Anti-tumorigenic Properties Research Articles

Abstract 2035: Activating transcription factor 2 (ATF2) controls tolfenamic acid-induced ATF3 expression via MAP kinase pathways

Abstract Tolfenamic acid (TA) is a non-steroidal anti-inflammatory drug associated with anti-tumorigenic and pro-apoptotic properties in animal and in vitro models of cancer. However, the underlying cellular mechanisms by which TA exerts its effects are only partially understood. Activating transcription factor 3 (ATF3) is a member of the ATF/CREB subfamily of the basic region-leucine zipper family and has been known as a tumor suppressor in human colorectal cancer cells. The present study was performed to observe whether ATF3 mediates TA-induced apoptosis and to elucidate the molecular mechanism of ATF3 transcription induced by TA. TA treatment and ectopic expression of ATF3 increased apoptosis whereas knockdown of ATF3 resulted in significant repression of TA-activated apoptosis. The TA treatment also induced ATF3 promoter activity. Internal deletion and point mutation of the predicted ATF/C/EBP binding site in ATF3 promoter abolished luciferase activation by TA. Overexpression of ATF2 resulted in significant increase of ATF3 promoter activity, and electrophoretic mobility shift assay identified this region as a core sequence to which ATF2 binds. TA treatment resulted in an increase of ATF2 phosphorylation, which was followed by a subsequent increase of ATF3 transcription. Knockdown of ATF2 abolished TA-induced ATF3 expression. We further provide evidence that TA leads to increases of phospho-p38 MAPK, JNK, and ERK levels. Inhibition of these pathways using selective inhibitors and dominant negative constructs ameliorated TA-induced ATF3 expression and promoter activities. The current study demonstrates that TA stimulates ATF3 expression and subsequently induces apoptosis. These pathways are mediated through phosphorylation of ATF2, which is mediated by p38 MAPK, JNK, and ERK-dependent pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2035. doi:10.1158/1538-7445.AM2011-2035

Abstract 3507: Sulforaphane facilitates mitotic cell death triggered by arsenic trioxide

Abstract Arsenic trioxide (ATO) is an important antileukemic drug, but its use as a single agent in clinical trials against solid tumors was found to be mostly not effective or too toxic. Given the toxicity of chemotherapeutic agents, there is a considerable interest in the use of natural compounds with anti-tumorigenic properties for cancer treatment. In this study, we demonstrate that the cytotoxicity of ATO is significantly increased by cotreatment with non-toxic concentration of sulforaphane, an isothiocyanate found in cruciferous vegetables. The increased cytotoxicity was preceded by enhanced generation of reactive oxygen species and ATO-induced mitotic abnormalities and mitotic arrest. Consequently, sulforaphane facilitated mitotic cell death caused by ATO. However, neither zVADfmk (a pan caspase inhibitor) nor necrostatin (a necrosis inhibitor) prevented the cell death induced by the combined treatment indicating that caspase-dependent apoptosis or nercrosis is not involved in the enhanced cytotoxicity. In addition, no significant change on NF-κB-dependent transcription was observed at the non-toxic concentration used in this study indicating that sulforaphane did not exert the enhanced killing effect by inhibition of NF-κB. Since induction of mitotic arrest and mitotic cell death selectively kills highly proliferating cells, the enhanced mitotic cell death induced by cotreatment of ATO and sulforaphane provides a strategy to selectively kill cancer cells and to enhance the therapeutic efficacy of ATO. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3507. doi:10.1158/1538-7445.AM2011-3507

Abstract 2407: Decreased inflammation and tumor stage in COX-2 knockout mice in the BBN model of bladder cancer

