Autophagy Apoptosis Research Articles

Total Flavonoids of Aurantii Fructus Immaturus Regulate miR-5100 to Improve Constipation by Targeting Fzd2 to Alleviate Calcium Balance and Autophagy in Interstitial Cells of Cajal.

Aurantii Fructus Immaturus total flavonoids (AFIF) is the main effective fraction extracted from AFI, which has a good effect on promoting gastrointestinal motility. This study aimed to investigate AFIF which regulates miR-5100 to improve constipation symptoms in mice by targeting Frizzled-2 (Fzd2) to alleviate interstitial cells of Cajal (ICCs) calcium ion balance and autophagy apoptosis. The constipated mouse model was induced by an antibiotic suspension, and then treated with AFIF. RNA-seq sequencing, luciferase assay, immunofluorescence staining, transmission electron microscopy, ELISA, flow cytometry, quantitative polymerase chain reaction (PCR), and Western blot were applied in this study. The results showed that AFIF improved constipation symptoms in antibiotic-induced constipated mice, and decreased the autophagy-related protein Beclin1 levels and the LC3-II/I ratio in ICCs. miR-5100 and its target gene Fzd2 were screened as key miRNAs and regulator associated with autophagy. Downregulation of miR-5100 caused increased expression of Fzd2, decreased proliferation activity of ICCs, increased apoptotic cells, and enhanced calcium ion release and autophagy signals. After AFIF treatment, miR-5100 expression was upregulated and Fzd2 was downregulated, while autophagy-related protein levels and calcium ion concentration decreased. Furthermore, AFIF increased the levels of SP, 5-HT, and VIP, and increased the expression of PGP9.5, Sy, and Cx43, which alleviated constipation by improving the integrity of the enteric nervous system network. In conclusion, AFIF could attenuate constipation symptoms by upregulating the expression of miR-5100 and targeting inhibition of Fzd2, alleviating calcium overload and autophagic death of ICCs, regulating the content of neurotransmitters, and enhancing the integrity of the enteric nervous system network.

The role of HIF-1α-mediated autophagy in ionizing radiation-induced testicular injury.

Testis, as a key organ for maintaining male fertility, are extremely sensitive to ionizing radiation (IR). IR-induced testicular dysfunction and infertility are common adverse effects of radiation therapy in patients with pelvic cancer. To study the phenotype and mechanism of IR-induced testicular injury, the mice were irradiated with different radiation doses (0, 2 and 5Gy) below the semi-lethal dose for one month. Our present results showed that testicular weight and the serum testosterone levels significantly decreased with the structural injury of the testis in an IR dose-dependent manner, indicating that IR caused not only the structural damage of the testis, but also the functional damage. Further analysis by TUNEL staining and Western blotting found that IR induced the apoptosis in a dose-dependent manner as indicated by increased expressions of cleaved caspase3, p53 and Bax on Day 15 after IR treatment. Combined with significantly increased oxidative stress, these results indicated that IR-induced testicular damage may be a long-term, progressively aggravated process, accompanied by apoptosis. Given the role of autophagy in apoptosis, the present study also detected and analyzed the localization and expressions of autophagy-related proteins LC-3I/II, beclin1, p62 and Atg12 in testicular cells, and found that LC-3II, beclin1 and Atg12 expressions significantly increased in the testicular cells of mice irradiated with 2Gy and 5Gy, while p62 expression significantly decreased with 5Gy, implying autophagy was involved in the apoptosis of testicular cells induced by IR. Furthermore, the expressions of HIF-1α and BNIP3 were significantly enhanced in the testis cells of mice irradiated with 2Gy and 5Gy, suggesting the potential role of HIF-1α/BNIP3-mediated autophagy in the apoptosis of testicular cells induced by IR. Taken together, our findings demonstrated that HIF-1α/BNIP3-mediated autophagy not only plays a protective effect on the testicular cells of mice irradiated with 2Gy, but also induces the apoptosis of the testicular cells of mice irradiated with 5Gy, indicating the double effects on apoptosis, which will help us further understanding the molecular mechanisms of IR-induced testicular injury, and will facilitate us further studies on testicular radioprotection.

BECLIN-1-Mediated Autophagy Suppresses Silica Nanoparticle-Induced Testicular Toxicity via the Inhibition of Caspase 8-Mediated Cell Apoptosis in Leydig Cells.

