TIGAR knockdown enhanced the anticancer effect of aescin via regulating autophagy and apoptosis in colorectal cancer cells.

Our previous study showed that TP53-induced glycolysis and apoptosis regulator (TIGAR) regulated ROS, autophagy, and apoptosis in response to hypoxia and chemotherapeutic drugs. Aescin, a triterpene saponin, exerts anticancer effects and increases ROS levels. The ROS is a key upstream signaling to activate autophagy. Whether there is a crosstalk between TIGAR and aescin in regulating ROS, autophagy, and apoptosis is unknown. In this study, we found that aescin inhibited cell viability and colony formation, and induced DNA damage, cell cycle arrest, and apoptosis in cancer cell lines HCT-116 and HCT-8 cells. Concurrently, aescin increased the expression of TIGAR, ROS levels, and autophagy activation. Knockdown of TIGAR enhanced the anticancer effects of aescin in vitro and in vivo, whereas overexpression of TIGAR or replenishing TIGAR downstream products, NADPH and ribose, attenuated aescin-induced apoptosis. Furthermore, aescin-induced ROS elevation and autophagy activation were further strengthened by TIGAR knockdown in HCT-116 cells. However, autophagy inhibition by knockdown of autophagy-related gene ATG5 or 3-methyladenine (3-MA) exaggerated aescin-induced apoptosis when TIGAR was knocked down. In conclusion, TIGAR plays a dual role in determining cancer cell fate via inhibiting both apoptosis and autophagy in response to aescin, which indicated that inhibition of TIGAR and/or autophagy may be a junctional therapeutic target in treatment of cancers with aescin.

Rottlerin upregulates DDX3 expression in hepatocellular carcinoma.

Rottlerin has been reported to exert its anti-tumor activity in various types of human cancers. However, the underlying molecular mechanism has not been fully elucidated. In the current study, we explored whether rottlerin exhibits its tumor suppressive function in hepatocellular carcinoma cells. Our MTT assay results showed that rottlerin inhibited cell growth in hepatocellular carcinoma cells. Moreover, we found that rottlerin induced cell apoptosis and caused cell cycle arrest at G1 phase. Furthermore, our wound healing assay result demonstrated that rottlerin retarded cell migration in hepatocellular carcinoma cells. Additionally, rottlerin suppressed cell migration and invasion. Notably, we found that rottlerin upregulated DDX3 expression and subsequently downregulated Cyclin D1 expression and increased p21 level. Importantly, down-regulation of DDX3 abrogated the rottlerin-mediated tumor suppressive function, whereas overexpression of DDX3 promoted the anti-tumor activity of rottlerin. Our study suggests that rottlerin exhibits its anti-cancer activity partly due to upregulation of DDX3 in hepatocellular carcinoma cells.

Escin-induced DNA damage promotes escin-induced apoptosis in human colorectal cancer cells via p62 regulation of the ATM/γH2AX pathway.

Escin, a triterpene saponin isolated from horse chestnut seed, has been used to treat encephaledema, tissue swelling and chronic venous insufficiency. Recent studies show that escin induces cell cycle arrest, tumor proliferation inhibition and tumor cell apoptosis. But the relationship between escin-induced DNA damage and cell apoptosis in tumor cells remains unclear. In this study, we investigated whether and how escin-induced DNA damage contributed to escin-induced apoptosis in human colorectal cancer cells. Escin (5-80 µg/mL) dose-dependently inhibited the cell viability and colony formation in HCT116 and HCT8 cells. Escin treatment induced DNA damage, leading to p-ATM and γH2AX upregulation. Meanwhile, escin treatment increased the expression of p62, an adaptor protein, which played a crucial role in controlling cell survival and tumorigenesis, and had a protective effect against escin-induced DNA damage: knockdown of p62 apparently enhanced escin-induced DNA damage, whereas overexpression of p62 reduced escin-induced DNA damage. In addition, escin treatment induced concentration- and time-dependent apoptosis. Similarly, knockdown of p62 significantly increased escin-induced apoptosis in vitro and produced en escin-like antitumor effect in vivo. Overexpression of p62 decreased the rate of apoptosis. Further studies revealed that the functions of p62 in escin-induced DNA damage were associated with escin-induced apoptosis, and p62 knockdown combined with the ATM inhibitor KU55933 augmented escin-induced DNA damage and further increased escin-induced apoptosis. In conclusion, our results demonstrate that p62 regulates ATM/γH2AX pathway-mediated escin-induced DNA damage and apoptosis.

