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Results for “Apoptosis”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

3-Bromopyruvate and sodium citrate induce apoptosis in human gastric cancer cell line MGC-803 by inhibiting glycolysis and promoting mitochondria-regulated apoptosis pathway

Cancer cells are mainly dependent on glycolysis to generate adenosine triphosphate (ATP) and intermediates required for cell growth and proliferation. Thus, inhibition of glycolysis might be of therapeutic value in antitumor treatment. Our previously studies had found that both 3-bromopyruvate (BP) and sodium citrate (SCT) can inhibit tumor growth and proliferation in vitro and in vivo. However, the mechanism involved in the BP and SCT mediated antitumor activity is not entirely clear. In this work, it is demonstrated that BP inhibits the enzyme hexokinase (HK) activity and SCT suppresses the phosphofructokinase (PFK) activity respectively, both the two agents decrease viability, ATP generation and lactate content in the human gastric cancer cell line MGC-803. These effects are directly correlated with blockage of glycolysis. Furthermore, BP and SCT can induce the characteristic manifestations of mitochondria-regulated apoptosis, such as down-regulation of anti-apoptosis proteins Bcl-2 and Survivin, up-regulation of pro-apoptosis protein Bax, activation of caspase-3, as well as leakage of cytochrome c (Cyt-c). In summary, our results provided evidences that BP and SCT inhibit the MGC-803 cells growth and proliferation might be correlated with inhibiting glycolysis and promoting mitochondria-regulated apoptosis. -- Highlights: •Blockage of glycolysis might be a novel way to anticancer. •Both 3-bromopyruvate and sodium citrate could inhibit glycolysis and regulate mitochondrial pathway in cancer cells. •Both 3-bromopyruvate and sodium citrate would be the novel agents on treatment of gastric cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Activation of PPAR alpha by fenofibrate inhibits apoptosis in vascular adventitial fibroblasts partly through SIRT1-mediated deacetylation of FoxO1

Recent studies demonstrated that the ligand-activated transcription factor peroxisome proliferator-activated receptorα (PPARα) acts in association with histone deacetylase sirtuin 1 (SIRT1) in the regulation of metabolism and inflammation involved in cardiovascular diseases. PPARα activation also participates in the modulation of cell apoptosis. Our previous study found that SIRT1 inhibits the apoptosis of vascular adventitial fibroblasts (VAFs). However, whether the role of PPARα in apoptosis of VAFs is mediated by SIRT1 remains unknown. In this study, we aimed to determine the effect of PPARα agonist fenofibrate on cell apoptosis and SIRT1 expression and related mechanisms in ApoE{sup −/−} mice and VAFs in vitro. We found that fenofibrate inhibited cell apoptosis in vascular adventitia and up-regulated SIRT1 expression in aorta of ApoE{sup −/−} mice. Moreover, SIRT1 activator resveratrol (RSV) further enhanced these effects of fenofibrate. In vitro study showed that activation of PPARα by fenofibrate inhibited TNF-α-induced cell apoptosis and cell cycle arrest in VAFs. Meanwhile, fenofibrate up-regulated SIRT1 expression and inhibited SIRT1 translocation from nucleus to cytoplasm in VAFs stimulated with TNF-α. Moreover, the effects of fenofibrate on cell apoptosis and SIRT1 expression in VAFs were reversed by PPARα antagonist GW6471. Importantly, treatment of VAFs with SIRT1 siRNA or pcDNA3.1(+)-SIRT1 showed that the inhibitory effect of fenofibrate on cell apoptosis in VAFs through SIRT1. On the other hand, knockdown of FoxO1 decreased cell apoptosis of VAFs compared with fenofibrate group. Overexpression of FoxO1 increased cell apoptosis of VAFs compared with fenofibrate group. Further study found that fenofibrate decreased the expression of acetylated-FoxO1 in TNF-α-stimulated VAFs, which was abolished by SIRT1 knockdown. Taken together, these findings indicate that activation of PPARα by fenofibrate inhibits cell apoptosis in VAFs partly through the SIRT1-mediated deacetylation of FoxO1. - Highlights: • Fenofibrate inhibits apoptosis and increases SIRT1 expression in vivo and in vitro. • Fenofibrate inhibits cell apoptosis in VAFs through SIRT1. • Fenofibrate inhibits apoptosis through SIRT1-mediated deacetylation of FoxO1. • Fenofibrate inhibits apoptosis and increases SIRT1 expression via PPARα activation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Tacrolimus induces fibroblasts apoptosis and reduces epidural fibrosis by regulating miR-429 and its target of RhoE

