Cyclooxygenase-2 inducing Mcl-1-dependent survival mechanism in human lung adenocarcinoma CL1.0 cells. Involvement of phosphatidylinositol 3-kinase/Akt pathway

Development and Clinical Validation of a Novel 5 Gene Signature Based on Fatty Acid Metabolism-Related Genes in Oral Squamous Cell Carcinoma

BACKGROUND/AIM

Lipid metabolism disorders play a crucial role in tumor development and progression. The aim of the study focused on constructing a novel prognostic model of oral squamous cell carcinoma (OSCC) patients using fatty acid metabolism-related genes.

METHODS

Microarray test and data from The Cancer Genome Atlas (TCGA) were used to identify differentially expressed genes related to fatty acid metabolism. The quantitative real-time polymerase chain reaction (qRT-PCR) was then used to validate the expression of targeted fatty acid metabolism genes. A risk predictive scoring model of fatty acid metabolism-related genes was generated using a multivariate Cox model. The efficacy of this model was assessed by time-dependent receiver operating characteristic curve (ROC).

RESULTS

14 fatty acid metabolism-related genes were identified by microarray test and TCGA database analysis and then confirmed by PCR. Finally, a 5 gene signature (ACACB, FABP3, PDK4, PPARG, and PLIN5) was constructed and a RiskScore was calculated for each patient. Compared to the high RiskScore group, the low RiskScore group had better overall survival (OS) (p = 0.02). The RiskScore derived from a 5 gene signature was a prognostic factor (HR: 3.73, 95% CI: 1.38, 10.09) for OSCC patients. The predictive classification efficiencies of RiskScore were evaluated and the area under the curve (AUC) values for 1, 3, and 5 years were 0.613, 0.652, and 0.681, respectively. Then we compared the predictive performance of the prognostic model with or without the RiskScore. The 5 gene-derived RiskScore can improve the predictive performance with AUC values of 0.760, 0.803, and 0.830 for 1, 3, and 5 years OS in prognostic model including the RiskScore. While the predicted AUC values of the model without RiskScore for 1, 3, and 5 years OS were 0.699, 0.715, and 0.714, respectively.

CONCLUSION

We developed a predictive score model using 5 fatty acid metabolism-related genes, which could be a potential prognostic indicator in OSCC.

Integrative Bioinformatics Study of Tangeretin Potential Targets for Preventing Metastatic Breast Cancer

Agents that target metastasis are important to improve treatment efficacy in patients with breast cancer. Tangeretin, a citrus flavonoid, exhibits antimetastatic effects on breast cancer cells, but its molecular mechanism remains unclear. Tangeretin targets were retrieved from PubChem, whereas metastatic breast cancer regulatory genes were downloaded from PubMed. In total, 58 genes were identified as potential therapeutic target genes of tangeretin (PTs). GO and KEGG pathway enrichment analyses of PTs were performed using WebGestalt (WEB-based Gene SeT AnaLysis Toolkit). The PPI network was analyzed using STRING-DB v11.0 and visualized by Cytoscape software. Hub genes were selected on the basis of the highest degree score as calculated by the CytoHubba plugin. Genetic alterations of the PTs were analyzed using cBioPortal. The prognostic values of the PTs were evaluated with the Kaplan-Meier plot. The expression of PTs across breast cancer samples was confirmed using GEPIA. The reliability of the PTs in metastatic breast cancer cells was validated using ONCOMINE. Molecular docking was performed to foresee the binding sites of tangeretin with PIK3Cα, MMP9, PTGS2, COX-2, and IKK. GO analysis showed that PTs participate in the biological process of stimulus response, are the cellular components of the nucleus and the membrane, and play molecular roles in enzyme regulation. KEGG pathway enrichment analysis revealed that PTs regulate the PI3K/Akt pathway. Genetic alterations for each target gene were MTOR (3%), NOTCH1 (4%), TP53 (42%), MMP9 (4%), NFKB1 (3%), PIK3CA (32%), PTGS2 (15%), and RELA (5%). The Kaplan-Meier plot showed that patients with low mRNA expression levels of MTOR, TP53, MMP9, NFKB1, PTGS2, and RELA and high expression of PIK3CA had a significantly better prognosis than their counterparts. Further validation of gene expression by using GEPIA revealed that the mRNA expression of MMP9 was significantly higher in breast cancer tissues than in normal tissues, whereas the mRNA expression of PTGS2 showed the opposite. Analysis with ONCOMINE demonstrated that the mRNA expression levels of MMP9 and NFKB1 were significantly higher in metastatic breast cancer cells than in normal tissues. The results of molecular docking analyses revealed the advantage of tangeretin as an inhibitor of PIK3CA, MMP9, PTGS2, and IKK. Tangeretin inhibits metastasis in breast cancer cells by targeting TP53, PTGS2, MMP9, and PIK3CA and regulating the PI3K/Akt signaling pathway. Further investigation is needed to validate the results of this study.

MicroRNAs in the anticancer effects of celecoxib: A systematic review

Cyclooxygenase-2 (COX-2) is known as an important enzyme in the inflammation process that has tumorigenesis function in various cancers through the induction of epithelial-to-mesenchymal transition (EMT), cell proliferation, migration, and invasion that lead to metastasis. Celecoxib is a nonsteroidal anti-inflammatory drug (NSAID) that can selectively target COX-2, suppress downstream pathways, and finally lead to anticancer potentiality. microRNAs (miRNAs), as a class of small noncoding RNAs, play pivotal roles in cancers through the tumor-suppressive or oncogenic effects, by post-transcriptional regulation of their target genes. In this regard, shreds of evidence have shown that, COX-2 reveals its action through miRNA regulation. So, in this systematic review, we aimed to highlight the tumorigenic role of COX-2 in cancer development and the therapeutic effects of celecoxib, as a selective COX-2 drug, through the regulation of miRNAs.

PTEN: What we know of the function and regulation of this onco-suppressor factor in bladder cancer?

Bladder cancer accounts for high morbidity and mortality around the world and its incidence rate is suggested to be higher in following years. A number of factors involve in bladder cancer development such as lifestyle and drugs. However, it appears that genetic factors play a significant role in bladder cancer development and progression. Phosphatase and tensin homolog (PTEN) is a cancer-related transcription factor that is corelated with reduced proliferation and invasion of cancer cells by negatively targeting PI3K/Akt/mTOR signaling pathway. In the present review, we aimed to explore the role of PTEN in bladder cancer cells and how upstream modulators affect PTEN in this life-threatening disorder. Down-regulation of PTEN is associated with poor prognosis, chemoresistance and progression of cancer cells. Besides, microRNAs, long non-coding RNAs, circular RNAs and other molecular pathways such as NF-kB are able to target PTEN in bladder cancer cells. Notably, anti-tumor drugs such as kaempferol, β-elemene and sorafenib upregulate the expression of PTEN to exert their inhibitory effects on bladder cancer cells.

Overcoming Resistance of Human Non-Hodgkin's Lymphoma to CD19-CAR CTL Therapy by Celecoxib and Histone Deacetylase Inhibitors

Patients with B-cell non-Hodgkin’s lymphoma (B-NHL) who fail to respond to first-line treatment regimens or develop resistance, exhibit poor prognosis. This signifies the need to develop alternative treatment strategies. CD19-chimeric antigen receptor (CAR) T cell-redirected immunotherapy is an attractive and novel option, which has shown encouraging outcomes in phase I clinical trials of relapsed/refractory NHL. However, the underlying mechanisms of, and approaches to overcome, acquired anti-CD19CAR CD8⁺ T cells (CTL)-resistance in NHL remain elusive. CD19CAR transduced primary human CTLs kill CD19⁺ human NHLs in a CD19- and caspase-dependent manner, mainly via the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) apoptotic pathway. To understand the dynamics of the development of resistance, we analyzed several anti-CD19CAR CTL-resistant NHL sublines (R-NHL) derived by serial exposure of sensitive parental lines to excessive numbers of anti-CD19CAR CTLs followed by a limiting dilution analysis. The R-NHLs retained surface CD19 expression and were efficiently recognized by CD19CAR CTLs. However, R-NHLs developed cross-resistance to CD19CAR transduced human primary CTLs and the Jurkat human T cell line, activated Jurkat, and lymphokine activated killer (LAK) cells, suggesting the acquisition of resistance is independent of CD19-loss and might be due to aberrant apoptotic machinery. We hypothesize that the R-NHL refractoriness to CD19CAR CTL killing could be partially rescued by small molecule sensitizers with apoptotic-gene regulatory effects. Chromatin modifiers and Celecoxib partially reversed the resistance of R-NHL cells to the cytotoxic effects of anti-CD19CAR CTLs and rhTRAIL. These in vitro results, though they require further examination, may provide a rational biological basis for combination treatment in the management of CD19CAR CTL-based therapy of NHL.

