Aims Increasing evidences have suggested that microRNAs (miRNAs) play crucial roles in cancer development and progression. Our previous study showed that the level of miR-217 was remarkably lower in GCT cells and tissues, and the re-expression of miR-217 induced an inhibitory effect on occurrence and development of GCT in vitro. However, the mechanisms underlying the proliferation inhibition effect of miR-217 in GCT cells still remain unknown. Thus, this article is aimed to explore the mechanisms underlying the proliferation inhibition effect of miR-217 in GCT cells. Methods The GCT cells proliferative potential was measured by use of the MTT assay and BrdU straining. The changes in migration and invasion of GCT cells was determined by transwell assay. Finally, western blot and RT-PCR assays were employed to evaluate the expression of OPG/RANKL/RANK signaling pathway related-proteins. Result In the present study, the excessive upregulation of miR-217 markedly suppressed GCT cell proliferation and tumorigenesis in vitro and in vivo. Meanwhile, the overexpression of miR-217 could inhibit OPG/RANKL/RANK signal pathway in vitro and in vivo. Furthermore, the ALP activity was also significantly decreased in GCT cells by miR-217 treatment. Importantly, miR-217 could inhibit autophagy-related protein expression and autophagosomes/autolysosomes formation in GCT cells and tissues. Conclusion These results suggest that the upregulation of miR-217 inhibit the occurrence and development of GCT through inhibiting autophagy. This study also offers an effective therapeutic target to improve the survival rates of patients with CGT in the future.

Background Increasing evidence suggests that microRNAs (miRNAs) play a crucial role in cancer development and progression. Our previous study showed remarkably lower levels of miR-217 in GCT cells and tissues, and miR-217 re-expression inhibited the occurrence and development of GCT in vitro; however, the associated mechanisms remain unknown. Thus, this study aimed to explore the mechanisms underlying the proliferation inhibitory effect of miR-217 in GCT cells. Methods The proliferative potential of the GCT cells was measured with an MTT assay and BrdU straining. Changes in GCT cell migration and invasion was assessed by a transwell assay. Finally, Western blot and RT-PCR assays were employed to evaluate OPG/RANKL/RANK signaling pathway-related protein expression. Results The excessive upregulation of miR-217 markedly suppressed GCT cell proliferation and tumorigenesis both in vitro and in vivo. miR-217 overexpression could inhibit the OPG/RANKL/RANK signaling pathway in vitro and in vivo. Furthermore, ALP activity was significantly decreased in GCT cells following miR-217 treatment. Importantly, miR-217 could inhibit autophagy-related protein expression and autophagosome/autolysosome formation in GCT cells and tissues. Conclusion These results suggest that miR-217 upregulation could inhibit the occurrence and development of GCT by blocking autophagy. These findings offer an effective therapeutic target to improve the survival rates of patients with CGT in the future.

BackgroundOsteosarcoma (OS) is a highly malignant tumor. Improving chemotherapeutic resistance is very important to improve the survival rate of OS. Exosomes and microRNAs (MiRNA) play important roles in the mechanism of chemotherapeutic resistance transmission. More and more researches focus the mechanism of miRNAs carried by exosomes in the transmission of chemotherapeutic resistance of OS. This study focused on exploring the mechanism of exosomal miR-331 in the transmission of chemoresistance in OS.MethodsWe cultured OS drug-resistant cells and extracted exosomes of these cells. The secretion and uptake of exosomes in OS drug-resistant cells and OS cells (OSCs) were confirmed by fluorescence tracking assay and transwell experiments. The differential expression of microRNA-331 (miR-331) in exosomes of OS resistant and OS cells was investigated by RT-PCR. The effects of drug-resistant exosomes on proliferation and migration of OS cells were determined by MTT assay and scratches assay. MDC staining, RT-PCR, and Western blot were used to detect the role of autophagy which regulated by drug-resistant cell-derived exosom-miR-331.ResultsWe found that the expression difference of miR-331 between MG63/CDDP and MG63 was the most significant. Drug resistant OSCs secreted exosomes and were ingested by OSCs, which then promoted OSCs to acquire drug resistance. In addition, exosomes secreted by drug-resistant OSCs promote drug resistance by carrying miRNAs. Interestingly, inhibition of miRNA resulted in reduced drug resistance transmission of exosomes. Finally, we found that the exosomes secreted by drug-resistant OSCs could induce autophagy of OSCs by carrying miR-331, thus making OSCs acquire drug resistance. Inhibition of miR-331 can effectively improve drug resistance of OSCs.ConclusionsChemoresistant OSCs-derived exosomes promote the transmission of drug resistance by carrying miR-331 and inducing autophagy. Inhibition of miR-331 could effectively alleviate drug resistance of OSCs.