Inhibition of interferon-gamma-activated nuclear factor-kappa B by cyclosporin A: A possible mechanism for synergistic induction of apoptosis by interferon-gamma and cyclosporin A in gastric carcinoma cells

Cervical Cancer HeLa Cell Autocrine Apoptosis Induced by Coimmobilized IFN-γ plus TNF-α Biomaterials

Using external methods to induce the death of cancer cells is recognized as one of the main strategies for cancer treatment. Research indicated that TNF-α is frequently used in tumor biotherapy while IFN-γ can directly inhibit tumor cell proliferation. In our study, TNF-α and IFN-γ were coimmobilized on polystyrene material (PSt) or Fe₃O₄-oleic acid nanoparticles (NPs). Then the structural change of these two proteins can be observed. Meanwhile, the expressions of both TNF-α and IFN-α increased significantly, as determined by gene microarray analysis; however, in the presence of TNF-α plus IFN-α inhibitors, TNF-α and IFN-α did not increase in HeLa cells induced by coimmobilized IFN-γ plus TNF-α. Our results indicate that such change can stimilate HeLa cells to secrete more TNF-α and IFN-α, by which the apoptosis of HeLa cells could be further induced. This study is the first report of autocrine-induced apoptosis of HeLa cells. In addition, we performed ELISA, RT-PCR, flow cytometry, and Western blot analyses, as well as a series of analytical tests at the animal level. our data also indicate that the PSt-coimmobilized IFN-γ plus TNF-α has apparent effects for cancer treatment in vivo, which is of great significance for translation into clinical medicine.

NF-κB and targeted therapy of gastric cancer: recent research progress

Gastric cancer is a main cause of cancer death worldwide. Despite the knowledge that Helicobacter pylori constitutes the main cause of gastric cancer, the mechanisms for gastric carcinogenesis are still elucidated. 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 tumorigenesis. Nuclear factor-kappaB (NF-κB) is a major cell survival signal. Recent studies with cell culture systems and animal models have certified the links between NF-κB and gastric carcinogenesis and resistance to chemotherapy. Inhibition of NF-κB activation can enhance the sensitivity of cancer cells to chemotherapeutic drugs. In this review, we summarize recent progress in understanding the role of the NF-κB pathway in gastric cancer development as well as in modulating NF-κB for gastric cancer prevention and therapy.

The antagonistic effect between STAT1 and Survivin and its clinical significance in gastric cancer

In previous studies, we observed that STAT1 and Survivin correlated negatively with gastric cancer tissues, and that the functions of the IFN-γ-STAT1 pathway and Survivin in gastric cancer are the same as those reported for other types of cancer. In this study, the SGC7901 gastric cancer cell line and 83 gastric cancer specimens were used to confirm the relationship between STAT1 and Survivin, as well as the clinical significance of this relationship in gastric cancer. IFN-γ and STAT1 and Survivin antisense oligonucleotides (ASONs) were used to knock down the expression in SGC7901 cells. The protein expression of STAT1 and Survivin was tested by immunocytochemical and image analysis methods. A gastric cancer tissue microarray was prepared and tested by immunohistochemical methods. Data were analyzed by the Spearman's rank correlation analysis, the χ(2) test and Cox's multivariate regression analysis. Upon knockdown of IFN-γ, STAT1 and Survivin expression by ASON in the SGC7901 cell line, an antagonistic effect was observed between STAT1 and Survivin. In gastric cancer tissues, STAT1 showed a negative correlation with depth of invasion (p<0.05) in gastric cancer tissues exhibiting a negative Survivin protein expression. Furthermore, in tissues exhibiting a negative STAT1 protein expression, Survivin correlated negatively with N stage (p<0.05). Pathological and molecular markers were used to conduct Cox's multivariate regression analysis, and depth of invasion and N stage were found to be prognostic factors (p<0.05). On the other hand, in tissues exhibiting a negative Survivin protein expression, Cox's multivariate regression analysis revealed that the differentiation type and STAT1 protein expression were prognostic factors (p<0.05). There is an antagonistic effect between STAT1 and Survivin in gastric cancer, and this antagonistic effect is of clinical significance in gastric cancer.