PPARγ is critical for Mycobacterium tuberculosis induction of Mcl-1 and limitation of human macrophage apoptosis

Peroxisome proliferator-activated receptor (PPAR)γ is a global transcriptional regulator associated with anti-inflammatory actions. It is highly expressed in alveolar macrophages (AMs), which are unable to clear the intracellular pathogen Mycobacterium tuberculosis (M.tb). Although M.tb infection induces PPARγ in human macrophages, which contributes to M.tb growth, the mechanisms underlying this are largely unknown. We undertook NanoString gene expression analysis to identify novel PPARγ effectors that condition macrophages to be more susceptible to M.tb infection. This revealed several genes that are differentially regulated in response to PPARγ silencing during M.tb infection, including the Bcl-2 family members Bax (pro-apoptotic) and Mcl-1 (pro-survival). Apoptosis is an important defense mechanism that prevents the growth of intracellular microbes, including M.tb, but is limited by virulent M.tb. This suggested that M.tb differentially regulates Mcl-1 and Bax expression through PPARγ to limit apoptosis. In support of this, gene and protein expression analysis revealed that Mcl-1 expression is driven by PPARγ during M.tb infection in human macrophages. Further, 15-lipoxygenase (15-LOX) is critical for PPARγ activity and Mcl-1 expression. We also determined that PPARγ and 15-LOX regulate macrophage apoptosis during M.tb infection, and that pre-clinical therapeutics that inhibit Mcl-1 activity significantly limit M.tb intracellular growth in both human macrophages and an in vitro TB granuloma model. In conclusion, identification of the novel PPARγ effector Mcl-1 has determined PPARγ and 15-LOX are critical regulators of apoptosis during M.tb infection and new potential targets for host-directed therapy for M.tb.

Cinobufagin inhibits tumor growth by inducing intrinsic apoptosis through AKT signaling pathway in human nonsmall cell lung cancer cells

The cinobufagin (CB) has a broad spectrum of cytotoxicity to inhibit cell proliferation of various human cancer cell lines, but the molecular mechanisms still remain elusive. Here we observed that CB inhibited the cell proliferation and tumor growth, but induced cell cycle arrest and apoptosis in a dose-dependent manner in non-small cell lung cancer (NSCLC) cells. Treatment with CB significantly increased the reactive oxygen species but decreased the mitochondrial membrane potential in NSCLC cells. These effects were markedly blocked when the cells were pretreated with N-acetylcysteine, a specific reactive oxygen species inhibitor. Furthermore, treatment with CB induced the expression of BAX but reduced that of BCL-2, BCL-XL and MCL-1, leading to an activation of caspase-3, chromatin condensation and DNA degradation in order to induce programmed cell death in NSCLC cells. In addition, treatment with CB reduced the expressions of p-AKT^T308 and p-AKT^S473 and inhibited the AKT/mTOR signaling pathway in NSCLC cells in a time-dependent manner. Our results suggest that CB inhibits tumor growth by inducing intrinsic apoptosis through the AKT signaling pathway in NSCLC cells.

Prostaglandin receptors induce urothelial tumourigenesis as well as bladder cancer progression and cisplatin resistance presumably via modulating PTEN expression

Background:

We investigated the role of prostaglandin receptors (e.g. prostaglandin E2 receptor 2 (EP2), EP4) and the efficacy of celecoxib in urothelial tumourigenesis and cancer progression.

Methods:

We performed immunohistochemistry in bladder cancer (BC) tissue microarrays, in vitro transformation assay in a normal urothelial SVHUC line, and western blot/reverse transcription–polymerase chain reaction/cell growth assays in BC lines.

Results:

EP2/EP4 expression was elevated in BCs compared with non-neoplastic urothelial tissues and in BCs from those who were resistant to cisplatin-based neoadjuvant chemotherapy. Strong positivity of EP2/EP4 in non-muscle-invasive tumours or positivity of EP2/EP4 in muscle-invasive tumours strongly correlated with disease progression or disease-specific mortality, respectively. In SVHUC cells, exposure to a chemical carcinogen 3-methylcholanthrene considerably increased and decreased the expression of EP2/EP4 and phosphatase and tensin homologue (PTEN), respectively. Treatment with selective EP2/EP4 antagonist or celecoxib also resulted in prevention in 3-methylcholanthrene-induced neoplastic transformation of SVHUC cells. In BC lines, EP2/EP4 antagonists and celecoxib effectively inhibited cell viability and migration, as well as augmented PTEN expression. Furthermore, these drugs enhanced the cytotoxic activity of cisplatin in BC cells. EP2/EP4 and PTEN were also elevated and reduced, respectively, in cisplatin-resistant BC sublines.

Conclusions:

EP2/EP4 activation correlates with induction of urothelial cancer initiation and outgrowth, as well as chemoresistance, presumably via downregulating PTEN expression.

Timosaponin AIII inhibits melanoma cell migration by suppressing COX-2 and in vivo tumor metastasis

Melanoma is the leading cause of death from skin disease, due in large part to its propensity to metastasize. We examined the effects of timosaponin AIII, a compound isolated from Anemarrhena asphodeloides Bunge, on melanoma cancer cell migration and the molecular mechanisms underlying these effects using B16-F10 and WM-115 melanoma cells lines. Overexpression of COX-2, its metabolite prostaglandin E2 (PGE2), and PGE2 receptors (EP2 and EP4) promoted cell migration in vitro. Exposure to timosaponin AIII resulted in concentration-dependent inhibition of cell migration, which was associated with reduced levels of COX-2, PGE2, and PGE2 receptors. Transient transfection of COX-2 siRNA also inhibited cell migration. Exposure to 12-O-tetradecanoylphorbal-13-acetate enhanced cell migration, whereas timosaponin AIII inhibited 12-O-tetradecanoylphorbal-13-acetate-induced cell migration and reduced basal levels of EP2 and EP4. Moreover, timosaponin AIII inhibited activation of nuclear factor-kappa B (NF-κB), an upstream regulator of COX-2 in B16-F10 cells. Consistent with our in vitro findings, in vivo studies showed that timosaponin AIII treatment significantly reduced the total number of metastatic nodules in the mouse lung and improved histological alterations in B16-F10-injected C57BL/6 mice. In addition, C57BL/6 mice treated with timosaponin AIII showed reduced expression of COX-2 and NF-κB in the lung. Together, these results indicate that timosaponin AIII has the capacity to inhibit melanoma cell migration, an essential step in the process of metastasis, by inhibiting expression of COX-2, NF-κB, PGE2, and PGE2 receptors.

Ibuprofen and Diclofenac Restrict Migration and Proliferation of Human Glioma Cells by Distinct Molecular Mechanisms

Background

Non-steroidal anti-inflammatory drugs (NSAIDs) have been associated with anti-tumorigenic effects in different tumor entities. For glioma, research has generally focused on diclofenac; however data on other NSAIDs, such as ibuprofen, is limited. Therefore, we performed a comprehensive investigation of the cellular, molecular, and metabolic effects of ibuprofen and diclofenac on human glioblastoma cells.

Methods

Glioma cell lines were treated with ibuprofen or diclofenac to investigate functional effects on proliferation and cell motility. Cell cycle, extracellular lactate levels, lactate dehydrogenase-A (LDH-A) expression and activity, as well as inhibition of the Signal Transducer and Activator of Transcription 3 (STAT-3) signaling pathway, were determined. Specific effects of diclofenac and ibuprofen on STAT-3 were investigated by comparing their effects with those of the specific STAT-3 inhibitor STATTIC.

Results

Ibuprofen treatment led to a stronger inhibition of cell growth and migration than treatment with diclofenac. Proliferation was affected by cell cycle arrest at different checkpoints by both agents. In addition, diclofenac, but not ibuprofen, decreased lactate levels in all concentrations used. Both decreased STAT-3 phosphorylation; however, diclofenac led to decreased c-myc expression and subsequent reduction in LDH-A activity, whereas treatment with ibuprofen in higher doses induced c-myc expression and less LDH-A alteration.

