Nuclear factor B (NF-B) and activator protein 1 (AP-1) are key transcription factors that orchestrate expression of many genes involved in inflammation, embryonic development, lymphoid differentiation, oncogenesis, and apoptosis (48, 62). NF-B and AP-1 activities are induced by a plethora of physiological and environmental stimuli (5, 51).The activity of NF-B is regulated by its interaction with the family of NF-B inhibitors known as IB, which results in the formation of inactive NF-B-IB complexes in the cytoplasm (3,4,60). In response to various stimuli, the IB kinase complex (IKK) then phosphorylates the IB bound to the NF-B complexes as substrates (8,36,45,47). The subsequent proteasome-mediated degradation of IB exposes the nuclear localization signal (NLS) of NF-B, which releases the NF-B proteins to be translocated to the nucleus, where they regulate the transcription of specific genes (5, 48).AP-1 is a group of basic leucine zipper (bZIP) transcription factors consisting of the Fos (c-Fos, FosB, Fra1, and Fra2) and Jun (c-Jun, JunB, and JunD) families (54, 62). The predominant forms of AP-1 in most cells are Fos/Jun heterodimers which have a high affinity for binding to an AP-1 site, whereas Jun/Jun homodimers bind to the AP-1 site with low affinity (54,62). A number of studies have shown that serum and growth factors that induce AP-1 do so by activating the extracellular signal-regulated kinase (ERK) subgroup of mitogen-activated protein kinases (MAPKs) (9, 27, 55). These activated members of MAPKs translocate to the nucleus to phosphorylate and thereby transcriptionally activate a subfamily of ETS domain transcription factors known as ternary complex factors (TCFs) that bind to fos promoters (9,27,55,65,80). fos, fosB, and other members of the AP-1 family of transcription factors are mainly regulated at their transcription through serum responsive elements (SREs) in their promoters (57,76). For example, the regulation of c-fos expression is controlled by Elk, a member of TCFs that associates with the serum response factor (SRF) (11,28,49). The elk-1 gene encodes two spliced variants: elk-1 and an alternatively spliced variant known as ⌬elk-1, which is missing the SRF interaction domain and part of the elk-1 DNA binding domain (61). The ⌬Elk-1protein cannot form an SRF-dependent ternary complex with SRE to activate fos transcription (61). However, a variety of experiments have shown that Elk-1 proteins play a central role in the response of cells to many extracellular signals and control the expression of genes involved in cell cycle progression, differentiation, and apoptosis (62, 75). The mechanism by which Elk-1 activates transcription in response to various stimuli has been extensively studied; however, less is known about the regulation of elk-1 gene expression itself.Even though NF-B and AP-1 transcription factors are regulated by different mechanisms, they appear to be activated simultaneously by the same multitude of stimuli (1,19,37,43,71,78). A number of reports also showed that these transcrip...

Most pancreatic cancer patients present with inoperable disease or develop metastases after surgery. Conventional therapies are usually ineffective in treating metastatic disease. It is evident that novel therapies remain to be developed. Transforming growth factor B (TGF-B) plays a key role in cancer metastasis, signaling through the TGF-B type I/II receptors (TBRI/II). We hypothesized that targeting TBRI/II kinase activity with the novel inhibitor LY2109761 would suppress pancreatic cancer metastatic processes. The effect of LY2109761 has been evaluated on soft agar growth, migration, invasion using a fibroblast coculture model, and detachment-induced apoptosis (anoikis) by Annexin V flow cytometric analysis. The efficacy of LY2109761 on tumor growth, survival, and reduction of spontaneous metastasis have been evaluated in an orthotopic murine model of metastatic pancreatic cancer expressing both luciferase and green fluorescence proteins (L3.6pl/GLT). To determine whether pancreatic cancer cells or the cells in the liver microenvironment were involved in LY2109761-mediated reduction of liver metastasis, we used a model of experimental liver metastasis. LY2109761 significantly inhibited the L3.6pl/GLT soft agar growth, suppressed both basal and TGF-B1Àinduced cell migration and invasion, and induced anoikis. In vivo , LY2109761, in combination with gemcitabine, significantly reduced the tumor burden, prolonged survival, and reduced spontaneous abdominal metastases. Results from the experimental liver metastasis models indicate an important role for targeting TBRI/II kinase activity on tumor and liver microenvironment cells in suppressing liver metastasis. Targeting TBRI/II kinase activity on pancreatic cancer cells or the cells of the liver microenvironment represents a novel therapeutic approach to prevent pancreatic cancer metastasis. [Mol Cancer Ther 2008;7(4):829 -40]

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The transcription factor NF-kappaB regulates genes involved in innate and adaptive immune response, inflammation, apoptosis, and oncogenesis. Proinflammatory cytokines induce the activation of NF-kappaB in both transient and persistent phases. We investigated the mechanism for this biphasic NF-kappaB activation. Our results show that MEKK3 is essential in the regulation of rapid activation of NF-kappaB, whereas MEKK2 is important in controlling the delayed activation of NF-kappaB in response to stimulation with the cytokines TNF-alpha and IL-1alpha. MEKK3 is involved in the formation of the IkappaBalpha:NF-kappaB/IKK complex, whereas MEKK2 participates in assembling the IkappaBbeta:NF-kappaB/IKK complex; these two distinct complexes regulate the proinflammatory cytokine-induced biphasic NF-kappaB activation. Thus, our study reveals a novel mechanism in which different MAP3K and IkappaB isoforms are involved in specific complex formation with IKK and NF-kappaB for regulating the biphasic NF-kappaB activation. These findings provide further insight into the regulation of cytokine-induced specific and temporal gene expression.

