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Background: Gastric cancer (GC) is a highly heterogeneous disease and remains one of the major causes of cancer-related mortality worldwide. The vast majority of GC cases are adenocarcinomas including diffuse and intestinal GC that may differ in their incidence between Asian and non-Asian cohorts. The intestinal-subtype GC has declined over the past 50 years. In contrast to the intestinal-subtype adenocarcinoma, the incidence of diffuse-subtype GC, often associated with poor overall survival, has constantly increased in the USA and Europe. The aim of this study was to analyze the expression and clinical significance of steroid hormone receptors, two membrane-bound receptors (ERRγ and GPER), and several genes involved in epigenetic alterations. The findings may contribute to revealing events driving tumorigenesis and may aid prognosis. Methods: Using mRNA from diffuse and intestinal GC tumor samples, the expression level of 11 genes, including those coding for sex hormone receptors (estrogen receptors ERα and ERβ), progesterone receptor (PR) and androgen receptor (AR), and the putative relevant ERRγ and GPER receptor were determined by RT-qPCR. Results: In diffuse GC, the expression of ERα, ERβ, PR and AR differed from their expression in the intestinal subtype. The expression of ERα and ERβ was strongly increased in the diffuse subtype compared to the intestinal subtype (×1.90, p = 0.001 and ×2.68, p = 0.002, respectively). Overexpression of ERα and ERβ was observed in diffuse GC (15 and 42%, respectively). The expression levels of PR and AR were strongly decreased in the intestinal subtype as compared to diffuse GC (×0.48, p = 0.005 and ×0.25, p = 0.003, respectively; 37.5% and 56% underexpression). ERα, ERβ, PR and AR showed notable differences for clinicopathological correlation in the diffuse and intestinal GC. A significant decrease of ERα, ERβ, PR and AR in intestinal GC correlated with the absence of lymphatic invasion and lower TNM (I-II). In diffuse GC, among the hormone receptors, increases of ERs and PR mainly correlated with expression of growth factors and receptors (IGF1, FGF7 and FGFR1), and with genes involved in epithelial-mesenchymal transition (VIM and ZEB2) or cell migration (MMP2). Our results also report the strong decreased expression of ERRγ and GPER (two receptors that bind estrogen or xenoestrogens) in diffuse and intestinal subtypes. Conclusions: Our study identified new target genes, namely hormone receptors and membrane receptors (ERRγ and GPER), whose expression is associated with an aggressive phenotype of diffuse GC, and revealed the importance of epigenetic factors (EZH2, HOTAIR, H19 and DNMT1) in gastric cancers.

Increasing epidemiological and animal experimental data provide substantial support for the role of aryl hydrocarbon receptor (AhR) in mammary tumorigenesis. The effects of AhR have been clearly demonstrated in rodent models of breast carcinogenesis and in several established human breast cancer cell lines following exposure to AhR ligands or AhR overexpression. However, relatively little is known about the role of AhR in human breast cancers. AhR has always been considered to be a regulator of toxic and carcinogenic responses to environmental contaminants such as TCDD (dioxin) and benzo[a]pyrene (BaP). The aim of this study was to identify the type of breast tumors (ERα-positive or ERα-negative) that express AHR and how AhR affects human tumorigenesis. The levels of AHR, AHR nuclear translocator (ARNT) and AHR repressor (AHRR) mRNA expression were analyzed in a cohort of 439 breast tumors, demonstrating a weak association between high AHR expression and age greater than fifty years and ERα-negative status, and HR-/ERBB2 breast cancer subtypes. AHRR mRNA expression was associated with metastasis-free survival, while AHR mRNA expression was not. Immunohistochemistry revealed the presence of AhR protein in both tumor cells (nucleus and/or cytoplasm) and the tumor microenvironment (including endothelial cells and lymphocytes). High AHR expression was correlated with high expression of several genes involved in signaling pathways related to inflammation (IL1B, IL6, TNF, IL8 and CXCR4), metabolism (IDO1 and TDO2 from the kynurenine pathway), invasion (MMP1, MMP2 and PLAU), and IGF signaling (IGF2R, IGF1R and TGFB1). Two well-known ligands for AHR (TCDD and BaP) induced mRNA expression of IL1B and IL6 in an ERα-negative breast tumor cell line. The breast cancer ER status likely influences AhR activity involved in these signaling pathways. The mechanisms involved in AhR activation and target gene expression in breast cancers are also discussed.

