P62 regulates resveratrol-mediated Fas/Cav-1 complex formation and transition from autophagy to apoptosis

Unveiling the potential effects of resveratrol in lung cancer treatment: Mechanisms and nanoparticle-based drug delivery strategies

Lung cancer ranks among the most prevalent forms of cancer and remains a significant factor in cancer-related mortality across the world. It poses significant challenges to healthcare systems and society as a whole due to its high incidence, mortality rates, and late-stage diagnosis. Resveratrol (RV), a natural compound found in various plants, has shown potential as a nanomedicine for lung cancer treatment. RV has varied effects on cancer cells, including promoting apoptosis by increasing pro-apoptotic proteins (Bax and Bak) and decreasing anti-apoptotic proteins (Bcl-2). It also hinders cell proliferation by influencing important signaling pathways (MAPK, mTOR, PI3K/Akt, and Wnt/β-catenin) that govern cancer progression. In addition, RV acts as a potent antioxidant, diminishing oxidative stress and safeguarding cells against DNA damage. However, using RV alone in cancer treatment has drawbacks, such as low bioavailability, lack of targeting ability, and susceptibility to degradation. In contrast, nanoparticle-based delivery systems address these limitations and hold promise for improving treatment outcomes in lung cancer; nanoparticle formulations of RV offer advantages such as improved drug delivery, increased stability, controlled release, and targeted delivery to lung cancer cells. This article will provide an overview of lung cancer, explore the potential of RV as a therapeutic agent, discuss the benefits and challenges of nanoparticle-based drug delivery, and highlight the promise of RV nanoparticles for cancer treatment, including lung cancer. By optimizing these systems for clinical application, future studies aim to enhance overall treatment outcomes and improve the prognosis for lung cancer patients.

Integration of clinical and spatial data to explore lipid metabolism-related genes for predicting prognosis and immune microenvironment in gliomas

Lipid metabolism is crucial to tumor growth and immune microenvironment as well as drug sensitivity in glioma. Identifying prognostic indicators of glioma and elucidating the mechanisms of glioma progression are critical for improving the prognosis of glioma patients. In this study, we investigated the role and prognostic value of metabolism-related genes in glioma by integrative analysis of datasets from GEO, CGGA, and TCGA. Based on clinical data and transcriptome data, we found that the expression pattern of three major pathways related to lipid metabolism is fatty acidhigh-phospholipidhigh-triglyceridelow, which is associated with better prognosis and immune infiltration. The genes involved in these three pathways were used to generate a prognostic model, which showed high stability and efficiency in the test set and validation set. The spatial transcriptome of glioma patients revealed that the microenvironment of the regions with high expression of risk genes CAV1 and SCD is in a state of hypoxia, EMT, and cell cycle arrest, and thus can be used as markers of metabolic reprogramming in the tumor microenvironment. In the high-risk group, M0 macrophages and M1 macrophages were significantly enriched, and the risk score was significantly correlated with gene mutation and methylation of risk genes. We further performed drug sensitivity screening corresponding to different risk genes. This study provided novel insights into the differential immune microenvironment with different expression patterns of metablism-related genes and highlighted the spatial and temporal synergy of tumor progression and metabolic reprogramming.

Mechanism of Resveratrol-Induced Programmed Cell Death and New Drug Discovery against Cancer: A Review

Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a polyphenol found in grapes, red wine, peanuts, and apples, has been reported to exhibit a wide range of biological and pharmacological properties. In addition, resveratrol has been reported to intervene in multiple stages of carcinogenesis. It has also been known to kill several human cancer cells through programmed cell death (PCD) mechanisms such as apoptosis, autophagy, and necroptosis. However, resveratrol has limitations in its use as an anticancer agent because it is susceptible to photoisomerization owing to its unstable double bond, short half-life, and is rapidly metabolized and eliminated. Trans-(E)-resveratrol is nontoxic, and has several biological and pharmacological activities. However, little is known about the pharmacological properties of the photoisomerized cis-(Z)-resveratrol. Therefore, many studies on resveratrol derivatives and analogues that can overcome the shortcomings of resveratrol and increase its anticancer activity are underway. This review comprehensively summarizes the literature related to resveratrol-induced PCD, such as apoptosis, autophagy, necroptosis, and the development status of synthetic resveratrol derivatives and analogues as novel anticancer drugs.

Resveratrol as a modulatory of apoptosis and autophagy in cancer therapy

Cancer is one of the leading causes of death, with a heavy socio-economical burden for countries. Despite the great advances that have been made in the treatment of cancer, chemotherapy is still the most common method of treatment. However, many side effects, including hepatotoxicity, renal toxicity, and cardiotoxicity, limit the efficacy of conventional chemotherapy. Over recent years, natural products have attracted attention as therapeutic agents against various diseases, such as cancer. Resveratrol (RES), a natural polyphenol occurring in grapes, nuts, wine, and berries, exhibited potential for preventing and treating various cancer types. RES also ameliorates chemotherapy-induced detrimental effects. Furthermore, RES could modulate apoptosis and autophagy as the main forms of cancer cell deaths by targeting various signaling pathways and up/downregulation of apoptotic and autophagic genes. This review will summarize the anti-cancer effects of RES and focus on the fundamental mechanisms and targets for modulating apoptosis and autophagy by RES.

Caveolin-1 scaffolding domain peptide abrogates autophagy dysregulation in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common and fatal form of interstitial lung disease. IPF is characterized by irreversible scarring of the lungs leading to lung function decline. Although the etiology remains poorly understood, dysregulated autophagy in alveolar-epithelial cells (AECs) together with interplay between apoptotic-AECs and proliferative-myofibroblasts have been strongly implicated in IPF pathogenesis. Recent studies have revealed that a caveolin-1-derived 7-mer peptide, CSP7, mitigates established PF at least in part by improving AEC viability. In the present study, we aimed to determine whether and how CSP7 regulates autophagy in fibrotic-lung AECs. We found that p53 and autophagic proteins were markedly upregulated in AECs from mice with single/multi-doses of bleomycin—or silica-induced PF. This was abolished following treatment of PF-mice with CSP7. Further, CSP7 abrogated silica- or bleomycin-induced p53 and autophagy proteins in AECs. Immunoprecipitation further revealed that CSP7 abolishes the interaction of caveolin-1 with LC3BII and p62 in AECs. AEC-specific p53-knockout mice resisted silica- or bleomycin-induced changes in autophagy proteins, or CSP7 treatment. Our findings provide a novel mechanism by which CSP7 inhibits dysregulated autophagy in injured AECs and mitigates existing PF. These results affirm the potential of CSP7 for treating established PF, including IPF and silicosis.

