Abstract B199: Transcriptional regulation of KLF4 by Yin Yang 1 (YY1) in pediatric B-NHL and clinical significance

Krüppel-like factor 4 (KLF4) is a member of the KLF zinc-finger containing transcription factor family. Supporting evidence has established that KLF4 is either an oncogene or a tumor suppressor. Reported studies have indicated the involvement of KLF4 in the regulation of apoptosis, proliferation, and differentiation of B cells and B-cell malignancies. In contrast to adult lymphomas and solid tumors, recently, we have shown in a TMA the overexpression of KLF4 in pediatric NHL tumor tissues. The KLF4 overexpresion predicted unresponsiveness to CHOP treatment. In addition, we have also reported that the transcription factor Yin Yang 1 (YY1) is overexpressed in B-NHL and is a prognostic factor. We hypothesized that the coexpression of KLF4 and YY1 may result from the transcriptional regulation of KLF4 by YY1. This hypothesis was tested in various experimental designs both in cell lines and tumor tissues derived from patients. Analysis of the B-NHL cell line Ramos revealed that both KLF4 and YY1 are overexpressed compared to normal B cells. The transfection of Ramos with siRNA YY1 showed significant inhibition of KLF4. In silico analyses of the KLF4 promoter identified the presence of four putative binding sites for YY1. We confirmed that the -126 site as the binding site for YY1 by CHIP analysis. We also used a reporter system of the KLF4 promoter and mutated the putative binding site for YY1 (-126) and confirmed it as an important site for the regulation of KLF4. The coexpressions of KLF4 and YY1 were examined in TMA of pediatric lymphomas and showed by IHC that all of the tumor tissues exhibited a positive correlation between the expression of KLF4 and YY1 and the correlation was markedly significant in the Burkitt subtype. KLF4 acts as a transcriptional activator of epithelial genes and as a repressor of mesenchymal genes. In addition, KLF4 suppresses the extrinsic apoptotic pathway by inhibiting the activation and cleavage of caspases (7, 9, and 3). Thus, the overexpression of KLF4 in lymphoma may be responsible, in part, in the pathogenesis, malignancy, and drug resistance. The present findings suggest that both KLF4 and YY1 are prognostic biomarkers in pediatric lymphoma. Further, inhibitors of KLF4 are being clinically tested and may be applicable in the treatment of lymphoma.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B199.

Citation Format: Mario I. Vega, Alberto Valencia-Hipolito, Miriam Hernández-Atenógenes, Gabriel G. Vega, Hector Mayani, Sara Huerta-Yepez, Benjamin Bonavida. Transcriptional regulation of KLF4 by Yin Yang 1 (YY1) in pediatric B-NHL and clinical significance. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B199.

Nordihydroguaiaretic acid induces Nrf2 nuclear translocation in vivo and attenuates renal damage and apoptosis in the ischemia and reperfusion model

It has been shown that the pretreatment with nordihydroguaiaretic acid (NDGA), a lignan with direct and indirect antioxidant properties, protects against the ischemia-reperfusion (I/R)-induced renal oxidant damage. Although it has been shown that NDGA induces Nrf2 nuclear translocation in renal epithelial LLC-PK1 cells in culture, it is unknown if NDGA may induce Nrf2 translocation in vivo. In this work was explored if NDGA is able to induce in vivo Nrf2 nuclear translocation in kidneys of rats submitted to uni-nephrectomy (U-NX) or I/R injury. Four groups of male Wistar rats were used: U-NX, NDGA, I/R, and I/R+NDGA. NDGA was injected i.p. (10mg/kg/day) starting 48 h before I/R. Kidney samples were obtained at 3 h of reperfusion after to measure Nrf2 translocation. Additional groups of rats were studied at 24 h of reperfusion to measure histological damage and apoptosis. NDGA was able to induce Nrf2 translocation in vivo in kidneys of rats submitted to both U-NX and I/R injury and to protect against renal histological damage and apoptosis. It is concluded that the pretreatment of NDGA is able to induce in vivo nuclear Nrf2 translocation in kidney of rats suggesting that this may be involved in the renoprotection against I/R.