Gastric cancer (GC) is a highly heterogeneous disease and one of the major causes of cancer-related mortality worldwide. Diffuse-type gastric adenocarcinoma (or poorly cohesive- with independent cells) is characterized by aggressive behavior (rapid invasion, chemoresistance and peritoneal metastasis), as compared with intestinal-subtype adenocarcinoma. Diffuse subtype GC additionally has a substantially increasing incidence rate in Europe and the USA, and was often associated with younger age. Our objective was to analyze the expression and clinical significance of genes involved in several signaling pathways in diffuse-type GC. Tumors samples and non-malignant gastric tissues were obtained from patients with GC (diffuse-type and intestinal-subtype adenocarcinoma). The expression of 33 genes coding for proteins involved in four categories, growth factors and receptors, epithelial-mesenchymal transition, cell proliferation and migration, and angiogenesis was determined by reverse transcription-quantitative polymerase chain reaction. The expression of 22 genes was significantly upregulated in diffuse-type GC and two were downregulated (including CDH1) compared with normal tissues. Among these genes, acompared with intestinal-subtype adenocarcinoma, diffuse-type GC revealed elevated levels of IGF1 and IGF1R, FGF7 and FGFR1, ZEB2, CXCR4, CXCL12 and RHOA, and decreased levels of CDH1, MMP9 and MKI67. The expression of selected genes was compared with other genes and according to clinical parameters. Furthermore, TGF-β expression was significantly increased in linitis, a sub-population of diffusely infiltrating type associated with extensive fibrosis and tumor invasion. Our study identified new target genes (IGF1, FGF7, CXCR4, TG-β and ZEB2) whose expression is associated with aggressive phenotype of diffuse-type GC.

The vast majority of gastric cancer (GC) cases are adenocarcinomas including intestinal and diffuse GC. The incidence of diffuse GC, often associated with poor overall survival, has constantly increased in Western countries. Epidemiological studies have reported increased mortality from GC after occupational exposure to pro-carcinogens that are metabolically activated by cytochrome P450 enzymes through aryl hydrocarbon receptor (AhR). However, little is known about the role of AhR and environmental AhR ligands in diffuse GC as compared to intestinal GC in Western patients. In a cohort of 29, we demonstrated a significant increase in AhR protein and mRNA expression levels in GCs independently of their subtypes and clinical parameters. AhR and RHOA mRNA expression were correlated in diffuse GC. Further, our study aimed to characterize in GC how AhR and the AhR-related genes cytochrome P450 1A1 (CYP1A1) and P450 1B1 (CYP1B1) affect the mRNA expression of a panel of genes involved in cancer development and progression. In diffuse GC, CYP1A1 expression correlated with genes involved in IGF signaling, epithelial–mesenchymal transition (Vimentin), and migration (MMP2). Using the poorly differentiated KATO III epithelial cell line, two well-known AhR pollutant ligands, namely 2-3-7-8 tetrachlorodibenzo-p-dioxin (TCDD) and benzo[a]pyrene (BaP), strongly increased the expression of CYP1A1 and Interleukin1β (IL1B), and to a lesser extend UGT1, NQO1, and AhR Repressor (AhRR). Moreover, the increased expression of CYP1B1 was seen in diffuse GC, and IHC staining indicated that CYP1B1 is mainly expressed in stromal cells. TCDD treatment increased CYP1B1 expression in KATO III cells, although at lower levels as compared to CYP1A1. In intestinal GC, CYP1B1 expression is inversely correlated with several cancer-related genes such as IDO1, a gene involved in the early steps of tryptophan metabolism that contributes to the endogenous AhR ligand kynurenine expression. Altogether, our data provide evidence for a major role of AhR in GC, as an environmental xenobiotic receptor, through different mechanisms and pathways in diffuse and intestinal GC. Our results support the continued efforts to clarify the identity of exogenous AhR ligands in diffuse GC in order to define new therapeutic strategies.

Gastric cancer (GC) is one of the major causes of cancer-related mortality worldwide. The vast majority of GC cases are adenocarcinomas including intestinal and diffuse GC. The incidence of diffuse GCs, often associated with poor overall survival, has constantly increased in USA and Europe The molecular basis of diffuse GC aggressivity remains unclear. Using mRNA from diffuse and intestinal GC tumor samples of a Western cohort, this study reports the expression level of the immunomodulatory aryl-hydrocarbon receptor (AhR), and genes involved in immune suppression (PD1, PD-L1, PD-L2) and the early steps of tryptophan metabolism (IDO1, IDO2, TDO2). Strongly increased expression of IDO1 (p < 0.001) and PD1 (p < 0.003) was observed in the intestinal sub-type. The highest expression of IDO1 and PDL1 correlated with early clinical stage and absence of lymphatic invasion (×25 p = 0.004, ×3 p = 0.04, respectively). Our results suggest that kynurenine, produced by tryptophan catabolism, and AhR activation play a central role in creating an immunosuppressive environment. Correspondingly, as compared to intestinal GCs, expression levels of IDO1-TDO2 and PD-L1 were less prominent in diffuse GCs which also had less infiltration of immune cells, suggesting an inactive immune response in the advanced diffuse GC. Confirmation of these patterns of gene expression will require a larger cohort of early and advanced stages of diffuse GC samples.

