Phloroglucinol derivative MCPP induces cell apoptosis in human colon cancer

Hyaluronan-based nano-formulation with mesoporous silica enhances the anticancer efficacy of phloroglucinol against gastrointestinal cancers

Gastrointestinal cancers are one among the most frequently reported cancers where colorectal and gastric cancers ranks third leading cause of cancer related death worldwide. Phloroglucinol, a well-known therapeutic agent for cancer, where its usage has been limited due to its poor water solubility and bioavailability. Hence, our study aims to synthesize and characterize Hyaluronan grafted phloroglucinol loaded Mesoporous silica nanoparticles (MSN-PG-HA). Our nano-formulation hasn't shown any teratogenic effect on Zebrafish embryos, no hemolysis and toxic effect with normal fibroblast cells with a maximum concentration of 300 μg/mL. The cumulative drug release profile of MSN-PG-HA showed a maximum drug release of 96.9 % with 5 mM GSH under redox responsive drug release, which is crucial for targeting cancer cells. In addition, the MSN-PG-HA nanoparticles showed significant a cytotoxic effect against HCT-116, AGS and SW-620 with IC50 values of 86.5 μg/mL, 80.65 μg/mL and 109.255 μg/mL respectively. Also, the cellular uptake assay has shown an increased uptake of FITC-labeled-MSN-PG-HA by HA-receptor mediated endocytosis than FITC-labeled-MSN-PG without HA modification in CD44+ gastrointestinal cancer cell lines. The ability of MSN-PG-HA to target CD44+ cells was further exploited for its application in cancer stem cell research utilizing in silico analysis with various stem cell pathway related targets, in which PG showed higher binding affinity with Gli 1 and the simulation studies proving its effectiveness in disrupting the protein structure. Thus, the findings of our study with nano-formulation are safe and non-toxic to recommend for targeted drug delivery against gastrointestinal cancers as well as its affinity towards cancer stem cell pathway related proteins proving to be a significant formulation for cancer stem cell research.

Isobavachalcone Induces ROS-Mediated Apoptosis via Targeting Thioredoxin Reductase 1 in Human Prostate Cancer PC-3 Cells

Prostate carcinoma causes a great number of deaths every year; therefore, there is an urgent need to find new drug candidates to treat advanced prostate cancer. Isobavachalcone (IBC) is the chalcone composition of Psoralea corylifolia Linn used in traditional Chinese medicine. Although IBC demonstrates potent anticancer efficacy in numerous types of human cancer cells, the cellular targets of IBC have not been fully defined. In our study, we found that IBC may induce reactive oxygen species- (ROS-) mediated apoptosis via interaction with a selenocysteine (Sec) containing the antioxidant enzyme thioredoxin reductase 1 (TrxR1), and induce lethal endoplasmic reticulum (ER) stress by inhibiting TrxR1 activity and increasing ROS levels in human prostate cancer PC-3 cells. Furthermore, we also observed that knocking down TrxR1 would sensitized cancer cells to IBC treatment. Our study provides evidence for the anticancer mechanism of IBC with TrxR1 as a potential target.

Drug resistance in glioblastoma and cytotoxicity of seaweed compounds, alone and in combination with anticancer drugs: A mini review

BACKGROUND

Glioblastomas (GBM) are one of the most aggressive tumor of the central nervous system with an average life expectancy of only 1-2 years after diagnosis, even with the use of advanced treatments with surgery, radiation, and chemotherapy. There are several anticancer drugs with alkylating properties that have been used in the therapy of malignant gliomas. Temozolomide (TMZ) is one of them, widely used even in combination with ionizing radiation. However, the main disadvantage of using these types of drugs in the treatment of GBM is the development of cancer drug resistance. Research of bioactive compounds with anticancer activity has been heavily explored.

PURPOSE

This review focuses on a carotenoid and a phlorotannin present in seaweed, namely fucoxanthin and phloroglucinol, and their anticancer activity against glioblastoma. The combination of natural compounds with conventional drugs is also discussed.

CONCLUSION

Several natural compounds existing in seaweeds, such as fucoxanthin and phoroglucinol, have shown cytotoxic activity in models in vitro and in vivo, acting through different molecular mechanisms, such as antioxidant, antiproliferative, DNA damage/DNA repair, proapoptotic, antiangiogenic and antimetastic. Within the scope of interactions with conventional drugs, there are evidences that some seaweed compounds could be used to potentiate the action of anticancer drugs. However, their effects and mechanisms of action, alone or in combination with anticancer drugs, namely TMZ, in glioblastoma cell, still few explored and require more attention due to the unquestionable high potential of these marine compounds.

Differential Characterization of Temozolomide-Resistant Human Glioma Cells

Glioblastoma multiforme (GBM) is the most common type of primary and malignant tumor occurring in the adult central nervous system. Temozolomide (TMZ) has been considered to be one of the most effective chemotherapeutic agents to prolong the survival of patients with glioblastoma. Many glioma cells develop drug-resistance against TMZ that is mediated by increasing O-6-methylguanine-DNA methyltransferase (MGMT) levels. The expression of connexin 43 was increased in the resistant U251 subline compared with the parental U251 cells. The expression of epithelial-mesenchymal transition (EMT)-associated regulators, including vimentin, N-cadherin, and β-catenin, was reduced in the resistant U251 subline. In addition, the resistant U251 subline exhibited decreased cell migratory activity and monocyte adhesion ability compared to the parental U251 cells. Furthermore, the resistant U251 subline also expressed lower levels of vascular cell adhesion molecule (VCAM)-1 after treatment with recombinant tumor necrosis factor (TNF)-α. These findings suggest differential characteristics in the drug-resistant GBM from the parental glioma cells.

Enhancement of hyperthermia-induced apoptosis by 5Z-7-oxozeaenol, a TAK1 inhibitor, in Molt-4 cells

PURPOSE

Transforming growth factor-β-activated kinase1 (TAK1) plays an anti-apoptotic role in response to multiple stresses. TAK1 inhibitor, 5Z-7-oxozeaenol (OZ) has been studied for its apoptotic effects. However, the combined effect of OZ with physical stresses remains to be elusive. Therefore, in this study we focussed to determine the combined effects of OZ with hyperthermia (HT) using Molt-4 cell line.