IFN-γ regulates P53 expression in gastric cancer through a STAT1-independent pathway

AIM: To explore the relationship between STAT1 and p53 mRNA expression in human gastric cancer cell line SGC7901 and to characterize the regulatory effect of interferon-γ (IFN-γ) on p53 expression in gastric cancer.

METHODS: After SGC7901 cells were treated with IFN-γ and antisense oligonucleotides (ASON) targeting the STAT1 gene, alone or in combination, the mRNA expression of p53 and STAT1 was tested by RT-PCR, and cell apoptosis was examined by Hoechst 33258 staining. The protein expression of p53 and STAT1 in human gastric cancer tissue was examined by immunohistochemistry. Average optical density was compared between different groups using Student's t test analysis. The relationship between the expression of STAT1 and P53 protein in human gastric cancer was evaluated using Spearman rank correlation analysis.

RESULTS: Treatment with IFN-γ up-regulated the mRNA expression of STAT1 and p53 in SGC7901 cells (both P < 0.05). Treatment with STAT1-specific ASON induced down-regulation of STAT1 mRNA expression (P < 0.05) in a concentration-dependent manner. The expression of p53 mRNA was lower in all ASON groups than in the control group (all P > 0.05). Simultaneous treatment with IFN-γ and STAT1-specific ASON induced lower STAT1 mRNA expression than treatment with IFN-γ alone (P < 0.05). The mRNA expression of p53 was higher in all cells treated simultaneously with IFN-γ and STAT1-specific ASON than in those treated with IFN-γ alone (all P > 0.05). There was no correlation between STAT1 and p53 mRNA and protein expression in human gastric cancer tissue and cell lines. Treatment with either IFN-γ or STAT1-specific ASON had no significant impact on cell apoptosis.

CONCLUSION: IFN-γ could regulate p53 expression in gastric cancer through a STAT1-independent pathway.

Molecular mechanisms of IFN-gamma to up-regulate MHC class I antigen processing and presentation

IFN-gamma up-regulates MHC class I expression and antigen processing and presentation on cells, since IFN-gamma can induce multiple gene expressions that are related to MHC class I antigen processing and presentation. MHC class I antigen presentation-associated gene expression is initiated by IRF-1. IRF-1 expression is initiated by phosphorylated STAT1. IFN-gamma binds to IFN receptors, and then activates JAK1/JAK2/STAT1 signal transduction via phosphorylation of JAK and STAT1 in cells. IFN-gamma up-regulates MHC class I antigen presentation via activation of JAK/STAT1 signal transduction pathway. Mechanisms of IFN-gamma to enhance MHC class I antigen processing and presentation were summarized in this literature review.

IRF-1 transcriptionally upregulates PUMA, which mediates the mitochondrial apoptotic pathway in IRF-1-induced apoptosis in cancer cells

Interferon Regulatory Factor-1 (IRF-1) is a transcription factor which acts as a tumor suppressor and causes apoptosis in cancer cells. We evaluated IRF-1 induced apoptosis in gastric cancer cell lines. We established stable clones in AGS cells that have a tetracycline inducible IRF-1 expression system. We used these clones and recombinant adenovirus expressing IRF-1 to explore the mechanism of IRF-1 induced apoptosis in gastric cancer. Expression of IRF-1 causes apoptosis in gastric cancer cell lines as demonstrated by phosphatidylserine exposure and cleavage of caspase-8, caspase-3, and Bid with mitochondrial release of cytochrome c. However, inhibition of caspase-8 and Bid did not inhibit apoptosis and did not decrease cleaved caspase-9 or mitochondrial release of cytochrome c. We then demonstrate that IRF-1 up-regulates PUMA (p53 up-regulated modulator of apoptosis), that is known to activate apoptosis by the intrinsic pathway; this can be p53 independent. IRF-1 binds to distinct sites in the promoter of PUMA and activates PUMA transcription. Moreover, molecular markers of mitochondrial apoptosis are eliminated in PUMA knockout and knockdown cells and phospatidylserine exposure is decreased dramatically. Finally, we demonstrate that IFN-γ induces IRF-1 mediated up-regulation of PUMA in cancer cells. We conclude that IRF-1 can induce apoptosis by the intrinsic pathway independent of the extrinsic pathway by up-regulation of PUMA.