Conclusions

This study indicates that both ibuprofen and diclofenac strongly inhibit glioma cells, but the subsequent metabolic responses of both agents are distinct. We postulate that ibuprofen may inhibit tumor cells also by COX- and lactate-independent mechanisms after long-term treatment in physiological dosages, whereas diclofenac mainly acts by inhibition of STAT-3 signaling and downstream modulation of glycolysis.

Bioinformatics approach reveals systematic mechanism underlying lung adenocarcinoma

BACKGROUND

The purpose of this work was to explore the systematic molecular mechanism of lung adenocarcinoma and gain a deeper insight into it.

METHODS

Comprehensive bioinformatics methods were applied. Initially, significant differentially expressed genes (DEGs) were analyzed from the Affymetrix microarray data (GSE27262) deposited in the Gene Expression Omnibus (GEO). Subsequently, gene ontology (GO) analysis was performed using online Database for Annotation, Visualization and Integration Discovery (DAVID) software. Finally, significant pathway crosstalk was investigated based on the information derived from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.

RESULTS

According to our results, the N-terminal globular domain of the type X collagen (COL10A1) gene and transmembrane protein 100 (TMEM100) gene were identified to be the most significant DEGs in tumor tissue compared with the adjacent normal tissues. The main GO categories were biological process, cellular component and molecular function. In addition, the crosstalk was significantly different between non-small cell lung cancer pathways and inositol phosphate metabolism pathway, focal adhesion signal pathway, vascular smooth muscle contraction signal pathway, peroxisome proliferator-activated receptor (PPAR) signaling pathway and calcium signaling pathway in tumor.

CONCLUSIONS

Dysfunctional genes and pathways may play key roles in the progression and development of lung adenocarcinoma. Our data provide a systematic perspective for understanding this mechanism and may be helpful in discovering an effective treatment for lung adenocarcinoma.

Overexpression of CRM1: A Characteristic Feature in a Transformed Phenotype of Lung Carcinogenesis and a Molecular Target for Lung Cancer Adjuvant Therapy

Our previous study showed that chromosome region maintenance 1 (CRM1), a nuclear export receptor for various cancer-associated "cargo" proteins, was important in regulating lung carcinogenesis in response to a tobacco carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). The objectives of this study are to comprehensively evaluate the significance of CRM1 in lung cancer development and investigate the therapeutic potential of targeting CRM1 for lung cancer treatment using both in vitro and in vivo models. We showed that CRM1 was overexpressed not only in lung tumor tissues from both lung cancer patients and mice treated with NNK but also in NNK-transformed BEAS-2B human bronchial epithelial cells. Furthermore, stable overexpression of CRM1 in BEAS-2B cells by plasmid vector transfection led to malignant cellular transformation. Moreover, a decreased CRM1 expression level in A549 cells by short hairpin siRNA transfection led to a decreased tumorigenic activity both in vitro and in nude mice, suggesting the potential to target CRM1 for lung cancer treatment. Indeed, we showed that the cytotoxic effects of cisplatin on A549 cells with CRM1 down-regulated by short hairpin siRNA were significantly increased, compared with A549 cells, and the cytotoxic effects of cisplatin became further enhanced when the drug was used in combination with leptomycin B, a CRM1 inhibitor, in both in vitro and in vivo models. Cancer target genes were significantly involved in these processes. These data suggest that CRM1 plays an important role in lung carcinogenesis and provides a novel target for lung cancer adjuvant therapy.

Nonsteroidal Anti-Inflammatory Drug and Aspirin Use in Relation to Lung Cancer Risk among Postmenopausal Women

BACKGROUND

Results from prospective studies suggest that nonsteroidal anti-inflammatory drugs (NSAID) may decrease lung cancer risk; however, any protective effect appears to be most evident in men.

METHODS

We evaluated the associations between NSAID use and lung cancer incidence in postmenopausal women in the Women's Health Initiative (WHI) adjusting for female-specific potential confounders such as hormone therapy in addition to smoking histories and other potential confounders. We identified 143,841 women from ages 50 to 79 and 1,902 centrally confirmed lung cancer cases were included in the analysis. We used Cox regression models to estimate HRs and their 95% confidence intervals (CI).

RESULTS

Compared with nonuse, regular NSAID use was not associated with overall lung cancer incidence (NSAID use >10 years HR 0.87; 95% CI, 0.71-1.08, P(trend) = 0.13). No statistically significant associations were found when examined by histologic subtypes and although there was a trend of decreased risk with longer duration of NSAID use in the adenocarcinoma subtype, this was not statistically significant (NSAID use >10 years HR 0.80; 95% CI, 0.58-1.10; P(trend) = 0.07).

CONCLUSION

Our study did not show that NSAID use is associated with lung cancer risk in women even after adjusting for female-specific confounders. There was a trend of decreased risk in the adenocarcinoma subtype; however, this was not statistically significant.

IMPACT

Future studies will need to take in account the various molecular subtypes of non-small cell lung cancer to further elucidate the role of NSAIDs in lung cancer, especially for the adenocarcinoma subtype.

Interactions between neutrophils and non-small cell lung cancer cells: enhancement of tumor proliferation and inflammatory mediator synthesis

The inflammatory tumor microenvironment plays a crucial role in tumor progression. In lung cancer, both bacterial infections and neutrophilia are associated with a poor prognosis. In this study, we characterized the effect of isolated human neutrophils on proliferation of the non-small cell lung cancer (NSCLC) cell line A549 and analyzed the impact of A549–neutrophil interactions on inflammatory mediator generation in naive and lipopolysaccharide (LPS)-exposed cell cultures. Co-incubation of A549 cells with neutrophils induced proliferation of resting and LPS-exposed A549 cells in a dose-dependent manner. In transwell-experiments, this effect was demonstrated to depend on direct cell-to-cell contact. This pro-proliferative effect of neutrophils on A549 cells could be attenuated by inhibition of neutrophil elastase activity, but not by oxygen radical neutralization. Correspondingly, neutrophil elastase secretion, but not respiratory burst, was specifically enhanced in co-cultures of A549 cells and neutrophils. Moreover, interference with COX-2 activity by indomethacin or the specific COX-2 inhibitor NS-398 also blunted the increased A549 proliferation in the presence of neutrophils. In parallel, a massive amplification of COX-2-dependent prostaglandin E₂ synthesis was detected in A549–neutrophil co-cultures. These findings suggest that direct cell–cell interactions between neutrophils and tumor cells cause release of inflammatory mediators which, in turn, may enhance tumor growth in NSCLC.

Celecoxib increases miR-222 while deterring aromatase-expressing breast tumor growth in mice

Background

Breast cancer is one of the most deadly diseases in women. Inhibiting the synthesis of estrogen is effective in treating patients with estrogen-responsive breast cancer. Previous studies have demonstrated that use of cyclooxygenase (COX) inhibitors is associated with reduced breast cancer risk.

Methods

In the present study, we employed an established mouse model for postmenopausal breast cancer to evaluate the potential mechanisms of the COX-2 inhibitor celecoxib. Aromatase-expressing MCF-7 cells were transplanted into ovariectomized athymic mice. The animals were given celecoxib at 1500 ppm or aspirin at 200 ppm by oral administration with androstenedione injection.

Results

Our results showed that both COX inhibitors could suppress the cancer xenograft growth without changing the plasma estrogen level. Protein expression of ERα, COX-2, Cyclin A, and Bcl-xL were reduced in celecoxib-treated tumor samples, whereas only Bcl-xL expression was suppressed in those treated with aspirin. Among the breast cancer-related miRNAs, miR-222 expression was elevated in samples treated with celecoxib. Further studies in culture cells verified that the increase in miR-222 expression might contribute to ERα downregulation but not the growth deterrence of cells.

Conclusion

Overall, this study suggested that both celecoxib and aspirin could prevent breast cancer growth by regulating proteins in the cell cycle and apoptosis without blocking estrogen synthesis. Besides, celecoxib might affect miR expression in an undesirable fashion.