Accumulation of silica nanoparticles (SNPs) in the testes leads to male reproductive toxicity. However, little is known about the effect and mechanistic insights of SNP-induced autophagy on apoptosis in Leydig cells. In this study, we aimed to verify the role of SNP-induced autophagy in apoptosis and explore the possible underlying mechanism in mouse primary Leydig cells (PLCs). H&E staining showed that SNPs changed the histological structures of the testes, including a reduction in the Leydig cell populations in vivo. CCK-8 assay showed that SNPs decreased cell viability, and flow cytometry showed that SNPs increased cell apoptosis, both in a dose-dependent manner in vitro. Additionally, Western blotting further found that SNPs activated autophagy by an increase in BECLIN-1, ATG16L, and LC3-II levels and promoted the intrinsic pathway of apoptosis by an increase in the BAX/BCL-2 ratio, cleaved the caspase 8 and caspase 3 levels. Furthermore, autophagy decreased SNP-induced apoptosis via regulation of the caspase 8 level combined with rapamycin, 3-methyladenine, and chloroquine. BECLIN-1 depletion increased the caspase 8 level, leading to an increase in SNP-induced cell apoptosis. Collectively, this evidence demonstrates that SNPs activated BECLIN-1-mediated autophagy, which prevented SNP-induced testicular toxicity via the inhibition of caspase 8-mediated cell apoptosis in Leydig cells.

Interactions between Endoplasmic Reticulum Stress and Autophagy: Implications for Apoptosis and Neuroplasticity-Related Proteins in Palmitic Acid-Treated Prefrontal Cells.

Lipotoxicity of palmitic acid (PA) or high-fat diets has been reported to increase endoplasmic reticulum (ER) stress and autophagy in peripheral tissue as well as apoptotic cell death. It also can lead to an AD-like pathological pattern. However, it has been unknown that PA-induced ER stress and autophagy are involved in the regulation of neuroplastic abnormalities. Here, we investigated the roles of ER stress and autophagy in apoptosis and neuroplasticity-related protein expression in PA-treated prefrontal cells. Prefrontal cells dissected from newborn Sprague-Dawley rats were treated with PA compound with ER stress inhibitor 4-phenylbutyric acid (4-PBA) and autophagy inhibitor 3-methyladenine (3-MA) or PA alone. PA promoted ER stress and autophagy and also cause apoptosis as well as a decline in the expression of neuroplasticity-related proteins. Inhibition of ER stress decreased the expressions of neuroplasticity-related proteins and reduced autophagy activation and apoptosis in PA-treated prefrontal cells. Inhibition of autophagy exacerbated apoptosis and enhanced ER stress in PA-treated prefrontal cells. The present study illustrated that both ER stress and autophagy could be involved in apoptosis and decreased neuroplasticity-related proteins, and the interaction between ER stress and autophagy may play a critical role in apoptosis in PA-treated prefrontal cells. Our results provide new insights into the molecular mechanisms in vitro of lipotoxicity in obesity-related cognitive dysfunction.

The relationship between endoplasmic reticulum stress and autophagy in apoptosis of BEAS-2B cells induced by cigarette smoke condensate.

Cigarette smoke (CS) is one of the severe risk factors for the development of the pulmonary disease. However, the underlying mechanisms, especially the CS-induced the human bronchial epithelial cells (BEAS-2B) apoptosis related to endoplasmic reticulum stress (ERS) and autophagy, remains to be studied. This study aims to investigate the relationship between ERS and autophagy in apoptosis induced by CS condensate (CSC). BEAS-2B cells were stimulated with 0.02, 0.04 and 0.08mg/ml CSC for 24h to detect the ERS, autophagy and apoptosis. Then, ERS and autophagy of BEAS-2B cells were inhibited, respectively, by using 4-PBA and 3-MA, and followed by CSC treatment. The results showed that CSC decreased cell viability, increased cell apoptosis, elevated cleaved-caspase 3/pro-caspase 3 ratio and Bax expressions, but decreased Bcl-2 expressions. The GRP78 and CHOP expressions and LC3-II/LC3-I ratio were dose-dependently increased. The structure of the endoplasmic reticulum was abnormal and the number of autolysosomes was increased in BEAS-2B cells after CSC stimulation. The LC3-II/LC3-I ratio was decreased after ERS inhibition with 4-PBA, but GRP78 and CHOP expressions were enhanced after autophagy inhibition with 3-MA. CSC-induced apoptosis was further increased, Bax expressions and cleaved-caspase 3/pro-caspase 3 ratio were improved, but Bcl-2 expressions were decreased after 3-MA or 4-PBA treatment. In conclusion, the study indicates that ERS may repress apoptosis of BEAS-2B cells induced by CSC via activating autophagy, but autophagy relieves ERS in a negative feedback. This study provides better understanding and experimental support on the underlying mechanisms of pulmonary disease stimulated by CS.

