MicroRNA‑336 directly targets Sox‑2 in osteosarcoma to inhibit tumorigenesis

EWS promotes cell proliferation and inhibits cell apoptosis by regulating miR-199a-5p/Sox2 axis in osteosarcoma

OBJECTIVE

Osteosarcoma is one of the most common malignant bone tumors which mainly occurs in children and adolescents. It is characterized by high malignancy and high metastasis rate, resulting in high mortality and disability. Accumulating studies have validated that long noncoding RNAs (lncRNAs) exerted vital roles in multiple cancer progression by regulating the expression of specific genes. This work aimed to explore the potential molecular mechanism of EWS in osteosarcoma.

RESULTS

In this study, we discovered that both EWS and Sox2 were highly expressed in osteosarcoma tissue samples. In addition, the expression of EWS was positively associated with Sox2 level. We conducted a series of functional assays and observed that Sox2 overexpression could significantly overturned the enhancement of cell proliferation and the decline of cell apoptosis induced by EWS knockdown in osteosarcoma. Moreover, we found a key upstream regulatory gene of Sox2: miR-199a-5p.

CONCLUSIONS

Through molecular biology studies and rescue assays, we further demonstrated that EWS promotes tumor growth through the miR-199a-5p/Sox2 signaling axis in osteosarcoma. These findings may provide an important theoretical basis for the clinical diagnosis and treatment of osteosarcoma.

miRNA signatures in childhood sarcomas and their clinical implications

Progresses in multimodal treatments have significantly improved the outcomes for childhood cancer. Nonetheless, for about one-third of patients with Ewing sarcoma, rhabdomyosarcoma, or osteosarcoma steady remission has remained intangible. Thus, new biomarkers to improve early diagnosis and the development of precision-targeted medicine remain imperative. Over the last decade, remarkable progress has been made in the basic understanding of miRNAs function and in interpreting the contribution of their dysregulation to cancer development and progression. On this basis, this review focuses on what has been learned about the pivotal roles of miRNAs in the regulation of key genes implicated in childhood sarcomas.

SPOCD1 promotes cell proliferation and inhibits cell apoptosis in human osteosarcoma

Osteosarcoma is the most common type of malignant bone tumors that typically affects adolescents and children. The spen paralogue and orthologue C‑terminal domain containing 1 (SPOCD1) is a newly identified molecule that has been indicated to discriminate progressive from non‑progressive bladder cancers. However, the role of SPOCD1 in human solid tumors remains largely unknown. In the present study, SPOCD1 was upregulated in clinical osteosarcoma tissues compared with adjacent non‑cancerous tissues. Furthermore, SPOCD1 was upregulated in osteosarcoma cell lines and expression was particularly increased in highly invasive cells MG63 and SAOS2. Further investigation revealed that downregulation of SPOCD1 inhibited the MG63 and SAOS2 osteosarcoma cell colony formation and proliferation capacity. In addition, cell apoptosis was promoted by knockdown of SPOCD1 in MG63 and SAOS2 cells. These effects were confirmed by measuring the Ki67 and PCNA expression. In addition, SPOCD1 positively regulated the expression of vascular endothelial growth factor A (VEGF‑A). Knockdown of VEGF‑A blunted SPOCD1 downregulation‑mediated inhibition of cell proliferation and induction of cell apoptosis. These results suggested that SPOCD1 may act as a pro‑oncogenic factor in osteosarcoma. Inhibition of VEGF may aid in treating osteosarcoma in clinic.