Tacrolimus (FK506) has been demonstrated to reduce epidural fibrosis. However, the detailed mechanism of action has not been elucidated. Aberrant miR-429 is involved in many diseases. The aim of this study was to describe the exact mechanism of FK506 induced apoptosis in fibroblasts and the prevention of epidural fibrosis. FK506 induced fibroblast apoptosis was evaluated using CCK-8 assays, flow cytometry, and western blotting. The expression of miR-429 in fibroblasts treated with FK506 was determined by RT-qPCR. Additionally, luciferase activity assays were used to determine the target relationship between miR-429 and RhoE. Flow cytometry and western blot analysis were used to determine the effects of FK506 and miR-429 on fibroblast apoptosis. The effects of FK506 and RhoE on fibroblast apoptosis were determined by CCK-8 assay, flow cytometry, and western blotting. We also evaluate the effects of FK506 and miR-429 on epidural fibrosis in rats by using histological analysis and TUNEL-staining. The results revealed FK506 induces fibroblast apoptosis and significantly downregulates miR-429 expression in fibroblasts. Additionally, miR-429 downregulation caused the apoptosis of fibroblasts. The luciferase activity assay confirmed that RhoE is a direct target of miR-429 and RhoE promotes fibroblast apoptosis. The rat model demonstrated miR-429 inhibition promotes fibroblast apoptosis and epidural fibrosis, which is consistent with the results of FK506 treatment. Our study demonstrates that FK506 induces fibroblast apoptosis and reduces epidural fibrosis by regulating miR-429 expression and its target of RhoE. - Highlights: • FK506 could inhibit the proliferation and induce the apoptosis of human fibroblast. • FK506 could downregulate the expression of miR-429 and RhoE is a target gene of miR-429. • Inhibits the function of RohE could reduce the apoptosis of human fibroblast after treatment of FK506. • Inhibits the miR-429 function could inhibit proliferation and induce apoptosis of fibroblast and reduce epidural fibrosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

The role of cPLA2 in Methylglyoxal-induced cell apoptosis of HUVECs

Methylglyoxal (MGO), a highly reactive dicarbonyl compound, is mainly formed as a byproduct of glycolysis. Elevated MGO level is known to induce apoptosis of vascular endothelial cells, which is implicated with progression of atherosclerosis and diabetic complications. However, the underlying mechanisms have not been exhaustively investigated yet. Here, we further characterized the mechanisms how MGO induced apoptosis in human umbilical vein endothelial cells (HUVECs). Our data revealed that cytosolic phospholipase A2 (cPLA2) played an important role in MGO-induced cell apoptosis. It was found that MGO could increase both the activity and expression of cPLA2. Inhibition of cPLA2 by Pyrrophenone (PYR) or siRNA significantly attenuated the MGO-induced apoptosis. Additionally, MGO time-dependently decreased the phosphorylation of nuclear factor κB (NF-κB). Pretreatment of the cells with NF-κB inhibitor, BAY11-7082, further increased MGO-induced apoptosis of HUVECs, indicating that NF-κB played a survival role in this MGO-induced apoptosis. Furthermore, in the presence of si-cPLA2 or PYR, MGO no longer decreased NF-κB phosphorylation. Beyond that, the antioxidant N-acetyl cysteine (NAC) could reverse the changes of both cPLA2 and NF-κB caused by MGO. p38, the upstream of cPLA2, was also significantly phosphorylated by MGO. However, p38 inhibitor failed to reverse the apoptosis induced by MGO. This study gives an important insight into the downstream signaling mechanisms of MGO, cPLA2-NF-κB, in endothelial apoptosis. - Highlights: • cPLA2 participated in MGO-induced HUVECs apoptosis. • Inhibition of NF-κB was involved in MGO-cPLA2-mediated cell apoptosis. • Antioxidant NAC attenuated MGO-induced cPLA2 activation and cell apoptosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Hyperglycemia-induced Bcl-2/Bax-mediated apoptosis of Schwann cells via mTORC1/S6K1 inhibition in diabetic peripheral neuropathy

