AMPK activation-dependent autophagy compromises oleanolic acid-induced cytotoxicity in human bladder cancer cells

Autophagy flux in bladder cancer: Cell death crosstalk, drug and nanotherapeutics

Autophagy, a self-digestion mechanism, has emerged as a promising target in the realm of cancer therapy, particularly in bladder cancer (BCa), a urological malignancy characterized by dysregulated biological processes contributing to its progression. This highly conserved catabolic mechanism exhibits aberrant activation in pathological events, prominently featured in human cancers. The nuanced role of autophagy in cancer has been unveiled as a double-edged sword, capable of functioning as both a pro-survival and pro-death mechanism in a context-dependent manner. In BCa, dysregulation of autophagy intertwines with cell death mechanisms, wherein pro-survival autophagy impedes apoptosis and ferroptosis, while pro-death autophagy diminishes tumor cell survival. The impact of autophagy on BCa progression is multifaceted, influencing metastasis rates and engaging with the epithelial-mesenchymal transition (EMT) mechanism. Pharmacological modulation of autophagy emerges as a viable strategy to impede BCa progression and augment cell death. Notably, the introduction of nanoparticles for targeted autophagy regulation holds promise as an innovative approach in BCa suppression. This review underscores the intricate interplay of autophagy with cell death pathways and its therapeutic implications in the nuanced landscape of bladder cancer.

WTAP regulates autophagy in colon cancer cells by inhibiting FLNA through N6-methyladenosine

Our study investigated the role of WTAP in colon cancer. We employed experiments including m6A dot blot hybridization, methylated RNA immunoprecipitation, dual-luciferase, and RNA immunoprecipitation to investigate the regulatory mechanism of WTAP. Western blot was performed to analyze the expression of WTAP, FLNA and autophagy-related proteins in cells. Our results confirmed the up-regulation of WTAP in colon cancer and its promoting effect on proliferation and inhibiting effect on apoptosis. FLNA was the downstream gene of WTAP and WTAP-regulated m6A modification led to post-transcriptional repression of FLNA. The rescue experiments showed that WTAP/FLNA could inhibit autophagy. WTAP-mediated m6A modification was confirmed to be crucial in colon cancer development, providing new insights into colon cancer therapy.

Targeted inhibition of mTOR by BML-275 induces mitochondrial-mediated apoptosis and autophagy in prostate cancer

Prostate cancer (PCa) is the most frequently diagnosed cancer among men and the second leading cause of death in Western countries. Clinically, screening drugs and develop developing new therapeutics to treat PCa is of great significance. In this study, BML-275 was demonstrated to exert potent antitumor effects in PCa by antagonizing mTOR activity. In cultured PCa cells, BML-275 treatment reduced the expression levels of c-Myc and survivin, promoted the activation of p53, and thereby induced p21/cyclin D1/CDK4/6-dependent cell cycle G1/S arrest. As a result, BML-275 inhibited cellular proliferation and induced mitochondrial-mediated apoptosis. In addition, BML-275 treatment triggered autophagy. Interestingly, EACC-mediated suppression of autophagy did not affect BML-275-induced proliferation and apoptosis. Nude mouse tumorigenic experiments also confirmed that BML-275 inhibited PCa growth, induced PCa cell apoptosis and autophagy. Mechanistically, the activities of PI3K/AKT and AMPK pathways were downregulated by BML-275 treatment in vitro and in vivo. Importantly, mTOR, a common downstream negative protein of PI3K/AKT and AMPK signaling, was induced to inactivate, which may be associated with the induction of apoptosis and autophagy. The pharmacological activation of mTOR by MHY1485 abolished the induction of apoptosis and autophagy of BML-275. Molecular docking results showed that BML-275 can bind to the FKRP12-rapamycin binding site on mTOR protein, and thereby may have the same inhibitory activity on mTOR as rapamycin. Thus, these findings indicated that BML-275 induces mitochondrial-mediated apoptosis and autophagy in PCa by targeting mTOR inhibition. BML-275 may be a potential candidate for the treatment of PCa.