Abstract Introduction and Objective: Prostaglandins (PG) play a critical role in the development of solid tumors. Inhibition of cyclooxygenase-2 (COX-2), the committed step in PG synthesis, has been shown to impair tumor development in the BBN mouse model of bladder cancer. Because inhibitors of COX-2 have been reported to have anti-tumorigenic properties independent of COX-2, we evaluated the impact of gene disruption of COX-2 in the BBN mouse model. Methods: We used 2 mo old male COX-2 knockout (KO) and wild type (WT) mice in an outbred CD-1 background. Mice were treated with (n=13-14 / group) and without (n=6/group) BBN in drinking water and euthanized after 25-27 wks. Bladders were harvested, weighed, bisected and step sectioned after formalin fixation. H&E stained sections were evaluated for pathologic stage/grade, percent involvement by invasive disease and degree of inflammatory infiltrate(grade 1-3). Results: All animals receiving BBN had inflammatory changes at the time of euthanasia, with the grade being higher in WT (grade 2-3) than KO mice (grade 1-2). Six WT mice and 3 KO mice receiving BBN died, all within the first 18 wks of study, without gross evidence of tumor. Compared to previous studies with C57Bl/6 mice, tumor development was slower and burden was lower at 25-27 wks. All 7 BBN-treated WT mice had high grade invasive cancer at euthanasia: 6 pT1 and 1 pT3. Out of 11 BBN-treated KO mice at euthanasia, 10 had high grade cancer and 2 had invasive disease: 1 pT0, 6 CIS, 2 pTa (non-invasive) and 2 pT1. Mean bladder weight at euthanasia was elevated only in BBN-treated WT mice. There was a strong correlation between WT genotype and tumor stage by Pearson's R (0.74, p=0.03). The percent of tumor representing invasive disease was 0.31 in COX-2 WT mice vs 0.01 in KO mice (t-test, p=0.002). Conclusions: Genetic disruption of COX-2 resulted in lower tumor stage and percent invasiveness in the BBN mouse model of bladder cancer. However, most COX-2 KO mice developed high grade disease, indicating disruption of COX-2 was not sufficient to prevent tumorigenesis. Reduced inflammation in the COX-2 KO mice may account for the decreased invasiveness. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2407. doi:10.1158/1538-7445.AM2011-2407

Potential implications of mesenchymal stem cells in cancer therapy

Mesenchymal stem cells (MSCs) are the first type of stem cells to be utilized in clinical regenerative medicine, mainly owing to their capacity for multipotent differentiation and the feasibility of autologous transplantation. More recently, the specific tumor-oriented migration and incorporation of MSCs have been demonstrated in various pre-clinical models, highlighting the potential for MSCs to be used as an ideal carrier for anticancer gene delivery. Engineered with specific anticancer genes, MSCs possess the ability of dual-targeting tumor cells. This contrasts with non-engineered native MSCs which have intrinsic pro- and anti-tumorigenic properties. Engineered MSCs are capable of producing specific anticancer agents locally and constantly. Astute investigation on engineered MSCs may lead to a new avenue toward an efficient therapy for patients with cancer.

Liver Transplantation for Massive Hepatic Lymphangiomatosis in a Child

Liver Transplantation for Massive Hepatic Lymphangiomatosis in a Child

Chemoprevention with Aqueous Extract of Butea monosperma flowers results in normalization of nuclear morphometry and inhibition of a proliferation marker in liver tumors

Butea monosperma (Lam.) (family: Fabaceae) popularly known as 'Palas' or 'fire of forest' has been used traditionally as a hepatoprotective agent. This study evaluated the hepatoprotective and antitumorigenic properties of the aqueous extract and butanol fractions of B. monosperma flowers in animal models. Dried flowers of B. monosperma were extracted with water and fractionated further using n-butanol. The hepatoprotective activity of the aqueous extract was initially confirmed in a carbon tetrachloride-induced liver damage model of rats. Oral administration of the aqueous extract produced a strong hepatoprotective effect similar to silymarin and normalized the serum levels of ALT, AST, bilirubin and triglyceride in rats. However, it did not affect the levels of glutathione and malondialdehyde which are oxidative stress markers in liver. Intraperitoneal administration of the aqueous extract in the X15-myc oncomice not only maintained liver architecture and nuclear morphometry but also down-regulated the serum VEGF levels. Immunohistochemical staining of liver sections with anti-Ribosomal protein S27a antibody showed post-treatment abolition of this proliferation marker from the tumor tissue. The butanol fractions, however, did not show antitumorigenic activity. Thus, the aqueous extract of B. monosperma flowers is not only hepatoprotective but also antitumorigenic by preserving the nuclear morphometry of the liver.