MATERIALS AND METHODS

Molt-4 cells were pre-treated with OZ for 1 h followed by heat exposure (44 °C, 10 min) and harvested 24 h after incubation at 37 °C, apoptosis was measured by Annexin V-FITC/PI double staining assay using flow cytometry and cell growth was observed by cell counting assay. Further mechanism involved in the combination was investigated by measuring mitochondrial membrane potential (MMP), intracellular ROS generation, expression of apoptosis related protein, intracellular calcium ion level and Fas activity.

RESULTS

Combination of OZ with HT significantly enhances MMP loss and superoxide generation. Furthermore, OZ pre-treatment promotes caspase-8 cleavage, Fas externalisation, caspase 3 activity and intracellular calcium ion levels. OZ pre-treatment decreased the expression of HT-induced Bcl-2 and increased the expression of pro-apoptotic Bax, while markedly suppressed the phosphorylation of JNK and p38. In addition, increased expression of CHOP following combined treatment indicates that ER stress may also involve in the enhancement of HT-induced apoptosis.

CONCLUSION

Our data showed for the first time that OZ sensitizes Molt-4 cells to HT-induced apoptosis via extrinsic and intrinsic apoptotic pathways. Furthermore, ROS and ER stress may also play role in the enhancement of HT-induced apoptosis by OZ.

Tris (1,3-dichloro-2-propyl) phosphate-induced apoptotic signaling pathways in SH-SY5Y neuroblastoma cells

Tris (1, 3-dichloro-2-propyl) phosphate (TDCIPP, also known as TDCPP), an extensively used flame retardant, is frequently detected in the environment and biota. Recent studies have shown that TDCIPP has neurotoxic effects. In this study, we determined the mechanisms of TDCIPP-induced neurotoxicity in human neuroblastoma (SH-SY5Y) cells. By using morphological examination, flow cytometry, and mitochondrial membrane potential (ΔYm) measurement, we confirmed that exposure to TDCIPP caused apoptosis accompanied by the activation of apoptosis-related genes (e.g. Bax and Bcl-2) and caspase 3 protein in SH-SY5Y cells. Increased reactive oxygen species (ROS) formation and intracellular calcium ions ([Ca²⁺]_i) were also observed in TDCIPP-treated SH-SY5Y cells. Exposure to TDCIPP led to the activation of protein markers of endoplasmic reticulum (ER) stress, including eukaryotic translation initiation factor 2a subunit (p-EIF2a), activation transcription factor (ATF4), glucose-regulated protein (GRP78), and the proapoptotic factor C/EBP homologous protein (CHOP). To determine the role of the ER in apoptosis, phenyl butyric acid (PBA), an ER stress inhibitor, was applied. Treatment with PBA effectively attenuated TDCIPP-induced ER stress and protected against apoptotic death in SH-SY5Y cells by inhibition of Bax expression and promotion of Bcl-2 expression. Furthermore, we found that pretreatment of the cells with the ROS scavenger N-acetyl cysteine (NAC) inhibited the ER stress response and prevented apoptosis. The combination of PBA and NAC pretreatment could further prevent TDCIPP induced ER-stress and apoptotic death compared with PBA or NAC pretreatment alone. Thus, in the present study, we demonstrated that TDCIPP induces cytotoxicity through a ROS-dependent mechanism involving ER stress and activation of mitochondrial apoptotic pathways in SH-SY5Y cells.

A novel curcuminoid exhibits enhanced antitumor activity in nasopharyngeal carcinoma

Curcumin shows growth-inhibition against tumor cells through multi-target mechanisms. Nevertheless, the poor stability and pharmacokinetics considerably limit its clinical functions. Increased effort has been put into the chemical alteration of curcumin to find potential analogues with improved bioavailability and antitumor activities. In this study, the antitumor activity of a novel curcuminoid (B63) in nasopharyngeal carcinoma (NPC) was examined. The MTT and colony formation assays were used to detect NPC cell viability and proliferation. Flow cytometry was used to detect cell cycle distribution. The Annexin V/PI staining assay and cleavage PARP and cleavage caspase-3 expression were used to examine apoptosis. Western blotting was used to examine the protein expression of endoplasmic reticulum (ER) stress pathway markers, XBP-1, ATF-4 and CHOP. The suppressive effect of B63 on tumor growth was examined in vivo by subcutaneously inoculated NPC in a tumor model using nude mice. Treatment with B63 potentially caused growth inhibition and apoptosis in NPC cells in a dose- and time-responsive manner. Its antitumor effect was associated with the ER stress activation. Nevertheless, the same dose of curcumin did not activate ER stress. In addition, knockdown of Chop attenuated B63-induced cell viability inhibition, suggesting that the apoptotic pathway is ER stress-dependent. The tumor volume and weight were significantly reduced by pretreating the NPC cells with B63 before implantation in the in vivo mouse model. B63 exhibited a more potent antitumor action than curcumin in NPC. These observations on the novel compound B63 indicate a novel candidate for NPC therapy.

Association of CD44 Gene Polymorphism with Survival of NSCLC and Risk of Bone Metastasis

Background

Previous studies have reported CD44 expression influenced the development and progression of tumors. The aim of this study was to investigate whether single-nucleotide polymorphisms (SNPs) of the CD44 gene are associated with survival of non-small cell lung cancer (NSCLC) and occurrence rate of bone metastasis.

Material/Methods

A total of 234 patients with NSCLC between 2003 and 2010 were enrolled in this study and 468 healthy persons were used as controls. Two polymorphisms, rs13347 and rs187115, in the CD44 gene were genotyped using DNA from blood lymphocytes. For statistical analysis we used the chi-square test, Fisher’s exact test, Kaplan-Meier method, and log-rank test.

Results

CD44 gene rs13347 polymorphism was not associated with NSCLC risk. For rs187115, the association with NSCLC risk was observed (P<0.001). Allele G carriers had significantly higher occurrence rates of bone metastasis (OR=0.4, 95%CI: 0.20–0.64, P<0.001) and more advanced tumor stage (OR=2.6, 95%CI: 1.50–4.45, P=0.001) compared to carriers of allele A. The survival rates for patients with AA genotype were significantly higher than for patients with the AG+GG genotypes (P<0.001). In multivariate analysis of survival in NSCLC patients, significant predictors were CD44 gene (AG+GG) (RR=0.48, 95%CI: 0.34–0.68, P<0.001), tumor stage (RR=0.45, 95%CI: 0. 0.31–0.65, P<0.001), and bone metastasis (RR=1.52, 95%CI: 1.05–2.21, P=0.027).