Proteomes from AMPK-inhibited peripheral blood mononuclear cells suppress the progression of breast cancer and bone metastasis

Background: During a developmental process, embryos employ varying tactics to remove unwanted cells. Using a procedure analogous to some of the embryonic cells, we generated a tumor-eliminating conditioned medium (CM) from AMPK-inhibited lymphocytes and monocytes in peripheral blood mononuclear cells (PBMCs). Methods: AMPK signaling was inhibited by the application of a pharmacological agent, Dorsomorphin, and the therapeutic effects of their conditioned medium (CM) were evaluated using in vitro cell cultures, ex vivo breast cancer tissues, and a mouse model of mammary tumors and tumor-induced osteolysis. The regulatory mechanism was evaluated using mass spectrometry-based proteomics, Western blotting, immunoprecipitation, gene overexpression, and RNA interference. Results: While AMPK signaling acted mostly anti-tumorigenic, we paradoxically inhibited it to build induced tumor-suppressing cells and their tumor-eliminating CM. In a mouse model of breast cancer, the application of AMPK-inhibited lymphocyte-derived CM reduced mammary tumors additively to a chemotherapeutic agent, Taxol. It also prevented bone loss in the tumor-bearing tibia. Furthermore, the application of CM from the patient-derived peripheral blood diminished ex vivo breast cancer tissues isolated from the same patients. Notably, proteins enriched in CM included Moesin (MSN), Enolase 1 (ENO1), and polyA-binding protein 1 (PABPC1), which are considered tumorigenic in many types of cancer. The tumor-suppressing actions of MSN and ENO1 were at least in part mediated by Metadherin (Mtdh), which is known to promote metastatic seeding. Conclusion: We demonstrated that PBMCs can be used to generate tumor-suppressive proteomes, and extracellular tumor-suppressing proteins such as MSN, ENO1, and PABPC1 are converted from tumor-promoting factors inside cancer cells. The results support the possibility of developing autologous blood-based therapy, in which tumor-suppressing proteins are enriched in engineered PBMC-derived CM by the inhibition of AMPK signaling.

Anticancer activity of oleanolic acid and its derivatives modified at A-ring and C-28 position

Oleanolic acid (OA) is a five-ring triterpenoid compound, which is widely present in plants. Due to a wide range of pharmacological activities, oleanolic acid has attracted more and more attention. However, oleanolic acid is insoluble in water and has low bioavailability, which limits its clinical application. In this review, we focus on summarizing the anti-cancer activity and mechanism of the A ring or C-28 carboxyl modified derivatives of OA since 2015, to determine the strength of its anti-cancer effectiveness and evaluate whether it could be used as a clinical anti-cancer drug.

Systematic Review of Potential Anticancerous Activities of Erythrina senegalensis DC (Fabaceae)

The objective of this study was to carry out a systematic review of the substances isolated from the African medicinal plant Erythrina senegalensis, focusing on compounds harboring activities against cancer models detailed in depth herein at both in vitro and in vivo preclinical levels. The review was conducted through Pubmed and Google Scholar. Nineteen out of the forty-two secondary metabolites isolated to date from E. senegalensis displayed interesting in vitro and/or in vivo antitumor activities. They belonged to alkaloid (Erysodine), triterpenes (Erythrodiol, maniladiol, oleanolic acid), prenylated isoflavonoids (senegalensin, erysenegalensein E, erysenegalensein M, alpinumisoflavone, derrone, warangalone), flavonoids (erythrisenegalone, senegalensein, lupinifolin, carpachromene) and pterocarpans (erybraedine A, erybraedine C, phaseollin). Among the isoflavonoids called "erysenegalensein", only erysenealenseins E and M have been tested for their anticancerous properties and turned out to be cytotoxic. Although the stem bark is the most frequently used part of the plant, all pterocarpans were isolated from roots and all alkaloids from seeds. The mechanisms of action of its metabolites include apoptosis, pyroptosis, autophagy and mitophagy via the modulation of cytoplasmic proteins, miRNA and enzymes involved in critical pathways deregulated in cancer. Alpinumisoflavone and oleanolic acid were studied in a broad spectrum of cancer models both in vitro and in preclinical models in vivo with promising results. Other metabolites, including carpachromen, phaseollin, erybraedin A, erysenegalensein M and maniladiol need to be further investigated, as they display potent in vitro effects.