In vitro tissue culture of the medicinal shrub Calotropis procera to produce pharmacologically active proteins from plant latex

The latex of Calotropis procera is a rich source of proteins that have anti-inflammatory, anti-nociceptive and selective cytotoxic and anti-tumorigenic properties. In this study, two distinct protocols were developed to culture C. procera in vitro in order to obtain active molecules. Soluble proteins of both callus and root cultures were extracted and tested for various activities found in the latex. Anti-inflammatory and anti-nociceptive proteins were present in callus and root extracts; however, these proteins did not possess cytotoxic or anti-tumorigenic activity. Larvicidal proteins were present, but they were not related to others that have been reported previously in latex. This study confirms that tissue culture of C. procera is able to produce therapeutic-grade proteins that have the potential to relieve inflammation and pain associated with inflammatory disorders.

Use of 1,25α dihydroxyvitamin D3 as a cryosensitizing agent in a murine prostate cancer model

Cryotherapy has emerged as a primary treatment option for prostate cancer(CaP); however, incomplete ablation in the periphery of the cryogenic lesion can lead to recurrence. Accordingly, we investigated the use of a nontoxic adjunctive agent, Vitamin D3, with cryotherapy to sensitize CaP to low temperature induced, non-ice rupture related cell death. Vitamin D3 (calcitriol) has been identified as a possible adjunct in the treatment of cancer due to its anti-proliferative and anti-tumorigenic properties. This study aimed to identify the cellular responses and molecular pathways activated when vitamin D3 (calcitriol) is combined with cryotherapy in a murine prostate cancer model. Single freeze-thaw events above −15°C had little effect on cancer cell viability; however, pre-treatment with calcitriol in conjunction with cryo significantly increased cell death. The −15°C calcitriol combination increased cell death to 55% following a single freeze, compared to negligible cell loss by freezing or calcitriol alone. Repeat cryo-combination yielded90% cell death, compared to 65% in dual freeze-only cycles. Western blot analysis following calcitriol cryosensitization regimes confirmed the activation of apoptosis. Specifically, pro-apoptotic Bid and pro-caspase–3 were found to decrease at 1h following combination treatment, indicating cleavage to the active forms. A parallel in vivo study confirmed the increased cell death when combining cryotherapy with calcitriol pre-treatment. The development of an adjunctive therapy combining calcitriol and cryotherapy represents a potentially highly effective, less toxic, minimally invasive treatment option. These results suggest a role for calcitriol and cryo as a combinatorial treatment for CaP with the potential for clinical translation.

Diverse animal models to examine potential role(s) and mechanism of endocrine disrupting chemicals on the tumor progression and prevention: Do they have tumorigenic or anti-tumorigenic property?

Acting as hormone mimics or antagonists in the interaction with hormone receptors, endocrine disrupting chemicals (EDCs) have the potentials of disturbing the endocrine system in sex steroid hormone-controlled organs and tissues. These effects may lead to the disruption of major regulatory mechanisms, the onset of developmental disorders, and carcinogenesis. Especially, among diverse EDCs, xenoestrogens such as bisphenol A, dioxins, and di(2-ethylhexyl)phthalate, have been shown to activate estrogen receptors (ERs) and to modulate cellular functions induced by ERs. Furthermore, they appear to be closely related with carcinogenicity in estrogen-dependant cancers, including breast, ovary, and prostate cancers. In in vivo animal models, prenatal exposure to xenoestrogens changed the development of the mouse reproductive organs and increased the susceptibility to further carcinogenic exposure and tumor occurence in adults. Unlike EDCs, which are chemically synthesized, several phytoestrogens such as genistein and resveratrol showed chemopreventive effects on specific cancers by contending with ER binding and regulating normal ER action in target tissues of mice. These results support the notion that a diet containing high levels of phytoestrogens can have protective effects on estrogen-related diseases. In spite of the diverse evidences of EDCs and phytoestrogens on causation and prevention of estrogen-dependant cancers provided in this article, there are still disputable questions about the dose-response effect of EDCs or chemopreventive potentials of phytoestrogens. As a wide range of EDCs including phytoestrogens have been remarkably increasing in the environment with the rapid growth in our industrial society and more closely affecting human and wildlife, the potential risks of EDCs in endocrine disruption and carcinogenesis are important issues and needed to be verified in detail.