Curcumin and vitamin E protect against adverse effects of benzo[a]pyrene in lung epithelial cells

Benzo[a]pyrene (BaP), a well-known environmental carcinogen, promotes oxidative stress and DNA damage. Curcumin and vitamin E (VE) have potent antioxidative activity that protects cells from oxidative stress and cellular damage. The objectives of the present study were to investigate the adverse effects of BaP on normal human lung epithelial cells (BEAS-2B), the potential protective effects of curcumin and VE against BaP-induced cellular damage, and the molecular mechanisms of action. MTT assay, flow cytometry, fluorescence microplate assay, HPLC, qRT-PCR, and western blot were performed to analyze cytotoxicity, cell cycle, reactive oxygen species (ROS), BaP diol-epoxidation (BPDE)-DNA adducts, gene expression, and protein expression, respectively. Curcumin or VE prevented cells from BaP-induced cell cycle arrest and growth inhibition, significantly suppressed BaP-induced ROS levels, and decreased BPDE-DNA adducts. While CYP1A1 and 1B1 were induced by BaP, these inductions were not significantly reduced by curcumin or VE. Moreover, the level of activated p53 and PARP-1 were significantly induced by BaP, whereas this induction was markedly reduced after curcumin and VE co-treatment. Survivin was significantly down-regulated by BaP, and curcumin significantly restored survivin expression in BaP-exposed cells. The ratio of Bax/Bcl-2 was also significantly increased in cells exposed to BaP and this increase was reversed by VE co-treatment. Taken together, BaP-induced cytotoxicity occurs through DNA damage, cell cycle arrest, ROS production, modulation of metabolizing enzymes, and the expression/activation of p53, PARP-1, survivin, and Bax/Bcl-2. Curcumin and VE could reverse some of these BaP-mediated alterations and therefore be effective natural compounds against the adverse effects of BaP in lung cells.

Melatonin overcomes apoptosis resistance in human hepatocellular carcinoma by targeting survivin and XIAP

Apoptosis resistance in hepatocellular carcinoma (HCC) is one of the most significant factors for hepatocarcinogenesis and tumor progression, and leads to resistance to conventional chemotherapy. It is well known that inhibitor of apoptosis proteins (IAPs) play key roles in apoptosis resistance, it has become an important target for antitumor therapy. In this study, we examined if melatonin, the main secretory product of the pineal gland, targeted IAPs, leading to the inhibition of apoptosis resistance. To accomplish this, we first observed that four members of IAPs (cIAP-1, cIAP-2, survivin, and XIAP) were overexpressed in human HCC tissue. Interestingly, melatonin significantly inhibited the growth of HepG2 and SMMC-7721 cells and promoted apoptosis along with the downregulation of survivin and XIAP, but had no effect on the expression of cIAP-1 and cIAP-2. These data suggest that the inhibition of survivin and XIAP by melatonin may play an important part in reversing apoptosis resistance. Notably, cIAP-1, survivin and XIAP were significantly associated with the coexpression of COX-2 in human HCC specimens. Melatonin also reduced the expression of COX-2 and inhibited AKT activation in HepG2 and SMMC-7721 cells. Inhibition of COX-2 activity with the selective inhibitor, NS398, and inhibition of AKT activation using the PI3K inhibitor, LY294002, in tumor cells confirmed that melatonin-induced apoptosis was COX-2/PI3K/AKT-dependent, suggesting that the COX-2/PI3K/AKT pathway plays a role in melatonin inhibition of IAPs. Taken together, these results suggest that melatonin overcomes apoptosis resistance by the suppressing survivin and XIAP via the COX-2/PI3K/AKT pathway in HCC cells.

Cyclooxygenase-2 over-expression inhibits liver apoptosis induced by hyperglycemia

Increased expression of COX-2 has been linked to inflammation and carcinogenesis. Constitutive expression of COX-2 protects hepatocytes from several pro-apoptotic stimuli. Increased hepatic apoptosis has been observed in experimental models of diabetes. Our present aim was to analyze the role of COX-2 as a regulator of apoptosis in diabetic mouse liver. Mice of C57BL/6 strain wild type (Wt) and transgenic in COX-2 (hCOX-2 Tg) were separated into Control (vehicle) and SID (streptozotocin induced diabetes, 200 mg/kg body weight, i.p.). Seven days post-injection, Wt diabetic animals showed a decrease in PI3K activity and P-Akt levels, an increase of P-JNK, P-p38, pro-apoptotic Bad and Bax, release of cytochrome c and activities of caspases-3 and -9, leading to an increased apoptotic index. This situation was improved in diabetic COX-2 Tg. In addition, SID COX-2 Tg showed increased expression of anti-apoptotic Mcl-1 and XIAP. Pro-apoptotic state in the liver of diabetic animals was improved by over-expression of COX-2. We also analyzed the roles of high glucose-induced apoptosis and hCOX-2 in vitro. Non-transfected and hCOX-2-transfected cells were cultured at 5 and 25 mM of glucose by 72 h. At 25 mM there was an increase in apoptosis in non-transfected cells versus those exposed to 5 mM. This increase was partly prevented in transfected cells at 25 mM. Moreover, the protective effect observed in hCOX-2-transfected cells was suppressed by addition of DFU (COX-2 selective inhibitor), and mimicked by addition of PGE(2) in non-transfected cells. Taken together, these results demonstrate that hyperglycemia-induced hepatic apoptosis is protected by hCOX-2 expression.

Inhibition of Metastatic Potential in Breast Carcinoma In Vivo and In Vitro through Targeting VEGFRs and FGFRs

Angiogenesis and lymphangiogenesis are considered to play key roles in tumor metastasis. Targeting receptor tyrosine kinases essentially involved in the angiogenesis and lymphangiogenesis would theoretically prevent cancer metastasis. However, the optimal multikinase inhibitor for metastasis suppression has yet to be developed. In this study, we evaluated the effect of NSTPBP 0100194-A (194-A), a multikinase inhibitor of vascular endothelial growth factor receptors (VEGFRs)/fibroblast growth factor receptors (FGFRs), on lymphangiogenesis and angiogenesis in a mammary fat pad xenograft model of the highly invasive breast cancer cell line 4T1-Luc⁺. We investigated the biologic effect of 194-A on various invasive breast cancer cell lines as well as endothelial and lymphatic endothelial cells. Intriguingly, we found that 194-A drastically reduced the formation of lung, liver, and lymph node metastasis of 4T1-Luc⁺ and decreased primary tumor growth. This was associated with significant reductions in intratumoral lymphatic vessel length (LVL) and microvessel density (MVD). 194-A blocked VEGFRs mediated signaling on both endothelial and lymphatic endothelial cells. Moreover, 194-A significantly inhibited the invasive capacity induced by VEGF-C or FGF-2 in vitro in both 4T1 and MDA-MB231 cells. In conclusion, these experimental results demonstrate that simultaneous inhibition of VEGFRs/FGFRs kinases may be a promising strategy to prevent breast cancer metastasis.

Gallic acid: molecular rival of cancer

Gallic acid, a predominant polyphenol, has been shown to inhibit carcinogenesis in animal models and in vitro cancerous cell lines. The inhibitory effect of gallic acid on cancer cell growth is mediated via the modulation of genes which encodes for cell cycle, metastasis, angiogenesis and apoptosis. Gallic acid inhibits activation of NF-κB and Akt signaling pathways along with the activity of COX, ribonucleotide reductase and GSH. Moreover, gallic acid activates ATM kinase signaling pathways to prevent the processes of carcinogenesis. The data so far available, both from in vivo and in vitro studies, indicate that this dietary polyphenol could be promising agent in the field of cancer chemoprevention.

Endotoxin induces proliferation of NSCLC in vitro and in vivo: role of COX-2 and EGFR activation

Lung cancer is frequently complicated by pulmonary infections which may impair prognosis of this disease. Therefore, we investigated the effect of bacterial lipopolysaccharides (LPS) on tumor proliferation in vitro in the non-small cell lung cancer (NSCLC) cell line A549, ex vivo in a tissue culture model using human NSCLC specimens and in vivo in the A549 adenocarcinoma mouse model. LPS induced a time- and dose-dependent increase in proliferation of A549 cells as quantified by MTS activity and cell counting. In parallel, an increased expression of the proliferation marker Ki-67 and cyclooxygenase (COX)-2 was detected both in A549 cells and in ex vivo human NSCLC tissue. Large amounts of COX-2-derived prostaglandin (PG)E(2) were secreted from LPS-stimulated A549 cells. Pharmacological interventions revealed that the proliferative effect of LPS was dependent on CD14 and Toll-like receptor (TLR)4. Moreover, blocking of the epidermal growth factor receptor (EGFR) also decreased LPS-induced proliferation of A549 cells. Inhibition of COX-2 activity in A549 cells severely attenuated both PGE(2) release and proliferation in response to LPS. Synthesis of PGE(2) was also reduced by inhibiting CD14, TLR4 and EGFR in A549 cells. The proliferative effect of LPS on A549 cells could be reproduced in the A549 adenocarcinoma mouse model with enhancement of tumor growth and Ki-67 expression in implanted tumors. In summary, LPS induces proliferation of NSCLC cells in vitro, ex vivo in human NSCLC specimen and in vivo in a mouse model of NSCLC. Pulmonary infection may thus directly induce tumor progression in NSCLC.

