Impacts of cytosolic phospholipase A2, 15-prostaglandin dehydrogenase, and cyclooxygenase-2 expressions on tumor progression in colorectal cancer

The tumor suppressor role and epigenetic regulation of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in cancer and tumor microenvironment (TME)

Oxidative stress and inflammation may initiate carcinogenesis and facilitate metastasis via activation of pro-inflammatory signaling network. The side product of arachidonic acid processing by cyclooxygenase-2 (COX-2), the prostaglandin E2 (PGE2), plays a key role in various metabolic disorders and during inflammation-mediated tumorigenesis. It has been demonstrated that PGE2 increases the proliferation, migration, invasion, metastasis, and resistance of cancer cells to apoptosis and other forms of programmed cell death. The expression level of PGE2 metabolizing enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is often decreased in various malignancies. However, the role of 15-PGDH and PGE2 in the regulation of carcinogenesis remains controversial. Numerous cancer cell lines and mouse models have demonstrated the role of 15-PGDH as a tumor suppressor. Downregulation of 15-PGDH increased cancer cell proliferation, migration, anchorage independent growth, colony formation while overexpression reversed these effects, by inducing apoptosis and cell cycle arrest in vitro and in vivo. The expression of 15-PGDH is regulated by various mechanisms, including (a) epigenetic alterations (methylation of promoter region, histone deacetylases, microRNAs (miR-21, miR-26a/b, miR-106b-5p, miR-146b-3p, miR-155, miR-218-5p, and miR-620)); and (b) dysregulated oxidative stress and associated mediators (elevated levels of growth factors and proinflammatory cytokines (such as IL1β and TNFα)). Several transcription factors, such as HNF3β, β-catenin, Snail, Slug, can bind to 15-PGDH promoter region and downregulate the enzyme expression. In contrast, the expression of 15-PGDH can be upregulated by several anti-inflammatory cytokines and anti-cancer agents, such as IL10 and vitamin D. The functional activity of 15-PGDH protein can be modulated by signaling effectors and oxidative stress, including increased production of reactive oxygen species (ROS). However, the role of oxidative stress regulator protein, i.e., nuclear factor erythroid 2-related factor 2 (Nrf2), in the control of 15-PGDH expression remains unclear. This article provides insights and comprehensive overview of the tumor suppressor role of 15-PGDH in various cancers. Epigenetic and post-translational mechanisms regulating 15-PGDH expression and the role of novel ROS-Nrf2-15-PGDH axis were discussed and accented as potential drug targets.

Non-Targeted Serum Lipidomics Analysis and Potential Biomarkers of Laryngeal Cancer Based on UHPLC-QTOF-MS

Laryngeal cancer is a common head and neck malignant cancer type. However, effective biomarkers for diagnosis are lacking and pathogenesis is unclear. Lipidomics is a powerful tool for identifying biomarkers and explaining disease mechanisms. Hence, in this study, non-targeted lipidomics based on ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry (UHPLC-QTOF-MS) were applied to screen the differential lipid metabolites in serum and allowed for exploration of the remodeled lipid metabolism of laryngeal cancer, laryngeal benign tumor patients, and healthy crowds. Multivariate analysis and univariate analysis were combined to screen for differential lipid metabolites among the three groups. The results showed that, across a total of 57 lipid metabolic markers that were screened, the regulation of the lipid metabolism network occurred mainly in phosphatidylcholine (PC), lysophosphatidylcholine (LPC), and sphingomyelin (SM) metabolism. Of note, the concentration levels of sphingolipids 42:2 (SM 42:2) and sphingolipids 42:3 (SM 42:3) correlated with laryngeal cancer progression and were both significantly different among the three groups. Both of them could be considered as potential biomarkers for diagnosis and indicators for monitoring the progression of laryngeal cancer. From the perspective of lipidomics, this study not only revealed the regulatory changes in the lipid metabolism network, but also provided a new possibility for screening biomarkers in laryngeal cancer.

