Tumor necrosis factor and cancer, buddies or foes?

The role of chronic inflammation in obesity-associated cancers

There is a strong relationship between metabolism and immunity, which can become deleterious under conditions of metabolic stress. Obesity, considered a chronic inflammatory disease, is one example of this link. Chronic inflammation is increasingly being recognized as an etiology in several cancers, particularly those of epithelial origin, and therefore a potential link between obesity and cancer. In this review, the connection between the different factors that can lead to the chronic inflammatory state in the obese individual, as well as their effect in tumorigenesis, is addressed. Furthermore, the association between obesity, inflammation, and esophageal, liver, colon, postmenopausal breast, and endometrial cancers is discussed.

Female heterozygous (+/fa) Zucker rats as a novel leptin-related mammary carcinogenesis model

The homozygous mutant fatty Zucker rat (fa/fa) is the prominent model for the research of obesity, one of the most well-known risk factor of postmenopausal mammary cancer. But the usage as a mammary gland carcinogenesis model is considered to be restricted due to the hypoplasia of mammary gland. In the present study, to find the validity of heterozygous mutant (+/fa) lean Zucker rats as a new leptin-related mammary carcinogenesis model, we examined whether the number of terminal end buds of mammary gland, the serum biochemistry, leptin concentration in serum and adipose tissue are changed in 7-week-old female +/+, +/fa and fa/fa rats, and whether these changes and leptin, TNF-α and VEGF mRNA expression in adipose tissue of +/+ and +/fa rats are influenced by 10% corn oil diet for 5 weeks. We confirmed that mild hyperleptinemia was more pronounced in 7-week-old +/fa as compared with wild type (+/+) and hypoplasia of mammary glands characterized by fewer numbers of terminal end buds in fa/fa was not observed in +/fa. With 10% corn oil diet, leptin mRNA expression in adipose tissue showed increasing tendency both in +/fa and +/+. Comparing with +/+, adipose tissue in +/fa treated with 10% corn oil diet was found to be significantly increased in the concentration of leptin protein and tended to be elevated expression of TNF-α mRNA. These results suggest that +/fa with 10% corn oil diet may be a useful model for investigation of the participation of leptin and TNF-α in mammary gland carcinogenesis.

Creating a tumor-resistant microenvironment: cell-mediated delivery of TNFα completely prevents breast cancer tumor formation in vivo

Here, we provide the necessary proof of concept, that it is possible to metabolically create a non-permissive or "hostile" stromal microenvironment, which actively prevents tumor engraftment in vivo. We developed a novel genetically engineered fibroblast cell line that completely prevents tumor formation in mice, with a 100% protection rate. No host side effects were apparent. This could represent a viable cellular strategy for preventing and treating a variety of human cancers. More specifically, we examined the autocrine and paracrine effects of the cellular delivery of TNFα on breast cancer tumor growth and cancer metabolism. For this purpose, we recombinantly overexpressed TNFα in human breast cancer cells (MDA-MB-231) or human immortalized fibroblasts (hTERT-BJ1). Our results directly show that TNFα functions as a potent tumor suppressor. Remarkably, TNFα-expressing breast cancer cells were viable, without any significant increases in their basal apoptotic rate. However, after 4 weeks post-implantation, TNFα-expressing breast cancer cells failed to form any tumors in xenografted mice (0 tumors/10 injections), ultimately conferring 100% protection against tumorigenesis. Similarly, TNFα-overexpressing fibroblasts were also viable, without any increases in apoptosis. Significantly, complete tumor suppression was obtained by co-injecting TNFα expressing stromal fibroblasts with human breast cancer cells, indicating that paracrine cell-mediated delivery of TNFα can also prevent tumor engraftment and growth (0 tumors/10 injections). Mechanistically, TNFα induced autophagy and mitochondrial dysfunction in both epithelial cancer cells and stromal fibroblasts, preventing energy transfer from the tumor microenvironment, likely "starving" the cancer cells to death. In addition, via qRT-PCR analysis of MDA-MB-231 cells, we observed that TNFα mediated the upregulation of gene transcripts associated with inflammation and senescence [IL-1-β, IL-6, IL-8, MCP-1, COX-2, p21(WAF1/CIP1)] and downregulated known tumor-promoting genes (collagen VI and MMP2). Recombinant overexpression of TNFα receptor(s) in MDA-MB-231 cells also significantly reduced tumor growth, but was not as effective as the TNFα ligand itself in preventing tumor growth. Thus, we propose that stromal cell-mediated delivery of TNFα to human tumors [using transfected fibroblasts or mesenchymal stem cells (hMSCs)] may be a novel and effective strategy for the prevention and treatment of human cancers.

Paradoxical roles of tumour necrosis factor-alpha in prostate cancer biology

Tumour necrosis factor (TNF) is a pleiotropic cytokine with dual roles in cancer biology including prostate cancer (PCa). On the one hand, there is evidence that it stimulates tumour angiogenesis, is involved in the initiation of PCa from an androgen-dependent to a castrate resistant state, plays a role in epithelial to mesenchymal plasticity, and may contribute to the aberrant regulation of eicosanoid pathways. On the other hand, TNF has also been reported to inhibit neovascularisation, induce apoptosis of PCa cells, and stimulate antitumour immunity. Much of the confusion surrounding its seemingly paradoxical roles in cancer biology stems from the dependence of its effects on the biological model within which TNF is investigated. This paper will address some of these issues and also discuss the therapeutic implications.