Aescin-induced reactive oxygen species play a pro-survival role in human cancer cells via ATM/AMPK/ULK1-mediated autophagy.

Aescin, a natural mixture of triterpene saponins, has been reported to exert anticancer effect. Recent studies show that aescin increases intracellular reactive oxygen species (ROS) levels. However, whether the increased ROS play a role in the anticancer action of aescin remains to be explored. In this study, we demonstrated that aescin (20-80 µg/mL) dose-dependently induced apoptosis and activated mammalian target of rapamycin (mTOR)-independent autophagy in human hepatocellular carcinoma HepG2 cells and colon carcinoma HCT 116 cells. The activation of autophagy favored cancer cell survival in response to aescin, as suppression of autophagy with ATG5 siRNAs or 3-methyladenine (3-MA), a selective inhibitor of autophagy, promoted aescin-induced apoptosis in vitro, and significantly enhanced the anticancer effect of aescin in vivo. Meanwhile, aescin dose-dependently elevated intracellular ROS levels and activated Ataxia-telangiectasia mutated kinase/AMP-activated protein kinase/UNC-51-like kinase-1 (ATM/AMPK/ULK1) pathway. The ROS and ATM/AMPK/ULK1 pathway were upstream modulators of the aescin-induced autophagy, as N-acetyl-L-cysteine (NAC) or ATM kinase inhibitor (KU-55933) remarkably suppressed aescin-induced autophagy and consequently promoted aescin-induced apoptosis, whereas overexpression of ATG5 partly attenuated NAC-induced enhancement in aescin-induced apoptosis. In conclusion, this study provides new insights into the roles of aescin-mediated oxidative stress and autophagy in cancer cell survival. Our results suggest that combined administration of the antioxidants or autophagic inhibitors with aescin might be a potential strategy to enhance the anticancer effect of aescin.

RNAi-based functional analysis of bursicon genes related to wing expansion in gypsy moths.

Bursicon is a heterodimeric neuropeptide composed of Burs-α and Burs-ß subunits that plays an important role in cuticle tanning and wing expansion in insects. In this study, full-length cDNAs of Burs-α (LdBurs-α) and Burs-ß (LdBurs-ß) genes were identified in gypsy moth (Lymantria dispar) and cloned. The 480 bp and 420 bp open reading frames (ORFs) encode 159 and 129 amino acid polypeptides, respectively. LdBurs-α and LdBurs-ß have 11 conserved cysteine residues, and LdBurs-α and LdBurs-ß genes were expressed during all developmental stages according to quantitative reverse transcription PCR (qRT-PCR), with highest expression in the egg stage. High expression levels were also detected in the haemolymph, cuticle and head. To explore the physiological functions of LdBurs-α and LdBurs-ß, the genes were knocked down in larvae and pupae using RNA interference (RNAi), and expression levels of LdBurs-α and LdBurs-ß were decreased by 42.26-80.09%. Wing defects were observed in L. dispar pupae following Ldbursion silencing, with a phenotypic percentage ranging from 10.17% to 15.00%. RNAi-mediated knockdown of Ldbursicon prevented the expansion of male and female L. dispar adult wings, with malformation rates ranging from 6.38% and 30.00% to 57.69% and 69.23%, but no cuticle tanning defects were observed in pupae or adults. The results indicate that bursicon plays a key role in wing expansion in L. dispar adults, making it a potentially novel molecular target for insecticide-based control of this pest species.

Progressive Failure Analysis of Laminates with Embedded Wrinkle Defects Based on an Elastoplastic Damage Model.