New dawn for cancer cell death: Emerging role of lipid metabolism

BACKGROUND

Resistance to cell death, a protective mechanism for removing damaged cells, is a "Hallmark of Cancer" that is essential for cancer progression. Increasing attention to cancer lipid metabolism has revealed a number of pathways that induce cancer cell death.

SCOPE OF REVIEW

We summarize emerging concepts regarding lipid metabolic reprogramming in cancer that is mainly involved in lipid uptake and trafficking, de novo synthesis and esterification, fatty acid synthesis and oxidation, lipogenesis, and lipolysis. During carcinogenesis and progression, continuous metabolic adaptations are co-opted by cancer cells, to maximize their fitness to the ever-changing environmental. Lipid metabolism and the epigenetic modifying enzymes interact in a bidirectional manner which involves regulating cancer cell death. Moreover, lipids in the tumor microenvironment play unique roles beyond metabolic requirements that promote cancer progression. Finally, we posit potential therapeutic strategies targeting lipid metabolism to improve treatment efficacy and survival of cancer patient.

MAJOR CONCLUSIONS

The profound comprehension of past findings, current trends, and future research directions on resistance to cancer cell death will facilitate the development of novel therapeutic strategies targeting the lipid metabolism.

The functional mechanism of bone marrow-derived mesenchymal stem cells in the treatment of animal models with Alzheimer's disease: crosstalk between autophagy and apoptosis

The transplantation of bone marrow-derived mesenchymal stem cells (BMMSCs) alleviates neuropathology and improves cognitive deficits in animal models with Alzheimer's disease. However, the underlying mechanism remains undefined. Based on meta-analysis and comprehensive review, high-profile studies support the theory that transplanted BMMSCs activate autophagy, as evidenced by the expression levels of signal molecules such as Beclin-1, Atg5, LC3-II, and mTOR. Functional autophagy mitigates neuronal apoptosis, which is reflected by the alterations of IAPs, Bcl-2, caspase-3, and so forth. Moreover, the transplantation of BMMSCs can decrease aberrant amyloid-beta peptides as well as tau aggregates, inhibit neuroinflammation, and stimulate synaptogenesis. There is a signal crosstalk between autophagy and apoptosis, which may be regulated to produce synergistic effect on the preconditioning of stem cells. Forasmuch, the therapeutic effect of transplanted BMMSCs can be enhanced by autophagy and/or apoptosis modulators.

Shedding New Light on Methylmercury-induced Neurotoxicity Through the Crosstalk Between Autophagy and Apoptosis

Methylmercury (MeHg) is a bio-accumulative global environmental contaminant present in fish and seafood. MeHg accumulates in the aquatic environment and eventually reaches the human system via the food chain by bio-magnification. The central nervous system is the primary target of toxicity and is particularly vulnerable during development. It is well documented that developmental MeHg exposure can lead to neurological alterations, including cognitive and motor dysfunction. Apoptosis is a primary characteristic of MeHg-induced neurotoxicity, and may be regulated by autophagic activity. However, mechanisms mediating the interaction between apoptosis and autophagy remains to be explored. Autophagy is an adaptive response under stressful conditions, and the basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy can regulate cell fate through different crosstalk signaling pathways. A complex interplay between autophagy and apoptosis determines the degree of apoptosis and the progression of MeHg-induced neurotoxicity as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances in the roles of autophagy and apoptosis in MeHg neurotoxicity and thoroughly explores the relationship between them. The autophagic pathway may be a potential therapeutic target in MeHg neurotoxicity through modulation of apoptosis.

Novel Balance Mechanism Participates in Stem Cell Therapy to Alleviate Neuropathology and Cognitive Impairment in Animal Models with Alzheimer's Disease

Stem cell therapy improves memory loss and cognitive deficits in animal models with Alzheimer's disease. The underlying mechanism remains to be determined, but it may involve the interaction of stem cells with hippocampal cells. The transplantation of stem cells alters the pathological state and establishes a novel balance based on multiple signaling pathways. The new balance mechanism is regulated by various autocrine and paracrine cytokines, including signal molecules that target (a) cell growth and death. Stem cell treatment stimulates neurogenesis and inhibits apoptosis, which is regulated by the crosstalk between apoptosis and autophagy-(b) Aβ and tau pathology. Aberrant Aβ plaques and neurofibrillary tau tangles are mitigated subsequent to stem cell intervention-(c) inflammation. Neuroinflammation in the lesion is relieved, which may be related to the microglial M1/M2 polarization-(d) immunoregulation. The transplanted stem cells modulate immune cells and shape the pathophysiological roles of immune-related genes such as TREM2, CR1, and CD33-(e) synaptogenesis. The functional reconstruction of synaptic connections can be promoted by stem cell therapy through multi-level signaling, such as autophagy, microglial activity, and remyelination. The regulation of new balance mechanism provides perspective and challenge for the treatment of Alzheimer's disease.

Targeting Drug Chemo-Resistance in Cancer Using Natural Products

Cancer is one of the leading causes of death globally. The development of drug resistance is the main contributor to cancer-related mortality. Cancer cells exploit multiple mechanisms to reduce the therapeutic effects of anticancer drugs, thereby causing chemotherapy failure. Natural products are accessible, inexpensive, and less toxic sources of chemotherapeutic agents. Additionally, they have multiple mechanisms of action to inhibit various targets involved in the development of drug resistance. In this review, we have summarized the basic research and clinical applications of natural products as possible inhibitors for drug resistance in cancer. The molecular targets and the mechanisms of action of each natural product are also explained. Diverse drug resistance biomarkers were sensitive to natural products. P-glycoprotein and breast cancer resistance protein can be targeted by a large number of natural products. On the other hand, protein kinase C and topoisomerases were less sensitive to most of the studied natural products. The studies discussed in this review will provide a solid ground for scientists to explore the possible use of natural products in combination anticancer therapies to overcome drug resistance by targeting multiple drug resistance mechanisms.

