NF-κB in solid tumors

MicroRNA-362 induces cell proliferation and apoptosis resistance in gastric cancer by activation of NF-κB signaling

Background

According to cancer-related microRNA (miRNA) expression microarray research available in public databases, miR-362 expression is elevated in gastric cancer. However, the expression and biological role of miR-362 in gastric progression remain unclear.

Methods

miR-362 expression levels in gastric cancer tissues and cell lines were determined using real-time PCR. The roles of miR-362, in promoting gastric cancer cell proliferation and apoptosis resistance, were assessed by different biological assays, such as colony assay, flow cytometry and TUNEL assay. The effect of miR-362 on NF-κB activation was investigated using the luciferase reporter assay, fluorescent immunostaining.

Results

MiR-362 overexpression induced cell proliferation, colony formation, and resistance to cisplatin-induced apoptosis in BGC-823 and SGC-7901 gastric cancer cells. MiR-362 increased NF-κB activity and relative mRNA expression of NF-κB–regulated genes, and induced nuclear translocation of p65. Expression of the tumor suppressor CYLD was inhibited by miR-362 in gastric cancer cells; miR-362 levels were inversely correlated with CYLD expression in gastric cancer tissue. MiR-362 downregulated CYLD expression by binding its 3′ untranslated region. NF-κB activation was mechanistically associated with siRNA-mediated downregulation of CYLD. MiR-362 inhibitor reversed all the effects of miR-362.

Conclusion

The results suggest that miR-362 plays an important role in repressing the tumor suppressor CYLD and present a novel mechanism of miRNA-mediated NF-κB activation in gastric cancer.

Opposing effect of EGFRWT on EGFRvIII-mediated NF-κB activation with RIP1 as a cell death switch

RIP1 is a central mediator of cell death in response to cell stress but can also mediate cell survival by activating NF-κB. Here, we show that RIP1 acts as a switch in EGFR signaling. EGFRvIII is an oncogenic mutant that does not bind ligand and is coexpressed with EGFRWT in glioblastoma multiforme (GBM). EGFRvIII recruits ubiquitin ligases to RIP1, resulting in K63-linked ubiquitination of RIP1. RIP1 binds to TAK1 and NEMO, forming an EGFRvIII-RIP1 signalosome that activates NF-κB. RIP1 is essential for EGFRvIII-mediated oncogenicity and correlates with NF-κB activation in GBM. Surprisingly, activation of EGFRWT with EGF results in a negative regulation of EGFRvIII, with dissociation of the EGFRvIII-RIP1 signalosome, loss of RIP1 ubiquitination and NF-κB activation, and association of RIP1 with FADD and caspase-8. If EGFRWT is overexpressed with EGFRvIII, the addition of EGF leads to a RIP1 kinase-dependent cell death. The EGFRWT-EGFRvIII-RIP1 interplay may regulate oncogenicity and vulnerability to targeted treatment in GBM.

Expression and significance of HMGB1, TLR4 and NF-κB p65 in human epidermal tumors

Background

High mobility group protein box 1 (HMGB1) is a DNA binding protein located in nucleus. It is released into extracellular fluid where it acts as a novel proinflammatory cytokine which interacts with Toll like receptor 4 (TLR4) to activate nuclear factor-κB (NF-κB). This sequence of events is involved in tumor growth and progression. However, the effects of HMGB1, TLR4 and NF-κB on epidermal tumors remain unclear.

Methods

Human epidermal tumor specimens were obtained from 96 patients. Immunohistochemistry was used to detect expression of HMGB1, TLR4 and NF-κB p65 in human epidermal tumor and normal skin specimens. Western blot analysis was used to detect the expression of NF-κB p65 in epithelial cell nuclei in human epidermal tumor and normal tissues.

Results

Immunohistochemistry and western blot analysis indicated a progressive but statistically significant increase in p65 expression in epithelial nuclei in benign seborrheic keratosis (SK), precancerous lesions (PCL), low malignancy basal cell carcinoma (BCC) and high malignancy squamous cell carcinoma (SCC) (P <0.01). The level of extracellular HMGB1 in SK was significantly higher than in normal skin (NS) (P <0.01), and was higher than in SCC but without statistical significance. The level of TLR4 on epithelial membranes of SCC cells was significantly higher than in SK, PCL, BCC and NS (P <0.01). There was a significant positive correlation between p65 expression in the epithelial nuclei and TLR4 expression on the epithelial cell membranes (r = 0.3212, P <0.01).

Conclusions

These findings indicate that inflammation is intensified in parallel with increasing malignancy. They also indicate that the TLR4 signaling pathway, rather than HMGB1, may be the principal mediator of inflammation in high-grade malignant epidermal tumors. Combined detection of p65 in the epithelial nuclei and TLR4 on the epithelial membranes may assist the accurate diagnosis of malignant epidermal tumors.

Role of inflammation in oral carcinogenesis (Part II): CD8, FOXP3, TNF-α, TGF-β and NF-κB expression

Due to the frequent presence of inflammation in cases of carcinoma and its use as a parameter for the assessment of tumor aggressiveness, the role of inflammation in oral carcinogenesis was investigated. This was performed by evaluating the expression of cellular markers, cytokines and nuclear transcription factors that identify the cells that participate in the antitumor defense in cases of oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC). A semi-quantitative immunohistochemical analysis was performed for the transcription factors cluster of differentiation 8 (CD8), forkhead box P3 (FOXP3), transforming growth factor (TGF)-β, tumor necrosis factor (TNF)-α and nuclear factor κ-light chain enhancer of activated B-cells (NF-κB), in cases of OED and OSCC. CD8, TGF-β, TNF-α and NF-κB participated in the processes of tumor transformation and progression. The presence of inflammatory infiltrate in cases of OED favors the transformation and invasion process when stromal TNF-α and NF-kB are overexpressed, as NF-kB activated by TNF-α during inflammation predisposes the lesion to transformation, functioning as a link between inflammation and cancer. The control of these inflammatory mediators may prevent malignant transformation in the oral cavity.

Activation of NF-kappa B signaling promotes growth of prostate cancer cells in bone

Patients with advanced prostate cancer almost invariably develop osseous metastasis. Although many studies indicate that the activation of NF-κB signaling appears to be correlated with advanced cancer and promotes tumor metastasis by influencing tumor cell migration and angiogenesis, the influence of altered NF-κB signaling in prostate cancer cells within boney metastatic lesions is not clearly understood. While C4-2B and PC3 prostate cancer cells grow well in the bone, LNCaP cells are difficult to grow in murine bone following intraskeletal injection. Our studies show that when compared to LNCaP, NF-κB activity is significantly higher in C4-2B and PC3, and that the activation of NF-κB signaling in prostate cancer cells resulted in the increased expression of the osteoclast inducing genes PTHrP and RANKL. Further, conditioned medium derived from NF-κB activated LNCaP cells induce osteoclast differentiation. In addition, inactivation of NF-κB signaling in prostate cancer cells inhibited tumor formation in the bone, both in the osteolytic PC3 and osteoblastic/osteoclastic mixed C4-2B cells; while the activation of NF-κB signaling in LNCaP cells promoted tumor establishment and proliferation in the bone. The activation of NF-κB in LNCaP cells resulted in the formation of an osteoblastic/osteoclastic mixed tumor with increased osteoclasts surrounding the new formed bone, similar to metastases commonly seen in patients with prostate cancer. These results indicate that osteoclastic reaction is required even in the osteoblastic cancer cells and the activation of NF-κB signaling in prostate cancer cells increases osteoclastogenesis by up-regulating osteoclastogenic genes, thereby contributing to bone metastatic formation.