Conclusions

CD44 gene rs187115 polymorphism is a potential predictive marker of survival in NSCLC patients, and is significantly correlated with bone metastasis and tumor stage.

Brain-derived neurotrophic factor regulates cell motility in human colon cancer

Brain-derived neurotrophic factor (BDNF) is a potent neurotrophic factor that has been shown to affect cancer cell metastasis and migration. In the present study, we investigated the mechanisms of BDNF-induced cell migration in colon cancer cells. The migratory activities of two colon cancer cell lines, HCT116 and SW480, were found to be increased in the presence of human BDNF. Heme oxygenase-1 (HO)-1 is known to be involved in the development and progression of tumors. However, the molecular mechanisms that underlie HO-1 in the regulation of colon cancer cell migration remain unclear. Expression of HO-1 protein and mRNA increased in response to BDNF stimulation. The BDNF-induced increase in cell migration was antagonized by a HO-1 inhibitor and HO-1 siRNA. Furthermore, the expression of vascular endothelial growth factor (VEGF) also increased in response to BDNF stimulation, as did VEGF mRNA expression and transcriptional activity. The increase in BDNF-induced cancer cell migration was antagonized by a VEGF-neutralizing antibody. Moreover, transfection with HO-1 siRNA effectively reduced the increased VEGF expression induced by BDNF. The BDNF-induced cell migration was regulated by the ERK, p38, and Akt signaling pathways. Furthermore, BDNF-increased HO-1 and VEGF promoter transcriptional activity were inhibited by ERK, p38, and AKT pharmacological inhibitors and dominant-negative mutants in colon cancer cells. These results indicate that BDNF increases the migration of colon cancer cells by regulating VEGF/HO-1 activation through the ERK, p38, and PI3K/Akt signaling pathways. The results of this study may provide a relevant contribution to our understanding of the molecular mechanisms by which BDNF promotes colon cancer cell motility.

Cantharidin Induces Apoptosis Through the Calcium/PKC-Regulated Endoplasmic Reticulum Stress Pathway in Human Bladder Cancer Cells

Bladder cancer is a common malignancy worldwide. However, there is still no effective therapy for bladder cancer. In this study, we investigated the cytotoxic effects of cantharidin [a natural toxin produced (pure compound) from Chinese blister beetles (Mylabrisphalerata or Mylabriscichorii) and Spanish flies (Cantharis vesicatoria)] in human bladder cancer cell lines (including: T24 and RT4 cells). Treatment of human bladder cancer cells with cantharidin significantly decreased cell viability. The increase in the expressions of caspase-3 activity and cleaved form of caspase-9/-7/-3 were also increased in cantharidin-treated T24 cells. Furthermore, cantharidin increased the levels of phospho-eIF2α and Grp78 and decreased the protein expression of procaspase-12, which was accompanied by the increase in calpain activity in T24 cells. Cantharidin was capable of increasing the intracellular Ca 2+ and the phosphorylation of protein kinase C (PKC) in T24 cells. The addition of BAPTA/AM (a Ca 2+ chelator) and RO320432 (a selective cell-permeable PKC inhibitor) effectively reversed the increase in caspase-3 and calpain activity, the phosphorylation levels of PKC and eIF2α and Grp78 protein expression, and the decrease in procaspase-12 expression induced by cantharidin. Importantly, cantharidin significantly decreased the tumor volume (a dramatic 71% reduction after 21 days of treatment) in nude mice xenografted with T24 cells. Taken together, these results indicate cantharidin induced human bladder cancer cell apoptosis through a calcium/PKC-regulated ER stress pathway. These findings suggest that cantharidin may be a novel and potential anticancer agent targeting on bladder cancer cells.

Effects of paeonol on anti-neuroinflammatory responses in microglial cells

Increasing studies suggest that inflammatory processes in the central nervous system mediated by microglial activation plays an important role in numerous neurodegenerative diseases. Development of planning for microglial suppression is considered a key strategy in the search for neuroprotection. Paeonol is a major phenolic component of Moutan Cortex, widely used as a nutrient supplement in Chinese medicine. In this study, we investigated the effects of paeonol on microglial cells stimulated by inflammagens. Paeonol significantly inhibited the release of nitric oxide (NO) and the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Treatment with paeonol also reduced reactive oxygen species (ROS) production and inhibited an ATP-induced increased cell migratory activity. Furthermore, the inhibitory effects of neuroinflammation by paeonol were found to be regulated by phosphorylated adenosine monophosphate-activated protein kinase-α (AMPK-α) and glycogen synthase kinase 3 α/β (GSK 3α/β). Treatment with AMPK or GSK3 inhibitors reverse the inhibitory effect of neuroinflammation by paeonol in microglial cells. Furthermore, paeonol treatment also showed significant improvement in the rotarod performance and microglial activation in the mouse model as well. The present study is the first to report a novel inhibitory role of paeonol on neuroinflammation, and presents a new candidate agent for the development of therapies for inflammation-related neurodegenerative diseases.

Calcium homeostasis and ER stress in control of autophagy in cancer cells

Autophagy is a basic catabolic process, serving as an internal engine during responses to various cellular stresses. As regards cancer, autophagy may play a tumor suppressive role by preserving cellular integrity during tumor development and by possible contribution to cell death. However, autophagy may also exert oncogenic effects by promoting tumor cell survival and preventing cell death, for example, upon anticancer treatment. The major factors influencing autophagy are Ca²⁺ homeostasis perturbation and starvation. Several Ca²⁺ channels like voltage-gated T- and L-type channels, IP3 receptors, or CRAC are involved in autophagy regulation. Glucose transporters, mainly from GLUT family, which are often upregulated in cancer, are also prominent targets for autophagy induction. Signals from both Ca²⁺ perturbations and glucose transport blockage might be integrated at UPR and ER stress activation. Molecular pathways such as IRE 1-JNK-Bcl-2, PERK-eIF2α-ATF4, or ATF6-XBP 1-ATG are related to autophagy induced through ER stress. Moreover ER molecular chaperones such as GRP78/BiP and transcription factors like CHOP participate in regulation of ER stress-mediated autophagy. Autophagy modulation might be promising in anticancer therapies; however, it is a context-dependent matter whether inhibition or activation of autophagy leads to tumor cell death.