Arsenic trioxide synergizes with everolimus (Rad001) to induce cytotoxicity of ovarian cancer cells through increased autophagy and apoptosis

Phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin pathway plays a key role in the tumorigenesis of a variety of human cancers including ovarian cancer. However, inhibitors of this pathway such as Rad001 have not shown therapeutic efficacy as a single agent for this cancer. Arsenic trioxide (ATO) induces an autophagic pathway in ovarian carcinoma cells. We found that ATO can synergize with Rad001 to induce cytotoxicity of ovarian cancer cells. Moreover, we identified synergistic induction of autophagy and apoptosis as the likely underlying mechanism that is responsible for the enhanced cytotoxicity. The enhanced cytotoxicity is accompanied by decreased p-AKT levels as well as upregulation of ATG5-ATG12 conjugate and LC3-2, hallmarks of autophagy. Rad001 and ATO can also synergistically inhibit tumors in a xenograft animal model of ovarian cancer. These results thus identify and validate a novel mechanism to enhance and expand the existing targeted therapeutic agent to treat human ovarian cancer.

Expression of the aryl hydrocarbon receptor pathway and cyclooxygenase-2 in dog tumors

In humans, the aryl hydrocarbon receptor (AHR) gene battery constitutes a set of contaminant-responsive genes, which have been recently shown to be involved in the regulation of several patho-physiological conditions, including tumorigenesis. As the domestic dog represents a valuable animal model in comparative oncology, mRNA levels of cytochromes P450 1A1, 1A2 and 1B1 (CYP1A1, 1A2 and 1B1), AHR, AHR nuclear translocator (ARNT), AHR repressor (AHRR, whose partial sequence was here obtained) and cyclooxygenase-2 (COX2) were measured in dog control tissues (liver, skin, mammary gland and bone), in 47 mast cell tumors (MCTs), 32 mammary tumors (MTs), 5 osteosarcoma (OSA) and related surgical margins. Target genes were constitutively expressed in the dog, confirming the available human data. Furthermore, their pattern of expression in tumor biopsies was comparable to that already described in a variety of human cancers; in particular, both AHR and COX2 genes were up-regulated and positively correlated, while CYP1A1 and CYP1A2 mRNAs were generally poorly expressed. This work demonstrated for the first time that target mRNAs are expressed in neoplastic tissues of dogs, thereby increasing the knowledge about dog cancer biology and confirming this species as an useful animal model for comparative studies on human oncology.

Protective effect of plaunotol against doxorubicin-induced renal cell death

In searching for a safe and effective compound to be used as a chemoprotective agent to prevent toxicity of the anthracyclin doxorubicin to renal cells, the present study demonstrated that plaunotol, a purified acyclic diterpene from Croton stellatopilosus Ohba, showed potential protection against doxorubicin-induced cell death in human proximal tubule cells. Treatment of renal cells with doxorubicin resulted in a significant decrease in viability of the cells, and we next proved that such toxicity was mainly due to apoptotic cell death. Pretreatment of the cells with plaunotol for at least 9 h prior to doxorubicin exposure improved the cells' survival. Plaunotol was shown to up-regulate the anti-apoptotic myeloid cell leukemia-1 (Mcl-1) level whereas it had no effect on the Bcl-2 level. The reduction in Mcl-1 after doxorubicin treatment was shown to be closely associated with the toxic action of the drug, and the increase in Mcl-1 induced by plaunotol pretreatment was able to prevent cell death induced by doxorubicin. Furthermore, the protective effect of plaunotol was evaluated in human lung and melanoma cells. Results indicated that plaunotol had no significantly protective effect in human lung carcinoma cells, whereas it sensitized melanoma cells to drug-induced cell death.

Myeloid suppressor cells and immune modulation in lung cancer

Many tumors, including lung cancers, promote immune tolerance to escape host immune surveillance and facilitate tumor growth. Tumors utilize numerous pathways to inhibit immune responses, including the elaboration of immune-suppressive mediators such as PGE2, TGF-β, IL-10, VEGF, GM-CSF, IL-6, S100A8/A9 and SCF, which recruit and/or activate myeloid-derived suppressor cells (MDSCs). MDSCs, a subset of heterogeneous bone marrow-derived hematopoietic cells, are found in the peripheral blood of cancer patients and positively correlate to malignancy. Solid tumors contain MDSCs that maintain an immune-suppressive network in the tumor microenvironment. This review will focus on the interaction of tumors with MDSCs that lead to dysregulation of antigen presentation and T-cell activities in murine tumor models. Specific genetic signatures in lung cancer modulate the activities of MDSCs and impact tumor progression. Targeting MDSCs may have a long-term antitumor benefit and is at the forefront of anticancer therapeutic strategies.

WWOX induces apoptosis and inhibits proliferation of human hepatoma cell line SMMC-7721

AIM: To investigate the effects of the WWOX gene on the human hepatic carcinoma cell line SMMC-7721.

METHODS: Full-length WWOX cDNA was amplified from normal human liver tissues. Full-length cDNA was subcloned into pEGFP-N1, a eukaryotic expression vector. After introduction of the WWOX gene into cancer cells using liposomes, the WWOX protein level in the cells was detected through Western blotting. Cell growth rates were assessed by methyl thiazolyl tetrazolium (MTT) and colony formation assays. Cell cycle progression and cell apoptosis were measured by flow cytometry. The phosphorylated protein kinase B (AKT) and activated fragments of caspase-9 and caspase-3 were examined by Western blotting analysis.

RESULTS: WWOX significantly inhibited cell proliferation, as evaluated by the MTT and colony formation assays. Cells transfected with WWOX showed significantly higher apoptosis ratios when compared with cells transfected with a mock plasmid, and overexpression of WWOX delayed cell cycle progression from G1 to S phase, as measured by flow cytometry. An increase in apoptosis was also indicated by a remarkable activation of caspase-9 and caspase-3 and a dephosphorylation of AKT (Thr308 and Ser473) measured with Western blotting analysis.

CONCLUSION: Overexpression of WWOX induces apoptosis and inhibits proliferation of the human hepatic carcinoma cell line SMMC-7721.

The novel NF-κB inhibitor DHMEQ synergizes with celecoxib to exert antitumor effects on human liver cancer cells by a ROS-dependent mechanism

In a previous work of ours dehydroxymethyl-epoxyquinomicin (DHMEQ), an inhibitor of NF-κB, was shown to induce apoptosis through Reactive Oxygen Species (ROS) production in hepatoma cells. The present study demonstrated that DHMEQ cooperates with Celecoxib (CLX) to decrease NF-κB DNA binding and to inhibit cell growth and proliferation more effectively than treatment with these single agents alone in the hepatoma cell lines HA22T/VGH and Huh-6. ROS production induced by the DHMEQ-CLX combination in turn generated the expression of genes involved in endoplasmic reticulum (ER) stress and silencing TRB3 mRNA significantly decreased DHMEQ-CLX-induced cell growth inhibition. Moreover, the DHMEQ-CLX combination was associated with induction of PARP cleavage and down-regulation of the anti-apoptotic proteins Bcl-2, Mcl-1 and survivin, as well as activated Akt. CD95 and CD95 ligand expression increased synergistically in the combination treatment, which was reversed in the presence of NAC. Knockdown of CD95 mRNA expression significantly decreased DHMEQ-CLX-induced cell growth inhibition in both cell lines. These data suggest that the DHMEQ-CLX combination kills hepatoma cells via ROS production, ER stress response and the activation of intrinsic and extrinsic apoptotic pathways.

