Search

After birth, the development of secondary lymphoid tissues (SLTs) in the colon is dependent on the expression of the aryl hydrocarbon receptor (AhR) in immune cells as a response to the availability of AhR ligands. However, little is known about how AhR activity from intestinal epithelial cells (IECs) may influence the development of tertiary lymphoid tissues (TLTs). As organized structures that develop at sites of inflammation or infection during adulthood, TLTs serve as localized centers of adaptive immune responses, and their presence has been associated with the resolution of inflammation and tumorigenesis in the colon. Here, we investigated the effect of the conditional loss of AhR activity in IECs in the formation and immune cell composition of TLTs in a model of acute inflammation. In females, loss of AhR activity in IECs reduced the formation of TLTs without significantly changing disease outcomes or immune cell composition within TLTs. In males lacking AhR expression in IECs, increased disease activity index, lower expression of functional-IEC genes, increased number of TLTs, increased T-cell density, and lower B- to Tcell ratio were observed. These findings may represent an unfavorable prognosis when exposed to dextran sodium sulfate (DSS)-induced epithelial damage compared with females. Sex and loss of IEC AhR also resulted in changes in microbial populations in the gut. Collectively, these data suggest that the formation of TLTs in the colon is influenced by sex and AhR expression in IECs. NEW & NOTEWORTHY This is the first research of its kind to demonstrate a clear connection between biological sex and the development of tertiary lymphoid tissues (TLT) in the colon. In addition, the research finds that in a preclinical model of inflammatory bowel disease, the expression of the aryl hydrocarbon receptor (AhR) influences the development of these structures in a sex-specific manner [ABSTRACT FROM AUTHOR]

A series of experiments was conducted to investigate the mutagenic potential of binary and complex mixtures in the presence and absence of inducible liver enzyme systems prepared with several different chemical inducers. Liver homogenate (S9, or 9000 g supernatant) fractions were obtained from Sprague-Dawley rats induced with either Aroclor 1254 (AR), phenobarbital (PB), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), or corn oil (UI). The mutagenic potential of test samples was m easured with Salmonella typhimurium strain TA98 using each of the various S9 fractions. Test samples included benzo[a]pyrene (BaP), pentachlorophenol (PCP), a binary mixture of BaP and PCP, two five-component mixtures, a methylene chloride extract of wood preserving waste-amended soil, and a methanol extract of coal gasification waste. At a dose of 25 mu g/plate, BaP produced 55, 83, 217, and 161 net revertants per plate with UI-, PB-, AR-, and TCDD-induced S9, respectively. The complex mixture extracted from the wood preserving waste-amended soil induced approximately equal responses with all four S9 mixes. At a dose of 250 mu g/plate, the methanol extract of a coal gasification waste produced 56 net revertants using the uninduced S9; however, when AR-and TCDD-induced S9 was used, 129 and 67 net revertants were observed, respectively. These data demonstrate the relative im portance of the various induced cytochrome P-450 isozymes for the metabolism of mutagenic chemicals and complex mixtures. [ABSTRACT FROM AUTHOR]

HOTAIR is a long intervening non-coding RNA (lincRNA) that associates with the Polycomb Repressive Complex 2 (PRC2) and overexpression is correlated with poor survival for breast, colon and liver cancer patients. In this study, we show that HOTAIR expression is increased in pancreatic tumors compared with non-tumor tissue and is associated with more aggressive tumors. Knockdown of HOTAIR (siHOTAIR) by RNA interference shows that HOTAIR has an important role in pancreatic cancer cell invasion, as reported in other cancer cell lines. In contrast, HOTAIR knockdown in Panc1 and L3.6pL pancreatic cancer cells that overexpress this lincRNA decreased cell proliferation, altered cell cycle progression and induced apoptosis, demonstrating an expanded function of HOTAIR in pancreatic cancer cells compared with other cancer cell lines. Results of gene array studies showed that there was minimal overlap between HOTAIR-regulated genes in pancreatic cells and breast cancer cells, and HOTAIR uniquely suppressed several interferon-related genes and gene sets related to cell cycle progression in pancreatic cancer cells and tumors. Analysis of selected genes suppressed by HOTAIR in Panc1 and L3.6pL cells showed by knockdown of EZH2 and chromatin immunoprecipitation assays that HOTAIR-mediated gene repression was both PRC2-dependent and -independent. HOTAIR knockdown in L3.6pL cells inhibited tumor growth in mouse xenograft model, further demonstrating the pro-oncogenic function of HOTAIR in pancreatic cancer. [ABSTRACT FROM AUTHOR]