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The Rel/NF-kappaB transcription factors play a key role in the regulation of apoptosis and in tumorigenesis by controlling the expressions of specific genes. To determine the role of the constitutive activity of RelA in tumorigenesis, we generated pancreatic tumor cell lines that express a dominant negative mutant of IkappaBalpha (IkappaBalphaM). In this report, we show that the inhibition of constitutive NF-kappaB activity, either by ectopic expression of IkappaBalphaM or by treating the cells with a proteasome inhibitor PS-341 which blocks intracellular degradation of IkappaBalpha proteins, downregulates the expression of bcl-xl. We identified two putative NF-kappaB binding sites (kappaB/A and B) in the bcl-xl promoter and found that these two sites interact with different NF-kappaB proteins. p65/p50 heterodimer interacts with kappaB/A site whereas p50/p50 homodimer interacts with kappaB/B. The bcl-xl promoter reporter gene assays reveal that NF-kappaB dependent transcriptional activation is mainly mediated by kappaB/A site, indicating that bcl-xl is one of the downstream target genes regulated by RelA/p50. Both IkappaBalphaM and PS-341 completely abolish NF-kappaB DNA binding activity; however, PS-341, but not ectopic expression of IkappaBalphaM, sensitized cells to apoptosis induced by Taxol. This is due to the Taxol-mediated reactivation of RelA through phosphorylation and degradation of IkappaBbeta and the re-expression of NF-kappaB regulated bcl-xl gene in these cancer cells as ectopic expression of the bcl-xl gene confers resistance to Taxol-induced apoptosis in PS-341 sensitized cells. These results demonstrate the important function of various NF-kappaB/IkappaB complexes in regulating anti-apoptotic genes in response to apoptotic stimuli, and they raise the possibility that NF-kappaB : IkappaBalpha and NF-kappaB : IkappaBbeta complexes are regulated by different upstream activators, and that NF-kappaB plays a key role in pancreatic tumorigenesis.

Bile duct injury (BDI) during laparoscopic cholecystectomy (LC) which may result in patient disability or death are reported to occur more frequently when compared to open surgery. The aim of this nationwide prospective study beyond the laparoscopic learning curve was to analyze the incidence, risk factors, and management of major BDI. During a 3-year period (1995-1997) 130 items of all LC data were collected on a central computer system from 84 surgical institutions in Switzerland by the Swiss Association of Laparoscopic and Thoracoscopic Surgery and evaluated for major BDIs. Simple biliary leakage was excluded from analysis. There were 12,111 patients with a mean age of 55 years (3-98 years) enrolled in the study. The overall BDI incidence was 0.3%, 0.18% for symptomatic gallstones, and 0.36% for acute cholecystitis. In cases of severe chronic cholecystitis with shrunken gallbladder, the incidence was as high as 3%. Morbidity and mortality rates were significantly increased in BDIs. BDI was recognized intraoperatively in 80.6%, in 64% of cases by help of intraoperative cholangiography. Immediate surgical repair was performed laparoscopically (suture or T-drainage) in 21%; in 79%, open repair (34% simple suture, 66% Roux-en-Y reconstruction) was needed. The BDI incidence did not decrease during the last 7 years. In 47%, BDIs were caused by experienced laparoscopic surgeons, perhaps because they tend to operate on more difficult patients. In conclusion, the incidence of major BDIs remains constant in Switzerland at a level of 0.3%, which is still higher when compared to open surgery. However, most cases are now detected intraoperatively and immediately repaired which ensures a good long-term outcome. For preventing such injuries, exact anatomical knowledge with its variants and a meticulous surgical dissecting technique especially in case of acute inflammation or shrunken gallbladder are mandatory.

Both pro-and antiapoptotic activities of NF-B transcription factor have been observed; however, less is known about the mechanism by which NF-B induces apoptosis. To elucidate how NF-B regulates proapoptotic signaling, we performed functional analyses using wild-type, ikk1؊/؊ , ikk2 ؊/؊ , rela ؊/؊ murine fibroblasts, MDAPanc-28/Puro, MDAPanc-28/IB␣M, and HCT116/p53 ؉/؉ and HCT116/p53 ؊/؊ cells with investigational anticancer agent doxycycline as a superoxide inducer for generating apoptotic stimulus. In this report, we show that doxycycline increased superoxide generation and subsequently activated NF-B, which in turn up-regulated p53 expression and increased the stability and DNA binding activity of p53. Consequently, NF-Bdependent p53 activity induced the expression of p53-regulated genes PUMA and p21 waf1 as well as apoptosis. Importantly, lack of RelA, IKK, and p53 as well as expression of a dominant negative IB␣ (IB␣M) inhibited NF-B-dependent p53 activation and apoptosis. The doxycycline-induced NF-B activation was not inhibited in HCT116/p53 ؊/؊ cells. Our results demonstrate that NF-B plays an essential role in activation of wild-type p53 tumor suppressor to initiate proapoptotic signaling in response to overgeneration of superoxide. Thus, these findings reveal a mechanism of NF-B-regulated proapoptotic signaling.