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While progress has been made in treating primary epithelial tumors, metastatic tumors remain largely incurable and still account for 85-90 % of all cancer-related deaths. Interleukin-4 (IL4), a Th2 cytokine, and the IL4/IL4 receptor (IL4R) interaction have well defined roles in the immune system. Yet, IL4 receptors are over-expressed by many epithelial cancers and could be a promising target for metastatic tumor therapy. The IL4/IL4R signaling axis is a strong promoter of pro-metastatic phenotypes in epithelial cancer cells including enhanced migration, invasion, survival, and proliferation. The promotion of breast cancer growth specifically is also supported in part by IL4-induced glutamine metabolism, and we have shown that IL4 is also capable of inducing glucose metabolism in breast cancer cells. Importantly, there are several types of FDA approved medications for use in asthma patients that inhibit the IL4/IL4R signaling axis. However, these approved medications inhibit both the type I IL4 receptor found on immune cells, and the type II IL4 receptor that is predominantly expressed by some non-hematopoietic cells including epithelial cancer cells. This article reviews existing therapies targeting IL4, IL4R, or IL4/IL4R signaling, and recent findings guiding the creation of novel therapies that specifically inhibit the type II IL4R, while taking into consideration effects on immune cells within the tumor microenvironment. Some of these therapies are currently in clinical trials for cancer patients, and may be exploitable for the treatment of metastatic disease.
BACKGROUND - Infection with Helicobacter pylori, a high-risk factor for gastric cancer, is frequently associated with chronic inflammation through activation of nuclear factor κB (NF-κB). Trefoil factor 1 (TFF1) is a constitutively expressed protein in the stomach that has tumor-suppressor functions and plays a critical role in maintaining mucosal integrity. This study investigated the role of TFF1 in regulating the proinflammatory response to H. pylori infections.
METHODS - For in vitro studies, immunofluorescence, luciferase reporter assays, Western blots, and quantitative real-time polymerase chain reaction were performed to investigate the activation of NF-κB and its target genes in response to infections with H. pylori strains J166 and 7.13. In addition, Tff1-knockout (KO) and Tff1-wild-type mice were used for infections with the H. pylori strain called premouse Sydney strain 1.
RESULTS - The reconstitution of TFF1 expression in gastric cancer cells significantly suppressed H. pylori-mediated increases in NF-κB-p65 nuclear staining, transcriptional activity, and expression of proinflammatory cytokine genes (tumor necrosis factor α, interleukin 1β, chemokine [C-X-C motif] ligand 5, and interleukin 4 receptor) that were associated with reductions in the expression and phosphorylation of NF-κB-p65 and IκB kinase α/β proteins. The in vivo studies using the Tff1-KO mouse model of gastric neoplasia confirmed the in vitro findings. Furthermore, they demonstrated increases in chronic inflammation scores and in the frequency of invasive gastric adenocarcinoma in the Tff1-KO mice infected with H. pylori versus the uninfected Tff1-KO mice.
CONCLUSIONS - These findings underscore an important protective role of TFF1 in abrogating H. pylori-mediated inflammation, a crucial hallmark of gastric tumorigenesis. Therefore, loss of TFF1 expression could be an important step in H. pylori-mediated gastric carcinogenesis.
© 2015 American Cancer Society.
The type II interleukin-4 receptor (IL4R) is expressed in human breast cancer, and in murine models thereof. It is activated by interleukin-4 (IL4), a cytokine produced predominantly by immune cells. Previously, we showed that expression of IL4Rα, a signaling component of IL4R, mediates enhanced metastatic growth through promotion of tumor cell survival and proliferation. In lymphocytes, these processes are supported by increased glucose and glutamine metabolism, and B lymphocyte survival is dependent upon IL4/IL4R-induced glucose metabolism. However, it is unknown whether IL4R-mediated metabolic reprogramming could support tumor growth. Here, we show that IL4Rα expression increases proliferation thus enhancing primary mammary tumor growth. In vitro, IL4-enhanced glucose consumption and lactate production in 4T1 cells was mediated by IL4Rα. Expression of the glucose transporter GLUT1 increased in response to IL4 in vitro, and enhanced GLUT1 expression was associated with the presence of IL4Rα in 4T1 mammary tumors in vivo. Although IL4 treatment did not induce changes in glucose metabolism in MDA-MB-231 human breast cancer cells, it increased expression of the main glutamine transporter, ASCT2, and enhanced glutamine consumption in both MDA-MB-231 and 4T1 cells. Pharmacologic inhibition of glutamine metabolism with compound 968 blocked IL4/IL4Rα-increased cell number in both cell lines. Our results demonstrate that IL4R mediates enhanced glucose and glutamine metabolism in 4T1 cancer cells, and that IL4-induced growth is supported by IL4/IL4R-enhanced glutamine metabolism in both human and murine mammary cancer cells. This highlights IL4Rα as a possible target for effective breast cancer therapy.