The orphan nuclear receptor TR3 (NR41A and Nur77) is overexpressed in most lung cancer patients and is a negative prognostic factor for patient survival. The function of TR3 was investigated in non-small-cell lung cancer A549 and H460 cells, and knockdown of TR3 by RNA interference (siTR3) inhibited cancer cell growth and induced apoptosis. The prosurvival activity of TR3 was due, in part, to formation of a p300/TR3/ specificity protein 1 complex bound to GC-rich promoter regions of survivin and other Sp-regulated genes (mechanism 1). However, in p53 wild-type A549 and H460 cells, siTR3 inhibited the mTORC1 pathway, and this was due to activation of p53 and induction of the p53-responsive gene sestrin 2, which subsequently activated the mTORC1 inhibitor AMP-activated protein kinase α (AMPKα) (mechanism 2). This demonstrates that the pro-oncogenic activity of TR3 in lung cancer cells was due to inhibition of p53 and activation of mTORC1. 1,1-Bis(3'-indolyl)-1-(p-hydroxyphenyl)methane (DIM-C-pPhOH) is a recently discovered inhibitor of TR3, which mimics the effects of siTR3. DIM-C-pPhOH inhibited growth and induced apoptosis in lung cancer cells and lung tumors in murine orthotopic and metastatic models, and this was accompanied by decreased expression of survivin and inhibition of mTORC1 signaling, demonstrating that inactivators of TR3 represent a novel class of mTORC1 inhibitors. [ABSTRACT FROM AUTHOR]

Background Tolfenamic acid ( TA) is an NSAID currently under investigation as an anticancer agent in humans. TA induces proteosome-dependent degradation of transcription factors Sp 1, 3, and 4. These proteins are known to be overexpressed in many human cancers. Hypothesis To evaluate the protein expression of Sps in canine tissue, and efficacy of TA against several canine tumor cell lines. Methods Six canine cell lines (2 osteosarcoma, 2 mammary carcinoma, 2 melanoma) were evaluated. Protein levels of Sp 1-4 and their downstream targets were evaluated using Western Blots. Cell survival and TUNEL assays were performed on cell lines, and Sp1 expression was evaluated on histologic samples from archived canine cases. Animals Six immortalized canine cancer cell lines derived from dogs were used. Archived tissue samples were also used. Results Sps were highly expressed in all 6 cell lines and variably expressed in histologic tissues. TA decreased expression of Sps 1-4 in all cell lines. All of the downstream targets of Sps were inhibited in the cell lines. Variable Sp1 expression was identified in all histologic samples examined. TA significantly inhibited cell survival in all cell lines in a dose dependant fashion. The number of cells undergoing apoptosis was significantly increased ( P < .05) in all cell lines after exposure to TA in a dose-dependent fashion. Conclusions, and Clinical Importance Tolfenamic acid is a potential anticancer NSAID and further investigation is needed to determine its usefulness in a clinical setting. [ABSTRACT FROM AUTHOR]

BACKGROUND: Macrophage activation plays a crucial role in regulating adipose tissue inflammation and is a major contributor to the pathogenesis of obesity-associated cardiovascular diseases. On various types of stimuli, macrophages respond with either classic (M1) or alternative (M2) activation. M1- and M2-mediated signaling pathways and corresponding cytokine production profiles are not completely understood. The discovery of microRNAs provides a new opportunity to understand this complicated but crucial network for macrophage activation and adipose tissue function. METHODS AND RESULTS: We have examined the activity of microRNA-223 (miR-223) and its role in controlling macrophage functions in adipose tissue inflammation and systemic insulin resistance. miR-223(-/-) mice on a high-fat diet exhibited an increased severity of systemic insulin resistance compared with wild-type mice that was accompanied by a marked increase in adipose tissue inflammation. The specific regulatory effects of miR-223 in myeloid cell-mediated regulation of adipose tissue inflammation and insulin resistance were then confirmed by transplantation analysis. Moreover, using bone marrow-derived macrophages, we demonstrated that miR-223 is a novel regulator of macrophage polarization, which suppresses classic proinflammatory pathways and enhances the alternative antiinflammatory responses. In addition, we identified Pknox1 as a genuine miR-223 target gene and an essential regulator for macrophage polarization. CONCLUSION: For the first time, this study demonstrates that miR-223 acts to inhibit Pknox1, suppressing proinflammatory activation of macrophages; thus, it is a crucial regulator of macrophage polarization and protects against diet-induced adipose tissue inflammatory response and systemic insulin resistance. [ABSTRACT FROM AUTHOR]