Green tea catechins reduce invasive potential of human melanoma cells by targeting COX-2, PGE2 receptors and epithelial-to-mesenchymal transition

Melanoma is the most serious type of skin disease and a leading cause of death from skin disease due to its highly metastatic ability. To develop more effective chemopreventive agents for the prevention of melanoma, we have determined the effect of green tea catechins on the invasive potential of human melanoma cells and the molecular mechanisms underlying these effects using A375 (BRAF-mutated) and Hs294t (Non-BRAF-mutated) melanoma cell lines as an in vitro model. Employing cell invasion assays, we found that the inhibitory effects of green tea catechins on the cell migration were in the order of (-)-epigallocatechin-3-gallate (EGCG)>(-)-epigallocatechin>(-)-epicatechin-3-gallate>(-)-gallocatechin>(-)-epicatechin. Treatment of A375 and Hs294t cells with EGCG resulted in a dose-dependent inhibition of cell migration or invasion of these cells, which was associated with a reduction in the levels of cyclooxygenase (COX)-2, prostaglandin (PG) E₂ and PGE₂ receptors (EP2 and EP4). Treatment of cells with celecoxib, a COX-2 inhibitor, also inhibited melanoma cell migration. EGCG inhibits 12-O-tetradecanoylphorbol-13-acetate-, an inducer of COX-2, and PGE₂-induced cell migration of cells. EGCG decreased EP2 agonist (butaprost)- and EP4 agonist (Cay10580)-induced cell migration ability. Moreover, EGCG inhibited the activation of NF-κB/p65, an upstream regulator of COX-2, in A375 melanoma cells, and treatment of cells with caffeic acid phenethyl ester, an inhibitor of NF-κB, also inhibited cell migration. Inhibition of melanoma cell migration by EGCG was associated with transition of mesenchymal stage to epithelial stage, which resulted in an increase in the levels of epithelial biomarkers (E-cadherin, cytokeratin and desmoglein 2) and a reduction in the levels of mesenchymal biomarkers (vimentin, fibronectin and N-cadherin) in A375 melanoma cells. Together, these results indicate that EGCG, a major green tea catechin, has the ability to inhibit melanoma cell invasion/migration, an essential step of metastasis, by targeting the endogenous expression of COX-2, PGE₂ receptors and epithelial-to-mesenchymal transition.

Interaction of celecoxib with different anti-cancer drugs is antagonistic in breast but not in other cancer cells

Celecoxib, an inhibitor of cyclooxygenase-2, is being investigated for enhancement of chemotherapy efficacy in cancer clinical trials. This study investigates the ability of cyclooxygenase-2 inhibitors to sensitize cells from different origins to several chemotherapeutic agents. The effect of the drug's mechanism of action and sequence of administration are also investigated. The sensitivity, cell cycle, apoptosis and DNA damage of five different cancer cell lines (HeLa, HCT116, HepG2, MCF7 and U251) to 5-FU, cisplatin, doxorubicin and etoposide±celecoxib following different incubation schedules were analyzed. We found antagonism between celecoxib and the four drugs in the breast cancer cells MCF7 following all incubation schedules and between celecoxib and doxorubicin in all cell lines except for two combinations in HCT116 cells. Celecoxib with the other three drugs in the remaining four cell lines resulted in variable interactions. Mechanistic investigations revealed that celecoxib exerts different molecular effects in different cells. In some lines, it abrogates the drug-induced G2/M arrest enhancing pre-mature entry into mitosis with damaged DNA thus increasing apoptosis and resulting in synergism. In other cells, it enhances drug-induced G2/M arrest allowing time to repair drug-induced DNA damage before entry into mitosis and decreasing cell death resulting in antagonism. In some synergistic combinations, celecoxib-induced abrogation of G2/M arrest was not associated with apoptosis but permanent arrest in G1 phase. These results, if confirmed in-vivo, indicate that celecoxib is not a suitable chemosensitizer for breast cancer or with doxorubicin for other cancers. Moreover, combination of celecoxib with other drugs should be tailored to the tumor type, drug and administration schedule.

Terbinafine inhibits oral squamous cell carcinoma growth through anti-cancer cell proliferation and anti-angiogenesis

Terbinafine (TB), an oral antifungal agent used in the treatment of superficial mycosis, has been reported to exert an anti-tumor effect in various cancer cells. However, the effect of TB on oral cancer has not been evaluated. Herein we demonstrate that TB (0-60 µM) concentration-dependently decreased cell number in cultured human oral squamous cell carcinoma (OSCC), KB cells. The anti-proliferation effect of TB was also observed in two other OSCC cell lines, SAS and SCC 15. TB (60 µM) was not cytotoxic and its inhibition on KB cell growth was reversible. [(3) H]thymidine incorporation and flow cytometric analyses revealed that TB-inhibited DNA synthesis and induced the G0/G1 cell-cycle arrest. The TB-induced cell-cycle arrest occurred when the cyclin-dependent kinase 2 activity was inhibited just as the protein levels of p21(cip1) and p27(kip1) were increased. The TB-induced G0/G1 cell-cycle arrest was completely blocked when the expressions of p21(cip1) and p27(kip1) were knocked-down together. Taken together, these results suggest that the p21(cip1) - and p27(kip1) -associated signaling pathways might be involved in the TB-induced anti-proliferation in KB cells. In vivo, TB (50 mg/kg, i.p.) significantly inhibited the KB tumor size. In these TB-treated tumors, increases in the levels of p21(cip1) and p27(kip1) protein and decreases in the number of proliferating cell nuclear antigen-positive cells and the microvessel density were observed. These findings demonstrate for the first time that TB might have potential to serve as a therapeutic tool in the treatment of oral cancer.

The correlation between tumor-infiltrating Foxp3+ regulatory T cells and cyclooxygenase-2 expression and their association with recurrence in resected head and neck cancers

The aim of this study was to investigate the correlation between tumor-infiltrating CD4+ CD25(high) Foxp3+ naturally occurring regulatory T cells (Foxp3+ nTregs) and cyclooxygenase-2 (COX-2) expression and their association with local recurrence in resected head and neck cancers. Intratumoral COX-2 and Foxp3+ nTregs expressions were retrospectively assessed using immunohistochemistry. Associations between the clinicopathological characteristics and either intratumoral COX-2 expression or number of Foxp3+ nTregs were tested using the Chi-square test. The correlation between the number of Foxp3+ nTregs and COX-2 expression was tested using Spearman's rank correlation test. Associations between recurrence-free survival (RFS) and either intratumoral COX-2 expression or number of Foxp3+ nTregs were calculated using the Kaplan-Meier method, and factors that may influence the RFS were analyzed by Cox regression. The five-year RFS for all patients was 35.09%. Patient clinicopathological characteristics had no relationship with intratumoral COX-2 expression or the number of Foxp3+ nTregs. However, a positive correlation between intratumoral COX-2 expression and the number of Foxp3+ nTregs was observed (P < 0.001). The RFS of patients with elevated COX-2 expression was significantly worse than that of patients without intratumoral COX-2 expression (P = 0.0228). The RFS of patients with tumors containing >6 Foxp3+ cells was significantly worse than that of patients with tumors containing ≤6 Foxp3+ cells (P = 0.0020). However, by Cox regression analysis, the RFS of all patients was not influenced by intratumoral COX-2 expression (P = 0.100) or the number of Foxp3+ nTregs (P = 0.071). Tumor-infiltrating CD4+ CD25(high) Foxp3+ nTregs were positively correlated with intratumoral COX-2 expression and were associated with a worse RFS in univariate analysis.

Targeting apoptosis pathways by Celecoxib in cancer

Celecoxib is a paradigmatic selective inhibitor of cyclooxygenase-2 (COX-2). This anti-inflammatory drug has potent anti-tumor activity in a wide variety of human epithelial tumor types, such as colorectal, breast, non-small cell lung, and prostate cancers. Up to now, the drug found application in cancer prevention in patients with familial adenomatous polyposis. Moreover, the use of Celecoxib is currently tested in the prevention and treatment of pancreatic, breast, ovarian, non-small cell lung cancer and other advanced human epithelial cancers. Induction of apoptosis contributes to the anti-neoplastic activity of Celecoxib. In most cellular systems Celecoxib induces apoptosis independently from its COX-2 inhibitory action via a mitochondrial apoptosis pathway which is however, not inhibited by overexpression of Bcl-2. In addition, Celecoxib exerts antagonistic effects on the anti-apoptotic proteins Mcl-1 and survivin. Consequently, the use of Celecoxib may be of specific value for the treatment of apoptosis-resistant tumors with overexpression of Bcl-2, Mcl-1, or survivin as single drug or in combination with radiotherapy, chemotherapy, or targeted pro-apoptotic drugs that are inhibited by survivin, Bcl-2 or Mcl-1. As COX-2 inhibition has been associated with cardiovascular toxicity, the value of drug derivatives without COX-2 inhibitory action should be validated for prevention and treatment of human epithelial tumors to reduce the risk for heart attack or stroke. However, its additional COX-2 inhibitory action may qualify Celecoxib for a cautious use in COX-2-dependent epithelial tumors, where the drug could additionally suppress COX-2-mediated growth and survival promoting signals from the tumor and the stromal cells.

