Background contextThere are many models of lumbar disc degeneration, but mechanical stress-induced lumbar disc degeneration is rare. Here we propose a mechanical stress-induced lumbar disc degeneration model to better understand the molecular mechanism of lumbar disc degeneration under stress stimulation.PurposeTo design a new model of lumbar disc degeneration under mechanical stressStudy designThe anatomic approach of the oblique lateral approach to lumbar fusion surgery was used to design a longitudinal compression device across the vertebral body of the rabbit to impose longitudinal load on the lumbar disc.MethodsNew Zealand white rabbits (n=30) were used. Screws were used to cross the rabbits’ lumbar vertebral bodies, and both sides of the screws were pressurized. Continuous compression was then performed for 28 days. Adjacent unpressurized lumbar discs serve as controls for pressurized lumbar discs. At 28 days after surgery, micro-computed tomography (CT) and magnetic resonance imaging (MRI) were performed on the rabbits’ lumbar discs. After the imaging examination, lumbar disc samples were removed, Safranin-O fast green and immunofluorescence was performed to detect the expression level of intervertebral disc degeneration-related proteins.ResultsThe CT results showed that the disc height did not decrease significantly after mechanical loading. The MRI results showed that the signals in the pressurized disc decreased 28 days after loading. The results of Safranin-O fast green showed that the cartilage component of the intervertebral disc after mechanical compression was significantly reduced. The immunofluorescence results showed that the expression of ADAMTS5 and MMP13 protein in the nucleus pulposus of the intervertebral disc after mechanical compression increased, while the expression of SOX9 decreased, and the difference was statistically significant. Aggrecan's protein expression decreased, but was not statistically significant.ConclusionsThis study designed a reliable model of disc degeneration in rabbits. It is more likely to mimic disc compression in the human body.Clinical significanceThis animal model can be used as a basic model to study the molecular physiological mechanisms of discogenic low back pain.

Abstract Background Osteosarcoma is a malignant tumor that tends to occur in adolescents. In recent years, surgical treatment has reduced mortality rates in patients with osteosarcoma. However, many patients still die of osteosarcoma, and further studies are needed to elucidate the complicated pathogenesis of this disease. Methods The function of circCHD7 was detected by transwell, clone formation, Cell Counting Kit 8, and apoptosis assays after knockdown of circCHD7 in 143B and HOS cells. Bioinformatics analysis was used to identify binding between miR-608 and circCHD7, and the results were further validated using luciferase, pull-down, and RNA immunoprecipitation assays. Bioinformatics and quantitative real-time polymerase chain reaction were used to identify downstream target genes of miR-608. The expression and effects of circCHD7 inhibitor were evaluated in stable sh-circCHD7 143B cell lines and a subcutaneous tumor model. Results CircCHD7, regulated by eIF4A3, was found to promote tumor proliferation and migration. Knockdown of circCHD7 and overexpression of miR-608 enhanced apoptosis and inhibited migration ability in osteosarcoma cells. The inhibitory effects of circCDH7 knockdown in 143B and HOS cells could be rescued by miR-608 inhibitor. Bioinformatics and western blotting results showed that miR-608 could regulate the expression of downstream matrix metalloproteinase 2 (MMP2) and Frizzled-4 (FZD4) and further modulate the Wnt/β-catenin pathway, thereby exerting inhibitory effects on osteosarcoma. Conclusion In this study, we discovered a new circRNA, circCHD7, that was regulated by eIF4A3 and modulated tumor growth through the miR-608/FZD4/MMP2 pathway. These findings provide insights into the potential application of circRNAs in the treatment of osteosarcoma.