Upregulation of Prostaglandin E2 by Inducible Microsomal Prostaglandin E Synthase-1 in Colon Cancer

Purpose

Prostaglandin E₂ (PGE₂) is known to promote carcinogenesis and cancer progression in colon cancer. Enzymes involved in the metabolism of PGE₂ include cyclooxygenase (COX)-2, microsomal prostaglandin E synthase-1 (mPGES-1), and 15-prostaglandin dehydrogenase (15-PGDH). The current study aims to determine how PGE₂ is expressed by examining patients with colorectal cancer and evaluating colon cancer cells to gain insight into changes in relevant enzymes upon induction of PGE₂.

Methods

The concentration of PGE₂ was measured in tumor tissues and adjacent normal mucosal tissues of 26 patients with colon cancer. The expression of COX-1, COX-2, mPGES-1, and 15-PGDH proteins was measured. The concentration of PGE₂ in FET colon cancer cells was measured both in the initial status and after stimulation by tumor necrosis factor (TNF)-α. The expression levels of PGE₂-related enzymes were measured as well.

Results

There was no significant difference in the average concentration of PGE₂, which was measured at 453.1 pg/mL in cancer tissues and 401.2 pg/mL in normal mucosa. Among PGE₂-related enzymes, 15-PGDH was expressed at a lower level in tumor cells than in normal mucosa. In colon cancer cells, PGE₂ was found to be upregulated upon stimulation by TNF-α, which led to strong induction of mPGES-1 without any change in the expression of COX-2 among the PGE₂-related enzymes.

Conclusion

These results demonstrated that PGE₂ can be induced by stimuli such as TNF-α, and suggest that activation of mPGES-1 is more closely related than that of COX-2 in the induction of PGE₂ on colon cancer.

Mechanism of Apoptosis Induced by Curcumin in Colorectal Cancer

Colorectal cancer (CRC) is among the top three cancer with higher incident and mortality rate worldwide. It is estimated that about over than 1.1 million of death and 2.2 million new cases by the year 2030. The current treatment modalities with the usage of chemo drugs such as FOLFOX and FOLFIRI, surgery and radiotherapy, which are usually accompanied with major side effects, are rarely cured along with poor survival rate and at higher recurrence outcome. This trigger the needs of exploring new natural compounds with anti-cancer properties which possess fewer side effects. Curcumin, a common spice used in ancient medicine was found to induce apoptosis by targeting various molecules and signaling pathways involved in CRC. Disruption of the homeostatic balance between cell proliferation and apoptosis could be one of the promoting factors in colorectal cancer progression. In this review, we describe the current knowledge of apoptosis regulation by curcumin in CRC with regard to molecular targets and associated signaling pathways.

CD147 and Cyclooxygenase Expression in Feline Oral Squamous Cell Carcinoma

Feline oral squamous cell carcinoma (OSCC) is a highly invasive form of cancer in cats. In human OSCC, cluster of differentiation 147 (CD147) contributes to inflammation and tumor invasiveness. CD147 is a potential therapeutic target, but the expression of CD147 in feline OSCC has not been examined. Immunohistochemistry was used to determine if cyclooxygenase 2 (COX-2) and CD147 expression in feline OSCC biopsies was coordinated. Tumor cells were more likely to express COX-2 (22/43 cases or 51%) compared to stroma (8/43 or 19%) and adjacent oral epithelium (9/31 cases or 29%) (p < 0.05). CD147 was also more likely to occur in tumor cells compared to stroma and adjacent mucosa, with 21/43 (49%) of cases having >50% tumor cells with mild or moderate CD147 expression, compared to 9/28 (32%) in adjacent epithelium and only 5/43 (12%) in adjacent stroma (p < 0.05). In feline OSCC cell lines (SCCF1, SCCF2, and SCCF3), CD147 gene expression was more consistently expressed compared to COX-2, which was 60-fold higher in SCCF2 cells compared to SCCF1 cells (p < 0.05). CD147 expression did not correlate with COX-2 expression and prostaglandin E2 (PGE2) secretion, indicating that they may be independently regulated. CD147 potentially represents a novel therapeutic target for the treatment of feline OSCC and further study of CD147 is warranted.

