TLR-4 signaling promotes tumor growth and paclitaxel chemoresistance in ovarian cancer

Modulation and recruitment of inducible regulatory T cells by first trimester trophoblast cells

PROBLEM  The specialized regulatory T-cells (Treg) population, essential for maternal tolerance of the fetus, performs its suppressive actions in the critical peri-implantation phase of pregnancy. In the present work, we investigated whether trophoblast cells are able to induce Treg recruitment, differentiation, and whether these mechanisms are modified by a bacterial or viral infection. METHOD OF STUDY  Human T-regulatory cells were differentiated from naïve CD45RA(+) CCR7(+) cells obtained from peripheral blood mononuclear cells cultured with IL-2 and TGFβ over 5 days. Induction of iTregs (CD4(+)  Foxp3(+) cells) was evaluated using low serum conditioned media (LSCM), obtained from two first trimester trophoblast cell lines, Swan-71 and HTR8. Coculture experiments were carried out using transwell assays where trophoblast cells were in the absence or presence of PGN, LPS, or Poly [I:C]. Cytokine production was measured by multiplex analysis. RESULTS  Trophoblast cells constitutively secrete high levels of TGFβ and induced a significant increase of Foxp3 expression accompanied by a specific T-reg cytokine profile. Moreover, trophoblast cells were able to recruit iTregs in a specific manner. CONCLUSION  We demonstrate that trophoblast cells have an active role on the recruitment and differentiation of iTregs, therefore, contributing to the process of immune regulation at the placental-maternal interface.

Tissue expression of Toll-like receptors 2 and 4 in sporadic human colorectal cancer

Background

Toll-like receptors (TLRs) play an important role in innate immunity by sensing a variety of pathogens and inducing acquired immunity. To test our hypothesis that dysregulation of innate immune responses acts to trigger carcinogenesis, we studied the expression of TLR2 and 4 in sporadic human colorectal cancer tissue.

Methods

In specimens of cancerous and noncancerous colorectal tissue obtained at surgery, mRNA expression levels of TLR2 and 4 were quantified by TaqMan real-time polymerase chain reaction and compared between the two types of tissue. To confirm TLR2 and TLR4 protein expression levels, immunohistochemical analysis was performed using the same samples.

Results

TLR2 mRNA expression was significantly higher in cancerous tissue than in noncancerous tissue, while TLR4 mRNA expression did not differ significantly. Immunohistochemical analysis revealed stronger staining for TLR2 in cancerous mucosal epithelial cells than in noncancerous tissue. Staining for TLR4 in the lamina propria of the mucosa was equally weakly positive in noncancerous tissue and cancerous tissue. This TLR-specific difference in expression suggested that such expression does not only reflect a local inflammatory response to cancer infiltration, i.e., if this was the case, both TLR2 and 4 expression would probably be up-regulated. Our results suggest that TLR2 expression might be involved in sporadic colorectal carcinogenesis, whereas TLR4 is not.

The dual role of TLR3 in metastatic cell line

Toll-like receptors (TLRs) are members of transmembrane proteins that recognize conserved molecular motifs of viral and bacterial origin and initiate innate immune response. As the role of TLRs in tumors cells is still not clear, our aim was to investigate the role of TLR3 in primary tumor and metastatic cells (SW480, SW620, FaDu and Detroit 562). We have reported here on the dual role of TLR3 in pharynx metastatic cell line (Detroit 562); on one hand TLR3 activation drove cells to apoptosis while on the other its stimulation contributed to tumor progression by altering the expression of tumor promoting genes (PLAUR, RORB) and enhancing the cell migration potential. In addition, we have shown TLR3 signaling pathway is functional in another metastatic cancer cell line (SW620) suggesting TLR3 might be important in the process of tumor metastasis. Since TLR3 agonists have been used in tumor therapy with the aim to activate immune system, scientific contribution of this work is drawing attention to the importance of further work on this topic, especially pro-tumor effect of TLR3, in order to avoid possible side-effects.

Inhibition of Aurora-A kinase induces cell cycle arrest in epithelial ovarian cancer stem cells by affecting NFĸB pathway

Recurrent ovarian cancer is resistant to conventional chemotherapy. A sub-population of ovarian cancer cells, the epithelial ovarian cancer stem cells (EOC stem cells) have stemness properties, constitutive NFκB activity, and represent the chemoresistant population. Currently, there is no effective treatment that targets these cells. Aurora-A kinase (Aurora-A) is associated with tumor initiation and progression and is overexpressed in numerous malignancies. The aim of this study is to determine the effect of Aurora-A inhibition in EOC stem cells. EOC stem cells were treated with the Aurora-A inhibitor, MK-5108. Cell growth was monitored by Incucyte real-time imaging system, cell viability was measured using the Celltiter 96 assay and cytokine levels were quantified using xMAP technology. The intracellular changes associated with MK-5108 treatment are: (1) polyploidy and cell cycle arrest; (2) inhibition of NFκB activity; (3) decreased cytokine production; and (4) nuclear accumulation of IκBα. Thus, inhibition of Aurora-A decreases cell proliferation in the EOC stem cells by inducing cell cycle arrest and affecting the NFκB pathway. As EOC stem cells represent a source of recurrence and chemoresistance, these results suggest that Aurora-A inhibition may effectively target the cancer stem cell population in ovarian cancer.

Endogenous toll-like receptor ligands and their biological significance

Toll-like receptors (TLRs), a family of pattern recognition receptors, recognize and respond to conserved components of microbes and play a crucial role in both innate and adaptive immunity. In addition to binding exogenous ligands derived from pathogens, TLRs interact with endogenous molecules released from damaged tissues or dead cells and regulate many sterile inflammation processes. Putative endogenous TLR ligands include proteins and peptides, polysaccharides and proteoglycan, nucleic acids and phospholipids, which are cellular components, particularly extracellular matrix degradation products. Accumulating evidence demonstrates that endogenous ligand-mediated TLR signalling is involved in pathological conditions such as tissue injury, repair and regeneration; autoimmune diseases and tumorigenesis. The ability of TLRs to recognize endogenous stimulators appears to be essential to their function in regulating non-infectious inflammation. In this review, we summarize current knowledge of endogenous TLR ligands and discuss the biological significance of TLR signalling triggered by endogenous ligands in several sterile inflammation conditions.

TLR4 activates NF-κB in human ovarian granulosa tumor cells

Previous studies have demonstrated expression of Toll-like receptors (TLRs) in the surface epithelium of normal ovaries (OSE) and in epithelial ovarian tumors. Most notably, OSE-derived cancers express TLR4, which activates the nuclear factor-kappa B (NF-κB) signaling cascade as a mediator of inflammatory response. Currently, there is considerable interest in elucidating the role of TLR-mediated signaling in cancers. Nevertheless, the expression of TLRs in granulosa cell tumors (GCTs) of the ovary, and the extent to which GCT expression of TLRs may influence cell-signaling pathways and/or modulate the efficacy of chemotherapeutics, has yet to be determined. In the present study, human GCT lines (COV434 and KGN) were utilized to evaluate expression of functional TLR4. TLR4 is expressed in GCT cell lines and ligation of TLR4 with bacterial lipopolysaccharide (LPS) led to IκB degradation and activation of NF-κB. NF-κB activation was confirmed by nuclear localization of NF-κB p65 following treatment with LPS and the naturally occurring ligand, HSP60. Notably, immunoneutralization of TLR4 blocked nuclear localization, and inhibition of NF-κB signaling attenuated LPS-induced TNFα plus increased doubling time in both cell lines. Contradictory to reports using human OSE cell lines, inhibition of NF-κB signaling failed to sensitize GCT lines to TRAIL or cisplatin. In summary, findings herein are the first to demonstrate a functional TLR-signaling pathway specifically in GCTs, and indicate that in contrast to OSE-derived cancers, inhibition of NF-κB does not sensitize GCTs to TRAIL or cisplatin.

