Ferroptosis is a distinct iron-dependent mechanism of regulated cell death recognized in cancer and ischemia/reperfusion (I/R) injury of different organs. It has been reported that molecules such as liproxstatin-1 (Lip-1) inhibit ferroptosis and promote cell survival however, the mechanisms underlying this action are not clearly understood. We investigated the role and mechanism of Lip-1 in reducing cell death in the ischemic myocardium. Using an I/R model of isolated perfused mice hearts in which Lip-1 was given at the onset of reperfusion, we found that Lip-1 protects the heart by reducing myocardial infarct sizes and maintaining mitochondrial structural integrity and function. Further investigation revealed that Lip-1-induced cardioprotection is mediated by a reduction of VDAC1 levels and oligomerization, but not VDAC2/3. Lip-1 treatment also decreased mitochondrial reactive oxygen species production and rescued the reduction of the antioxidant GPX4 caused by I/R stress. Meanwhile, mitochondrial Ca²⁺ retention capacity needed to induce mitochondrial permeability transition pore opening did not change with Lip-1 treatment. Thus, we report that Lip-1 induces cardioprotective effects against I/R injury by reducing VDAC1 levels and restoring GPX4 levels.

Doxorubicin (DOX) is an anthracycline drug with a wide spectrum of clinical antineoplastic activity, but increased apoptosis has been implicated in its cardiotoxicity. Resveratrol (RES) was shown to harbour major health benefits in diseases associated with oxidative stress. In this study, we aimed to determine the effect of RES on DOX-induced myocardial apoptosis in mice. Male Balb/c mice were randomized to one of the following four treatments: saline, RES, DOX, or RES plus DOX (10 mice in each group). DOX treatment markedly depressed cardiac function, decreased the heart weight, the body weight, and the ratio of heart weight to body weight, but inversely increased the level of protein carbonyl, malondialdehyde, and serum lactate dehydrogenase, and induced mitochondrial cytochrome c release and cardiomyocyte apoptosis. However, these effects of DOX were ameliorated by its combination with RES. Further studies with a co-immunoprecipitation assay revealed an interaction between p53 and Sirtuin 1 (SIRT1). It was found by western blot and electrophoretic mobility shift assay that DOX treatment increased p53 protein acetylation and cytochrome c release from mitochondria, activated p53 binding at the Bax promoter, and up-regulated Bax expression, but supplementation with RES could weaken all these effects. The protective effect of RES against DOX-induced cardiomyocyte apoptosis is associated with the up-regulation of SIRT1-mediated p53 deacetylation.

Background and Purpose: Recent evidence indicates that GPER (G protein‐coupled oestrogen receptor 1) mediates acute pre‐ischaemic oestrogen‐induced protection of the myocardium from ischaemia/reperfusion injury via a signalling cascade that includes PKC translocation, ERK1/2/ GSK‐3β phosphorylation and inhibition of the mitochondrial permeability transition pore (mPTP) opening. Here, we investigated the impact and mechanism involved in post‐ischaemic GPER activation in ischaemia/reperfusion injury. We determined whether GPER activation at the onset of reperfusion confers cardioprotective effects by protecting against mitochondrial impairment and mitophagy.Experimental Approach: In vivo rat hearts were subjected to ischaemia followed by reperfusion with oestrogen (17β‐oestradiol, E2), E2 + G15, a GPER antagonist, or vehicle. Myocardial infarct size, the threshold for the opening of mPTP, mitophagy, mitochondrial membrane potential, ROS production, proteins ubiquitinated including cyclophilin D, and phosphorylation levels of ERK and GSK‐3β were measured.Results: We found that post‐ischaemic E2 administration to both male and female ovariectomized‐rats reduced myocardial infarct size. Post‐ischaemic E2 administration preserved mitochondrial structural integrity and this was associated with a decrease in ROS production and increased mitochondrial membrane potential, as well as an increase in the mitochondrial Ca²⁺ load required to induce mPTP opening via activation of the MEK/ERK/GSK‐3β axis. Moreover, E2 reduced mitophagy via the PINK1/Parkin pathway involving LC3I, LC3II and p62 proteins. All these post‐ischaemic effects of E2 were abolished by G15 suggesting a GPER‐dependent mechanism.Conclusion: These results indicate that post‐ischaemic GPER activation induces cardioprotective effects against ischaemia/reperfusion injury in males and females by protecting mitochondrial structural integrity and function and reducing mitophagy.