Estrogens from the Outside In: Alkylphenols, BPA Disrupt ERK Signaling in Vitro

Vol. 119, No. 1 NewsOpen AccessEstrogens from the Outside In: Alkylphenols, BPA Disrupt ERK Signaling in Vitro Julia R. Barrett Julia R. Barrett Search for more papers by this author Published:1 January 2011https://doi.org/10.1289/ehp.119-a34bCited by:1AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit The body produces estrogens—including estrone (E1), estradiol (E2), and estriol (E3)—that direct reproductive system processes and contribute to the normal function of tissues including the brain, bone, and cardiovascular system. Certain xenoestrogens (estrogenic compounds introduced from outside the body) are suspected of disrupting these activities. In a new study, xenoestrogenic alkylphenols and bisphenol A (BPA) interfered with normal estrogenic signaling in vitro, which suggests they could disrupt normal physiologic function at critical life stages [EHP119(1):104–112; Jeng and Watson].Different estrogen receptors control different functions: receptors in the cell nucleus direct gene transcription, whereas receptors in the cell membrane direct signaling pathways via extracellular signal–regulated kinases (ERKs). ERK-controlled pathways respond to many biochemical stimuli and integrate these signals to direct a cell toward division, differentiation, death, or malignant transformation. The structurally related alkylphenols and BPA interact weakly with nuclear estrogen receptors, but they can have pronounced effects on signaling pathways mediated by estrogen receptors in the cell membrane.In the current study, a rat pituitary cancer cell line was used to study the effect of alkylphenols and BPA on ERK1 and ERK2 activation (measured as phosphorylation), both alone and in combination with each physiologic estrogen. After treatment with each physiologic and environmental estrogen, the researchers measured time-dependent surges in ERK activation. In most cases, E1 and E2 prompted early, intermediate, and late surges in ERK activation at 5, 10–30, and >30 min, respectively; alkylphenols and E3 typically triggered early and late surges. Interestingly, a very low concentration of BPA (10−14 M) yielded a similar two-peak response, but a higher concentration (1 nM) induced a three-peak response like that of E1 and E2. Both BPA concentrations were typical of environmental exposures and, along with ineffective midrange doses, also illustrated the nonmonotonic dose–response relationship characteristic of many estrogenic compounds.When physiologic estrogens and xenoestrogens were combined, the response pattern generally shifted to a single major peak at an intermediate time. Xenoestrogens that caused a strong response when administered alone at a particular point in time or concentration tended to inhibit ERK activation in response to a physiologic estrogen. But at other times or concentrations, the same xenoestrogen might cause a weak response on its own, in which case it would tend to enhance ERK phosphorylation in response to physiologic estrogens.There were exceptions to these general patterns, however, which highlights the need to study effects of individual xenoestrogens at different points in time, at varying concentrations, and in different tissues. The effect of shifts in the patterns of ERK activation are only just beginning to be explored, although it is known that these patterns constitute an important component of information flow within a cell. The correct flow of information is likely to be especially critical during windows of vulnerability that are based in part on life stage.FiguresReferencesRelatedDetailsCited by Park M, Hwang K and Choi K (2011) Diverse animal models to examine potential role(s) and mechanism of endocrine disrupting chemicals on the tumor progression and prevention: Do they have tumorigenic or anti-tumorigenic property?, Laboratory Animal Research, 10.5625/lar.2011.27.4.265, 27:4, (265), . Vol. 119, No. 1 January 2011Metrics About Article Metrics Publication History Originally published1 January 2011Published in print1 January 2011 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Is there a role for carbohydrate restriction in the treatment and prevention of cancer?