GP. Nanoliposomal delivery of cytosolic phospholipase A2 inhibitor arachidonyl trimethyl ketone for melanoma treatment

Drug resistance and toxicity are major limitations of cancer treatment and frequently occurs during melanoma therapy. Nanotechnology can decrease drug resistance by improving drug delivery, with limited toxicity. This study details the development of nanoparticles containing arachidonyl trifluoromethyl ketone (ATK), a cytosolic phospholipase A₂ inhibitor, which can inhibit multiple key pathways responsible for the development of recurrent resistant disease. Free ATK is toxic, limiting its efficacy as a therapeutic agent. Hence, a novel nanoliposomal delivery system called NanoATK was developed, which loads 61.7% of the compound and was stable at 4^oC for 12 weeks. The formulation decreased toxicity-enabling administration of higher doses, which was more effective at inhibiting melanoma cell growth compared to free-ATK. Mechanistically, NanoATK decreased cellular proliferation and triggered apoptosis to inhibit melanoma xenograft tumor growth without affecting animal weight. Functionally, it inhibited the cPLA₂, AKT, and STAT3 pathways. Our results suggest the successful preclinical development of a unique nanoliposomal formulation containing ATK for the treatment of melanoma.

Targeting cytosolic phospholipase A2 α in colorectal cancer cells inhibits constitutively activated protein kinase B (AKT) and cell proliferation

A constitutive activation of protein kinase B (AKT) in a hyper-phosphorylated status at Ser473 is one of the hallmarks of anti-EGFR therapy-resistant colorectal cancer (CRC). The aim of this study was to examine the role of cytosolic phospholipase A2α (cPLA2α) on AKT phosphorylation at Ser473 and cell proliferation in CRC cells with mutation in phosphoinositide 3-kinase (PI3K). AKT phosphorylation at Ser473 was resistant to EGF stimulation in CRC cell lines of DLD-1 (PIK3CAE545K mutation) and HT-29 (PIK3CAP499T mutation). Over-expression of cPLA2α by stable transfection increased basal and EGF-stimulated AKT phosphorylation and proliferation in DLD-1 cells. In contrast, silencing of cPLA2α with siRNA or inhibition with Efipladib decreased basal and EGF-stimulated AKT phosphorylation and proliferation in HT-29. Treating animals transplanted with DLD-1 with Efipladib (10 mg/kg, i.p. daily) over 14 days reduced xenograft growth by >90% with a concomitant decrease in AKT phosphorylation. In human CRC tissue, cPLA2α expression and phosphorylation were increased in 63% (77/120) compared with adjacent normal mucosa determined by immunohistochemistry. We conclude that cPLA2α is required for sustaining AKT phosphorylation at Ser473 and cell proliferation in CRC cells with PI3K mutation, and may serve as a potential therapeutic target for treatment of CRC resistant to anti-EGFR therapy.

Group IVA Cytosolic Phospholipase A2 Regulates the G2-to-M Transition by Modulating the Activity of Tumor Suppressor SIRT2

The G2-to-M transition (or prophase) checkpoint of the cell cycle is a critical regulator of mitotic entry. SIRT2, a tumor suppressor gene, contributes to the control of this checkpoint by blocking mitotic entry under cellular stress. However, the mechanism underlying both SIRT2 activation and regulation of the G2-to-M transition remains largely unknown. Here, we report the formation of a multiprotein complex at the G2-to-M transition in vitro and in vivo. Group IVA cytosolic phospholipase A2 (cPLA2α) acts as a bridge in this complex to promote binding of SIRT2 to cyclin A-Cdk2. Cyclin A-Cdk2 then phosphorylates SIRT2 at Ser331. This phosphorylation reduces SIRT2 catalytic activity and its binding affinity to centrosomes and mitotic spindles, promoting G2-to-M transition. We show that the inhibitory effect of cPLA2α on SIRT2 activity impacts various cellular processes, including cellular levels of histone H4 acetylated at K16 (Ac-H4K16) and Ac-α-tubulin. This regulatory effect of cPLA2α on SIRT2 defines a novel function of cPLA2α independent of its phospholipase activity and may have implications for the impact of SIRT2-related effects on tumorigenesis and age-related diseases.