The delay in cell death caused by the induction of autophagy by P2Et extract is essential for the generation of immunogenic signals in melanoma cells.

P2Et extract obtained from the Caesalpinia spinosa plant is abundant in phenolic compounds such as gallic acid and ethyl gallate and can generate signals to activate the immune response by inducing a mechanism known as immunogenic cell death in murine models of breast cancer and melanoma. Immunogenic cell death involves mechanisms such as autophagy, which can be modulated by various natural compounds, including phenolic compounds with a structure similar to those found in P2Et extract. Here, we determine the role of autophagy in apoptosis and the generation of immunogenic signals using murine wild-type B16-F10 melanoma cells and cells with beclin-1 gene knockout. We show that P2Et extract and ethyl gallate induced autophagy, partially protecting tumor cells from death and promoting calreticulin exposure and the release of ATP. Although ethyl gallate showed a mechanism similar to that of P2Et, the induction of apoptosis and immunogenic signals was significantly weaker. In contrast, gallic acid-induced autophagy acted by blocking autophagic flux, which was associated with increased cell death. However, this compound did not induce any of the immunogenic death signals evaluated. Therefore, the complex extract has greater antitumor potential than isolated compounds. Here, we show that inducing autophagic flux with P2Et protects cancer cells from cell death and that this delay in cell death is required for the generation of immunogenic signals.

Effect of DL-3-n-butylphthalide on cognitive function and the regulating role of Nrf2/SIRT3 signaling pathway in vascular dementia mice

Objective To investigate the effects of butylphthalide(NBP) on cognitive function and Nrf2 / SIRT3 signal pathway in vascular dementia (VD) mice. Methods Wild-type mice (Nrf2+ /+ ) were divided into sham group, model group (VD group), butylphthalide treatment group (Nrf2+ /+ NBP group), and Nrf2 gene knockout mice (Nrf2-/-) were divided into Nrf2-/-model group (Nrf2-/-VD group) and Nrf2-/-treatment group (Nrf2-/-NBP group). Both the model group and the treatment group were repeated.The bilateral common carotid arteries were ligated three times to establish a mouse model of cognitive dysfunction caused by cerebral ischemia-reperfusion.The sham group only isolated the bilateral common carotid arteries and threaded the wires, but did not block blood flow.Morris water maze experiment was used to analyze the cognitive function of mice.HE staining was used to observe the changes of neuron morphology and structure in CA1 region of hippocampus, and immunohistochemical analysis was used to analyze the positive expression of caspase 3 and caspase 9 in mouse CA1 region of hippocampus.Western blot was used to detect mouse hippocampus Nrf2, p62, LC3, SIRT3 protein expression. Results (1) In Morris water maze experiment: compared with VD group, the escape latency of Sham group and Nrf2+ /+ NBP group was significantly shorter on the 5th day ((20.69±8.91) s, (7.58±9.47)s, (8.41±12.20)s; q=3.58, 5.07, both P 0.05). (2) Pathological results showed that, compared with VD group, the damage of pyramidal neurons in CA1 area of hippocampus in Sham group and Nrf2+ /+ NBP group was lighter, and that in Nrf2-/- VD group was more serious, and the improvement of neuron morphology was not obvious after NBP treatment.(3) The expression of apoptosis: compared with VD group, the expression of caspase-3 and caspase-9 in the CA1 area of hippocampus in Sham group and Nrf2+ /+ NBP group were significantly lower, and those in Nrf2-/-VD group were significantly higher (t=3.48, 2.95, 3.46, 2.93, -2.99, -3.77, all P 0.05). (4) Expression of related proteins: compared with VD group, Nrf2, SIRT3, p62 protein expression increased, LC3II/I ratio decreased in Nrf2+ /+ NBP group(t=-3.24, -4.04, -4.03, 3.62, all P<0.01); Nrf2, LC3II/ I ratio decreased, SIRT3, p62 protein expression increased in Sham group(t=3.44, 4.72, -3.52, -4.19, all P<0.01); Nrf2, SIRT3, p62 protein expression decreased and LC3II/I ratio increased in Nrf2-/-VD group(t=9.14, 4.20, 4.30, -3.78, all P<0.01); Compared with Nrf2-/- NBP, the expression of Nrf2, SIRT3, p62 decreased, and LC3II/I ratio increased in Nrf2-/-VD group(t=2.40, 3.24, 1.21, -1.16, all P<0.01). The expression of Nrf2, SIRT3, p62 protein in Nrf2+ /+ NBP group increased, and the ratio of LC3II/ I decreased (t=-3.29, -5.00, 6.24, all P<0.01). Conclusion Butylphthalide can reduce the apoptotic damage in hippocampus of VD mice and improve cognitive dysfunction caused by repeated ischemia-reperfusion injury.Regulating Nrf2 / SIRT3 pathway to inhibit hippocampal neuronal apoptosis and autophagy may be its role mechanism. Key words: Butylphthalide(NBP); Vascular dementia; Nrf2; SIRT3; Apoptosis autophagy

