Nuclear factor-κB as a predictor of treatment response in breast cancer

Cell plasticity modulation by flavonoids in resistant breast carcinoma targeting the nuclear factor kappa B signaling

Cancer cell plasticity plays a crucial role in tumor initiation, progression, and metastasis and is implicated in the multiple cancer defense mechanisms associated with therapy resistance and therapy evasion. Cancer resistance represents one of the significant obstacles in the clinical management of cancer. Some reversal chemosensitizing agents have been developed to resolve this serious clinical problem, but they have not yet been proven applicable in oncological practice. Activated nuclear factor kappa B (NF-κB) is a frequently observed biomarker in chemoresistant breast cancer (BC). Therefore, it denotes an attractive cellular target to mitigate cancer resistance. We summarize that flavonoids represent an essential class of phytochemicals that act as significant regulators of NF-κB signaling and negatively affect the fundamental cellular processes contributing to acquired cell plasticity and drug resistance. In this regard, flavokawain A, icariin, alpinetin, genistein, wogonin, apigenin, oroxylin A, xanthohumol, EGCG, hesperidin, naringenin, orientin, luteolin, delphinidin, fisetin, norwogonin, curcumin, cardamonin, methyl gallate and catechin-3-O-gallate, ampelopsin, puerarin, hyperoside, baicalein, paratocarpin E, and kaempferol and also synthetic flavonoids such as LFG-500 and 5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone have been reported to specifically interfere with the NF-κB pathway with complex signaling consequences in BC cells and could be potentially crucial in re-sensitizing unresponsive BC cases. The targeting NF-κB by above-mentioned flavonoids includes the modification of tumor microenvironment and epithelial-mesenchymal transition, growth factor receptor regulations, and modulations of specific pathways such as PI3K/AKT, MAP kinase/ERK, and Janus kinase/signal transduction in BC cells. Besides that, NF-κB signaling in BC cells modulated by flavonoids has also involved the regulation of ATP-binding cassette transporters, apoptosis, autophagy, cell cycle, and changes in the activity of cancer stem cells, oncogenes, or controlling of gene repair. The evaluation of conventional therapies in combination with plasticity-regulating/sensitizing agents offers new opportunities to make significant progress towards a complete cure for cancer.

Molecular mechanisms of resveratrol as chemo and radiosensitizer in cancer

One of the primary diseases that cause death worldwide is cancer. Cancer cells can be intrinsically resistant or acquire resistance to therapies and drugs used for cancer treatment through multiple mechanisms of action that favor cell survival and proliferation, becoming one of the leading causes of treatment failure against cancer. A promising strategy to overcome chemoresistance and radioresistance is the co-administration of anticancer agents and natural compounds with anticancer properties, such as the polyphenolic compound resveratrol (RSV). RSV has been reported to be able to sensitize cancer cells to chemotherapeutic agents and radiotherapy, promoting cancer cell death. This review describes the reported molecular mechanisms by which RSV sensitizes tumor cells to radiotherapy and chemotherapy treatment.

Inhibition of NF-кB Expression in LPS-Induced RAW264.7 Macrophage Cells by a Thiazolidinone Derivative (TZDOCH2CH3)

To date, various derivatives of thiazolidinone in a variety of cell lines have been investigated. The present study aimed to evaluate the toxicity and inhibitory effects of a thiazolidinone derivative called 5-(2,4-bis-4-ethoxy-phenyl azo)-3-hydroxy-benzylidine)-2,4-thiazolidinone (TZD-OCH2CH3) on the expression of NF-кB in LPS-induced RAW264.7 macrophage cell lines. Different concentrations of the MTT assay(0-120 μg/mL) were performed to estimate the biological rate of the cells. The half-maximal inhibitory concentration (IC50) of TZD-OCH2CH3-treated RAW264.7 cells was found to be 115 μg/mL. To determine the inhibitory effect of the synthesized compound on the expression changes of NF-кB, the RAW264.7cells were initially induced with LPS and then treated by 15, 30 and 60 μg/mL of TZD-OCH2CH3. Realtime PCR results confirmed a strong inhibitory effect of TZD-OCH2CH3 on the expression of NF-кB inLPS-induced RAW264.7 cells (IC50 = 48 μg/mL). Overall, these findings suggested that the derivative TZDOCH2CH3 had a significant anti-inflammatory effect.