A comparative study of adhesion of melanoma and breast cancer cells to blood and lymphatic endothelium

BACKGROUND

Lymphovascular invasion (LVI) is an important step in the metastatic cascade; tumor cell migration and adhesion to blood and lymphatic vessels is followed by invasion through the vessel wall and subsequent systemic spread. Although primary breast cancers and melanomas have rich blood vascular networks, LVI is predominately lymphatic in nature. Whilst the adhesion of tumor cells to blood endothelium has been extensively investigated, there is a paucity of information on tumor cell adhesion to lymphatic endothelium.

METHODS AND RESULTS

Breast cancer (MDA-MB-231 and MCF7) and melanoma (MeWo and SKMEL-30) cell adhesion to lymphatic (hTERT-LEC and HMVEC dLy Neo) and blood (HUVEC and hMEC-1) endothelial cells were assessed using static adhesion assays. The effect of inflammatory conditions, tumor necrosis factor-α (TNF-α) stimulation of endothelial and tumor cells, on the adhesive process was also examined. In addition, the effects of TNF-α stimulation on tumor cell migration was investigated using haplotaxis (scratch wound) assays. Breast cancer and melanoma cells exhibited higher levels of adhesion to blood compared to lymphatic endothelial cells (p<0.001). TNF-α stimulation of endothelial cells, or of tumor cells alone, did not significantly alter tumor-endothelial cell adhesion or patterns. When both tumor and endothelial cells were stimulated with TNF-α, a significant increase in adhesion was observed (p<0.01), which was notably higher in the lymphatic cell models (p<0.001). TNF-α-stimulation of all tumor cell lines significantly increased their migration rate (p<0.01).

CONCLUSIONS

Results suggest that metastasis resultant from lymphatic vessel-tumor cell adhesion may be modulated by cytokine stimulation, which could represent an important therapeutic target in breast cancer and melanoma.

Targeting truncated retinoid X receptor-α by CF31 induces TNF-α-dependent apoptosis

A truncated version of retinoid X receptor-α, tRXR-α, promotes cancer cell survival by activating the phosphoinositide 3-kinase (PI3K)/AKT pathway. However, targeting the tRXR-α-mediated survival pathway for cancer treatment remains to be explored. We report here our identification of a new natural product molecule, CF31, a xanthone isolated from Cratoxylum formosum ssp. pruniflorum, and the biologic evaluation of its regulation of the tRXR-α-mediated PI3K/AKT pathway. CF31 binds RXR-α and its binding results in inhibition of RXR-α transactivation. Through RXR-α mutational analysis and computational studies, we show that Arg316 of RXR-α, known to form salt bridges with certain RXR-α ligands, such as 9-cis-retinoic acid (9-cis-RA), is not required for the antagonist effect of CF31, showing a distinct binding mode. Evaluation of several CF31 analogs suggests that the antagonist effect is mainly attributed to an interference with Leu451 of helix H12 in RXR-α. CF31 is a potent inhibitor of AKT activation in various cancer cell lines. When combined with TNF-α, it suppresses TNF-α activation of AKT by inhibiting TNF-α-induced tRXR-α interaction with the p85α regulatory subunit of PI3K. CF31 inhibition of TNF-α activation of AKT also results in TNF-α-dependent activation of caspase-8 and apoptosis. Together, our results show that CF31 is an effective converter of TNF-α signaling from survival to death by targeting tRXR-α in a unique mode and suggest that identification of a natural product that targets an RXR-mediated cell survival pathway that regulates PI3K/AKT may offer a new therapeutic strategy to kill cancer cells.

Higher serum levels of tumour necrosis factor and its soluble receptors are associated with ovarian tumours

INTRODUCTION

Tumour necrosis factor (TNF) and its soluble receptors type 1 (sTNF-R1) and type 2 (sTNF-R2) have been suggested as key mediators between apoptosis and cancer cell progression. The aim was to examine concentrations of the parameters in the serum of women with ovarian tumour and in the fluid from ovarian cysts of women with serous cystadenoma.

MATERIAL AND METHODS

The study included 125 women with ovarian tumours. As a control, sera were obtained from 70 healthy female volunteers. Concentrations of TNF, sTNF-R1 and sTNF-R2 were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Significant increases of TNF, sTNF-R1 and sTNF-R2 were found in the serum of women with ovarian tumour in comparison to the control (p < 0.0001). The highest levels of all studied parameters were observed in women with ovarian cancer. In the ovarian cyst fluid the concentrations of the evaluated parameters increased significantly as compared to the serum (p < 0.0001).

CONCLUSIONS

Our data showed changes in regulatory mechanisms of apoptosis in women with ovarian tumours which are associated with increased concentrations of all studied factors. Serum estimated TNF and especially sTNF-R may be used as complementary diagnostic markers in patients with ovarian tumours.

Myoblasts inhibit prostate cancer growth by paracrine secretion of tumor necrosis factor-α

PURPOSE

Myoblasts can form muscle fibers after transplantation. Therefore, they are envisioned as a treatment for urinary incontinence after radical prostatectomy. However, to our knowledge the safety of this treatment and the interaction of myoblasts with any remaining neighboring cancer are unknown. We investigated the interactions between myoblasts and prostate carcinoma cells in vitro and in vivo.

MATERIALS AND METHODS

Myoblasts isolated from the rectus abdominis were used in a series of co-culture experiments with prostate cancer cells and subcutaneously co-injected in vivo. Cell proliferation, cell cycle arrest and apoptosis of cancer in co-culture with myoblasts were assessed. Tumor volume and metastasis formation were evaluated in a mouse model. Tissue specific markers were assessed by immunohistochemistry, fluorescence activated cell sorting analysis, Western blot and real-time quantitative polymerase chain reaction.