Berberine induces apoptosis by suppressing the arachidonic acid metabolic pathway in hepatocellular carcinoma

Berberine (BBR) has been suggested as a potential candidate anticancer agent due to its high anticancer activity and multiple mechanisms. In the present study, the inhibitory effect of BBR on hepatocellular carcinoma (HCC) via the suppression of the arachidonic acid (AA) metabolic pathway was investigated. BBR was demonstrated to reduce the viabilities of H22, HepG2 and Bel‑7404 cells, in a dose‑ and time‑dependent manner, and increase the number of apoptotic cells. BBR induced the translocation of apoptosis‑inducing factor between the mitochondria and the nucleus, and had no effects on the protein expression levels of caspase‑3 or ‑9. In addition, BBR significantly suppressed the protein expression levels of cytosolic phospholipase A2 (cPLA2) and cyclooxygenase (COX)‑2 and elevated the content ratio of AA to prostaglandin E2 (PGE2). Furthermore, BBR reduced the volume and weight of tumors in a H22 transplanted tumor model in mice. The results of the present study demonstrated that elevation in the ratio of AA to PGE2 via suppression of the protein expression of cPLA2 and COX‑2 in the AA metabolic pathway is involved in the inhibitory effect of BBR in HCC.

Impact of combined proglumide and celecoxib on cell proliferation and PGE2 secretion in human gastric cancer cell line BGC-823

AIM: To investigate the effect of proglumide (a gastrin receptor antagonist) and celecoxib [a selective cyclooxygenase-2 (COX-2) inhibitor] on cell proliferation and COX-2, 15-hydroxyprostaglandin dehydrogenase (15-PGDH) and prostaglandin E2 (PGE2) expression in human gastric cancer cell line BGC-823.

METHODS: BGC-823 cells were treated with proglumide and celecoxib, alone or in combination. MTT assay was used to detect the proliferation of BGC-823 cells. Real-time PCR was used to detect COX-2 and 15-PGDH mRNA expression. Western blot was used to detect COX-2 and 15-PGDH protein expression, and ELISA was used to determine the content of PGE2 in culture medium.

RESULTS: Proglumide and celecoxib inhibited the growth of BGC-823 cells in a dose- and time-dependent manner. Treatment with combined proglumide (6 mmol/L, less than IC₅₀) and celecoxib (50 μmol/L, less than IC₅₀) for 48 h was associated with a significantly higher inhibition rate than either of the agents alone (65.1% ± 7.7% vs 38.1% ± 7.1%, 32.6% ± 3.3%, P < 0.05). Proglumide and celecoxib down-regulated the expression of COX-2 mRNA and protein, and up-regulated the expression of 15-PGDH mRNA and protein in BGC-823 cells, and the effects of combined treatment were more significant than treatment with either of the agents alone (P < 0.05 vs proglumide; P < 0.01 vs celecoxib). Proglumide and celecoxib reduced the secretion of PGE2, and the effects of combined treatment were more significant than either of the agents alone (P < 0.05 vs proglumide; P < 0.01 vs celecoxib).

CONCLUSION: Proglumide and celecoxib inhibit the growth of cultured BGC-823 cells time- and dose-dependently, possibly by down-regulating the expression of COX-2 mRNA and protein, up-regulating the expression of 15-PGDH mRNA and protein, and reducing PGE2 synthesis or secretion. Combined use of proglumide and celecoxib has a synergistic effect.