Resveratrol and Resveratrol-Aspirin Hybrid Compounds as Potent Intestinal Anti-Inflammatory and Anti-Tumor Drugs

Resveratrol (3,4,5-Trihydroxy-trans-stilbene) is a naturally occurring polyphenol that exhibits beneficial pleiotropic health effects. It is one of the most promising natural molecules in the prevention and treatment of chronic diseases and autoimmune disorders. One of the key limitations in the clinical use of resveratrol is its extensive metabolic processing to its glucuronides and sulfates. It has been estimated that around 75% of this polyphenol is excreted via feces and urine. To possibly alleviate the extensive metabolic processing and improve bioavailability, we have added segments of acetylsalicylic acid to resveratrol in an attempt to maintain the functional properties of both. We initially characterized resveratrol-aspirin derivatives as products that can inhibit cytochrome P450 Family 1 Subfamily A Member 1 (CYP1A1) activity, DNA methyltransferase (DNMT) activity, and cyclooxygenase (COX) activity. In this study, we provide a detailed analysis of how resveratrol and its aspirin derivatives can inhibit nuclear factor kappa B (NFκB) activation, cytokine production, the growth rate of cancer cells, and in vivo alleviate intestinal inflammation and tumor growth. We identified resveratrol derivatives C3 and C11 as closely preserving resveratrol bioactivities of growth inhibition of cancer cells, inhibition of NFκB activation, activation of sirtuin, and 5’ adenosine monophosphate-activated protein kinase (AMPK) activity. We speculate that the aspirin derivatives of resveratrol would be more metabolically stable, resulting in increased efficacy for treating immune disorders and as an anti-cancer agent.

Tumor Necrosis Factor α Blockade: An Opportunity to Tackle Breast Cancer

Breast cancer is the most frequently diagnosed cancer and the principal cause of mortality by malignancy in women and represents a main problem for public health worldwide. Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine whose expression is increased in a variety of cancers. In particular, in breast cancer it correlates with augmented tumor cell proliferation, higher malignancy grade, increased occurrence of metastasis and general poor prognosis for the patient. These characteristics highlight TNFα as an attractive therapeutic target, and consequently, the study of soluble and transmembrane TNFα effects and its receptors in breast cancer is an area of active research. In this review we summarize the recent findings on TNFα participation in luminal, HER2-positive and triple negative breast cancer progression and metastasis. Also, we describe TNFα role in immune response against tumors and in chemotherapy, hormone therapy, HER2-targeted therapy and anti-immune checkpoint therapy resistance in breast cancer. Furthermore, we discuss the use of TNFα blocking strategies as potential therapies and their clinical relevance for breast cancer. These TNFα blocking agents have long been used in the clinical setting to treat inflammatory and autoimmune diseases. TNFα blockade can be achieved by monoclonal antibodies (such as infliximab, adalimumab, etc.), fusion proteins (etanercept) and dominant negative proteins (INB03). Here we address the different effects of each compound and also analyze the use of potential biomarkers in the selection of patients who would benefit from a combination of TNFα blocking agents with HER2-targeted treatments to prevent or overcome therapy resistance in breast cancer.

Combination of Ruthenium Complex and Doxorubicin Synergistically Inhibits Cancer Cell Growth by Down-Regulating PI3K/AKT Signaling Pathway

Combinational use of drugs has been a common strategy in cancer treatment because of synergistic advantages in reducing dose and toxicity, minimizing or delaying drug resistance. To improve the efficacy of chemotherapy, various potential combinations have been investigated. Ruthenium complex is considered a potential alternative of the platinum-based drugs due to its significant efficacy and safety. Previously, we reported that ruthenium(II) complex (Δ-Ru1) has great anticancer potential and minor toxicity toward normal tissues. However, the therapeutic efficacy and mechanism of action of ruthenium(II) complex combined with other anticancer drugs is still unknown. Here, we investigated the combinational effect of Δ-Ru1 and doxorubicin in different cancer cells. The data assessed by Chou-Talalay method showed significant synergism in MCF-7 cells. Furthermore, the results in antiproliferation efficacy indicated that the combination showed strong cytotoxicity and increasing apoptosis of MCF-7 cells in 2D and 3D multicellular tumor spheroids (MCTSs). Significant inhibition of MCF-7 cells accompanied with increased ROS generation was observed. Furthermore, the expression of PI3K/AKT was significantly down-regulated, while the expression of PTEN was strongly up-regulated in cells treated with combination of Δ-Ru1 and doxorubicin. The expression of NF-κB and XIAP decreased while the expression of P53 increased and associated with apoptosis. These findings suggest that the combination of ruthenium complex and doxorubicin has a significant synergistic effect by down-regulating the PI3K/AKT signaling pathway in MCF-7 cells. This study may trigger more research in ruthenium complex and combination therapy that will be able to provide opportunities for developing better therapeutics for cancer treatment.

