use Committee of The Third Xiangya Hospital of Central South University, Changsha, China.