Expression of 15-hydroxyprostaglandin dehydrogenase and cyclooxygenase-2 in non-small cell lung cancer: Correlations with angiogenesis and prognosis

The aim of the present study was to investigate the function of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) and cyclooxygenase-2 (COX-2) in angiogenesis and their association with the prognosis of non-small cell lung cancer (NSCLC). Using immunohistochemical staining, the expression of 15-PGDH and COX-2, and the microvessel density (MVD) levels were evaluated in 35 NSCLC specimens. Paracancerous normal lung tissue was collected as control samples from six patients. The correlation of 15-PGDH with COX-2, clinicopathological characteristics, MVD and overall survival (OS) was studied. NSCLC tissues showed a significantly lower expression level of 15-PGDH (P=0.009) and a significantly higher expression level of COX-2 (P=0.004) compared with normal lung tissue. The expression level of 15-PGDH was negatively correlated with MVD (P<0.001) and COX-2 expression (P=0.032). A low expression level of 15-PGDH, a high expression level of COX-2 and high levels of MVD were significantly correlated with a shorter OS time (15-PGDH, P<0.0001; COX-2, P=0.038; MVD, P<0.0001). This study provided clinical evidence that a low expression level of 15-PGDH is associated with a poor prognosis in NSCLC. Furthermore, it was shown that 15-PGDH and COX-2 reciprocally regulate cancer angiogenesis, which may affect the prognosis of patients with NSCLC.

Human colon adenocarcinoma HT-29 cell: electrochemistry and nicotine stimulation

Recently, it was demonstrated that colorectal cancer HT-29 cells can secrete epinephrine (adrenaline) in an autocrine manner to auto-stimulate cellular growth by adrenoreceptors activation, and that this secretion is enhanced by nicotine, showing an indirect relation between colorectal cancer and tobacco. The electrochemical behaviour of human colon adenocarcinoma HT-29 cells from a colorectal adenocarcinoma cell line, the hormone and neurotransmitter epinephrine, and nicotine, were investigated by cyclic voltammetry, using indium tin oxide (ITO), glassy carbon (GC) and screen printed carbon (SPC) electrodes. The oxidation of the HT-29 cells, previously grown onto ITO or SPC surfaces, followed an irreversible oxidation process that involved the formation of a main oxidation product that undergoes irreversible reduction, as in the epinephrine oxidation mechanism. The effect of nicotine stimulation of the HT-29 cells was also investigated. Nicotine, at different concentration levels 1, 2 and 15 mM, was introduced in the culture medium and an increase with incubation time, 0 to 3h and 30 min, of the HT-29 cells oxidation and reduction peaks was observed. The interaction of nicotine with the HT-29 cells stimulated the epinephrine secretion causing an increase in epinephrine release concentration, and enabling the conclusion that epinephrine and nicotine play an important role in the colorectal tumour growth.

Prognostic implication of 15-hydroxyprostaglandin dehydrogenase down-regulation in patients with colorectal cancer

PURPOSE

Prostaglandin (PG) E2 is known to be closely related to cancer progression and is inactivated by 15-hydroxyprostaglandin dehydrogenase (PGDH). 15-PGDH is shown to have tumor suppressor activity and to be down-regulated in various cancers, including colorectal cancer (CRC). Therefore, we evaluated the expression of 15-PGDH and its prognostic effect in patients with CRC.

METHODS

15-PGDH expression was examined by using immunohistochemistry in 77 patients with CRC. Its prognostic significance was statistically evaluated.

RESULTS

Negative 15-PGDH expression was noted in 55.8% of the 77 cases of CRC. 15-PGDH expression showed no correlation with any of the various clinicopathologic parameters. The status of lymph node metastasis, tumor-node-metastasis stages, and pre-operative carcinoembryonic antigen levels showed significant prognostic effect. However, univariate analysis revealed down-regulation of 15-PGDH not to be a predictor of poor survival. The 5-year overall survival rate was 71.7% in the group with positive expression of 15-PGDH and 67.1% in the group with negative expression of 15-PGDH, but this difference was not statistically significant (P = 0.751).

CONCLUSION

15-PGDH was down-regulated in 55.8% of the colorectal cancer patients. However, down-regulation of 15-PGDH showed no prognostic value in patients with CRC. Further larger scale or prospective studies are needed to clarify the prognostic effect of 15-PGDH down-regulation in patients with colorectal cancer.