TLR based therapeutics

Toll-like receptors (TLRs) play a crucial role in innate immune responses to infection. Binding of agonists to TLRs promotes maturation of antigen presenting cells, such as dendritic cells, which in turn directs the induction of adaptive immune responses. For this reason TLR agonists are being exploited as vaccine adjuvants for infectious disease or cancer and as therapeutics against tumors. However TLR agonists also promote inflammatory cytokine production and have a pathogenic role in many diseases with an inflammatory basis, including autoimmune diseases. Consequently, antibodies to TLRs and inhibitors of TLR signalling pathways have considerable potential as therapeutics for inflammatory disorders. Some have shown to be efficacious in pre-clinical models, and have now entered clinical trials.

Ovarian cancer stem cells and inflammation

Epithelial ovarian cancer (EOC) is the fourth leading cause of cancer-related deaths in women in the United States and the leading cause of gynecologic cancer deaths. The major limiting factor in the treatment of ovarian cancer is recurrence and chemoresistance. Individuals who succumb to advanced-stage ovarian cancer inevitably become refractory to chemotherapy, resulting in disease progression and death. The source of recurrence and lack of response to chemotherapy is unknown. The focus of this review is to evaluate the question of recurrence and chemoresistance based on the concept of the cancer stem cells and inflammation.

Activation of Toll-like receptor 5 on breast cancer cells by flagellin suppresses cell proliferation and tumor growth

Increasing evidence showed that Toll-like receptors (TLR), key receptors in innate immunity, play a role in cancer progression and development but activation of different TLRs might exhibit the exact opposite outcome, antitumor or protumor effects. TLR function has been extensively studied in innate immune cells, so we investigated the role of TLR signaling in breast cancer epithelial cells. We found that TLR5 was highly expressed in breast carcinomas and that TLR5 signaling pathway is overly responsive in breast cancer cells. Interestingly, flagellin/TLR5 signaling in breast cancer cells inhibits cell proliferation and an anchorage-independent growth, a hallmark of tumorigenic transformation. In addition, the secretion of soluble factors induced by flagellin contributed to the growth-inhibitory activity in an autocrine fashion. The inhibitory activity was further confirmed in mouse xenografts of human breast cancer cells. These findings indicate that TLR5 activation by flagellin mediates innate immune response to elicit potent antitumor activity in breast cancer cells themselves, which may serve as a novel therapeutic target for human breast cancer therapy.

Expression of Toll-like receptor 4 and beta 1 integrin in breast cancer

Toll-like receptor (TLR) 4 signaling pathway has been shown to support tumor cell growth in vitro and in vivo. Its stimulation on breast cancer cell lines induces β1 integrin and promotes tumor invasiveness. However, its role in predicting clinical behavior of tumor is not yet clarified. Therefore, we investigated TLR4 and β1 integrin expression on 133 primary breast cancer samples by immunohistochemistry and correlated it with overall survival and disease-free survival of patients as well as with clinicopathological characteristics of the tumor. We found higher β1 integrin expression in invasive lobular cancer in comparison with other tumor types. No significant association of TLR4 and β1 integrin expression with overall survival or disease-free survival was seen. Therefore, we conclude that expression of these markers is of biological interest but appears to be of little additional use as predictive clinical marker.

Effects of CPG ODN on biological behavior of PANC-1 and expression of TLR9 in pancreatic cancer

AIM: To determine the expression of toll-like receptor 9 (TLR9) in pancreatic tumor and the effects of cytosine phosphate-guanosine oligodeoxynucleotides 2216 (CPG ODN2216) on biological behavior of pancreatic carcinoma cell line PANC-1 and explore their clinical significance.

METHODS: The immunohistochemistry and Western blot were used to determine the expression of TLR9 protein in pancreatic cancer tissues, and immunofluorescence staining was performed to detect the TLR9 protein expression in pancreatic carcinoma cell line PANC-1. To assess the effects of CPG ODN2216 on the invasive property of Panc-1 cells, in vitro cell adhesion, wound-healing scrape, and invasion and cell colony formation were evaluated.

RESULTS: TLR9 was highly expressed in pancreatic cancer tissues and PANC-1 cells. The percentage of positive cells expressing TLR9 protein in human pancreatic tissues, paracancerous tissues and normal tissues were 73.3%, 33.3% and 20.0%, respectively, and the protein expression level of TLR9 was gradually descending (P < 0.05). In vitro tests in wound-healing scrape, cell adhesion, colony formation and matrigel invasion showed that the adhesion and motility of PANC-1 cells in CPG ODN 2216 treatment group were significantly lower than in the control group (P < 0.05). The cell growth assay showed that the proliferative ability of PANC-1 cells in treatment group was significantly decreased and CPG ODN2216 had an inhibitive effect in the growth of Panc-1 cells in a dose and time-dependent manner (P < 0.05).

CONCLUSION: The gene of TLR9 is correlated with the invasive and metastatic potential of human pancreatic carcinoma, and CPG ODN2216 induces the inhibition of migration and invasion of Panc-1 cells.

Study of TLR3, TLR4, and TLR9 in prostate carcinomas and their association with biochemical recurrence

BACKGROUND

Toll-like receptors (TLRs) have garnered an extraordinary amount of interest in cancer research due to their role in tumor progression. By activating the production of several biological factors, TLRs induce type I interferons and other cytokines, which drive an inflammatory response and activate the adaptive immune system. The aim of this study was to investigate the expression and clinical relevance of TLR3, 4, and 9 in prostate cancer.

METHODS

The expression levels of TLR3, TLR4, and TLR9 were analyzed on tumors from 133 patients with prostate cancer. The analyses were performed by immunohistochemistry on tissue arrays and real time-PCR.

RESULTS

Cancerous cells showed high expression levels of TLRs compared with controls. Samples of carcinomas with recurrence exhibited a significant increase in the mRNA levels of TLR3, TLR4, and TLR9. In addition, the tumors that showed high TLR3 or TLR9 expression levels were significantly associated with higher probability of biochemical recurrence.

CONCLUSION

TLR expression is associated with prostate cancer with recurrence and the role of TLR receptors in the biology of malignancy merits study. Therapeutic strategies to boost or block TLRs may be of interest.