Anticancer activity of oleanolic acid and its derivatives: Recent advances in evidence, target profiling and mechanisms of action

Oleanolic acid (OA, 3 β - hydroxyoleanolic acid-12-en-28-oic acid) is a pentacyclic triterpenoid present in many plants. As a new framework for development of semi synthetic triterpenoids, OA is of great significance in the discovery of anticancer drugs. Some of these derivatives, such as CDDO (2-cyano-3,12-dioxooleana-1, 9 (11)-dien-28-oic acid) have been verified in clinical trials, while other derivatives studied previously, such as SZC014, SZC015 and SZC017 (OA derivatives respectively), are also candidate drugs for cancer treatment. This paper reviews the preclinical studies, literature evidence, target analysis and anticancer mechanism of OA and its derivatives. The mechanism of action of its derivatives mainly includes anti-cancer cell proliferation, inducing tumor cell apoptosis, inducing autophagy, regulating cell cycle regulatory proteins, inhibiting vascular endothelial growth, anti angiogenesis, inhibiting tumor cell migration and invasion. In recent years, the molecular mechanism of OA and its derivatives has been elucidated. These effects seem to be mediated by the alterations in a variety of signaling pathways induced by OA and its derivatives. In conclusion, OA and its derivatives are considered as important candidate drugs for the treatment of cancer, indicating that OA and its derivatives have the potential to be used as anticancer drugs in practice.

Terpenoids' anti-cancer effects: focus on autophagy

Terpenoids are the largest class of natural products, most of which are derived from plants. Amongst their numerous biological properties, their anti-tumor effects are of interest for they are extremely diverse which include anti-proliferative, apoptotic, anti-angiogenic, and anti-metastatic activities. Recently, several in vitro and in vivo studies have been dedicated to understanding the 'terpenoid induced autophagy' phenomenon in cancer cells. Light has already been shed on the intricacy of apoptosis and autophagy relationship. This latter crosstalk is driven by the delicate balance between activating or silencing of certain proteins whereby the outcome is expressed via interrelated signaling pathways. In this review, we focus on nine of the most studied terpenoids and on their cell death and autophagic activity. These terpenoids are grouped in three classes: sesquiterpenoid (artemisinin, parthenolide), diterpenoids (oridonin, triptolide), and triterpenoids (alisol, betulinic acid, oleanolic acid, platycodin D, and ursolic acid). We have selected these nine terpenoids among others as they belong to the different major classes of terpenoids and our extensive search of the literature indicated that they were the most studied in terms of autophagy in cancer. These terpenoids alone demonstrate the complexity by which these secondary metabolites induce autophagy via complex signaling pathways such as MAPK/ERK/JNK, PI3K/AKT/mTOR, AMPK, NF-kB, and reactive oxygen species. Moreover, induction of autophagy can be either destructive or protective in tumor cells. Nevertheless, should this phenomenon be well understood, we ought to be able to exploit it to create novel therapies and design more effective regimens in the management and treatment of cancer.

Bioactivity of fractions and constituents of Piper capense fruits towards a broad panel of cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Piper capense is a medicinal spice whose fruits are traditionally used as aqueous decoction to heal several ailments such as trypanosomiasis, helminthic infections, and cancer.

AIM OF THE STUDY

(1) To perform phytochemical investigation of the methanol extract of Piper capense; (2) to evaluate the cytotoxicity of botanicals (PCF, fractions PCFa-e), isolated phytochemicals on a broad panel of animal and human cancer cell lines; (3) to evaluate the induction of apoptosis of the most active samples.

MATERIAL AND METHODS

Resazurin reduction assay (RRA) was used to determine the cytotoxicity of the studied samples. Cell cycle distribution (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; H₂DCFH-DA) were measured by flow cytometry. Column chromatography (CC) was used for the purification of PCF, whilst nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric (MS) analyses were applied for structural elucidation.

RESULTS

The phytochemical investigation of PCF led to the isolation of 11 compounds: licarin B (1), licarin A (2), 7-(1,3-benzodioxol-5-yl)-7,8-dihydro-8-methyl-5-(2-propenyl)-furo[3,2-e]-1,3-benzodioxole (3), nitidine isocyanate (4), 5-hydroxy-7,4'-dimethoxyflavone (5), cardamomin (6), sitosterol (7) and stigmasterol (8), β-sitosterol 3-O-β-_D-glucopyranoside (9), oleanolic acid (10) and lupeol (11). Fraction PCFb, compound 2 and doxorubicin (as positive control drug) revealed cytotoxic effects towards the 18 tested cancer cell lines. The IC₅₀ values ranged from 6.1 μg/mL (against CCRF-CEM cells) to 44.2 μg/mL (against BRAF-V600E homozygous mutant melanoma cells) for PSCb; from 4.3 μM (against CCRF-CEM cells) to 21.8 μM (against HCT116 p53^-/-) for compound 2 and from 0.02 μM (against CCRF-CEM cells) to 123.0 μM (against CEM/ADR5000 cells) for doxorubicin. PCFb and compound 2 induced apoptosis in CCRF-CEM cells mediated by activation of caspase 3/7, 8 and 9, MMP alteration and increased ROS production.