Hypoxia is an indispensable factor for cancer progression and is closely associated with the Warburg effect. Circular RNAs (CircRNA) have garnered considerable attention in molecular malignancy therapy as they are potentially important modulators. However, the roles of circRNAs and hypoxia in osteosarcoma (OS) progression have not yet been elucidated. This study reveals the hypoxia-sensitive circRNA, Hsa_circ_0000566, that plays a crucial role in OS progression and energy metabolism under hypoxic stress. Hsa_circ_0000566 is regulated by hypoxia-inducible factor-1α (HIF-1α) and directly binds to it as well as to the Von Hippel-Lindau (VHL) E3 ubiquitin ligase protein. Consequentially, binding between VHL and HIF-1α is impeded. Furthermore, Hsa_circ_0000566 contributes to OS progression by binding to HIF-1α (while competing with VHL) and by confers protection against HIF-1α against VHL-mediated ubiquitin degradation. These findings demonstrate the existence of a positive feedback loop formed by HIF-1α and Hsa_circ_0000566 and the key role they play in OS glycolysis. Taken together, these data indicate the significance of Hsa_circ_0000566 in the Warburg effect and suggest that Hsa_circ_0000566 could be a potential therapeutic target to combat OS progression.

Intervertebral disc degeneration (IVDD) is the primary cause of low back pain; however, the molecular mechanisms involved in the pathogenesis of IVDD are not fully understood. Polo-like kinase 1 (PLK1) plays numerous roles in the cell cycle, including in cell proliferation and senescence. To investigate the involvement of PLK1 in IVDD, we used patient tissues and an animal model of IVDD. Samples were analyzed via immunoblotting, quantitative real-time polymerase chain reaction (qPCR), immunofluorescence, and immunohistochemistry. Our results demonstrated that PLK1 expression was decreased in nucleus pulposus cells (NPCs) of degenerative IVDs. The inhibition of PLK1 kinase activity in normal NPCs increased the expression of p53 protein, inhibited cell proliferation, and induced senescence. Our results suggest that PLK1 regulates the degeneration of the IVD through p53, revealing the function and mechanism of PLK1 in IVDD and providing a theoretical basis and experimental evidence for the potential treatment of low back pain.

Recently, various studies have identified circular RNAs (circRNAs) to play a significant role in tumorigenesis, thereby showing potential as novel tumor biomarkers. circSIPA1L1 is a newly discoveredcircular RNA, which is formed by back-splicing of SIPA1L1 and is found increased in osteosarcoma (OS). Nevertheless, the specific functions of circSIPA1L1 in OS remain unknown. In the present study, circSIPA1L1 was obtained from a previously reported circRNA microarray in the GEO database (GSE96964). Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to assess the mRNA level of circSIPA1L1 in OS cell lines and tissue samples. Bioinformatics analysis, luciferase reporter assays, real-time PCR, RNA pull-down assays and RNA immunoprecipitation (RIP) were employed to verify the binding of circSIPA1L1 with miR-411-5p. Xenograft tumor models were established to identify the role of circSIPA1L1 in vivo . A series of in vitro experiments, such as western blotting, colony formation, transwell assays and anoikis assay were employed to confirm the relationship across circSIPA1L1, miR-411-5p, and RAB9A. Our study confirmed circSIPA1L1 to be upregulated in both human OS samples and OS cell lines. Mechanistically, circSIPA1L1 could serve as a miR-411-5p molecular sponge to increase RAB9A expression, which was confirmed to be a tumor promoter mediating carcinogenesis. Silencing of circSIPA1L1 attenuated the vitality, invasion, migration and proliferation of OS cell lines both in vivo and in vitro . miR-411-5p inhibition or RAB9A overexpression reversed the anti-tumor effects caused by circSIPA1L1 knockdown. Briefly, circSIPA1L1 could function as a driver gene in OS and initiate OS tumorigenesis through the miR-411-5p/RAB9A signaling pathway, which might become a potential therapeutic biomarker for OS treatment.