Pancreatic adenocarcinoma upregulated factor promotes metastasis by regulating TLR/CXCR4 activation

Pancreatic adenocarcinoma upregulated factor (PAUF) is overproduced in certain types of cancer. However, little is known of the tumorigenic function of PAUF. In this study, we report the X-ray crystal structure of PAUF and reveal that PAUF is a mammalian lectin normally found in plant lectins. We also identify PAUF as an endogenous ligand of Toll-like receptor 2 (TLR2) and TLR4 by screening extracellular domain receptor pools. We further confirmed the specificity of the PAUF-TLR2 interaction. PAUF induces extracellular signal-regulated kinase (ERK) phosphorylation and activates the IKK-β-mediated TPL2/MEK/ERK signaling pathway through TLR2. In agreement with the result of TLR2-mediated ERK activation by PAUF, PAUF induces increased expression of the protumorigenic cytokines RANTES and MIF in THP-1 cells. However, PAUF does not fully activate Iκ-B-α signaling pathways in THP-1 cells, and fails to translocate the p65 subunit of the nuclear factor-κB (NF-κB) complex into the nucleus, resulting in no NF-κB activation. Surprisingly, we found that PAUF also associated with the CXC chemokine receptor (CXCR4)-TLR2 complex and inhibited CXCR4-dependent, TLR2-mediated NF-κB activation. Together, these findings suggest that the new cancer-associated ligand, PAUF, may activate TLR-mediated ERK signaling to produce the protumorigenic cytokines, but inhibits TLR-mediated NF-κB signaling, thereby facilitating tumor growth and escape from innate immune surveillance.

Study of TLR3, TLR4 and TLR9 in breast carcinomas and their association with metastasis

Background

Toll-like receptors (TLRs) have garnered an extraordinary amount of interest in cancer research due to their role in tumor progression. By activating the production of several biological factors, TLRs induce type I interferons and other cytokines, which drive an inflammatory response and activate the adaptive immune system. The aim of this study was to investigate the expression and clinical relevance of TLR3, 4 and 9 in breast cancer.

Methods

The expression levels of TLR3, TLR4 and TLR9 were analyzed on tumors from 74 patients with breast cancer. The analysis was performed by immunohistochemistry.

Results

Samples of carcinomas with recurrence exhibited a significant increase in the mRNA levels of TLR3, TLR4 and TLR9. Tumors showed high expression of TLRs expression levels by cancer cells, especially TLR4 and 9. Nevertheless, a significant percentage of tumors also showed TLR4 expression by mononuclear inflammatory cells (21.6%) and TLR9 expression by fibroblast-like cells (57.5%). Tumors with high TLR3 expression by tumor cell or with high TLR4 expression by mononuclear inflammatory cells were significantly associated with higher probability of metastasis. However, tumours with high TLR9 expression by fibroblast-like cells were associated with low probability of metastasis.

Conclusions

The expression levels of TLR3, TLR4 and TLR9 have clinical interest as indicators of tumor aggressiveness in breast cancer. TLRs may represent therapeutic targets in breast cancer.

Impact of Toll-like receptor 4 polymorphisms on risk of cancer

Toll-like receptor 4 (TLR4) is one of the key immune system effectors playing the main role in recognition of viruses and bacteria. Dysregulation of the TLR4 signaling owing to single nucleotide polymorphisms (SNPs) may alter the ligand binding and balance between pro- and anti-inflammatory cytokines, thereby modulating the risk of chronic inflammation and cancer. TLR4 polymorphisms may be associated with at least nine types of cancer. The most intensively investigating TLR4 polymorphisms are Asp299Gly (rs4986790) and Thr399Ile (rs4986791). It seems to be that Asp299Gly and Thr399Ile are related to increased risk of precancerous gastric lesions, and, possibly, gastric cancer. Thr399Ile also may be connected with gallbladder cancer, and both of these polymorphisms apparently have no impact on risk of prostate cancer. However, the data about many SNPs and their associations with different types of cancer are conflicting, and further large, well-designed, comprehensive studies in various populations are necessary for solution of this problem. The short list of TLR4 SNPs for further investigation may include TLR4_896A/G (Asp299Gly, rs4986790), TLR4_1196C/T (Thr399Ile, rs4986791), Thr135Ala, TLR4_1859 G/A (rs11536858), TLR4_2032T/C (rs10116253), TLR4_2437A/G (rs1927914), TLR4_2856T/C (rs10759932), TLR4_3725 G/C (rs11536889), TLR4_7764 G/A (rs1927911), TLR4_11350G/C, TLR4_11912 G/T (rs2149356), TLR4_16649G/C (rs7873784), and TLR4_17050T/C (rs11536891).

Oxidative stress, inflammation, and cancer: how are they linked?

Extensive research during the past 2 decades has revealed the mechanism by which continued oxidative stress can lead to chronic inflammation, which in turn could mediate most chronic diseases including cancer, diabetes, and cardiovascular, neurological, and pulmonary diseases. Oxidative stress can activate a variety of transcription factors including NF-κB, AP-1, p53, HIF-1α, PPAR-γ, β-catenin/Wnt, and Nrf2. Activation of these transcription factors can lead to the expression of over 500 different genes, including those for growth factors, inflammatory cytokines, chemokines, cell cycle regulatory molecules, and anti-inflammatory molecules. How oxidative stress activates inflammatory pathways leading to transformation of a normal cell to tumor cell, tumor cell survival, proliferation, chemoresistance, radioresistance, invasion, angiogenesis, and stem cell survival is the focus of this review. Overall, observations to date suggest that oxidative stress, chronic inflammation, and cancer are closely linked.

Toll-like receptor 3 regulates angiogenesis and apoptosis in prostate cancer cell lines through hypoxia-inducible factor 1 alpha

Toll-like receptors (TLRs) recognize microbial/viral-derived components that trigger innate immune response and conflicting data implicate TLR agonists in cancer, either as protumor or antitumor agents. We previously demonstrated that TLR3 activation mediated by its agonist poly(I:C) induces antitumor signaling, leading to apoptosis of prostate cancer cells LNCaP and PC3 with much more efficiency in the former than in the second more aggressive line. The transcription factor hypoxia-inducible factor 1 (HIF-1) regulates several cellular processes, including apoptosis, in response to hypoxia and to other stimuli also in normoxic conditions. Here we describe a novel protumor machinery triggered by TLR3 activation in PC3 cells consisting of increased expression of the specific I.3 isoform of HIF-1 alpha and nuclear accumulation of HIF-1 complex in normoxia, resulting in reduced apoptosis and in secretion of functional vascular endothelial growth factor (VEGF). Moreover, we report that, in the less aggressive LNCaP cells, TLR3 activation fails to induce nuclear accumulation of HIF-1 alpha. However, the transfection of I.3 isoform of hif-1 alpha in LNCaP cells allows poly(I:C)-induced HIF-1 activation, resulting in apoptosis protection and VEGF secretion. Altogether, our findings demonstrate that differences in the basal level of HIF-1 alpha expression in different prostate cancer cell lines underlie their differential response to TLR3 activation, suggesting a correlation between different stages of malignancy, hypoxic gene expression, and beneficial responsiveness to TLR agonists.