Positional mapping and candidate gene analysis of the mouse Ccs3 locus that regulates differential susceptibility to carcinogen-induced colorectal cancer

The Ccs3 locus on mouse chromosome 3 regulates differential susceptibility of A/J (A, susceptible) and C57BL/6J (B6, resistant) mouse strains to chemically-induced colorectal cancer (CRC). Here, we report the high-resolution positional mapping of the gene underlying the Ccs3 effect. Using phenotype/genotype correlation in a series of 33 AcB/BcA recombinant congenic mouse strains, as well as in groups of backcross populations bearing unique recombinant chromosomes for the interval, and in subcongenic strains, we have delineated the maximum size of the Ccs3 physical interval to a ∼2.15 Mb segment. This interval contains 12 annotated transcripts. Sequencing of positional candidates in A and B6 identified many either low-priority coding changes or non-protein coding variants. We found a unique copy number variant (CNV) in intron 15 of the Nfkb1 gene. The CNV consists of two copies of a 54 bp sequence immediately adjacent to the exon 15 splice site, while only one copy is found in CRC-susceptible A. The Nfkb1 protein (p105/p50) expression is much reduced in A tumors compared to normal A colonic epithelium as analyzed by immunohistochemistry. Studies in primary macrophages from A and B6 mice demonstrate a marked differential activation of the NfκB pathway by lipopolysaccharide (kinetics of stimulation and maximum levels of phosphorylated IκBα), with a more robust activation being associated with resistance to CRC. NfκB has been previously implicated in regulating homeostasis and inflammatory response in the intestinal mucosa. The interval contains another positional candidate Slc39a8 that is differentially expressed in A vs B6 colons, and that has recently been associated in CRC tumor aggressiveness in humans.

Activation of nuclear factor-κB contributes to growth and aggressiveness of papillary thyroid carcinoma

Nuclear factor-κB (NF-κB) is involved in proliferation, angiogenesis, and metastasis in various malignancies; however, the role of NF-κB in papillary thyroid carcinoma (PTC) has not been fully elucidated. The purpose of this study was to elucidate the role and clinicopathological significance of the NF-κB signaling pathway in PTC. We investigated NF-κB RelA expression in 122 patients with conventional PTC by immunohistochemistry, and evaluated the correlation between RelA expression and clinicopathological parameters, including BRAF(V600E) mutation. Nuclear expression of NF-κB RelA, regardless of cytoplasmic expression, was identified in 91 of 122 PTCs (74.6%), and was more frequent in PTCs larger than 1cm (overt PTC) (P=0.001). There were significant differences in clinicopathological parameters, such as extrathyroidal extension (P=0.031), nodal metastasis (P=0.021) and BRAF(V600E) mutation (P=0.039), between NF-κB-positive and negative PTCs. Proliferation index was strongly associated with NF-κB activation (P=0.045) but not with BRAF(V600E) mutation (P=0.141). Taken together, our results suggest that NF-κB RelA activation contributes, at least in part, to tumor growth and aggressiveness of PTC after tumor transformation. The expression pattern of NF-κB may serve as a prognostic marker and a potential therapeutic target.

Effects of NFKB1 and NFKBIA gene polymorphisms on hepatocellular carcinoma susceptibility and clinicopathological features

BACKGROUND

Constitutive activation of nuclear factor (NF)-κB is frequently observed in hepatocellular carcinoma (HCC). The current study examined associations of polymorphisms within promoter regions of NFKB1 encoding NF-κB1 and NFKBIA encoding IκBα with the susceptibility of developing HCC and clinicopathological characteristics of the tumors.

METHODOLOGY AND PRINCIPAL FINDINGS

Genetic polymorphisms of NFKB1 and NFKBIA were analyzed by a real-time polymerase chain reaction (PCR) in 135 HCC patients and 520 healthy controls. The genotypic frequency of the NFKB1 -94 Ins polymorphism in HCC patients was significantly higher than that of the controls (adjusted odds ratio (AOR) = 2.23; 95% confidence interval (CI) 1.32∼3.77). No statistical significance was observed for the distribution frequency of the NFKBIA --519 C/T, -826 C/T, or -881 A/G genotype and haplotype polymorphisms between HCC patients and controls. Furthermore, female HCC patients carrying the NFKB1 -94 Ins polymorphism were associated with lower clinical stages and smaller tumor sizes.

CONCLUSIONS

Our results indicate that the NFKB1 -94 Ins promoter polymorphism increased the risk of HCC, and may be applied as a predictive factor for the clinical stage and tumor size in female HCC patients.

Differential control of growth, apoptotic activity, and gene expression in human breast cancer cells by extracts derived from medicinal herbs Zingiber officinale

The present study aimed to examine the antiproliferative potentiality of an extract derived from the medicinal plant ginger (Zingiber officinale) on growth of breast cancer cells. Ginger treatment suppressed the proliferation and colony formation in breast cancer cell lines, MCF-7 and MDA-MB-231. Meanwhile, it did not significantly affect viability of nontumorigenic normal mammary epithelial cell line (MCF-10A). Treatment of MCF-7 and MDA-MB-231 with ginger resulted in sequences of events marked by apoptosis, accompanied by loss of cell viability, chromatin condensation, DNA fragmentation, activation of caspase 3, and cleavage of poly(ADP-ribose) polymerase. At the molecular level, the apoptotic cell death mediated by ginger could be attributed in part to upregulation of Bax and downregulation of Bcl-2 proteins. Ginger treatment downregulated expression of prosurvival genes, such as NF-κB, Bcl-X, Mcl-1, and Survivin, and cell cycle-regulating proteins, including cyclin D1 and cyclin-dependent kinase-4 (CDK-4). On the other hand, it increased expression of CDK inhibitor, p21. It also inhibited the expression of the two prominent molecular targets of cancer, c-Myc and the human telomerase reverse transcriptase (hTERT). These findings suggested that the ginger may be a promising candidate for the treatment of breast carcinomas.

Role of chronic E. coli infection in the process of bladder cancer- an experimental study

Background

Bladder cancer is a common malignancy in Egypt. A history of urinary tract infection can be considered as a risk factor for bladder cancer. Escherichia coli (E. coli) infection is responsible for 70% of urinary tract infection. This study aimed to evaluate the role of chronic E. coli infection during bladder carcinogenesis. In order to achieve this aim, we investigated the histopathological changes in bladder tissue and measured the level of nuclear factor kappa p65 (NF-κBp65), Bcl-2 and interleukin 6 (IL-6) in four groups each consisting of 25 male albino rats except of control group consisting of 20 rats. The first group was normal control group, the second group was infected with E. coli, the third group was administered nitrosamine precursor, and the forth group was infected with E. coli and administered nitrosamine precursor.

Results

The histopathological examination revealed that E. coli infected group was able alone to produce some histopathological changes in bladder tissue and that nitrosamine precursor plus E. coli group showed highest incidences of urinary bladder lesions than the nitrosamine precursor group. NF-κBp65, Bcl-2 and IL-6 levels were significantly higher in nitrosamine precursor plus E. coli group than the other groups.

Conclusion

These findings suggested that urinary bladder infection by E. coli may play a major additive and synergistic role during bladder carcinogenesis.

PAX7-FKHR fusion gene inhibits myogenic differentiation via NF-kappaB upregulation

OBJECTIVE

Alveolar rhabdomyosarcomas (ARMS) are characterised by a PAX3/7-FKHR translocation, which is presumed to promote a differentiation arrest in the myogenic lineage, in which setting secondary genetic events occur, resulting in sarcomagenesis. The aim of this study was to identify the mechanism by which PAX3/7-FKHR expression results in a myogenic differentiation block, as discrete from the secondary genetic events that complete the sarcomagenic process.

METHODS

We performed a novel differential gene expression analysis comparing normal mesenchymal stem cells with previously generated non-tumorigenic mesenchymal stem cells expressing the PAX7-FKHR fusion gene, as well as with a known tumorigenic, PAX7-FKHR-expressing ARMS cell line, CW9019.

RESULTS

This novel analysis uncovered the upregulation of the NF-kappaB pathway as a function of PAX3/7-FKHR expression, but distinct from the secondary sarcomagenic process; thus implicating NF-kappaB as a mediator of the PAX3/7-FKHR differentiation block. We further show that NF-kappaB activity is upregulated in PAX7-FKHR cells when compared to parental MSCs due to upregulation of the PI3K/AKT pathway. In addition we show that NF-kappaB inhibits myogenesis via activation of cyclinD1/ cdk4 complexes, which sequester MyoD1, a key myogenic transcription factor.

CONCLUSIONS

Our results highlight the importance of the NF-kappaB pathway in myogenesis and sarcomagenesis and suggest that this pathway may be one of the potential therapeutic targets in the treatment of ARMS.