Activated PI3K/Akt/COX-2 pathway induces resistance to radiation in human cervical cancer HeLa cells

Activation of Akt, or protein kinase B, is frequently observed in human cancers. It has been demonstrated that PI3K activation leads to radiation resistance. Here, the role of PI3K/Akt/COX-2 pathway in the resistance to radiation in human cervical cancer HeLa cells is explored. Cultured HeLa cells were randomly assigned to five treatment groups: control, radiation, LY294002, PI3K antagonist, and the COX-2-antagonist celecoxib, with the objective of determining the role of PI3K/Akt/COX-2 pathway in the radiation resistance of HeLa cells. The cell survival ratios were computed by clone formation. To calculate the quasi-threshold dose (Dq), mean lethal dose (D(0)), survival fraction at 2 Gy radiation dose (SF(2)), and radiosensitization ratio, the cell survival curves were fitted to the one-hit multitarget model. The protein expression profiles for pAkt, Akt, COX-2, Bad, and pBad were detected by Western blot analysis, and the mRNA expression profiles for COX-2 and Bad were analyzed by RT-polymerase chain reaction. Treatment with a combination of celecoxib, LY294002, and radiation resulted in elevated Dq, D(0), and SF(2), and increased radiosensitivity in HeLa cells. The PI3K/Akt/COX-2 pathway was activated by radiation, whereas celecoxib inhibited the activation of the PI3K/Akt/COX-2 axis through several targets. Our results indicate that the activated PI3K/Akt/COX-2 signal transduction pathway was the main cause for decline in radiosensitivity in HeLa cells. This study proposes that the inhibition of the PI3K/Akt/COX-2 pathway can synergistically enhance radiation efficacy.

Berberine, an isoquinoline alkaloid, inhibits melanoma cancer cell migration by reducing the expressions of cyclooxygenase-2, prostaglandin E₂ and prostaglandin E₂ receptors

Melanoma is the leading cause of death from skin disease due, in large part, to its propensity to metastasize. We have examined the effect of berberine, an isoquinoline alkaloid, on human melanoma cancer cell migration and the molecular mechanisms underlying these effects using melanoma cell lines, A375 and Hs294. Using an in vitro cell migration assay, we show that over expression of cyclooxygenase (COX)-2, its metabolite prostaglandin E₂ (PGE₂) and PGE₂ receptors promote the migration of cells. We found that treatment of A375 and Hs294 cells with berberine resulted in concentration-dependent inhibition of migration of these cells, which was associated with a reduction in the levels of COX-2, PGE₂ and PGE₂ receptors (EP2 and EP4). Treatment of cells with celecoxib, a COX-2 inhibitor, or transient transfection of cells with COX-2 small interfering RNA, also inhibited cell migration. Treatment of the cells with 12-O-tetradecanoylphorbol-13-acetate (TPA), an inducer of COX-2 or PGE₂, enhanced cell migration, whereas berberine inhibited TPA- or PGE₂-promoted cell migration. Berberine reduced the basal levels as well as PGE₂-stimulated expression levels of EP2 and EP4. Treatment of the cells with the EP4 agonist stimulated cell migration and berberine blocked EP4 agonist-induced cell migration activity. Moreover, berberine inhibited the activation of nuclear factor-kappa B (NF-κB), an upstream regulator of COX-2, in A375 cells, and treatment of cells with caffeic acid phenethyl ester, an inhibitor of NF-κB, inhibited cell migration. Together, these results indicate for the first time that berberine inhibits melanoma cell migration, an essential step in invasion and metastasis, by inhibition of COX-2, PGE₂ and PGE₂ receptors.

β-Sitosterol inhibits cell cycle progression of rat aortic smooth muscle cells through increases of p21cip1 protein

Abnormal proliferation of vascular smooth muscle cells (VSMCs) plays a central role in the pathogenesis of atherosclerosis. β-Sitosterol, an important phytosterol found in plant food, is known to exert antiatherosclerosis activity. However, the molecular mechanisms underlying β-sitosterol-induced antiproliferation of VSMCs were still not clear. This study demonstrated that β-sitosterol (1-20 μM) concentration-dependently inhibited proliferation of rat aortic smooth muscle cells (RASMCs) without cytotoxic effect. Flow cytometric analysis revealed that β-sitosterol arrested cell cycle progression through down-regulation of cyclin E and cyclin-dependent kinase (CDK)2 and up-regulation of p21cip1. In the β-sitosterol-treated RASMCs, the formation of the CDK2-p21cip1 complex was increased and the assayable CDK2 activity was decreased. Knockdown of the expression of p21cip1 gene prevented β-sitosterol-induced cell cycle arrest in RASMCs. In conclusion, β-sitosterol inhibited VSMC proliferation by increasing the levels of p21cip1 protein, which in turn inhibited the CDK2 activity, and finally interrupted the progress of the cell cycle.

Tumor-infiltrating Foxp3+ regulatory T cells are correlated with cyclooxygenase-2 expression and are associated with recurrence in resected non-small cell lung cancer

BACKGROUND

Cyclooxygenase-2 (COX-2) is constitutively overexpressed in a variety of epithelial malignancies and is usually associated with a poor prognosis. COX-2-derived prostaglandin E2 transforms CD4+CD25+ T regulatory (Treg) cells (Tregs), and Tregs are thought to moderate the antitumor immune response. Herein, we investigated the prognostic value of tumor-infiltrating Treg cells and their correlation with COX-2 expression in resected non-small cell lung cancer (NSCLC).

MATERIAL AND METHODS

Intratumoral COX-2 and Treg expression were retrospectively assessed using immunohistochemistry in paraffin-embedded samples from 100 patients who had undergone complete resections for NSCLC. The expressions of COX-2 and Foxp3, which was most specific Treg cell marker, were compared with the clinicopathological variables, and the correlation between Foxp3+ Tregs and COX-2 expression was analyzed.

RESULTS

The recurrence-free survival (RFS) of patients with elevated COX-2 expression was significantly worse than that of patients without COX-2 expression. Tumor-infiltrating Foxp3-positive lymphocytes were positively correlated with COX-2 expression. The median count for Foxp3-positive lymphocytes was 3 (minimum-maximum, 0-24) in 10 high-power fields. The RFS of patients with tumors containing >or=3 Foxp3-positive cells (Foxp3 expression group) was significantly worse than that of patients with tumors containing <3 Foxp3-positive cells. In a multivariate analysis, only nodal status was an independent predictor of a significantly shorter RFS. However, in node-negative NSCLC, Foxp3 expression was an independent predictor of a significantly shorter RFS.

CONCLUSIONS

Tumor-infiltrating Foxp3+ Tregs were positively correlated with intratumoral COX-2 expression and were associated with a worse RFS, especially among patients with node-negative NSCLC.

COX-2 inhibitor celecoxib improves radiosensitivity of human colon carcinoma cell line SW480

AIM: To determine whether celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, can improve radiosensitivity of human colon carcinoma cell line SW480.

METHODS: Cultured SW480 cells were treated with celecoxib for 24 h and then irradiated with different doses of X-rays. Cell survival was evaluated by colony formation assay. To calculate Dq, D0, SF2 and SER, the cell survival curve was fitted by the one-hit multi-target model. After 6-Gy radiation, the apoptosis of SW480 cells was detected by flow cytometry, and the expression of pAkt, COX-2, and pBad in SW480 cells was detected by Western blot.

RESULTS: The Dq, D0 and SF2 values for irradiated SW480 cells pretreated with celecoxib were lower than those for unpretreated ones (0.995 vs 2.527, 1.091 vs 1.622 and 0.352 vs 0.805, respectively; all P < 0.05). The SER for irradiated SW480 cells pretreated with celecoxib was 1.487. X-ray radiation enhanced the expression of pAkt, COX-2 and pBad proteins in SW480 cells. The expression levels of pAkt, COX-2 and pBad proteins in irradiated SW480 cells pretreated with celecoxib were lower than those in unpretreated ones. The apoptosis rate was significantly higher in irradiated SW480 cells pretreated with celecoxib than in unpretreated ones (15.02 ± 2.16 vs 6.25 ± 1.22, P < 0.05).

CONCLUSION: Celecoxib improves radiosensitivity of human colon carcinoma cell line SW480 perhaps by inhibiting the activation of the PI3K/Akt/COX-2 pathway.