Out-of-plane wrinkling has a significant influence on the mechanical performance of composite laminates. Numerical simulations were conducted to investigate the progressive failure behavior of fiber-reinforced composite laminates with out-of-plane wrinkle defects subjected to axial compression. To describe the material degradation, a three-dimensional elastoplastic damage model with four damage modes (i.e., fiber tensile failure, matrix failure, fiber kinking/splitting, and delamination) was developed based on the LaRC05 criterion. To improve the computational efficiency in searching for the fracture angle in the matrix failure analysis, a high-efficiency and robust modified algorithm that combines the golden section search method with an inverse interpolation based on an existing study is proposed. The elastoplastic damage model was implemented in the finite-element code Abaqus using a user-defined material subroutine in Abaqus/Explicit. The model was applied to the progressive failure analysis of IM7/8552 composite laminates with out-of-plane wrinkles subjected to axial compressive loading. The numerical results showed that the compressive strength prediction obtained by the elastoplastic damage model is more accurate than that derived with an elastic damage model. The present model can describe the nonlinearity of the laminate during the damage evolution and determine the correct damage locations, which are in good agreement with experimental observations. Furthermore, it was discovered that the plasticity effects should not be neglected in laminates with low wrinkle levels.

Dexamethasone-sparing regimen is an effective and safe alternative in overall antiemetic protection: A systematic review and meta-analysis.

OBJECTIVE: We performed a meta-analyisis to evaluate the efficacy of maintenance dexamethasone against acute or delayed chemotherapy-induced nausea and vomiting (CINV) in patients receiving moderately or highly emetic risk chemotherapy regimen. METHODS: PubMed, Embase, and Cochrane Library were searched for eligible studies. Data comparing maintenance dexamethasone with single-dose dexamethasone during the acute, delayed, and overall phase of CINV were extracted. Overall risk ratio (RR) was used to estimate the efficacy and adverse effects. RESULTS: Nine studies were included. In delayed phase, maintenance dexamethasone has similar efficacy to single-dose dexamethasone for no emetic episodes (RR, 1.06; 95% confidence interval [CI], 1.00-1.14), complete response (RR, 1.04; 95% CI, 0.98-1.11), complete control (RR, 1.07; 95% CI, 0.98-1.16), and total control (RR, 1.06; 95% CI, 0.91-1.23). In overall phase, maintenance dexamethasone has similar efficacy to single-dose dexamethasone for no emetic episodes (RR, 1.02; 95% CI, 0.94-1.11), complete response (RR, 1.02; 95% CI, 0.95 -1.09), complete control (RR, 1.03; 95% CI, 0.94-1.13), total control (RR, 1.05; 95% CI, 0.90-1.23), and no rescue medication (RR, 1.07; 95% CI, 0.97-1.19). Maintenance dexamethasone was only superior to single-dose dexamethasone for no rescue medication during delayed phase (RR, 1.10; 95% CI, 1.01-1.21, P = .034). The incidence of hiccup was observed higher in maintenance dexamethasone group (RR = 3.16, 95% CI, 1.12-8.92). CONCLUSION: The single-dose dexamethasone regimen offers high and similar overall control of symptoms as the maintenance dexamethasone regimen in this population. Multiple-day dexamethasone was suitable for patients who used rescue medication during the delayed phase.

Hybrid Approaches for Complex Parastomal Hernia Repair.

Parastomal hernia is one of the major complications of colostomy with high occurrence. From October 2011 to November 2014, a retrospective study was conducted by analyzing and following up data of 16 patients suffering from parastomal hernia who underwent a hybrid technique repair. The safety and efficacy of the hybrid technique for parastomal hernia repair was investigated in terms of complications. All cases were operated successfully and had no major immediate postoperative complications other than mild abdominal pain in 5 cases. No long-term postoperative complications were reported in the follow-up. The authors found hybrid technique to be safe and effective for parastomal hernia repair with fewer complications.

TIGAR regulates DNA damage and repair through pentosephosphate pathway and Cdk5-ATM pathway.