RESULTS

Myoblasts in proximity to tumor provided paracrine tumor necrosis factor-α to their microenvironment, decreasing the tumor growth of all prostate cancer cell lines examined. Co-culture experiments revealed induction of cell cycle arrest, tumor death by apoptosis and increased myoblast differentiation. This effect was largely blocked by tumor necrosis factor-α inhibition. The same outcome was noted in a mouse model, in which co-injected human myoblasts also inhibited the tumor growth and metastasis formation of all prostate cancer cell lines evaluated.

CONCLUSIONS

Myoblasts restrict prostate cancer growth and limit metastasis formation by paracrine tumor necrosis factor-α secretion in vitro and in vivo.

The effect of sulindac, a non-steroidal anti-inflammatory drug, attenuates inflammation and fibrosis in a mouse model of chronic pancreatitis

BACKGROUND

Chronic pancreatitis is characterized by progressive fibrosis, pain and loss of exocrine and endocrine functions. The long-standing chronic pancreatitis and its associated pancreatic fibrosis are the most common pathogenic events involved in human pancreatic carcinogenesis, but the therapeutic strategies to chronic pancreatitis and the chemoprevention of pancreatic carcinogenesis are very limited.

METHODS

We investigated the effect of sulindac, a non-steroidal anti-inflammatory drug (NSAID), on inhibition of chronic pancreatitis in a caerulein induced chronic pancreatitis mouse model.

RESULTS

Sulindac significantly reduced the severity of chronic pancreatitis including the extent of acini loss, inflammatory cell infiltration and stromal fibrosis. The protein expression of phosphorylation of MEK/ERK was inhibited in the chronic pancreatic tissues by sulindac treatment as measured by Western blot assay. The levels of inflammatory cytokines including TNF-α and MCP-1 were also significantly decreased with sulindac treatment, as well as the expression of TGF-β, PDGF-β, SHH and Gli in the chronic pancreatic tissue detected by qPCR assay and confirmed by western blot assay. The activation of pancreatic satellet cells was also inhibited by sulindac as measured by the activity of α-smooth muscle actin (α-SMA) in the pancreatic tissue of chronic pancreatitis.

CONCLUSIONS

Sulindac is a promising reagent for the treatment of chronic pancreatitis via inhibition of inflammatory cell infiltration and stromal fibrosis, the inhibitory effect of sulindac on chronic pancreatitis may through targeting the activation ERK/MAPK signaling pathway.

Gambogic acid inhibits TNF-α-induced invasion of human prostate cancer PC3 cells in vitro through PI3K/Akt and NF-κB signaling pathways

AIM

To investigate the mechanisms underlying the inhibitory effect of gambogic acid (GA) on TNF-α-induced metastasis of human prostate cancer PC3 cells in vitro.

METHODS

TNF-α-mediated migration and invasion of PC3 cells was examined using migration and invasion assays, respectively. NF-κB transcriptional activity and nuclear translocation were analyzed with luciferase reporter gene assays, immunofluorescence assays and Western blots. The ability of p65 to bind the promoter of Snail, an important mesenchymal molecular marker, was detected using a chromatin immunoprecipitation (ChIP) assay. After treatment with Snail-specific siRNA, the expression of invasiveness-associated genes was measured using quantitative real-time PCR and Western blot.

RESULTS

GA significantly inhibited the viability of PC3 cells at 1-5 μmol/L, but did not produce cytotoxic effect at the concentrations below 0.5 μmol/L. GA (0.125-0.5 μmol/L) dose-dependently inhibited the migration and invasion of PC3 cells induced by TNF-α (10 ng/mL). Moreover, the TNF-α-mediated activation of phosphatidylinositol-3-OH kinase/protein kinase B (PI3K/Akt) and NF-κB pathways was suppressed by GA (0.5 μmol/L). Furthermore, this anti-invasion effect of GA was associated with regulation of Snail. Snail expression was significantly down-regulated by treatment with GA (0.5 μmol/L) in the TNF-α-stimulated PC3 cells.

CONCLUSION

GA inhibits TNF-α-induced invasion of PC3 cells via inactivation of the PI3K/Akt and NF-κB signaling pathways, which may offer a novel approach for the treatment of human prostate cancer.

MUC1 contributes to BPDE-induced human bronchial epithelial cell transformation through facilitating EGFR activation

Although it is well known that epidermal growth factor receptor (EGFR) is involved in lung cancer progression, whether EGFR contributes to lung epithelial cell transformation is less clear. Mucin 1 (MUC1 in human and Muc1 in animals), a glycoprotein component of airway mucus, is overexpressed in lung tumors; however, its role and underlying mechanisms in early stage lung carcinogenesis is still elusive. This study provides strong evidence demonstrating that EGFR and MUC1 are involved in bronchial epithelial cell transformation. Knockdown of MUC1 expression significantly reduced transformation of immortalized human bronchial epithelial cells induced by benzo[a]pyrene diol epoxide (BPDE), the active form of the cigarette smoke (CS) carcinogen benzo(a)pyrene (BaP)s. BPDE exposure robustly activated a pathway consisting of EGFR, Akt and ERK, and blocking this pathway significantly increased BPDE-induced cell death and inhibited cell transformation. Suppression of MUC1 expression resulted in EGFR destabilization and inhibition of the BPDE-induced activation of Akt and ERK and increase of cytotoxicity. These results strongly suggest an important role for EGFR in BPDE-induced transformation, and substantiate that MUC1 is involved in lung cancer development, at least partly through mediating carcinogen-induced activation of the EGFR-mediated cell survival pathway that facilitates cell transformation.