Highlights: • Activation of mTOR prevents high glucose-induced apoptosis in Schwann cells. • The mTORC1 regulates high glucose-induced mitochondria-controlled apoptosis in Schwann cells. • Phosphorylation of S6K1 as mTORC1 downstream target affects high glucose-induced cell apoptosis in Schwann cells. Schwann cell apoptosis is one of the characteristics of diabetic peripheral neuropathy (DPN). The mammalian target of rapamycin (mTOR) is a multifunctional signaling pathway that regulates cell apoptosis in various types of tissues and cells. To investigate whether the mTOR pathway is involved in cell apoptosis in the Schwann cells of DPN, diabetic mice and rat Schwann cells (RSC96) were chosen to detect phospho-mTOR (Ser 2448), phospho-S6K1 (Thr 389), phospho-4EBP1 (Thr 37/46), Bcl-2, Bax and cleaved caspase-3 by diverse pathological and biological techniques. The results showed that phospho-mTOR (Ser 2448) was decreased in the sciatic nerves of diabetic mice, concomitant with decreased Bcl-2, increased Bax, cleaved caspase-3 and cell apoptosis. In addition, high glucose treatment for 72 h caused a 35.95% decrease in the phospho-mTOR (Ser 2448)/mTOR ratio, a 65.50% decrease in the phospho-S6K1 (Thr 389)/S6K1 ratio, a 3.67-fold increase in the Bax/Bcl-2 ratio and a 1.47-fold increase in the cleaved caspase-3/caspase-3 ratio. Furthermore, mTORC1 inhibition, rather than mTORC2 inhibition, resulted in mitochondrial controlled apoptosis in RSC96 cells by silencing RAPTOR or RICTOR. Again, suppression of the mTORC1 pathway by a chemical inhibitor led to mitochondrial controlled apoptosis in cultured RSC96 cells in vitro. By contrast, activation of the mTORC1 pathway with MHY1485 prevented decreased phospho-S6K1 (Thr 389) levels caused by high glucose and cell apoptosis. Additionally, constitutive activation of S6K1 avoided high glucose-induced cell apoptosis in RSC96 cells. In summary, our findings suggest that activating mTORC1/S6K1 signaling in Schwann cells may be a promising strategy for the prevention and treatment of DPN.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Activation of Wnt3α/β-catenin signal pathway attenuates apoptosis of the cerebral microvascular endothelial cells induced by oxygen-glucose deprivation

Brain microvascular endothelial cells (BMECs) play vital roles in cerebral ischemia, during which many signal pathways mediate BMECs apoptosis. In this study, we explored the potential role of Wnt3α/β-catenin signal in BMECs apoptosis induced by ischemia. Here, we found that oxygen-glucose deprivation (OGD) could induce apoptosis of BMECs with Wnt3a mRNA expression decrease. Meanwhile, activation Wnt3a/β-catenin signal with exogenous Wnt3α protein (100 ng/ml) or Lithium Chloride (LiCl, 4 mM) decreased significantly apoptosis of BMECs induced by OGD with increasing expression of Bcl-2 in the whole cell and β-catenin in the nucleus. But, inhibition Wnt3a/β-catenin signal with DKK1 (100 ng/ml) or 2.4-diamino quinazoline (DQ, 0.2 μM) increased apoptosis of BMECs with decreasing expression of Bcl-2. These results suggest that activation Wnt3α/β-catenin signal attenuate apoptosis of BMECs induced by ischemia. - Highlights: • OGD induced BMECs apoptosis with Wnt3a mRNA expression decrease. • Activation Wnt signal reduced BMECs apoptosis with increasing Bcl-2 and β-catenin. • Inhibition Wnt signal increased BMECs apoptosis with decreasing Bcl-2. • Wnt3α/β-catenin signal attenuates apoptosis of BMECs induced by ischemia.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

TUG1 promotes lens epithelial cell apoptosis by regulating miR-421/caspase-3 axis in age-related cataract

Background: Age-related cataract is among the most common chronic disorders of ageing and the apoptosis of lens epithelial cells contributes to non-congenital cataract development. We amid to explore the role of TUG1 and miR-421 in the age-related cataract. Methods: The expression level of TUG1, miR-421 and caspase-3 were detected by RT-qPCR. The apoptotic-related protein, caspase-3, Bax and blc-2 were analyzed by western blot. We performed ultraviolet (UV) irradiation to induce SAR01/04 cell apoptosis which was analyzed by flow cytometry. RIP pull-down and luciferase reporter assay were used to verified the combination and regulating among TUG1, miR-421 and caspase-3. Results: Here, we observed that the expression level of TUG1 and caspase-3 in the anterior lens capsules of age-related cataract were significantly higher and miR-421 was significantly lower than that in the normal anterior lens capsules. The apoptosis-related protein, caspase-3, Bax and blc-2 were abnormal expression in the anterior lens capsules of age-related cataract tissue. Our data showed that the expression level of TUG1 and caspase-3 and cell apoptosis rate in SAR01/04 cells treated with UV irradiation was remarkably higher than that in the control. TUG1 negatively regulated miR-421 expression and promoted UV irradiation-induced SAR01/04 cell apoptosis. However, miR-421 inhibitor and pcDNA-caspase-3 could reverse the action of the SRA01/04 cell apoptosis by si-TUG1, which suggested TUG1 promoted UV irradiation-induced apoptosis through downregulating miR-421 expression. Furthermore, this study confirmed TUG1 could been in combination with miR-421, and TUG1 and caspase-3 were both a directly target of miR-421. Conclusion: TUG1 modulated lens epithelial cell apoptosis through miR-421/caspase-3 axis. These findings will offer a novel insight into the pathogenesis of cataract. - Highlights: • TUG1 is increased in age-related cataract and UV irradiation-induced SAR01/04 cell. • Highly expressed TUG1 promotes UV irradiation-induced SAR01/04 cell apoptosis. • TUG1 and caspase-3 are both a direct target of miR-421. • MiR-421 inhibitor increases si-TUG1-inhibited SAR01/04 cells apoptosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Traditional Chinese medication Tongxinluo attenuates apoptosis in ox-LDL-stimulated macrophages by enhancing Beclin-1-induced autophagy