DNLC: differential network local consistency analysis

BACKGROUND

The biological network is highly dynamic. Functional relations between genes can be activated or deactivated depending on the biological conditions. On the genome-scale network, subnetworks that gain or lose local expression consistency may shed light on the regulatory mechanisms related to the changing biological conditions, such as disease status or tissue developmental stages.

RESULTS

In this study, we develop a new method to select genes and modules on the existing biological network, in which local expression consistency changes significantly between clinical conditions. The method is called DNLC: Differential Network Local Consistency. In simulations, our algorithm detected artificially created local consistency changes effectively. We applied the method on two publicly available datasets, and the method detected novel genes and network modules that were biologically plausible.

CONCLUSIONS

The new method is effective in finding modules in which the gene expression consistency change between clinical conditions. It is a useful tool that complements traditional differential expression analyses to make discoveries from gene expression data. The R package is available at https://cran.r-project.org/web/packages/DNLC.

Mechanisms of apoptosis modulation by curcumin: Implications for cancer therapy

Cancer incidences are growing and cause millions of deaths worldwide. Cancer therapy is one of the most important challenges in medicine. Improving therapeutic outcomes from cancer therapy is necessary for increasing patients' survival and quality of life. Adjuvant therapy using various types of antibodies or immunomodulatory agents has suggested modulating tumor response. Resistance to apoptosis is the main reason for radioresistance and chemoresistance of most of the cancers, and also one of the pivotal targets for improving cancer therapy is the modulation of apoptosis signaling pathways. Apoptosis can be induced by intrinsic or extrinsic pathways via stimulation of several targets, such as membrane receptors of tumor necrosis factor-α and transforming growth factor-β, and also mitochondria. Curcumin is a naturally derived agent that induces apoptosis in a variety of different tumor cell lines. Curcumin also activates redox reactions within cells inducing reactive oxygen species (ROS) production that leads to the upregulation of apoptosis receptors on the tumor cell membrane. Curcumin can also upregulate the expression and activity of p53 that inhibits tumor cell proliferation and increases apoptosis. Furthermore, curcumin has a potent inhibitory effect on the activity of NF-κB and COX-2, which are involved in the overexpression of antiapoptosis genes such as Bcl-2. It can also attenuate the regulation of antiapoptosis PI3K signaling and increase the expression of MAPKs to induce endogenous production of ROS. In this paper, we aimed to review the molecular mechanisms of curcumin-induced apoptosis in cancer cells. This action of curcumin could be applicable for use as an adjuvant in combination with other modalities of cancer therapy including radiotherapy and chemotherapy.

Mechanisms of nonsteroidal anti-inflammatory drugs in cancer prevention

Various clinical and epidemiologic studies show that nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin and cyclooxygenase inhibitors (COXIBs) help prevent cancer. Since eicosanoid metabolism is the main inhibitory targets of these drugs the resulting molecular and biological impact is generally accepted. As our knowledge base and technology progress we are learning that additional targets may be involved. This review attempts to summarize these new developments in the field.

Curcumin reduces cytotoxicity of 5-Fluorouracil treatment in human breast cancer cells

Antimetabolites have proven successful as therapeutics for advanced-stage breast cancers, but are often accompanied by severe side effects that can limit treatment regimens. 5-Fluorouracil (5-FU), an antimetabolite that inhibits cell proliferation, has served an important role in standard chemotherapy protocols for a variety of solid tumors. Although reasonable response rates have been reported for 5-FU, continued exploration is necessary to improve clinical outcomes and reduce cytotoxic side effects that are an inherent problem for chemotherapeutic interventions. Because of its diverse anticancer properties, we explored whether by combining the natural product curcumin with 5-FU, synergistic improvements in preventing breast cancer cell proliferation and/or provide protection against 5-FU-induced cytotoxicity could be achieved. Indeed both curcumin and 5-FU inhibit DNA synthesis in MDA-MB-231 cells using BrdU incorporation assays; however, combined treatment showed no synergistic improvement. We next established the cytotoxicity profile for 5-FU in MDA-MB-231 cells using a tetrazolium-based cell viability assay and obtained an LD50 value of 28 μM. When 5-FU incubations were repeated with the addition of curcumin, the LD50 value increased to 200-300 μM, representing a 7-10-fold protection by curcumin against 5-FU cytotoxicity. These findings suggest that the addition of curcumin as an adjuvant therapy during 5-FU treatment might enhance the chemotherapeutic effectiveness of 5-FU by protecting normal cells from reduced viability and thus permitting higher dosing or longer treatment times. This would be especially important to those individuals who are plagued with severe cytotoxicities and require frequent interruptions, or even early termination of their treatment regimens.