NSCLC and the alternative pathway of NF-κB: uncovering an unknown relation

Lung cancer is the leading cause of cancer-related deaths worldwide. Although our knowledge on the pathobiology of the disease has increased in the last decades, the prognosis of lung cancer patients has hardly changed. Many signaling pathways are implicated in lung carcinogenesis, but the role of the alternative pathway of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in lung cancer pathogenesis and progression has not been investigated. The aim of our study was to investigate the role of this pathway in non-small cell lung cancer (NSCLC) patients. NF-κB2 and RelB protein expression was retrospectively assessed by immunohistochemistry in tissue samples from 109 NSCLC patients. RelB and NF-κB2 protein levels differed between tumors and adjacent nonneoplastic lung parenchyma. Cytoplasmic immunoreactivity of NF-κB2 and RelB was correlated with tumor stage (p = 0.03 and p = 0.016, respectively). In addition, cytoplasmic NF-κB2 levels were related to tumor grade (p = 0.046). Expression of RelB in the cytoplasm was tumor histologic type-specific, with squamous cell carcinomas having the highest protein levels. Nuclear expression of RelB and NF-κB2 differed between tumor and nonneoplastic tissues, possibly indicating activation of the alternative pathway of NF-κB in cancer cells. Moreover, lymph node metastasis was related to nuclear NF-κB2 expression in tumor cells. The deregulation of the alternative NF-κB pathway in NSCLC could play a role in the development and progression of the disease.

Effects of NFKB1 and NFKBIA gene polymorphisms on susceptibility to environmental factors and the clinicopathologic development of oral cancer

BACKGROUND

Oral cancer, which is the fourth most common cancer in Taiwanese men, is associated with environmental carcinogens. The possibility that genetic predisposition in nuclear factor-kappa B (NF-κB)-signaling pathways activation is linked to the development of oral squamous cell carcinoma (OSCC) requires investigation. The current study examines associations between polymorphisms within promoter regions of NFKB1 encoding NF-κB1 and NFKBIA encoding IkappaBalpha (IκBα) with both the susceptibility to develop OSCC and the clinicopathological characteristics of the tumors.

METHODOLOGY/PRINCIPAL FINDINGS

Genetic polymorphisms of NFKB1 and NFKBIA were analyzed by a real-time polymerase chain reaction (real-time PCR) for 462 patients with oral cancer and 520 non-cancer controls. We found that NFKB1 -94 ATGG1/ATGG2, -94 ATGG2/ATGG2, and the combination of -94 ATGG1/ATGG2 and ATGG2/ATGG2 genotypes NFKBIA -826 T (CT+TT) and -881 G (AG+GG) allelic carriages, were more prevalent in OSCC patients than in non-cancer participants. Moreover, we found that NFKB1 or NFKBIA gene polymorphisms seem to be related to susceptibility to develop oral cancer linked to betel nut and tobacco consumption. Finally, patients with oral cancer who had at least one -519 T allele of the NFKBIA gene were at higher risk for developing distant metastasis (P<.05), compared with those patients CC homozygotes.

CONCLUSIONS

Our results suggest that NFKB1 -94 ATTG2, NFKBIA -826 T, and -881 G alleles are associated with oral carcinogenesis. The combination of NFKB1 or NFKBIA gene polymorphisms and environmental carcinogens appears related to an increased risk of oral cancer. More importantly, the genetic polymorphism of NFKBIA -519 might be a predictive factor for the distal metastasis of OSCC in Taiwanese.

Selective inhibition of NF-κB suppresses bone invasion by oral squamous cell carcinoma in vivo

Nuclear factor-κB (NF-κB) is constitutively activated in many cancers, including oral squamous cell carcinoma (OSCC), and is involved in the invasive characteristics of OSCC, such as growth, antiapoptotic activity and protease production. However, the cellular mechanism underlying NF-κB's promotion of bone invasion by OSCC is unclear. Therefore, we investigated the role of NF-κB in bone invasion by OSCC in vivo. Immunohistochemical staining of OSCC invading bone in 10 patients indicated that the expression and nuclear translocation of p65, a main subunit of NF-κB, was increased in OSCC compared with normal squamous epithelial cells. An active form of p65 phosphorylated at serine 536 was present mainly in the nucleus in not only differentiated tumor cells but also tumor-associated stromal cells and bone-resorbing osteoclasts. We next injected mouse OSCC SCCVII cells into the masseter region of C(3) H/HeN mice. Mice were treated for 3 weeks with a selective NF-κB inhibitor, NBD peptide, which disrupts the association of NF-κB essential modulator (NEMO) with IκB kinases. NBD peptide treatment inhibited TNFα-induced and constitutive NF-κB activation in SCCVII cells in vitro and in vivo, respectively. Treatment with NBD peptide decreased zygoma and mandible destruction by SCCVII cells, reduced number of osteoclasts by inhibiting RANKL expression in osteoblastic cells and SCCVII cells, increased apoptosis and suppressed the proliferation of SCCVII cells. Taken together, our data clearly indicate that inhibition of NF-κB is useful for inhibiting bone invasion by OSCC.

Potential role of LMP2 as tumor-suppressor defines new targets for uterine leiomyosarcoma therapy

Although the majority of smooth muscle neoplasms found in the uterus are benign, uterine leiomyosarcoma (LMS) is extremely malignant, with high rates of recurrence and metastasis. We earlier reported that mice with a homozygous deficiency for LMP2, an interferon (IFN)-γ-inducible factor, spontaneously develop uterine LMS. The IFN-γ pathway is important for control of tumor growth and invasion and has been implicated in several cancers. In this study, experiments with human and mouse uterine tissues revealed a defective LMP2 expression in human uterine LMS that was traced to the IFN-γ pathway and the specific effect of JAK-1 somatic mutations on the LMP2 transcriptional activation. Furthermore, analysis of a human uterine LMS cell line clarified the biological significance of LMP2 in malignant myometrium transformation and cell cycle, thus implicating LMP2 as an anti-tumorigenic candidate. This role of LMP2 as a tumor suppressor may lead to new therapeutic targets in human uterine LMS.

CAPC negatively regulates NF-κB activation and suppresses tumor growth and metastasis

CAPC, also known as LRRC26, is expressed in normal prostate and salivary gland. We developed a mAb to CAPC and used it to characterize the protein and study its function. CAPC protein was detected in normal prostate and salivary gland, in several human breast cancer cell lines and in the prostate cancer cell line LNCaP. Knockdown of CAPC by siRNA in LNCaP cells enhanced anchorage-independent growth in soft agar. Conversely, overexpression of CAPC in MDA-231 breast cancer cells and A431 epidermoid cancer cells inhibited growth in soft agar and tumorigenesis in nude mice, and suppressed the metastasis of MDA-231 cells to the lung. Overexpression of CAPC downregulated NF-κB activity and its target genes, including GM-CSF (CSF2), CXCL1, IL8 and LTB1. It also suppressed genes encoding the serine protease mesotrypsin (PRSS3) and cystatin SN (CST1). CAPC expressing tumors showed a decrease in the number of proliferating cells and a large increase in ECM. The role of CAPC in the suppression of tumor growth and metastasis may be through its alteration of the tumor microenvironment.

The role of intracellular protein O-glycosylation in cell adhesion and disease

Post-translational protein modification, including phosphorylation, is generally quick and reversible, facilitating rapid biologic adjustments to altered cellular physiologic demands. In addition to protein phosphorylation, other post-translational modifications have been identified. Intracellular protein O-glycosylation, the addition of the simple sugar O-linked N-acetylglucosamine (O-GlcNAc) to serine/threonine residues, is a relatively recently identified post-translational modification that has added to the complexity by which protein function is regulated. Two intracellular enzymes, O-GlcNAc transferase and O-GlcNAcase, catalyze the addition and removal, respectively, of O-GlcNAc to serine and threonine side-chain hydroxyl groups. Numerous proteins, including enzymes, transcription factors, receptors and structural proteins have been shown to be modified by intracellular O-glycosylation. In this review, the mechanism and relevance of O-GlcNAc protein modification are discussed in the context of cell adhesion and several representative diseases.