Highlights: • TXL attenuates ox-LDL-impaired apoptosis in THP-1 macrophages. • TXL attenuates ox-LDL-impaired apoptosis in THP-1 macrophages by enhancing autophagy. • TXL treatment inhibits macrophage apoptosis by enhancing macrophage autophagy in advanced atherosclerotic plaques. • TXL stabilizes atherosclerotic plaques by attenuating macrophage apoptosis and enhancing Beclin-1-induced autophagy. In advanced atherosclerosis, a large number of necrotic core increases plaque vulnerability, which leads to the occurrence of acute atherothrombotic cardiovascular events. Macrophage apoptosis plays an important role in secondary necrosis. The present study aimed to examine and describe the effect of the traditional Chinese medication Tongxinluo (TXL) on macrophage apoptosis in advanced atherosclerotic plaques and to explore its mechanism. By observing the effect of TXL on ox-LDL-stimulated macrophage apoptosis, it was shown that TXL significantly inhibited ox-LDL-induced apoptosis of macrophages by enhancing autophagy. Therapeutic mechanism of TXL included increasing the expression of Beclin-1 and improving the dissociation of Bcl-2-Beclin-1 Complex. Apolipoprotein E knockout (apoE−/−) mice with a high fat diet were divided into four groups: saline group (Saline gavage), low dose TXL group (0.38 g/kg/d, gavage), medium dose TXL group (0.75 g/kg/day, gavage), and high dose TXL group (1.5 g/kg/day, gavage). 4 weeks after carotid-artery surgery, lentiviral of Beclin-1 silencing was injected through the tail vein. TXL treatment significantly reduced macrophage apoptosis dose-dependently and the result was blocked by Beclin-1 silencing. In addition, the increased Lc3b dots by TXL almost localized to macrophages in advanced atherosclerotic plaque. Compared with the same dose of TXL shBeclin-1 group, plaque area and vulnerability index of TXL groups decreased. The anti-apoptosis effects of TXL on atherosclerosis was related to the improvement of autophagy via Beclin-1.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Caspase-mediated cleavage of X-ray repair cross-complementing group 4 promotes apoptosis by enhancing nuclear translocation of caspase-activated DNase

Highlights: • XRCC4 and its cleavage by caspases promote staurosporine-induced apoptosis. • XRCC4 cleavage enhances staurosporine-induced nuclear import of CAD. • XRCC4 facilitates SRPK1-mediated SRSF1 activation, which reduces ICAD-S mRNA. • XRCC4-dependent reduction of ICAD-S stimulates the nuclear import of CAD. • XRCC4 also enhances apoptosis triggered by paclitaxel or vincristine. X-ray repair cross-complementing group 4 (XRCC4), a repair protein for DNA double-strand breaks, is cleaved by caspases during apoptosis. In this study, we examined the role of XRCC4 in apoptosis. Cell lines, derived from XRCC4-deficient M10 mouse lymphoma cells and stably expressing wild-type XRCC4 or caspase-resistant XRCC4, were established and treated with staurosporine (STS) to induce apoptosis. In STS-induced apoptosis, expression of wild-type, but not caspase-resistant, XRCC4 in XRCC4-deficient cells enhanced oligonucleosomal DNA fragmentation and the appearance of TUNEL-positive cells by promoting nuclear translocation of caspase-activated DNase (CAD), a major nuclease for oligonucleosomal DNA fragmentation. CAD activity is reportedly regulated by the ratio of two inhibitor of CAD (ICAD) splice variants, ICAD-L and ICAD-S mRNA, which, respectively, produce proteins with and without the ability to transport CAD into the nucleus. The XRCC4-dependent promotion of nuclear import of CAD in STS-treated cells was associated with reduction of ICAD-S mRNA and protein, and enhancement of phosphorylation and nuclear import of serine/arginine-rich splicing factor (SRSF) 1. These XRCC4-dependent, apoptosis-enhancing effects were canceled by depletion of SRSF1 or SR protein kinase (SRPK) 1. In addition, overexpression of SRSF1 in XRCC4-deficient cells restored the normal level of apoptosis, suggesting that SRSF1 functions downstream of XRCC4 in activating CAD. This XRCC4-dependent, SRPK1/SRSF1-mediated regulatory mechanism was conserved in apoptosis in Jurkat human leukemia cells triggered by STS, and by two widely used anti-cancer agents, Paclitaxel and Vincristine. These data imply that the level of XRCC4 expression could be used to predict the effects of apoptosis-inducing drugs in cancer treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Long noncoding RNA FTX regulates cardiomyocyte apoptosis by targeting miR-29b-1-5p and Bcl2l2