Isofraxidin, a potent reactive oxygen species (ROS) scavenger, protects human leukemia cells from radiation-induced apoptosis via ROS/mitochondria pathway in p53-independent manner

Ionizing radiation (IR) leads to oxidizing events such as excessive reactive oxygen species (ROS) in the exposed cells, resulting in further oxidative damage to lipids, proteins and DNA. To screen the potential radio-protective drug, the intracellular ROS was measured in irradiated U937 cells pretreated with 80 candidate traditional herbal medicine, respectively. Isofraxidin (IF) was one possible radio-protector in these 80 drugs. This study investigated the radio-protective role of IF, a Coumarin compound, in human leukemia cell lines, for the first time. Results indicate that IF protects against IR-induced apoptosis in U937 cells in the time- and concentration- dependent manner. IF decreases IR-induced intracellular ROS generation, especially hydroxyl radicals formation, inhibits IR-induced mitochondrial membrane potential loss and reduces IR-induced high intracellular Ca(2+) levels regardless of ER stress. IF down-regulates the expression of caspase-3, phospho-JNK, phospho-p38 and activates Bax in mitochondria. IF inhibits cytochrome c release from mitochondria to cytosol. IF also moderates IR-induced Fas externalization and caspase-8 activation. IF also exhibits significant protection against IR-induced cell death in other leukemia cell lines such as Molt-4 cells and HL60 cells regardless of p53. Taken together, the data demonstrate that IF protects leukemia cells from radiation-induced apoptosis via ROS/mitochondria pathway in a p53-independent manner.

Chloroacetic acid triggers apoptosis in neuronal cells via a reactive oxygen species-induced endoplasmic reticulum stress signaling pathway

Chloroacetic acid (CA), a chlorinated analog of acetic acid and an environmental toxin that is more toxic than acetic, dichloroacetic, or trichloroacetic acids, is widely used in chemical industries. Furthermore, CA has been found to be the major disinfection by-products (DBPs) of drinking water. CA has been reported to be highly corrosive and to induce severe tissue injuries (including nervous system) that lead to death in mammals. However, the effects and underlying mechanisms of CA-induced neurotoxicity remain unknown. In the present study, we found that CA (0.5-2.0 mM) significantly increased LDH release, decreased the number of viable cells (cytotoxicity) and induced apoptotic events (including: increases in the numbers of apoptotic cells, the membrane externalization of phosphatidylserine (PS), and caspase-3/-7 activity) in Neuro-2a cells. CA (1.5 mM; the approximate to LD50) also triggered ER stress, which was identified by monitoring several key molecules that are involved in the unfolded protein responses (including the increase in the expressions of p-PERK, p-IRE-1, p-eIF2α, ATF-4, ATF-6, CHOP, XBP-1, GRP 78, GRP 94, and caspase-12) and calpain activity. Transfection of GRP 78- and GRP 94-specific si-RNA effectively abrogated CA-induced cytotoxicity, caspase-3/-7 and caspase-12 activity, and GRP 78 and GRP 94 expression in Neuro-2a cells. Additionally, pretreatment with 2.5 mM N-acetylcysteine (NAC; a glutathione (GSH) precursor) dramatically suppressed the increase in lipid peroxidation, cytotoxicity, apoptotic events, calpain and caspase-12 activity, and ER stress-related molecules in CA-exposed cells. Taken together, these results suggest that the higher concentration of CA exerts its cytotoxic effects in neuronal cells by triggering apoptosis via a ROS-induced ER stress signaling pathway.

Regulatory effects of fisetin on microglial activation

Increasing evidence suggests that inflammatory processes in the central nervous system that are mediated by microglial activation play a key role in neurodegeneration. Fisetin, a plant flavonol commonly found in fruits and vegetables, is frequently added to nutritional supplements due to its antioxidant properties. In the present study, treatment with fisetin inhibited microglial cell migration and ROS (reactive oxygen species) production. Treatment with fisetin also effectively inhibited LPS plus IFN-γ-induced nitric oxide (NO) production, and inducible nitric oxide synthase (iNOS) expression in microglial cells. Furthermore, fisetin also reduced expressions of iNOS and NO by stimulation of peptidoglycan, the major component of the Gram-positive bacterium cell wall. Fisetin also inhibited the enhancement of LPS/IFN-γ- or peptidoglycan-induced inflammatory mediator IL (interlukin)-1 β expression. Besides the antioxidative and anti-inflammatory effects of fisetin, our study also elucidates the manner in fisetin-induced an endogenous anti-oxidative enzyme HO (heme oxygenase)-1 expression. Moreover, the regulatory molecular mechanism of fisetin-induced HO-1 expression operates through the PI-3 kinase/AKT and p38 signaling pathways in microglia. Notably, fisetin also significantly attenuated inflammation-related microglial activation and coordination deficit in mice in vivo. These findings suggest that fisetin may be a candidate agent for the development of therapies for inflammation-related neurodegenerative diseases.

p53 is a key regulator for osthole-triggered cancer pathogenesis

Osthole has been reported to have antitumor activities via the induction of apoptosis and inhibition of cancer cell growth and metastasis. However, the detailed molecular mechanisms underlying the anticancer effects of osthole in human colon cancer remain unclear. In the present study, we have assessed osthole-induced cell death in two different human colon cancer cell lines, HCT116 and SW480. Our results also showed that osthole activated proapoptotic signaling pathways in human colon cancer cells. By using cell culture insert system, osthole reduced cell motility in both human colon cancer cell lines. This study also provides evidence supporting the potential of osthole in p53 activation. Expression of p53, an apoptotic protein, was remarkably upregulated in cells treated with osthole. Importantly, the levels of phosphorylation of p53 on Ser15 (p-p53) and acetylation of p53 on Lys379 (acetyl-p53) were increased under osthole treatment. Our results also demonstrated that p53 was activated followed by generation of reactive oxygen species (ROS) and activation of c-Jun N-terminal kinase (JNK). Our study provides novel insights of p53-mediated responses under osthole treatment. Taken together, we concluded that osthole induces cancer cell death and inhibits migratory activity in a controlled manner and is a promising candidate for antitumor drug development.