IKKβ inhibitor in combination with bortezomib induces cytotoxicity in breast cancer cells

Bortezomib is a proteasome inhibitor with remarkable clinical antitumor activity in multiple myeloma (MM) and is under evaluation in clinical trials in various types of cancer including breast cancer. Although the initial rationale for its use in cancer treatment was the inhibition of NF-κB activity by blocking proteasomal degradation of IκBα, direct evidence indicating inhibition of constitutive NF-κB activity by bortezomib in tumor cells in patients has not yet been reported. Moreover, recent studies have shown that bortezomib activates constitutive NF-κB activity via stimulating the canonical pathway in MM cells. In this study, we first examined protein expression of IκBα after bortezomib treatment. We observed that bortezomib upregulated the phosphorylation and downregulated IκBα protein expression in a dose- and time-dependent manner in MCF7 and T47D cells, associated with phosphorylation of IKKβ. Since IκBα is an inhibitor of nuclear translocation of NF-κB, we further examined alteration of NF-κB activity by bortezomib. Importantly, bortezomib significantly upregulates NF-κB activity in both MCF7 and T47D in a dose-dependent fashion, demonstrated by electrophoretic mobility shift analysis (EMSA). Furthermore, immunocytochemical analysis confirmed enhanced nuclear translocation of p65 NF-κB (RelA) by bortezomib treatment. Supershift assay showed supershifted bands by anti-p65 and -p50 antibodies. Taken together, these results indicate that bortezomib activates the canonical NF-κB pathway in both cell lines. Finally, we demonstrated that IKKβ inhibitor enhanced cytotoxicity, associated with inhibition of NF-κB activity induced by bortezomib in MCF7 and T47D breast cancer cells.

Phytochemicals as chemosensitizers: from molecular mechanism to clinical significance

This review provides an overview of the clinical relevance of chemosensitization, giving special reference to the phenolic phytochemicals, curcumin, genistein, epigallocatechin gallate, quercetin, emodin, and resveratrol, which are potential candidates due to their ability to regulate multiple survival pathways without inducing toxicity. We also give a brief summary of all the clinical trials related to the important phytochemicals that emerge as chemosensitizers. The mode of action of these phytochemicals in regulating the key players of the death receptor pathway and multidrug resistance proteins is also abridged. Rigorous efforts in identifying novel chemosensitizers and unraveling their molecular mechanism have resulted in some of the promising candidates such as curcumin, genistein, and polyphenon E, which have gone into clinical trials. Even though considerable research has been conducted in identifying the salient molecular players either contributing to drug efflux or inhibiting DNA repair and apoptosis, both of which ultimately lead to the development of chemoresistance, the interdependence of the molecular pathways leading to chemoresistance is still the impeding factor in the success of chemotherapy. Even though clinical trials are going on to evaluate the chemosensitizing efficacy of phytochemicals such as curcumin, genistein, and polyphenon E, recent results indicate that more intense study is required to confirm their clinical efficacy. Current reports also warrant intense investigation about the use of more phytochemicals such as quercetin, emodin, and resveratrol as chemosensitizers, as all of them have been shown to modulate one or more of the key regulators of chemoresistance.

MicroRNA-31 sensitizes human breast cells to apoptosis by direct targeting of protein kinase C epsilon (PKCepsilon)

MicroRNAs post-transcriptionally regulate gene expression and thereby contribute to the modulation of numerous complex and disease-relevant cellular phenotypes, including cell proliferation, cell motility, apoptosis, and stress response. In breast cancer cell systems, miR-31 has been shown to inhibit cell migration, invasion, and metastasis. Here, we link enhanced expression of miR-31 to the inhibition of the oncogenic NF-κB pathway, thus supporting the tumor-suppressive function of this microRNA. We identified protein kinase C epsilon (PKCε encoded by the PRKCE gene) as a novel direct target of miR-31 and show that down-regulation of PKCε results in impaired NF-κB signaling, enhanced apoptosis, and increased sensitivity of MCF10A breast epithelial and MDA-MB-231 triple-negative breast cancer cells toward ionizing radiation as well as treatment with chemotherapeutics. Mechanistically, we attribute this sensitization to anti-cancer treatments to the PRKCE-mediated down-regulation of the anti-apoptotic factor BCL2. In clinical breast cancer samples, high BCL2 expression was associated with poor prognosis. Furthermore, we found an inverse correlation between miR-31 and BCL2 expression, highlighting the functional relevance of the indirect down-regulation of BCL2 via direct targeting of PRKCE by miR-31.