Rhein inhibits angiogenesis and the viability of hormone-dependent and -independent cancer cells under normoxic or hypoxic conditions in vitro

Hypoxia is a hallmark of solid tumors, including breast cancer, and the extent of tumor hypoxia is associated with treatment resistance and poor prognosis. Considering the limited treatment of hypoxic tumor cells and hence a poor prognosis of breast cancer, the investigation of natural products as potential chemopreventive anti-angiogenic agents is of paramount interest. Rhein (4,5-dihydroxyanthraquinone-2-carboxylic acid), the primary anthraquinone in the roots of Cassia alata L., is a naturally occurring quinone which exhibits a variety of biologic activities including anti-cancer activity. However, the effect of rhein on endothelial or cancer cells under hypoxic conditions has never been delineated. Therefore, the aim of this study was to investigate whether rhein inhibits angiogenesis and the viability of hormone-dependent (MCF-7) or -independent (MDA-MB-435s) breast cancer cells in vitro under normoxic or hypoxic conditions. Rhein inhibited vascular endothelial growth factor (VEGF(165))-stimulated human umbilical vein endothelial cell (HUVEC) tube formation, proliferation and migration under normoxic and hypoxic conditions. In addition, rhein inhibited in vitro angiogenesis by suppressing the activation of phosphatidylinositol 3-kinase (PI3K), phosphorylated-AKT (p-AKT) and phosphorylated extracellular signal-regulated kinase (p-ERK) but showed no inhibitory effects on total AKT or ERK. Rhein dose-dependently inhibited the viability of MCF-7 and MDA-MB-435s breast cancer cells under normoxic or hypoxic conditions, and inhibited cell cycle in both cell lines. Furthermore, Western blotting demonstrated that rhein inhibited heat shock protein 90alpha (Hsp90α) activity to induce degradation of Hsp90 client proteins including nuclear factor-kappa B (NF-κB), COX-2, and HER-2. Rhein also inhibited the expression of hypoxia-inducible factor-1 alpha (HIF-1α), vascular endothelial growth factor (VEGF(165)), epidermal growth factor (EGF), and the phosphorylation of inhibitor of NF-κB (I-κB) under normoxic or hypoxic conditions. Taken together, these data indicate that rhein is a promising anti-angiogenic compound for breast cancer cell viability and growth. Therefore, further studies including in vivo and pre-clinical need to be performed.

Curcumin analog GO-Y030 is a novel inhibitor of IKKβ that suppresses NF-κB signaling and induces apoptosis

Curcumin is a dietary constituent with tumor-suppressing potential, inhibiting various pathways involved in carcinogenesis. However, because of its low bioavailability, the use of curcumin in in vivo trials has been limited. To overcome this problem, we synthesized more than 50 analogs and identified a monoketone analog, GO-Y030, which has a 30-fold higher potential to suppress tumor cell growth compared with curcumin. We investigated the inhibitory effect of GO-Y030 on NF-κB activation. In thyroid, pancreatic cancers and cholangiocarcinoma cells, in which NF-κB is activated, NF-κB activation was suppressed to 8-62% of the control value following treatment with 1 μM GO-Y030, an effect comparable to that of 10 μM curcumin. Direct inhibition of IKKβ kinase activity and suppression of nuclear translocation of the NF-κB p65 subunit were observed. The 50% growth inhibition concentrations of GO-Y030 ranged from one-11th to one-14th of those of curcumin. GO-Y030 also induced cell death comparable to that induced by curcumin but at a 10-fold lower concentration. In pancreatic and thyroid cancer cells, the growth-inhibitory effect of GO-Y030 was 4- and 15-fold greater, respectively, than that of curcumin. GO-Y030 was a much stronger inducer of apoptosis compared with curcumin. The enhanced potency of GO-Y030 may make it more useful than curcumin, which suffers from low bioavailability. GO-Y030 is a good lead compound for the development of useful compounds for practical cancer chemotherapy.

Stem cell marker olfactomedin 4: critical appraisal of its characteristics and role in tumorigenesis

Olfactomedin 4 (OLFM4), a member of the olfactomedin domain-containing proteins, is a glycoprotein with molecular weight of approximately 64 kDa. The protein is a "robust marker" of Lgr5+ stem cells and has been localised to mitochondria, nuclei and cell membranes. The bulk of OLFM4 exists in a polymeric form which is held together by disulfide bonds and carbohydrate interactions. Earlier studies revealed that the protein binds to lectins and cadherins, and facilitates cell-cell adhesion. Recent data demonstrated that the protein possesses several hallmarks of carcinogenesis. OLFM4 has also been purported to be an inducible resistance factor to apoptotic stimuli such as radiation and anticancer drugs. Here, we review its synonyms and classification, gene structure, protein structure, intracellular and tissue distribution, adhesive and antiapoptotic; mitotic; migratory and cell cycle regulatory characteristics. We also critically evaluate recent advances in understanding of the transcriptional regulation of OLFM4 and its upstream signalling pathways with special emphasis on carcinogenesis and outline future perspectives in the field.

Characterization and mechanistic studies of a novel melanoma-targeting construct containing IκBa for specific inhibition of nuclear factor-κB activity

The transcription factor nuclear factor-κB (NF-κB) is a central mediator of growth and homeostasis for both normal and neoplastic cells. IκBα is the natural intracellular inhibitor of NF-κB and can effectively complex with and thereby inhibit the biologic activity and translocation of NF-κB to the nucleus. We designed a fusion protein designated IκBα/scFvMEL composing of human IκBα and the single-chain antibody scFvMEL, targets melanoma gp240 antigen. Cells treated with IκBα/scFvMEL before irradiation showed specifically inhibition of both constitutive and radiation-induced NF-κB activity on gp240 antigen-positive A375M cells. Pretreatment of A375M cells with IκBα/scFvMEL significantly sensitized melanoma cells to ionizing radiation assessed using a clonogenic survival assay. Mechanistic studies showed that IκBα/scFvMEL, when exogenously added to A375M cells, could be coimmunoprecipitated with the p65 subunit of NF-κB. IκBα/scFvMEL inhibited in a time and/or dose-dependent manner of tumor necrosis factor α- or radiation-induced NF-κB activity in vitro. IκBα/scFvMEL was also shown to specifically inhibit the translocation of the NF-κB p65 subunit to the cell nucleus and NF-κB-mediated gene transcription. Further, initial studies showed that mice bearing well-established A375M xenografts were treated (intravenously) with IκBα/scFvMEL and showed a significant suppression of tumor growth. We also observed a decrease in levels of Bcl-2 and Bcl-XL signaling events downstream of NF-κB in the tumor model. These studies demonstrate for the first time that tumor cell-targeted delivery of IκBα may be beneficial for the treatment of melanoma when combined with standard anticancer therapies such as radiation.

Targeting inflammatory pathways for tumor radiosensitization

Although radiation therapy (RT) is an integral component of treatment of patients with many types of cancer, inherent and/or acquired resistance to the cytotoxic effects of RT is increasingly recognized as a significant impediment to effective cancer treatment. Inherent resistance is mediated by constitutively activated oncogenic, proliferative and anti-apoptotic proteins/pathways whereas acquired resistance refers to transient induction of proteins/pathways following radiation exposure. To realize the full potential of RT, it is essential to understand the signaling pathways that mediate inducible radiation resistance, a poorly characterized phenomenon, and identify druggable targets for radiosensitization. Ionizing radiation induces a multilayered signaling response in mammalian cells by activating many pro-survival pathways that converge to transiently activate a few important transcription factors (TFs), including nuclear factor kappa B (NF-κB) and signal transducers and activators of transcription (STATs), the central mediators of inflammatory and carcinogenic signaling. Together, these TFs activate a wide spectrum of pro-survival genes regulating inflammation, anti-apoptosis, invasion and angiogenesis pathways, which confer tumor cell radioresistance. Equally, radiation-induced activation of pro-inflammatory cytokine network (including interleukin (IL)-1β, IL-6 and tumor necrosis factor-α) has been shown to mediate symptom burden (pain, fatigue, local inflammation) in cancer patients. Thus, targeting radiation-induced inflammatory pathways may exert a dual effect of accentuating the tumor radioresponse and reducing normal tissue side-effects, thereby increasing the therapeutic window of cancer treatment. We review recent data demonstrating the pivotal role played by inflammatory pathways in cancer progression and modulation of radiation response.