Highlights: • LncRNA FTX inhibits apoptosis in cardiomyocytes. • miR-29b-1-5p regulates apoptosis by targeting Bcl2l2 in cardiomyocytes. • FTX sponges and regulates the activity of miR-29b-1-5p. • FTX regulates apoptosis by targeting miR-29b-1-5p and Bcl2l2. Cardiomyocyte apoptosis correlates with the pathogenesis of heart disease. Long noncoding RNA (LncRNA) emerges as a class of noncoding RNAs that regulate gene expression and participate in various cellular processes. However, the role of lncRNAs in cardiomyocyte apoptosis remains to be elucidated. In our study, we found that lncRNA FTX is significantly down-regulated upon ischemia/reperfusion injury and hydrogen peroxide treatment. Enhanced expression of FTX inhibits cardiomyocyte apoptosis induced by hydrogen peroxide. miR-29b-1-5p was found to interact with FTX and regulate the expression of Bcl2l2. Inhibition of miR-29b-1-5p attenuated cardiomyocyte apoptosis upon hydrogen peroxide treatment. We then found that FTX functions as endogenous sponge for miR-29b-1-5p and regulates the activity of miR-29b-1-5p. The results demonstrate that FTX regulates cardiomyocyte apoptosis through modulating the expression of Bcl2l2 which is mediated by miR-29b-1-5p. Our findings reveal a novel regulatory model which is composed of FTX, miR-29b-1-5p and Bcl2l2. Manipulating of their levels may become a new approach to tackling cardiomyocyte apoptosis related heart diseases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Tisp40 deficiency attenuates renal ischemia reperfusion injury induced apoptosis of tubular epithelial cells

Renal ischemia reperfusion (IR) is a major cause of acute kidney injury (AKI) and no effective treatments have been established. Tisp40 is a transcription factor of the CREB/ATF family and involves in cell apoptosis, proliferation and differentiation, but its role in renal IR remains unknown. Here, we investigated the role of Tisp40 in renal IR injury. In vivo, Tisp40 knockout (KO) and wild-type (WT) mice were subjected to thirty minutes of bilateral renal ischemia and 48 h reperfusion, the blood and kidneys were harvested for analysis. In vitro, Tisp40 overexpression and vector cells were subjected to hypoxia/reoxygenation (HR), the apoptosis rate and the expressions of related proteins were measured. Following IR, the expressions of Tisp40 protein, serum creatinine (sCr), blood urea nitrogen (BUN) and apoptosis of tubular cells were significantly increased in WT mice. However, Tisp40 deficiency significantly attenuated the increase of sCr, BUN and apoptosis of tubular cells. Following HR, apoptosis of tubular cells was increased in Tisp40 overexpression cells compared with vector cells. Mechanistically, Tisp40 promoted the expressions of C/EBP homologous protein (CHOP), Bax and Cleaved caspase3 and suppressed the expression of Bcl-2 in renal IR injury. In conclusion, Tisp40 aggravates tubular cells apoptosis in renal IR injury. - Highlights: • Tisp40 is induced in renal ischemia reperfusion. • Tisp40 knockout attenuates renal dysfunctions and tubular cell apoptosis. • Tisp40 overexpression increases tubular cell apoptosis in hypoxia/reoxygenation. • Tisp40 promotes CHOP mediated cell apoptosis in renal ischemia reperfusion.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Indomethacin induced glioma apoptosis involving ceramide signals