Glabridin mediate caspases activation and induces apoptosis through JNK1/2 and p38 MAPK pathway in human promyelocytic leukemia cells

Background

Glabridin, a prenylated isoflavonoid of G. glabra L. roots, has been associated with a wide range of biological properties such as regulation of energy metabolism, estrogenic, neuroprotective, anti-osteoporotic, and skin-whitening in previous studies. However, the effect of glabridin on tumor cells metastasis has not been clearly clarified. Here, the molecular mechanism by which glabridin anticancer effects in human promyelocytic leukemia cells was investigated.

Methodology and Principal Findings

The results showed that glabridin significantly inhibited cell proliferation of four AML cell lines (HL-60, MV4-11, U937, and THP-1). Furthermore, glabridin induced apoptosis of HL-60 cells through caspases-3, -8, and -9 activations and PARP cleavage in dose- and time-dependent manner. Moreover, western blot analysis also showed that glabridin increase phosphorylation of ERK1/2, p38 MAPK and JNK1/2 in dose- and time-dependent manner. Inhibition of p38 MAPK and JNK1/2 by specific inhibitors significantly abolished the glabridin-induced activation of the caspase-3, -8 and -9.

Conclusion

Taken together, our results suggest that glabridin induced HL-60 cell apoptosis through p38 MAPK and JNK1/2 pathways and could serve as a potential additional chemotherapeutic agent for treating AML.

Combination treatment of tamoxifen with risperidone in breast cancer

Tamoxifen has long been used and still is the most commonly used endocrine therapy for treatment of both early and advanced estrogen receptor-positive breast cancer in pre- and post-menopause women. Tamoxifen exerts its cytotoxic effect primarily through cytostasis which is associated with the accumulation of cells in the G0/G1 phase of the cell cycle. Apoptotic activity can also be exerted by tamoxifen which involves cleavage of caspase 9, caspase 7, caspase 3, and poly-ADP-ribose polymerase (PARP). Down-regulation of anti-apoptotic proteins Bcl-2 and Bcl-xL and up-regulation of pro-apoptotic proteins Bax and Bak have also been observed. In addition, stress response protein of GRP 94 and GRP 78 have also been induced by tamoxifen in our study. However, side effects occur during tamoxifen treatment in breast cancer patients. Researching into combination regimen of tamoxifen and drug(s) that relieves tamoxifen-induced hot flushes is important, because drug interactions may decrease tamoxifen efficacy. Risperidone has been shown to be effective in reducing or eliminating hot flushes on women with hormonal variations. In this present study, we demonstrated that combination of tamoxifen with risperidone did not interfered tamoxifen-induced cytotoxic effects in both in vitro and in vivo models, while fluoxetine abrogated the effects of tamoxifen. This is the first paper suggesting the possibility of combination treatment of tamoxifen with risperidone in breast cancer patients, providing a conceivable resolution of tamoxifen-induced side effects without interfering the efficacy of tamoxifen against breast cancer.

Exogenous endothelin-1 induces cell migration and matrix metalloproteinase expression in U251 human glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common and lethal type of primary brain tumor characterized by its rapid infiltration to surrounding tissues during the early stages. The fast spreading of GBM obscures the initiation of the tumor mass making the treatment outcome undesirable. Endothelin-1 is known as a secretory protein presented in various types of brain cells, which has been indicated as a factor for cancer pathology. The aim of the present study was to investigate the molecular mechanism of cell migration in GBM. We found that various malignant glioma cells expressed higher amounts of endothelin-1, ETA, and ETB receptors than nonmalignant human astrocytes. The application of endothelin-1 enhanced the migratory activity in human U251 glioma cells corresponding to increased expression of matrix metalloproteinase (MMP)-9 and MMP-13. The endothelin-1-induced cell migration was attenuated by MMP-9 and MMP-13 inhibitors and inhibitors of mitogen-activated protein (MAP) kinase and PI3 kinase/Akt. Furthermore, the elevated levels of phosphate c-Jun accumulation in the nucleus and activator protein-1 (AP-1)-DNA binding activity were also found in endothelin-1 treated glioma cells. In migration-prone sublines, cells with greater migration ability showed higher endothelin-1, ETB receptor, and MMP expressions. These results indicate that endothelin-1 activates MAP kinase and AP-1 signaling, resulting in enhanced MMP-9 and MMP-13 expressions and cell migration in GBM.

CD44 gene polymorphisms and environmental factors on oral cancer susceptibility in Taiwan

Background

Oral squamous cell carcinoma (OSCC) is the fourth leading cause of male cancer death in Taiwan. Exposure to environmental carcinogens is the primary risk factor for developing OSCC. CD44, a well-known tumor marker, plays a crucial role in tumor cell differentiation, invasion, and metastasis. This study investigated CD44 single-nucleotide polymorphisms (SNPs) with environmental risk factors to determine OSCC susceptibility and clinicopathological characteristics.

Methodology/Principal Findings

Real-time polymerase chain reaction (PCR) was used to analyze 6 SNPs of CD44 in 599 patients with oral cancer and 561 cancer-free controls. We determined that the CD44 rs187115 polymorphism carriers with the genotype AG, GG, or AG+GG were associated with oral cancer susceptibility. Among 731 smokers, CD44 polymorphisms carriers with the betel-nut chewing habit had a 10.30–37.63-fold greater risk of having oral cancer compared to CD44 wild-type (WT) carriers without the betel-nut chewing habit. Among 552 betel-nut chewers, CD44 polymorphisms carriers who smoked had a 4.23–16.11-fold greater risk of having oral cancer compared to those who carried the WT but did not smoke. Finally, we also observed that the stage III and IV oral cancer patients had higher frequencies of CD44 rs187115 polymorphisms with the variant genotype (AG+GG) compared with the wild-type (WT) carriers.

Conclusion

Our results suggest that gene–environment interactions between the CD44 polymorphisms and betel quid chewing and tobacco smoking increase the susceptibility to oral cancer development. Patients with CD44 rs187115 variant genotypes (AG+GG) were correlated with a higher risk of oral cancer development, and these patients may possess greater chemoresistance to advanced- to late-stage oral cancer than WT carriers do. The CD44 rs187115 polymorphism has potential predictive significance in oral carcinogenesis and also may be applied as factors to predict the clinical stage in OSCC patients.