Roles Each of Snail, Yin Yang 1 and RKIP in the Regulation of Tumor Cells Chemo-immuno-resistance to Apoptosis

The current anti-cancer therapeutic armamentarium consists of surgery, chemotherapy, radiation, hormonal therapy, immunotherapy, and combinations thereof. Initial treatments usually result in objective clinical responses with prolongation of overall survival (OS) and progression-free survival (PFS) in a large subset of the treated patients. However, at the onset, there is a subset of patients who does not respond and another subset that initially responded but experiences relapses and recurrences. These latter subsets of patients develop a state of cross-resistance to a variety of unrelated therapies. Therefore, there is an urgent need to first unravel the underlying mechanisms of resistance and associated gene products that regulate the cross-resistance. Such gene products are potential therapeutic targets as well as potential prognostic/diagnostic biomarkers. In this context, we have identified three interrelated gene products involved in resistance, namely, Snail, YY1, and RKIP that are components of the dysregulated NF-κB/Snail/YY1/RKIP loop in many cancers. In this review, we will discuss the roles each of Snail, YY1 and RKIP in the regulation of tumor cell resistance to chemo and immunotherapies. Since these same gene products have also been shown to be involved in the regulation of the EMT phenotype and metastasis, we suggest that targeting any of these three gene products can simultaneously inhibit tumor cell resistance and metastasis.

Contribution of either YY1 or BclXL-induced inhibition by the NO-donor DETANONOate in the reversal of drug resistance, both in vitro and in vivo. YY1 and BclXL are overexpressed in prostate cancer

Nitric oxide (NO) donors have been shown to activate or inhibit constitutively-activated survival/anti-apoptotic pathways, such as NF-κB, in cancer cells. We report here that treatment of drug-resistant human prostate carcinoma cell lines with high levels (500-1000 μM) of the NO-donor DETANONOate sensitized the resistant tumor cells to apoptosis by CDDP and the combination was synergistic. We hypothesized that DETANONOate inhibits previously identified NF-κB-regulated resistant factors such as Yin Yang 1 (YY1) and Bcl-2/BclXL. Lysates from tumor cells treated with DETANONOate showed inhibition of YY1 and BclXL expressions. Transfection with either YY1 or BclXL siRNA resulted in the inhibition of both YY1 and BclXL expressions and sensitized the cells to CDDP apoptosis. Mice bearing PC-3 tumor xenografts and treated with the combination of DETANONOate and CDDP resulted in significant inhibition of tumor growth; treatment with single agent alone did not have any effect on tumor growth. Analysis of patients TMA tissues with prostatic cancer revealed higher expression of both YY1 and BclXL as a function of tumor grades and their levels were directly correlated. Thus, both YY1 and BclXL are potential prognostic biomarkers. Overall, the above findings suggest that one mechanism of DETANONOate-induced sensitization of resistant tumor cells to CDDP correlated with the inhibition of NF-κB and its targets YY1 and BclXL. The examination of the combination of NO donors and cytotoxic therapy in the treatment of resistant prostate cancer may be warranted.

Casein induces the proliferation of bone marrow mononuclear cells, apoptosis of WEHI-3 leukaemic cells and increased survival in a leukaemia mouse model

Acute myeloid leukaemia results from the neoplastic transformation of haematopoietic stem cells. Although advances have been made in its treatment, the mortality rate remains high. As a result, therapeutic alternatives continue to be explored. In this study, we present evidence that suggests that casein, the principal protein in milk, possesses significant antileukaemic properties. We investigated whether casein inhibited the in vitro proliferation and induced the apoptosis of the mouse myelomonocytic leukaemia cell line WEHI-3. By contrast, under identical conditions, casein markedly promotes the proliferation of mouse normal mononuclear bone marrow cells. Since the selective elimination of leukaemia cells is an ideal therapeutic strategy, we also evaluated the antileukaemic potential of casein in vivo. The results showed that casein increases the survival of mice bearing WEHI-3-induced tumours, suggesting that this molecule is also capable of inhibiting the proliferation of these cells in vivo. The evidence that casein inhibited cell proliferation and induced apoptosis in leukaemia cells in vitro, but increased survival in vivo in a leukaemia mouse model, indicates that casein may be useful in leukaemia therapy.