CONCLUSION

Piper capense is a source of potent cytotoxic botanicals and phytochemicals that could help to fight various types of cancer including multidrug resistance phenotypes. PCFb and compound 2 should further be explored to develop new drugs to fight malignancies.

The role of autophagy in metal-induced urogenital carcinogenesis

Environmental and/or occupational exposure to metals such as Arsenic (As), Cadmium (Cd), and Chromium (Cr) have been shown to induce carcinogenesis in various organs, including the urogenital system. However, the mechanisms responsible for metal-induced carcinogenesis remain elusive. We and others have shown that metals are potent inducers of autophagy, which has been suggested to be an adaptive stress response to allow metal-exposed cells to survive in hostile environments. Albeit few, recent experimental studies have shown that As and Cd promote tumorigenesis via autophagy and that inhibition of autophagic signaling suppressed metal-induced carcinogenesis. In light of the newly emerging role of autophagic involvement in metal-induced carcinogenesis, the present review focuses explicitly on the mechanistic role of autophagy and potential signaling pathways involved in As-, Cd-, and Cr-induced urogenital carcinogenesis.

Combined Extracts of Epimedii Folium and Ligustri Lucidi Fructus with Budesonide Attenuate Airway Remodeling in the Asthmatic Rats by Regulating Apoptosis and Autophagy

This study aimed to investigate the effects of the coadministration of budesonide (Bud) and the extracts of Epimedii Folium and Ligustri Lucidi Fructus (EEL) on regulating apoptosis and autophagy in asthmatic rats. Forty Sprague-Dawley rats were divided randomly into five groups (8 rats in each group): normal control (control), asthma model (asthma), Bud (1 mg Bud suspension in 50 ml sterile physiological saline for 30 min), EEL (100 mg/kg EEL), and group of coadministration of Bud and EEL (Bud&EEL, 100 mg/kg EEL plus Bud by nebulized inhalation for 30 min). Rats were sensitized and challenged with ovalbumin for 7 weeks and treated with corresponding drug for 4 weeks. We anesthetized all rats with 25% ethyl carbamate (4 ml/kg) and took lung tissues and BALF after final ovalbumin challenge to observe the lung histopathology and morphometry; apoptosis in BALF and lung tissue; protein expressions of Ki-67, α-SMA, cleaved Caspase-3, p-mTOR, and LC3; and protein and mRNA expressions of Bax, Bcl-2, Caspase-3, P53, mTOR, and Beclin-1. Results showed that Bud&EEL could alleviate airway remodeling, inhibit cell proliferation and autophagy in lung tissue, and promote apoptosis in BALF and lung tissue in ovalbumin-induced asthma rats through downregulating the protein expressions of α-SMA and Ki-67, the protein ratio of LC3-II/LC3-I and Bcl-2/Bax, and the protein and mRNA expressions of Bcl-2 and Beclin-1, while upregulating the protein expressions of cleaved Caspase-3 and p-mTOR, and the protein and mRNA expressions of Bax, Caspase-3, P53, and mTOR. Bud&EEL had better effects than single-use Bud on improving airway remodeling, promoting apoptosis, and regulating the expressions of autophagy- and apoptosis-related proteins. This study suggested that the effects of coadministration of EEL and Bud on regulating apoptosis and autophagy were better than those of single-use Bud treatment, and that might be the mechanism of attenuating airway remodeling, providing an alternative therapy for asthma.

Targeting autophagy-related protein kinases for potential therapeutic purpose

Autophagy, defined as a scavenging process of protein aggregates and damaged organelles mediated by lysosomes, plays a significant role in the quality control of macromolecules and organelles. Since protein kinases are integral to the autophagy process, it is critically important to understand the role of kinases in autophagic regulation. At present, intervention of autophagic processes by small-molecule modulators targeting specific kinases has becoming a reasonable and prevalent strategy for treating several varieties of human disease, especially cancer. In this review, we describe the role of some autophagy-related kinase targets and kinase-mediated phosphorylation mechanisms in autophagy regulation. We also summarize the small-molecule kinase inhibitors/activators of these targets, highlighting the opportunities of these new therapeutic agents.

Identification and validation of an individualized autophagy-clinical prognostic index in bladder cancer patients

Purpose: Autophagy is a major catabolic system by which eukaryotic cells undergo self-degradation of damaged, defective, or unwanted intracellular components. An abnormal autophagic level is implicated in the pathogenesis of multiple diseases, including cancers. The aim of this study is to explore the prognostic value of autophagy in bladder cancer (BC), which is a major cause of cancer-related death globally.