Highlights: • Indomethacin induced glioma cell apoptosis. • Indomethacin increased intracellular ceramide levels. • Ceramide induced glioma cell apoptosis. • LY294002 induced glioma cell apoptosis. • Ceramide/PP2A/Akt/Mcl-1, FLIP axis involved in indomethacin-induced apoptosis. Nonsteroidal anti-inflammatory drugs (NSAIDs) are increasingly implicated in the prevention and treatment of cancers apart from their known inhibitory effects on eicosanoid production. One of the NSAIDs, indomethacin, in particular shows promising antineoplastic outcome against glioma. To extend such finding, we here studied in human H4 and U87 glioma cells the possible involvement of the ceramide/protein phosphatase 2 A (PP2A)/Akt axis in the indomethacin-induced apoptosis. We found that the induced apoptosis was accompanied by a series of biochemical events, including intracellular ceramide generation, PP2A activation, Akt dephosphorylation, Mcl-1 and FLICE inhibiting protein (FLIP) transcriptional downregulation, Bax mitochondrial distribution, and caspase 3 activation. Such events were also duplicated with a cell-permeable C2-ceramide and Akt inhibitor LY294002. Pharmacological inhibition of ceramide synthase by fumonisin B1 and PP2A by okadaic acid moderately attenuated indomethacin-induced Akt dephosphorylation along with the apoptosis. Results suggested that the ceramide/PP2A/Akt axis is involved in the apoptosis and a possible cyclooxygenase-independent target for indomethacin. Furthermore, apoptosis regulatory proteins such as Mcl-1 and FLIP are potential downstream effectors of this axis and their downregulation could turn on the apoptotic program.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Inhibition of SH2-domain-containing inositol 5-phosphatase (SHIP2) ameliorates palmitate induced-apoptosis through regulating Akt/FOXO1 pathway and ROS production in HepG2 cells

The serine–threonine kinase Akt regulates proliferation and survival by phosphorylating a network of protein substrates; however, the role of a negative regulator of the Akt pathway, the SH2-domain-containing inositol 5-phosphatase (SHIP2) in apoptosis of the hepatocytes, remains unknown. In the present study, we studied the molecular mechanisms linking SHIP2 expression to apoptosis using overexpression or suppression of SHIP2 gene in HepG2 cells exposed to palmitate (0.5 mM). Overexpression of the dominant negative mutant SHIP2 (SHIP2-DN) significantly reduced palmitate-induced apoptosis in HepG2 cells, as these cells had increased cell viability, decreased apoptotic cell death and reduced the activity of caspase-3, cytochrome c and poly (ADP-ribose) polymerase. Overexpression of the wild-type SHIP2 gene led to a massive apoptosis in HepG2 cells. The protection from palmitate-induced apoptosis by SHIP2 inhibition was accompanied by a decrease in the generation of reactive oxygen species (ROS). In addition, SHIP2 inhibition was accompanied by an increased Akt and FOXO-1 phosphorylation, whereas overexpression of the wild-type SHIP2 gene had the opposite effects. Taken together, these findings suggest that SHIP2 expression level is an important determinant of hepatic lipoapotosis and its inhibition can potentially be a target in treatment of hepatic lipoapoptosis in diabetic patients. - Highlights: • Lipoapoptosis is the major contributor to the development of NAFLD. • The PI3-K/Akt pathway regulates apoptosis in different cells. • The role of negative regulator of this pathway, SHIP2 in lipoapoptosis is unknown. • SHIP2 inhibition significantly reduces palmitate-induced apoptosis in HepG2 cells. • SHIP2 inhibition prevents palmitate induced-apoptosis by regulating Akt/FOXO1 pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

4SC-202 activates ASK1-dependent mitochondrial apoptosis pathway to inhibit hepatocellular carcinoma cells