Abstract 766: Galiximab disrupts the dysregulated NF-κB/YY1/Snail/BclXL circuit that regulates the resistance of B-NHL cell lines: Sensitization to chemo-immunotherapeutic drugs

The combination of Rituximab and chemotherapy is currently the standard treatment for several B-NHL malignancies. However, there is a subset of patients that does not initially respond and a subset that fails to respond to further treatment. Therefore, there is an urgent need to develop new therapeutic modalities for those patients. Galiximab (anti-CD80 mAb) has been developed with the objective of overcoming the resistance to rituximab and/or used in combination with rituximab to improve response rates. A Phase II double blind placebo controlled trial of rituximab+galiximab vs. rituximab+placebo in 337 subjects with relapsed or refractory, grade I-IIIa, follicular NHL in relapse were followed up of 13.8 month. The addition of Galiximab to rituximab reduced the hazard for disease progression or death by 26% compared to the rituximab+placebo group. However, the mechanisms by which Galiximab mediates its effects have not been examined. Preliminary findings demonstrated that treatment of B-NHL cell lines with Galiximab resulted in the inhibition of cell growth and sensitization of drug-resistant tumor cells to both CDDP and TRAIL-mediated apoptosis. Sensitization was a result of Galiximab-induced inhibition of the constitutively activated NF-κB pathway and downstream the resistant factors Yin Yang 1 (YY1), Snail, and BclXL. The role of each of these factors in the regulation of resistance and whether they also regulate each other were assessed by transfection with siRNAs. Treatment of Raji (CD80+) Burkitt's Lymphoma cell line with YY1 siRNA resulted in the inhibition of YY1, Snail, phospho-p65, and BclXL as assessed by western. Likewise, transfection with Snail siRNA resulted in the inhibition of Snail, YY1, phospho-p65, and BclXL. In both cases, the transfected cells resulted in the reversal of resistance and sensitization to apoptosis by both CDDP and TRAIL. These findings revealed that NF-κB regulates YY1, Snail, and BclXL and that both YY1 and Snail, in turn, regulate NF-κB and BclXL. It has been reported that YY1 regulates NF-κB via miR29 and, in turn, NF-κB regulates YY1 transcription. Also, YY1 regulates Snail transcription. However, it is not known how does Snail regulate NF-κB and YY1. We speculate that Snail regulates phospho-p65 via transcription or indirectly through the regulation of NF-κB by YY1. The present findings reveal a new dysregulated NF-κB/YY1/Snail/BclXL circuit in the regulation of resistance of B-NHL to cytotoxic drugs. Galiximab interferes with this circuit and results in the reverse of resistance. In addition, the findings revealed new targets that may be of prognostic significance as well as targets for therapy. The present findings in B-NHL cell lines may be also generalized to non-lymphoid malignancies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 766. doi:1538-7445.AM2012-766

Abstract 4330: Transcriptional regulation of gp170 by YY1 and prognostic significance in childhood acute lymphoblastic leukemia (ALL)

Leukemia is the most common cancer among children under the age of 15 years in the United States and many developed countries. In recent years, there has been the emergence of novel therapeutic drugs for this disease. However, the development of drug resistance by the tumor cells remains the most important obstacle in the treatment of leukemia. A widely studied mechanism of tumor resistance to chemotherapeutic drugs is through the expression of the multi-drug resistance (MDR) genes. P-glycoprotein 170 (gp170) is an MDR1 gene product which serves as an ATP-dependent cell membrane transporter; it facilitates the efflux of xenobiotics from the cells to prevent damage for prolonged drug activity, including chemotherapeutics agents. In addition to MDR1, several reports in different cancers have indicated that the transcription factor Yin Yang 1 (YY1) is over-expressed and regulates tumor cell response to chemotherapeutic drugs. TESS analysis demonstrated that the gp170 proximal promoter contains four putative binding sites for the YY-1 protein. We also hypothesized that the YY1 may too be over-expressed in ALL and that its expression may be correlated with the expression of gp170. These hypotheses were examined first by reporter systems analyze, the gp170 protein was cloned and we developed a luciferase reporter assay. Examination of the putative YY1 binding sites that were individually mutated (deleted), showed revealed that mutation at the site –1860 abolished the activity. Mutation at the site –1920 abolished approximately 50% and mutation at –1230 site abolished approximately 25%. Further, CHIP analysis demonstrated that YY1 transcription factor binds directly to the gp170 gene MDR1 promoter. In addition, we examined the expression of YY1 and gp170 in childhood ALL (n= 84). The expression of YY1 and gp170 was determined evaluated by IHC in tumor tissues and the frequency of positive cells was determined. For comparison, normal controls were also analyzed (n=53). The findings demonstrate that were a significant increase in the frequency of positive cells in ALL compared to controls for both YY1 (38% vs. 8%, p=0.001) and for gp170 (42% vs. 12%, p=0.001). There was a good correlation between the expression of YY1 and gp170 (Pearson's test, r=0.4, p=0.001). The findings suggest that YY1 transcriptionally regulates the mdr1 and may be a therapeutic target in MDR positive ALL and its inhibition may reverse resistance to chemotherapeutic drugs.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4330. doi:1538-7445.AM2012-4330