Sequestosome 1/p62: A multitasker in the regulation of malignant tumor aggression (Review)

Sequestosome 1 (SQSTM1)/p62 is an adapter protein mainly involved in the transportation, degradation and destruction of various proteins that cooperates with components of autophagy and the ubiquitin-proteasome degradation pathway. Numerous studies have shown that SQSTM1/p62 functions at multiple levels, including involvement in genetic stability or modification, post-transcriptional regulation and protein function. As a result, SQSTM1/p62 is a versatile protein that is a critical core regulator of tumor cell genetic stability, autophagy, apoptosis and other forms of cell death, malignant growth, proliferation, migration, invasion, metastasis and chemoradiotherapeutic response, and an indicator of patient prognosis. SQSTM1/p62 regulates these processes via its distinct molecular structure, through which it participates in a variety of activating or inactivating tumor-related and tumor microenvironment-related signaling pathways, particularly positive feedback loops and epithelial-mesenchymal transition-related pathways. Therefore, functioning as a proto-oncogene or tumor suppressor gene in various types of cancer and tumor-associated microenvironments, SQSTM1/p62 is capable of promoting or retarding malignant tumor aggression, giving rise to immeasurable effects on tumor occurrence and development, and on patient treatment and prognosis.

LC3B/p62-mediated mitophagy protects A549 cells from resveratrol-induced apoptosis

AIMS

Complicated mechanisms in cancer cells have been restricting the medicinal value of resveratrol (Res). The mechanisms by which Res exerts its anti-tumor activity in lung cancer cells have diverged among reports in recent years, whether cells choose to undergo autophagic cell death or apoptosis remains controversial. Yet, whether Res-induced autophagic cell death transforms into apoptosis is still unknown, and by which autophagy regulates programmed cell death is still undefined.

MAIN METHODS

Here, A549 cells were treated with Res to investigate the mechanisms of autophagy and apoptosis using western blot, immunofluorescence staining for LC3B.

KEY FINDINGS

Non-canonical autophagy was induced by Res-treatment in a Beclin-1- and ATG5-independent manner, with apoptosis being activated simultaneously. Autophagy induced by Res was activated by rapamycin with decreased apoptosis, suggesting that autophagy may serve as a protective pathway in cells. Mitophagy was found to be induced by Res using fluorescence co-localization of mitochondria with lysosomes. Subsequently, it was identified that mitophagy was mediated by LC3B/p62 interaction and could be inhibited by LC3B knockout and p62 knockdown following increased apoptosis.

SIGNIFICANCE

In conclusion, the current results demonstrate that Res-induced non-canonical autophagy in A549 lung cancer cells with apoptosis activation simultaneously, while LC3B/p62-mediated mitophagy protects tumor cells against apoptosis, providing novel mechanisms about the critical role of mitophagy in regulating cell fate.

Polyphenol-Mediated Autophagy in Cancer: Evidence of In Vitro and In Vivo Studies

One of the hallmarks of cellular transformation is the altered mechanism of cell death. There are three main types of cell death, characterized by different morphological and biochemical features, namely apoptosis (type I), autophagic cell death (type II) and necrosis (type III). Autophagy, or self-eating, is a tightly regulated process involved in stress responses, and it is a lysosomal degradation process. The role of autophagy in cancer is controversial and has been associated with both the induction and the inhibition of tumor growth. Autophagy can exert tumor suppression through the degradation of oncogenic proteins, suppression of inflammation, chronic tissue damage and ultimately by preventing mutations and genetic instability. On the other hand, tumor cells activate autophagy for survival in cellular stress conditions. Thus, autophagy modulation could represent a promising therapeutic strategy for cancer. Several studies have shown that polyphenols, natural compounds found in foods and beverages of plant origin, can efficiently modulate autophagy in several types of cancer. In this review, we summarize the current knowledge on the effects of polyphenols on autophagy, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of polyphenols for envisioning future therapies employing polyphenols as chemoadjuvants.

Caveolin as a Novel Potential Therapeutic Target in Cardiac and Vascular Diseases: A Mini Review

Caveolin, a structural protein of caveolae, play roles in the regulation of endothelial function, cellular lipid homeostasis, and cardiac function by affecting the activity and biogenesis of nitric oxide, and by modulating signal transduction pathways that mediate inflammatory responses and oxidative stress. In this review, we present the role of caveolin in cardiac and vascular diseases and the relevant signaling pathways involved. Furthermore, we discuss a novel therapeutic perspective comprising crosstalk between caveolin and autophagy.

Resveratrol As A Natural Regulator Of Autophagy For Prevention And Treatment Of Cancer

Resveratrol, as a natural product compound, has been recently attracted much attention for its potent effects on cancer. Cancer is a serious disease threatening human survival and social development. Autophagy is a cellular pathway to realize the metabolic needs of the cell itself and the renewal of some organelles and plays opposing, context-dependent role in tumorigenesis. So the regulation of autophagy is of great significance in the treatment of cancer. p62, as an autophagy adaptor protein, is a preferred target for autophagy and is constantly controlled by constitutive autophagy. As a tumor-suppression mechanism, autophagy deficiency is common in tumors, which results in aberrant accumulation of p62 and activates p62-regulated pathways, such as activation of mTOR in nutrient sensing, and the activation of the Keap1-Nrf2 pathway for antioxidant stress, which are associated with cancer development. In this review, we emphasize that resveratrol can induce autophagy in the treatment of cancer and accelerates the degradation of p62, and then, the mTOR activation is blocked and Nrf2 activation is suppressed. As a result, the multidrug resistance of cancer cells can be reversed by resveratrol.

N-n-Butyl Haloperidol Iodide Ameliorates Oxidative Stress in Mitochondria Induced by Hypoxia/Reoxygenation through the Mitochondrial c-Jun N-Terminal Kinase/Sab/Src/Reactive Oxygen Species Pathway in H9c2 Cells

Both c-Jun N-terminal kinase (JNK) and reactive oxygen species (ROS) play important roles in myocardial ischemia/reperfusion (I/R) injury. Our previous studies suggest that N-n-butyl haloperidol iodide (F2) exerts cardioprotection by reducing ROS production and JNK activation caused by I/R. In this study, we hypothesized that there is a JNK/Sab/Src/ROS pathway in the mitochondria in H9c2 cells following hypoxia/reoxygenation (H/R) that induces oxidative stress in the mitochondria and that F2 exerts mitochondrial protective effects during H/R injury by modulating this pathway. The results showed that H/R induced higher-level ROS in the cytoplasm on the one hand and JNK activation and translocation to the mitochondria by colocalization with Sab on the other. Moreover, H/R resulted in mitochondrial Src dephosphorylation, and subsequently, oxidative stress evidenced by the increase in ROS generation and oxidized cardiolipin in the mitochondrial membranes and by the decrease in mitochondrial superoxide dismutase activity and membrane potential. Furthermore, treatment with a JNK inhibitor or Sab small interfering RNA inhibited the mitochondrial translocation of p-JNK, decreased colocalization of p-JNK and Sab on the mitochondria, and reduced Src dephosphorylation and mitochondrial oxidative stress during H/R. In addition, Src dephosphorylation by inhibitor PP2 increased mitochondrial ROS production. F2, like inhibitors of the JNK/Sab/Src/ROS pathway, downregulated the H/R-induced mitochondrial translocation of p-JNK and the colocalization of p-JNK and Sab on the mitochondria, increased Src phosphorylation, and alleviated the above-mentioned mitochondrial oxidative stress. In conclusion, F2 could ameliorate H/R-associated oxidative stress in mitochondria in H9c2 cells through the mitochondrial JNK/Sab/Src/ROS pathway.