Modulation of apoptotic signaling by the hepatitis B virus X protein

Worldwide, an estimated 350 million people are chronically infected with the Hepatitis B Virus (HBV); chronic infection with HBV is associated with the development of severe liver diseases including hepatitis and cirrhosis. Individuals who are chronically infected with HBV also have a significantly higher risk of developing hepatocellular carcinoma (HCC) than uninfected individuals. The HBV X protein (HBx) is a key regulatory HBV protein that is important for HBV replication, and likely plays a cofactor role in the development of HCC in chronically HBV-infected individuals. Although some of the functions of HBx that may contribute to the development of HCC have been characterized, many HBx activities, and their putative roles during the development of HBV-associated HCC, remain incompletely understood. HBx is a multifunctional protein that localizes to the cytoplasm, nucleus, and mitochondria of HBV‑infected hepatocytes. HBx regulates numerous cellular signal transduction pathways and transcription factors as well as cell cycle progression and apoptosis. In this review, we will summarize reports in which the impact of HBx expression on cellular apoptotic pathways has been analyzed. Although various effects of HBx on apoptotic pathways have been observed in different model systems, studies of HBx activities in biologically relevant hepatocyte systems have begun to clarify apoptotic effects of HBx and suggest mechanisms that could link HBx modulation of apoptotic pathways to the development of HBV-associated HCC.

Mountain ginseng extract exhibits anti-lung cancer activity by inhibiting the nuclear translocation of NF-κB

Administration of mountain ginseng (MG) extract can restore advanced cancer to a normal state. To elucidate the mechanism by which MG extract prevents the progression of lung cancer, the processes of proliferation and death of lung cancer cells (A549) were examined after treatment with MG extract. Butanol-extracted MG (BX-MG) showed a high inhibitory effect (IC(50) = 2 mg/ml) by attenuating proliferation and inducing apoptosis in lung cancer cells. By HPLC-UV analysis of BX-MG, ginsenosides, Rb1 was identified as the most abundant ginsenoside, followed by Rg1, Re, Rc and Rb2. BX-MG induced caspase-3 dependent apoptosis by inhibiting NF-κB. In addition, BX-MG activated p53 and p21, resulting in the attenuated proliferation of A549 cells. Reduced activity of the NF-κB promoter and increased activity of the p53 promoter indicate that BX-MG regulates apoptosis at the level of transcription in lung cancer cells. Furthermore, BX-MG blocked the nuclear translocation of RelA and the associated reduction in surviving. These results suggest that BX-MG inhibits lung cancer cell growth by activating tumor suppressors and inhibiting nuclear translocation of NF-κB.

Water extract of Cynanchi atrati Radix regulates inflammation and apoptotic cell death through suppression of IKK-mediated NF-κB signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Cynanchi atrati Radix has been traditionally used as an anti-inflammatory agent to treat febrile diseases, acute urinary infection or subcutaneous pyogenic infection with invasion of the pathogenic factors.

AIM OF STUDY

Nuclear factor (NF)-κB is a pleiotropic transcriptional factor of many genes involved in inflammatory and anti-apoptotic responses. To identify a novel, potent inhibitor of NF-κB signaling pathway, a plant extract library of traditional oriental medicine was screened for the capability to block the NF-κB activity in cells overexpressing toll-like receptor 4 (TLR4), and then evaluated the anti-inflammatory and pro-apoptotic functions of water extract of Cynanchi atrati Radix (WECR) in macrophages and cancer cells, respectively.

MATERIALS AND METHODS

The effect of WECR on the proinflammatory mediators (inducible NO synthase [iNOS], cyclooxygenase [COX]-2), IκB-α degradation, RelA/p65 phosphorylation and caspase cleavages were measured by immunblotting. NF-κB transcriptional activity, IκB kinase (IKK) activity and nitric oxide (NO) production was measured using the luciferase assay, in vitro kinase assay and Griess reaction.

RESULTS

WECR efficiently inhibited LPS-induced expression of proinflammatory mediators including iNOS and COX-2. IKK kinase activity, IκB-α degradation, nuclear translocation of RelA/p65 and NF-κB transcriptional activity induced by LPS were suppressed by WECR. Furthermore, WECR dramatically enhances the apoptotic response, as evident by the combination with tumor necrosis factor (TNF) was able to induce the cytotoxic action through caspase-dependent pathway.

CONCLUSION

These results indicate that WECR has a potential to inhibit IKK-mediated NF-κB activation, and is a valuable compound for modulating inflammatory or cancerous conditions.

Inflammation and cancer: how friendly is the relationship for cancer patients?