Clinical significance of serum interferon-γ and signal transducer and activator of transcription 1 in patients with gastric carcinoma

AIM: To determine serum interferon-γ (IFN-γ) and signal transducer and activator of transcription 1 (STAT1) levels and analyze their correlation with clinical and pathological parameters in patients with gastric carcinoma.

METHODS: Forty-two patients with gastric carcinoma and 40 healthy controls were included in the study. Serum IFN-γ and STAT1 levels were measured by enzyme-linked immunosorbent assay (ELISA). Analysis of variance (ANOVA) and Spearman correlation analysis were performed to investigate the correlation of IFN-γ and STAT1 expression with pathological type, pathological stage and TNM stage of gastric carcinoma.

RESULTS: Serum IFN-γ and STAT1 levels were significantly lower in patients with gastric carcinoma than in healthy controls (t = -10.587 and -8.711, respectively; both P = 0.000). In patients with gastric carcinoma, serum IFN-γ level was significantly different between patients with signet ring cell carcinoma and grade II-III adenocarcinoma (t = 0.374, P = 0.023). Serum IFN-γ and STAT1 levels showed no significant differences among patients with gastric carcinoma of different pathological types or at different pathological or TNM stages. Spearman correlation analysis showed that serum IFN-γ and STAT1 levels had no significant correlation with pathological type, pathological stage and TNM stage of gastric carcinoma.

CONCLUSION: Serum IFN-γ and STAT1 levels are closely related to the development of gastric carcinoma. Combined detection of serum IFN-γ and STAT1 levels is helpful for diagnosis of gastric carcinoma.

Interferon-gamma-dependent tyrosine phosphorylation of MEKK4 via Pyk2 is regulated by annexin II and SHP2 in keratinocytes

IFNgamma (interferon-gamma) binding to its cognate receptor results, through JAK (Janus kinase), in direct activation of receptor-bound STAT1 (signal transducer and activator of transcription 1), although there is evidence for additional activation of a MAPK (mitogen-activated protein kinase) pathway. In the present paper, we report IFNgamma-dependent activation of the MEKK4 (MAPK/extracellular-signal-regulated kinase kinase kinase 4) pathway in HaCaT human keratinocytes. MEKK4 is tyrosine-phosphorylated and the IFNgamma-dependent phosphorylation requires intracellular calcium. Calcium-dependent phosphorylation of MEKK4 is mediated by Pyk2. Moreover, MEKK4 and Pyk2 co-localize in an IFNgamma-dependent manner in the perinuclear region. Furthermore, the calcium-binding protein, annexin II, and the calcium-regulated kinase, Pyk2, co-immunoprecipitate with MEKK4 after treatment with IFNgamma. Immunofluorescence imaging of HaCaT cells shows an IFNgamma-dependent co-localization of annexin II with Pyk2 in the perinuclear region, suggesting that annexin II mediates the calcium-dependent regulation of Pyk2. Tyrosine phosphorylation of MEKK4 correlates with its activity to phosphorylate MKK6 (MAPK kinase 6) in vitro and subsequent p38 MAPK activation in an IFNgamma-dependent manner. Additional studies demonstrate that the SH2 (Src homology 2)-domain-containing tyrosine phosphatase SHP2 co-immunoprecipitates with MEKK4 in an IFNgamma-dependent manner and co-localizes with MEKK4 after IFNgamma stimulation in the perinuclear region in HaCaT cells. Furthermore, we provide evidence that SHP2 dephosphorylates MEKK4 and Pyk2, terminating the MEKK4-dependent branch of the IFNgamma signalling pathway.

