Zhu Guanghui, Xia Yu, Zhao Ziyue, Li Aoyu, Li Hui, Xiao Tao
Department of Orthopaedics, The Second Xiangya Hospital, Central South University, 139 Renmin Road, Changsha, 410011, Hunan, People's Republic of China.
Department of Pediatric Orthopedics, Hunan Children's Hospital, Changsha, Hunan, People's Republic of China.
Cancer Cell Int. 2022 Oct 29;22(1):330. doi: 10.1186/s12935-022-02746-0.
Long non-coding RNA X-inactive specific transcript (XIST) regulates the progression of a variety of tumors, including osteosarcoma. Bone marrow mesenchymal stem cells (BMSCs) can be recruited into osteosarcoma tissue and affect the progression by secreting exosomes. However, whether BMSCs derived exosomes transmit XIST to regulate the growth and metastasis of osteosarcoma and the related mechanism are still unclear.
In this study, BMSCs derived exosomes were used to treat human osteosarcoma cells MG63 and 143B, and the level of XIST in BMSCs was intervened by siRNA. CCK-8, EdU, transwell assays were used to analyze the changes of cell proliferation, migration and invasion. Bioinformatics analysis, RNA pulldown and dual-luciferase reporter gene assays validated the targeted relationship of XIST with miR-655 and the interaction between miR-655 and ACLY 3'-UTR. 143B/LUC cell line was used to establish an animal model of in situ osteosarcoma to verify the found effects of XIST on osteosarcoma. Oil Red O staining, Western blot and so on were used to detect the changes of lipid deposition and protein expression.
It was found that BMSCs derived exosomes promoted the proliferation, migration and invasion of osteosarcoma cells, and the down-regulation of XIST inhibited this effect. miR-655 mediated the role of BMSCs derived exosomal XIST in promoting the progression of osteosarcoma and down-regulation of miR-655 could reverse the effects of inhibiting XIST on the proliferation, migration and invasion of osteosarcoma cells. Meanwhile, animal level results confirmed that BMSCs derived exosomal XIST could promote osteosarcoma growth and lung metastasis by combining with miR-655. In-depth mechanism study showed that BMSCs derived exosomal XIST combined with miR-655 to increase the protein level of ACLY, which led to lipid deposition and activate β-catenin signal to promote the proliferation, migration and invasion of osteosarcoma cells.
This study showed that BMSCs derived exosomal XIST could enter osteosarcoma cells, bind and down-regulates the level of miR-655, resulting in an increase in the level of ACLY, thus increasing the lipid deposition and the activity of β-catenin signal to promote the growth and metastasis of osteosarcoma.
长链非编码RNA X染色体失活特异性转录本（XIST）调控包括骨肉瘤在内的多种肿瘤的进展。骨髓间充质干细胞（BMSCs）可被募集到骨肉瘤组织中，并通过分泌外泌体影响肿瘤进展。然而，BMSCs来源的外泌体是否传递XIST以调控骨肉瘤的生长和转移及其相关机制仍不清楚。
在本研究中，用BMSCs来源的外泌体处理人骨肉瘤细胞MG63和143B，并通过siRNA干预BMSCs中XIST的水平。采用CCK-8、EdU、transwell实验分析细胞增殖、迁移和侵袭的变化。通过生物信息学分析、RNA下拉实验和双荧光素酶报告基因实验验证XIST与miR-655的靶向关系以及miR-655与ACLY 3'-UTR的相互作用。利用143B/LUC细胞系建立原位骨肉瘤动物模型，以验证XIST对骨肉瘤的影响。采用油红O染色、蛋白质免疫印迹等方法检测脂质沉积和蛋白质表达的变化。
发现BMSCs来源的外泌体促进骨肉瘤细胞的增殖、迁移和侵袭，而XIST的下调抑制了这种作用。miR-655介导BMSCs来源的外泌体XIST在促进骨肉瘤进展中的作用，miR-655的下调可逆转抑制XIST对骨肉瘤细胞增殖、迁移和侵袭的影响。同时，动物水平的结果证实，BMSCs来源的外泌体XIST可通过与miR-655结合促进骨肉瘤生长和肺转移。深入的机制研究表明，BMSCs来源的外泌体XIST与miR-655结合增加了ACLY的蛋白水平，并导致脂质沉积和激活β-连环蛋白信号，从而促进骨肉瘤细胞的增殖、迁移和侵袭。
本研究表明，BMSCs来源的外泌体XIST可进入骨肉瘤细胞，结合并下调miR-655水平，导致ACLY水平升高，从而增加脂质沉积和β-连环蛋白信号活性，促进骨肉瘤的生长和转移。