Kinome-wide functional genomics screen reveals a novel mechanism of TNFα-induced nuclear accumulation of the HIF-1α transcription factor in cancer cells

Hypoxia-inducible factor-1 (HIF-1) and its most important subunit, HIF-1α, plays a central role in tumor progression by regulating genes involved in cancer cell survival, proliferation and metastasis. HIF-1α activity is associated with nuclear accumulation of the transcription factor and regulated by several mechanisms including modulation of protein stability and degradation. Among recent advances are the discoveries that inflammation-induced cytokines and growth factors affect protein accumulation of HIF-1α under normoxia conditions. TNFα, a major pro-inflammatory cytokine that promotes tumorigenesis is known as a stimulator of HIF-1α activity. To improve our understanding of TNFα-mediated regulation of HIF-1α nuclear accumulation we screened a kinase-specific siRNA library using a cell imaging–based HIF-1α-eGFP chimera reporter assay. Interestingly, this systematic analysis determined that depletion of kinases involved in conventional TNFα signaling (IKK/NFκB and JNK pathways) has no detrimental effect on HIF-1α accumulation. On the other hand, depletion of PRKAR2B, ADCK2, TRPM7, and TRIB2 significantly decreases the effect of TNFα on HIF-1α stability in osteosarcoma and prostate cancer cell lines. These newly discovered regulators conveyed their activity through a non-conventional RELB-depended NFκB signaling pathway and regulation of superoxide activity. Taken together our data allow us to conclude that TNFα uses a distinct and complex signaling mechanism to induce accumulation of HIF-1α in cancer cells. In summary, our results illuminate a novel mechanism through which cancer initiation and progression may be promoted by inflammatory cytokines, highlighting new potential avenues for fighting this disease.

Vitamin E restriction in the diet enhances phagocytic activation by dichloroacetate and trichloroacetate in mice

The effects of a vitamin E-restricted diet on the induction of phagocytic activation by dichloroacetate (DCA) and trichloroacetate (TCA) was investigated. Groups of B6C3F1 male mice were either kept on standard diet (Std diet group) or diet that had the vitamin provided only by its natural ingredients (Low-E diet group). The animals in each diet group were administered 77 mg of DCA or TCA/ kg/day, or 5 ml/kg water (controls), by gavage, for 13 weeks. Thereafter, peritoneal lavage cells (PLC) were assayed for superoxide anion (SA), tumor necrosis factor (TNF)-α, and myeloperoxidase (MPO), as well as for the activities of the anti-oxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px). SA and TNFα production, as well as MPO, SOD, CAT and GSH-Px activities were significantly increased in the cells from the Low-E diet group treated with the compounds as compared with cells from hosts in the Std-diet group that received the corresponding treatments. The results indicate that consumption of a Vitamin E-restricted diet enhances the induction of phagocytic activation by DCA and TCA, a mechanism that was previously suggested to be an initial adaptive/protective response against the compounds long-term effects.

Ferulic acid is nephrodamaging while gallic acid is renal protective in long term treatment of chronic kidney disease

BACKGROUNDS & AIMS

The long term therapeutic effect of ferulic acid (FA) and gallic acid (GA) in treatment of chronic kidney disease (CKD) has been lacking.

METHODS

Doxorubicin (DR, Adriamycin)-induced CKD rat model was established for this study.

RESULTS

DR significantly reduced levels of serum albumin, GOT, GPT, RBC, TNF-α, and urinary creatinine and elevated serum cholesterol, TG, BUN, creatinine, uric acid, WBC, platelet count, and IL-6. In DRCKD rats, FA and GA significantly increased kidney weight and glomerular volume. FA reduced glomerular filtration rate but GA did not. FA enhanced more collagen deposition than GA in renal cortex and glomeruli. Both FA and GA showed crucial hyperlipidemic activity. The inhibitory effects of FA and GA on MMP-2 were very comparable. GA suppressed MMP-2 more effectively than FA in DRCKD rats. Both FA and GA induced SOD elevation and MDA elimination. In DRCKD rats, Western blot analysis indicated that FA further up-regulated CD34, α-SMA, tissue pDGFR, p-PDGFR, and TGF-β; and down-regulated p-PI3K, and p-Akt. Since both PDGF-BB and TGF-β are considered to induce kidney prefibrosis stage, GA was proved to be more beneficial in this regard.

CONCLUSIONS

GA tends to protect the CKD while FA is not recommended for the long term CKD therapy.

Evaluation of antitumor effects following tumor necrosis factor-α gene delivery using nanobubbles and ultrasound

The antitumor effects of tumor necrosis factor (TNF-α) were evaluated following transfection of TNF-α plasmid DNA into solid mouse tumors using the nanobubbles (NBs) and ultrasound (US) gene delivery system. Murine breast carcinoma (EMT6) cells expressing luciferase (1 × 10(6) cells) were injected intradermally into the flanks of 6-7-week-old male SCID mice on day 0. Ten microliters of TNF-α (5 μg/μL) or TNF-α mock plasmid DNA (5 μg/μL) with/without NBs (15 μL) and saline was injected intratumorally in a total volume of 30 μL, and tumors were exposed to US (frequency, 1 MHz; intensity, 3.0 W/cm(2); duty cycle, 20%; number of pulses, 200; and exposure time, 60 s) on days 2, 4, 7, and 9. Changes in tumor size were measured with an in vivo bioluminescent imaging system and a mechanical caliper. Changes in tumor vessel area were quantified using contrast-enhanced US imaging with Sonazoid and a high frequency US imaging system (40 MHz) and immunohistochemistry (CD31). At the mRNA level, expression of TNF-α, caspase-3, and p53 were quantified using real-time quantitative RT-PCR. At the protein level, expression of caspase-3 and p53 were confirmed by immunohistochemistry. We show that repeated TNF-α gene delivery using NBs and US can lead to the local production of TNF-α. This results in antitumor effects, including activation of p53-dependent apoptosis, decrease in tumor vessel density, and suppression of tumor size. In this study, we showed the effectiveness of using NBs and US for TNF-α gene delivery into tumor cells.

