Small cell lung cancer (SCLC) is characterized by rapid development of chemoresistance and poor outcomes. Cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) are widely used in breast cancer and other cancer types. However, the molecular mechanisms of CDK4/6 in SCLC chemoresistance remain poorly understood. Here, Rb1flox/flox, Trp53flox/flox, Ptenflox/flox (RTP) and Rb1flox/flox, Trp53flox/flox, MycLSL/LSL (RPM) spontaneous SCLC mouse models, SCLC cell line-derived xenograft (CDX) models, and SCLC patient-derived xenograft (PDX) models are established to reveal the potential effects of CDK4/6is on SCLC chemoresistance. In this study, it is found that CDK4/6is palbociclib (PD) or ribociclib (LEE) combined with chemotherapeutic drugs significantly inhibit SCLC tumor growth. Mechanistically, CDK4/6is do not function through the classic Retionblastoma1 (RB) dependent axis in SCLC. CDK4/6is induce impair autophagy through the AMBRA1-lysosome signaling pathway. The upregulated AMBRA1 protein expression leads to CDK6 degradation via autophagy,  and the following TFEB and TFE3 nuclear translocation inhibition leading to the lysosome-related genes levels downregulation. Moreover, it is found that the expression of CDK6 is higher in SCLC tumors than in normal tissue and it is associated with the survival and prognosis of SCLC patients. Finally, these findings demonstrate that combining CDK4/6is with chemotherapy treatment may serve as a potential therapeutic option for SCLC patients.

BACKGROUND: Non-small cell lung cancer (NSCLC) accounts for 85 % of lung cancer, becoming the most mortality of all cancers globally. Blockage of autophagy in NSCLC represents a promising therapeutic strategy that inhibits angiogenesis and overcomes drug resistance. Natural ingredients in anti-tumor adjuvants are increasingly reported to promote cell death with less side effects and the potential to increase chemotherapeutic drugs sensitivity. Baicalin, a Scutellaria baicalensis-extracted flavonoid glycoside, is reported to induce death of NSCLC cells, however, its effects on autophagy in NSCLC cells remain unclear.
OBJECTIVE: This study aimed to investigate the effect of baicalin on autophagic flux in NSCLC cells, unraveling the underlying mechanism including potential target and its role in cell death of NSCLC cells.
METHODS: In vitro anti-cancer effects of baicalin were verified by evaluating proliferation, clone formation, cell cycle, and cell migration in three NSCLC cell lines (A549, H1299, and PC-9). In vivo anti-tumor efficacies of baicalin were evaluated in subcutaneous xenograft tumor model in nude mice. Autophagy characterization in NSCLC cells included autophagic marker detection by western blot and immunofluorescence staining, subcellular structure observation by TEM, lysosomal function by RNA-seq and fluorescence staining (LysoTracker®, LysoSensor®, and acridine orange). Based on RNA-seq and molecular biological verification using apoptotic, autophagic, and lysosomal inhibitors, potential target molecule of baicalin was verified via Ca2+ flux assay, MCOLN3 knockdown by shRNA, and virtual molecular docking.
RESULTS: Baicalin inhibited NSCLC cell proliferation and migration, and suppressed tumor growth in vivo. Baicalin blocked the autophagic flux via activating the membranal cation channel MCOLN3 of lysosome, which disrupted its Ca2+ balance and induced lysosome dysfunction, leading to failure of autolysosome degradation. The cytoplasmic Ca2+ imbalance further resulted in depolarization of mitochondrial membrane potentials and ROS accumulation in NSCLC cells, mediating autophagy-related apoptosis.
CONCLUSIONS: This study demonstrated that baicalin inhibited autolysosome degradation by activating MCOLN3, leading to dysfunction in lysosomal pH elevation, thereby inhibiting autophagy in NSCLC, leading to apoptotic death of NSCLC cells. These findings enriched the existing theories of cancer therapy based on autophagy inhibition and underlying mechanisms of flavonoids as antitumor agents, paving the way for their clinical application in future.

Queen bee acid (QBA), which is exclusively found in royal jelly, has anti-inflammatory, antihypercholesterolemic, and antiangiogenic effects. A recent study demonstrated that QBA enhances autophagic flux in the heart. Considering the significant role of autophagy in the development of myocardial ischemia/reperfusion (I/R) injury, we investigated the effect of pretreatment with QBA on myocardial damage. In an in vivo model, left coronary artery blockage for 30 min and reperfusion for 2 h were used to induce myocardial I/R. In an in vitro model, neonatal rat cardiomyocytes (NRCs) were exposed to 3 h of hypoxia and 3 h of reoxygenation (H/R). Our results showed that pretreatment with QBA increased the cell viability of cardiomyocytes exposed to H/R in a dose-dependent manner, and the best protective concentration of QBA was 100 μM. Next, we noted that QBA pretreatment (24h before H/R) enhanced autophagic flux and attenuated mitochondrial damage, cardiac oxidative stress and apoptosis in NRCs exposed to H/R injury, and these effects were weakened by cotreatment with the autophagy inhibitor bafilomycin A1 (Baf). In addition, similar results were observed when QBA (10 mg/kg) was injected intraperitoneally into I/R mice 30 min before ischemia. Compared to mice subjected to I/R alone, those treated with QBA had decreased myocardial infarct area and increased cardiac function, whereas, these effects were partly reversed by Baf. Notably, in NRCs exposed to H/R, tandem fluorescent mRFP-GFP-LC3 assays indicated increased autophagosome degradation due to the increase in autophagic flux upon QBA treatment, but coinjection of Baf blocked autophagic flux. In this investigation, no notable adverse effects of QBA were detected in either cellular or animal models. Our findings suggest that QBA pretreatment mitigates myocardial I/R injury by eliminating dysfunctional mitochondria and reducing reactive oxygen species via promoting autophagic flux.