Role of IFN-γ-STAT1 pathway in human gastric adenocarcinoma

AIM: To investigate relationships among STAT1, Caspase-7 and p21^waf in gastric adenocarcinoma tissue and gastric adenocarcinoma cell SGC7901, and to shed light on features of IFN-γ-STAT1 pathway in gastric adenocarcinoma.

METHODS: Gastric adenocarcinoma tissue was tested by immunohistochemical method. SGC7901 cell was treated with IFN-γ and STAT1 antisense oligonucleotides, and mRNA and protein expression was detected using RT-PCR, immunocytochemistry and image analysis methods. Apoptosis was determined by Hoechest 33258.

RESULTS: Caspase-7 was positive correlation with STAT1 and p21^waf (r = 0.32, 0.22, both P < 0.05) in gastric adenocarcinoma tissue. IFN-γ promoted mRNA and protein expression of STAT1, Caspase-7 and p21^waf was up-regulated in SGC7901 cell (P < 0.05). After treatment with IFN-γ along with varied concentrations of STAT1 antisense oligonucleotides, significantly lower STAT1 mRNA and protein expression was observed than IFN-γ used alone in SGC7901 cells, which showed a concentration-dependent manner (P < 0.05); significantly lower Caspase-7 and P21^waf protein expression was observed than IFN-γ used alone in SGC7901 cell in a concentration-dependent manner (P < 0.05). However, mRNA expression of Caspase-7 was down-regulated first and then up-regulated, while mRNA expression of p21waf was up-regulated first and then down-regulated.

CONCLUSION: There is a IFN-γ-STAT1 pathway in gastric adenocarcinoma tissue and SGC7901 cell line. IFN-γ-STAT1 could up-regulate the expression of Caspase-7 and p21^waf in gastric adenocarcinoma, but could not induce apoptosis. The downstream molecular of IFN-γ- STAT1 pathway has different expression features in mRNA and protein expression level in gastric adenocarcinoma.

Coexposure of mice to trovafloxacin and lipopolysaccharide, a model of idiosyncratic hepatotoxicity, results in a unique gene expression profile and interferon gamma-dependent liver injury

The antibiotic trovafloxacin (TVX) has caused severe idiosyncratic hepatotoxicity in people, whereas levofloxacin (LVX) has not. Mice cotreated with TVX and lipopolysaccharide (LPS), but not with LVX and LPS, develop severe hepatocellular necrosis. Mice were treated with TVX and/or LPS, and hepatic gene expression changes were measured before liver injury using gene array. Hepatic gene expression profiles from mice treated with TVX/LPS clustered differently from those treated with LPS or TVX alone. Several of the probe sets expressed differently in TVX/LPS-treated mice were involved in interferon (IFN) signaling and the janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway. A time course of plasma concentrations of IFN-gamma and interleukin (IL)-18, which directly induces IFN-gamma production, revealed that both cytokines were selectively increased in TVX/LPS-treated mice. Both IL-18(-/-) and IFN-gamma(-/-) mice were significantly protected from TVX/LPS-induced liver injury. In addition, IFN-gamma(-/-) mice had decreased plasma concentrations of tumor necrosis factor-alpha, IL-18, and IL-1beta when compared to wild-type mice. In conclusion, the altered expression of genes involved in IFN signaling in TVX/LPS-treated mice led to the finding that IL-18 and IFN-gamma play a critical role in TVX/LPS-induced liver injury.