The aim of the present study is to investigate the potential anti-hepatocellular carcinoma (HCC) cell activity by 4SC-202, a novel class I HDAC inhibitor (HDACi). The associated signaling mechanisms were also analyzed. We showed that 4SC-202 treatment induced potent cytotoxic and proliferation–inhibitory activities against established HCC cell lines (HepG2, HepB3, SMMC-7721) and patient-derived primary HCC cells. Further, adding 4SC-202 in HCC cells activated mitochondrial apoptosis pathway, which was evidenced by mitochondrial permeability transition pore (mPTP) opening, cytochrome C cytosol release and caspase-3/-9 activation. Inhibition of this apoptosis pathway, by caspase-3/-9 inhibitors, mPTP blockers, or by shRNA-mediated knockdown of cyclophilin-D (Cyp-D, a key component of mPTP), significantly attenuated 4SC-202-induced HCC cell death and apoptosis. Reversely, over-expression of Cyp-D enhanced 4SC-202's sensitivity in HCC cells. Further studies showed that 4SC-202 induced apoptosis signal-regulating kinase 1 (ASK1) activation, causing it translocation to mitochondria and physical association with Cyp-D. This mitochondrial ASK1-Cyp-D complexation appeared required for mediating 4SC-202-induced apoptosis activation. ASK1 stable knockdown by targeted-shRNAs largely inhibited 4SC-202-induced mPTP opening, cytochrome C release, and following HCC cell apoptotic death. Together, we suggest that 4SC-202 activates ASK1-dependent mitochondrial apoptosis pathway to potently inhibit human HCC cells. - Highlights: • 4SC-202 exerts potent anti-proliferative and cytotoxic activity against established/primary HCC cells. • SC-202-induced anti-HCC cell activity relies on caspase-dependent apoptosis activation. • 4SC-202 activates Cyp-D-dependent mitochondrial apoptosis pathway in HCC cells. • 4SC-202 activates ASK1 in HCC cells, causing it translocation to mitochondria. • Mitochondrial ASK1-Cyp-D complexation mediates 4SC-202's activity in HCC cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Tankyrase regulates apoptosis by activating JNK signaling in Drosophila

Highlights: • Ectopic expression of DTNKS induces wing and eye defects. • DTNKS positively regulates cell apoptosis. • DTNKS regulates apoptosis by controlling JNK signaling activity. Programmed cell death (PCD), or apoptosis, plays essential roles in various cellular and developmental processes, and dysregulation of apoptosis causes many diseases. Thus, regulation of apoptotic process is very important. Drosophila tankyrase (DTNKS) is an evolutionarily conserved protein with poly(ADP-ribose) polymerase activity. In mammalian cells, tankyrases (TNKSs) have been reported to regulate cell death. To determine whether DTNKS plays function in inducing apoptosis in in vivo development, we used Drosophila as a model system and generated transgenic flies expressing DTNKS. We show that ectopic expression of DTNKS promotes caspase-dependent apoptosis and knockdown of DTNKS by RNAi dramatically alleviates apoptotic defect caused by ectopic expression of pro-apoptotic protein hid or rpr in the adult eye. Moreover, our result shows that ectopic expression of DTNKS triggers the activation of c-Jun N-terminal kinase (JNK) signaling, which is required for DTNKS-mediated apoptosis. Taken together, our finding identifies the role of DTNKS in regulating apoptosis by activating JNK signaling in Drosophila.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

LncRNA SNHG20 knockdown suppresses the osteosarcoma tumorigenesis through the mitochondrial apoptosis pathway by miR-139/RUNX2 axis

Highlights: • SNHG20 was up-regulated in osteosarcoma samples and its high-expression indicated the poor prognosis. • SNHG20 knockdown inhibited the proliferation, invasion and promoted the apoptosis of osteosarcoma cells in vitro. • SNHG20 knockdown up-regulated the expression levels of caspase-9, caspase-3 and Bax. • miR-139 both targeted with the 3′-UTR of RUNX2 and SNHG20. • SNHG20/miR-139/RUNX2 axis modulates the osteosarcoma tumorigenesis and apoptosis via mitochondrial apoptosis. Increasing evidence has indicated the important roles of long noncoding RNAs (lncRNAs) in human osteosarcoma tumorigenesis. In present study, we aim to investigate the roles of lncRNA SNHG20 (small nucleolar RNA host gene 20) in osteosarcoma tumorigenesis and explore the in-depth molecular mechanism. Results showed that lncRNA SNHG20 expression was up-regulated in osteosarcoma samples and its high-expression indicated the poor prognosis. Loss-of-functional experiments indicated that SNHG20 knockdown inhibited the proliferation, invasion and induced the apoptosis of osteosarcoma cells in vitro. Specifically, SNHG20 knockdown up-regulated the expression levels of caspase-9, caspase-3 and Bax, indicating that SNHG20 knockdown accelerated the apoptosis of osteosarcoma cells via mitochondrial apoptosis pathway. Bioinformatics analysis revealed that miR-139 both targeted with the 3′-UTR of runt-related transcription factor 2 (RUNX2) and SNHG20, which was verified by luciferase reporter assay and RNA immunoprecipitation (RIP). In conclusion, our data reveals that lncRNA SNHG20/miR-139/RUNX2 axis modulates the osteosarcoma tumorigenesis and apoptosis via mitochondrial apoptosis pathway, providing a novel insight for the pathophysiological process.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Ghrelin protects against depleted uranium-induced apoptosis of MC3T3-E1 cells through oxidative stress-mediated p38-mitogen-activated protein kinase pathway

