RESUMO
Chelerythrine (CHE) is widely found in many herbs and is the main alkaloid constituent of Toddalia asiatica (L.) LAM. It has been proved to exert remarkable antitumor, antifungal, anti-inflammatory, and antiparasitic effects. In osteosarcoma, CHE is reported to inhibit proliferation and promote apoptosis. However, the effect of CHE on cancer stem-like cells (CSCs), which contribute to metastasis and recurrence in osteosarcoma, is still largely unknown. In this study, we investigated the effects of CHE on the stemness and malignant behaviors of CSCs derived from osteosarcoma cells. CSCs were enriched by culturing in serum-free medium. The effects of CHE on stemness were measured by detecting stemness factors and sphere formation ability. The effects of CHE on chemosensitivity to doxorubicin and MTX were measured by Annexin V-FITC/PI double staining. The effects of CHE on CSC malignancy were measured by performing CCK-8, colony formation, tumor formation in soft agar, migration, and invasion assays. We first enriched CSCs from osteosarcoma cells, which were characterized by upregulated stemness markers, including Oct4, Nanog, and Nestin. The addition of CHE clearly decreased malignant behaviors, including colony formation, tumor formation in soft agar, migration, and invasion. CHE also inhibited stemness and thus induced the failure of sphere formation. Moreover, CHE promoted apoptosis induced by chemo agents, including doxorubicin (DOX) and methotrexate (MTX). After CHE treatment, the protein expression of MMP-2/9 was significantly decreased, potentially inhibiting invasion. CHE also exhibited an inhibitory effect on the phosphorylation of PI3K, AKT, and mTOR, which is an upstream regulatory signaling pathway of MMP-2/9. In summary, CSCs derived from U2OS and MG-63 cells, CHE could inhibit the stemness and malignant behaviors of CSCs potentially by inhibiting the PI3K/AKT/mTOR signaling pathway.
RESUMO
BACKGROUND: Hypoxia-induced oxidative stress is one of the main mechanisms of myocardial injury, which frequently results in cardiomyocyte death and precipitates life-threatening heart failure. Propofol (2,6-diisopropylphenol), which is used to sedate patients during surgery, was shown to strongly affect the regulation of physiological processes, including hypoxia-induced oxidative stress. However, the exact mechanism is still unclear. METHODS: Expression of LRPPRC, SLIRP, and Bcl-2 after propofol treatment was measured by RT-qPCR and western blot analyses. The effects of propofol under hypoxia were determine by assessing mitochondrial homeostasis and mitochondrial function, including the ATP level and mitochondrial mass. Autophagy/mitophagy was measured by detecting the presence of LC3B, and autophagosomes were observed by transmission microscopy. RESULTS: Propofol treatment inhibited cleaved caspase-9 and caspase-3, indicating its inhibitory roles in mitochondrial-related apoptosis. Propofol treatment also transcriptionally activated LRPPRC, a mitochondrial-associated protein that exerts multiple functions by maintaining mitochondrial homeostasis, in a manner dependent on the presence of hypoxia-induced factor (HIF)-1α transcriptional activity in H9C2 and primary rat cardiomyocytes. LRPPRC induced by propofol maintained the mitochondrial membrane potential (MMP) and promoted mitochondrial function, including ATP synthesis and transcriptional activity. Furthermore, LRPPRC induced by propofol contributes, at least partially, to the inhibition of apoptotic cell death induced by hypoxia. CONCLUSION: Taken together, our results indicate that LRPPRC may have a protective antioxidant effect by maintaining mitochondrial homoeostasis induced by propofol and provide new insight into the protective mechanism of propofol against oxidative stress.