Estrogen deficiency induces memory loss via altered hippocampal HB-EGF and autophagy

Estrogen deficiency reduces estrogen receptor-alpha (ERα) and promotes apoptosis in the hippocampus, inducing learning-memory deficits; however, underlying mechanisms remain less understood. Here, we explored the molecular mechanism in an ovariectomized (OVX) rat model, hypothesizing participation of autophagy and growth factor signaling that relate with apoptosis. We observed enhanced hippocampal autophagy in OVX rats, characterized by increased levels of autophagy proteins, presence of autophagosomes and inhibition of AKT-mTOR signaling. Investigating upstream effectors of reduced AKT-mTOR signaling revealed a decrease in hippocampal heparin-binding epidermal growth factor (HB-EGF) and p-EGFR. Moreover, 17β-estradiol and HB-EGF treatments restored hippocampal EGFR activation and alleviated downstream autophagy process and neuronal loss in OVX rats. In vitro studies using estrogen receptor (ERα)-silenced primary hippocampal neurons further corroborated the in vivo observations. Additionally, in vivo and in vitro studies suggested the participation of an attenuated hippocampal neuronal HB-EGF and enhanced autophagy in apoptosis of hippocampal neurons in estrogen- and ERα-deficient conditions. Subsequently, we found evidence of mitochondrial loss and mitophagy in hippocampal neurons of OVX rats and ERα-silenced cells. The ERα-silenced cells also showed a reduction in ATP production and an HB-EGF-mediated restoration. Finally in concordance with molecular studies, inhibition of autophagy and treatment with HB-EGF in OVX rats restored cognitive performances, assessed through Y-Maze and passive avoidance tasks. Overall, our study, for the first time, links neuronal HB-EGF/EGFR signaling and autophagy with ERα and memory performance, disrupted in estrogen-deficient condition.

Valproic Acid Enhanced Apoptosis by Promoting Autophagy Via Akt/mTOR Signaling in Glioma

Glioma is the most common malignant tumor in the central nervous system with a poor median survival. Valproic acid (VPA), a widely used antiepileptic drug, has been found to have antitumor effects on gliomas, but its role still has not been determined. In this study, we investigated VPA-induced apoptotic and autophagic effects on human U251 and SNB19 cells by cell counting kit-8 assay, flow cytometry, terminal deoxynucleotidyl transferase-mediated nick end labeling staining, western blots, and immunofluorescence assay in vitro, and then we further explored the role of autophagy in apoptosis by using the selective antagonist MHY1485. The data showed that VPA inhibited U251 and SNB19 glioma cells viability in a dose-dependent and time-dependent manner and induced apoptosis through the mitochondria-dependent pathway in vitro. In addition, VPA activated the Akt/mTOR pathway by decreasing their protein phosphorylation to promote cellular apoptosis. Surprisingly, the mTOR agonist MHY1485, causing a strong elevation of mTOR activity, partially reduced apoptosis ratio, which supposing that the autophagy of VPA is involved in the regulation of apoptosis. These findings suggest that VPA enhanced apoptosis by promoting autophagy via Akt/mTOR signaling in glioma, which could be further evaluated as a reliable therapy for glioma.