Anti-neuroinflammatory effects of the calcium channel blocker nicardipine on microglial cells: implications for neuroprotection

BACKGROUND/OBJECTIVE

Nicardipine is a calcium channel blocker that has been widely used to control blood pressure in severe hypertension following events such as ischemic stroke, traumatic brain injury, and intracerebral hemorrhage. However, accumulating evidence suggests that inflammatory processes in the central nervous system that are mediated by microglial activation play important roles in neurodegeneration, and the effect of nicardipine on microglial activation remains unresolved.

METHODOLOGY/PRINCIPAL FINDINGS

In the present study, using murine BV-2 microglia, we demonstrated that nicardipine significantly inhibits microglia-related neuroinflammatory responses. Treatment with nicardipine inhibited microglial cell migration. Nicardipine also significantly inhibited LPS plus IFN-γ-induced release of nitric oxide (NO), and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Furthermore, nicardipine also inhibited microglial activation by peptidoglycan, the major component of the Gram-positive bacterium cell wall. Notably, nicardipine also showed significant anti-neuroinflammatory effects on microglial activation in mice in vivo.

CONCLUSION/SIGNIFICANCE

The present study is the first to report a novel inhibitory role of nicardipine on neuroinflammation and provides a new candidate agent for the development of therapies for inflammation-related neurodegenerative diseases.

Osthole suppresses the migratory ability of human glioblastoma multiforme cells via inhibition of focal adhesion kinase-mediated matrix metalloproteinase-13 expression

Glioblastoma multiforme (GBM) is the most common type of primary and malignant tumor occurring in the adult central nervous system. GBM often invades surrounding regions of the brain during its early stages, making successful treatment difficult. Osthole, an active constituent isolated from the dried C. monnieri fruit, has been shown to suppress tumor migration and invasion. However, the effects of osthole in human GBM are largely unknown. Focal adhesion kinase (FAK) is important for the metastasis of cancer cells. Results from this study show that osthole can not only induce cell death but also inhibit phosphorylation of FAK in human GBM cells. Results from this study show that incubating GBM cells with osthole reduces matrix metalloproteinase (MMP)-13 expression and cell motility, as assessed by cell transwell and wound healing assays. This study also provides evidence supporting the potential of osthole in reducing FAK activation, MMP-13 expression, and cell motility in human GBM cells.

GDNF increases cell motility in human colon cancer through VEGF-VEGFR1 interaction

Glial cell line-derived neurotrophic factor (GDNF), a potent neurotrophic factor, has been shown to affect cancer cell metastasis and invasion. However, the molecular mechanisms underlying GDNF-induced colon cancer cell migration remain unclear. GDNF is found to be positively correlated with malignancy in human colon cancer patients. The migratory activities of two human colon cancer cell lines, HCT116 and SW480, were found to be enhanced in the presence of human GDNF. The expression of vascular endothelial growth factor (VEGF) was also increased in response to GDNF stimulation, along with VEGF mRNA expression and transcriptional activity. The enhancement of GDNF-induced cancer cell migration was antagonized by a VEGF-neutralizing antibody. Our results also showed that the expression of VEGF receptor 1 (VEGFR1) was increased in response to GDNF stimulation, whereas GDNF-induced cancer cell migration was reduced by a VEGFR inhibitor. The GDNF-induced VEGF expression was regulated by the p38 and PI3K/Akt signaling pathways. Treatment with GDNF increased nuclear hypoxia-inducible factor 1 α (HIF1α) accumulation and its transcriptional activity in a time-dependent manner. Moreover, GDNF increased hypoxia responsive element (HRE)-containing VEGF promoter transcriptional activity but not that of the HRE-deletion VEGF promoter construct. Inhibition of HIF1α by a pharmacological inhibitor or dominant-negative mutant reduced the GDNF-induced migratory activity in human colon cancer cells. These results indicate that GDNF enhances the migration of colon cancer cells by increasing VEGF-VEGFR interaction, which is mainly regulated by the p38, PI3K/Akt, and HIF1α signaling pathways.

Unraveling the caspase-mediated mechanism for phloroglucinol-encapsulated starch biopolymer against the breast cancer cell line MDA-MB-231

The main objective of the study is to decipher the mechanism underlying the anticancer activity of phloroglucinol-encapsulated starch biopolymer against the breast cancer cell line MDA-MB-231.

The role of glycogen synthase kinase-3β in glioma cell apoptosis induced by remifentanil

The aim of malignant glioma treatment is to inhibit tumor cell proliferation and induce tumor cell apoptosis. Remifentanil is a clinical anesthetic drug that can activate the N-methyl-D-aspartate (NMDA) receptor. NMDA receptor signaling activates glycogen synthase kinase-3β (GSK-3β). Discovered some 32 years ago, GSK-3β was only recently considered as a therapeutic target in cancer treatment. The purpose of this study was to assess whether remifentanil can induce the apoptosis of C6 cells through GSK-3β activation. 3-(4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) was used to detect cell viability. Hoechst 33342 staining and flow cytometry were used to detect cell apoptosis. The effect of GSK-3β activation was detected using a GSK-3β activation assay kit and 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), a potent and selective small molecule inhibitor of GSK-3β. The MTT assay indicated that remifentanil induced C6 cell death in a concentration- and time-dependent manner. Hoechst 33342 staining and flow cytometry showed that remifentanil significantly induced C6 cell apoptosis. The measurement of GSK-3β activation showed that remifentanil increased the cellular level of GSK-3β. All of these toxic effects can be attenuated by treatment with TDZD-8. These results suggest that remifentanil is able to induce C6 cell apoptosis through GSK-3β activation, which provides a basis for its potential use in the treatment of malignant gliomas.