The application of Toll like receptors for cancer therapy

Toll-like receptor (TLR) proteins play key roles in immune responses against infection. Using TLR proteins, host can recognize the conserved molecular structures found in pathogens called pathogen-associated molecular patterns (PAMPs). At the same time, some TLRs are able to detect specific host molecules, such as high-mobility group box protein 1 (HMGB1) and heat shock proteins (hsp), and lead to inflammatory responses. Thus, it has been suggested that TLRs are involved in the development of many pathogenic conditions. Recent advances in TLR-related research not only provide us with scientific information, but also show the therapeutic potential against diseases, such as autoimmune disease and cancer. In this mini review, we demonstrate how TLRs pathways could be involved in cancer development and their therapeutic application, and discuss recent patentable subjects, in particular, that are targeting this unique pathway.

Toll-like receptor signaling pathways--therapeutic opportunities

Toll-like receptors (TLRs) are transmembrane proteins acting mainly as sensors of microbial components. Triggering TLRs results in increased expression of multiple inflammatory genes, which then play a protective role against infection. However, aberrant activation of TLR signaling has a significant impact on the onset of cancer, allergy, sepsis and autoimmunity. Various adaptor proteins, including MyD88, IRAKs, TIRAP, TRIF, and TRAM, are involved in specific TLR signaling pathways. This article reviews the role of these molecules in TLR signaling, and discusses the impact of this pathway on various disease scenarios. Given their important role in infectious and non-infectious disease settings, TLRs and their signaling pathways emerge as attractive targets for therapeutics.

Squamous carcinoma cells influence monocyte phenotype and suppress lipopolysaccharide-induced TNF-alpha in monocytes

Bacteria and chronic inflammation are present in squamous cell carcinoma of the head and neck (HNSCC), but their roles in the pathogenesis of HNSCC are unclear. Our studies described here revealed that human monocytes co-cultured short term with HNSCC cells were more likely to express CD16, and CD16(+) small mononuclear cells were common in HNSCC specimens. In addition, we identified monocytes as the primary source of LPS-induced IL-6 and TNF-alpha in the monocyte-HNSCC co-cultures. Remarkably, relative to LPS-stimulated monocytes cultured alone, HNSCC cells profoundly suppressed LPS-induced TNF-alpha in monocytes, without compromising IL-6 production. High levels of cytoprotective factors like IL-6 and low levels of TNF-alpha are important for the tumor microenvironment that enables tumor cell survival, affects monocyte differentiation and may contribute to tumor colonization by bacteria. This study provides novel observations that HNSCC cells affect monocyte phenotype and function, which are relevant to the regulation of the HNSCC microenvironment.

Toll-like receptors, tissue injury, and tumourigenesis

Toll-like receptors (TLRs) belong to a class of molecules known as pattern recognition receptors, and they are part of the innate immune system, although they modulate mechanisms that impact the development of adaptive immune responses. Several studies have shown that TLRs, and their intracellular signalling components, constitute an important cellular pathway mediating the inflammatory process. Moreover, their critical role in the regulation of tissue injury and wound healing process as well as in the regulation of apoptosis is well established. However, interest in the role of these receptors in cancer development and progression has been increasing over the last years. TLRs are likely candidates to mediate effects of the innate immune system within the tumour microenvironment. A rapidly expanding area of research regarding the expression and function of TLRs in cancer cells and its association with chemoresistance and tumourigenesis, and TLR-based therapy as potential immunotherapy in cancer treatment is taking place over the last years.

Regulation of inflammation by the NF-κB pathway in ovarian cancer stem cells

PROBLEM

The NFκB pathway is a major source of pro-inflammatory cytokines, which may contribute to cancer chemoresistance. We showed that constitutive NFκB activity is characteristic of the ovarian cancer stem cells (OCSCs). The aim of this study is to determine whether the inhibition of NFκB by Eriocalyxin B (EriB) in the OCSCs may induce cell death in otherwise chemoresistant cells.

METHODS

OCSCs and mature ovarian cancer cells (mOCCs) were treated with increasing concentrations of EriB. Cell viability was measured using the Celltiter 96 assay, and caspase activity was quantified using Caspase-Glo™ assay. Cytokine levels were quantified using xMAP technology.

RESULTS

EriB decreased the percent of viable cells in all cultures tested with GI(50) of 0.5-1 μm after 48 hrs of treatment. The intracellular changes associated with EriB-induced cell death are: (i) inhibition of NF-κB activity; (ii) decreased cytokine production; (iii) activation of caspases; and (iv) down-regulation of XIAP. In addition, EriB is able to sensitize OCSCs to TNFα and FasL-mediated cell death.

CONCLUSION

Inhibition of the NFκB pathway induces cell death in the OCSCs. Because the OCSCs may represent the source of recurrence and chemoresistance, the use of NFκB inhibitors like EriB may prevent recurrence in patients with ovarian cancer.

Recent insights into the role of NF-kappaB in ovarian carcinogenesis

The NF-κBs are a family of ubiquitously expressed transcription factors that have been described to be responsible for the establishment of an inflammatory response. Studies in the past decade have also demonstrated this family's role in the initiation and progression of hematological and solid tumors. Recently, research has uncovered a specific role for NF-κBs in the development and maintenance of ovarian cancer.

Toll-like receptor (TLR) 7 and TLR8 expression on CD133+ cells in colorectal cancer points to a specific role for inflammation-induced TLRs in tumourigenesis and tumour progression

Toll-like receptor (TLR) stimulation results in activation of NF-κB, a key modulator in driving inflammation to cancer and mitogen-activated protein kinases that have been shown to recruit mitotic and cyclooxygenase-2 (COX-2) induced pathways in carcinogenesis. Here we asked whether different TLR, COX-2 and stem cell marker expression profiles in colorectal cancer (CRC) provide further evidence for this hypothesis from a clinical perspective. We analysed gene and protein expression of TLR7-TLR10, COX-2 and CD133 as a marker for colon-initiating cells in CRC patients (n=65). Gene analysis demonstrated significantly upregulated TLR7-TLR10 and COX-2 expression in CRC tumour tissues. Analysis of isolated tumour cells from primary tumours showed co-expression of TLR7 and TLR8 with CD133 and gave evidence for a subpopulation of colon cancer-initiating cells. In multivariate analyses TLR8 expression was found to be an independent prognostic factor. Persistent TLR-specific activation of NF-κB in CRC and particularly in tumour-initiating cells may thus sustain further tumour growth and progression through perpetuated signalling known from inflammatory and tissue repair mechanisms with consecutive self-renewal in pluripotent tumour cells. Activation through self-ligands or viral RNA fragments may putatively maintain this inflammatory process, suggesting a key role in cancer progression.

MTA1 coregulator regulates LPS response via MyD88-dependent signaling

Although metastasis tumor antigen 1 (MTA1) contributes to the responsiveness of macrophages to LPS, the underlying mechanism remains unknown. Here, we investigated the role of MTA1 in the regulation of expression and function of MyD88, a proximal component of NF-κB signaling. We discovered that MTA1 targets MyD88 and that MyD88 is a NF-κB-responsive gene in LPS-stimulated macrophages. We found that MTA1 is required for MyD88-dependent stimulation of NF-κB signaling and expression of proinflammatory cytokines such as IL-1β, MIP2, and TNF-α as MTA1 depletion leads to a substantial reduction in the expression of NF-κB target genes. In addition, LPS-mediated stimulation of MyD88 transcription was accompanied by an enhanced recruitment of MTA1, RNA polymerase II, and p65RelA complex to the NF-κB consensus sites in the MyD88 promoter. Interestingly, the recruitment of both MTA1 and MyD88 expression is effectively blocked by NF-κB inhibitor parthenolide. Selective knockdown of MyD88 by a dominant negative mutant of MyD88 or selective siRNA also impairs the ability of LPS to stimulate the NF-κB target genes. These findings reveal an inherent coregulatory role of MTA1 upon the expression of MyD88 and suggest that MTA1 regulation of MyD88 may constitute at least one of the mechanisms by which MTA1 stimulates LPS-induced NF-κB signaling in stimulated macrophages.