The human POK family members are transcription factors with a POZ domain and zinc-fingers that act primarily as transcriptional repressors. Several members of this family are involved in oncogenesis and this prompted us to assess whether expression levels of individual POK family members are associated with clinical outcomes in cancer. We have observed that ZBTB4 (zinc-finger and BTB domain containing 4) is downregulated in breast cancer patients, and that its expression is significantly correlated with relapse-free survival. Further integrative analysis of mRNA and microRNA (miR) expression data from the NCI-60 cell lines revealed an inverse correlation between ZBTB4 and oncogenic miRs derived from the miR-17-92 cluster and its paralogs. The experimental results using MDA-MB-231 and MCF-7 human breast cancer cells confirm that miRNAs derived from these clusters, containing miR-17-5p, miR-20a, miR-106a, miR-106b and miR-93, negatively regulate ZBTB4 expression. Overexpression of ZBTB4 or restoration of ZBTB4 by using an antagomir inhibit growth and invasion of breast cancer cells, and this effect is due, in part, to ZBTB4-dependent repression of the specificity protein 1 (Sp1), Sp3 and Sp4 genes, and subsequent downregulation of several Sp-dependent oncogenes, in part, through competition between ZBTB4 and Sp transcription factors for GC-rich promoter sequences. These results confirm that ZBTB4 functions as a novel tumor-suppressor gene with prognostic significance for breast cancer survival, and the oncogenic miR-17-92/ZBTB4/Sp axis may be a potential therapeutic target. [ABSTRACT FROM AUTHOR]

Purpose: 1,1-Bis(3-indolyl)-1-(p-substituted phenyl)methanes (C-DIMs) substituted in the phenyl ring with a para-, t-butyl, trifluoromethyl (DIM-C-pPhCF(3)) or phenyl (DIM-C-pPhC(6)H(5)) group activate peroxisome proliferator-activated receptor gamma (PPARgamma) in several cancer cell lines, and DIM-C-pPhCF(3) also activates the orphan receptor Nur77. In this study, we have examined the effects of 5,5'-dihydroxy, 5,5'-dimethyl, 5,5'-dibromo, 5,5'-dinitro and 5,5'-dimethoxyindole ring-substituted analogs of DIM-C-pPhC(6)H(5) on their activity as PPARgamma agonists.Methods: Various substituted C-DIM analogs were used to investigate their growth-inhibitory activities and activation of PPARgamma-mediated transactivation in colon and pancreatic cancer cells. Their structure-dependent induction of putative PPARgamma-responsive genes/proteins including p21, KLF-4 and caveolin1 were also determined by Western and Northern blot analysis.Results: Introduction of the 5,5'-dihydroxy and 5,5'-dimethyl substituents enhanced activation of PPARgamma in colon and pancreatic cancer cells. However, activation of p21 in Panc28 pancreatic cancer cells and induction of caveolin-1 and KLF4 in colon cancer cells by the C-DIM compounds were structure- and cell context-dependent.Conclusions: The results demonstrate that DIM-C-pPhC(6)H(5) and indole ring-substituted analogs are selective PPARgamma modulators. [ABSTRACT FROM AUTHOR]

Polyphenols from fruits and vegetables showed anti-cancer properties both in vitro and in vivo. Specialty (colored) potatoes are laden with polyphenols, and thus a potential route for uptake of these compounds by humans due to high consumption of this vegetable. In this study, we investigated mechanism of action for anti-proliferative and pro-apoptotic effects of potato extract and its fractions on LNCaP (androgen-dependent) and PC3 (androgen-independent) prostate cancer cells. We measured growth inhibition (WST; FACS), apoptosis (TUNEL) and Endo G, AIF, p-c-jun, and p-ERK (Westerns). Potato extract (PE) and the anthocyanin fraction (AF) at 5 µg chlorogenic acid eq/ml inhibited growth of LNCaP and PC3 cells, however, G0/G-S phase progression was inhibited only in LNCaP cells. PE and AF resulted in caspase-dependent apoptosis in LNCaP cells. PE and AF induced phosphorylation of kinases (c-jun and ERK) and nuclear translocation of Endo G and AIF (caspase-independent apoptotic proteins) in both LNCaP and PC3 cells. Kinase inhibitors reversed this nuclear translocation. This is the first report showing that the pro-apoptotic activities of PE/AF in cancer cells were due to activation of caspase-independent apoptosis. Current studies are focused on development of potato cultivars with increased levels of polyphenols with potential anticancer activities. [ABSTRACT FROM AUTHOR]