The neem limonoids azadirachtin and nimbolide induce cell cycle arrest and mitochondria-mediated apoptosis in human cervical cancer (HeLa) cells

Limonoids from the neem tree (Azadirachta indica) have attracted considerable research attention in recent years owing to their potent antioxidant and anti-proliferative effects. The present study was designed to investigate the cellular and molecular mechanisms by which azadirachtin and nimbolide exert cytotoxic effects in the human cervical cancer (HeLa) cell line. Both azadirachtin and nimbolide significantly suppressed the viability of HeLa cells in a dose-dependent manner by inducing cell cycle arrest at G0/G1 phase accompanied by p53-dependent p21 accumulation and down-regulation of the cell cycle regulatory proteins cyclin B, cyclin D1 and PCNA. Characteristic changes in nuclear morphology, presence of a subdiploid peak and annexin-V staining pointed to apoptosis as the mode of cell death. Increased generation of reactive oxygen species with decline in the mitochondrial transmembrane potential and release of cytochrome c confirmed that the neem limonoids transduced the apoptotic signal via the mitochondrial pathway. Altered expression of the Bcl-2 family of proteins, inhibition of NF-kappaB activation and over-expression of caspases and survivin provide compelling evidence that azadirachtin and nimbolide induce a shift of balance toward a pro-apoptotic phenotype. Antioxidants such as azadirachtin and nimbolide that can simultaneously arrest the cell cycle and target multiple molecules involved in mitochondrial apoptosis offer immense potential as anti-cancer therapeutic drugs.

Intracardiac injection of AdGRK5-NT reduces left ventricular hypertrophy by inhibiting NF-kappaB-dependent hypertrophic gene expression

Several studies underline the role of the transcription factor NF-κB in the development of left cardiac hypertrophy (LVH). We have demonstrated recently that the RGS homology domain within the amino terminus of GRK5 (GRK5-NT) is able to inhibit NF-κB transcription activity and its associated phenotypes. The aim of this study was to evaluate the ability of GRK5-NT to regulate LVH through the inhibition of NF-κB both in vitro and in vivo. In cardiomyoblasts, GRK5-NT inhibits phenylephrine-induced transcription of both NF-κB and atrial natriuretic factor promoters, assessed by luciferase assay, thus confirming a role for this protein in the regulation of cardiomyocyte hypertrophy. In vivo, we explored 2 rat models of LVH, the spontaneously hypertensive rat and the normotensive Wistar Kyoto rat exposed to chronic administration of phenylephrine. Intracardiac injection of an adenovirus encoding for GRK5-NT reduces cardiac mass in spontaneously hypertensive rats and prevents the development of phenylephrine-induced LVH in Wistar Kyoto rats. This associates with inhibition of NF-κB signaling (assessed by NF-κB levels), transcriptional activity and phenotypes (fibrosis and apoptosis). Such phenomenon is independent from hemodynamic changes, because adenovirus encoding for GRK5-NT did not reduce blood pressure levels in spontaneously hypertensive rats or in Wistar Kyoto rats. In conclusion, our study supports the regulation of LVH based on the GRK5-NT inhibition of the NF-κB transduction signaling.

KappaB-Ras is a nuclear-cytoplasmic small GTPase that inhibits NF-kappaB activation through the suppression of transcriptional activation of p65/RelA

NF-κB is an important transcription factor involved in various biological responses, including inflammation, cell differentiation, and tumorigenesis. κB-Ras was identified as an IκB-interacting small GTPase and is reported to disturb cytokine-induced NF-κB activation. In this study, we established that κB-Ras is a novel type of nuclear-cytoplasmic small GTPase that mainly binds to GTP, and its localization seemed to be regulated by its GTP/GDP-binding state. Unexpectedly, the GDP-binding form of the κB-Ras mutant exhibited a more potent inhibitory effect on NF-κB activation, and this inhibitory effect seemed to be due to suppression of the transactivation of a p65/RelA NF-κB subunit. κB-Ras suppressed phosphorylation at serine 276 on the p65/RelA subunit, resulting in decreased interaction between p65/RelA and the transcriptional coactivator p300. Interestingly, the GDP-bound κB-Ras mutant exhibited higher interactive affinity with p65/RelA and inhibited the phosphorylation of p65/RelA more potently than wild-type κB-Ras. Taken together, these findings suggest that the GDP-bound form of κB-Ras in cytoplasm suppresses NF-κB activation by inhibiting its transcriptional activation.

Nuclear factor-κB expression is predictive of overall survival in patients with cutaneous melanoma

Nuclear factor (NF)- κB is one of the most important transcription factors that plays a crucial role in the regulation of a wide spectrum of genes involved in modulating the cell cycle, apoptosis, cell growth, angiogenesis, inflammation and the tissue invasiveness of highly malignant cells. NF-κB activity has been found to be constitutively elevated in a number of human tumors from either a haematological or solid origin, such as melanomas. In several studies, NF-κB activation was shown to be an adverse prognostic factor, and in melanoma it was proposed as an event that promotes tumor progression. This study aimed to evaluate whether NF-κB activation in tumor tissues, assessed by the expression of the NF-κB p65 subunit, has an effect on the survival of melanoma patients. The expression of NF-κB was immunohistochemically investigated, and the correlation with survival was analyzed. Furthermore, the immunostaining for p53 and survivin was evaluated, and the relationship of these apoptotic and anti-apoptotic factors with NF-κB expression was analyzed. Kaplan-Meier analysis showed that patients with low levels of NF-κB in the nuclei of tumor cells had a significantly longer survival compared to those with high levels. Multivariate analysis confirmed the predictive value of nuclear NF-κB, showing that its expression maintains significance after the model was adjusted using clinicopathological factors. The results demonstrate the correlation of NF-κB p65 nuclear staining with the disease-specific 5-year survival of melanoma patients and suggest that nuclear NF-κB p65 may be promising as an early independent prognostic factor in patients with primary cutaneous melanoma.

Role of NF-kappaB in thyroid cancer

Thyroid cancer is the most common neoplasia of the endocrine system and accounts for approximately 1% of all newly diagnosed cancer cases. Its incidence has rapidly grown over the past few decades. Although most thyroid carcinomas are of the well-differentiated papillary histology, and respond well to treatment with surgical resection followed by radioactive iodine ablation, tumors with more aggressive phenotype, such as follicular, poorly differentiated, anaplastic, and medullary cancers, lead to almost 1500 patient deaths annually. Therefore, understanding molecular mechanisms that regulate the biology of these carcinomas could be helpful to identify new molecules acting as novel targets for therapeutic intervention. NF-kappaB has been recently shown to play an important role in thyroid cancer for its ability to control the proliferative and the anti-apoptotic signaling pathways of thyroid neoplastic cells. Oncogenic proteins RET/PTC, RAS and BRAF, that are involved in many aspects of thyroid carcinogenesis, can induce NF-kappaB activation in papillary, follicular, and medullary thyroid carcinomas, while constitutive de-regulated NF-kappaB activity has been found in anaplastic thyroid carcinomas. A number of NF-kappaB inhibitors have been demonstrated to induce anti-proliferative effects and/or massive apoptosis, especially in combination with radio- or chemo-therapy. The results obtained suggest that targeting NF-kappaB could be a promising strategy for advanced thyroid cancer treatment.

Inhibition of nuclear factor-kappa B differentially affects thyroid cancer cell growth, apoptosis, and invasion

Background

Nuclear factor-κB (NF-κB) is constitutively activated in many cancers and plays a key role in promoting cell proliferation, survival, and invasion. Our understanding of NF-κB signaling in thyroid cancer, however, is limited. In this study, we have investigated the role of NF-κB signaling in thyroid cancer cell proliferation, invasion, and apoptosis using selective genetic inhibition of NF-κB in advanced thyroid cancer cell lines.