Nuclear factor kappaB transcription factors are coexpressed and convey a poor outcome in ovarian cancer

BACKGROUND

Recent work has suggested a role for nuclear factor kappaB (NF-kappaB) in the propagation of ovarian cancer cell lines, but the significance and mechanism of NF-kappaB in ovarian cancer is unknown. The authors hypothesized that the NF-kappaB pathway is over activated in aggressive ovarian cancers.

METHODS

The levels of 3 NF-kappaB transcription factors, the activating inhibitors of NF-kappaB (IkappaB) kinases, and the NF-kappaB target matrix metalloproteinase 9 (MMP9) were assessed by immunohistochemistry in specimens of ovarian cancer that were obtained at diagnosis from a cohort of 33 patients who subsequently received combined paclitaxel, cisplatin, and cyclophosphamide. Associations were made between NF-kappaB pathway proteins and outcome. The validation of coexpression was performed at the gene level in 2 independently collected cohorts of 185 and 153 ovarian cancers.

RESULTS

The presence of NF-kappaB proteins in newly diagnosed advanced ovarian cancers was established, and a potential association with overall survival was identified. Transcription factors p65 and v-rel reticuloendotheliosis viral oncogene homolog B (RelB) were coexpressed with IkappaB kinase alpha, 1 component of a key trimolecular regulatory complex. Coexpression of the NF-kappaB machinery suggested activity of NF-kappaB signaling in these ovarian tumors. A significant association of p50 with poor overall survival was observed (P = .02). MMP9 expression had the opposite association, in which patients who had tumors without MMP9 staining had the poorest prognosis (P = .01), and this association held true at the gene expression level in an independently collected cohort of 185 ovarian cancers.

CONCLUSIONS

The deregulation of NF-kappaB activity may influence outcome in women who receive standard therapy for advanced ovarian cancer. Modification of the NF-kappaB pathway may present an opportunity to improve outcome in the subset of women who have pathway activity.

Reduced expression of Toll-like receptor 4 inhibits human breast cancer cells proliferation and inflammatory cytokines secretion

Background

Tumor cell expression of Toll-like receptors (TLRs) can promote inflammation and cell survival in the tumor microenvironment. Toll-like receptor 4 (TLR4) signaling in tumor cells can mediate tumor cell immune escape and tumor progression, and it is regarded as one of the mechanisms for chronic inflammation in tumorigenesis and progression. The expression of TLR4 in human breast cancer cell line MDA-MB-231 and its biological function in the development and progression of breast cancer have not been investigated. We sought to characterize the expression of TLR1-TLR10 in the established human breast cancer cell line MDA-MB-231, and to investigate the biological roles of TLR4 in breast cancer cells growth, survival, and its potential as a target for breast cancer therapy.

Methods

TLRs mRNA and protein expressions were detected in human breast cancer cell line MDA-MB-231 by RT-PCR, real-time PCR and flow cytometry (FCM). RNA interference was used to knockdown the expression of TLR4 in MDA-MB-231. MDA-MB-231 transfected with the vector pGenesil-1 and the vector containing a scrambled siRNA were as controls. Recombinant plasmids named TLR4AsiRNA, TLR4BsiRNA and TLR4CsiRNA specific to TLR4 were transfected into human breast cancer cell line MDA-MB-231 with Lipfectamine™2000 reagent. TLR4 mRNA and protein expressions were investigated by RT-PCR, real-time PCR, FCM and immunofluorescence after silence. MTT analysis was performed to detect cell proliferation and FCM was used to detect the secretion of inflammatory cytokines in supernatant of transfected cells.

Results

The human breast cancer cell line MDA-MB-231 was found to express TLR1-TLR10 at both the mRNA and protein levels. TLR4 was found to be the highest expressed TLR in MDA-MB-231. TLR4AsiRNA, TLR4BsiRNA and TLR4CsiRNA were found to significantly inhibit TLR4 expression in MDA-MB-231 at both mRNA and protein levels as compared to vector control(vector transfected cells). TLR4AsiRNA mediated the strongest effect. Knockdown of TLR4 gene in MDA-MB-231 resulted in a dramatic reduction of breast cancer cell viability. The cytokines which were secreted by the TLR4 silenced cells, such as IL-6 and IL-8, also decreased significantly as compared with vector control. No significant difference was observed in siRNA control (Recombinant plasmid named ScrambledsiRNA transfected cells) compared to vector control.

Conclusions

These studies identified the expression levels of multiple TLRs in human breast cancer cell line MDA-MB-231 and demonstrated that knockdown of TLR4 could actively inhibit proliferation and survival of breast cancer cells. Taken together, our results suggest RNAi-directed targeting of TLR4 may be a beneficial strategy for breast cancer therapy.

Important aspects of Toll-like receptors, ligands and their signaling pathways

Due to the rapid increase of new information on the multiple roles of Toll-like receptors (TLRs), this paper reviews several main properties of TLRs and their ligands and signaling pathways. The investigation of pathogen infections in knockout mice suggests that specific TLRs play a key role in the activation of immune responses. Although the investigation of TLR biology is just beginning, a number of important findings are emerging. This review focuses on the following seven aspects of this emerging field: (a) a history of TLR and ligand studies; (b) the molecular basis of recognition by TLRs: TLR structures, pathogen-associated molecular pattern binding sites, TLR locations and functional responses; (c) cell types in TLR expression; (d) an overview of TLRs and their ligands: expression and ligands of cell-surface TLRs and of intracellular TLRs; (e) TLR-signaling pathways; (f) discussion: TLRs control of innate and adaptive systems; the trafficking of intracellular TLRs to endolysosomes; investigation of TLRs in regulating microRNA; investigation of crystal structure of TLRs with ligand binding; incidence of infectious diseases associated with single nucleotide polymorphisms (SNPs) in TLR genes; risk of cancer related to SNPs in TLR genes; TLR-ligand mediated anti-cancer effects; and TLR-ligand induced chronic inflammation and tumorigenesis; and (g) conclusions.