PLA2G4A mutants modified protective effect of tea consumption against colorectal cancer

PURPOSE

The primary aim was to respectively evaluate PLA2G4A mutants modifying protective effect of tea consumption against colorectal cancer (CRC), colon and rectal cancer.

METHODS

All participants were recruited from January 2006 to April 2008. The information about tea consumption was collected by a structured questionnaire. CRC patients were diagnosed based on histology. Four single-nuclear polymorphisms (SNPs) in PLA2G4A gene were selected. Multiple logistic regression models were used for assessing the joint effects between tea consumption and SNPs on CRC, colon and rectal cancer.

RESULTS

Three hundred patients with CRC and 296 controls well-matched were used in the final analyses. The significant individual associations between four SNPs (rs6666834, rs10911933, rs4650708 and rs7526089) and CRC were not observed. However, their CTAC haplotype was significantly associated with the increased risk of CRC (OR = 3.06; 95%CI = 1.52-6.19), compared with TCAC haplotype. Drinking tea was correlated with a decreased risk of CRC after adjustment for covariates (OR = 0.61; 95%CI = 0.39-0.97). Meanwhile, compared with no-tea drinkers with TT/CT genotype of rs6666834, tea drinkers with TT/CT or CC had significant lower risk of CRC (OR = 0.6, 95%CI = 0.36-1.00 for TT/CT; 0.38, 0.19-0.74 for CC). The joint effects between the remaining three SNPs and drinking tea on CRC were observed as well. Similar findings were observed on colon and rectal cancers.

CONCLUSIONS

Tea consumption and haplotype of mutants in PLA2G4A gene were respectively associated with the risk of CRC. PLA2G4A mutants modified the protective effect of tea consumption against CRC, colon and rectal cancers in Chinese population.

Delineating metabolic signatures of head and neck squamous cell carcinoma: phospholipase A2, a potential therapeutic target

A better understanding of molecular pathways involved in malignant transformation of head and neck squamous cell carcinoma (HNSCC) is essential for the development of novel and efficient anti-cancer drugs. To delineate the global metabolism of HNSCC, we report (1)H NMR-based metabolic profiling of HNSCC cells from five different patients that were derived from various sites of the upper aerodigestive tract, including the floor of mouth, tongue and larynx. Primary cultures of normal human oral keratinocytes (NHOK) from three different donors were used for comparison. (1)H NMR spectra of polar and non-polar extracts of cells were used to identify more than thirty-five metabolites. Principal component analysis performed on the NMR data revealed a clear classification of NHOK and HNSCC cells. HNSCC cells exhibited significantly altered levels of various metabolites that clearly revealed dysregulation in multiple metabolic events, including Warburg effect, oxidative phosphorylation, energy metabolism, TCA cycle anaplerotic flux, glutaminolysis, hexosamine pathway, osmo-regulatory and anti-oxidant mechanism. In addition, significant alterations in the ratios of phosphatidylcholine/lysophosphatidylcholine and phosphocholine/glycerophosphocholine, and elevated arachidonic acid observed in HNSCC cells reveal an altered membrane choline phospholipid metabolism (MCPM). Furthermore, significantly increased activity of phospholipase A(2) (PLA(2)), particularly cytosolic PLA(2) (cPLA(2)) observed in all the HNSCC cells confirm an altered MCPM. In summary, the metabolomic findings presented here can be useful to further elucidate the biological aspects that lead to HNSCC, and also provide a rational basis for monitoring molecular mechanisms in response to chemotherapy. Moreover, cPLA(2) may serve as a potential therapeutic target for anti-cancer therapy of HNSCC.