Endothelial dysfunction has been implicated in the pathogenesis of diverse pathologies ranging from vascular and immune diseases to cancer. TNF-α is one of the mediators of endothelial dysfunction through the activation of transcription factors, including NF-κB. While HUVEC (macrovascular cells) have been largely used in the past, here, we documented an NF-κB gene signature in TNFα-stimulated microvascular endothelial cells HMEC often used in tumor angiogenesis studies. We measured mRNA expression of 55 NF-κB related genes using quantitative RT-PCR in HUVEC and HMEC. Our study identified twenty genes markedly up-regulated in response to TNFα, including adhesion molecules, cytokines, chemokines, and apoptosis regulators, some of them being identified as TNF-α-inducible genes for the first time in endothelial cells (two apoptosis regulators, TNFAIP3 and TNFRSF10B/Trail R2 (DR5), the chemokines GM-CSF/CSF2 and MCF/CSF1, and CD40 and TNF-α itself, as well as NF-κB components (RELB, NFKB1 or 50/p105 and NFKB2 or p52/p100). For eight genes, the fold induction was much higher in HMEC, as compared to HUVEC. Most importantly, our study described for the first time a connection between NF-κB activation and the induction of most, if not all, of these genes in HMEC as evaluated by pharmacological inhibition and RelA expression knock-down by RNA interference. Moreover, since TNF-α is highly expressed in tumors, we further applied the NF-κB gene signature documented in TNFα-stimulated endothelial cells to human breast tumors. We found a significant positive correlation between TNF and the majority (85 %) of the identified endothelial TNF-induced genes in a well-defined series of 96 (48 ERα positive and 48 ERα negative) breast tumors. Taken together these data suggest the potential use of this NF-κB gene signature in analyzing the role of TNF-α in the endothelial dysfunction, as well as in breast tumors independently of the presence of ERα.

A key mechanism underlying physiological angiogenesis of the human endometrium is its ability to regenerate the vascular capillary network and to perform vascular remodeling (i.e., development of spiral arteries). Vascular endothelial growth factor (VEGF) is associated with angiogenesis and capillary permeability in this tissue. VEGF is expressed as several spliced variants, its main human isoforms contain 121 and 165 aa; 17β-estradiol (E2) increases endometrial VEGF, possibly in all isoforms. Here we show that progesterone (P) selectively increases the expression of the $VEGF_{189}\\>(V_{189})$ isoform in the human uterus. V189 is identified in the conditioned medium of stromal cells treated with E2 + P; its presence in this in vitro model of decidual stromal cells is detected after 6-8 days, using ELISA, and after 8-10 days, using Western blot analysis with different antibodies, including one specific for V189. The secretion pattern of V189 parallels that of the decidual protein IGFBP-1. V189 is secreted as a native isoform, as compared with the migration of recombinant V189 by SDS/PAGE. In situ hybridization and immunocytochemistry, performed on the same biopsies, suggest that decidual cells express V189 during the midlate secretory phase of the menstrual cycle and early gestation. Finally, using an in vivo permeability assay, we show that native V189 increases capillary permeability. These observations demonstrate that P regulates V189 expression in decidual cells, which could have important implications for understanding uterine vascular remodeling and implantation, and may be relevant in a range of disease states such as edema and irregular bleeding.

Vascular endothelial growth factor (VEGF) is a potent and specific endothelial cell mitogen involved in normal and pathological angiogenesis. Our group recently reported that, among the several VEGF isoforms, VEGF189 (V189) is selectively induced in decidual endometrial cells during the mid-late phase of the menstrual cycle, together with polymorphonuclear neutrophil (PMN) influx. We thus compared the effects of various VEGF isoforms on PMN migration in vitro, and the mechanisms involved. In transmigration and under-agarose assays, V189 was both chemotactic and chemokinetic for PMN, while VEGF165 (V165) was only chemokinetic. The chemokinetic effect of V189 for PMN was blocked by neutralizing anti-VEGF antibodies, but not by neutralizing anti-KDR antibodies, suggesting that the Flt-1 VEGF receptor that is expressed in PMN mediates these effects. Flow cytometric analysis of several adhesion molecules at the PMN surface showed that all VEGF isoforms slightly upregulated β1- and β2-integrins and PECAM, and downregulated L-selectin; all these molecules are activation markers. The involvement of β1-integrins was further supported by the ability of blocking antibodies to reduce VEGF-induced PMN migration. As human PMN can secrete several cytokines and growth factors, the selective secretion of VEGF isoforms was also further examined. RT-PCR analysis showed that V165 mRNA was more strongly expressed than V189 mRNA. Conversely, the major protein isoform secreted after optimal PMN degranulation was V189, which was located in both azurophilic and specific granules. PMN-derived VEGF can thus modulate PMN migration. This autocrine amplification mechanism would allow sustained VEGF release to occur at inflammatory sites, and may contribute to both normal and pathological angiogenesis.