Pleiotropic functions of EAPII/TTRAP/TDP2: cancer development, chemoresistance and beyond

EAPII (also called TTRAP, TDP2), a protein identified a decade ago, has recently been shown to function as an oncogenic factor. This protein was also proven to be the first 5'- tyrosyl-DNA phosphodiesterase. EAPII has been demonstrated to have promiscuous protein associations, broad responsiveness to various extracellular signals, and pleiotropic functions in the development of human diseases including cancer and neurodegenerative disease. Emerging data suggest that EAPII is a multi-functional protein: EAPII repairs enzyme (topoisomerase)-mediated DNA damage by removing phosphotyrosine from DNA adducts; EAPII is involved in multiple signal transduction pathways such as TNF-TNFR, TGFβ and MAPK, and EAPII is responsive to immune defense, inflammatory response, virus infection and DNA toxins (chemo or radiation therapy). This review focuses on the current understanding of EAPII biology and its potential relations to many aspects of cancer development, including chromosome instability, tumorigenesis, tumor metastasis and chemoresistance, suggesting it as a potential target for intervention in cancer and other human diseases.

NSP 5a3a: a potential novel cancer target in head and neck carcinoma

NSP 5a3a along with three other distinct though similar splice variants were initially identified corresponding to locus HCMOGT-1 on chromosome 17p11.2 [1]. Secondary structure analysis of the novel structural protein (NSP) isoforms revealed similarity to Spectrin like proteins containing coiled coil domains [1]. The NSP 5a3a isoform had been found to be highly expressed in-vitro in particular cancer cell lines while very low to un-detectable levels in normal body tissues [1]. Subsequent investigation of this isoform revealed its novel interaction with B23 [2], a multifunctional nucleolar protein involved in ribosome biogenesis, rRNA transcription, mitosis, cell growth control, and apoptosis [3]. Subsequent investigation, elucidated NSP 5a3a's potential involvement in cellular processes such as ribosome biogenesis and rRNA processing by validating NSP 5a3a's novel interaction with B23 and ribonuclear protein hnRNP-L possibly implicating NSP 5a3a's involvement in cellular activities such as RNA metabolism and processing [4]. In this preliminary investigation, we wanted to observe the effect that over-expressing NSP 5a3a may have on cell cycle and its potential application in cancer treatment in aggressive cancers such as head and neck carcinomas. Over-expressed NSP 5a3a in HN30 cells induced a significant degree of apoptosis, an average of a 10.85 fold increase compared to controls 3 days post-transfection. This effect was more significant then the apoptosis observed between Fadu cells over-expressing NSP 5a3a and its controls. Though, the apoptosis induced in the WI38 control cell line showed an average of a 13.2 fold increase between treated and controls comparable to the HN30 cell line 3 days post-transfection. Molecular analysis indentified a novel p73 dependent mechanism independent of p53 and caspase 3 activity through which NSP 5a3a is inducing apoptosis. We propose NSP 5a3a as a potential therapeutic target for site directed cancer treatment in perhaps certain head and neck carcinomas by induction of apoptosis.

Thymidine phosphorylase in cancer cells stimulates human endothelial cell migration and invasion by the secretion of angiogenic factors

BACKGROUND

Thymidine phosphorylase (TP) is often overexpressed in tumours and has a role in tumour aggressiveness and angiogenesis. Here, we determined whether TP increased tumour invasion and whether TP-expressing cancer cells stimulated angiogenesis.

METHODS

Angiogenesis was studied by exposing endothelial cells (HUVECs) to conditioned medium (CM) derived from cancer cells with high (Colo320TP1=CT-CM, RT112/TP=RT-CM) and no TP expression after which migration (wound-healing-assay) and invasion (transwell-assay) were determined. The involvement of several angiogenic factors were examined by RT-PCR, ELISA and blocking antibodies.

RESULTS

Tumour invasion was not dependent on intrinsic TP expression. The CT-CM and RT-CM stimulated HUVEC-migration and invasion by about 15 and 40%, respectively. Inhibition by 10 μM TPI and 100 μM L-dR, blocked migration and reduced the invasion by 50-70%. Thymidine phosphorylase activity in HUVECs was increased by CT-CM. Reverse transcription-polymerase chain reaction revealed a higher mRNA expression of bFGF (Colo320TP1), IL-8 (RT112/TP) and TNF-α, but not VEGF. Blocking antibodies targeting these factors decreased the migration and invasion that was induced by the CT-CM and RT-CM, except for IL-8 in CT-CM and bFGF in RT-CM.

CONCLUSION

In our cell line panels, TP did not increase the tumour invasion, but stimulated the migration and invasion of HUVECs by two different mechanisms. Hence, TP targeting seems to provide a potential additional strategy in the field of anti-angiogenic therapy.

Catalase suppression-mediated H(2)O(2) accumulation in cancer cells by wogonin effectively blocks tumor necrosis factor-induced NF-κB activation and sensitizes apoptosis

Tremendous effort has been made to improve the anticancer value of tumor necrosis factor (TNF). In this study, we show that wogonin, a flavonoid isolated from Huang-Qin (Scutellaria baicalensis), synergistically sensitizes cancer cells derived from the cervix, ovary and lung to TNF-induced apoptosis, which was associated with inhibition of catalase activity and an increase of cellular hydrogen peroxide (H(2)O(2)). Wogonin-induced reactive oxygen species block TNF-induced NF-κB activation through inhibiting phosphorylation on the NF-κB p65 subunit and consequently the DNA binding of NF-κB. In addition, wogonin suppressed the expression of the antiapoptotic factor c-FLIP, which is accompanied with potentiation of TNF-induced caspase 8 activation that initiates apoptosis. Importantly, wogonin did not sensitize normal bronchial epithelial cells to TNF-induced cell death, which was associated with the defect in induction of H(2)O(2). Thus, wogonin specifically sensitizes cancer cells to TNF-induced cytotoxicity through H(2)O(2)-mediated NF-κB suppression and apoptosis activation. Our data provide important insights into the molecular mechanism underlying wogonin's anticancer activity, and suggest this common flavonoid could be used as a TNF adjuvant for cancer therapy.