The aberrant expression of microRNAs (miRNAs) is associated with colorectal carcinogenesis, but the underlying mechanisms are not clear. This study showed that the miRNA-27a (miR-27a) was significantly reduced in colorectal cancer tissues and colorectal cancer cell lines, and that the reduced miR-27a was associated with distant metastasis and colorectal cancer clinical pathological stages–miR-27a was lower at stages III/IV than that at stage II. Bioinformatic and systemic biological analysis predicted several targets of miR-27a, among them SGPP1 and Smad2 were significantly affected. SGPP1 and Smad2 at mRNA and protein levels were negatively correlated with miR-27a in human colorectal cancer tissues and cancer cell lines. Increased miR-27a significantly repressed SGPP1 and Smad2 at transcriptional and translational levels. Functional studies showed that increasing miR-27a inhibited colon cancer cell proliferation, promoted apoptosis and attenuated cell migration, which were also linked to downregulation of p-STAT3 and upregulation of cleaved caspase 3. In vivo, miR-27a inhibited colon cancer cell growth in tumor-bearing mice. Taken together, this study has revealed miR-27a as a tumor suppressor and has identified SGPP1 and Smad2 as novel targets of miR-27a, linking to STAT3 for regulating cancer cell proliferation, apoptosis and migration in colorectal cancer. Therefore, miR-27a could be a useful biomarker for monitoring colorectal cancer development and progression, and also could have a therapeutic potential by targeting SGPP1, Smad2 and STAT3 for colorectal cancer therapy.

Mitofilin is an inner membrane protein that has been defined as a mitochondria-shaping protein in controlling and maintaining mitochondrial cristae structure and remodeling. We determined the role of mitofilin in cell survival by investigating the mechanism underlying mitofilin knockdown-induced cell death by apoptosis. Cultured H9c2 myoblasts and HEK 293 cells were treated with mitofilin siRNA or scrambled siRNA for 24 h. Cell death (apoptosis), caspase 3 activity and cell cycle phases were assessed by flow cytometry, while cytochrome c release and intracellular ATP production were measured by ELISA. Mitofilin, apoptosis-inducing factor (AIF) and poly(ADP-ribose) polymerase (PARP) expression were measured by Western blot analysis and calpain activity was assessed using a calpain activity kit. Mitochondrial images were taken using electron microscopy. We found that mitofilin knockdown increases apoptosis mainly via activation of the AIF-PARP pathway leading to nuclear fragmentation that is correlated with S phase arrest of the cell cycle. Knockdown of mitofilin also led to mitochondrial swelling and damage of cristae that is associated with the increase in reactive oxygen species production and mitochondrial calpain activity, as well as a marked decrease in intracellular ATP production and mitochondrial membrane potential. Together, these results indicate that mitofilin knockdown by siRNA increases calpain activity that presumably leads to mitochondrial structural degradation resulting in a critical reduction of mitochondrial function that is responsible for the increase in cell death by apoptosis via an AIF-PARP mechanism and associated with nuclear fragmentation, and S phase arrest of the cell cycle.

The receptor-interacting protein kinase 3 (RIP3) has been reported to regulate programmed necrosis–necroptosis forms of cell death with important functions in inflammation. We investigated whether RIP3 translocates into mitochondria in response to renal ischemia–reperfusion (I/R) to interact with inner mitochondrial protein (Mitofilin) and promote mtDNA release into the cytosol. We found that release of mtDNA activates the cGAS–STING pathway, leading to increased nuclear transcription of pro-inflammatory markers that exacerbate renal I/R injury. Monolateral C57/6N and RIP3^−/− mice kidneys were subjected to 60 min of ischemia followed by either 12, 24, or 48 h of reperfusion. In WT mice, we found that renal I/R injury increased RIP3 levels, as well as its translocation into mitochondria. We observed that RIP3 interacts with Mitofilin, likely promoting its degradation, resulting in increased mitochondria damage and mtDNA release, activation of the cGAS–STING–p65 pathway, and increased transcription of pro-inflammatory markers. All of these effects observed in WT mice were decreased in RIP3^−/− mice. In HK-2, RIP3 overexpression or Mitofilin knockdown increased cell death by activating the cGAS–STING–p65 pathway. Together, this study point to an important role of the RIP3–Mitofilin axis in the initiation and development of renal I/R injury.