Resveratrol alleviates chemotherapy-induced oogonial stem cell apoptosis and ovarian aging in mice

Chemotherapy-induced ovarian aging not only increases the risk for early menopause-related complications but also results in infertility in young female cancer survivors. Oogonial stem cells have the ability to generate new oocytes and thus provide new opportunities for treating ovarian aging and female infertility. Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a natural phenol derived from plants, that has been shown to have positive effects on longevity and redox flow in lipid metabolism and a preventive function against certain tumors. To evaluate whether resveratrol could promote the repair of oogonial stem cells damage in a busulfan/cyclophosphamide (Bu/Cy)-induced accelerated ovarian aging model, female mice were administered 30 and 100 mg/kg/d resveratrol through a gavage for 2 weeks. We demonstrated that resveratrol (30 mg/kg/d) relieved oogonial stem cells loss and showed an attenuating effect on Bu/Cy-induced oxidative apoptosis in mouse ovaries, which may be attributed to the attenuation of oxidative levels in ovaries. Additionally, we also showed that Res exerted a dose-dependent effect on oogonial stem cells and attenuated H2O2-induced cytotoxicity and oxidative stress injury by activating Nrf2 in vitro. Therefore, resveratrol could be of a potential therapeutic drug used to prevent chemotherapy-induced ovarian aging.

Role of the Death Receptor and Endoplasmic Reticulum Stress Signaling Pathways in Polyphyllin I-Regulated Apoptosis of Human Hepatocellular Carcinoma HepG2 Cells

Polyphyllin has been reported to exhibit anticancer effects against various types of cancer via the proapoptotic signaling pathway. The aim of the present study was to investigate the role of the endoplasmic reticulum stress and death receptor signaling pathways in PPI-induced apoptosis of human hepatocellular carcinoma HepG2 cells. Analysis demonstrated that PPI could significantly inhibit the proliferation and induce apoptosis of HepG2 cells in a dose- and time-dependent manner. Investigation into the molecular mechanism of PPI indicated that PPI notably mediated ER stress activation via IRE-1 overexpression and activation of the caspase-12 to protect HepG2 cells against apoptosis. In addition, PPI markedly induced the expression of death receptors signaling pathways-associated factors, including tumor necrosis factor (TNF) receptor 1/TNF-α and FAS/FASL. Additionally, suppression of the death receptor signaling pathways with a caspase-8 inhibitor, Z-IETD-FMK, revealed an increase in the death rate and apoptotic rate of HepG2 cells. Collectively, the findings of the present study suggested that the ER stress and death receptor signaling pathways were associated with PPI-induced HepG2 cell apoptosis; however, endoplasmic reticulum stress may serve a protective role in this process. The combination of PPI and Z-IETD-FMK may activate necroptosis, which enhances apoptosis. Therefore, the results of the present study may improve understanding regarding the roles of signaling pathways in PPI regulated apoptosis and contribute to the development of novel therapies for the treatment of HCC.

Grape skin extract improves muscle function and extends lifespan of a Drosophila model of Parkinson's disease through activation of mitophagy

Recent studies suggest that moderate red wine consumption may confer several health benefits, including protection against heart disease, certain cancers and multiple age-related neurological diseases such as Alzheimer's disease. These health benefits are assumed to come from a compound from grape skin called resveratrol, which has been proposed to be a pro-longevity agent. Whether resveratrol accounts for all the health benefits of grape-derived nutrients and the molecular and cellular mechanisms underlying the beneficial effects of such nutrients are not well understood. Here we investigated the effect of supplementing grape skin extract (GSE) left from red wine-production process to the daily food intake of a Drosophila melanogaster model of Parkinson's disease (PD) associated with PTEN-induced kinase 1 (PINK1) loss-of-function. Consumption of GSE resulted in rescue of mitochondrial morphological defects, improvement of indirect flight muscle function and health-span, and prolonged lifespan of the PINK1 mutant flies. Further biochemical and genetic studies revealed a link between activation of mitophagy and the beneficial effects of GSE. Our results indicate that GSE can promote autophagy activation, preserve mitochondria function, and protect against PD pathogenesis, and that the beneficial effect of GSE in mitophagy activation is not accounted for by resveratrol alone.

Graphene oxide induces p62/SQSTM-dependent apoptosis through the impairment of autophagic flux and lysosomal dysfunction in PC12 cells

Graphene oxide (GO), as a two-dimensional carbon nanosheet, has been extensively studied for potential biomedical applications due to its notable properties. Although a growing number of studies have investigated the adverse effects of GO nanosheets, the available toxicity data concerning GO's effect on the neuronal cells remain highly limited. In this work, we systematically investigated the toxic responses of commercially available GO on a rat pheochromocytoma-derived PC12 cell line, which was an ideal in vitro model to study the neurotoxicity of GO. GO exerted a significant toxic effect on PC12 cells in a dose- and time-dependent manner. GO treatments under doses of 40, 50, and 60 μg/mL triggered an autophagic response and the blockade of autophagic flux via disrupting lysosome degradation capability. Caspase 9-mediated apoptosis was also observed in GO-treated cells. Moreover, GO-induced apoptosis was relevant to the aberrant accumulation of autophagy substrate p62/SQSTM. Inhibitionofthe accumulation of autophagic substrate alleviated GO-caused apoptotic cell death. Our findings raise a concern for the putative biomedical applications of GO in the form of diagnostic and therapeutic tools, where its systematic biocompatibility should be thoroughly explored. STATEMENT OF SIGNIFICANCE: Graphene oxide (GO) has attracted considerable interests in biomedical fields, which also resulted in numerous safety risks to human bodies. It is urgently required to establish a paradigm for accurately evaluating their adverse effects in biological systems. This study thoroughly explored the neurotoxicity of GO in PC12 cells. We found GO triggered an increased autophagic response and the impairment of autophagic flux, which was functionally involved in cell apoptosis. Inhibitionofexcessive accumulation of autophagic cargo attenuated apoptotic cell death. Our findings highlight deep considerations on the regulation mechanism of autophagy-lysosomes-apotosis-axis, which will contribute to a better understanding of the neurotoxicity of graphene-family nanomaterials, and provide a new insight in the treatment of cancer cells at nanoscale levels.