Expression of toll-like receptor 4 is down-regulated during progression of cervical neoplasia

Chronic infection and inflammation are among the most important factors contributing to cancer development and growth. Toll-like receptors (TLRs) are important families of pattern recognition receptors, which recognize conserved components of microbes and trigger the immune response against invading microorganisms. TLR4 is the signaling receptor for lipopolysaccharide (LPS), the endotoxic component of Gram-negative bacteria. Recent studies demonstrate that TLRs are expressed in some tumor cells, and that the expression of TLRs in these cells is associated with tumorigenesis. Cervical intraepithelial neoplasia (CIN) is a key stage in the development of cervical cancer and human papillomavirus (HPV) infection is an essential factor in cervical carcinogenesis. As the cervix is in constant contact with bacteria, especially Gram-negative bacteria, we hypothesize that TLR4-mediated bacterial stimulation may be involved in the tumorigenesis of cervical cancer. In the present study, the expression and distribution of TLR4 in CIN and cervical squamous carcinoma were investigated by immunohistochemistry. To our surprise, we observed a decrease in the expression of TLR4 during the progression of cervical neoplasia and this down-regulation of TLR4 appeared to be associated with the expression of P(16INK4A) which is a crucial marker of HPV integration into host cells. These data offer further insight regarding the association of HPV infection and TLR signaling during the carcinogenesis of cervical cancer.

Antitumor activity of polyuridylic acid in human soft tissue and bone sarcomas

BACKGROUND

The immunomodulatory properties of polyuridylic acid (PolyU) make it a promising agent in cancer immunotherapy. However, there is limited information on its direct effects on tumor cells.

MATERIALS AND METHODS

TLR8 mRNA and protein expression in soft tissue sarcoma (STS) and bone sarcoma (BS) cell lines were determined by PCR and flow cytometry, respectively. Apoptosis and proliferation assays were performed using annexin V staining and BrdU incorporation assays, respectively. A relative cell enumeration was evaluated with WST-1 reagent. Expression levels of apoptotic proteins were evaluated by Western blotting.

RESULTS

We demonstrate that PolyU treatment resulted in a significant decrease in STS and BS cell count by inducing apoptosis and inhibition of cell proliferation. All cell lines examined expressed TLR8 and the effect of PolyU was partially mediated through TLR8. Several apoptotic proteins including caspases were activated or increased in STS cells after treatment with PolyU. Administration PolyU resulted in significant growth inhibition of STS without any observable adverse effects in mouse xenograft tumor models.

CONCLUSIONS

These results elucidate the effect of PolyU in STS and BS cells and demonstrate that PolyU may be a potential therapeutic agent for STS and BS.

Expression and functional research of TLR4 in human colon carcinoma

INTRODUCTION

To verify whether human colon carcinoma cells can express Toll-like receptor 4 (TLR4) and investigate the biological function of TLR4 on human colon carcinoma cells.

METHODS

Human colon carcinoma cells SW480 was cultured with RPMI 1640 medium. The expression of TLR4 was analyzed by reverse transcription polymerase chain reaction and quantified by flow cytometry. Cell proliferation was evaluated by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide assay. The production of transforming growth factor-beta, vascular endothelial growth factor, and interleukin-8 induced by lipopolysaccharide (LPS)-the TLR4 ligand was tested by enzyme-linked immunosorbent assay. Whether mitogen-associated protein kinases and nuclear factor-kappaB (NF-kappaB) proteins were activated was analyzed by Western blot. Apoptosis was analyzed by Annenxin V/PI staining.

RESULTS

TLR4 is expressed on SW480 cells. LPS could not affect TLR4 expression and the proliferation of SW480 cells. LPS increased the phosphorylation of ERK1/2 and P38 and activated NF-kappaB. LPS promoted the production of vascular endothelial growth factor, transforming growth factor-beta, and interleukin-8. In addition, LPS induced resistance of SW480 cells to tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis. Furthermore, NF-kappaB activation was necessary for apoptosis resistance of SW480 cells induced by LPS.

CONCLUSION

TLR4 is expressed on human colon carcinoma cells and functionally active. It may play important roles in promoting immune escape of human colon carcinoma cells by inducing immunosuppressive factors and apoptosis resistance.

Triggering of TLR7 and TLR8 expressed by human lung cancer cells induces cell survival and chemoresistance

Compelling evidence suggests that inflammation, cell survival, and cancer are linked, with a central role played by NF-kappaB. Recent studies implicate some TLRs in tumor development based on their ability to facilitate tumor growth; however, to our knowledge, involvement of neither TLR7 nor TLR78 has yet been demonstrated. Here we have demonstrated expression of TLR7 and TLR8, the natural receptors for single-stranded RNA, by tumor cells in human lung cancer in situ and in human lung tumor cell lines. Stimulation with TLR7 or TLR8 agonists led to activated NF-kappaB, upregulated expression of the antiapoptotic protein Bcl-2, increased tumor cell survival, and chemoresistance. Transcriptional analysis performed on human primary lung tumor cells and TLR7- or TLR8-stimulated human lung tumor cell lines revealed a gene expression signature suggestive of chronic stimulation of tumor cells by TLR ligands in situ. Together, these data emphasize that TLR signaling can directly favor tumor development and further suggest that researchers developing anticancer immunotherapy using TLR7 or TLR8 agonists as adjuvants should take into account the expression of these TLRs in lung tumor cells.

Modulation of pattern recognition receptor-mediated inflammation and risk of chronic diseases by dietary fatty acids

Chronic inflammation is known to promote the development of many chronic diseases. Pattern recognition receptors (PRRs), Toll-like receptors (TLRs), and nucleotide-binding oligomerization domain proteins (NODs) mediate both infection-induced inflammation and sterile inflammation by recognizing pathogen- associated molecular patterns and endogenous molecules, respectively. PRR-mediated inflammation is an important determinant in altering the risk of many chronic diseases. Saturated fatty acids (SFAs) can activate PRRs, leading to enhanced expression of pro-inflammatory target gene products. However, n-3 polyunsaturated fatty acids (PUFAs) inhibit agonist-induced activation of PRRs. These results suggest that SFAs and n-3 PUFAs can reciprocally modulate PRR-mediated inflammation, and that PRRs and their downstream signaling components are molecular targets for dietary strategies to reduce chronic inflammation and subsequent risk of chronic diseases. This advancement in knowledge provides a new paradigm for understanding the mechanism by which different dietary fatty acids modify risk of chronic diseases including insulin resistance, atherosclerosis, and cancer.

Role of STAT3 decoy oligodeoxynucleotides on cell invasion and chemosensitivity in human epithelial ovarian cancer cells

Recent studies have reported that STAT3 activation is associated with poor prognosis in human epithelial ovarian cancer. STAT3 has been proposed to play an important role in ovarian cancer metastasis and chemoresistance. This mechanism, however, is still not thoroughly understood. In this study, to investigate the role of STAT3 on ovarian cancer cells, we used decoy oligodeoxynucleotide (ODN) technology to regulate STAT3 in SKOV3 and OVCAR3 cells in vitro. Cell invasive power and chemo-sensitivity were assessed in the cells transfected with STAT3 decoy ODN and control ODN. Western blot analysis was used to examine the expression of EMMPRIN, P-gp, and Akt. Results showed that STAT3 decoy ODN inhibited cancer cell invasive power and enhanced sensitivity to paclitaxel for SKOV3 and OVCAR3 cells. The mechanism involved the inhibition of EMMPRIN, P-gp, and pAkt by STAT3 decoy ODN. These three proteins were probably the target proteins of STAT3. These findings suggest that STAT3 is a key factor for ovarian cancer metastasis and chemoresistance. STAT3 decoy ODN may prove to be a beneficial therapeutic agent, especially for invasive or chemoresistant ovarian cancer.