Background: Emerging evidence has reported that circular RNAs (circRNAs) are aberrantly expressed and act as significant regulators in pathological processes of chronic obstructive pulmonary disease (COPD). Here, the purpose of this article was to evaluate and clarify the biological functions and mechanism of circRNA single stranded interacting protein 1 (circ-RBMS1) in cigarette smoke (CS)-induced COPD. Methods: Human bronchial epithelial cells 16HBE treated with or without cigarette smoke extract (CSE) were used in the experimental group in vitro. Levels of circ-RBMS1, microRNA (miR)-197-3p, and F-box only protein 11 (FBXO11) were detected using quantitative real-time polymerase chain reaction and Western blot. The present study used cell counting kit-8 (CCK-8), 5-ethynyl-2MODIFIER LETTER PRIME-deoxyuridine (EDU), flow cytometry and Western blot assays to determine the survival of 16HBE cells. The activity of interleukin (IL)-1 beta, tumor necrosis factor (TNF-alpha), malondialdehyde (MDA) and superoxide dismutase (SOD) was evaluated using the relative commercial kits. Dual-luciferase activity and RIP assays were used to identify the target relationship between miR-197-3p and circ-RBMS1 or FBXO11. Results: Circ-RBMS1 was highly expressed in COPD patients, and CSE induced an increased expression of circ-RBMS1 in a dose-dependent manner. Functionally, knockdown of circ-RBMS1 attenuated CSE-induced apoptosis, inflammation and oxidative stress in 16HBE cells. Circ-RBMS1 directly targeted miR-197-3p, and miR-197-3p inhibition reversed the effects of circ-RBMS1 knockdown on CSE-induced 16HBE cells. FBXO11 was a target of miR-197-3p. MiR-197-3p overexpression or FBXO11 silencing reduced the apoptosis, inflammation and oxidative stress in CSE-induced 16HBE cells. Moreover, miR197-3p exerted its effects by targeting FBXO11. Additionally, circ-RBMS1 acted as a sponge for miR-197-3p to positively regulate FBXO11 expression in 16HBE cells. Conclusion: Circ-RBMS1 knockdown alleviated CSE-induced apoptosis, inflammation and oxidative stress in 16HBE cells via miR-197-3p/FBXO11 axis, suggesting a new insight into the of CS-induced COPD.

BackgroundRecently, various studies have identified circular RNAs (circRNAs) to play a significant role in tumorigenesis, thereby showing potential as novel tumor biomarkers. circSIPA1L1 is a new-found circular RNA formed by back-splicing of SIPA1L1 and is found increased in osteosarcoma (OS). Nevertheless, the specific functions of circSIPA1L1 in OS remain unknown. MethodsIn the present study, circSIPA1L1 was obtained from a previously reported circRNA microarray (GSE96964) in the GEO database. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to assess the mRNA level of circSIPA1L1 in OS cell lines and tissue samples. Bioinformatics analysis, luciferase reporter assays, real-time PCR, RNA pull-down assays and RNA immunoprecipitation (RIP) were employed to verify the binding of circSIPA1L1 with miR-411-5p. Xenograft tumor models were established to identify the role of circSIPA1L1 in vivo . A series of in-vitro experiments, such as western blotting , colony formation, transwell assays and anoikis assay were employed to confirm the relationship across circSIPA1L1, miR-411-5p, and RAB9A. ResultsOur study confirmed circSIPA1L1 to be upregulated in both human OS samples and OS cell lines. Mechanistically, circSIPA1L1 could serve as a miR-411-5p molecular sponge to increase RAB9A expression, which was confirmed to be a tumor promoter mediating carcinogenesis. Silencing of circSIPA1L1 attenuated the vitality, invasion, migration and proliferation of OS cell lines both in vivo and in vitro . miR-411-5p inhibition or RAB9A overexpression reversed the anti-tumor effects caused by circSIPA1L1 knockdown. ConclusionBriefly, circSIPA1L1 acts as a driver gene in OS and could initiate OS tumorigenesis via the miR-411-5p/RAB9A axis, which might become a potential therapeutic biomarker for OS treatment.