Arsenic induces reactive oxygen species-caused neuronal cell apoptosis through JNK/ERK-mediated mitochondria-dependent and GRP 78/CHOP-regulated pathways

Arsenic (As), a well-known high toxic metal, is an important environmental and industrial contaminant, and it induces oxidative stress, which causes many adverse health effects and diseases in humans, particularly in inorganic As (iAs) more harmful than organic As. Recently, epidemiological studies have suggested a possible relationship between iAs exposure and neurodegenerative disease development. However, the toxicological effects and underlying mechanisms of iAs-induced neuronal cell injuries are mostly unknown. The present study demonstrated that iAs significantly decreased cell viability and induced apoptosis in Neuro-2a cells. iAs also increased oxidative stress damage (production of malondialdehyde (MDA) and ROS, and reduction of Nrf2 and thioredoxin protein expression) and induced several features of mitochondria-dependent apoptotic signals, including: mitochondrial dysfunction, the activations of PARP and caspase cascades, and the increase in caspase-3 activity. Pretreatment with the antioxidant N-acetylcysteine (NAC) effectively reversed these iAs-induced responses. iAs also increased the phosphorylation of JNK and ERK1/2, but did not that p38-MAPK, in treated Neuro-2a cells. NAC and the specific JNK inhibitor (SP600125) and ERK1/2 inhibitor (PD98059) abrogated iAs-induced cell cytotoxicity, caspase-3/-7 activity, and JNK and ERK1/2 activation. Additionally, exposure of Neuro-2a cells to iAs triggered endoplasmic reticulum (ER) stress identified through several key molecules (GRP 78, CHOP, XBP-1, and caspase-12), which was prevented by NAC. Transfection with GRP 78- and CHOP-specific si-RNA dramatically suppressed GRP 78 and CHOP expression, respectively, and attenuated the activations of caspase-12, -7, and -3 in iAs-exposed cells. Therefore, these results indicate that iAs induces ROS causing neuronal cell death via both JNK/ERK-mediated mitochondria-dependent and GRP 78/CHOP-triggered apoptosis pathways.

Resistin protects against 6-hydroxydopamine-induced cell death in dopaminergic-like MES23.5 cells

Resistin is originally reported as an adipose tissue-specific hormone and is thought to represent a link between obesity and insulin-resistant diabetes. Adipokines exert energy-regulation and has been reported to have neuroprotective effect like leptin, adiponectin, and ghrelin. However, the role of resistin in neuroprotective effect has not been explored. 6-hydroxydopamine (6-OHDA), one of the most investigated Parkinson's disease neurotoxins, is widely used to study mechanisms of cell death in dopaminergic neurons. In the present study, our results show that treatment of resistin protects 6-OHDA-induced cell death in dopaminergic-like MES23.5 cells. Resistin also antagonizes 6-OHDA-induced apoptotic cell death measured by fluorescence-activated cell sorter (FACS) analysis and Hochest 33342 staining. Furthermore, treatment of resistin also dramatically reduces 6-OHDA-mediated ROS production and mitochondria transmembrane potential dissipation. Moreover, expression of 6-OHDA-induced apoptotic markers, such as Bcl-2 degradation, Bax expression, PARP degradation and caspase 3 activity increase, are all attenuated by resistin treatment. Our results also show that resistin induces up-regulation of heat shock protein (Hsp) 32 (heme oxygenase-1, HO-1) and Hsc (heat shock cognate) 70. The protective effect of resistin on 6-OHDA-induced cell death is abolished by HO-1 inhibitor zinc protoporphyrin IX and HSP inhibitor KNK437. These results suggest the neuroprotective effects of resistin against 6-OHDA-induced cell death with the underlying mechanisms of inhibiting oxidative stress and apoptosis. Therefore, we suggest that resistin may provide a useful therapeutic strategy for neurodegenerative diseases such as Parkinson's disease.

The novel phloroglucinol derivative BFP induces apoptosis of glioma cancer through reactive oxygen species and endoplasmic reticulum stress pathways

Prenyl-phloroglucinol derivatives from hop plants have been shown to have anticancer activities. This study is the first to investigate the anticancer effects of the new phloroglucinol derivative (2,4-bis(4-fluorophenylacetyl)phloroglucinol; BFP). BFP induced cell death and anti-proliferation in three glioma, U251, U87 and C6 cells, but not in primary human astrocytes. BFP-induced concentration-dependently cell death in glioma cells was determined by MTT and SRB assay. Moreover, BFP-induced apoptotic cell death in glioma cells was measured by Hochest 33258 staining and fluorescence-activated cell sorter (FACS) of propidine iodine (PI) analysis. Treatment of U251 human glioma cells with BFP was also found to induce reactive oxygen species (ROS) generation, which was detected by a fluorescence dye used FACS analysis. Treatment of BFP also increased a number of signature endoplasmic reticulum (ER) stress markers glucose-regulated protein (GRP)-78, GRP-94, IRE1, phosphorylation of eukaryotic initiation factor-2α (eIF-2α) and up-regulation of CAAT/enhancer-binding protein homologous protein (CHOP). Moreover, treatment of BFP also increased the down-stream caspase activation, such as pro-caspase-7 and pro-caspase-12 degradation, suggesting the induction of ER stress. Furthermore, BFP also induced caspase-9 and caspase-3 activation as well as up-regulation of cleaved PARP expression. Treatment of antioxidants, or pre-transfection of cells with GRP78 or CHOP siRNA reduced BFP-mediated apoptotic-related protein expression. Taken together, the present study provides evidences to support that ROS generation, GRP78 and CHOP activation are mediating the BFP-induced human glioma cell apoptosis.

Effect of rosemary polyphenols on human colon cancer cells: transcriptomic profiling and functional enrichment analysis

In this work, the effect of rosemary extracts rich on polyphenols obtained using pressurized fluids was investigated on the gene expression of human SW480 and HT29 colon cancer cells. The application of transcriptomic profiling and functional enrichment analysis was done via two computational approaches, Ingenuity Pathway Analysis and Gene Set Enrichment Analysis. These two approaches were used for functional enrichment analysis as a previous step for a reliable interpretation of the data obtained from microarray analysis. Reverse transcription quantitative-PCR was used to confirm relative changes in mRNA levels of selected genes from microarrays. The selection of genes was based on their expression change, adjusted p value, and known biological function. According to genome-wide transcriptomics analysis, rosemary polyphenols altered the expression of ~4 % of the genes covered by the Affymetrix Human Gene 1.0ST chip in both colon cancer cells. However, only ~18 % of the differentially expressed genes were common to both cell lines, indicating markedly different expression profiles in response to the treatment. Differences in induction of G2/M arrest observed by rosemary polyphenols in the two colon adenocarcinoma cell lines suggest that the extract may be differentially effective against tumors with specific mutational pattern. From our results, it is also concluded that rosemary polyphenols induced a low degree of apoptosis indicating that other multiple signaling pathways may contribute to colon cancer cell death.