Vascular endothelial growth factor (VEGF) is an endothelium-specific growth factor with potent angiogenic activity and a stimulator of microvascular permeability. Because endometrial cyclic development is associated with vascular growth, we examined the expression of VEGF protein throughout the menstrual cycle and studied the regulation of VEGF mRNA by ovarian steroids in isolated human endometrial stromal cells. VEGF was localized immunohistochemically in glandular epithelial cells and in the surrounding stroma, as well as in capillaries and spiral arterioles, a localization which has not been described before. The strongest immunoreactivity for VEGF on endothelial cells was detected in the late proliferative and secretory phases. The localization of VEGF bound to the endothelium correlates with the presence of flt-1 and flk/KDR receptors on vascular structures, including capillary strands which have not yet formed a lumen, present during the mid-secretory period, which corresponds to a high estroprogestin influence and to implantation. Heparinase treatment of the sections decreases the staining intensity of VEGF bound to endothelial cells, suggesting that VEGF also binds to heparin-like molecules on the cell surface. These new results demonstrate a major role of VEGF on capillary formation and on hyperpermeability and edema during the menstrual cycle. Consistent with these in vivo observations, the treatment of isolated endometrial stromal cells with estradiol (E2) or E2 plus progesterone, significantly increased VEGF mRNA over the control value in a dose-dependent manner; the VEGF mRNA response to E2 was rapid (3h) and persisted with continuous estradiol treatment up to 12 days. Three species, VEGF_121, VEGF165 and VEGF189, were observed upon hormonal stimulation. The estradiol up-regulation of VEGF response did not require de novo protein synthesis as it was not blocked by cycloheximide. Also, the ability of the pure anti-estrogen ICI 182,780 to significantly block induction of VEGF mRNA by E2 suggests estrogen receptor-mediated transcriptional regulation. These results demonstrate that VEGF is an estrogen-responsive angiogenic factor that acts on vascular endothelium in a paracrine fashion, as previously suggested. This growth factor controls angiogenesis and hyperpermeability required for adequate receptivity to implantation of the cycling human endometrium. These findings also raise the possibility that estrogen effects on uterine edema, proliferation and tumoral transformation may involve local increases in tissue VEGF production.

Endothelial dysfunction has been implicated in the pathogenesis of diverse pathologies ranging from vascular and immune diseases to cancer. TNF-[alpha] is one of the mediators of endothelial dysfunction through the activation of transcription factors, including NF-[kappa]B. While HUVEC (macrovascular cells) have been largely used in the past, here, we documented an NF-[kappa]B gene signature in TNF[alpha]-stimulated microvascular endothelial cells HMEC often used in tumor angiogenesis studies. We measured mRNA expression of 55 NF-[kappa]B related genes using quantitative RT-PCR in HUVEC and HMEC. Our study identified twenty genes markedly up-regulated in response to TNF[alpha], including adhesion molecules, cytokines, chemokines, and apoptosis regulators, some of them being identified as TNF-[alpha]-inducible genes for the first time in endothelial cells (two apoptosis regulators, TNFAIP3 and TNFRSF10B/Trail R2 (DR5), the chemokines GM-CSF/CSF2 and MCF/CSF1, and CD40 and TNF-[alpha] itself, as well as NF-[kappa]B components (RELB, NFKB1or 50/p105 and NFKB2 or p52/p100). For eight genes, the fold induction was much higher in HMEC, as compared to HUVEC. Most importantly, our study described for the first time a connection between NF-[kappa]B activation and the induction of most, if not all, of these genes in HMEC as evaluated by pharmacological inhibition and RelA expression knock-down by RNA interference. Taken together these data suggest the potential use of this NF-[kappa]B gene signature in analyzing the role of TNF-[alpha] in the endothelial dysfunction, as well as in breast tumors independently of the presence of ER[alpha].