Cellular uptake, subcellular distribution and toxicity of arsenic compounds in methylating and non-methylating cells

Arsenic is a known human carcinogen, inducing tumors of the skin, urinary bladder, liver and lung. Inorganic arsenic, existing in highly toxic trivalent and significantly less toxic pentavalent forms, is methylated to mono- and di-methylated species mainly in the liver. Due to the low toxicity of pentavalent methylated species, methylation has been regarded as a detoxification process for many years; however, recent findings of a high toxicity of trivalent methylated species have indicated the contrary. In order to elucidate the role of speciation and methylation for the toxicity and carcinogenicity of arsenic, systematic studies were conducted comparing cellular uptake, subcellular distribution as well as toxic and genotoxic effects of organic and inorganic pentavalent and trivalent arsenic species in both non-methylating (urothelial cells and fibroblasts) and methylating cells (hepatocytes). The membrane permeability was found to be dependent upon both the arsenic species and the cell type. Uptake rates of trivalent methylated species were highest and exceeded those of their pentavalent counterparts by several orders of magnitude. Non-methylating cells (urothelial cells and fibroblasts) seem to accumulate higher amounts of arsenic within the cell than the methylating hepatocytes. Cellular uptake and extrusion seem to be faster in hepatocytes than in urothelial cells. The correlation of uptake with toxicity indicates a significant role of membrane permeability towards toxicity. Furthermore, cytotoxic effects are more distinct in hepatocytes. Differential centrifugation studies revealed that elevated concentrations of arsenic are present in the ribosomal fraction of urothelial cells and in nucleic and mitochondrial fractions of hepatic cells. Further studies are needed to define the implications of the observed enrichment of arsenic in specific cellular organelles for its carcinogenic activity. This review summarizes our recent research on cellular uptake, distribution and toxicity of arsenic compounds in methylating and non-methylating cells.

Effects of CAY10404 on the PKB/Akt and MAPK pathway and apoptosis in non-small cell lung cancer cells

BACKGROUND AND OBJECTIVE

Lung cancer is the most common cause of cancer death in men and women worldwide. The mechanism of cell death induced by CAY10404, a highly selective cyclooxygenase-2 inhibitor, was evaluated in three non-small cell lung cancer (NSCLC) cell lines (H460, H358, H1703).

METHODS

To measure the effects of CAY10404 on proliferation of NSCLC cells, 3 x 10(3) cells/well were plated in 96-well plates and allowed to adhere overnight at 37 degrees C. After treatment with CAY10404 for 3 days, cell proliferation was measured by the 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In the H460 NSCLC cells, evidence of apoptosis was sought using the terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labelling (TUNEL) assay and western blot analysis.

RESULTS

Treatment with CAY10404 in the range of 10-100 microM caused dose-dependent growth inhibition, with an average 50% inhibitory concentration (IC(50)) of 60-100 micromol/L, depending on the cell line. Western blot analysis of CAY10404-treated cells showed cleavage of poly (ADP-ribose) polymerase (PARP) and procaspase-3, signifying caspase activity and apoptotic cell death. CAY10404 treatment inhibited the phosphorylation of Akt, glycogen synthase kinase-3beta and extracellular signal-regulated kinases 1/2 in H460 and H358 cells.

CONCLUSIONS

These results suggest that CAY10404 is a potent inducer of apoptosis in NSCLC cells, and that it may act by suppressing multiple protein kinase B/Akt and mitogen-activated protein kinase pathways.

PC-407, a celecoxib derivative, inhibited the growth of colorectal tumor in vitro and in vivo

This study aimed to observe the growth-inhibitory effect of PC-407 (4-[5-naphthyl-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzenesulfonamide), a celecoxib derivative synthesized in our lab, in human colorectal cancer cells and a colitis-associated colorectal cancer (CACC) model, and investigate the relative molecular mechanisms. SW-1116 (expressing a high level of cyclooxygenase-2 [COX-2]), HT-29 (expressing a moderate level of COX-2), and SW-480 (no expression of COX-2) cell lines were exposed to different concentrations of celecoxib (0-100 micromol/L) or PC-407 (0-100 micromol/L). Then, COX-2 levels were assessed by reverse transcription-PCR and Western blotting. COX-2 activity was evaluated by measuring prostaglandin E(2) concentration using enzyme-linked immunoassay. A mouse model of colitis-associated carcinogenesis was employed to determine the effect of PC-407 in vivo. PC-407 inhibited cell growth in a concentration-dependent manner, and the IC(50) values of PC-407 for growth inhibition of SW-1116, HT-29, and SW-480 cells were 17.60 +/- 3.02, 18.14 +/- 2.81, and 8.13 +/- 0.40 micromol/L, respectively. PC-407 down-regulated COX-2 mRNA and protein levels and reduced prostaglandin E(2) production significantly. In vivo, PC-407 inhibited the genesis of CACC effectively. Our data indicate that PC-407 can inhibit the growth of tumor both in vitro and in vivo and suggest that the effect probably involves inhibition of the COX-2 pathway and other COX-2-independent pathways.

Expression of p-Akt and COX-2 in Gastric Adenocarcinomas and Adenovirus Mediated Akt1 and COX-2 ShRNA Suppresses SGC-7901 Gastric Adenocarcinoma and U251 Glioma Cell Growth In Vitro and In Vivo

Cyclooxygenase-2 (COX-2) and Protein kinase B (PKB/Akt) play a crucial role in the formation of many malignant tumors and have been shown to be the important therapeutic targets. In the present study, we examined immunohistochemical expression of phosphorylated Akt (p-Akt) and COX-2 in 45 gastric adenocarcinomas with different tumor grades. Then, adenovirus-mediated small hairpin RNA (shRNA) expression vectors rAd5-Akt1+COX-2 (rAd5-A+C) that target sequences of human COX-2 and Akt1 were used to examine the inhibitory effects on cell proliferation, invasion and apoptosis in SGC7901 gastric adenocarcinoma and U251 glioma cells. Cell growth was inhibited by over 70%, as indicated by a MTT assay, and was accompanied by G1/G0 phase arrest in the rAd5-A+C treated group, indicating poor cell growth activities. The number of cells invading through the matrigel in the rAd5-A+C treated group was significantly decreased (36.2±3.1) compared with that of the control group SGC7901 (105.0±4.0) and the nonsense sequence group rAd5-HK (102.5±6.4). In addition, the tumor volumes in the SGC7901 subcutaneous nude mouse model treated with rAd5-A+C was significantly smaller than those of the control group and nonsense sequence group rAd5-HK. When COX-2 and Akt1 were dramatically downregulated, Ki-67, CyclinD1, MMP-2, MMP-9 and Bcl-2 were also downregulated. Our results demonstrated that p-Akt and COX-2 were overexpressed in gastric adenocarcinomas and their expression levels were elevated with the ascending order of tumor malignancy; rAd5-A+C targeting COX-2 and Akt1 down-regulated their expression significantly in a sequence-specific manner, exerting inhibitory effects on SGC7901 and U251 cell proliferation, invasion and apoptosis. In conclusion, our data suggest a novel mechanism for the regulation of malignant tumor cell growth and provide evidence for combined gene therapy for malignant tumors.

Acquired activation of the Akt/cyclooxygenase-2/Mcl-1 pathway renders lung cancer cells resistant to apoptosis

Acquired apoptosis resistance plays an important role in acquired chemoresistance in cancer cells during chemotherapy. Our previous observations demonstrated that acquired tumor necrosis factor-related apoptosis-inducing ligand resistance in lung cancer cells was associated with Akt-mediated stabilization of cellular FLICE-like inhibitory protein (c-FLIP) and Mcl-1. In this report, we determined that these cells also have acquired resistance to apoptosis induced by chemotherapeutics such as cisplatin and doxorubicin (Adriamycin), which was detected in vitro in cell cultures and in vivo in xenografted tumors. We further found that cyclooxygenase-2 (COX-2) is dramatically overexpressed in cells with acquired apoptosis resistance. COX-2 seems to be a crucial mediator in acquired apoptosis resistance because suppressing COX-2 activity with a chemical inhibitor or reducing COX-2 protein expression level with COX-2 small interfering RNA dramatically alleviated resistance to therapeutic-induced apoptosis. Inhibiting Akt markedly suppressed COX-2 expression, suggesting COX-2 is a downstream effector of this cell survival kinase-mediated apoptosis resistance. Furthermore, the expression of Mcl-1 but not c-FLIP was significantly reduced when COX-2 was suppressed, and knockdown of Mcl-1 substantially sensitized the cells to apoptosis. Our results establish a novel pathway that consists of Akt, COX-2, and Mcl-1 for acquired apoptosis resistance, which could be a molecular target for circumventing acquired chemoresistance in lung cancer.