SIRT1-mediated FoxOs pathways protect against apoptosis by promoting autophagy in osteoblast-like MC3T3-E1 cells exposed to sodium fluoride.

Fluorine may result in damage to teeth, bones and other body tissues, and is a serious public health problem. SIRT1 deacetylates FOXOs, which brings about apoptosis and autophagy promotion or suppression. Fluorine may induce cell apoptosis, however, the role of autophagy in apoptosis induced by fluorine is still poorly understood, and the interaction between SIRT1 and FOXOs should be further illustrated. Therefore, this study investigated the mechanisms underlying the NaF- induced apoptosis and autophagy in osteoblast-like MC3T3-E1 cells in vitro through activating or inhibiting SIRT1. Via RT-PCR, western blot, flow cytometry assays, fluorescence and laser confocal microscopy, it was found that NaF induced both cell apoptosis and autophagy. Results also showed that NaF up-regulated SIRT1 expression in a dose-dependent manner. The autophagy of MC3T3-E1 was also up- regulated indirectly whilst apoptosis was significantly attenuated when incubated with the SIRT1 activator SRT1720. When SIRT1 inhibitor Ex-527 was used, the latter effects were reversed. Furthermore, SIRT1 increased deacetylation of FoxO1 and promoted the up-regulation of its target substrate Rab7, as well as increase of Bnip3 which was substrate of FoxO3, and we hypothesize that these pathways may cause an increase in autophagic flux and a reduction in apoptosis. In conclusion, SIRT1-induced autophagy enhancement protects against fluoride-induced apoptosis through autophagy induction in MC3T3-E1 cells, which may be associated with a SIRT1-FoxO1-Rab7 axis and a SIRT1-FoxO3-Binp3 axis. The role of SIRT1 in selecting between cell survival and death provides a potential therapeutic strategy in fluorosis.

Abstract 250: Differential Role of Autophagy in Idiopathic versus Ischemic Heart Failure in Humans

Background: Autophagy is an evolutionary conserved process that plays a key role in a variety of physiological and pathological processes. Despite its beneficial role, excessive/insufficient autophagic activity is known to contribute to the pathogenesis of cardiovascular disorders, including ischemia/reperfusion injury and heart failure. However, the differential role of autophagy in idiopathic versus ischemic heart failure remains unknown. Methods: To investigate the role of autophagy and associated apoptosis in idiopathic versus ischemic heart failure, we obtained LV myocardium biopsies from healthy controls (via 3 commercial sources), and from 10 patients with idiopathic and ischemic end-stage heart failure before the insertion of a left ventricular assist devise. The expression of inducers/markers of autophagy (mTOR, phospho-mTOR, LC3-I/II, p62, Beclin-1, autophagy-related genes ATG4B/ATG5) and apoptosis (Bcl-2 and caspase-3) were assessed at the transcript and protein level using quantitative RT-PCR and Western blotting. Results: Autophagy was activated in both idiopathic and ischemic heart failure in comparison to control, as confirmed by a significant reduction in mTOR expression/activation and a 3.4-fold and 2.2-fold increase in LC3 II/I ratio, respectively. An increase in apoptosis, marked by increased caspase3 and Bcl2 expression, was also observed in both groups in comparison to control. Interestingly, autophagy activity—marked by decreased mTOR expression/activation, increased ATG4B, ATG5, and Beclin-1—was significantly higher in idiopathic heart failure, when compared to ischemic heart failure. While we observed increased autophagic activity in idiopathic heart failure, p62 expression was also significantly increased in this group (2.8-fold increase; p&lt;0.05), demonstrating an impairment of autophagic flux in idiopathic versus ischemic heart failure. Conclusions: For the first time, we provide a direct comparision of autophagy and apoptosis in idiopathic versus ischemic heart failure. Our data, demonstrating an excessive yet insufficient autophagic activity in idiopathic heart failure, suggests a differential role of autophagy apoptosis in idiopathic versus ischemia-related heart failure.

