Beclin-1 In Cells Research Articles

Curcumin inhibits pancreatic cancer cell proliferation by regulating Beclin1 expression and inhibiting the hypoxia-inducible factor-1α-mediated glycolytic pathway

Pancreatic cancer has a high degree of malignancy and high mortality. Understanding its biological status can provide more therapeutic targets for the future. The present study was to investigate whether curcumin can inhibit pancreatic cancer cell proliferation by regulating Beclin1 expression and inhibiting the hypoxia-inducible factor-1α (HIF-1α)-mediated glycolytic pathway. Two pancreatic cancer cell lines, PANC-1 and SW1990, were treated with different concentrations of curcumin (0, 20, 40, and 60 µM). Cell viability was detected using the Cell Counting Kit-8 (CCK-8) assay and flow cytometry was performed to determine the apoptosis rate and cell cycle arrest of the pancreatic cancer cells. PANC-1 and SW1990 cells were treated with different concentrations of curcumin under hypoxic conditions for 48 hours to detect the relative expression of the Beclin1 protein. The co-immunoprecipitation (co-IP) method was used to determine whether curcumin could inhibit the interaction between Beclin1 and HIF-1α. The proliferation inhibition rates of PANC-1 cells after exposure to 0, 20, 40, and 60 µM curcumin were 0%, 31.6%, 47.2%, and 63.9%, respectively, and that of SW1990 cells were 0%, 18.8%, 46.3%, and 63.5% respectively. Western blot analyses showed decreased expression of Beclin1 in cells treated with curcumin. The expression of Beclin1 in the nucleus and cytoplasm decreased with increasing concentrations of curcumin. Co-IP results demonstrated that curcumin inhibited the interaction between Beclin1 and HIF-1α. Treatment with the higher doses of curcumin (40 and 60 µM) significantly decreased the protein expression levels of HIF-1α. In addition, the expression levels of Kidney-Specific Cadherin (HSP70, HSP90, and von Hippel-Lindau protein (pVHL) were significantly decreased in pancreatic cancer cells while the expression of prolyl hydroxylase (PHD) and receptor of activated protein kinase C (RACK1) increased significantly. Furthermore, curcumin reduced cellular adenosine triphosphate (ATP) production in a dose-dependent manner. Compared with control pancreatic cancer cells, the expression levels of GLUT1, HK2, LDHA, and PDK1 gradually decreased with increasing curcumin concentrations. Curcumin can inhibit the expression of Beclin1 and HIF-1α in pancreatic cancer cells under anoxic conditions, thereby affecting the glycolysis pathway and inhibiting cell proliferation.

MicroRNA-379-5p targets MAP3K2 to reduce autophagy and alleviate neuronal injury following cerebral ischemia via the JNK/c-Jun signaling pathway.

MicroRNAs (miRNAs) are abundant in neurons and play key roles in the function and development of the nervous system. This study focuses on the function of miR-379-5p in neurological function recovery during ischemic stroke. The expression of miR-379-5p in the serum of patients with ischemic stroke was determined. Human cerebral cortical neuron cells (HCN-2) were subjected to oxygen/glucose deprivation (OGD) to mimic an ischemic stroke in vitro, whereas mice subjected to middle cerebral artery occlusion (MCAO) were used as an animal model. The serum of patients with ischemic stroke and OGD-treated HCN-2 cells displayed a poor expression of miR-379-5p. Upregulation of miR-379-5p reduced the OGD-induced cell damage and decreased the expression of the autophagy marker protein Beclin1 in cells. Rapamycin, an autophagy activator, blocked the protective functions of miR-379-5p. Further, miR-379-5p directly bound to MAP3K2. MAP3K2 activated the JNK/c-Jun signaling pathway and suppressed the neuroprotective events mediated by miR-379-5p. The in vitro results were reproduced in vivo, where upregulation of miR-379-5p reduced neurological impairment and infarct size in MCAO-induced mice. This study suggested that miR-379-5p showed a neuroprotective effect on ischemic stroke and reduced autophagy of neurons through the suppression of MAP3K2 and the JNK/c-Jun axis.

LncRNA-MALAT1 influences myocardial infarction by regulating miR-30a/beclin-1 pathway.

