Melatonin Alleviates Pyroptosis of Retinal Neurons Following Acute Intraocular Hypertension.

BACKGROUND: Glaucoma is a multifactorial optic neuropathy progressively characterized by structural loss of Retinal Ganglion Cells (RGCs) and irreversible loss of vision. High Intraocular Pressure (HIOP) is a high-risk factor for glaucoma. It has been reported that the mechanisms of the loss of RGCs are explored in-depth after acute HIOP injury, such as apoptosis, autophagy, and necrosis. However, pyroptosis, a novel type of pro-inflammatory cell programmed necrosis, is rarely reported after HIOP injury. Research studies also showed that melatonin (MT) possesses substantial anti-inflammatory properties. However, whether melatonin could alleviate retinal neuronal death, especially pyroptosis, by HIOP injury is still unclear. OBJECTIVE: This study explored pyroptosis of retinal neurons and the effects of melatonin in preventing retinal neurons from pyroptosis after acute HIOP injury. METHODS: An acute HIOP model of rats was established by increasing the IOP followed by reperfusion. Western Blot (WB) was adopted to detect molecules related to pyroptosis at the protein level, such as GSDMD, GASMDp32, Caspase-1, and caspase-1 p20, and the products of inflammatory reactions, such as IL -18 and IL-1ß. At the same time, immunofluorescence (IF) was used to co-localize caspase-1 with retinal neurons to determine the position of caspase-1 expression. Morphologically, ethidium homodimer III staining, a method commonly used to evaluate cell death, was carried out to stain dead cells. Subsequently, Lactate Dehydrogenase (LDH) cytotoxicity assay kit was used to quantitatively analyze the LDH released after cell disruption. RESULTS: The results suggested that pyroptosis played a vital role in retinal neuronal death, especially in the Ganglion Cell Layer, by acute HIOP injury and peaked at 6h after HIOP injury. Furthermore, it was found that melatonin (MT) might prevent retinal neurons of pyroptosis via NF-κ B/NLRP3 axis after HIOP injury in rats. CONCLUSION: Melatonin treatment might be considered a new strategy for protecting retinal neurons against pyroptosis following acute HIOP injury.

A Chemotherapy-Driven Increase in Mcl-1 Mediates the Effect of miR-375 on Cisplatin Resistance in Osteosarcoma Cells.

BACKGROUND: Osteosarcoma (OS) is one of the most difficult cancers to treat due to its resistance to chemotherapy. The essential role played by Mcl-1 in promoting chemoresistance has been observed in a variety of cancers, including OS, while the underlying mechanism remains unclear. METHODS: We investigated the expression of Mcl-1 in 42 paired OS specimens obtained before and after adjuvant chemotherapy, and its correlation with clinicopathological characteristics. Loss and gain of function studies were performed to analyze the effects of Mcl-1 modulations on the chemosensitivity, and the mechanism involved in the deregulation of Mcl-1 in OS cells. RESULTS: In OS specimens, the expression of Mcl-1 was significantly upregulated after chemotherapy, and high Mcl-1 expression was associated with poorer overall survival and an increased recurrence rate. Furthermore, we demonstrated that chemotherapy-driven increased Mcl-1 decreased chemosensitivity by promoting tumour proliferation and inhibiting DNA damage. Moreover, Mcl-1 was found to be a direct target of miR-375 in OS cells. The knockdown of Mcl-1 phenocopied miR-375 downregulation, and the overexpression of miR-375 rescued the effects of cisplatin-induced DNA damage mediated by Mcl-1. CONCLUSION: Our data indicated that chemotherapy-driven increase in the expression of Mcl-1 plays a critical role in chemoresistance, and the intervention of the miR-375/Mcl-1 axis may offer a novel strategy to enhance chemosensitivity in OS treatment.