Luteolin rescues postmenopausal osteoporosis elicited by OVX through alleviating osteoblast pyroptosis via activating PI3K-AKT signaling.

BACKGROUND: Recently, osteoblast pyroptosis has been proposed as a potential pathogenic mechanism underlying osteoporosis, although this remains to be confirmed. Luteolin (Lut), a flavonoid phytochemical, plays a critical role in the anti-osteoporosis effects of many traditional Chinese medicine prescriptions. However, its protective impact on osteoblasts in postmenopausal osteoporosis (PMOP) has not been elucidated. PURPOSE: This research aimed to determine the effect of Lut in ameliorating PMOP by alleviating osteoblast pyroptosis and sustaining osteogenesis. STUDY DESIGN: This research was designed to investigate the novel mechanism of Lut in alleviating PMOP both in cell and animal models. METHODS: Ovariectomy-induced PMOP models were established in mice with/without daily gavaged of 10 or 20 mg/kg body weight Lut. The impact of Lut on bone microstructure, metabolism and oxidative stress was evaluated with 0.104 mg/kg body weight Estradiol Valerate Tablets daily gavaged as positive control. Network pharmacological analysis and molecular docking were employed to investigate the mechanisms of Lut in PMOP treatment. Subsequently, the impacts of Lut on the PI3K/AKT axis, oxidative stress, mitochondria, and osteoblast pyroptosis were assessed. In vitro, cultured MC3T3-E1(14) cells were exposed to H2O2 with/without Lut to examine its effects on the PI3K/AKT signaling pathway, osteogenic differentiation, mitochondrial function, and osteoblast pyroptosis. RESULTS: Our findings demonstrated that 20 mg/kg Lut, similar to the positive control drug, effectively reduced systemic bone loss and oxidative stress, and enhanced bone metabolism induced by ovariectomy. Network pharmacological analysis and molecular docking indicated that the PI3K/AKT axis was a potential target, with oxidative stress response and nuclear membrane function being key mechanisms. Consequently, the effects of Lut on the PI3K/AKT axis and pyroptosis were investigated. In vivo data revealed that the PI3K/AKT axis was deactivated following ovariectomy, and Lut restored the phosphorylation of key proteins, thereby reactivating the axis. Additionally, Lut alleviated osteoblast pyroptosis and mitochondrial abnormalities induced by ovariectomy. In vitro, Lut intervention mitigated the inhibition of the PI3K/AKT axis and osteogenesis, as well as H2O2-induced pyroptosis. Furthermore, Lut attenuated ROS accumulation and mitochondrial dysfunction. The effects of Lut, including osteogenesis restoration, anti-pyroptosis, and mitochondrial maintenance, were all reversed with LY294002 (a PI3K/AKT pathway inhibitor). CONCLUSION: In summary, Lut could improve mitochondrial dysfunction, alleviate GSDME-mediated pyroptosis and maintain osteogenesis via activating the PI3K/AKT axis, offering a new therapeutic strategy for PMOP.

[Clinical observation of different surgical methods for metaphyseal sequelae of ulna].

OBJECTIVE: To investigate the effect and safety of ulnar osteochondroma resection, ulnar minimally invasive osteotomy, external fixation and ulnar lengthening in the treatment of forearm deformity of metaphyseal extension of ulna. METHODS: From August 2005 to December 2013, there were 20 cases of ulnar metaphyseal sequelae, including 15 males and 5 females, aged from 7 to 13(10.00±2.34) years, the course of disease ranged for 6 to 11(8.10±1.52) months. The clinical manifestations were shortening of the affected forearm and bending to the ulnar side. The postoperative evaluation included pain, activities of daily living, orthopedic effect and the range of motion of wrist, elbow and forearm. The radiological evaluation included ulnar length, radial joint inclination angle and wrist epiphysis growth. RESULTS: All patients healed without infection. The only operation related to complications was ulnar lengthening, including 1 case of nonunion, 2 cases of ulnar lengthening callus fracture and 1 case of temporary radial nerve palsy. All patients were followed up for 4 to 7.5 years, with an average of (6.03±1.33) years. There were statistically significant differences in changes of wrist radial deviation, ulnar deviation, forearm pronation and supination in all cases (P<0.05). Radiological evaluation parameters (ulnar variance, radial joint angle, wrist slip) were improved, and the differences were statistically significant(P<0.05). The modified Green and O'Brien wrist function scores at the last follow-up were significantly different from those before operation (P<0.05). The clinical effect of wrist joint was significantly different from that before operation (P<0.05). The Mayo elbow function scoreat the latest follow-up was significantly different from that before operation (P<0.05). The clinical effect of elbow joint was significantly different from that before operation (P<0.05). CONCLUSION: Ulnar lengthening is not beneficial to prevent the development of long-term deformity. Simple resection of osteochondroma of distal ulna is beneficial to prevent the development of deformity. Patients with limited rotation of wrist joint and forearm and strong demand for improvement of appearance can be actively treated.