Inhibition of autophagy and enhancement of endoplasmic reticulum stress increase sensitivity of osteosarcoma Saos-2 cells to cannabinoid receptor agonist WIN55,212-2.

WIN55,212-2, a cannabinoid receptor agonist, can activate cannabinoid receptors, which has proven anti-tumour effects in several tumour types. Studies showed that WIN can inhibit tumour cell proliferation and induce apoptosis in diverse cancers. However, the role and mechanism of WIN in osteosarcoma are still unclear. In this study, we examined the effect of WIN55,212-2 on osteosarcoma cell line Saos-2 in terms of cell viability and apoptosis. Meanwhile, we further explored the role of endoplasmic reticulum stress and autophagy in apoptosis induced by WIN55,212-2. Our results showed that the cell proliferation of Saos-2 was inhibited by WIN55,212-2 in a dose-dependent and time-dependent manner. WIN55,212-2-induced Saos-2 apoptosis through mitochondrial apoptosis pathway. Meanwhile, WIN55,212-2 can induce endoplasmic reticulum stress and autophagy in Saos-2 cells. Inhibition of autophagy and enhancement of endoplasmic reticulum stress increased apoptosis induced by WIN55,212-2 in Saos-2 cells. These findings indicated that WIN55,212-2 in combination with autophagic inhibitor or endoplasmic reticulum stress activator may shed new light on osteosarcoma treatment. Copyright © 2016 John Wiley & Sons, Ltd.

The signaling involved in autophagy machinery in keratinocytes and therapeutic approaches for skin diseases.

Autophagy is responsible for the lysosomal degradation of proteins, organelles, microorganisms and exogenous particles. Epidermis primarily consists of keratinocytes which functions as an extremely important barrier. Investigation on autophagy in keratinocytes has been continuously renewing, but is not so systematic due to the complexity of the autophagy machinery. Here we reviewed recent studies on the autophagy in keratinocyte with a focus on interplay between autophagy machinery and keratinocytes biology, and novel autophagy regulators identified in keratinocytes. In this review, we discussed the roles of autophagy in apoptosis, differentiation, immune response, survival and melanin metabolism, trying to reveal the possible involvement of autophagy in skin aging, skin disorders and skin color formation. Since autophagy routinely plays a double-edged sword role in various conditions, its functions in skin homeostasis and potential application as a therapeutic target for skin diseases remains to be clarified. Furthermore, more investigations are needed on optimizing designed strategies to inhibit or enhance autophagy for clinical efficacy.

Endoplasmic reticulum stress and autophagy participate in apoptosis induced by bortezomib in cervical cancer cells.

To determine the role of endoplasmic reticulum (ER) stress and autophagy in apoptosis induced by bortezomib in human cervical cancer-derived HeLa cells and CaSki cells. Bortezomib treatment activated apoptosis, evidenced by increased expression of cleaved caspase-3 and cleaved PARP in both HeLa cells and CaSki cells. Bortezomib also induced the loss of the mitochondrial membrane potential, increased the level of ER stress-associated proteins GRP78, ATF4, and CCAAT-enhancer-binding protein homologous protein, and affected the expression of autophagy-related proteins; increasing the levels of LC3-II and ATG5-ATG12 and decreasing the level of p62. When we combined bortezomib with the ER stress activator tunicamycin, or autophagy inhibitors 3-methyladenine or chloroquine, cell growth inhibition and apoptosis were markedly enhanced. Bortezomib activates apoptosis signaling, and activation of ER stress and inhibition of autophagy enhances the cytotoxicity of bortezomib, suggesting that these combination treatments may be potential chemotherapy strategies for treating cervical cancer.

Regulatory role of autophagy in globular adiponectin-induced apoptosis in cancer cells.