Copyright © 2015 Elsevier B.V. All rights reserved.
The Th2 cytokines interleukin (IL)-4 and -13 are acknowledged regulators of lymphocyte proliferation and activation. They have also been well studied in the regulation of various myeloid-derived populations in tumor biology. It has become clear, however, that both cytokines can have direct effects on epithelial tumor cells expressing appropriate receptors. Changes in tumor proliferation, survival, and metastatic capability have all been ascribed to IL-4 and/or IL-13 action. Here, we evaluate the evidence to support direct tumor-promoting roles of these cytokines. We also identify the questions that should be addressed before proceeding with therapeutic approaches based on neutralization of IL-4 or IL-13 pathways.
Inflammatory mediators are of considerable interest as potential therapeutic targets in various cancers. Here we investigate whether interleukin (IL)-4 receptor alpha (IL4Ralpha), a component of the receptor complex for the T helper 2 cytokines IL4 and IL13, plays a role in colonic tumorigenesis. IL4Ralpha protein expression was seen in tumor cells of 28/48 human colon adenocarcinomas on a tissue microarray. In human and murine colon tumor cell lines analyzed in vitro, all of which expressed IL4Ralpha, treatment with exogenous ligand resulted in dose-dependent increases in proliferation. IL4 decreased apoptosis only in HCT116 cells. An orthotopic allograft model was used to determine in vivo effects of tumor cell-specific IL4Ra ablation. MC38 murine tumor cells with the IL4Ra gene knocked down showed reduced proliferation but no difference in apoptosis compared with controls after implantation in ceca of syngeneic mice. Mice null for IL4Ra and wild-type controls were treated with azoxymethane and dextran sulfate sodium to induce tumor formation. Mice with global deletion of IL4Ra had significantly fewer and smaller tumors. Reduced tumorigenicity correlated with decreased proliferation and increased apoptosis. Systemic blockade of IL4Ralpha-IL4 interactions with a chimeric soluble receptor protein gave similar results in the cecal implant model. Thus, IL4Ralpha, a component of the IL4R and IL13R, contributes to tumor formation in a mouse model of colitis-associated cancer. Proliferation appears to be directly mediated via IL4Ralpha on the epithelial tumor cells. Survival may be an indirect response mediated via other host cells. Our results support therapeutic targeting of IL4Ralpha in colon cancer.
Several commonly occurring polymorphisms in the IL-4R(alpha) have been associated with atopy in humans; the Q576R and the S503P polymorphisms reside in the cytoplasmic domain, whereas the I50 to V50 polymorphism resides in the extracellular domain of the IL-4R(alpha). The effects of these polymorphisms on signaling remain controversial. To determine the effect of the polymorphisms on IL-4 signaling in human cells, we stably transfected the human monocytic cell line U937 with murine IL-4R(alpha) cDNA bearing the I or V at position 50 and the P503/R576 double mutant. Each form of the murine IL-4R(alpha) mediated tyrosine phosphorylation of STAT6 in response to murine IL-4 treatment similar to the induction of tyrosine phosphorylation by human IL-4 signaling through the endogenous human IL-4R(alpha). After IL-4 removal, tyrosine-phosphorylated STAT6 rapidly decayed in cells expressing I50 or P503R576 murine IL-4Ralpha. In contrast, STAT6 remained significantly phosphorylated for several hours after murine IL-4 withdrawal in cells expressing the V50 polymorphism. This persistence in tyrosine-phosphorylated STAT6 was associated with persistence in CIS mRNA expression. Blocking IL-4 signaling during the decay phase using the JAK inhibitor AG490 or the anti-IL-4R(alpha) Ab M1 abrogated the persistence of phosphorylated STAT6 observed in the V50-IL-4R(alpha)-expressing cells. These results indicate that the V50 polymorphism promotes sustained STAT6 phosphorylation and that this process is mediated by continued engagement of IL-4R(alpha), suggesting enhanced responses of V50 IL-4R when IL-4 is limiting.
BACKGROUND - Eotaxin is implicated in asthmatic eosinophilia. Oncostatin M (OSM) causes eotaxin release from fibroblasts.
OBJECTIVE - We sought to examine the effects and mechanism of action of OSM and other IL-6 family cytokines on eotaxin release from human airway smooth muscle cells.
METHODS - Eotaxin 1 release was measured by means of ELISA. Western blotting was used to examine mitogen-activated protein kinase and signal transducer and activator of transcription 3 (STAT-3) phosphorylation. Eotaxin promoter activity was analyzed in cells transfected with wild-type STAT-3, a mutant form of STAT-3 that cannot be phosphorylated, and a constitutively active form of STAT-3. The mRNA and protein expression of IL-4R alpha, the signaling receptor for IL-4 and IL-13, was evaluated by means of real-time PCR and flow cytometry, respectively.