Resveratrol induces autophagy-dependent apoptosis in HL-60 cells

BACKGROUND

All known mechanisms of apoptosis induced by resveratrol act through cell cycle arrest and changes in mitochondrial membrane potential. It is currently unknown whether resveratrol-induced apoptosis is associated with other physiological processes, such as autophagy.

METHODS

Apoptosis-related markers involved in the intrinsic and extrinsic apoptotic pathways, and autophagic markers were detected by using western blotting and immunofluorescence. Mitochondrial membrane potential was assayed by flow cytometry. Pharmaceutical or genetic inhibition of autophagy involved were carried by 3- methyladenine or knockdown of autophagy-related (Atg) genes by siRNA. Differences between two values were tested by Student's unpaired t test.

RESULTS

We show that resveratrol-induced apoptosis occurs through both the intrinsic and extrinsic apoptotic pathways. Mitochondrial membrane potential and apoptosis-related markers, such as an increased Bax/Bcl-2 ratio, and cleaved forms of caspase-8 and caspase-3, arise following resveratrol addition. Moreover, we find that resveratrol increases both the levels of microtubule-associated protein 1 light chain 3-II and the number of autophagosomes, and further demonstrate that resveratrol-induced autophagy depends on the LKB1-AMPK-mTOR pathway. We next reveal that some apoptosis-related markers induced by resveratrol are further attenuated by the inhibition of autophagy with 3-methyladenine or knockdown of autophagy-related (Atg) genes by siRNA.

CONCLUSIONS

These results suggest that resveratrol induced apoptotic cell death of HL-60 cells depends on the autophagy activated through both the LKB1-AMPK and PI3K/AKT-regulated mTOR signaling pathways.

Caveolin-1, cancer and therapy resistance

Resistance of solid tumors to chemo- and radiotherapy remains a major obstacle in anti-cancer treatment. Herein, the membrane protein caveolin-1 (CAV1) came into focus as it is highly expressed in many tumors and high CAV1 levels were correlated with tumor progression, invasion and metastasis, and thus a worse clinical outcome. Increasing evidence further indicates that the heterogeneous tumor microenvironment, also known as the tumor stroma, contributes to therapy resistance resulting in poor clinical outcome. Again, CAV1 seems to play an important role in modulating tumor host interactions by promoting tumor growth, metastasis, therapy resistance and cell survival. However, the mechanisms driving stroma-mediated tumor growth and radiation resistance remain to be clarified. Understanding these interactions and thus, targeting CAV1 may offer a novel strategy for preventing cancer therapy resistance and improving clinical outcomes. In this review, we will summarize the resistance-promoting effects of CAV1 in tumors, and emphasize its role in the tumor-stroma communication as well as the resulting malignant phenotype of epithelial tumors.

Metformin potentiates anti-tumor effect of resveratrol on pancreatic cancer by down-regulation of VEGF-B signaling pathway

Our previous study showed that resveratrol (RSV) exhibited not only anti-tumor effect, but also had potential tumor promotion effect on pancreatic cancer (Paca) cells through up-regulation of VEGF-B. We determined whether metformin (MET) could potentiate the anti-tumor effect of RSV on PaCa in this study. Combination of RSV (100 μmol/l) and MET (20 mmol/l) significantly inhibited tumor growth and increased apoptosis of human PaCa in comparison with RSV or MET alone treatment in PaCa cell lines (Miapaca-2, Panc-1 and Capan-2). Combination of RSV (60 mg/kg, gavage) and MET (250 mg/kg, i.p.) significantly inhibited tumor growth in PaCa bearing nude mice (subcutaneous injection of 5 × 10⁶ Miapaca-2 cells) in comparison with RSV or MET alone treatment on day 40. Combination treatment significantly decreased VEGF-B expression and inhibited activity of GSK-3β when compared to the RSV alone treatment. Up-regulated expressions of Bax, cleaved caspase-3 and down-regulated expression of Bcl-2 were observed in RSV+ MET group in comparison with RSV group either in vitro or in vivo. Inhibition of VEGF-B by VEGF-B small interfering RNA (siRNA) mimicked the effects of MET on PaCa cells. These results suggested that MET, a potential pharmacological inhibitor of VEGF-B signaling pathway, potentiated the anti-tumor effect of RSV on PaCa, and combination of MET and RSV would be a promising modality for clinical PaCa therapy.

Resveratrol inhibits Interleukin-6 induced invasion of human gastric cancer cells

Previous studies show that migration and invasion are the primary causes of death in patients with gastric carcinoma. Increasing evidences have been shown Interleukin-6 could stimulate cancer cells invasion and be associated with cancer development. However, its role in gastric cancer has never been investigated. As an anticancer drug isolated from Chinese medicine, resveratrol was reported to inhibit cancer cells growth and induce apoptosis, but its roles in gastric cancer have not been well understood. In this study, we found that Interleukin-6 was upregulated in blood of gastric cancer patients by enzyme-linked immunosorbent assay. In gastric cancer cell line model, we found that non-cytotoxic concentration of resveratrol inhibited the Interleukin-6 induced SGC7901 cell invasion and matrix metalloproteinases activation. Our studies showed that IL-6 induced SGC7901 cell invasion depends on the Raf/MAPK pathway activation, resveratrol could inhibit this pathway activation. We further showed that resveratrol inhibits the IL-6 induced metastasis by vein injection of luciferase-labeled cancer cells. In conclusion, these results indicate that Interleukin-6 promotes tumor growth and metastasis in gastric cancer, resveratrol has the potential to prevent the Interleukin-6 induced gastric cancer metastasis by blocking the Raf/MAPK signaling activation.