Over the last years, evidence has accumulated suggesting that by systematically reducing the amount of dietary carbohydrates (CHOs) one could suppress, or at least delay, the emergence of cancer, and that proliferation of already existing tumor cells could be slowed down. This hypothesis is supported by the association between modern chronic diseases like the metabolic syndrome and the risk of developing or dying from cancer. CHOs or glucose, to which more complex carbohydrates are ultimately digested, can have direct and indirect effects on tumor cell proliferation: first, contrary to normal cells, most malignant cells depend on steady glucose availability in the blood for their energy and biomass generating demands and are not able to metabolize significant amounts of fatty acids or ketone bodies due to mitochondrial dysfunction. Second, high insulin and insulin-like growth factor (IGF)-1 levels resulting from chronic ingestion of CHO-rich Western diet meals, can directly promote tumor cell proliferation via the insulin/IGF1 signaling pathway. Third, ketone bodies that are elevated when insulin and blood glucose levels are low, have been found to negatively affect proliferation of different malignant cells in vitro or not to be usable by tumor cells for metabolic demands, and a multitude of mouse models have shown anti-tumorigenic properties of very low CHO ketogenic diets. In addition, many cancer patients exhibit an altered glucose metabolism characterized by insulin resistance and may profit from an increased protein and fat intake.In this review, we address the possible beneficial effects of low CHO diets on cancer prevention and treatment. Emphasis will be placed on the role of insulin and IGF1 signaling in tumorigenesis as well as altered dietary needs of cancer patients.

Resveratrol-Induced Apoptosis Is Mediated by Early Growth Response-1, Krüppel-Like Factor 4, and Activating Transcription Factor 3

Resveratrol, a dietary phytoalexin readily available in the diet, is reported to possess antitumorigenic properties in several cancers, including colorectal. However, the underlying mechanism(s) involved is not completely understood. In the present study, we investigated the effect of resveratrol treatment on gene modulation in human colorectal cancer cells and identified activating transcription factor 3 (ATF3) as the most highly induced gene after treatment. We confirmed that resveratrol upregulates ATF3 expression, both at the mRNA and protein level, and showed resveratrol involvement in ATF3 transcriptional regulation. Analysis of the ATF3 promoter revealed the importance of early growth response-1 (Egr-1; located at -245 to -236) and Krüppel-like factor 4 (KLF4; located at -178 to -174) putative binding sites in resveratrol-mediated ATF3 transactivation. Specificity of these sites to the Egr-1 and KLF4 protein was confirmed by electrophoretic mobility shift and chromatin immunoprecipitation assays. Resveratrol increased Egr-1 and KLF4 expression, which preceded ATF3 expression, and further suggests Egr-1 and KLF4 involvement in resveratrol-mediated activity. We provide evidence for Egr-1 and KLF4 interaction in the presence of resveratrol, which may facilitate ATF3 transcriptional regulation by this compound. Furthermore, we demonstrate that induction of apoptosis by resveratrol is mediated, in part, by increased ATF3 expression. Taken together, these results provide a novel mechanism by which resveratrol induces ATF3 expression and represent an additional explanation of how resveratrol exerts its antitumorigenic effects in human colorectal cancer cells.

Dietary administration of berberine or Phellodendron amurense extract inhibits cell cycle progression and lung tumorigenesis

Phellodendron amurense extract is a Chinese herbal remedy that has recently been studied for its antitumor, antimicrobial and other biological activities. It is previously unknown if these agents are bioavailable and effective against tumors when delivered as a dietary component. It is also unknown if the anti-tumorigenic properties of berberine, an isoquinoline alkaloid component of P. amurense, is equally effective when administered alone. There are contrasting reports on the cellular processes involved in anti-tumorigenesis by P. amurense and berberine. Here we find that berberine, when administered orally through the diet, inhibits in vivo tumorigenesis of both p53 expressing and p53 null lung tumor xenografts equally whether administered in its pure form or as a part of P. amurense extract. We also show that berberine induces G1 cell cycle arrest, inhibits proliferative kinase signaling and arrests the growth of lung tumor cells in culture. Berberine administered in the diet was detectable by HPLC in the lungs of mice fed P. amurense or equivalent doses of berberine at concentrations of 455 and 518 ng/ml respectively and inhibited the growth of xenografted A549 cell tumors, which grew to 9.4 and 6.4 mm³ respectively, compared to 58.9 mm³ in control mice (P < 0.001). Phosphorylation of Akt, CREB and MAPK was inhibited in A549 cells by P. amurense. Demonstration of oral bioavailability and anti-tumorigenic efficacy of dietary berberine, as well as further demonstration of signaling pathway modulation and cell-cycle arrest, implicate this relatively safe, natural compound as a potentially important therapeutic and chemopreventive agent for lung cancer.