Long non-coding ribonucleic acid-metastasis-associated lung adenocarcinoma transcript 1 (lncRNA-MALAT1) has been confirmed as a key factor involving in various physiological and pathological processes. The present study aims to investigate whether lncRNA-MALAT1 affects the process of myocardial infarction (MI) in rats by regulating the micro RNA (miR-30a)/Beclin-1 (BECN1) pathway. Twelve healthy male Sprague-Dawley rats were randomly selected and equally divided into sham-operation group and MI group. In MI group, a rat model of acute MI (AMI) was established by ligating the left anterior descending coronary artery. Rats in sham-operation group were set as the control. The messenger RNA (mRNA) expression levels of lncRNA-MALAT1, miR-30a, and BECN1 in the infarcted myocardial tissues were detected via real-time fluorescence quantitative polymerase chain reaction (qRT-PCR). The rat myocardial cell line H9c2 was cultured in vitro and then transfected with vectors of lncRNA-MALAT1, miR-30a, and BECN1. After that, qRT-PCR was performed to measure mRNA levels of lncRNA-MALAT1, miR-30a, and BECN1 in H9c2 cells. The protein level of BECN1 in cells was determined via Western blotting (WB) assay. Expression levels of lncRNA-MALAT1 and BECN1 in the rat myocardium of MI group were up-regulated markedly (p<0.01), while miR-30a was down-regulated notably (p<0.01) compared with those in sham-operation group. After H9c2 cells were transfected with overexpression vectors of lncRNA-MALAT1 or miR-30a, expression levels of miR-30a (p<0.01) and BECN1 (p<0.01) were remarkably down-regulated, respectively. LncRNA-MALAT1 up-regulates the expression of BECN1 by binding to miR-30a, thereby increasing the level of cell autophagy after MI.

Lipopolysaccharide regulates the expression of thymocyte differentiation antigen-1 and integrin β3 of lung fibroblasts and inhibit autophagy

Objective To clarify the effect of lipopolysaccharide (LPS) on the expression of thymocyte differentiation antigen-1(Thy-1) and integrin β3 in mouse lung fibroblasts and its relationship with autophagy inhibition. Methods Primary cultured mouse lung fibroblasts were divided into four groups (n=3) based on different concentration of LPS stimulation: PBS control group (Con group), 0.25 mg/L LPS group (LPS0.25 group), 0.50 mg/L LPS group (LPS0.50 group), 1.00 mg/L LPS group (LPS1.00 group). Then the total cellular proteins were extracted. The expression of Thy-1 and integrin β3 were detected by Western blot. The expression of autophagy-related proteins LC3-Ⅱ/Ⅰ and Beclin-1 in cells was compared at 30 h after LPS stimulatin. The formation of autophagic bodies was observed by using transmission electron microscopy. Results Thy-1 protein expression was decreased in lung fibroblasts with increasing concentration of LPS stimulation. Compared with the control group(P<0.05), the level of Thy-1 protein in lung fibroblasts was significantly decreased in 1.00 mg/L LPS group. Integrin β3 protein expression was increased with increasing concentration of LPS stimulation. As a result, the expression leve of integrin in 1.00 mg/L LPS group was significantly higher than the level in control group (P<0.05). At the same time, LPS significantly inhibited the expression of autophagy-related proteins LC3-Ⅱ/Ⅰ(P<0.05) and Beclin-1 (P<0.05) in mouse lung fibroblasts and the formation of autophagic bodies(P<0.05). Conclusions LPS can down-regulate the expression of Thy-1 but up-regulate the expression of integrin β3. It also inhibits the expression of autophagy-related proteins LC3-Ⅱ/Ⅰ, Beclin-1 and the formation of autophagic bodies. This process may be associated with LPS-induced autophagy inhibition of lung fibroblasts and the progress of lung fibrosis. Key words: Lipopolysaccharide; Lung fibroblasts; Autophagy; Thymocyte differentiation antigen-1; Integrin β3

Mitochondrially targeted ceramides preferentially promote autophagy, retard cell growth, and induce apoptosis

C(6)-pyridinium (D-erythro-2-N-[6'-(1''-pyridinium)-hexanoyl]sphingosine bromide [LCL29]) is a cationic mitochondrion-targeting ceramide analog that promotes mitochondrial permeabilization and cancer cell death. In this study, we compared the biological effects of that compound with those of D-erythro-C(6)-ceramide, its non-mitochondrion-targeting analog. In MCF7 cells it was found that C(6)-pyridinium ceramide preferentially promoted autophagosome formation and retarded cell growth more extensively than its uncharged analog. This preferential inhibition of cell growth was also observed in breast epithelial cells and other breast cancer cells. In addition, this compound could promote Bax translocation to mitochondria. This redistribution of Bax in MCF7 cells could be blocked by the pan-caspase inhibitor zVAD-fmk but via a Bid-independent signaling pathway. Moreover, C(6)-pyridinium ceramide-induced translocation of Bax to mitochondria led to mitochondrial permeabilization and cell death. Overall, we show that mitochondrial targeting of C(6)-pyridinium ceramide significantly enhances cellular response to this compound.