Ischemic stroke is one of the most disabling and fatal diseases around the world. The damaged brain tissues will undergo excessive autophagy, vascular endothelial cells injury, blood-brain barrier (BBB) impairment and neuroinflammation after ischemic stroke. However, there is no unified viewpoint on the underlying mechanism of brain damage. Transforming growth factor-β1 (TGF-β1), as a multi-functional cytokine, plays a crucial role in the intricate pathological processes and helps maintain the physiological homeostasis of brain tissues through various signaling pathways after ischemic stroke. In this review, we summarize the protective role of TGF-β1 in autophagic flux, BBB, vascular remodeling, neuroinflammation and other aspects after ischemic stroke. Based on the review, we believe that TGF-β1 could serve as a key target for treating ischemic stroke.

BACKGROUND: Dexmedetomidine (DEX), a highly selective α2-adrenergic receptor agonist, is widely used for sedation and anesthesia in patients undergoing hepatectomy. However, the effect of DEX on autophagic flux and liver regeneration remains unclear.
OBJECTIVE: This study aimed to determine the role of DEX in hepatocyte autophagic flux and liver regeneration after PHx.
METHODS: In mice, DEX was intraperitoneally injected 5 min before and 6 h after PHx. In vitro, DEX was co-incubated with culture medium for 24 h. Autophagic flux was detected by LC3-II and SQSTM1 expression levels in primary mouse hepatocytes and the proportion of red puncta in AML-12 cells transfected with FUGW-PK-hLC3 plasmid. Liver regeneration was assessed by cyclinD1 expression, Edu incorporation, H&E staining, ki67 immunostaining and liver/body ratios. Bafilomycin A1, si-GSK3β and Flag-tagged GSK3β, α2-ADR antagonist, GSK3β inhibitor, AKT inhibitor were used to identify the role of GSK3β in DEX-mediated autophagic flux and hepatocyte proliferation.
RESULTS: Pre- and post-operative DEX treatment promoted liver regeneration after PHx, showing 12 h earlier than in DEX-untreated mice, accompanied by facilitated autophagic flux, which was completely abolished by bafilomycin A1 or α2-ADR antagonist. The suppression of GSK3β activity by SB216763 and si-GSK3β enhanced the effect of DEX on autophagic flux and liver regeneration, which was abolished by AKT inhibitor.
CONCLUSIONS: Pre- and post-operative administration of DEX facilitates autophagic flux, leading to enhanced liver regeneration after partial hepatectomy through suppression of GSK3β activity in an α2-ADR-dependent manner.

Autophagy is an intracellular clearance and recycling pathway that delivers different types of cargos to lysosomes for degradation. In recent years, autophagy has attracted considerable medical interest, and many different techniques are being developed to study this process in experimental models such as Dictyostelium. Here we describe the use of different autophagic markers in confocal microscopy, in vivo and also in fixed cells. In particular, we describe the use of the GFP-Atg8-RFP-Atg8ΔG marker and the optimization of the GFP-PgkA cleavage assay to detect small differences in autophagy flux.

OBJECTIVE: Our previous research discovered that cinnamamide derivatives are a new type of potential cardioprotective agents myocardial ischemia-reperfusion (MIR) injury, among which Compound 10 exhibits wonderful beneficial action in vitro. However, the exact mechanism of Compound 10 still needs to be elucidated.
METHODS: The protective effect of Compound 10 was determined by detecting the cell viability and LDH leakage rate in H9c2 cells subjected to H2O2. Alterations of electrocardiogram, echocardiography, cardiac infarct area, histopathology and serum myocardial zymogram were tested in MIR rats. Additionally, the potential mechanism of Compound 10 was explored through PCR. Network pharmacology and Western blotting was conducted to monitor levels of proteins related to autophagic flux and mTOR, autophagy regulatory substrate, induced by Compound 10 both in vitro and in vivo, as well as expressions of Sirtuins family members.
RESULTS: Compound 10 significantly ameliorated myocardial injury, as demonstrated by increased cell viability, decreased LDH leakage in vitro, and declined serum myocardial zymogram, ST elevation, cardiac infarct area and improved cardiac function and microstructure of heart tissue in vivo. Importantly, Compound 10 markedly enhanced the obstruction of autophagic flux and inhibited excessive autophagy initiation against MIR by decreased ATG5, Rab7 and increased P-mTOR and LAMP2. Furthermore, Sirt1 knockdown hindered Compound 10\'s regulation on mTOR, leading to interrupted cardiac autophagic flux.
CONCLUSIONS: Compound 10 exerted cardioprotective effects on MIR by reducing excessive autophagy and improving autophgic flux blockage. Our work would take a novel insight in seeking effective prevention and treatment strategies against MIR injury.