A novel role for TNFAIP2: its correlation with invasion and metastasis in nasopharyngeal carcinoma

Tumor necrosis factor alpha (TNFα) is an inflammatory cytokine that is present in the microenvironment of many tumors and is known to promote tumor progression. To examine how TNFα modulates the progression and metastasis of nasopharyngeal carcinoma, we used Affymetrix chips to identify TNFα-inducible genes that are dysregulated in this tumor. Elevated expression of TNFAIP2, which encodes TNFα-inducible protein 2 and not previously known to be associated with cancer, was found and confirmed by quantitative RT-PCR of TNFAIP2 expression in nasopharyngeal carcinoma and adjacent normal tissues. Immunohistochemical analysis showed that the TNFAIP2 protein was highly expressed in tumor cells. Analysis of 95 nasopharyngeal carcinoma biopsy specimens revealed that high TNFAIP2 expression was significantly correlated with high-level intratumoral microvessel density (P=0.005) and low distant metastasis-free survival (P=0.001). A multivariate analysis further confirmed that TNFAIP2 was an independent prognostic factor for nasopharyngeal carcinoma (P=0.002). In vitro, TNFα treatment of nasopharyngeal carcinoma HK1 cells was found to induce TNFAIP2 expression, and siRNA-based knockdown of TNFAIP2 dramatically reduced the migration and invasion of nasopharyngeal carcinoma HK1 cells. These results collectively suggest for the first time that TNFAIP2 is a cell migration-promoting protein and its expression predicts distant metastasis. Our data suggest that TNFAIP2 may serve as an independent prognostic indicator for nasopharyngeal carcinoma.

NF-kappaB in lung cancer, a carcinogenesis mediator and a prevention and therapy target

Lung cancer ranks as the first malignant tumor killer worldwide. Despite the knowledge that carcinogens from tobacco smoke and the environment constitute the main causes of lung cancer, the mechanisms for lung carcinogenesis are still elusive. Cancer development and progression depend on the balance between cell survival and death signals. Common cell survival signaling pathways are activated by carcinogens as well as by inflammatory cytokines, which contribute substantially to cancer development. As a major cell survival signal, nuclear factor-kappaB (NF-kappaB) is involved in multiple steps in carcinogenesis and in cancer cell's resistance to chemo- and radio-therapy. Recent studies with animal models and cell culture systems have established the links between NF-kappaB and lung carcinogenesis, highlighting the significance of targeting NF-kappa signaling pathway for lung cancer treatment and chemoprevention. In this review, we summarize progresses in understanding the NF-kappaB pathway in lung cancer development as well as in modulating NF-kappaB for lung cancer prevention and therapy.

NSP 5a3a: a potential novel cancer target in head and neck carcinoma

NSP 5a3a along with three other distinct though similar splice variants were initially identified corresponding to locus HCMOGT-1 on chromosome 17p11.2 [1]. Secondary structure analysis of the novel structural protein (NSP) isoforms revealed similarity to Spectrin like proteins containing coiled coil domains [1]. The NSP 5a3a isoform had been found to be highly expressed in-vitro in particular cancer cell lines while very low to un-detectable levels in normal body tissues [1]. Subsequent investigation of this isoform revealed its novel interaction with B23 [2], a multifunctional nucleolar protein involved in ribosome biogenesis, rRNA transcription, mitosis, cell growth control, and apoptosis [3]. Subsequent investigation, elucidated NSP 5a3a's potential involvement in cellular processes such as ribosome biogenesis and rRNA processing by validating NSP 5a3a's novel interaction with B23 and ribonuclear protein hnRNP-L possibly implicating NSP 5a3a's involvement in cellular activities such as RNA metabolism and processing [4]. In this preliminary investigation, we wanted to observe the effect that over-expressing NSP 5a3a may have on cell cycle and its potential application in cancer treatment in aggressive cancers such as head and neck carcinomas. Over-expressed NSP 5a3a in HN30 cells induced a significant degree of apoptosis, an average of a 10.85 fold increase compared to controls 3 days post-transfection. This effect was more significant then the apoptosis observed between Fadu cells over-expressing NSP 5a3a and its controls. Though, the apoptosis induced in the WI38 control cell line showed an average of a 13.2 fold increase between treated and controls comparable to the HN30 cell line 3 days post-transfection. Molecular analysis indentified a novel p73 dependent mechanism independent of p53 and caspase 3 activity through which NSP 5a3a is inducing apoptosis. We propose NSP 5a3a as a potential therapeutic target for site directed cancer treatment in perhaps certain head and neck carcinomas by induction of apoptosis.