Abstract 4582: Regulation of Krüppel-Like Factor 4 (KLF4) expressions via Yin Yang 1 (YY1) in B Non-Hodgkin's Lymphomas (B-NHLs): KLF4 upregulation is associated with unfavorable overall survival in pediatric B-NHL

Krüppel-like factor 4 (KLF4) is a transcription factor expressed in a variety of tissues in humans and has been implicated in several physiologic processes including development, differentiation, and tissue homeostasis. KLF4 is a bi-functional and can either activate or repress transcription depending on the target gene. For instance, KLF4 acts as a tumor suppressor gene (colon, gastric, esophageal, bladder, and NSCLC) or as an oncogene (laryngeal carcinoma, squamous cell carcinoma, ductal carcinoma of the breast). However, the role of KLF4 in hematological malignancies is still poorly understood. Studies in leukemia suggest that KLF4 may be a tumor suppressor. The goal of this study was to investigate the expression and the clinical significance of KLF4 in B cell non-Hodgkin's lymphomas (B-NHLs). Both B-NHL cell lines and patient-derived tumor tissues (TMA) were examined by western blot and immunohistochemistry (IHC), respectively. Using IHC, the expression of KLF4 was calculated based on the intensity and percentage of the area stained, and scoring was corroborated by two pathologists. The complete absence of KLF4 expression was considered as negative. A significant overexpression of KLF4 in Ramos and Raji (Burkitt's lymphoma) and 2F7 (AIDS lymphoma) B-NHL cell lines. However, the DHL4 (DBLCL) cell line showed a level of similar to that seen in normal cells. Among the 73 childhood lymphomas studied, 13/23 (57%) of lymphoblastic lymphoma, 7/20 (35%) of large B-cell lymphoma, 4/4 (100%) of anaplastic large cell lymphoma and 5/6 (83%) NHL not specified were KLF4 positive. Notably, 20/20 (100%) Burkitt's lymphoma were KLF4 positive. Nuclear expression of KLF4 was significantly higher in Burkitt's lymphoma (90%) compared to the remaining subtypes. The 3-year event-free survival rate (EFS) for the whole cohort was 67% (43% to 79%) compared to 23% (13% to 38%) in those who has tumors that were KLF4 positive, (p< 0.05). Multivariate analyses confirmed the association of KLF4 expression with unfavorable overall survival (OS; P<.005). Previous findings demonstrated overexpression of the transcription factor YY1 in B-NHL. In silico analysis of the KLF4 promoter identified the presence of four putative binding sites for YY1. We confirmed that –126 and –298 sites were binding sites for YY1 by ChIP analyses. The transcriptional regulation of KLF4 by YY1 was demonstrated following transfection with YY1 siRNA. We also found a positive correlation between the expression of YY1 and KLF4 in the NHL tissues, suggesting that YY1 regulates KLF4 in vivo. The present findings suggest that KLF4 may be considered as an oncogene in Burkitt's lymphoma, and in certain subsets of other types of lymphoma, and that KLF4 may be a potential prognostic factor. We propose that KLF4 may be a therapeutic target in patients with B-NHL.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4582. doi:1538-7445.AM2012-4582

Overexpression of Yin Yang 1 in the pathogenesis of human hematopoietic malignancies

The transcription factor Yin Yang (YY) 1 has been reported to be overexpressed in several tumor types and plays a role in both the progression of the disease as well as the maintenance of tumor cell resistance to cell death by cytotoxic drugs. YY1 also has been reported to be a prognostic factor for several cancers and was proposed to be a therapeutic target. The expression, function, and role of YY1 in the pathogenesis of hematologic malignancies are summarized briefly herein. Data are represented for B non-Hodgkin lymphoma, AIDS-related lymphoma, multiple myeloma, and children's acute lymphocytic leukemia.

