Background: In a previous study, we found that melatonin inhibits MG-63 osteosarcoma cell proliferation; however, the underlying mechanisms remain elusive. Mitogen-activated protein kinase (MAPK) and Akt signaling pathways play key roles in the anticancer effects of melatonin. Aims: The present study investigated whether MAPK and Akt signaling pathways are involved in melatonin's antiproliferative actions on the human MG-63 osteosarcoma cells. Methods/Results: Western blot analysis confirmed that melatonin significantly inhibited phosphorylation of ERK1/2 but not p38, JNK, or Akt. The expression of ERK1/2, p38, JNK, and Akt was not altered by melatonin. PD98059 and melatonin alone, and especially in combination, significantly inhibited cell proliferation. The changes included G₁ and G₂/M phase arrest of the cell cycle, and a downregulation of the expression at both the protein and mRNA levels of cyclin D1 and CDK4 (related to the G₁ phase) and of cyclin B1 and CDK1 (related to the G₂/M phase) as measured by flow cytometry after propidium iodide staining, and both western blot and real-time PCR, respectively. Furthermore, the combination of PD98059 and melatonin synergistically and markedly augmented the action of either agent alone. Co-immunoprecipitation further confirmed that there was an interaction between p-ERK1/2 and cyclin D1, CDK4, cyclin B1, or CDK1, which was blunted in the presence of melatonin or PD98059. Conclusion: These findings suggest that melatonin's antiproliferative action is mediated by inhibition of the ERK1/2 signaling pathway rather than the p38, JNK, or Akt pathways.

Osteoarthritis (OA) is a degenerative disease of articular cartilage. The pathogenesis of OA remains to be fully elucidated, and several studies have found that oxidative stress is important in its pathogenesis. Baicalin is well known and has already been investigated for its role of inhibiting the oxidative stress pathway. Thus, the present study aimed to investigate the role of baicalin on the inhibition of oxidative stress in endplate chondrocytes induced by hydrogen peroxide (H2O2). Following treatment of endplate chondrocytes with different doses of H2O2 with or without baicalin for different incubation durations, a CCK‑8 assay and Annexin V/PI staining were used to measure the cell proliferation and apoptotic rates to identify the optimal experimental conditions. Subsequently, for examining the effects and underlying mechanism of baicalin on oxidative stress, the protein expression levels of cleaved‑poly (ADP‑ribose) polymerase (PARP), B‑cell lymphoma‑2‑associated X protein (Bax) and pro‑caspase‑3 were analyzed using western blot analysis, intracellular anti‑oxidant activities, including those of malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide (NO), were quantified, and the levels of endothelial nitric oxide synthase (eNOS) were examined using reverse transcription‑polymerase chain reaction analysis. The results revealed that the oxidative stress of endplate chondrocytes induced by 0.5 mM H2O2 for 4 h were the most appropriate conditions for experiments, and pretreatment with 100 µmol/l baicalin for 1 h effectively reversed the effect of H2O2 on the endplate chondrocytes. In addition, Annexin V/PI staining demonstrated that the cell death induced by H2O2 was apoptotic, and baicalin reversed the apoptosis induced by oxidative stress. H2O2 activated PARP cleavage, and the expression of Bax and pro‑caspase‑3; however, baicalin inhibited the expression of these apoptotic signaling indicators. Baicalin also reduced the levels of MDA, and increased the levels of SOD and NO. Baicalin also significantly elevated the mRNA levels of eNOS in endplate chondrocytes. Therefore, the results of the present study showed that baicalin significantly inhibited the oxidative stress in endplate chondrocytes induced by H2O2, and decreased cell apoptosis.

Anti-apoptotic and anti-inflammatory treatments are imperative for skeletal muscle regeneration following injury. Baicalin is well known and has previously been investigated for its role in the treatment of injury and inflammatory diseases. Therefore, the present study aimed to investigate the effects of baicalin in inhibiting apoptosis of C2C12 myoblasts and preventing skeletal muscle injury. A cell counting kit-8 (CCK-8) assay and Annexin V/PI staining were initially performed to measure cell viability and apoptosis under conditions of H 2 o 2 exposure with or without baicalin. Subsequently, oxidative activity, mitochondrial function, mitochondrial apoptogenic factors and caspase proteins were analyzed to examine the mechanism underlying the effect of baicalin on inhibiting apoptosis in C2C12 myoblasts. Furthermore, BALB/C mice with skeletal muscle injuries were established, and the potential application of baicalin for anti-apoptotic and anti-inflammatory effects was examined via small animal β-2-[18F]-fluoro-2-deoxy-D-glucose ( 18 F-FDG) positron emission tomography (PET) imaging and pathological examination. The CCK-8 assay and Annexin V/PI staining revealed cell death in the C2C12 myoblasts induced by H 2 o 2 , which was apoptotic, and this was effectively reversed by treatment with baicalin. H 2 o 2 increased the reactive oxygen species and malondialdehyde levels in C2C12 myoblasts, which was caused by mitochondrial dysfunction, decreased expression of cytochrome c and apoptosis-inducing factor from cytosolic and mitochondrial fractions, and activated expression of caspase-3 and caspase-9; however, treatment with baicalin reversed these effects. In addition, small animal PET imaging revealed that treatment with baicalin decreased the accumulation of FDG by ~65.9% in the injured skeletal muscle induced by H 2 o 2 . These pathological results also confirmed the protective effect of baicalin on injured skeletal muscle. Taken together, the results of the present study indicated that baicalin effectively inhibited the apoptosis of C2C12 myoblasts and protected skeletal muscle from injury, which may have potential therapeutic benefits for patients in a clinical setting.

Aim: The diagnosis of vulnerable atherosclerotic plaques remains challenging. This study labeled ultrasmall superparamagnetic iron oxide with rhodamine (USPIO-R) and evaluated USPIO-R for imaging atherosclerotic plaques. Methods: Apolipoprotein E-deficient mice were fed a high-fat diet and underwent MRI before and after an intravenous injection of USPIO-R. Subsequently, an aortic specimen from the mice was removed and sliced for fluorescence imaging and Prussian blue and immunofluorescent staining. Results: T2 signal loss appeared and persisted in the aortic plaque postinjection, and spontaneous fluorescence from the plaque was observed. The accumulated mechanism of USPIO-R by plaque was the macrophage internalization by Prussian blue and immunofluorescence. Conclusion: USPIO-R is a promising dual-modality probe for diagnosing and monitoring vulnerable atherosclerotic plaques.

Background Many studies reported that lifestyle, psychosocial characteristics, and sleep status related to sarcopenia, while few studies provided evidence of causal relationships between them. Methods The data used in our study were from UK Biobank, FinnGen Release 8, and large genome-wide association study meta-analyses. Two-sample MR was conducted to identify the causal associations of 21 traits of lifestyle, psychosocial characteristics, and sleep status with six traits of sarcopenia. Benjamini–Hochberg correction was performed to reduce the bias caused by multiple tests. Risk factor analyses were performed to explore the potential mechanism behind the exposures. Results MR analyses after adjustment proved the causal roles of coffee intake, education years, smoking, leisure screen time, and moderate-to-vigorous intensity physical activity during leisure time (MVPA) in sarcopenia was proven while providing no significant evidence for causal roles for carbohydrates intake, protein intake, alcohol, and sleep status in sarcopenia. Conclusions Our results strongly support that coffee intake, education years, smoking, leisure screen time, and MVPA played significantly causal roles in sarcopenia, which may provide new intervention strategies for preventing the development of sarcopenia.