Hernandezine (Her), a bisbenzylisoquinoline alkaloid extracted from Thalictrum flavum, is recognized for its range of biological activities inherent to this herbal medicine. Despite its notable properties, the anti-cancer effects of Her have remained largely unexplored. In this study, we elucidated that Her significantly induced cytotoxicity in cancer cells through the activation of apoptosis and necroptosis mechanisms. Furthermore, Her triggered autophagosome formation by activating the AMPK and ATG5 conjugation systems, leading to LC3 lipidation. Our findings revealed that Her caused damage to the mitochondrial membrane, with the damaged mitochondria undergoing mitophagy, as evidenced by the elevated expression of mitophagy markers. Conversely, Her disrupted autophagic flux, demonstrated by the upregulation of p62 and accumulation of autolysosomes, as observed in the RFP-GFP-LC3 reporter assay. Initially, we determined that Her did not prevent the fusion of autophagosomes and lysosomes. However, it inhibited the maturation of cathepsin D and increased lysosomal pH, indicating an impairment of lysosomal function. The use of the early-stage autophagy inhibitor, 3-methyladenine (3-MA), did not suppress LC3II, suggesting that Her also induces noncanonical autophagy in autophagosome formation. The application of Bafilomycin A1, an inhibitor of noncanonical autophagy, diminished the recruitment of ATG16L1 and the accumulation of LC3II by Her, thereby augmenting Her-induced cell death. These observations imply that while autophagy initially plays a protective role, the disruption of the autophagic process by Her promotes programmed cell death. This study provides the first evidence of Her\'s dual role in inducing apoptosis and necroptosis while also initiating and subsequently impairing autophagy to promote apoptotic cell death. These insights contribute to a deeper understanding of the mechanisms underlying programmed cell death, offering potential avenues for enhancing cancer prevention and therapeutic strategies.

Chickens are a major source of meat and eggs in human food and have significant economic value. Cadmium (Cd) is a common environmental pollutant that can contaminate feed and drinking water, leading to kidney injury in livestock and poultry, primarily by inducing the generation of free radicals. It is necessary to develop potential medicines to prevent and treat Cd-induced nephrotoxicity in poultry. Luteolin (Lut) is a natural flavonoid compound mainly extracted from peanut shells and has a variety of biological functions to defend against oxidative damage. In this study, we aimed to demonstrate whether Lut can alleviate kidney injury under Cd exposure and elucidate the underlying molecular mechanisms. Renal histopathology and cell morphology were observed. The indicators of renal function, oxidative stress, DNA damage and repair, NAD+ content, SIRT1 activity, and autophagy were analyzed. In vitro data showed that Cd exposure increased ROS levels and induced oxidative DNA damage and repair, as indicated by increased 8-OHdG content, increased γ-H2AX protein expression, and the over-activation of the DNA repair enzyme PARP-1. Cd exposure decreased NAD+ content and SIRT1 activity and increased LC3 II, ATG5, and particularly p62 protein expression. In addition, Cd-induced oxidative DNA damage resulted in PARP-1 over-activation, reduced SIRT1 activity, and autophagic flux blockade, as evidenced by reactive oxygen species scavenger NAC application. The inhibition of PARP-1 activation with the pharmacological inhibitor PJ34 restored NAD+ content and SIRT1 activity. The activation of SIRT1 with the pharmacological activator RSV reversed Cd-induced autophagic flux blockade and cell injury. In vivo data demonstrated that Cd treatment caused the microstructural disruption of renal tissues, reduced creatinine, and urea nitrogen clearance, raised MDA content, and decreased the activities or contents of antioxidants (GSH, T-SOD, CAT, and T-AOC). Cd treatment caused oxidative DNA damage and PARP-1 activation, decreased NAD+ content, decreased SIRT1 activity, and impaired autophagic flux. Notably, the dietary Lut supplement observably alleviated these alterations in chicken kidney tissues induced by Cd. In conclusion, the dietary Lut supplement alleviated Cd-induced chicken kidney injury through its potent antioxidant properties by relieving the oxidative DNA damage-activated PARP-1-mediated reduction in SIRT1 activity and repairing autophagic flux blockade.

Nine jatrophane diterpenoids were isolated from the whole plant Euphorbia helioscopia, including two new ones, helioscopnins A (1) and B (2). Comprehensive spectroscopic data analysis and ECD calculations elucidated their structures, including absolute configurations. All compounds were evaluated for bioactivity towards autophagic flux by flow cytometry using HM mCherry-GFP-LC3 cells. Compounds 1, 3, 4, 5, 8, and 9 significantly increased autophagic flux.