Resveratrol enhances the sensitivity of cholangiocarcinoma to chemotherapeutic agents

Cholangiocarcinomas are devastating cancers that are resistant to chemotherapies. Resveratrol, a food-derived polyphenol with antitumorigenic properties, can regulate the expression of cytochrome p450 1b1 (Cyp1b1), which may confer chemoresistance in various cancers. Our aims were to assess the effects of resveratrol on the sensitivity of cholangiocarcinoma cells to chemotherapeutic agents and show an association between Cyp1b1 expression and chemosensitivity. Cholangiocarcinoma cell lines were treated with resveratrol before the addition of 5-fluorouracil (5-FU), gemcitabine, or mitomycin C. Cell proliferation and apoptosis were assessed by MTS assays and Annexin staining. Resveratrol effects on cholangiocarcinoma tumor sensitivity to 5-FU was assessed in an in vivo xenograft model using Mz-ChA-1 cells. After resveratrol treatment, Cyp1b1 expression was assessed by real-time PCR and immunoblotting. Stable-transfected cell lines with Cyp1b1 expression knocked down (Mz-Cyp1b1) were used to assess sensitivity to chemotherapeutic agents by MTS assays and Annexin staining and in a xenograft model using Mz-ChA-1 and Mz-Cyp1b1 cells, respectively. For each chemotherapeutic agent, co-treatment with resveratrol in vitro decreased cell proliferation and increased apoptosis to a greater extent than with the chemotherapeutic agent alone. In vivo, 5-FU+resveratrol decreased tumor size and increased TUNEL staining to a greater extent than 5-FU alone. In parallel, resveratrol decreased Cyp1b1 expression in Mz-ChA-1 cells and in cholangiocarcinoma tumors. Mz-Cyp1b1 cells were more sensitive to chemotherapeutic agents in vitro than mock-transfected cells, and Mz-Cyp1b1-induced tumors were more susceptible to 5-FU treatment. We suggest that resveratrol treatment may be a useful adjunct therapy to improve chemosensitivity in cholangiocarcinoma.

Brg-1 mediates the constitutive and fenretinide-induced expression of SPARC in mammary carcinoma cells via its interaction with transcription factor Sp1

BackgroundSecreted protein, acidic and rich in cysteine (SPARC) is a matricellular protein that mediates cell-matrix interactions. It has been shown, depending on the type of cancer, to possess either pro- or anti-tumorigenic properties. The transcriptional regulation of the SPARC gene expression has not been fully elucidated and the effects of anti-cancer drugs on this process have not been explored.ResultsIn the present study, we demonstrated that chromatin remodeling factor Brg-1 is recruited to the proximal SPARC promoter region (-130/-56) through an interaction with transcription factor Sp1. We identified Brg-1 as a critical regulator for the constitutive expression levels of SPARC mRNA and protein in mammary carcinoma cell lines and for SPARC secretion into culture media. Furthermore, we found that Brg-1 cooperates with Sp1 to enhance SPARC promoter activity. Interestingly, fenretinide [N-4(hydroxyphenyl) retinamide, 4-HPR], a synthetic retinoid with anti-cancer properties, was found to up-regulate the transcription, expression and secretion of SPARC via induction of the Brg-1 in a dose-dependent manner. Finally, our results demonstrated that fenretinide-induced expression of SPARC contributes significantly to a decreased invasion of mammary carcinoma cells.ConclusionsOverall, our results reveal a novel cooperative role of Brg-1 and Sp1 in mediating the constitutive and fenretinide-induced expression of SPARC, and provide new insights for the understanding of the anti-cancer effects of fenretinide.