Stem-like ovarian cancer cells can serve as tumor vascular progenitors

Neovascularization is required for solid tumor maintenance, progression, and metastasis. The most described contribution of cancer cells in tumor neovascularization is the secretion of factors, which attract various cell types to establish a microenvironment that promotes blood vessel formation. The cancer stem cell hypothesis suggests that tumors are composed of cells that may share the differentiation capacity of normal stem cells. Similar to normal stem cells, cancer stem cells (CSCs) have the capacity to acquire different phenotypes. Thus, it is possible that CSCs have a bigger role in the process of tumor neovascularization. In this study, we show the capacity of a specific population of ovarian cancer cells with stem-like properties to give rise to xenograft tumors containing blood vessels, which are lined by human CD34+ cells. In addition, when cultured in high-density Matrigel, these cells mimic the behavior of normal endothelial cells and can form vessel-like structures in 24 hours. Microscopic analysis showed extensive branching and maturation of vessel-like structures in 7 days. Western blot and flow cytometry analysis showed that this process is accompanied by the acquisition of classic endothelial markers, CD34 and VE-cadherin. More importantly, we show that this process is vascular endothelial growth factor-independent, but IKK beta-dependent. Our findings suggest that anti-angiogenic therapies should take into consideration the inherent capacity of these cells to serve as vascular progenitors.

High expression of Toll-like receptor 4/myeloid differentiation factor 88 signals correlates with poor prognosis in colorectal cancer

Background:

The Toll-like receptor (TLR) 4 signalling pathway has been shown to have oncogenic effects in vitro and in vivo. To demonstrate the role of TLR4 signalling in colon tumourigenesis, we examined the expression of TLR4 and myeloid differentiation factor 88 (MyD88) in colorectal cancer (CRC).

Methods:

The expression of TLR4 and MyD88 in 108 CRC samples, 15 adenomas, and 15 normal mucosae was evaluated by immunohistochemistry, and the correlations between their immunoscores and clinicopathological variables, including disease-free survival (DFS) and overall survival (OS), were analysed.

Results:

Compared with normal mucosae and adenomas, 20% cancers displayed high expression of TLR4, and 23% cancers showed high expression of MyD88. The high expression of TLR4 and MyD88 was significantly correlated with liver metastasis (P=0.0001, P=0.0054). In univariate analysis, the high expression of TLR4 was significantly associated with shorter OS (hazard ratio (HR): 2.17; 95% confidence interval (95% CI): 1.15–4.07; P=0.015). The high expression of MyD88 expression was significantly associated with poor DFS and OS (HR: 2.33; 95% CI: 1.31–4.13; P=0.0038 and HR: 3.03; 95% CI: 1.67–5.48; P=0.0002). The high combined expression of TLR4 and MyD88 was also significantly associated with poor DFS and OS (HR: 2.25; 95% CI: 1.27–3.99; P=0.0053 and HR: 2.97; 95% CI: 1.64–5.38; P=0.0003). Multivariate analysis showed that high expressions of TLR4 (OS: adjusted HR: 1.88; 95% CI: 0.99–3.55; P=0.0298) and MyD88 (DFS: adjusted HR: 1.93; 95% CI: 1.01–3.67; P=0.0441; OS: adjusted HR: 2.25; 95% CI: 1.17–4.33; P=0.0112) were independent prognostic factors of OS. Furthermore, high co-expression of TLR4/MyD88 was strongly associated with both poor DFS and OS.

Conclusion:

Our findings suggest that high expression of TLR4 and MyD88 is associated with liver metastasis and is an independent predictor of poor prognosis in patients with CRC.

A role for NRAGE in NF-kappaB activation through the non-canonical BMP pathway

Background

Previous studies have linked neurotrophin receptor-interacting MAGE protein to the bone morphogenic protein signaling pathway and its effect on p38 mediated apoptosis of neural progenitor cells via the XIAP-Tak1-Tab1 complex. Its effect on NF-κB has yet to be explored.

Results

Herein we report that NRAGE, via the same XIAP-Tak1-Tab1 complex, is required for the phosphorylation of IKK -α/β and subsequent transcriptional activation of the p65 subunit of NF-κB. Ablation of endogenous NRAGE by siRNA inhibited NF-κB pathway activation, while ablation of Tak1 and Tab1 by morpholino inhibited overexpression of NRAGE from activating NF-κB. Finally, cytokine profiling of an NRAGE over-expressing stable line revealed the expression of macrophage migration inhibitory factor.

Conclusion

Modulation of NRAGE expression revealed novel roles in regulating NF-κB activity in the non-canonical bone morphogenic protein signaling pathway. The expression of macrophage migration inhibitory factor by bone morphogenic protein -4 reveals novel crosstalk between an immune cytokine and a developmental pathway.

Lipopolysaccharide (LPS) increases the invasive ability of pancreatic cancer cells through the TLR4/MyD88 signaling pathway

BACKGROUND

Inflammation plays a multifaceted role in cancer progression, and NF-kappaB is one of the key factors connecting inflammation with cancer progression. We have shown that lipopolysaccharide (LPS) promotes NF-kappaB activation in colon cancer cells and pancreatic cancer cells. However, it is unclear why inflammatory stimuli can induce NF-kappaB activation in cancer cells.

METHODS

We used two human pancreatic cancer cells, Panc-1 and AsPC-1, as target cells. LPS was used as an inflammatory stimulus. To confirm the participation of TLR4/NF-kappaB signaling pathway, we used three different NF-kappaB inhibitors (PDTC, IkappaBalpha mutant, and NF-kappaB decoy ODN) and siRNAs (against TLR4, MyD88, and MMP-9). Effect of LPS on pancreatic cancer cell invasive ability was determined by Matrigel invasion assay.

RESULTS

LPS increased the invasive ability of pancreatic cancer cells, while blockade of NF-kappaB pathway decreased the LPS-dependent increased invasive ability. Blockade of TLR4 or MyD88 by siRNA also decreased the LPS-dependent increased invasive ability.

CONCLUSION

These results suggest that TLR/MyD88/NF-kappaB signaling pathway plays a significant role in connecting inflammation and cancer invasion and progression.