Galiximab signals B-NHL cells and inhibits the activities of NF-κB-induced YY1- and snail-resistant factors: mechanism of sensitization to apoptosis by chemoimmunotherapeutic drugs

Galiximab (anti-CD80 monoclonal antibody) is a primatized (human IgG1 constant regions and cynomologus macaque variable regions) monoclonal antibody that is currently in clinical trials. Galiximab inhibits tumor cell proliferation through possibly cell signaling-mediated effects. Thus, we hypothesized that galiximab may signal the tumor cells and modify intracellular survival/antiapoptotic pathways such as the NF-κB pathway. This hypothesis was tested using various CD80(+) Burkitt B-NHL (non-Hodgkin lymphomas) cell lines as models. Treatment of B-NHL cells with galiximab (25-100 μg/mL) resulted in significant inhibition of NF-κB activity and its target resistant factors such as YY1, Snail, and Bcl-2/Bcl-XL. Treatment of B-NHL cells with galiximab sensitized the tumor cells to both cis-diamminedichloroplatinum(II) (CDDP)- and TRAIL-induced apoptosis. The important roles of YY1- and Snail-induced inhibition by galiximab in the sensitization to CCDP and TRAIL were corroborated following transfection of Raji cells with YY1 or Snail short interfering RNA. The transfected cells were shown to become sensitive to both CCDP- and TRAIL-induced apoptosis in the absence of galiximab. Furthermore, knockdown of YY1 or Snail inhibited Bcl-XL. The involvement of Bcl-XL inhibition in sensitization was corroborated by the use of the pan-Bcl-2 inhibitor 2MAM-3 whereby the treated cells were sensitive to both CDDP- and TRAIL-induced apoptosis. These findings show that galiximab inhibits the NF-κB/Snail/YY1/Bcl-XL circuit that regulates drug resistance in B-NHL and in combination with cytotoxic drugs results in apoptosis. The findings also support the therapeutic application of the combination of galiximab and cytotoxic drugs in the treatment of drug-resistant CD80-positive B-cell malignancies.

TUNEL-positive cells in the surgical border of an amputation due to infected diabetic foot

Diabetic infected foot is the outcome of progressive vascular and neurological damage caused by persistent chronic hyperglycemia. Due to acute hypoxia and infection, the tissues develop extensive necrosis and gangrene, which often require amputation. The decision regarding the level of amputation relies mainly on the personal experience of the surgeon who must identify the healthy tissue without necrosis. However, tissue cells under stress may succumb before clear evidence of necrosis is present. In this study, dying cells with DNA damage were identified in the necrotic lesions and surgical borders of amputations. Therefore, the main purpose of this study was to identify apoptosis in the surgical borders of amputations required to treat infected diabetic foot. Apoptosis was identified by terminal deoxynucleotidyl transferase-mediated bio-dUTP nick-end labeling (TUNEL) in the superficial and deep tissues of wounds, and in the surgical borders of 10 consecutive adult patients with diabetes mellitus type 2 (DM2) who underwent amputation due to infected diabetic foot. The severity of the disease was classified by the Acute Physiological and Chronic Health Evaluation II (APACHE II) score on admission, and laboratory data were collected and bacteriological cultures were obtained from the lesions. The ankle/arm blood pressure index was measured, the blood flow in the affected limb was evaluated by high-resolution ultrasonography and color Doppler and pulse oximetry were performed during surgery. A total of 5 males and 5 females, aged 45-84 years (58.8 ± 14.1), were included. The APACHE II score was 2-18 points (8 ± 5.7). A total of 9 patients developed sepsis and 2 succumbed. A total of 5 patients required above-ankle amputation, and 5 required toe disarticulation. The ankle/arm blood pressure index ranged from 0.23-0.85 (0.51 ± 0.23). Apoptotic cells were found in ulcers and abscesses, and in areas without necrosis. In the surgical borders of the amputations, apoptotic cells were found in skeletal muscle, blood vessels and peripheral nerves, particularly Schwann cells. Morphometric analysis revealed that the extent of apoptosis was 2-3 logarithms higher in the surgical borders of the infected diabetic foot compared to the venous ulcers, which were used as the reference. In conclusion, apoptosis was identified in regenerating tissues within diabetic foot wounds and in the surgical borders of amputations, where the surgeon considered the tissues to be undamaged. This information suggests that apoptosis may be present before visible signs of necrosis appear in the diabetic foot and may be caused by hypoxia, acidosis or proinflammatory cytokines. The extent of apoptosis in tissues proximal to necrotic areas may anticipate the development of diabetic foot and help the surgeon to make decisions regarding the need and extent of amputation.

Role of CXCL13 in asthma: novel therapeutic target

BACKGROUND

B cells play an important role in allergic asthma. However, the mechanisms by which these cells are activated in the airways remain poorly understood.

METHODS

We used a mouse model of ovalbumin (OVA)-induced allergic inflammation to study CXCL13 and to investigate the concentration of this chemokine in the BAL fluid derived from asthmatic and normal control subjects.