HT-29 human colon cancer cell proliferation is regulated by cytosolic phospholipase A(2)α dependent PGE(2)via both PKA and PKB pathways

Cytosolic phospholipase A(2)α (cPLA(2)α) up-regulation has been reported in human colorectal cancer cells, thus we aimed to elucidate its role in the proliferation of the human colorectal cancer cell line, HT-29. EGF caused a rapid activation of cPLA(2)α which coincided with a significant increase in cell proliferation. The inhibition of cPLA(2)α activity by pyrrophenone or by antisense oligonucleotide against cPLA(2)α (AS) or inhibition of prostaglandin E(2) (PGE(2)) production by indomethacin resulted with inhibition of cell proliferation, that was restored by addition of PGE(2). The secreted PGE(2) activated both protein kinase A (PKA) and PKB/Akt pathways via the EP2 and EP4 receptors. Either, the PKA inhibitor (H-89) or the PKB/Akt inhibitor (Ly294002) caused a partial inhibition of cell proliferation which was restored by PGE(2). But, inhibited proliferation in the presence of both inhibitors could not be restored by addition of PGE(2). AS or H-89, but not Ly294002, inhibited CREB activation, suggesting that CREB activation is mediated by PKA. AS or Ly294002, but not H-89, decreased PKB/Akt activation as well as the nuclear localization of β-catenin and cyclin D1 and increased the plasma membrane localization of β-catenin with E-cadherin, suggesting that these processes are regulated by the PKB pathway. Similarly, Caco-2 cells exhibited cPLA(2)α dependent proliferation via activation of both PKA and PKB/Akt pathways. In conclusion, our findings suggest that the regulation of HT-29 proliferation is mediated by cPLA(2)α-dependent PGE(2) production. PGE(2)via EP induces CREB phosphorylation by the PKA pathway and regulates β-catenin and cyclin D1 cellular localization by PKB/Akt pathway.

Identification and development of mPGES-1 inhibitors: where we are at?

Microsomal prostaglandin E synthase-1 (mPGES-1) is the terminal synthase responsible for the synthesis of the pro-tumorigenic prostaglandin E(2) (PGE(2)). mPGES-1 is overexpressed in a wide variety of cancers. Since its discovery in 1997 by Bengt Samuelsson and collaborators, the enzyme has been the object of over 200 peer-reviewed articles. Although today mPGES-1 is considered a validated and promising therapeutic target for anticancer drug discovery, challenges in inhibitor design and selectivity are such that up to this date there are only a few published records of small-molecule inhibitors targeting the enzyme and exhibiting some in vivo anticancer activity. This review summarizes the structures, and the in vitro and in vivo activities of these novel mPGES-1 inhibitors. Challenges that have been encountered are also discussed.

Phase II study of the effects of ginger root extract on eicosanoids in colon mucosa in people at normal risk for colorectal cancer

Inhibitors of COX indicate that upregulation of inflammatory eicosanoids produced by COX, and in particular prostaglandin E(2) (PGE(2)), are early events in the development of colorectal cancer (CRC). Ginger has shown downregulation of COX in vitro and decreased incidence/multiplicity of adenomas in rats. This study was conducted to determine if 2.0 g/d of ginger could decrease the levels of PGE(2), 13-hydroxy-octadecadienoic acids, and 5-, 12-, and 15-hydroxyeicosatetraenoic acid (5-, 12-, and 15-HETE), in the colon mucosa of healthy volunteers. To investigate this aim, we randomized 30 subjects to 2.0 g/d ginger or placebo for 28 days. Flexible sigmoidoscopy at baseline and day 28 was used to obtain colon biopsies. A liquid chromatography mass spectrometry method was used to determine eicosanoid levels in the biopsies, and levels were expressed per protein or per free arachidonic acid. There were no significant differences in mean percent change between baseline and day 28 for any of the eicosanoids, when normalized to protein. There was a significant decrease in mean percent change in PGE(2) (P = 0.05) and 5-HETE (P = 0.04), and a trend toward significant decreases in 12-HETE (P = 0.09) and 15-HETE (P = 0.06) normalized to free arachidonic acid. There was no difference between the groups in terms of total adverse events P = 0.55). On the basis of these results, it seems that ginger has the potential to decrease eicosanoid levels, perhaps by inhibiting their synthesis from arachidonic acid. Ginger also seemed to be tolerable and safe. Further investigation in people at high risk for CRC seems warranted.