Results

Three pharmacologic inhibitors of NF-κB differentially inhibited growth in a panel of advanced thyroid cancer cell lines, suggesting that these NF-κB inhibitors may have off-target effects. We therefore used a selective genetic approach to inhibit NF-κB signaling by overexpression of a dominant-negative IκBα (mIκBα). These studies revealed decreased cell growth in only one of five thyroid cancer cell lines (8505C), which occurred through a block in the S-G2/M transition. Resistance to TNFα-induced apoptosis was observed in all cell lines, likely through an NF-κB-dependent mechanism. Inhibition of NF-κB by mIκBα sensitized a subset of cell lines to TNFα-induced apoptosis. Sensitive cell lines displayed sustained activation of the stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK) pathway, defining a potential mechanism of response. Finally, NF-κB inhibition by mIκBα expression differentially reduced thyroid cancer cell invasion in these thyroid cancer cell lines. Sensitive cell lines demonstrated approximately a two-fold decrease in invasion, which was associated with differential expression of MMP-13. MMP-9 was reduced by mIκBα expression in all cell lines tested.

Conclusions

These data indicate that selective inhibition of NF-κB represents an attractive therapeutic target for the treatment of advanced thyroid. However, it is apparent that global regulation of thyroid cancer cell growth and invasion is not achieved by NF-κB signaling alone. Instead, our findings suggest that other important molecular processes play a critical role in defining the extent of NF-κB function within cancer cells.

Up regulation of GW112 Gene by NF kappaB promotes an antiapoptotic property in gastric cancer cells

To clarify the regulatory mechanism of GW112 gene expression, 5'-flanking region of the human GW112 gene was isolated and characterized in the present study. 5'-RACE analysis showed a single transcription start site, which is located 142 nucleotides upstream of the translation initiation site. Transient transfection studies with serial deletion constructs and close examination of the sequences identified a putative NF kappaB binding sequence between -442 and -430, which could be responsible for efficient expression of the GW112 gene. Indeed, GW112 gene was found to be regulated by NF kappaB signals including overexpressed p65 and I kappaB alpha, IKK inhibitor, and proteasome inhibitor. Binding of NF kappaB to its putative site was confirmed by EMSA and ChIP assays. These results suggest that NF kappaB is an essential regulatory factor for GW112 transcription. Based on this finding, we next confirmed that inhibition of GW112 expression could induce apoptosis in the presence of cytotoxic agent in gastric cancer cells. Furthermore, knocking-down or overexpression of GW112 gene in gastric cancer cells demonstrated that GW112 has an antiapoptotic property against the cytotoxic agents-induced apoptosis. Taken together, these results suggest that GW112 could be an important mediator in NF kappaB-dependent tumorigenesis of digestive tract tissues.

NF-kappaB-inhibited acute myeloid leukemia cells are rescued from apoptosis by heme oxygenase-1 induction

Despite high basal NF-kappaB activity in acute myeloid leukemia (AML) cells, inhibiting NF-kappaB in these cells has little or no effect on inducing apoptosis. We previously showed that heme oxygenase-1 (HO-1) underlies this resistance of AML to tumor necrosis factor-induced apoptosis. Here, we describe a mechanism by which HO-1 is a silent antiapoptotic factor only revealed when NF-kappaB is inhibited, thus providing a secondary antiapoptotic mechanism to ensure AML cell survival and chemoresistance. We show that inhibition of NF-kappaB increased HO-1 expression in primary AML cells compared with that of nonmalignant cells. In addition, we observed this suppressed HO-1 level in AML cells compared with CD34(+) nonmalignant control cells. Using chromatin immunoprecipitation assay and small interfering RNA knockdown, we showed that the NF-kappaB subunits p50 and p65 control this suppression of HO-1 in AML cells. Finally, we showed that inhibition of HO-1 and NF-kappaB in combination significantly induced apoptosis in AML cells but not in noncancerous control cells. Thus, NF-kappaB inhibition combined with HO-1 inhibition potentially provides a novel therapeutic approach to treat chemotherapy-resistant forms of AML.

Oligomannurarate sulfate blocks tumor growth by inhibiting NF-kappaB activation

AIM

JG3, a novel marine-derived oligosaccharide, significantly inhibits angiogenesis and tumor metastasis by blocking heparanase activity. It also arrests tumor growth, an effect that is not fully explained by its anti-heparanase activity. Here we sought to identify the mechanisms underlying JG3-mediated inhibition of tumor growth.

METHODS

Heparanase expression was assessed by RT-PCR and Western blotting. NF-kappaB activation status was determined using immunofluorescence, Western blotting, DNA-binding and transcription-activity assays. The effect of JG3 on upstream components of the NF-kappaB pathway and on selected transcription factors were monitored by Western blotting. The antitumor effect of JG3 and its relation to NF-kappaB activation were evaluated using four different tumor xenograft models.

RESULTS

We found that JG3 effectively inhibited NF-kappaB activation independent of heparanase expression. Our results indicate that JG3 inactivated NF-kappaB by interfering with the activation of upstream components of the NF-kappaB pathway without generally affecting the nuclear translocation of transcription factors. Further, in vivo studies demonstrated that JG3 effectively arrested the growth of tumors derived from cell lines in which NF-kappaB was constitutively active (BEL-7402 liver carcinoma and MDA-MB-435s breast carcinoma), but did not affect the growth of tumors derived from NF-kappaB-negative cell lines (SGC-7901 gastric cancer and HO-8910 ovarian carcinoma).

CONCLUSION

Our data indicate that NF-kappaB mediates the JG3-induced arrest of tumor growth. These results define a new mechanism of action of JG3 and highlight the potential for JG3 as a promising lead molecule in cancer therapy.

Characterization of a major colon cancer susceptibility locus (Ccs3) on mouse chromosome 3

Treatment of mice with the carcinogen azoxymethane (AOM) induces a number of lesions in the colon, including hyperplastic lesions, as well adenomas and carcinomas in situ. Inbred strains of mice show different responses to AOM-induced carcinogenesis. A/J mice are highly susceptible and develop a greater number of hyperplastic lesions and tumors (15-70 tumors per mouse) than resistant C57BL/6J mice (0-6 tumors per mouse). Susceptibility to AOM-induced tumors segregates as a co-dominant trait in (A x B6)F1 hybrids. Using a set of 23 AcB and BcA recombinant congenic mouse strains derived from A/J (susceptible) and B6 (resistant) parents, we observed that the number of hyperplastic lesions and tumors induced by AOM was under different genetic controls in AcB/BcA strains. The multiplicity of AOM-induced tumors is controlled by a major locus that we have mapped on the distal portion of chromosome 3, to which we have given the temporary designation colon cancer susceptibility locus 3 (Ccs3). B6 and A/J alleles at Ccs3 are associated with resistance and susceptibility, respectively. Haplotype analysis in key informative AcB/BcA strains restricts the size of the Ccs3 locus to a 14 Mb segment that contains 94 annotated genes. The expression level of all these genes in normal colon has been established by transcript profiling with microarrays, and has led to the identification of a subset of positional candidates that are expressed at high levels in this tissue. The 4q and 1p human chromosomal segments sharing syntenic homology with the mouse Ccs3 segment are known to be associated with inflammatory bowel diseases and colorectal tumors in humans, suggesting that the study of the mouse Ccs3 locus may help further the pathogenesis of these human conditions.

Relationship between NFKB1 -94 insertion/deletion ATTG polymorphism and susceptibility of cervical squamous cell carcinoma risk

BACKGROUND

A very high expression of nuclear factor-kappa B protein (nuclear p50, encoded by NFKB1) in high-grade squamous intraepithelial lesion and invasive cancers has been observed. The aim of this study was to determine whether the functional NFKB1 -94 insertion/deletion ATTG polymorphism (rs28362491) is associated with cervical squamous cell carcinoma (CSCC).

MATERIALS AND METHODS

PCR-polyacrylamide gel electrophoresis method was used to genotype the NFKB1 -94 insertion/deletion ATTG polymorphism in 233 women with CSCC and 365 ethnicity-matched healthy control women. The genotyping method was confirmed by the DNA sequencing analysis.

RESULTS

The frequency of ATTG(2)/ATTG(2) genotype and ATTG(2) allele in the CSCC patients was significantly higher than that of controls, indicating that the -94 insertion/deletion ATTG polymorphism in NFKB1 promoter was associated with CSCC [P = 0.001, odds ratio (OR) = 2.560, 95% confidence interval (CI) 1.459-4.492 and P = 0.001, OR = 1.493, 95% CI 1.168-1.908, respectively]. Results of stratified analyses revealed that this polymorphism is associated with younger age (< or =35 years) and positive parametrial invasion but not with tumor differentiation, high clinical stage or lymph node status.