Resveratrol changes spermatogonial stem cells (SSCs) activity and ameliorates their loss in busulfan-induced infertile mouse

The decline of quantity and quality of sperm are correlated with the increasing age and some anti-cancer compounds such as busulfan. Previous studies have shown that Resveratrol (Res) inhibits tumorigenesis and metastasis of many cancers including mammary tumor, prostate and pancreatic cancers. It acts as anti-age in mouse and human, however, little is known about its protective effect on aged spermatogonial stem cells (SSCs). Here, we investigated the effects of Res in vitro on SSCs using C18-4 cells and in vivo in busulfan-induced azoospermia mice model. The results showed that Res at different concentrations had different effects on C18-4 cells. Treatment with 2 μM of Res promotes cell proliferation and inhibits apoptosis, but stimulates apoptosis with a higher concentration (20 μM) in C18-4 cells. Using busulfan-induced infertility mice model, we demonstrated that Res (30 mg/kg/d and 100 mg/kg/d) clearly ameliorated SSC loss to recover the spermatogenesis. Taken together, our data suggest that Res might be an approach for therapeutic intervention to promote SSC proliferation and cease SSC loss in azoospermia mice model induced by busulfan.

miR-181a-5p suppresses invasion and migration of HTR-8/SVneo cells by directly targeting IGF2BP2

Pre-eclampsia is a pregnancy-related disease that may cause maternal, neonatal and fetal morbidity and mortality and exists in 3–5% of pregnancies worldwide. The discovery of dysregulated microRNAs and their roles in placental development has provided a new avenue for elucidating the mechanism involved in this pregnancy-specific disorder. Here, the roles of human miR-181a-5p, a microRNA that is increased in both the plasma and placenta of severe pre-eclamptic patients, in invasion and migration of trophoblasts were investigated. Ectopic-expression of miR-181a-5p impaired the invasion and migration of HTR-8/SVneo cells, whereas miR-181a-5p inhibition had the opposite effects. IGF2BP2, which harbors a highly conserved miR-181a-5p-binding site within its 3ʹ-UTR, was identified to be directly inhibited by miR-181a-5p. Moreover, siRNAs targeting IGF2BP2 imitated the effects of overexpressed miR-181a-5p on HTR-8/SVneo cell invasion and migration, whereas restoring IGF2BP2 expression by overexpressing a plasmid encoding IGF2BP2 partially reversed the studied inhibitory functions of miR-181a-5p. Thus, we demonstrated here that miR-181a-5p suppresses the invasion and migration of cytotrophoblasts, and its inhibitory effects were at least partially mediated by the suppression of IGF2BP2 expression, thus shedding new light on the roles of miR-181a-5p in the pathogenesis of severe pre-eclampsia.

Resveratrol induces autophagic apoptosis via the lysosomal cathepsin D pathway in human drug-resistant K562/ADM leukemia cells

The aim of the present study was to investigate the crosstalk between resveratrol (Res)-induced autophagy and apoptosis, and the molecular pathway by which autophagy leads to apoptotic death in drug-resistant K562/ADM leukemia cells. The viability of K562/ADM cells was determined using the MTT assay. The formation of autophagic vacuoles was detected using transmission electron microscopy and monodansylcadaverine (MDC) staining. Cell apoptosis was evaluated using flow cytometry. The expression of apoptosis- or autophagy-associated proteins was measured using western blotting. The results indicated that treatment with Res inhibited cell viability in a concentration-dependent manner. Furthermore, the numbers of MDC-positive fluorescent points, autophagic vacuoles and autolysosome-engulfed cytoplasmic materials were markedly increased in Res-treated K562/ADM cells compared with untreated cells, as determined using fluorescence microscopy and transmission electron microscopy. Res-induced apoptosis was associated with increased cleaved caspase-3 and B-cell lymphoma 2 associated X protein, and decreased B-cell lymphoma 2 (Bcl-2) protein expression levels when compared with the control (P<0.05). However, the proportion of apoptotic cells decreased from 69.6 to 41.0% (40 µmol/l Res) and from 77.3 to 58.8% (80 µmol/l Res) following pre-treatment with the autophagy inhibitor 3-methyladenine (P<0.01). The protein expression levels of microtubule-associated protein 1A/1B-light chain 3 and beclin 1, two markers of autophagy, were upregulated in Res-treated cells compared with the control (P<0.05). In addition, lysosomal cathepsin D (Cath D) release increased during Res-induced autophagy and apoptosis (P<0.05). The present results demonstrated that Res-induced apoptosis of K562/ADM cells was autophagy-dependent and the released Cath D may trigger caspase-dependent cell death through the Bcl-2 family of proteins. Furthermore, the present data indicate that to enhancement of the autophagy-cathepsin-apoptosis pathway may be an effective approach for overcoming anticancer drug resistance.

Effects of Resveratrol against Lung Cancer: In Vitro and In Vivo Studies

Uncontrolled cell growth and resistance to apoptosis characterize cancer cells. These two main features are initiated in cancer cells through mutations in key signaling molecules, which regulate pathways that are directly involved in controlling cell proliferation and apoptosis. Resveratrol (RSV), a naturally occurring plant polyphenol, has been shown to have biological effects counteracting different diseases. It has been found to provide cardio-protective, neuro-protective, immuno-modulatory, and anti-cancer health benefits. RSV has been found to inhibit cancer cell proliferation, induce cell cycle arrest and apoptosis, and these anticancer effects may be due to its ability to modulate signaling molecules involved in these processes. The present review summarizes the existing in vitro and in vivo studies on resveratrol and its anti-lung cancer properties.

Resveratrol induces mitochondria-mediated, caspase-independent apoptosis in murine prostate cancer cells

Found in the skins of red fruits, including grapes, resveratrol (RES) is a polyphenolic compound with cancer chemopreventive activity. Because of this activity, it has gained interest for scientific investigations. RES inhibits tumor growth and progression by targeting mitochondria-dependent or -independent pathways. However, further investigations are needed to explore the underlying mechanisms.

The present study is focused on examining the role of RES-induced, mitochondria-mediated, caspase-independent apoptosis of prostate cancer cells, namely transgenic adenocarcinoma of mouse prostate (TRAMP) cells. These cells were exposed to RES for various times, and cell killing, cell morphology, mitochondrial membrane potential (Δψm), expression of Bax and Bcl2 proteins, the role of caspase-3, and DNA fragmentation were analyzed.

TRAMP cells exposed to RES showed decreased cell viability, altered cell morphology, and disrupted Δψm, which led to aberrant expression of Bax and Bcl2 proteins. Furthermore, since the caspase-3 inhibitor, z-VAD-fmk (benzyloxycarbonyl-valine-alanine-aspartic acid-fluoromethyl ketone), had no appreciable impact on RES-induced cell killing, the killing was evidently caspase-independent. In addition, RES treatment of TRAMP-C1, TRAMP-C2, and TRAMP-C3 cells caused an appreciable breakage of genomic DNA into low-molecular-weight fragments.