Expression of Membrane Progesterone Receptors (mPR/PAQR) in Ovarian Cancer Cells: Implications for Progesterone-Induced Signaling Events

The high mortality rates associated with ovarian cancer are largely due to a lack of highly effective treatment options for advanced stage disease; a time when initial diagnosis most commonly occurs. Recent evidence suggests that the steroid hormone, progesterone, may possess anti-tumorigenic properties. With the discovery of a new class of membrane-bound progesterone receptors (mPRs) belonging to the progestin and adipoQ receptor (PAQR) gene family in the ovary, there are undefined mechanisms by which progesterone may inhibit tumor progression. Therefore, our goal was to define potential mPR-dependent signaling mechanisms operative in ovarian cancer cells. We detected abundant mPRα (PAQR7), mPRβ (PAQR8), and mPRγ (PAQR5), but not classical nuclear PR (A or B isoforms) mRNA expression and mPRα protein expression in a panel of commonly used ovarian cancer cell lines. In contrast to mPR action in breast cancer cells, progesterone alone failed to induce changes in cyclic adenosine monophosphate (cAMP) levels in ovarian cancer cells. However, progesterone enhanced cAMP production by β(1,2)-adrenergic receptors and increased isoproterenol-induced transcription from a cAMP response element (CRE)-driven reporter gene. Independently of β-adrenergic signaling, we additionally observed activation of both JNK1/2 and p38 MAPK in response to progesterone alone. This finding was supported by the results of a screen for potential mPR gene targets. Progesterone induced a significant increase in transcription of the pro-apoptotic marker BAX, whose activity and expression has been linked to JNK1/2 and p38 signaling. Inhibitors of JNK, but not p38, blocked progesterone-induced BAX expression. Taken together, these observations implicate at least two distinct signaling pathways that may be utilized by mPRs in ovarian cancer cells that exhibit regulatory genomic changes. These studies on mPR signaling in ovarian cancer lay the foundation for future work aimed at understanding how progesterone exerts its anti-tumorigenic effects in the ovary and suggest that pharmacologic activation of mPRs, abundantly expressed in ovarian cancers, may provide a new treatment option for patients with advanced stage disease.

Design of novel artemisinin-like derivatives with cytotoxic and anti-angiogenic properties

Artemisinins are plant products with a wide range of medicinal applications. Most prominently, artesunate is a well tolerated and effective drug for treating malaria, but is also active against several protozoal and schistosomal infections, and additionally exhibits anti-angiogenic, anti-tumorigenic and anti-viral properties. The array of activities of the artemisinins, and the recent emergence of malaria resistance to artesunate, prompted us to synthesize and evaluate several novel artemisinin-like derivatives. Sixteen distinct derivatives were therefore synthesized and the in vitro cytotoxic effects of each were tested with different cell lines. The in vivo anti-angiogenic properties were evaluated using a zebrafish embryo model. We herein report the identification of several novel artemisinin-like compounds that are easily synthesized, stable at room temperature, may overcome drug-resistance pathways and are more active in vitro and in vivo than the commonly used artesunate. These promising findings raise the hopes of identifying safer and more effective strategies to treat a range of infections and cancer.

Epigallocatechin-3-gallate activates Nrf2/HO-1 signaling pathway in cisplatin-induced nephrotoxicity in rats