CONCLUSION

Our results indicate that the functional NFKB1 -94 insertion/deletion ATTG polymorphism is associated with CSCC, especially with younger age (< or =35 years) and positive parametrial invasion of CSCC patients.

Inhibition of IkB kinase and NF-kappaB by a novel synthetic compound SK 2009

The NF-kappaB family of transcription factors plays an important role in determining cell survival during immune, inflammatory, and stress responses. NF-kappaB activity is frequently deregulated in human cancers and is implicated in the resistance of tumor cells to diverse anticancer agents. We studied the effects of novel analogs of precursors of the natural product simplactone (A) on the activity of IkB kinase and NF-kappaB. Screening of six compounds for the ability to inhibit TNF-induced NF-kappaB activity revealed that compound SK2009 was the most potent of these compounds in suppressing NF-kappaB activation in KBM-5 leukemic cells. Further characterization of SK2009 indicates that this newly synthesized molecule can suppress TNF-induced IkappaBalpha kinase activation and inhibit the expression of three NF-kappaB-dependent gene products, cyclin D1, Bcl-2, and VEGF, in these cells.

Death-associated protein kinase (DAPK) and signal transduction: regulation in cancer

Death-associated protein kinase (DAPK) is a pro-apoptotic serine/threonine protein kinase that is dysregulated in a wide variety of cancers. The mechanism by which this occurs has largely been attributed to promoter hypermethylation, which results in gene silencing. However, recent studies indicate that DAPK expression can be detected in some cancers, but its function is still repressed, suggesting that DAPK activity can be subverted at a post-translational level in cancer cells. This review will focus on recent data describing potential mechanisms that may alter the expression, regulation or function of DAPK.

A new assay format for NF-kappaB based on a DNA triple helix and a fluorescence resonance energy transfer

Herein we report a feasibility study for a new concept to detect DNA binding protein NF-kappaB based on a DNA triple helix formation in combination with a fluorescence resonance energy transfer (FRET). The new principle avoids expensive antibodies and radioactivity and might have implications for assays of other DNA binding proteins.

The receptor interacting protein 1 inhibits p53 induction through NF-kappaB activation and confers a worse prognosis in glioblastoma

Nuclear factor-kappaB (NF-kappaB) activation may play an important role in the pathogenesis of cancer and also in resistance to treatment. Inactivation of the p53 tumor suppressor is a key component of the multistep evolution of most cancers. Links between the NF-kappaB and p53 pathways are under intense investigation. In this study, we show that the receptor interacting protein 1 (RIP1), a central component of the NF-kappaB signaling network, negatively regulates p53 tumor suppressor signaling. Loss of RIP1 from cells results in augmented induction of p53 in response to DNA damage, whereas increased RIP1 level leads to a complete shutdown of DNA damage-induced p53 induction by enhancing levels of cellular mdm2. The key signal generated by RIP1 to up-regulate mdm2 and inhibit p53 is activation of NF-kappaB. The clinical implication of this finding is shown in glioblastoma, the most common primary malignant brain tumor in adults. We show that RIP1 is commonly overexpressed in glioblastoma, but not in grades II and III glioma, and increased expression of RIP1 confers a worse prognosis in glioblastoma. Importantly, RIP1 levels correlate strongly with mdm2 levels in glioblastoma. Our results show a key interaction between the NF-kappaB and p53 pathways that may have implications for the targeted treatment of glioblastoma.

Functional polymorphism of the NFKB1 gene promoter is related to the risk of dilated cardiomyopathy

Background

Previous studies in experimental and human heart failure showed that nuclear factor kappa B (NF-κB) is chronically activated in cardiac myocytes, suggesting an important involvement of NF-κB in the cardiac remodeling process. A common insertion/deletion (-94 insertion/deletion ATTG, rs28362491) located between two putative key promoter regulatory elements in the NFKB1 gene was identified which seems to be the first potential functional NFKB1 genetic variation. The main goal of the present investigation was to investigate the NFKB1 -94 insertion/deletion ATTG polymorphism in relation to risk of dilated cardiomyopathy (DCM).

Methods

A total of 177 DCM patients and 203 control subjects were successfully investigated. The NFKB1 -94 insertion/deletion ATTG polymorphism was genotyped by using PCR-PAGE.

Results

Genotype frequency of NFKB1 -94 insertion/deletion ATTG polymorphism in DCM patients was significantly different from that in control subjects (P = 0.015) and the ATTG₂ carrier (ATTG₁/ATTG₂ + ATTG₂/ATTG₂) was susceptible to DCM.

Conclusion

Our data suggested that NFKB1 -94 insertion/deletion ATTG polymorphism is associated with DCM.

Glycogen synthase kinase-3 inhibition disrupts nuclear factor-kappaB activity in pancreatic cancer, but fails to sensitize to gemcitabine chemotherapy

Background

Aberrant activation NF-kappaB has been proposed as a mechanism of drug resistance in pancreatic cancer. Recently, inhibition of glycogen synthase kinase-3 has been shown to exert anti-tumor effects on pancreatic cancer cells by suppressing NF-kappaB. Consequently, we investigated whether inhibition of GSK-3 sensitizes pancreatic cancer cells to the chemotherapeutic agent gemcitabine.

Methods

GSK-3 inhibition was achieved using the pharmacological agent AR-A014418 or siRNA against GSK-3 alpha and beta isoforms. Cytotoxicity was measured using a Sulphorhodamine B assay and clonogenic survival following exposure of six different pancreatic cancer cell lines to a range of doses of either gemcitabine, AR-A014418 or both for 24, 48 and 72 h. We measured protein expression levels by immunoblotting. Basal and TNF-alpha induced activity of NF-kappaB was assessed using a luciferase reporter assay in the presence or absence of GSK-3 inhibition.

Results

GSK-3 inhibition reduced both basal and TNF-alpha induced NF-kappaB luciferase activity. Knockdown of GSK-3 beta reduced nuclear factor kappa B luciferase activity to a greater extent than GSK-3 alpha, and the greatest effect was seen with dual knockdown of both GSK-3 isoforms. GSK-3 inhibition also resulted in reduction of the NF-kappaB target proteins XIAP, Bcl-X_L, and cyclin D1, associated with growth inhibition and decreased clonogenic survival. In all cell lines, treatment with either AR-A014418, or gemcitabine led to growth inhibition in a dose- and time-dependent manner. However, with the exception of PANC-1 where drug synergy occurred with some dose schedules, the inhibitory effect of combined drug treatment was additive, sub-additive, or even antagonistic.

Conclusion

GSK-3 inhibition has anticancer effects against pancreatic cancer cells with a range of genetic backgrounds associated with disruption of NF-kappaB, but does not significantly sensitize these cells to the standard chemotherapy agent gemcitabine. This lack of synergy might be context or cell line dependent, but could also be explained on the basis that although NF-kappaB is an important mediator of pancreatic cancer cell survival, it plays a minor role in gemcitabine resistance. Further work is needed to understand the mechanisms of this effect, including the potential for rational combination of GSK3 inhibitors with other targeted agents for the treatment of pancreatic cancer.

Ginger extract (Zingiber officinale) has anti-cancer and anti-inflammatory effects on ethionine-induced hepatoma rats

OBJECTIVE

To evaluate the effect of ginger extract on the expression of NFkappaB and TNF-alpha in liver cancer-induced rats.

METHODS

Male Wistar rats were randomly divided into 5 groups based on diet: i) control (given normal rat chow), ii) olive oil, iii) ginger extract (100mg/kg body weight), iv) choline-deficient diet + 0.1% ethionine to induce liver cancer and v) choline-deficient diet + ginger extract (100mg/kg body weight). Tissue samples obtained at eight weeks were fixed with formalin and embedded in paraffin wax, followed by immunohistochemistry staining for NFkappaB and TNF-alpha.

