Ischemia/reperfusion injury (I/R) is one of the leading causes of acute kidney injury (AKI) that typically occurs in renal surgeries. However, renal I/R still currently lacks effective therapeutic targets. In this study, we proved that inhibition of Brd4 with its selective inhibitor, JQ1, could exert a protective role in renal I/R injury in mice. Inhibiting Brd4 with either JQ1 or genetic knockdown resulted in reduction of endoplasmic reticulum stress (ERS)-associated protein and proapoptotic protein expression both in I/R-induced injury and hypoxia/reoxygenation (H/R) stimulation in HK-2 cells. H/R-induced apoptosis and ERS depended on oxidative stress in vitro. Moreover, FoxO4, which is involved in the generation of hydrogen peroxide, was up-regulated during H/R stimulation-mediated apoptosis and ERS, and this upregulation could be abolished by Brd4 inhibition. Consistently, FoxO4-mediated ROS generation was attenuated upon inhibition of Brd4 with JQ1 or siRNA against Brd4. Further, the transcriptional activity of FoxO4 was suppressed by PI3K and AKT phosphorylation, which are upstream signals of FoxO4 expression, and were enhanced by Brd4 both in vivo and in vitro. In conclusion, our results proved that Brd4 inhibition blocked renal apoptotic and ERS protein expression by preventing FoxO4-dependent ROS generation through the PI3K/AKT pathway, indicating that Brd4 could be a potential therapeutic target for renal I/R injury.

Background. Extensive evidence has demonstrated that oxidative stress, pyroptosis, and proinflammatory programmed cell death are related to renal ischemia/reperfusion (I/R) injury. However, the underlying mechanism remains to be illustrated. Protein arginine methylation transferase 5 (PRMT5), which mediates arginine methylation involved in the regulation of epigenetics, exhibits a variety of biological functions and essential roles in diseases. The present study investigated the role of PRMT5 in oxidative stress and pyroptosis induced by I/R injury in a mouse model and in a hypoxia/reoxygenation (H/R) model of HK-2 cells. Methods. C57 mice were used as an animal model. All mice underwent right nephrectomy, and the left renal pedicles were either clamped or not. Renal I/R injury was induced by ligating the left renal pedicle for 30 min followed by reperfusion for 24 h. HK-2 cells were exposed to normal conditions or stimulation through H/R. EPZ015666(EPZ)—a selective potent chemical inhibitor—and small interfering RNA (siRNA) were administered to suppress the function and expression of PRMT5. The levels of urea nitrogen and creatinine in the serum and renal tissue injury were assessed. Immunohistochemistry, western blotting, and reverse transcription-polymerase chain reaction were used to evaluate pyroptosis-related proteins including nod-like receptor protein-3, ASC, caspase-1, caspase-11, GSDMD-N, and interleukin-1β. Cell apoptosis and cell viability were detected through flow cytometry, and the levels of reactive oxygen species (ROS) and hydrogen peroxide (H₂O₂) were measured. Ki-67 was used to assess the proliferation of renal tubular epithelium. In addition, the activity of malondialdehyde and superoxide dismutase was determined. Results. I/R or H/R induced an increase in the expression of PRMT5. Inhibition of PRMT5 by EPZ alleviated oxidative stress and I/R- or H/R-induced pyroptosis. In renal tissue, the application of EPZ promoted the proliferation of tubular epithelium. In addition, H/R-induced pyroptosis in HK-2 cells was dependent on oxidative stress in vitro. Administration of either EPZ or siRNA led to decreased expression of pyroptosis-related proteins. Inhibition of PRMT5 also attenuated the I/R- or H/R-induced oxidative stress in vivo and in HK-2 cells, respectively. It also resulted in a distinct decrease in the levels of malondialdehyde and H₂O₂, and an apparent increase in superoxide dismutase activity in mouse renal tissue. Moreover, it led to a significant decrease in the levels of ROS and H₂O₂ in HK-2 cells. When activated, NF-E2-related factor/heme oxygenase-1 (Nrf2/HO-1)—a key regulator of various cytoprotective proteins that withstand oxidative damage—can decrease the generation of ROS. Nrf2/HO-1 was downregulated during I/R in tissues and H/R in HK-2 cells, and this effect was reversed by the PRMT5 inhibitor. Furthermore, the expressions of Nrf2 and HO-1 proteins were markedly upregulated by EPZ or siRNA against PRMT5. Conclusion. PRMT5 is involved in ischemia- and hypoxia-induced oxidative stress and pyroptosis in vitro and in vivo. Inhibition of PRMT5 may ameliorate renal I/R injury by suppressing oxidative stress and pyroptosis via the activation of the Nrf2/HO-1 pathway, as well as promoting the proliferation of tubular epithelium. Therefore, PRMT5 may be a promising therapeutic target.