Aims Cisplatin-induced nephrotoxicity is associated with increased oxidative stress and inflammatory cytokines in the kidney. Epigallocatechin-3-gallate (EGCG) has anti-oxidant, anti-inflammatory, and anti-tumorigenic properties. In this study, we investigated the effects of EGCG on cisplatin-induced nephrotoxicity and potential mechanisms by which it enhances antioxidant activities and resolves inflammation after EGCG treatment during cisplatin-induced nephrotoxicity. Main methods Twenty-eight rats were divided into four groups as control (group 1; no treatment; n = 7), EGCG (group 2; n = 7), cisplatin (group 3; n = 7) or cisplatin and EGCG (group 4; n = 7). After 2 days of EGCG treatment at a dose of l00 mg/kg BW, rats were treated with a single i.p. injection of cisplatin (7 mg/kg BW). On day 12 (10 days after the cisplatin treatment), all rats were sacrificed by cervical dislocation. The level of protein was examined by Western blotting. Key findings Cisplatin caused a significant decrease in the expression nuclear levels of NF-E2-related factor-2 (Nrf2), heme oxygenase-1(HO-1), and an increase in the levels of nuclear factor-kappa B (NF-κB p65) and 4-hydroxynonenal (HNE) an oxidative stress marker. EGCG supplementation significantly improved the changes associated with cisplatin nephrotoxicity by increasing levels of Nrf-2 and HO-1, and decreasing levels of NF-κB and HNE. Renal activities of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase) and glutathione were significantly lower in cisplatin-treated rats compared with control rats, and EGCG treatment significantly increased the activities of antioxidant enzymes and glutathione ( P < 0.001). Significance The results suggest that Nrf2/HO-1 signaling pathway may be the primary target for prevention of cisplatin-induced nephrotoxicity by EGCG, and that reduces it inflammation by inhibiting NF-κB.

Activating transcription factor 2 (ATF2) controls tolfenamic acid-induced ATF3 expression via MAP kinase pathways

Tolfenamic acid (TA) is a non-steroidal anti-inflammatory drug associated with anti-tumorigenic and pro-apoptotic properties in animal and in vitro models of cancer. However, the underlying cellular mechanisms by which TA exerts its effects are only partially understood. Activating transcription factor 3 (ATF3) is a member of the ATF/CREB subfamily of the basic region-leucine zipper family and has been known as a tumor suppressor in human colorectal cancer cells. The present study was performed to observe whether ATF3 mediates TA-induced apoptosis and to elucidate the molecular mechanism of ATF3 transcription induced by TA. TA treatment and ectopic expression of ATF3 increased apoptosis whereas knockdown of ATF3 resulted in significant repression of TA-activated apoptosis. The TA treatment also induced ATF3 promoter activity. Internal deletion and point mutation of the predicted ATF/C/EBP binding site in ATF3 promoter abolished luciferase activation by TA. Overexpression of ATF2 resulted in significant increase of ATF3 promoter activity, and electrophoretic mobility shift assay identified this region as a core sequence to which ATF2 binds. TA treatment resulted in an increase of ATF2 phosphorylation, which was followed by a subsequent increase of ATF3 transcription. Knockdown of ATF2 abolished TA-induced ATF3 expression. We further provide evidence that TA leads to increases of phospho-p38 MAPK, JNK, and ERK levels. Inhibition of these pathways using selective inhibitors and dominant negative constructs ameliorated TA-induced ATF3 expression and promoter activities. The current study demonstrates that TA stimulates ATF3 expression and subsequently induces apoptosis. These pathways are mediated through phosphorylation of ATF2, which is mediated by p38 MAPK, JNK, and ERK-dependent pathways.

Alternatively Activated Macrophage Possess Antitumor Cytotoxicity That Is Induced by IL-4 and Mediated by Arginase-1

Earlier studies have shown that the adoptive transfer of Th2-polarized CD4 T cells can clear established tumors from mice in an antigen-specific manner. Although eosinophils were implicated in this process, the exact mechanism of tumor clearance and which immune effector cells were involved, remain to be defined. Consequently, experiments were undertaken to elucidate the mechanism of Th2-mediated destruction of B16-F1 melanoma cells by examining the in vitro antitumor activity of leukocytes within a type-2 inflammatory infiltrate. The experimental data show that activation of alternatively activated macrophages (aaMacs) within type-2 infiltrates by IL-4 or IL-13 can inhibit B16-F1 melanoma cell proliferation through a mechanism that is dependent on arginase-1 depletion of L-arginine within the tumor cell microenvironment. Interestingly, whilst at higher E:T ratios aaMac exhibited antitumor activity, at lower E:T ratios aaMacs were observed to enhance rather than inhibit B16-F1 melanoma cell growth. This highlights the fine balance between stimulating the antitumorigenic and protumorigenic properties of aaMacs in tumor immunotherapy protocols.