Previous study revealed that the protective effect of TIGAR in cell survival is mediated through the increase in PPP (pentose phosphate pathway) flux. However, it remains unexplored if TIGAR plays an important role in DNA damage and repair. This study investigated the role of TIGAR in DNA damage response (DDR) induced by genotoxic drugs and hypoxia in tumor cells. Results showed that TIGAR was increased and relocated to the nucleus after epirubicin or hypoxia treatment in cancer cells. Knockdown of TIGAR exacerbated DNA damage and the effects were partly reversed by the supplementation of PPP products NADPH, ribose, or the ROS scavenger NAC. Further studies with pharmacological and genetic approaches revealed that TIGAR regulated the phosphorylation of ATM, a key protein in DDR, through Cdk5. The Cdk5-AMT signal pathway involved in regulation of DDR by TIGAR defines a new role of TIGAR in cancer cell survival and it suggests that TIGAR may be a therapeutic target for cancers.

TIGAR has a dual role in cancer cell survival through regulating apoptosis and autophagy.

The p53-induced glycolysis and apoptosis regulator (TIGAR) inhibits glycolysis, resulting in higher intracellular NADPH, lower reactive oxygen species (ROS) and autophagy activity. In this study, we investigated whether TIGAR might exert dual impacts on cancer cell survival based on its ability to inhibit both apoptosis and autophagy. In liver or lung cancer cells treated with the anticancer drug epirubicin, TIGAR levels increased in a dose- and time-dependent manner. TIGAR silencing enhanced epirubicin-induced elevations in ROS levels and apoptosis rates, in a manner that was blocked by ectopic addition of NADPH or N-acetyl cysteine. These findings were correlated with reduced tumorigenicity and increased chemosensitivity in mouse xenograft tumor assays. In parallel, TIGAR silencing also enhanced the epirubicin-induced activation of autophagy, in a manner that was also blocked by ectopic addition of NADPH. Notably, TIGAR silencing also licensed epirubicin-mediated inactivation of the mTOR pathway, suggesting TIGAR also exerted a negative impact on autophagy. However, genetic or pharmacologic inhibition of autophagy increased epirubicin-induced apoptosis in TIGAR-silenced cells. Overall, our results revealed that TIGAR inhibits both apoptosis and autophagy, resulting in a dual impact on tumor cell survival in response to tumor chemotherapy. Cancer Res; 74(18); 5127-38. ©2014 AACR.

Inhibition of proliferation of estrogen receptor­positive MCF­7 human breast cancer cells by tamoxifen through c­Jun transcription factors.

Activator of protein 1 (AP-1) is a heterodimeric transcription factor composed of various members of the Jun and Fos families and binds to DNA at specific AP-1 binding sites. AP-1 transcriptional activity is increased by phosphorylation at serine residues in the c­Jun component of AP-1. In the present study, the proliferation of MCF-7 breast cancer cells was found to be suppressed by tamoxifen (TAM)-activated c-Jun through the protein kinase C (PKC) pathway. The molecular mechanism by which c­Jun activation induces antiproliferative signals in estrogen receptor (ER)-positive MCF-7 human breast cancer cells remains unknown. TAM inhibited the proliferation of ER-positive MCF-7 human breast cancer cells and ER-negative MDA-MB-435 human breast cancer cells and 48 h incubation with 10 µM TAM led to inhibition of 80% of proliferation. In addition, no significant difference in c-Jun mRNA and protein levels was detected in MCF-7 and MDA-MB-435 cells stimulated by TAM for 48 h. TAM treatment of MCF-7 cells activated the transcriptional activity of AP-1, which responds specifically to phorbol ester. To determine the role of c-Jun in the antiproliferation of MCF-7 cells stimulated by TAM, the inhibition rates of MCF­7 cells were correlated with c­Jun expression and stimulation of TAM. Results showed that the inhibition rate of TAM-stimulated MCF-7 cells was positively regulated by overexpression of c-Jun and negatively regulated by underexpression of c-Jun. Overall, these results indicate that the TAM-stimulated antiproliferation of MCF-7 cells is positively regulated by c-Jun through activation of the PKC pathway.