The induction of tumor necrosis factor-alpha, superoxide anion, myeloperoxidase, and superoxide dismutase in the peritoneal lavage cells of mice after prolonged exposure to dichloroacetate and trichloroacetate

The induction of phagocytic activation in response to prolonged treatment with different doses of dichloroacetate (DCA) and trichloroacetate (TCA) has been investigated in mice. Groups of B6C3F1 male mice were administered 7.7, 77, 154, and 410 mg of DCA or TCA/kg/day, postorally, for 4- and 13-weeks. Peritoneal lavage cells (PLCs) were isolated and assayed for the different biomarkers of phagocytic activation, including superoxide anion (SA), tumor necrosis factor-alpha (TNF-alpha), and myeloperoxidase (MPO). In addition, the role of superoxide dismutase (SOD) in the SA production was also assessed. DCA and TCA produced significant and dose-dependent increases in SA and TNF-alpha production and in MPO activity, but the increases in response to the high doses of the compounds (>77 mg/kg/day) in the 13-week treatment period were less significant than those produced in the 4-week treatment period. Also, dose-dependent increases in SOD activity were observed in both periods of treatments. In general, the results demonstrate significant induction of the biomarkers of phagocytic activation by doses of DCA and TCA that were previously shown to be noncarcinogenic, with significantly greater increases observed at the earlier period of exposure, as compared with later period. These findings may argue against the contribution of those mechanisms to the hepatotoxicity/hepatocarcinogenicity of the compounds and suggest them to be early adaptive/ protective mechanisms against their long-term effects.

Attenuating Smac mimetic compound 3-induced NF-kappaB activation by luteolin leads to synergistic cytotoxicity in cancer cells

Smac mimetics are potential anticancer therapeutics selectively killing cancer cells through autocrine tumor necrosis factor (TNF)-mediated apoptosis pathway. Our recent study reveal that the Smac mimetic compound 3 (SMC3)-activated NF-kappaB protects cancer cells against apoptosis, thus blunting SMC3's anticancer activity. Based on our previous observations that the nutrient flavonoid luteolin potently blocks TNF-induced NF-kappaB activation in cancer cells, we investigated if the combination of SMC3 and luteolin would achieve a synergistic anticancer activity. The results show that luteolin had no effect on autocrine TNF but it effectively blocked SMC3-induced nuclear factor kappa B (NF-kappaB) activation and expression of anti-apoptotic NF-kappaB targets. When SMC3 and luteolin were combined in treating cancer cells derived from lung and liver tumors, the activation of TNF-dependent apoptosis was markedly sensitized and a synergistic cytotoxic effect was achieved. In addition, the SMC3 and luteolin co-treatment had marginal effect on immortalized normal human bronchial epithelial cells. The results suggest that combination of SMC3 and luteolin is an effective approach for improving the anticancer value of SMC3, which has implications in cancer prevention and therapy.

Evoked pain behavior and spinal glia activation is dependent on tumor necrosis factor receptor 1 and 2 in a mouse model of bone cancer pain

Bone-cancer-related pain is one of the most disabling factors in patients suffering from primary bone cancer or bone metastases. Recent studies point toward an important role of proinflammatory cytokines, example tumor necrosis factor-alpha (TNF), for tumor growth and bone-cancer-associated pain. Mechanisms by which TNF, through its receptor subtypes, TNF receptor 1 (TNFR1) and -2 (TNFR2), elicits altered sensation and pain behavior, are still incompletely understood. To look for a potential role of TNF in bone cancer pain, cancer-related pain was analyzed in fibrosarcoma-bearing C57Bl/6J wild type mice after systemic antagonism of TNF. To further clarify the role of TNF receptor (TNFR) in bone-cancer pain, naive and fibrosarcoma-bearing C57Bl/ 6J wild type and transgenic mice with a deficiency of TNFR1 (TNFR1ko), TNFR2 (TNFR2ko), and TNFR1+2 (TNFR1+2ko) were compared regarding cancer-related pain and hyperalgesia, tumor growth, osteoclast activation, and spinal astrogliosis. Systemic antagonism of TNF significantly alleviated tactile hypersensitivity and spontaneous bone-cancer-related pain behavior. Most interestingly, combined deletion of the TNFR1 and TNFR2, but not of either gene alone, almost completely inhibited the development of tactile hypersensitivity, whereas spontaneous pain behavior was transiently increased. Accordingly, spinal astrogliosis was markedly reduced, whereas tumor growth was significantly increased in TNFR1+2ko mice. In contrast, deletion of the TNFR1 or TNFR2 gene alone did not change tumor growth or spinal astrogliosis. Our findings suggest that the combined absence of TNFR1 and TNFR2 is necessary for the attenuation of cancer-related tactile hypersensitivity and concomitant spinal astrogliosis, whereas tumor growth seems to be inhibited by combined TNFR activation. These findings support the hypothesis of cytokine-dependent pain development in cancer pain. Differential targeting of TNFR activation could be an interesting strategy in bone-cancer-related pain conditions.

Acquired activation of the Akt/cyclooxygenase-2/Mcl-1 pathway renders lung cancer cells resistant to apoptosis

Acquired apoptosis resistance plays an important role in acquired chemoresistance in cancer cells during chemotherapy. Our previous observations demonstrated that acquired tumor necrosis factor-related apoptosis-inducing ligand resistance in lung cancer cells was associated with Akt-mediated stabilization of cellular FLICE-like inhibitory protein (c-FLIP) and Mcl-1. In this report, we determined that these cells also have acquired resistance to apoptosis induced by chemotherapeutics such as cisplatin and doxorubicin (Adriamycin), which was detected in vitro in cell cultures and in vivo in xenografted tumors. We further found that cyclooxygenase-2 (COX-2) is dramatically overexpressed in cells with acquired apoptosis resistance. COX-2 seems to be a crucial mediator in acquired apoptosis resistance because suppressing COX-2 activity with a chemical inhibitor or reducing COX-2 protein expression level with COX-2 small interfering RNA dramatically alleviated resistance to therapeutic-induced apoptosis. Inhibiting Akt markedly suppressed COX-2 expression, suggesting COX-2 is a downstream effector of this cell survival kinase-mediated apoptosis resistance. Furthermore, the expression of Mcl-1 but not c-FLIP was significantly reduced when COX-2 was suppressed, and knockdown of Mcl-1 substantially sensitized the cells to apoptosis. Our results establish a novel pathway that consists of Akt, COX-2, and Mcl-1 for acquired apoptosis resistance, which could be a molecular target for circumventing acquired chemoresistance in lung cancer.