Ad-IRF-1 induces apoptosis in esophageal adenocarcinoma

The nuclear transcription factor interferon regulatory factor-1 (IRF-1) is a putative tumor suppressor, but the expression and function of IRF-1 in esophageal adenocarcinoma (EA) remain unknown. We hypothesized that IRF-1 expression was reduced or lost in EA and that restoration of IRF-1 would result in the apoptosis of EA cells in vitro and the inhibition of tumor growth in vivo. Three EA cell lines were used to examine IRF-1 expression, IFN-gamma responsiveness, and the effects of IRF-1 overexpression using a recombinant adenoviral vector (Ad-IRF-1). All three EA cell lines produced IRF-1 protein following IFN-gamma stimulation, although IFN-gamma did not induce cell death. In contrast, Ad-IRF-1 infection resulted in high levels of IRF-1 protein and triggered apoptosis in all three EA cell lines. Potential mechanisms for the differential response to IFN-gamma versus Ad-IRF-1--such as modulation of c-Met or extracellular regulated kinase signaling, or altered expression of IRF-2, Fas, or survivin--were investigated, but none of these mechanisms can account for this observation. In vivo administration of IRF-1 in a murine model of EA modestly inhibited tumor growth, but did not lead to tumor regression. Strategies aimed at increasing or restoring IRF-1 expression may have therapeutic benefits in EA.

Amniotic membrane induces apoptosis of interferon-gamma activated macrophages in vitro

Amniotic membrane (AM) used as a temporary or permanent graft for ocular surface reconstruction has a potent anti-inflammatory effect. We would like to investigate the mechanism whereby AM induces macrophage apoptosis in vitro. Mouse macrophages, Raw 264.7 cells, were cultured on plastic, type I collagen, corneal stromal slice or AM stromal matrix in serum-free medium with or without interferon-gamma (IFN-gamma). Cells were stained by LIVE/DEAD assay, Hoechst-33342, and TUNEL assay for cell death and apoptosis. Cell lysates and conditioned media were analysed by Cell Death Detection ELISA assay for quantitation of apoptosis. Conditioned media were also analysed by Griess assay for the nitrite concentration and ELISA assay for tumour necrosis factor alpha (TNF-alpha) concentration. Lysates of cells were subjected to Western blot analyses of IKK-alpha, IKK-beta, p65 (RelA) subunit of nuclear factor kappaB (NF-kappaB), total Akt, phospho-Akt (Ser473), and phospho-FKHR (Thr24)/phosphor-FKHRL1 (Thr32). At 48hr after cultivation, cells showed a low level of apoptosis when cultured on plastic, type I collagen and corneal stromal slice with or without IFN-gamma and on AM without IFN-gamma. Nevertheless, cells showed a significant increase of apoptosis when cultured on AM with IFN-gamma activation, and this phenomenon became apparent only after 48 hr. IFN-gamma-activated macrophages on plastic continuously produced nitric oxide (NO) and TNF-alpha during 72 hr culturing. In contrast, there was no NO and TNF-alpha production after 48 hr culture on AM. NO inhibitors, L-NMMA and L-NIL, attenuated NO production of IFN-gamma-activated macrophages on AM, while apoptosis was not decreased accordingly. Expression of IKK-alpha, IKK-beta, p65 (RelA) subunit of NF-kappaB total Akt, phosopho-Akt (Ser473), and phospho-FKHR (Thr24)/FKHRL1 (Thr32) was all down-regulated in IFN-gamma-activated macrophages cultured on AM. In conclusion, AM stromal matrix induces apoptosis of IFN-gamma activated, but not non-activated macrophages, not through the generation of NO, but instead by down-regulating anti-apoptotic NF-kappaB and Akt-FKHR signalling pathways.

NF-κB as a molecular target in adjuvant therapy of gastrointestinal carcinomas

AIM

To describe the role of nuclear factor-kappa B (NF-kappaB) in cancer treatment.

METHODS

We searched the Pubmed database (until Oct, 2004) with the keywords of gastrointestinal carcinoma, NF-kappaB, inhibitor, cancer treatment molecular target and chemoresistance. We reviewed the literature in the role of NF-kappaB activation in chemoresistance, tumour growth suppression and enhancement of apoptosis in gastrointestinal carcinomas.