Cryptotanshinone interferes with chondrocyte apoptosis in osteoarthritis by inhibiting the expression of miR­574­5p.

Chondrocyte apoptosis is an important factor in the development and progression of osteoarthritis (OA). Cryptotanshinone (CTS) can inhibit chondrocyte apoptosis, but the specific mechanism remains unknown. The aim of the present study was to explore how CTS may affect chondrocyte apoptosis. Reverse transcription­quantitative PCR and western blotting were used to validate microRNA (miR)­574­5p, YY1­associated factor 2 (YAF2), Bcl­2 and Bax expression levels. H&E, Safranin O and TUNEL staining assays were used to evaluate the apoptosis of arthritic chondrocytes in vivo. A Cell Counting Kit­8 assay and flow cytometry were performed to detect cell proliferation and apoptosis of chondrocytes in vitro. The methylation level of the miR­574­5p promoter was measured via methylation specific PCR. The degree of chondrocyte apoptosis and the expression levels of YAF2 and Bcl­2 were decreased in the mice with OA, and were increased in the OA + CTS mice, while the expression levels of miR­574­5p and Bax showed opposite changes. Furthermore, the degree of chondrocyte apoptosis and the expression levels of the aforementioned key factors in chondrocytes were consistent with those observed in vivo. The methylation degree of the miR­574­5p promoter was increased by the addition of CTS, and was reduced after the addition of a methylation inhibitor, 5­aza­CdR, indicating that CTS could regulate the methylation of miR­574­5p promoter. The present study suggested that CTS could downregulate the expression of miR­574­5p by regulating its methylation, and thus, could improve YAF2 expression and affect chondrocyte apoptosis.

Long noncoding RNA BSN-AS2 induced by E2F1 promotes spinal osteosarcoma progression by targeting miR-654-3p/SYTL2 axis.

Spinal osteosarcoma (OS) is a rare and aggressive malignancy. Long noncoding RNA (lncRNA) BSN-AS2 has been shown to be an oncogenic gene in several cancers. However, the role and function of BSN-AS2 in spinal OS were unfamiliar. Our study identified that BSN-AS2 expression was boosted in spinal OS tissues and cell lines. Transcription factor E2F1 induced the upregulation of BSN-AS2 expression in spinal OS cells. Afterwards, loss-of-function assays indicated that BSN-AS2 depletion reduced cell proliferation, migration and invasion as well as promoted cell apoptosis in spinal OS. Thereafter, RIP, RNA pull down and luciferase reporter assays manifested BSN-AS2 could sponge miR-654-3p in spinal OS. After that, the binding effect of between miR-654-3p and SYTL2 was proved. Finally, rescue experiments illustrated that miR-654-3p inhibition or SYTL2 overexpression could counteract the inhibitory effect caused by BSN-AS2 deficiency on spinal OS progression. In conclusion, the availability of miR-654-3p was antagonized by E2F1-induced BSN-AS2 for SYTL2-meidated spinal OS progression.

ELK1-induced upregulation of long non-coding RNA MIR100HG predicts poor prognosis and promotes the progression of osteosarcoma by epigenetically silencing LATS1 and LATS2.

Osteosarcoma (OS) is the commonest malignant bone tumor in the world. High incidence of OS has gradually become a social problem. Recent years, numerous studies have revealed that long non-coding RNAs (lncRNAs) are crucial regulators in the tumor progression. As a member of lncRNA family, MIR100HG has been reported to be an oncogene in breast cancer and acute megakaryoblastic leukemia. Nevertheless, the specific role of MIR100HG in osteosarcoma is still unclear. In this study, we investigated the biological function and molecular mechanism of MIR100HG in the progression of osteosarcoma. At first, we measured the high expression of MIR100HG in OS tissues and cell lines by qRT-PCR. Kaplan-Meier method revealed that high expression of MIR100HG is a factor for the poor prognosis of OS patients (P = 0.004). To explore the effect of MIR100HG on the biological processes of OS, loss-of-function assays were conducted in OS cells. Functionally, MIR100HG knockdown suppressed cell proliferation, cell cycle progression while promoted cell apoptosis. Mechanistically, MIR100HG was upregulated by the transcription factor ELK1. The upregulation of MIR100HG led to the inactivation of Hippo pathway. Furthermore, we found that MIR100HG inactivated Hippo pathway in OS cells by epigenetically silencing LATS1 and LATS2. Rescue assays demonstrated that LATS1/2 involved in MIR100HG-mediated OS progression. In summary, our study indicated that ELK1-induced upregulation of MIR100HG promoted OS progression by epigenetically silencing LATS1 and LATS2 and inactivating Hippo pathway.