Endoplasmic reticulum (ER) stress, pyroptosis, and apoptosis are critical molecular events in the occurrence and progress of renal ischemia reperfusion (I/R) injury. Naringenin (4′,5,7‐trihydroxyflavanone) is one of the most widely consumed flavonoids with powerful antioxidant and anti‐inflammatory activities. However, whether naringenin is able to relieve renal I/R injury and corresponding mechanisms have not been fully clarified. This study was aimed at exploring its role and relevant mechanisms in renal I/R injury. The C57Bl/6 mice were randomly assigned to receive administration with naringenin (50 mg/kg/d) or sterile saline (1.0 mL/d) for 3 d by gavage and suffered from renal I/R surgery. One specific ER stress inhibitor, 4‐phenylbutyric acid (4‐PBA, 100 mg/kg/d), was intraperitoneally administered to validate the regulation of ER stress on pyroptosis and apoptosis. Cultured HK‐2 cells went through the process of hypoxia/reoxygenation (H/R) to perform cellular experiments with the incubation of naringenin (200 μM), 4‐PBA (5 mM), or brusatol (400 nM). The animal results verified that naringenin obviously relieved renal I/R injury, while it refined renal function and attenuated tissue structural damage. Furthermore, naringenin treatment inhibited I/R‐induced ER stress as well as pyroptosis and apoptosis as indicated by decreased levels of specific biomarkers such as GRP78, CHOP, caspase‐12, NLRP3, ASC, caspase‐11, caspase‐4, caspase‐1, IL‐1β, GSDMD‐N, BAX, and cleaved caspase‐3 in animals and HK‐2 cells. Besides, the upregulated expression of Nrf2 and HO‐1 proteins after naringenin treatment suggested that naringenin activated the Nrf2/HO‐1 signaling pathway, which was again authenticated by the usage of brusatol (Bru), one unique inhibitor of the Nrf2 pathway. Importantly, the application of 4‐PBA showed that renal I/R‐generated pyroptosis and apoptosis were able to be regulated by ER stress in vivo and in vitro. In conclusion, naringenin suppressed ER stress by activating Nrf2/HO‐1 signaling pathway and further alleviated pyroptosis and apoptosis to protect renal against I/R injury.

Disulfidptosis is a newly discovered mode of cell death induced by disulfide stress. However, the prognostic value of disulfidptosis-related genes (DRGs) in renal cell carcinoma (RCC) remains to be further elucidated. In this study, consistent cluster analysis was used to classify 571 RCC samples into three DRG-related subtypes based on changes in DRGs expression. Through univariate regression analysis and LASSO-Cox regression analysis of differentially expressed genes (DEGs) among three subtypes, we constructed and validated a DRG risk score to predict the prognosis of patients with RCC, while also identifying three gene subtypes. Analysis of DRG risk score, clinical characteristics, tumor microenvironment (TME), somatic cell mutations, and immunotherapy sensitivity revealed significant correlations between them. A series of studies have shown that MSH3 can be a potential biomarker of RCC, and its low expression is associated with poor prognosis in patients with RCC. Last but not least, overexpression of MSH3 promotes cell death in two RCC cell lines under glucose starvation conditions, indicating that MSH3 is a key gene in the process of cell disulfidptosis. In summary, we identify potential mechanism of RCC progression through DRGs -related tumor microenvironment remodeling. In addition, this study has successfully established a new disulfidptosis-related genes prediction model and discovered a key gene MSH3. They may be new prognostic biomarkers for RCC patients, provide new insights for the treatment of RCC patients, and may inspire new methods for the diagnosis and treatment of RCC patients.

(1) Background: Early diagnosis and treatment are essential to reduce the mortality rate of bladder cancer (BLCA). We aimed to develop deep learning (DL)-based weakly supervised models for the diagnosis of BLCA and prediction of overall survival (OS) in muscle-invasive bladder cancer (MIBC) patients using whole slide digitized histological images (WSIs). (2) Methods: Diagnostic and prognostic models were developed using 926 WSIs of 412 BLCA patients from The Cancer Genome Atlas cohort. We collected 250 WSIs of 150 BLCA patients from the Renmin Hospital of Wuhan University cohort for external validation of the models. Two DL models were developed: a BLCA diagnostic model (named BlcaMIL) and an MIBC prognostic model (named MibcMLP). (3) Results: The BlcaMIL model identified BLCA with accuracy 0.987 in the external validation set, comparable to that of expert uropathologists and outperforming a junior pathologist. The C-index values for the MibcMLP model on the internal and external validation sets were 0.631 and 0.622, respectively. The risk score predicted by MibcMLP was a strong predictor independent of existing clinical or histopathologic indicators, as demonstrated by univariate Cox (HR = 2.390, p < 0.0001) and multivariate Cox (HR = 2.414, p < 0.0001) analyses. The interpretability of DL models can help in the analysis of critical regions associated with tumors to enrich the information obtained from WSIs. Furthermore, the expression of six genes (ANAPC7, MAPKAPK5, COX19, LINC01106, AL161431.1 and MYO16-AS1) was significantly associated with MibcMLP-predicted risk scores, revealing possible potential biological correlations. (4) Conclusions: Our study developed DL models for accurately diagnosing BLCA and predicting OS in MIBC patients, which will help promote the precise pathological diagnosis of BLCA and risk stratification of MIBC to improve clinical treatment decisions.

Energy stress is an unfavorable condition that tumor cells are often exposed to. Ferroptosis is considered an emerging target for tumor therapy. However, the role of ferroptosis in energy stress in renal cancer is currently unknown. In this study, we found that glucose deprivation significantly enhanced GPX4‐dependent ferroptosis through AMPK activation. Further, AMPK activation suppressed GPX4 expression at the transcriptional level through the upregulation of P53 expression. Additionally, the inactivation of JAK2/STAT3 transcriptionally promoted P53 expression, thereby promoting AMPK‐mediated GPX4‐dependent ferroptosis. In conclusion, energy stress promotes AMPK‐mediated GPX4‐dependent erastin‐induced ferroptosis in renal cancer through the JAK2/STAT3/P53 signaling axis.