Opposing effects of toll-like receptor (TLR3) signaling in tumors can be therapeutically uncoupled to optimize the anticancer efficacy of TLR3 ligands

Many cancer cells express Toll-like receptors (TLR) that offer possible therapeutic targets. Polyadenylic-polyuridylic acid [poly(A:U)] is an agonist of the Toll-like receptor TLR3 that displays anticancer properties. In this study, we illustrate how the immunostimulatory and immunosuppressive effects of this agent can be uncoupled to therapeutic advantage. We took advantage of two TLR3-expressing tumor models that produced large amounts of CCL5 (a CCR5 ligand) and CXCL10 (a CXCR3 ligand) in response to type I IFN and poly(A:U), both in vitro and in vivo. Conventional chemotherapy or in vivo injection of poly(A:U), alone or in combination, failed to reduce tumor growth unless an immunochemotherapeutic regimen of vaccination against tumor antigens was included. CCL5 blockade improved the efficacy of immunochemotherapy, whereas CXCR3 blockade abolished its beneficial effects. These findings show how poly(A:U) can elicit production of a range of chemokines by tumor cells that reinforce immunostimulatory or immunosuppressive effects. Optimizing the anticancer effects of TLR3 agonists may require manipulating these chemokines or their receptors.

p52-Independent nuclear translocation of RelB promotes LPS-induced attachment

The NF-kappaB signaling pathways have a critical role in the development and progression of various cancers. In this study, we demonstrated that the small cell lung cancer cell line (SCLC) H69 expressed a unique NF-kappaB profile as compared to other cancer cell lines. The p105/p50, p100/p52, c-Rel, and RelB protein and mRNA transcripts were absent in H69 cells but these cells expressed RelA/p65. The activation of H69 cells by lipopolysaccharide (LPS) resulted in the induction of RelB and p100 expression. The treatment also induced the nuclear translocation of RelB without the processing of p100 to p52. Furthermore, LPS-induced beta1 integrin expression and cellular attachment through an NF-kappaB-dependent mechanism. Blocking RelB expression prevented the increase in the expression of beta1 integrin and the attachment of H69. Taken together, the results suggest that RelB was responsible for the LPS-mediated attachment and may play an important role in the progression of some cancers.

TLR4 signaling induced by lipopolysaccharide or paclitaxel regulates tumor survival and chemoresistance in ovarian cancer

Toll-like receptors (TLRs) expressed on immune cells trigger inflammatory responses. TLRs are also expressed on ovarian cancer (OvCa) cells, but the consequences of signaling by the TLR4/MyD88 pathway in these cells are unclear. Here, TLR4 and MyD88 expression in OvCa tissues (n=20) and cell lines (OVCAR3, SKOV3, AD10, A2780 and CP70) was evaluated by reverse transcriptase-PCR, western blots and immunohistochemistry. Cell growth, apoptosis, nuclear factor-kappaB (NF-kappaB) translocation, IRAK4 and TRIF expression and cJun phosphorylation were measured following tumor cell exposure to the TLR4 ligands, lipopolysaccharide (LPS) or paclitaxel (PTX). Culture supernatants were tested for cytokine levels. TLR4 was expressed in all tumors, tumor cell lines and normal epithelium. MyD88 was detectable in tumor tissues and in 3/5 OvCa lines but not in normal cells. In MyD88(+) SCOV3 cells, LPS or PTX binding to TLR4 induced IRAK4 activation and cJun phosphorylation, activated the NF-kappaB pathway and promoted interleukin (IL)-8, IL-6, vascular endothelial growth factor and monocyte chemotactic protein-1 production and resistance to drug-induced apoptosis. Silencing of TLR4 in SCOV3 cells with small interference RNA resulted in phosphorylated-cJun (p-cJun) downregulation and a loss of PTX resistance. In PTX-sensitive, MyD88(neg) A2780 cells, TLR4 stimulation upregulated TRIF, and TLR4 silencing eliminated this effect. Thus, TLR4/MyD88 signaling supports OvCa progression and chemoresistance, promoting immune escape.

The emergence of immunomodulation: combinatorial immunochemotherapy opportunities for the next decade

In the past decade we have witnessed important advances in the treatment of gynecological cancers and have recognized their potential immunogenicity. This has opened the door to explore immune therapy not only in HPV-induced cancers but also in ovarian and endometrial cancers. Here we will review the off-target immune effects of select chemotherapy drugs commonly used to treat gynecologic cancers and novel tools that can stimulate both the adaptive and innate immune mechanisms such as novel pleiotropic cytokines, Toll-like receptors, and powerful antibodies that can target inhibitory checkpoints, thereby activating effector cellular immune mechanisms and neutralizing suppressor cells. We will also review how existing drugs can be used for combinatorial tumor therapy.

Polymorphisms of pro-inflammatory genes and prostate cancer risk: a pharmacogenomic approach

In this paper, we consider the role of the genetics of inflammation in the pathophysiology of prostate cancer (PCa). This paper is not an extensive review of the literature, rather it is an expert opinion based on data from authors' laboratories on age-related diseases and inflammation. The aim is the detection of a risk profile that potentially allows both the early identification of individuals at risk for disease and the possible discovery of potential targets for medication. In fact, a major goal of clinical research is to improve early detection of age-related diseases, cancer included, by developing tools to move diagnosis backward in disease temporal course, i.e., before the clinical manifestation of the malady, where treatment might play a decisive role in preventing or significantly retarding the manifestation of the disease. The better understanding of the function and the regulation of inflammatory pathway in PCa may help to know the mechanisms of its formation and progression, as well as to identify new targets for the refinement of new treatment such as the pharmacogenomics approach.

Toll-like receptors 3 and 7 agonists enhance tumor cell lysis by human gammadelta T cells

Toll-like receptor (TLR) agonists are considered adjuvants in clinical trials of cancer immunotherapy. Here, we investigated the modulation of gammadelta T cell-mediated tumor cell lysis by TLR ligands. gammadelta T-cell cytotoxicity and granzyme A/B production were enhanced after pretreatment of tumor cells with TLR3 [poly(I:C)] or TLR7 ligand (imiquimod). We examined TLR3- and TLR7-expressing pancreatic adenocarcinomas, squamous cell carcinomas of head and neck and lung carcinomas. Poly(I:C) treatment of pancreatic adenocarcinomas followed by coculture with gammadelta T cells resulted in an upregulation of CD54 on the tumor cells. The interaction of CD54 and the corresponding ligand CD11a/CD18 expressed on gammadelta T cells is responsible for triggering effector function in gammadelta T cells. Moreover, treatment with imiquimod downregulated MHC class I molecules on tumor cells possibly resulting in a reduced binding affinity for inhibitory receptor NKG2A expressed on gammadelta T cells. These results indicate that TLR3 or TLR7 ligand stimulation of tumor cells enhances the cytotoxic activity of expanded gammadelta T cells of cancer patients in vitro.

Embryonic stem cells and mammary luminal progenitors directly sense and respond to microbial products

Stem cells are normally maintained in a quiescent state and proliferate only under certain conditions; however, little is known about the biological stimuli that initiate the proliferation and differentiation of stem cells. In this study, we found that functional Toll-like receptors (TLRs) are expressed on mouse embryonic stem (ES) cells and that TLR ligands stimulate ES cell proliferation and promote their hematopoietic differentiation. TLR ligands activate TLR-mediated signaling pathways, leading to the altered expression of numerous genes in ES cells. Moreover, TLR ligands efficiently stimulate the proliferation and expansion of adult stem cells and progenitors of nonhematopoietic tissues, such as mammary glands and intestine as well. We further found that mammary luminal progenitor cells (Lin(-)CD29(+)CD61(+)) express TLR4-MD2 complex and actively proliferate, resulting in the enhanced growth of mammospheres in response to TLR ligands. Thus, mouse ES cells and adult tissue-specific stem cells/progenitors directly sense and respond to microbial products, which function as a class of foreign, but biological stimuli for stem cell/progenitor proliferation. This finding expands the biological role of TLRs and has implications in understanding stem cell biology, tissue repair/homeostasis, and the role of infection and inflammation in malignant transformation.