These findings show that, in inhibition of proliferation of TRAMP cells, RES induces mitochondria-mediated, caspase-independent apoptosis. Therefore, RES may be utilized as a therapeutic agent to control the proliferation and growth of cancer cells.

trans-4,4'-Dihydroxystilbene (DHS) inhibits human neuroblastoma tumor growth and induces mitochondrial and lysosomal damages in neuroblastoma cell lines

In view of the inadequacy of neuroblastoma treatment, five hydroxystilbenes and resveratrol (Resv) were screened for their cytotoxic property against human neuroblastoma cell lines. The mechanism of cytotoxic action of the most potent compound, trans-4,4'-dihydroxystilbene (DHS) was investigated in vitro using human neuroblastoma cell lines. DHS was also tested in a mouse xenograft model of human neuroblastoma tumor. The MTT, sub-G1, annexin V and clonogenic assays as well as microscopy established higher cytotoxicity of DHS than Resv to the IMR32 cell line. DHS (20 μM) induced mitochondrial membrane permeabilization (MMP) in the cells, as revealed from JC-1 staining, cytochrome c and ApaF1 release and caspases-9/3 activation. DHS also induced lysosomal membrane permeabilization (LMP) to release cathepsins B, L and D, and the cathepsins inhibitors partially reduced MMP/caspase-3 activation. The ROS, produced by DHS activated the p38 and JNK MAPKs to augment the BAX activity and BID-cleavage, and induce LMP and MMP in the cells. DHS (100 mg/kg) also inhibited human neuroblastoma tumor growth in SCID mice by 51%. Hence, DHS may be a potential chemotherapeutic option against neuroblastoma. The involvement of an independent LMP as well as a partially LMP-dependent MMP by DHS is attractive as it provides options to target both mitochondria and lysosome.

Resveratrol protects podocytes against apoptosis via stimulation of autophagy in a mouse model of diabetic nephropathy

Podocyte apoptosis coincides with albuminuria onset and precedes podocytopenia in diabetic nephropathy. However, there is a lack of effective therapeutic drugs to protect podocytes from apoptosis. Here, we demonstrated that resveratrol relieved a series of indicators of diabetic nephropathy and attenuated apoptosis of podocytes in db/db diabetic model mice. In addition, resveratrol induced autophagy in both db/db mice and human podocytes. Furthermore, inhibition of autophagy by 3-methyladenine (3-MA) and autophagy gene 5 (Atg5) short hairpin RNA (shRNA) reversed the protective effects of resveratrol on podocytes. Finally, we found that resveratrol might regulate autophagy and apoptosis in db/db mice and podocytes through the suppression of microRNA-383-5p (miR-383-5p). Together, our results indicate that resveratrol effectively attenuates high glucose-induced apoptosis via the activation of autophagy in db/db mice and podocytes, which involves miR-383-5p. Thus, this study reveals a new possible strategy to treat diabetic nephropathy.

Natural Compounds As Modulators of Non-apoptotic Cell Death in Cancer Cells

Cell death is an innate capability of cells to be removed from microenvironment, if and when they are damaged by multiple stresses. Cell death is often regulated by multiple molecular pathways and mechanism, including apoptosis, autophagy, and necroptosis. The molecular network underlying these processes is often intertwined and one pathway can dynamically shift to another one acquiring certain protein components, in particular upon treatment with various drugs. The strategy to treat human cancer ultimately relies on the ability of anticancer therapeutics to induce tumor-specific cell death, while leaving normal adjacent cells undamaged. However, tumor cells often develop the resistance to the drug-induced cell death, thus representing a great challenge for the anticancer approaches. Numerous compounds originated from the natural sources and biopharmaceutical industries are applied today in clinics showing advantageous results. However, some exhibit serious toxic side effects. Thus, novel effective therapeutic approaches in treating cancers are continued to be developed. Natural compounds with anticancer activity have gained a great interest among researchers and clinicians alike since they have shown more favorable safety and efficacy then the synthetic marketed drugs. Numerous studies in vitro and in vivo have found that several natural compounds display promising anticancer potentials. This review underlines certain information regarding the role of natural compounds from plants, microorganisms and sea life forms, which are able to induce non-apoptotic cell death in tumor cells, namely autophagy and necroptosis.

Caveolin-1 in the regulation of cell metabolism: a cancer perspective

Caveolin-1 (CAV1) is an oncogenic membrane protein associated with endocytosis, extracellular matrix organisation, cholesterol distribution, cell migration and signaling. Recent studies reveal that CAV1 is involved in metabolic alterations – a critical strategy adopted by cancer cells to their survival advantage. Consequently, research findings suggest that CAV1, which is altered in several cancer types, influences tumour development or progression by controlling metabolism. Understanding the molecular interplay between CAV1 and metabolism could help uncover druggable metabolic targets or pathways of clinical relevance in cancer therapy. Here we review from a cancer perspective, the findings that CAV1 modulates cell metabolism with a focus on glycolysis, mitochondrial bioenergetics, glutaminolysis, fatty acid metabolism, and autophagy.

Diosmetin inhibits cell proliferation and induces apoptosis by regulating autophagy via the mammalian target of rapamycin pathway in hepatocellular carcinoma HepG2 cells

Hepatocellular carcinoma (HCC), which is a type of malignant tumor, is the fifth most common cancer in men and ninth in women worldwide. The aim of the present study was to investigate the antitumor effect of diosmetin (DIOS) in hepatocellular carcinoma HepG2 cells. The proliferation, apoptosis and autophagy rates of HepG2 cells were measured following treatment with DIOS. The effects of DIOS treatment on HepG2 cell proliferation and apoptosis rates were analyzed using MTT assays and Annexin V staining, respectively. The effect of DIOS treatment on autophagy levels was assessed using transmission electron microscopy, green fluorescent protein (GFP)-microtubule-associated protein 1 light chain (LC3) transfection and LysoTracker Red staining. Furthermore, bafilomycin A1 (BA1), an autophagy inhibitor, was used to assess the association between DIOS and cell autophagy, proliferation and apoptosis. In addition, the expression of autophagy-related proteins [mammalian target of rapamycin (mTOR), phosphatidylinositol 3-kinase, P70S6K, phosphoinositide-dependent kinase-1, extracellular signal-regulated kinase, 5′-AMP-activated protein kinase and Akt] and apoptosis-related proteins [B-cell lymphoma (Bcl)-2-associated X protein, Bak, p53, Bcl-2 and caspase-3] were analyzed by western blotting. The results revealed that DIOS significantly inhibited proliferation (P<0.01) and induced apoptosis (P<0.001) in HepG2 cells. It was also demonstrated that DIOS triggered autophagy by regulating the mTOR pathway in HepG2 cells. Notably, following treatment of HepG2 cells with the autophagy inhibitor, BA1, the expression of apoptosis-related proteins, including Bax, Bak and p53, were significantly decreased (P<0.05), and cell viability was recovered to a certain extent. In conclusion, DIOS inhibits cell proliferation and induces apoptosis in HepG2 cells via regulation of the mTOR pathway. Thus, the results of the current study indicate that DIOS may present a potential therapeutic agent for HCC treatment.

