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.

Programmed osteocyte death might be a pathogenesis of steroid-related avascular necrosis of the femoral head (SANFH). Autophagy-related gene 5 (ATG5) can activate the unfolded protein response pathway under endoplasmic reticulum stress (ERS) to participate in cell regulation, but the regulatory mechanism remains unclear. We examined the role of ERS in SANFH pathogenesis by studying the ATG5 participation mechanism in osteoblast apoptosis regulation to provide a theoretical basis for developing new SANFH therapeutic targets. Rat bone marrow mesenchymal stem cells cultured in vitro underwent osteogenic induction and alizarin red staining. The resultant osteoblasts were divided into Control, SANFH (methylprednisolone-treated), SANFH+ATG5 small interfering RNA (siRNA) (methylprednisolone-treated ATG5 siRNA transfection) groups. Beclin 1, MAP1LC3, ATG5, PERK, and caspase-3, -9, and -12 mRNA and protein expression levels were detected, the osteoblast survival rate was measured, and apoptosis was detected. The relationship between Beclin 1, MAP1LC3, ATG5, PERK, and caspase-3, -9, and -12 mRNA and protein expression levels and osteoblast apoptosis was analyzed. The SANFH group had enhanced expression of the autophagy-related genes Beclin 1 and MAP1LC3 and numerous autophagosomes were formed. Osteoblast injury stimulated ERS. ATG5 siRNA inhibited the glucocorticoid-induced osteoblast autophagy and ERS. The ER stimulated the caspase-12/9/3 cascade through ATG5 to enhance apoptosis and improve persistent ERS. The continuous action of methylprednisolone increased Beclin 1 and MAP1LC3 gene expression, resulting in bone cell injury and stimulating ERS. The ER activated the caspase-12/9/3 cascade via ATG5 under persistent and unchangeable ERS, leading to apoptosis and SANFH.

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.