RESULTS - OSM increased eotaxin 1 release and augmented IL-4- or IL-13-induced eotaxin release, whereas other IL-6 family cytokines did not. OSM caused a greater increase in STAT-3 phosphorylation and STAT-3-mediated gene transcription than other IL-6 family cytokines. OSM increased eotaxin promoter activity and augmented IL-13- and IL-4-induced increases in promoter activity. The constitutively active form of STAT-3 increased eotaxin promoter activity, whereas the mutant form of STAT-3 that cannot be phosphorylated significantly reduced eotaxin promoter activity induced by OSM or IL-4 plus OSM. OSM increased IL-4R alpha mRNA and protein levels.
CONCLUSIONS - OSM induces eotaxin 1 expression in human airway smooth muscle cells by a mechanism involving STAT-3. OSM synergizes with IL-13 and IL-4 to increase eotaxin 1 expression, possibly as a result of effects on IL-4R alpha expression.
Signaling through the IL-4R alpha-chain (IL-4Ralpha) is crucial for the development of Th2 cells, central effectors in atopic disease. Alleles of the IL-4Ralpha have been identified that have been variably associated with increased incidence of allergic disease, but there is little direct evidence that any variant is sufficient to alter a target that determines allergic pathophysiology or susceptibility. Variants of IL-4Ralpha encoding isoleucine instead of valine at position 50 (I50 vs V50, respectively) can signal increased Stat6-dependent transcriptional activity, whether in an I50, Q551 or I50, R551 haplotype. Strikingly, signaling through these receptors did not increase the efficiency of Th2 development or the IL-4 mediated repression of Th1 development or a target gene, IL-18Ralpha. Further, IL-4-induced proliferation was similar for Th2 cells independent of the variant expressed. Together these findings indicate that IL-4Ralpha variants that exhibit gain-of-function with respect to Stat6 do not act directly through alterations in Th2/Th1 induction after Ag exposure. The data further suggest that for such variants, any mechanistic involvement is based on a role in cellular targets of Th2 cytokines.
Signaling by the IL-4 receptor alpha-chain (IL-4Ralpha) is a key determinant of the development of the Th2 lineage of effector T cells. Studies performed in tissue culture cell lines have indicated that tyrosines of the IL-4Ralpha cytoplasmic tail are necessary for the induction of Stat6, a transcription factor required for Th2 differentiation. Surprisingly, we have found that in activated T cells, IL-4Ralpha chains lacking all cytoplasmic tyrosines promote induction of this IL-4-specific transcription factor and efficient commitment to the Th2 lineage. Mutagenesis of a tyrosine-free cytoplasmic tail identifies a requirement for the serine-rich ID-1 region in this new program of IL-4R signal transduction observed in activated T cells. Additional findings suggest that an extracellular signal-regulated kinase pathway can be necessary and sufficient for the ability of such tyrosine-free IL-4Ralpha chains to mediate Stat6 induction. These results provide novel evidence that the molecular mechanisms by which a cytokine specifically induces a Stat transcription factor can depend on the activation state of T lymphoid cells. Furthermore, the data suggest that one pathway by which such new programming may be achieved is mediated by extracellular signal-regulated mitogen-activated protein kinases.
The chemokine thymus- and activation-regulated chemokine (TARC) induces selective migration of Th2, but not Th1, lymphocytes and is upregulated in the airways of asthmatic patients. The purpose of this study was to determine whether human airway smooth muscle (HASM) cells produce TARC. Neither IL-4, IL-13, IL-1beta, IFN-gamma, nor TNF-alpha alone stimulated TARC release into the supernatant of cultured HASM cells. However, both IL-4 and IL-13 increased TARC protein and mRNA expression when administered in combination with TNF-alpha but not IL-1beta or IFN-gamma. Macrophage-derived chemokine was not expressed under any of these conditions. TARC release induced by TNF-alpha + IL-13 or TNF-alpha + IL-4 was inhibited by the beta-agonist isoproterenol and by other agents that activate protein kinase A, but not by dexamethasone. To determine whether polymorphisms of the IL-4Ralpha have an impact on the ability of IL-13 or IL-4 to induce TARC release, HASM cells from multiple donors were genotyped for the Ile50Val, Ser478Pro, and Gln551Arg polymorphisms of the IL-4Ralpha. Our data indicate that cells expressing the Val50/Pro478/Arg551 haplotype had significantly greater IL-13- or IL-4-induced TARC release than cells with other IL-4Ralpha genotypes. These data indicate that Th2 cytokines enhance TARC expression in HASM cells in an IL-4Ralpha genotype-dependent fashion and suggest that airway smooth muscle cells participate in a positive feedback loop that promotes the recruitment of Th2 cells into asthmatic airways.