18α-Glycyrrhetinic acid lethality for neuroblastoma cells via de-regulating the Beclin-1/Bcl-2 complex and inducing apoptosis

18α-Glycyrrhetinic acid (18-GA) is a known gap-junction inhibitor with demonstrated anticancer effects. However, the different modes of cell cytotoxicity for 18-GA remain to be characterized. In this study, 18-GA reduced the expression of cell-cell interaction proteins (N- and VE-cadherin), and led to a dose-dependent increase in cytotoxicity of the neuroblastoma cells tested, but was less toxic toward actively dividing human embryonic kidney cells. We found that 18-GA could induce both autophagy and apoptosis. 18-GA mediated autophagy was due to accumulation of Atg5, Atg7 and LC3II and degradation of p62. Individual siRNAs against Atg5 and Atg7 prevented autophagy and resulted in a further loss of viability with 18-GA. In addition, combination of 18-GA with autophagy inhibitor chloroquine produced a more significant cell death. This implied a pro-survival function for autophagy induction with 18-GA. 18-GA also led to the destabilization of Bcl-2/Beclin-1 interaction and cleavage of Beclin-1, a protein known to play role in apoptosis and autophagy induction. Treatment of cells by a pan-caspase inhibitor or a caspase-3 siRNA prevented a large portion of 18-GA mediated cytotoxicity, demonstrating that caspase-dependent apoptosis induction was responsible for most of the observed cytotoxicity. In terms of signaling, 18-GA led to reduced phosphorylation of all three classes of MAP kinases. Taken together, 18-GA or its pathways may lead to more effective, targeted therapeutics against neuroblastoma.

Classical and atypical resistance of cancer cells as a target for resveratrol

The phenomenon of cancer cell resistance to chemotherapeutics is the main cause of insensitivity to anticancer therapy. Thus, the current challenge remains searching for substances sensitising the activity of cytostatic drugs. In this respect, resveratrol is a very promising therapeutic agent. It has pleiotropic effect on cancer cells, which can play a key role in numerous resistance mechanisms, both classical and atypical. The purpose of the present study was to assess the effect of resveratrol on the inhibition of human pancreatic cancer cell proliferation and on the level of cytostatic resistance-associated proteins. The study was performed on human pancreatic cancer cell lines EPP85-181P (control), EPP85-181RDB (daunorubicin resistance) and EPP85-181PRNOV (mitoxantrone resistance). The effect of resveratrol on the viability and proliferation of the studied cell lines was evaluated by SRB assay, whereas cell cycle arrest and cytostatic accumulation by FACS. Western blot analysis was used to determine the level of P-glycoprotein, topoisomerase II α and β and immunofluorescence technique to visualise the proteins in the cells. Resveratrol inhibited proliferation of all studied cell lines. Phase-specific cell cycle arrest depended on the type of cancer cells. Resveratrol decreased the level and activity of P-gp in EPP85-181RDB cells. In EPP85-181PRNOV cells, expression of both TopoII isoforms increased in a statistically significant manner. The results of in vitro studies support the possibility of potential use of resveratrol in breaking cancer cell resistance to chemotherapeutic drugs.

Autophagy and apoptosis in liver injury

Apoptosis is a primary characteristic in the pathogenesis of liver disease. Hepatic apoptosis is regulated by autophagic activity. However, mechanisms mediating their interaction remain to be determined. Basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy also is an adaptive response under stressful conditions. Autophagy can control cell fate through different cross-talk signals. A complex interplay between hepatic autophagy and apoptosis determines the degree of hepatic apoptosis and the progression of liver disease as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances on roles of autophagy that plays in pathophysiology of liver. The autophagic pathway can be a novel therapeutic target for liver disease.

N-n-butyl haloperidol iodide protects cardiomyocytes against hypoxia/reoxygenation injury by inhibiting autophagy

N-n-butyl haloperidol iodide (F2), a novel compound derived from haloperidol, protects against the damaging effects of ischemia/reperfusion (I/R) injury in vitro and in vivo. In this study, we hypothesized the myocardial protection of F2 on cardiomyocyte hypoxia/reoxygenation (H/R) injury is mediated by inhibiting autophagy in H9c2 cells. The degree of autophagy by treatment with F2 exposed to H/R in H9c2 cell was characterized by monodansylcadaverine, transmission electron microscopy, and expression of autophagy marker protein LC3. Our results indicated that treatment with F2 inhibited autophagy in H9c2 cells exposed to H/R. 3-methyladenine, an inhibitor of autophagy, suppressed H/R-induced autophagy, and decreased apoptosis, whereas rapamycin, a classical autophagy sensitizer, increased autophagy and apoptosis. Mechanistically, macrophage migration inhibitory factor (MIF) was inhibited by F2 treatment after H/R. Accordingly, small interfering RNA (siRNA)-mediated MIF knockdown decreased H/R-induced autophagy. In summary, F2 protects cardiomyocytes during H/R injury through suppressing autophagy activation. Our results provide a new mechanistic insight into a functional role of F2 against H/R-induced cardiomyocyte injury and death.

The critical molecular interconnections in regulating apoptosis and autophagy

Apoptosis and autophagy are both highly regulated biological processes that have important roles in development, differentiation, homeostasis, and disease. These processes may take place independently, with autophagy being cytoprotective for preventing cells from apoptosis and apoptosis blocking autophagy. But in most circumstances, both may be induced sequentially with autophagy preceding apoptosis. The simultaneous activation of both processes has been observed not only in experimental settings but also in pathophysiological conditions. In fact, these two pathways are tightly connected with each other by substantial interplays between them, enabling the coordinated regulation of cell fates by these two pathways. They share some common upstream signaling components, and some components of one pathway may play important roles in the other, and vice versa. Such proteins represent the critical interconnections of the two pathways, which seem to determine the cell for survival or death. Here several critical molecular interconnections between apoptosis and autophagy pathways are reviewed, with their action mechanisms being highlighted.