In our previous study,
osteosarcoma advanced locally, and
metastasis was promoted through the secretion of large number of small extracellular vesicles, followed by suppressing osteoclastogenesis via the upregulation of
microRNA (miR)-146a-5p. An additional 12
miRNAs in small extracellular vesicles were also detected ≥6× as frequently in high-grade
malignancy with the capacity to metastasize as in those with a low metastatic potential. However, the utility of these 13
miRNAs for determining the prognosis or diagnosis of
osteosarcoma has not been validated in the clinical setting. In the present study, the utility of these
miRNAs as prognostic and diagnostic markers was therefore assessed. In total, 30 patients with
osteosarcoma were retrospectively reviewed, and the survival rate was compared according to the serum
miRNA levels in 27 patients treated with
chemotherapy and surgery. In addition, to confirm diagnostic competency for
osteosarcoma, the serum
miRNA levels were compared with those in patients with other bone
tumors (n=112) and healthy controls (n=275). The patients with
osteosarcoma with high serum levels of several
miRNAs (miR-146a-5p, miR-1260a, miR-487b-3p, miR-1260b and miR-4758-3p) exhibited an improved survival rate compared with those with low levels. In particular, patients with high serum levels of miR-1260a exhibited a significantly improved overall survival rate,
metastasis-free survival rate and disease-free survival rate compared with those with low levels. Thus, serum miR-1260a may potentially be a prognostic marker for patients with
osteosarcoma. Moreover, patients with
osteosarcoma had higher serum miR-1261 levels than those with benign or intermediate-grade bone
tumors and thus may be a potential therapeutic target, in addition to being useful for differentiating whether or not a bone
tumor is high-grade. A larger investigation is required to clarify the actual utility of these
miRNAs in the clinical setting.