RESULTS

The expression of NFkappaB was detected in the choline-deficient diet group, with 88.3 +/- 1.83% of samples showing positive staining, while in the choline-deficient diet supplemented with ginger group, the expression of NFkappaB was significantly reduced, to 32.35 +/- 1.34% (p<0.05). In the choline-deficient diet group, 83.3 +/- 4.52% of samples showed positive staining of TNF-alpha, which was significantly reduced to 7.94 +/- 1.32% (p<0.05) when treated with ginger. There was a significant correlation demonstrated between NFkappaB and TNF-alpha in the choline-deficient diet group but not in the choline-deficient diet treated with ginger extract group.

CONCLUSION

In conclusion, ginger extract significantly reduced the elevated expression of NFkappaB and TNF-alpha in rats with liver cancer. Ginger may act as an anti-cancer and anti-inflammatory agent by inactivating NFkappaB through the suppression of the pro-inflammatory TNF-alpha.

NEMO-binding domain peptide inhibits proliferation of human melanoma cells

Melanoma is the most aggressive form of skin cancer, it originates from melanocytes and its incidence has increased in the last decade. Recent advances in the understanding of the underlying biology of the progression of melanoma have identified key signalling pathways that are important in promoting melanoma tumourigenesis, thus providing dynamic targets for therapy. One such important target identified in melanoma tumour progression is the Nuclear Factor-kappaB (NF-kappaB) pathway. In vitro studies have shown that NF-kappaB binding is constitutively elevated in human melanoma cultures compared to normal melanocytes. It has been found that a short cell-permeable peptide spanning the IKK-beta NBD, named NBD peptide, disrupted the association of NEMO with IKKs in vitro and blocked TNFalpha-induced NF-kappaB activation in vivo. In the present study we investigated the effect of the NBD peptide on NF-kappaB activity and survival of A375 human melanoma cells. We found that NBD peptide is able to inhibit the proliferation of A375 cells, which present constitutively elevated NF-kappaB levels. Inhibition of cell proliferation by NBD peptide was associated with direct inhibition of constitutive NF-kappaB DNA-binding activity and induction of apoptosis by activation of caspase-3 as confirmed by the cleavage and consequently inactivation of poly (ADP ribose) polymerase (PARP-1) known as the best marker of this process.

Dehydroxymethylepoxyquinomicin, a novel nuclear Factor-kappaB inhibitor, enhances antitumor activity of taxanes in anaplastic thyroid cancer cells

Nuclear factor kappaB (NF-kappaB), as an antiapoptotic factor, crucially affects the outcomes of cancer treatments, being one of the major culprits of resistance to chemotherapy. In this study, we investigated whether dehydroxymethylepoxyquinomicin (DHMEQ), a novel NF-kappaB inhibitor, can enhance antitumor activities of taxanes in anaplastic thyroid cancer (ATC) cells. Taxanes induced NF-kappaB activation in ATC cells, which could compromise the therapeutic effect of the drugs. However, DHMEQ, by inhibiting the nuclear translocation of NF-kappaB, completely suppressed the DNA binding capacities of NF-kappaB and lowered the levels of nuclear NF-kappaB protein. Compared with single treatment (either taxane or DHMEQ), the combined treatment strongly potentiated apoptosis, confirmed by cell survival assay; Western blotting for poly (ADP-ribose) polymerase, caspase 3, X-linked inhibitor of apoptosis, and survivin; and flow cytometry for annexin V. Furthermore, we also demonstrate for the first time that the combined treatment showed significantly greater inhibitory effect on tumor growth in a nude mice xenograft model. These findings suggest that taxanes are able to induce NF-kappaB activation in ATC cells, which could attenuate antitumor activities of the drugs, but inhibition of NF-kappaB by DHMEQ creates a chemosensitive environment and greatly enhances apoptosis in taxanes-treated ATC cells in vitro and in vivo. Thus, DHMEQ may emerge as an attractive therapeutic strategy to enhance the response to taxanes in ATCs.

NF-KappaB expression correlates with apoptosis and angiogenesis in clear cell renal cell carcinoma tissues

Background

Clear cell renal cell carcinoma (ccRCC) is the most frequently encountered tumor in the adult kidney. Many factors are known to take part in the development and progression of this tumor. Nuclear factor kappa B (NF-κB) is a family of the genes that includes five members acting in events such as inflammation and apoptosis. In this study, the role of NF-κB (p50 subunit) in ccRCC and its relation to angiogenesis and apoptosis were investigated.

Methods

Formalin-fixed and paraffin embedded tissue blocks from 40 patients with ccRCC were studied. Expressions of NF-κB (p50), VEGF, EGFR, bc1-2 and p53 were detected immunohistochemically. The relationship of NF-κB with these markers and clinicopathological findings were evaluated.

Results

The expression of NF-κB was detected in 35 (85%), VEGF in 37 (92.5%), EGFR in 38 (95%), bc1-2 in 33 (82.5%) and p53 in 13 (32.5%) of 40 ccRCC patients. Statistical analyses revealed a significant relation between NF-κB expression and VEGF (p = 0.001), EGFR (p = 0.004), bc1-2 (p = 0.010) and p53 (p = 0.037). There was no significant correlation between NF-κB and such parameters as tumor grade, stage, age and sex.

Conclusion

The results of this study indicated that in ccRCC cases NF-κB was associated with markers of angiogenesis and apoptosis such as VEGF, EGFR, bc1-2 and p53. In addition, the results did not only suggest a close relationship between NF-κB and VEGF, EGFR, bc1-2 and p53 in ccRCC, but also indicate that NF-κB was a potential therapeutic target in the treatment of ccRCC resistant to chemotherapy.

The nuclear factor-kappaB pathway controls the progression of prostate cancer to androgen-independent growth

Typically, the initial response of a prostate cancer patient to androgen ablation therapy is regression of the disease. However, the tumor will progress to an "androgen-independent" stage that results in renewed growth and spread of the cancer. Both nuclear factor-kappaB (NF-kappaB) expression and neuroendocrine differentiation predict poor prognosis, but their precise contribution to prostate cancer progression is unknown. This report shows that secretory proteins from neuroendocrine cells will activate the NF-kappaB pathway in LNCaP cells, resulting in increased levels of active androgen receptor (AR). By blocking NF-kappaB signaling in vitro, AR activation is inhibited. In addition, the continuous activation of NF-kappaB signaling in vivo by the absence of the IkappaBalpha inhibitor prevents regression of the prostate after castration by sustaining high levels of nuclear AR and maintaining differentiated function and continued proliferation of the epithelium. Furthermore, the NF-kappaB pathway was activated in the ARR(2)PB-myc-PAI (Hi-myc) mouse prostate by cross-breeding into a IkappaBalpha(+/-) haploid insufficient line. After castration, the mouse prostate cancer continued to proliferate. These results indicate that activation of NF-kappaB is sufficient to maintain androgen-independent growth of prostate and prostate cancer by regulating AR action. Thus, the NF-kappaB pathway may be a potential target for therapy against androgen-independent prostate cancer.

ABINs inhibit EGF receptor-mediated NF-kappaB activation and growth of EGF receptor-overexpressing tumour cells

The epidermal growth factor receptor (EGFR) is frequently overexpressed in various tumours of epidermal origin and is held responsible for tumourigenicity and tumour persistence. Increased nuclear factor (NF)-kappaB activity has been suggested to be involved in the malignant behaviour of EGFR-overexpressing cells. However, the mechanisms that regulate EGF-induced NF-kappaB activation are still largely unknown. Here we show that EGF can induce NF-kappaB-dependent gene expression independently from IkappaBalpha degradation or p100 processing in EGFR-overexpressing HEK293T cells. Moreover, EGF-induced NF-kappaB activation could be inhibited by overexpression of ABINs, which were previously identified as intracellular inhibitors of tumour necrosis factor, interleukin-1 and lipopolysaccharide-induced NF-kappaB activation. Knockdown of ABIN-1 by RNA interference boosted the NF-kappaB response upon EGF stimulation. The C-terminal ubiquitin-binding domain containing region of ABINs was crucial and sufficient for NF-kappaB inhibition. Adenoviral gene transfer of ABINs reduced constitutive NF-kappaB activity as well as the proliferation of EGFR-overexpressing A431 and DU145 human carcinoma cells. Altogether, these results demonstrate an important role for an ABIN-sensitive non-classical NF-kappaB signalling pathway in the proliferation of EGFR-overexpressing tumour cells, and indicate a potential use for ABIN gene therapy in the treatment of cancer.