Background: Indole-3-carbinol (I3C) and related compounds have been identified in vegetables of the Brassica genus. I3C and its acid-derived condensation product, indolo[3,2-b]carbazole (ICZ), bind to the aryl hydrocarbon (Ah) receptor and induce CYP1A1/1A2 gene expression in both in vivo and in vitro models. I3C also inhibits mammary tumor development in rodent models.Purpose: The major focus of this study was to investigate the induction of CYP1A1-dependent activity and antiestrogenic effects of ICZ in the MCF-7 human breast cancer cell line and determine if induction of CYP1A1 is required for observed antiestrogenic responses.Methods: The induction of CYP1A1 in MCF-7 cells was determined by measuring time- and concentration-dependent changes in ethoxyresorufin O-deethylase (EROD) activity in response to ICZ treatment. The effects of ICZ on occupied nuclear estrogen receptor (ER) levels and inhibition of estrogen (17 beta-estradiol [E2])-induced cell proliferation, [3H]thymidine uptake, secretion of the 52-kd protein, and nuclear progesterone receptor (PR) levels were also measured. Chloramphenicol acetyl transferase (CAT) activity was assayed in MCF-7 cells transiently transfected with an estrogen-responsive vit-CAT plasmid. Competitive binding to rat cytosolic ER was also examined.Results: ICZ (> or = 10 nM) induced CYP1A1 in MCF-7 human breast cancer cells. This compound also elicited a diverse spectrum of antiestrogenic responses, including inhibition of E2-induced cell proliferation, [3H]thymidine uptake, occupied nuclear PR binding, and CAT activity in cells transfected with the estrogen-responsive vit-CAT plasmid. In nuclear extracts from ICZ-treated cells, there was a decrease in ER levels and binding to an estrogen-responsive element in a gel shift assay. I3C also decreased nuclear ER binding in MCF-7 cells. ICZ bound with low affinity to the ER and exhibited weak estrogen-like activity.Conclusions: Like other Ah receptor agonists, ICZ is antiestrogenic in human breast cancer cells, and this activity is consistent with the inhibitory activity of I3C on mammary tumor formation in rodents. ICZ-induced antiestrogenic responses can be observed at times or concentrations in which EROD activity is unchanged, indicating an interaction between the Ah receptor and ER-mediated endocrine pathways that is independent of P450-induced hormone metabolism. ICZ also is a weak estrogen in MCF-7 cells and binds to the ER.Implications: The current focus on the role of dietary and environmental estrogens in human disease should take into account the possible contra-active effects of Ah receptor agonists such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), ICZ, I3C, and related compounds that exhibit antiestrogenic activity. [ABSTRACT FROM AUTHOR]

The influences of in vivo pretreatment with phenobarbitone (PB), 3‐methylcholanthrene (3‐MC), 2,2’,4,4’,5,5'‐hexachlorobiphenyl (HCBP), and 3,3’,4,4'‐tetrachlorobiphenyl (TCBP) on cytocidal hepatotoxicity of two pyrrolizidine alkaloids, lasiocarpine (LC) and senecionine (SC), were compared in short‐term primary cultures of rat hepatocytes. Toxicity was measured by release of lactate dehydrogenase (LDH) into culture medium at 24 h. LC was slightly more toxic to control hepatocytes than SC in the graded response range of 10–160 μM. PB and HCBP (a PB‐type polychlorobiphenyl inducer) similarly potentiated toxicity of SC, and each diminished the degree to which cell killing by LC and SC was inhibited by SKF‐525‐A. By comparison, 3‐MC and TCBP (a 3‐MC‐type PCB inducer) each diminished toxicity of SC but had little effect on toxicity of LC. Alpha‐naphthoflavone (ANF) potentiated toxicity of both LC and SC in hepatocytes induced by 3‐MC or TCBP but had little effect on responses of hepatocytes induced by either PB or HDBP. These results indicate that xenobiotics that induce similar patterns of cytochrome P‐450 isozymes have qualitatively similar modulating influences on cytocidal hepatotoxicity of pyrrolizidine alkaloids in primary cultures. However, the observed modulating effects could not be explained solely on the basis of altered activation rates by the cytochrome P‐450 species known to be induced by the various xenobiotics. [ABSTRACT FROM PUBLISHER]

The Galveston Bay estuary exhibited a contamination gradient for polynuclear aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons, and the comparative sensitivity of various biomarkers in fishfrom different bay locations were determined. Two fish species, hardhead catfish (Arius felis) and Atlantic croaker (Micropogon undulatus), were collected from four stations where sediment total PAHs rangedfrom 68 to >1,000 ng/g. The induction of cytochrome P4501A-(CYP1A-) dependent hepatic ethoxyresorufin-O-deethylase (EROD) activity, CYP1AmRNA levels, or CYP1A immunoreactive protein in hardhead catfish washighly variable in the field-collected fish and in fish dosed with up to 15 mg/kg benzo[a]pyrene (BaP). In contrast, significant differences were seen in biliary concentrations of naphthalene, phenanthrene,and BaP metabolites in hardhead catfish from polluted versus less polluted areas. In croakers taken from the same four Galveston Bay, locations, EROD and glutathione S-transferase activities, immunoreactiveCYP1A protein, biliary PAH metabolites, and PAH-DNA adducts were higher at the contaminated stations compared with less polluted locations. These studies suggest that the croaker is a good species for monitoring contaminants that induce CYP1A- mediated responses. Biliary PAHmetabolites and PAH-DNA adducts were also sensitive indicators of exposure to PAH contamination in both species of fish. [ABSTRACT FROM AUTHOR]