Depleted uranium (DU) mainly accumulates in the bone over the long term. Osteoblast cells are responsible for the formation of bone, and they are sensitive to DU damage. However, studies investigating methods of reducing DU damage in osteoblasts are rarely reported. Ghrelin is a stomach hormone that stimulates growth hormones released from the hypothalamic–pituitary axis, and it is believed to play an important physiological role in bone metabolism. This study evaluates the impact of ghrelin on DU-induced apoptosis of the osteoblast MC3T3-E1 and investigates its underlying mechanisms. The results show that ghrelin relieved the intracellular oxidative stress induced by DU, eliminated reactive oxygen species (ROS) and reduced lipid peroxidation by increasing intracellular GSH levels; in addition, ghrelin effectively suppressed apoptosis, enhanced mitochondrial membrane potential, and inhibited cytochrome c release and caspase-3 activation after DU exposure. Moreover, ghrelin significantly reduced the expression of DU-induced phosphorylated p38-mitogen-activated protein kinase (MAPK). A specific inhibitor (SB203580) or specific siRNA of p38-MAPK could significantly suppress DU-induced apoptosis and related signals, whereas ROS production was not affected. In addition, ghrelin receptor inhibition could reduce the anti-apoptosis effect of ghrelin on DU and reverse the effect of ghrelin on intracellular ROS and p38-MAPK after DU exposure. These results suggest that ghrelin can suppress DU-induced apoptosis of MC3T3-E1 cells, reduce DU-induced oxidative stress by interacting with its receptor, and inhibit downstream p38-MAPK activation, thereby suppressing the mitochondrial-dependent apoptosis pathway. - Highlights: • Ghrelin suppressed DU-induced apoptosis of MC3T3-E1 cells. • Ghrelin inhibited DU-induced oxidative stress and further p38-MAPK activation. • Ghrelin further suppressed mitochondrial-dependent apoptosis pathway. • The anti-oxidation effect of ghrelin was regulated through its receptor. • Ghrelin has the potential for use in drug therapies for DU poisoning.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

A microtubule inhibitor, ABT-751, induces autophagy and delays apoptosis in Huh-7 cells

The objective was to investigate the upstream mechanisms of apoptosis which were triggered by a novel anti-microtubule drug, ABT-751, in hepatocellular carcinoma-derived Huh-7 cells. Effects of ABT-751 were evaluated by immunocytochemistry, flow cytometric, alkaline comet, soft agar, immunoblotting, CytoID, green fluorescent protein-microtubule associated protein 1 light chain 3 beta detection, plasmid transfection, nuclear/cytosol fractionation, coimmunoprecipitation, quantitative reverse transcription-polymerase chain reaction, small-hairpin RNA interference and mitochondria/cytosol fractionation assays. Results showed that ABT-751 caused dysregulation of microtubule, collapse of mitochondrial membrane potential, generation of reactive oxygen species (ROS), DNA damage, G{sub 2}/M cell cycle arrest, inhibition of anchorage-independent cell growth and apoptosis in Huh-7 cells. ABT-751 also induced early autophagy via upregulation of nuclear TP53 and downregulation of the AKT serine/threonine kinase (AKT)/mechanistic target of rapamycin (MTOR) pathway. Through modulation of the expression levels of DNA damage checkpoint proteins and G{sub 2}/M cell cycle regulators, ABT-751 induced G{sub 2}/M cell cycle arrest. Subsequently, ABT-751 triggered apoptosis with marked downregulation of B-cell CLL/lymphoma 2, upregulation of mitochondrial BCL2 antagonist/killer 1 and BCL2 like 11 protein levels, and cleavages of caspase 8 (CASP8), CASP9, CASP3 and DNA fragmentation factor subunit alpha proteins. Suppression of ROS significantly decreased ABT-751-induced autophagic and apoptotic cells. Pharmacological inhibition of autophagy significantly increased the percentages of ABT-751-induced apoptotic cells. The autophagy induced by ABT-751 plays a protective role to postpone apoptosis by exerting adaptive responses following microtubule damage, ROS and/or impaired mitochondria. - Highlights: • An anti-microtubule agent, ABT-751, induces autophagy and apoptosis in Huh-7 cells. • ABT-751 induces early autophagy and delays apoptosis. • ABT-751 induces autophagy via modulations of nuclear TP53 and AKT/MTOR pathways. • ABT-751-induced apoptosis is ROS-, mitochondria- and caspase-dependent. • Inhibition of autophagy enhances ABT-751-induced apoptosis.

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