Patients and methods: First, 27 differentially expressed autophagy-related genes (ARGs) were identified in BC patients based on The Cancer Genome Atlas (TCGA) database. Functional enrichment analyses hinted that autophagy may act in a tumor-suppressive role in the initiation of BC. Then, the Cox proportional hazard regression model were employed to identify three key prognostic ARGs (JUN, MYC, and ITGA3), which were related with overall survival (OS) significantly in BC. The three genes represented important clinical significance and prognostic value in BC. Then a prognostic index (PI) was constructed.

Results: The PI was constructed based on the three genes, and significantly stratified BC patients into high- and low-risk groups in terms of OS (HR=1.610, 95% CI=1.200–2.160, P=0.002). PI remained as an independent prognostic factor in multivariate analyses (HR=2.355, 95% CI=1.483–3.739, P<0.001). When integrated with clinical characteristics of age and stage, an autophagy-clinical prognostic index (ACPI) was finally validated, which had improved performance in predicting OS of BC patients (HR=2.669, 95% CI=1.986–3.587, P<0.001). The ACPI was confirmed in datasets of GSE13507 (HR=7.389, 95% CI=3.645–14.980, P<0.001) and GSE31684 (HR=1.665, 95% CI=0.872–3.179, P=0.122).

Conclusion: This study provides a potential prognostic signature for predicting prognosis of BC patients and molecular insights of autophagy in BC.

Molecular evidence for better efficacy of hypocrellin A and oleanolic acid combination in suppression of HCC growth

Hepatocellular carcinoma (HCC) is one of the most frequently occurring cancer worldwide and the fifth most common malignancy. The Hippo pathway has been found to play a critical role in cancer development. YAP, a transcriptional coactivator, is the major downstream effector of the Hippo signaling pathway. Hypocrellin A (HA), a natural perylenequinone light-sensitive compound, is usually used for the therapy of eukoplakia of the vulva and keloids in China. Oleanolic acid (OA), a pentacyclic triterpene compound, is prevalent in the treatment of human liver diseases such as viral hepatitis. In this study, we aimed to explore the mechanism by which HA modulates the Hippo/YAP signaling pathway in HCC cells and the anticancer effect of HA combined with OA. Treatment with HA resulted in a decrease in cell viability and migration in HCC cells. Furthermore, we found that HA decreased the YAP and TEAD protein levels of the Hippo pathway. Next we demonstrated that HA could potentiate OA's effect on HCC cells. Our results indicated that HA could inhibit the growth of HCC cells in darkness through Hippo-YAP signaling and HA combined with OA had a better effect than HA or OA alone.Thus, our results provide an alternative combinational inhibitor to combat hepatocellular carcinoma diseases.

Programmed cell death 4 overexpression enhances sensitivity to cisplatin via the JNK/c-Jun signaling pathway in bladder cancer

The aim of the present study was to evaluate the effects of programmed cell death 4 (PDCD4) on cell proliferation and apoptosis, and to elucidate the potential role of the Jun N-terminal kinase (JNK)/c-Jun pathway in human bladder cancer (BCa) cells. Mixed BCa cells were transfected with plasmids containing PDCD4 (PDCD4-pcDNA3). The sensitivity to cisplatin was analyzed using cell viability, invasion/migration, apoptosis, flow cytometry, wound healing and Transwell assays at different transfection times. Furthermore, epithelial-to-mesenchymal transition (EMT) markers were detected by immunofluorescence staining, and the protein expression of c-Jun, and phosphorylated Jun N-terminal kinase (p-JNK) and c-Jun (p-c-Jun, Ser-73) were also tested using western blotting. It was observed that BCa cell proliferation and invasion and tumor growth were significantly inhibited, whereas apoptosis was enhanced in PDCD4-transfected cells treated with cisplatin compared with controls. Moreover, the western blotting and immunofluorescence results demonstrated that PDCD4 upregulated the expression of epithelial cell markers, but downregulated the expression of mesenchymal cell markers. Furthermore, overexpression of PDCD4 reduced the protein levels of p-JNK and p-c-Jun. Taken together, the findings of the present study indicate that PDCD4 enhances the sensitivity of BCa cells to cisplatin, partially via regulation of the JNK/c-Jun pathway, and reverses EMT. In conclusion, the results of the present study suggested that PDCD4, a nuclear/cytoplasmic shuttling protein with multiple functions, plays an important role in the development and progression of human BCa.