Evidence has emerged in the last two decades that at the molecular level most chronic diseases, including cancer, are caused by a dysregulated inflammatory response. The identification of transcription factors such as NF-kappaB, AP-1 and STAT3 and their gene products such as tumor necrosis factor, interleukin-1, interleukin-6, chemokines, cyclooxygenase-2, 5 lipooxygenase, matrix metalloproteases, and vascular endothelial growth factor, adhesion molecules and others have provided the molecular basis for the role of inflammation in cancer. These inflammatory pathways are activated by tobacco, stress, dietary agents, obesity, alcohol, infectious agents, irradiation, and environmental stimuli, which together account for as much as 95% of all cancers. These pathways have been implicated in transformation, survival, proliferation, invasion, angiogenesis, metastasis, chemoresistance, and radioresistance of cancer, so much so that survival and proliferation of most types of cancer stem cells themselves appear to be dependent on the activation of these inflammatory pathways. Most of this evidence, however, is from preclinical studies. Whether these pathways have any role in prevention, progression, diagnosis, prognosis, recurrence or treatment of cancer in patients, is the topic of discussion of this review. We present evidence that inhibitors of inflammatory biomarkers may have a role in both prevention and treatment of cancer.

The potential for treatment with dietary long-chain polyunsaturated n-3 fatty acids during chemotherapy

Dietary intake of long-chain omega-3 (or n-3) polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) can affect numerous processes in the body, including cardiovascular, neurological and immune functions, as well as cancer. Studies on human cancer cell lines, animal models and preliminary trials with human subjects suggest that administration of EPA and DHA, found naturally in our diet in fatty fish, can alter toxicities and/or activity of many drugs used to treat cancer. Multiple mechanisms are proposed to explain how n-3 PUFA modulate the tumor cell response to chemotherapeutic drugs. n-3 PUFA are readily incorporated into cell membranes and lipid rafts, and their incorporation may affect membrane-associated signaling proteins such as Ras, Akt and Her-2/neu. Due to their high susceptibility to oxidation, it has also been proposed that n-3 PUFA may cause irreversible tumor cell damage through increased lipid peroxidation. n-3 PUFA may increase tumor cell susceptibility to apoptosis by altering expression or function of apoptotic proteins, or by modulating activity of survival-related transcription factors such as nuclear factor-kappaB. Some studies suggest n-3 PUFA may increase drug uptake or even enhance drug activation (e.g., in the case of some nucleoside analogue drugs). Further research is warranted to identify specific mechanisms by which n-3 PUFA increase chemotherapy efficacy and to determine the optimal cellular/membrane levels of n-3 PUFA required to promote these mechanisms, such that these fatty acids may be prescribed as adjuvants to chemotherapy.

Acquisition of stable inducible up-regulation of nuclear factor-kappaB by tumor necrosis factor exposure confers increased radiation resistance without increased transformation in breast cancer cells

High-grade breast cancers are better adapted to hypoxia and more resistant to chemotherapy and radiotherapy. Constitutive activation of the transcription factor nuclear factor-kappaB (NF-kappaB) increases in breast tumors and in breast cancer cell lines, where it promotes chemoradiation resistance, in part by activation of antiapoptotic genes. The role for up-regulation of NF-kappaB in breast cancer progression is less clear. Here, we first show that whereas the constitutive activity of NF-kappaB is incrementally elevated from immortalized breast epithelial to frank transformed invasive ductal breast cancer cell lines (~3-fold, +/-0.1-fold, P < 0.05), inflammatory cytokine-inducible activity is further increased (up to 9-fold, +/-0.9-fold, P < 0.05). We then show that inhibition of NF-kappaB activity selectively sensitizes transformed but not immortalized cells to killing by ionizing radiation or low levels of tumor necrosis factor (TNF) by up to 10-fold (+/-1-fold, P < 0.05) but has little effect on hypoxia-mediated cell death. Prolonged cultivation of immortalized and partially transformed cells in TNF selected for cells displaying stable constitutive and strongly inducible overexpression of NF-kappaB even in the absence of TNF. Stable acquisition of increased NF-kappaB activity conferred resistance to ionizing radiation or inflammatory cytokines, which was dependent on elevated NF-kappaB activity, but had no effect on transformation potential measured by in vitro and in vivo parameters. Thus, TNF and possibly other inflammatory cytokines in the tumor-stroma matrix likely select for breast cancer cells that stably overexpress NF-kappaB, leading to greater cancer cell survival. Greater cell survival despite increased genomic injury may permit increased acquisition of malignant genetic alterations as well as resistance to chemoradiation therapy.