Identification of a novel class of anti-inflammatory compounds with anti-tumor activity in colorectal and lung cancers

Chronic inflammation is associated with 25% of all cancers. In the inflammation-cancer axis, prostaglandin E(2) (PGE(2)) is one of the major players. PGE(2) synthases (PGES) are the enzymes downstream of the cyclooxygenases (COXs) in the PGE(2) biosynthesis pathway. Microsomal prostaglandin E(2) synthase 1 (mPGES-1) is inducible by pro-inflammatory stimuli and constitutively expressed in a variety of cancers. The potential role for this enzyme in tumorigenesis has been reported and mPGES-1 represents a novel therapeutic target for cancers. In order to identify novel small molecule inhibitors of mPGES-1, we screened the ChemBridge library and identified 13 compounds as potential hits. These compounds were tested for their ability to bind directly to the enzyme using surface plasmon resonance spectroscopy and to decrease cytokine-stimulated PGE(2) production in various cancer cell lines. We demonstrate that the compound PGE0001 (ChemBridge ID number 5654455) binds to human mPGES-1 recombinant protein with good affinity (K(D) = 21.3 ± 7.8 μM). PGE0001 reduces IL-1β-induced PGE(2) release in human HCA-7 colon and A549 lung cancer cell lines with EC(50) in the sub-micromolar range. Although PGE0001 may have alternative targets based on the results from in vitro assays, it shows promising effects in vivo. PGE0001 exhibits significant anti-tumor activity in SW837 rectum and A549 lung cancer xenografts in SCID mice. Single injection i.p. of PGE0001 at 100 mg/kg decreases serum PGE(2) levels in mice within 5 h. In summary, our data suggest that the identified compound PGE0001 exerts anti-tumor activity via the inhibition of the PGE(2) synthesis pathway.

Prognostic significance of cytosolic phospholipase A2 expression in patients with colorectal cancer

PURPOSE

Cyclooxygenase-2 is believed to be an important enzyme in the pathogenesis of colorectal cancer (CRC). Cytosolic phospholipase A2 (cPLA2), also, have been suggested to be related to the carcinogenesis of CRC. The aim of this study was to investigate cPLA2 expression and its relationship with prognostic significance in CRC.

METHODS

Eighty-eight patients with colorectal cancer who underwent curative surgery were enrolled in this study. cPLA2 was examined in 88 primary CRCs by immunohistochemistry and we compared their expression with clinicopathologic findings, recurrence and survival in patients with CRC.

RESULTS

The expression of cPLA2 was positive in 54.5% (48/88). The expression of cPLA2 was not correlated with clinicopathologic parameters. However, cPLA2 expression was significantly related with vascular endothelial growth factor expression. Kaplan-Meier analysis didn't show any clinical significance in disease-free survival and overall survival according to cPLA2 expression.

CONCLUSION

These results suggest that cPLA2 expression was not associated with the prognosis of CRC. However, further large-scale studies are needed to clarify the prognostic effect of cPLA2 in CRC.

Gender-specific genomic profiling in metastatic colorectal cancer patients treated with 5-fluorouracil and oxaliplatin

AIMS

Survival and response rates in metastatic colorectal cancer remain poor, despite advances in drug development. There is increasing evidence to suggest that gender-specific differences may contribute to poor clinical outcome. We tested the hypothesis that genomic profiling of metastatic colorectal cancer is dependent on gender.

MATERIALS & METHODS

A total of 152 patients with metastatic colorectal cancer who were treated with oxaliplatin and continuous infusion 5-fluorouracil were genotyped for 21 polymorphisms in 13 cancer-related genes by PCR. Classification and regression tree analysis tested for gender-related association of polymorphisms with overall survival, progression-free survival and tumor response.

RESULTS

Classification and regression tree analysis of all polymorphisms, age and race resulted in gender-specific predictors of overall survival, progression-free survival and tumor response. Polymorphisms in the following genes were associated with gender-specific clinical outcome: estrogen receptor β, EGF receptor, xeroderma pigmentosum group D, voltage-gated sodium channel and phospholipase A2.

CONCLUSION

Genetic profiling to predict the clinical outcome of patients with metastatic colorectal cancer may depend on gender.