Adiponectin, an adipokine predominantly secreted from adipose tissue, exhibits diverse biological responses, including metabolism of glucose and lipid, and apoptosis in cancer cells. Recently, adiponectin has been shown to modulate autophagy as well. While emerging evidence has demonstrated that autophagy plays a role in the modulation of proliferation and apoptosis of cancer cells, the role of autophagy in apoptosis of cancer cell caused by adiponectin has not been explored. In the present study, we demonstrated that globular adiponectin (gAcrp) induces both apoptosis and autophagy in human hepatoma cell line (HepG2 cells) and breast cancer cells (MCF-7), as evidenced by increase in caspase-3 activity, Bax, microtubule-associated protein light chain 3-II (LC3 II) protein levels, and autophagosome formation. Interestingly, gene silencing of LC3B, an autophagy marker, significantly enhanced gAcrp-induced apoptosis in both HepG2 and MCF-7 cell lines, whereas induction of autophagy by rapamycin, an mTOR inhibitor, significantly prevented gAcrp-induced apoptosis in hepatoma cells HepG2. Furthermore, modulation of autophagy produced similar effects on gAcrp-induced Bax expression in HepG2 cells. These results implicate that induction of autophagy plays a regulatory role in adiponectin-induced apoptosis of cancer cells, and thus inhibition of autophagy would be a novel promising target to enhance the efficiency of cancer cell apoptosis by adiponectin.

Radiation-induced autophagy contributes to cell death and induces apoptosis partly in malignant glioma cells.

PurposeRadiation-induced autophagy has been shown to play two different roles, in malignant glioma (MG) cells, cytocidal or cytoprotective. However, neither the role of radiation-induced autophagy for cell death nor the existence of autophagy-induced apoptosis, a well-known cell-death pathway after irradiation, has been verified yet.Materials and MethodsWe observed both temporal and dose-dependent response patterns of autophagy and apoptosis to radiation in MG cell lines. Additionally, we investigated the role of autophagy in apoptosis through knockdown of autophagy-related proteins.ResultsAutophagic activity measured by staining of acidic vesicle organelles and Western blotting of LC-3 protein increased in proportion to radiation dose from day 1 to 5 after irradiation. Apoptosis measured by annexin-V staining and Western blotting of cleaved poly(ADP-ribose) polymerase demonstrated relatively late appearance 3 days after irradiation that increased for up to 7 days. Blocking of pan-caspase (Z-VAD-FMK) did not affect apoptosis after irradiation, but silencing of Atg5 effectively reduced radiation-induced autophagy, which decreased apoptosis significantly. Inhibition of autophagy in Atg5 knockdown cells was shown to be beneficial for cell survival. Stable transfection of GFP-LC3 cells was observed after irradiation. Annexin-V was localized in cells bearing GFP-LC3 punctuated spots, indicating autophagy in immunofluorescence. Some of these punctuated GFP-LC3 bearing cells formed conglomerated spots and died in final phase.ConclusionThese findings suggest that autophagy appears earlier than apoptosis after irradiation and that a portion of the apoptotic population that appears later is autophagy-dependent. Thus, autophagy is a pathway to cell death after irradiation of MG cells.

Role of autophagy in insulin-promoting cisplatin-induced apoptosis in EC9706 cells

Objective To investigate the role of autophagy in apoptosis induced by cisplatin and insulin in human esophageal squamous cells.Methods EC9706 cells were treated with 140 mg/L cisplatin,and cell viability was measured by using methyl thiazol tetrazolium (MTT) assay.The time T1 when the number of living cells reached a plateau was 24 h,then the time T2 was found when cell viability reached a new plateau with the addition of 10 mU/ml insulin after 6 h.At T1 and T2 time points,the cells were stained by Annexin V-fluoresceine isothiocyanate (FITC) apoptosis detection kit and monodansylcadaverine (MDC),respectively.Cell fluorescence was observed qualitatively under a fluorescence microscope,and apoptosis and the fluorescence intensity of MDC were detected quantitatively by using flow cytometry.Western blotting was used to investigate autophagy-related Beclin-1 changes that occurred in the course of treatment.Results (1) Apoptosis ratio of T1 plateau cells [(32.6 ± 4.3) ％] was lower than that of T2 plateau cells [(47.5 ± 5.6) ％] (P ＜ 0.05),and the MDC fluorescence intensity at T1 plateau [(104.9 ± 13.2)] was higher than that at T2 plateau [(82.6 ± 10.3)] significantly (P ＜ 0.05).(2) After co-treatment with insulin,the expression of Beclin-1 was significantly down-regulated (P ＜ 0.0l).Conclusion Inhibition of autophagy by insulin enhances the effect of cisplatin-induced apoptosis in esophageal cancer cells.Insulin is likely to be in this way to realize its chemotherapy sensitization effect. Key words: Esophageal squamous cell carcinoma; Autophagy; Apoptosis; Insulin