CONCLUSIONS

Several possible strategies for inhibiting NF-kappaB activation are identified. The importance of targeting NF-kappaB as a potential therapeutic approach in clinical medicine was discussed.

Stat1-independent induction of SOCS-3 by interferon-gamma is mediated by sustained activation of Stat3 in mouse embryonic fibroblasts

Using microarray technology, we previously demonstrated that IFN-gamma induces suppressor of cytokine signaling-3 (SOCS-3) in Stat1-/- mouse embryonic fibroblasts and bone marrow-derived macrophages. In this study, we have investigated the mechanism by which SOCS-3 is induced by Stat1-independent signal transduction pathway. Tyrosine kinases Jak1 and Jak2 are required for SOCS-3 induction by IFN-gamma in mouse embryonic fibroblasts. IFN-gamma stimulated strong and sustained activation of Stat1 whereas Stat3 activation was weak and transient in wild-type fibroblasts. In contrast, Stat3 is activated strongly and in a sustained manner in Stat1-/- fibroblasts. The Src kinase inhibitor SU6656 suppressed IFN-gamma activation of Stat3 in both wild-type and Stat1-/- fibroblasts. However, SU6656 inhibited IFN-gamma induction of SOCS-3 completely in Stat1-/- but not in wild-type fibroblasts. Knock down of Stat3 by short interfering RNA abrogated Stat3 activation and SOCS-3 induction by IFN-gamma in Stat1-/- fibroblasts. In human fibrosarcoma cell line 2fTGH, IFN-gamma activated Stat1 but not Stat3. SOCS-3 induction by IFN-gamma is strictly Stat1-dependent. The Stat1 docking site is required for SOCS-3 induction by IFN-gamma in human lung adenocarcinoma cells. We propose a model in which sustained activation of Stat1 or Stat3 mediates SOCS-3 induction by IFN-gamma in wild-type and Stat1-/- mouse embryonic fibroblasts, respectively.

Interleukin 1beta enhances invasive ability of gastric carcinoma through nuclear factor-kappaB activation

PURPOSE

We examined the role of interleukin (IL)-1beta in activation of nuclear factor kappaB (NF-kappaB) and the biological function of activated NF-kappaB in gastric carcinoma cells.

EXPERIMENTAL DESIGN

Human gastric carcinoma cell line GCTM-1 was used to examine NF-kappaB activation by immunostaining and electrophoretic mobility shift assay. Matrix metalloproteinase (MMP)-9 expression, which plays an important role in tumor invasion, was assessed by semiquantitative reverse transcription-PCR, Western blotting, and immunostaining. The invasive ability of GCTM-1 cells was measured by Matrigel invasion assay. In vivo expression of IL-1beta and MMP-9 and activation of NF-kappaB in 10 surgically resected gastric carcinoma specimens were examined immunohistochemically.

RESULTS

IL-1beta enhanced NF-kappaB activation, MMP-9 expression, and the invasive ability of GCTM-1. A NF-kappaB inhibitor, pyrrolidine dithiocarbamate, suppressed both MMP-9 expression and invasiveness of IL-1beta-treated GCTM-1 cells. IL-1beta did not increase the invasive ability of GCTM-1 cells transfected with MMP-9 antisense oligonucleotide. Concomitant expression of IL-1beta and nuclear NF-kappaB was observed in 3 of 10 gastric carcinoma specimens. Cells producing IL-1beta were tumor-infiltrating macrophages in two specimens and gastric carcinoma cells in one specimen.

CONCLUSIONS

One of the molecules that may play a role in NF-kappaB activation in some gastric carcinomas is IL-1beta. The present results suggest that IL-1beta increases the invasive ability of carcinoma cells through activation of NF-kappaB and the resulting MMP-9 expression.