Wogonin induces reactive oxygen species production and cell apoptosis in human glioma cancer cells

Glioma is the most common primary adult brain tumor with poor prognosis because of the ease of spreading tumor cells to other regions of the brain. Cell apoptosis is frequently targeted for developing anti-cancer drugs. In the present study, we have assessed wogonin, a flavonoid compound isolated from Scutellaria baicalensis Georgi, induced ROS generation, endoplasmic reticulum (ER) stress and cell apoptosis. Wogonin induced cell death in two different human glioma cells, such as U251 and U87 cells but not in human primary astrocytes (IC 50 > 100 μM). Wogonin-induced apoptotic cell death in glioma cells was measured by propidine iodine (PI) analysis, Tunnel assay and Annexin V staining methods. Furthermore, wogonin also induced caspase-9 and caspase-3 activation as well as up-regulation of cleaved PARP expression. Moreover, treatment of wogonin also increased a number of signature ER stress markers glucose-regulated protein (GRP)-78, GRP-94, Calpain I, and phosphorylation of eukaryotic initiation factor-2α (eIF2α). Treatment of human glioma cells with wogonin was found to induce reactive oxygen species (ROS) generation. Wogonin induced ER stress-related protein expression and cell apoptosis was reduced by the ROS inhibitors apocynin and NAC (N-acetylcysteine). The present study provides evidence to support the fact that wogonin induces human glioma cell apoptosis mediated ROS generation, ER stress activation and cell apoptosis.

Utilization of the cellular stress response to sensitize cancer cells to TRAIL-mediated apoptosis

INTRODUCTION

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) is a promising death ligand who has received significant attention due to its specific anti-cancer activity. Recently, a number of clinical trials involving either recombinant soluble TRAIL or agonistic death receptor (DR) antibodies have even been initiated. One major caveat in TRAIL-based anti-cancer therapies is that a considerable number of cancer cells are notorious resistant to apoptosis induction by TRAIL. Overcoming this primary or secondary evolved resistance is an utmost important goal of present cancer research. The current literature suggests that TRAIL resistance is mediated by a number of endogenous factors.

AREAS COVERED

According to recent research, stress-related transcription factors have acquired a pivotal role in the sensitization of highly resistant cancer cells, for example, pancreatic cancer and glioblastoma cells, to TRAIL-mediated cell death. Out of this transcription factor family, C/EBP-homologous protein (CHOP) is linked to the control of DR-mediated apoptosis by modulation of several apoptotic and anti-apoptotic factors. Stress responses in certain organelles, such as endoplasmic reticulum (ER) and mitochondria, are potent inductors of CHOP expression. This report focuses on the influence of stress responses on endogenous or acquired resistance to extrinsic apoptosis in tumor cells and summarizes recent findings and results. The Medline and ClinicalTrials database with key words were used for this review.

EXPERT OPINION

A potential novel treatment strategy for highly treatment-resistant tumors is the induction of a cellular stress response in cancer cells. The induction of an organelle-related stress response, such as nuclear, ER and mitochondrial stress, leads to a dramatic sensitization of a broad variety of cancer cells of different tumor entities to the apoptotic ligand, TRAIL. Importantly, non-neoplastic cells are not sensitized to TRAIL-mediated cell death through the unfolded protein response in most instances, suggesting that this treatment is not only of high efficacy, but even more less of unwanted toxicity in patients.

A synthetic compound, 1,5-bis(2-methoxyphenyl)penta-1,4-dien-3-one (B63), induces apoptosis and activates endoplasmic reticulum stress in non-small cell lung cancer cells

Endoplasmic reticulum (ER) stress-induced cancer cell apoptosis has become a novel signaling target for the development of therapeutic drugs for cancer treatment. Curcumin, a dietary phytochemical, exhibits growth-suppressive activity against cancer cells via multitarget mechanisms. However, the low stability and poor pharmacokinetics significantly limit its clinical applications. Thus, we designed and synthesized a novel monocarbonyl analog of curcumin, 1,5-bis(2-methoxyphenyl) penta-1,4-dien-3-one (B63). This compound exhibited a higher chemical stability in cultural medium and a better intracellular profile than curcumin. Treatment with B63 potently induced apoptosis of human non-small cell lung cancer (NSCLC) cells in a dose-responsive manner, while exhibiting no cytotoxicity in normal lung fibroblast cells. Its antitumor effect was associated with the ER stress-mediated apoptotic pathway and, ultimately, the activation of the caspase cascades. However, curcumin at the same concentrations did not cause ER stress in H460 cells. Further, C/EBP homologous protein knockdown by siRNA attenuated B63-induced cell apoptosis, indicating that the apoptotic pathway is ER stress-dependent. In vivo, the volume and weight of the tumor were reduced significantly by pretreating the H460 tumor cells with B63 before implantation. Taken together, these insights on the novel compound B63, from both chemical and biological perspectives, may provide a novel anticancer candidate for the treatment of NSCLC.

A novel monocarbonyl analogue of curcumin, (1E,4E)-1,5-bis(2,3-dimethoxyphenyl)penta-1,4-dien-3-one, induced cancer cell H460 apoptosis via activation of endoplasmic reticulum stress signaling pathway

Endoplasmic reticulum (ER) stress-induced cancer cell apoptosis has become a novel signaling target for development of cancer therapeutic drugs. Curcumin exhibits growth-suppressive activity against a variety of cancer cells. We previously synthesized a series of monocarbonyl analogues of curcumin with strong cytotoxicity against tumor cells. In this study, we found that only compound 19 [(1E,4E)-1,5-bis(2,3-dimethoxyphenyl)penta-1,4-dien-3-one] can induce C/EBP-homologous protein (CHOP) expression in human lung cancer H460 cells. Treatment with 19 induced H460 cell apoptosis in a dose-responsive manner, and this effect was associated with corresponding increases in a series of key components in ER stress-mediated apoptosis pathway, followed by caspase cleavage and activation. However, curcumin at the same concentrations does not display such properties. CHOP knockdown by specific siRNA attenuated 19-induced cell apoptosis, further indicating that the apoptotic pathway is ER stress-dependent. In vivo, 19 showed a dramatic 53.5% reduction in H460 xenograft tumor size after 22 days of treatment. Taken together, these mechanistic insights on the novel compound 19, with nontoxicity, may provide us with a novel anticancer candidate.