Radiosensitization by diospyrin diethylether in MCF-7 breast carcinoma cell line

The development of radio-resistant tumor cells might be overcome by the use of tumor selective cytotoxic agents in combination with radiation treatment of cancer. Thus, we are exploring the radiomodifying potential of D7, a tumor-inhibitory compound derived from a plant product, diospyrin, in breast carcinoma cells, MCF-7. The present study indicated that D7 could enhance the radiation-induced cytotoxicity and apoptosis through down-regulation of the anti-apoptotic Bcl-2 and COX-2 gene expression, and up-regulation of pro-apoptotic genes, like p53 and p21. The higher expression of PUMA, a pro-apoptotic protein was also observed in the combination treatment. Effect of D7 on up-regulation of p21 expression in irradiated MCF-7 cells was concomitant with the cell cycle arrest in the G1 phase. Thus, it was concluded that D7 could sensitize the effect of radiation in breast carcinoma by regulating the gene expression involved in cell cycle and apoptosis.

Nuclear factor-kappaB (NF-kappaB) is frequently expressed in lung cancer and preneoplastic lesions

BACKGROUND

Nuclear factor-kappaB (NF-kappaB), a key transcription factor thought to play a major role in carcinogenesis, regulates many important signaling pathways involved in tumor promotion. Although NF-kappaB can be activated in lung cancer cell lines by tobacco exposure, there have been no studies of the expression of NF-kappaB in lung cancer pathogenesis.

METHODS

The immunohistochemical expression of NF-kappaB p65 was investigated in 394 lung cancers (370 nonsmall cell lung carcinomas [NSCLC]; and 24 small cell lung carcinomas [SCLC]) and 269 lung normal epithelium and preneoplastic lesions, including hyperplasias, squamous metaplasias, dysplasias, and atypical adenomatous hyperplasias.

RESULTS

High levels of nuclear immunohistochemical expression of NF-kappaB p65 were detected in the lung cancers, with significantly higher levels in SCLCs compared with NSCLCs (P<.0001). In adenocarcinomas the NF-kappaB p65 expression level was significantly higher in advanced TNM stages (III-IV) than in earlier stages (I-II) (P<.0001), and when NF-kappaB p65 is dichotomized using 50% as the cutoff point (high vs low), a higher NF-kappaB p65 expression level was detected in tumors having either K-RAS (P = .02) or EGFR (P = .009) mutations compared with wildtype tumors. A relatively high level of nuclear NF-kappaB p65 expression was detected in normal and mildly abnormal epithelium, and a progression with increasing histology severity was detected in preneoplastic lesions.

CONCLUSIONS

NF-kappaB p65 nuclear expression is an early and frequent phenomenon in the pathogenesis of lung cancer. The findings indicate that NF-kappaB activation plays an important role in lung cancer pathogenesis and is a suitable target for the development of new lung cancer therapies and chemoprevention strategies.

Preadministration of high-dose salicylates, suppressors of NF-kappaB activation, may increase the chemosensitivity of many cancers: an example of proapoptotic signal modulation therapy

NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.

NF-kappaB activation by double-strand breaks

Cellular response to DNA damage is complex and relies on the simultaneous activation of different networks. It involves DNA damage recognition, repair, and induction of signalling cascades leading to cell cycle checkpoint activation, apoptosis, and stress related responses. The fate of damaged cells depends on the balance between pro- and antiapoptotic signals. In this decisive life or death choice, the transcription factor NF-kappaB has emerged as a prosurvival actor in most cell types. As corollary, it appears to be associated with tumorigenic process and resistance to therapeutic strategies as it protects cancerous cells from death. In this review, we will focus on NF-kappaB activation by double-strand breaks inducing agents, such as ionizing radiation and DNA topoisomerase I and II inhibitors routinely used in cancer therapy. Coinciding with the 20th anniversary of the NF-kappaB discovery, major steps of the DSB-triggered cascade have been recently identified. Two parallel cascades are necessary for NF-kappaB activation. The first one depends on ATM (activated by double-strand breaks) and the second on PIDD (activated by an unknown stress signal). The phosphorylation of NEMO by ATM is the point of convergence of these two cascades. The identification of ATM/NEMO complex as the long searched "nuclear to cytoplasm" signal leading to IKK activation is also a major piece of the puzzle. The knowledge of the precise steps leading to DSB-initiated NF-kappaB activation will allow the development of specific blocking compounds reducing its prosurvival function.

Chemosensitization and radiosensitization of tumors by plant polyphenols

The treatment of cancer with chemotherapeutic agents and radiation has two major problems: time-dependent development of tumor resistance to therapy (chemoresistance and radioresistance) and nonspecific toxicity toward normal cells. Many plant-derived polyphenols have been studied intently for their potential chemopreventive properties and are pharmacologically safe. These compounds include genistein, curcumin, resveratrol, silymarin, caffeic acid phenethyl ester, flavopiridol, emodin, green tea polyphenols, piperine, oleandrin, ursolic acid, and betulinic acid. Recent research has suggested that these plant polyphenols might be used to sensitize tumor cells to chemotherapeutic agents and radiation therapy by inhibiting pathways that lead to treatment resistance. These agents have also been found to be protective from therapy-associated toxicities. How these polyphenols protect normal cells and sensitize tumor cells to treatment is discussed in this review.