Tumor necrosis factor alpha induces p53 up-regulated modulator of apoptosis expression in colorectal cancer cell lines

PURPOSE

Inflammatory bowel disease (IBD)-associated colorectal carcinogenesis involves dysregulation of multiple cellular pathways, including p53 signaling and cytokine action. The purpose of the current study was to evaluate the effects of tumor necrosis factor alpha (TNF-alpha) on p53 and p53 up-regulated modulator of apoptosis (PUMA), a downstream effector of p53 in the apoptotic pathway in colorectal cancer cells.

METHODS

The cell lines HT29 (which express mutant p53) and HCT116 (which express wild-type p53) were treated with TNF-alpha (0, 50, 100, or 500 ng/mL) for 1, 12, 24, or 48 hours. Protein expression and subcellular localization of p53 and PUMA were determined by immunoblot and immunofluorescence. Changes in p53 and PUMA mRNA expression were determined by quantitative real time polymerase chain reaction.

RESULTS

Nuclear p53 expression was increased in TNF-alpha-treated HT29 cells; in contrast, expression was decreased or minimally changed in TNF-alpha-treated HCT116 cells, as determined by immunoblot and immunofluorescence. At 24 hours, p53 mRNA transcript levels were minimally increased in HT29 cells, whereas PUMA increased 34-fold.

CONCLUSIONS

TNF-alpha increased nuclear p53 expression in HT29 cells, which express p53 mutation, but not in HCT116 cells, which are wild type for p53. In addition, TNF-alpha markedly up-regulated PUMA mRNA levels in HT29 cells. Our findings suggest that TNF-alpha may be a factor in carcinogenesis in IBD in cells carrying a p53 mutation.

The NF-kappaB activation pathways, emerging molecular targets for cancer prevention and therapy

IMPORTANCE OF THE FIELD

Nuclear factor kappa B (NF-kappaB) is activated by a variety of cancer-promoting agents. The reciprocal activation between NF-kappaB and inflammatory cytokines makes NF-kappaB important for inflammation-associated cancer development. Both the constitutive and anticancer therapeutic-induced NF-kappaB activation blunts the anticancer activities of the therapy. Elucidating the roles of NF-kappaB in cancer facilitates developing approaches for cancer prevention and therapy.

AREAS COVERED IN THIS REVIEW

By searching PubMed, we summarize the progress of studies on NF-kappaB in carcinogenesis and cancer cells' drug resistance in recent 10 years.

WHAT THE READER WILL GAIN

The mechanisms by which NF-kappaB activation pathways are activated; the roles and mechanisms of NF-kappaB in cell survival and proliferation, and in carcinogenesis and cancer cells' response to therapy; recent development of NF-kappaB-modulating means and their application in cancer prevention and therapy.

TAKE HOME MESSAGE

NF-kappaB is involved in cancer development, modulating NF-kappaB activation pathways has important implications in cancer prevention and therapy. Due to the complexity of NF-kappaB roles in different cancers, careful evaluation of NF-kappaB's in each cancer type is crucial in this regard. More cancer cell-specific NF-kappaB inhibiting means are desired for improving anticancer efficacy and reducing systemic toxicity.

Angiogenesis in cutaneous disease: part I

Angiogenesis is an important process in normal physiology and disease pathogenesis. Angiogenesis is controlled in a healthy body by a system of angiogenic growth factors and angiogenesis inhibitors. When angiogenic growth factors are predominantly expressed, blood vessel growth occurs and disease may result. Successful therapies have been developed that target growth factors, their receptors, or the cascade pathways that are activated by growth factor/receptor interactions. There is good evidence that angiogenesis plays an important role in a wide range of cutaneous maladies, and angiogenesis-targeting therapies are playing an increasing role in the management of dermatologic disease. Cutaneous angiogenesis offers an exciting new arena for targeted dermatologic therapeutics.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to distinguish angiogenic growth factors and inhibitors, recognize angiogenic mediating agents and compare their mechanisms of action, and apply the use of angiogenic mediating agents in clinical and research situations.

IKKbeta-mediated nuclear factor-kappaB activation attenuates smac mimetic-induced apoptosis in cancer cells

Smac mimetics (SM) have been recently reported to kill cancer cells through the extrinsic apoptosis pathway mediated by autocrine tumor necrosis factor (TNF). SM also activates nuclear factor-kappaB (NF-kappaB). However, how SM induces NF-kappaB and the role of NF-kappaB in SM-induced cancer cell death has not been well elucidated. We found that effective blockage of NF-kappaB had no detectable effect on SM compound 3 (SMC3)-induced TNF secretion, suggesting that the induction of TNF by SMC3 is independent of NF-kappaB. Conversely, SMC3-induced NF-kappaB activation was found to be mediated by autocrine TNF because this effect of SMC3 was effectively inhibited when TNF was blocked with either a TNF neutralizing antibody or TNF small interfering RNA. In addition, although SMC3 dramatically reduced c-IAP1 level, it had marginal effect on c-IAP2 expression, TNF-induced RIP modification, NF-kappaB activation, and downstream antiapoptosis NF-kappaB target expression. Furthermore, blocking NF-kappaB by targeting IKKbeta or RelA substantially potentiated SMC3-induced cytotoxicity, suggesting that the NF-kappaB pathway inhibits SMC3-induced apoptosis in cancer cells. Our results show that through TNF autocrine, SM induces an IKKbeta-mediated NF-kappaB activation pathway that protects cancer cells against SM-induced apoptosis, and thus, NF-kappaB blockage could be an effective approach for improving the anticancer value of SM.