Dual PI3K/mTOR inhibitor NVP-BEZ235-induced apoptosis of hepatocellular carcinoma cell lines is enhanced by inhibitors of autophagy

Dysregulation of the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling has been found in several types of human cancer, including hepatocellular carcinoma (HCC). NVP-BEZ235 is a novel, orally bioavailable dual PI3K/mTOR inhibitor that has exhibited promising activity against HCC in preclinical models. Autophagy is a cellular lysosomal degradation pathway essential for the regulation of cell survival and death to maintain homeostasis. This process is negatively regulated by mTOR signaling and often counteracts the efficacy of certain cancer therapeutic agents. In this study, we explored the role of autophagy in apoptosis induced by NVP-BEZ235 in two HCC cell lines, Hep3B and PLC/PRF/5, and identified the mechanism of combinatorial treatment. NVP-BEZ235 was effective in inhibiting the growth of the two HCC cell lines possibly though induction of apoptosis. NVP-BEZ235 also potently increased the expression of LC3-II and decreased the expression of p62, indicating induction of autophagy. When NVP-BEZ235 was used in combination with Atg5 siRNA or the autophagy inhibitor 3-methyladenine (3-MA), enhancement of the inhibitory effects on the growth of HCC cells was detected. In addition, enhanced induction of apoptosis was observed in cells exposed to the combination of NVP-BEZ235 and Atg5 siRNA or 3-MA. Thus, induction of autophagy by NVP-BEZ235 may be a survival mechanism that counteracts its anticancer effects. Based on these data, we suggest a strategy to enhance the anticancer efficacy of BEZ235 by blockade of autophagy. Thus, our study provides a rationale for the clinical development of combinations of NVP-BEZ235 and autophagy inhibitors for the treatment of HCC and other malignancies.

Zyflamend Mediates Therapeutic Induction of Autophagy to Apoptosis in Melanoma Cells

Melanoma is the most aggressive form of skin cancer. The rising incidence of melanoma and its poor prognosis in advanced stages are compelling reasons to identify novel therapeutic agents. Though isolated dietary components such as lycopene, resveratrol, and isothiocyanate compounds have been shown to provide limited protection against cancer development, the use of whole herbs and herbal extracts for the treatment of cancer remains of great interest. As suggested by earlier studies, the antiinflammatory activity of many plants available as intact products or as extracts has long been considered for supplemental therapeutics for cancer. Zyflamend, a unique multiherbal extract preparation, is a promising antiinflammatory agent that has also been suggested to regulate multiple pathways in cancer progression. As Zyflamend contains ingredients that can suppress tumor cell proliferation, invasion, angiogenesis, and metastasis through regulation of inflammatory pathway products, we hypothesized that this preparation might inhibit melanoma proliferation. To test this hypothesis, we studied the effect of Zyflamend on melanoma proliferation. Here, we present that Zyflamend inhibits melanoma growth by regulating the autophagy–apoptosis switch. Based on the responsible molecular mechanisms of Zyflamend, our study highlights the importance of the use of herbal preparations for the prevention and treatment of cancer.

Arginine Deprivation, Autophagy, Apoptosis (AAA) for the Treatment of Melanoma

The majority of melanoma cells do not express argininosuccinate synthetase (ASS), and hence cannot synthesize arginine from citrulline. Their growth and proliferation depend on exogenous supply of arginine. Arginine degradation using arginine deiminase (ADI) leads to growth inhibition and eventually cell death while normal cell which express ASS can survive. This notion has been translated into clinical trial. Pegylated ADI (ADI-PEG20) has shown antitumor activity in melanoma. However, the sensitivity to ADI is different among ASS(-) melanoma cells. We have investigated and reviewed the signaling pathways which are affected by arginine deprivation and their consequences which lead to cell death. We have found that arginine deprivation inhibits mTOR signaling but leads to activation of MEK and ERK with no changes in BRAF. These changes most likely lead to autophagy, a possible mechanism to survive by recycling intracellular arginine. However apoptosis does occur which can be both caspase dependent or independent In order to increase the therapeutic efficacy of this form of treatment, one should consider adding other agent(s) which can drive the cells toward apoptosis or inhibit the autophagic process.