HER-2/neu Overexpression Increases the Viable Hypoxic Cell Population within Solid Tumors without Causing Changes in Tumor Vascularization

The effects of HER-2/neu overexpression on the tumor microenvironment in an aggressive breast cancer xenograft model were investigated. These studies focused on tumors derived following the subcutaneous injection of MDA-MB-435/LCC6 cells transfected with human c-erbB2 (LCC6HER-2) into SCID-Rag2M mice. LCC6HER-2 tumors were more viable (H&E-stained tumor sections) than isogenic vector control tumors (LCC6Vector). Correspondingly, a 2.7-fold increase in trypan blue–excluding cells (P = 0.00056) and a 4.8-fold increase in clonogenic cells (P = 0.00146) were noted in cell suspensions derived from disaggregated LCC6HER-2 versus LCC6Vector tumors. Tumor sections stained with the antibody detecting 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide (EF5), a marker of hypoxia, showed a greater fraction of hypoxic tissue in LCC6HER-2 tumors compared with control tumors. Flow cytometric analyses based on viable tumor cells (DNA content ≥ 2N) in cell suspensions from disaggregated tumors confirmed that there were significantly more EF5-positive cells (i.e., hypoxic) in LCC6HER-2 than in LCC6Vector tumors (16.41 ± 8.1% and 5.96 ± 4.1%, respectively; P = 0.0015). Protein levels of phosphorylated (Ser536) nuclear factor-κB p65 were significantly elevated in LCC6HER-2 tumors (P = 0.00048), and a trend in increased hypoxia-inducible factor-1α protein levels was observed in LCC6HER-2 compared with LCC6Vector tumors. Despite the substantial viable hypoxic cell fraction and a 1.7-fold increase of vascular endothelial growth factor protein (P = 0.05) in LCC6HER-2 tumors, no significant differences were found (P &gt; 0.05) between LCC6HER-2 and LCC6Vector vasculature (CD31 staining and Hoechst 33342 perfusion). These results suggest that HER-2/neu overexpression may be linked with overall increased tumor viability and a significant increase in the population of viable hypoxic cells, which is not due to differences in tumor vascularization.

Soy isoflavone phyto-pharmaceuticals in interleukin-6 affections. Multi-purpose nutraceuticals at the crossroad of hormone replacement, anti-cancer and anti-inflammatory therapy

Interleukin-6 is a pleiotropic cytokine which plays a crucial role in immune physiology and is tightly controlled by hormonal feedback mechanisms. After menopause or andropause, loss of the normally inhibiting sex steroids (estrogen, testosterone) results in elevated IL6 levels that are further progressively increasing with age. Interestingly, excessive IL6 production promotes tumorigenesis (breast, prostate, lung, colon, ovarian), and accounts for several disease-associated pathologies and phenotypical changes of advanced age, such as osteoporosis, rheumatoid arthritis, multiple myeloma, neurodegenerative diseases and frailty. In this respect, pharmacological modulation of IL6 gene expression levels may have therapeutical benefit in preventing cancer progression, ageing discomforts and restoring immune homeostasis. Although "plant extracts" are used in folk medicine within living memory, it is only since the 20th century that numerous scientific investigations have been performed to discover potential health-protective food compounds or "nutraceuticals" which might prevent cancer and ageing diseases. About 2000 years ago, Hippocrates already highlighted "Let food be your medicine and medicine be your food". Various nutrients in the diet play a crucial role in maintaining an "optimal" immune response, such that deficient or excessive intakes can have negative consequences on the organism's immune status and susceptibility to a variety of pathologies. Over the last few decades, various immune-modulating nutrients have been identified, which interfere with IL6 gene expression. Currently, a broad range of phyto-pharmaceuticals with a claimed hormonal activity, called "phyto-estrogens", is recommended for prevention of various diseases related to a disturbed hormonal balance (i.e. menopausal ailments and/or prostate/breast cancer). In this respect, there is a renewed interest in soy isoflavones (genistein, daidzein, biochanin) as potential superior alternatives to the synthetic selective estrogen receptor modulators (SERMs), which are currently applied in hormone replacement therapy (HRT). As phyto-chemicals integrate hormonal ligand activities and interference with signaling cascades, therapeutic use may not be restricted to hormonal ailments only, but may have applications in cancer chemoprevention and/or NF-kappaB-related inflammatory disorders as well.