Rapamycin protects against paraquat-induced pulmonary epithelial-mesenchymal transition via the Wnt/β-catenin signaling pathway

Paraquat (PQ) is a herbicide that is widely used in developing countries, and pulmonary fibrosisis one of the most typical features of PQ poisoning. The molecular mechanism underlying PQ toxicity is largely unknown, which makes it difficult to treat. In the present study, western blot analysis, reverse transcription-quantitative polymerase chain reaction and fluorescent immunostaining were used to analyze the effects of rapamycin on PQ-induced epithelial-mesenchymal transition (EMT) in A549 and MRC-5 cells. It was revealed that rapamycin significantly downregulated the mesenchymal cell marker, α-smooth muscle actin, and significantly upregulated the epithelial cell marker, E-cadherin, at mRNA and protein expression levels compared with the PQ group. Treatment with PQ significantly increased Wnt1, low-density lipoprotein receptor-related protein (LRP)5, LRP6 and β-catenin expression levels in A549 cells, while rapamycin significantly inhibited these effects of PQ. Activation of the Wnt signaling pathway using lithium chloride attenuated the inhibitory effects of rapamycin on PQ-induced EMT. In conclusion, rapamycin protects against PQ-induced pulmonary EMT via the Wnt/β-catenin signaling pathway.

Filamin A (FLNA) regulates autophagy of bladder carcinoma cell and affects its proliferation, invasion and metastasis

PURPOSE

This research intended to explore the effect of FLNA on cell proliferation, invasion and migration in bladder carcinoma (BC).

METHODS

Microarray analysis was performed with the TCGA data, and the results were confirmed on 20 paired BC tissues and adjacent tissues using qRT-PCR and immunohistochemistry. Transmission electron microscope (TEM) and cell fluorescence assay were used to observe the quantity of autophagosomes. The expression of autophagy-related protein (LC3-I/II, p62) was detected by western blot. Cell proliferation was detected using CCK-8 and colony formation. The invasion and migration ability of the cell were tested by transwell and wound-healing assay. Tumor xenograft in BALB/c nude mice and HE staining were utilized to probe into the effects of FLNA-induced regulation of volume, weight and metastasis of tumors.

RESULTS

We confirmed that FLNA was down-regulated in BC tissues. TEM and fluorescence analysis proved that FLNA overexpression promoted autophagy in BC cells. Colony formation assay and CCK-8 experiment showed that FLNA overexpression suppressed the proliferation of BC cells. In addition, FLNA blocked cell cycle and promoted apoptosis of BC cell. Transwell assay and wound-healing assay further proved that FLNA suppressed invasion and migration ability in BC cell. Meanwhile, in vivo study indicated that FLNA inhibited the tumor growth.

CONCLUSION

Overexpression of FLNA suppressed the proliferation, migration and invasion of the BC cell, suggesting the potential role of FLNA in clinical treatment.

Cordycepin stimulates autophagy in macrophages and prevents atherosclerotic plaque formation in ApoE-/- mice

Autophagy in macrophages plays a key role in the pathogenesis and progression of atherosclerosis and has become a potential therapeutic target. Here we show that cordycepin (Cpn), a natural derivative of adenosine, markedly reduced atherosclerotic plaque and ameliorated associated symptoms such as dyslipidemia, hyperglycemia and inflammation in ApoE^-/- mice. Supplementation of Cpn dose-dependently inhibited oxLDL-elicited foam cell formation and modulated intracellular cholesterol homeostasis by inhibiting cholesterol uptake and promoting cholesterol efflux in RAW264.7 macrophages. Notably, Cpn exhibited significant stimulating effect on macrophage autophagy, as estimated by western blotting, immunofluorescent staining and autophagic vacuoles observation by transmission electron microscopy. The inhibitive effects of Cpn on foam cell formation were dramatically deteriorated in the presence of various autophagy inhibitors, suggesting that autophagy participate, at least in part, in the atheroprotective role of Cpn. Further investigations using different autophagy inhibitors and specific siRNAs for AMP-activated protein kinase (AMPK) gamma1 subunit indicated that Cpn may stimulate macrophage autophagy through AMPK-mTOR pathway. Together, our results demonstrated Cpn as a potential therapeutic agent for the prevention and treatment of atherosclerosis, and the autophagic activity presents a novel mechanism for Cpn-mediated atheroprotection.