RESULTS

We found that OVA-challenged mice upregulate the CXCL13/CXCR5 axis, which is associated with several changes in their airways, including recruitment of B and CD4(+) cells, development of bronchial-associated lymphoid tissue, and airway inflammation. Treating sensitized mice with an anti-CXCL13 antibody reduced cell recruitment, bronchial-associated lymphoid tissue formation, and airways inflammation. Interestingly, measurements of CXCL13 using enzyme-linked immunosorbent assay showed that levels of this cytokine were significantly elevated in BAL fluid from subjects with asthma compared with control subjects (median, 162 [range, 120-296] vs 31 [range, 120-156] pg/mL; P = .005).

CONCLUSIONS

All together, these findings suggest that CXCL13 is involved in the allergic airway inflammatory process, and targeting this chemokine may constitute a novel approach in asthma.

Mcl-1 and YY1 inhibition and induction of DR5 by the BH3-mimetic Obatoclax (GX15-070) contribute in the sensitization of B-NHL cells to TRAIL apoptosis

The pan Bcl-2 family antagonist Obatoclax (GX15-070), currently in clinical trials, was shown to sensitize TRAIL-resistant tumors to TRAIL-mediated apoptosis via the release of Bak and Bim from Mcl-1 or Bcl-2/Bcl-XL complexes or by the activation of Bax, though other mechanisms were not examined. Herein, we hypothesize that Obatoclax-mediated sensitization to TRAIL apoptosis may also result from alterations of the apoptotic pathways. The TRAIL-resistant B-cell line Ramos was used as a model for investigation. Treatment of Ramos cells with Obatoclax significantly inhibited the expression of several members of the Bcl-2 family, dissociated Bak from Mcl-1 and inhibited the NFκB activity. Cells treated with Mcl-1 siRNA were sensitized to TRAIL apoptosis. We examined whether the sensitization of Ramos to TRAIL by Obatoclax resulted from signaling of the DR4 and/or DR5. Transfection with DR5 siRNA, but not with DR4 siRNA, sensitized the cells to apoptosis following treatment with Obatoclax and TRAIL. The signaling via DR5 correlated with Obatoclax-induced inhibition of the DR5 repressor Yin Yang 1 (YY1). Transfection with YY1 siRNA sensitized the cells to TRAIL apoptosis following treatment with Obatoclax and TRAIL. Overall, the present findings reveal a new mechanism of Obatoclax-induced sensitization to TRAIL apoptosis and the involvement of the inhibition of NFκB activity and downstream Mcl-1 and YY1 expressions and activities.

Hypoxia inducible factor promotes murine allergic airway inflammation and is increased in asthma and rhinitis

BACKGROUND

New therapies are necessary to address inadequate asthma control in many patients. This study sets out to investigate whether hypoxia-inducible factor (HIF) is essential for development of allergic airway inflammation (AAI) and therefore a potential novel target for asthma treatment.

METHODS

Mice conditionally knocked out for HIF-1β were examined for their ability to mount an allergic inflammatory response in the lung after intratracheal exposure to ovalbumin. The effects of treating wild-type mice with either ethyl-3,4-dihydroxybenzoate (EDHB) or 2-methoxyestradiol (2ME), which upregulate and downregulate HIF, respectively, were determined. HIF-1α levels were also measured in endobronchial biopsies and bronchial fluid of patients with asthma and nasal fluid of patients with rhinitis after challenge.

RESULTS

Deletion of HIF-1β resulted in diminished AAI and diminished production of ovalbumin-specific IgE and IgG(1) . EDHB enhanced the inflammatory response, which was muted upon simultaneous inhibition of vascular endothelial growth factor (VEGF). EDHB and 2ME antagonized each other with regard to their effects on airway inflammation and mucus production. The levels of HIF-1α and VEGF increased in lung tissue and bronchial fluid of patients with asthma and in the nasal fluid of patients with rhinitis after challenge.

CONCLUSIONS

Our results support the notion that HIF is directly involved in the development of AAI. Most importantly, we demonstrate for the first time that HIF-1α is increased after challenge in patients with asthma and rhinitis. Therefore, we propose that HIF may be a potential therapeutic target for asthma and possibly for other inflammatory diseases.

Expression of phosphorylated raf kinase inhibitor protein (pRKIP) is a predictor of lung cancer survival

Background

Raf-1 kinase inhibitor protein (RKIP) has been reported to negatively regulate signal kinases of major survival pathways. RKIP activity is modulated in part by phosphorylation on Serine 153 by protein kinase C, which leads to dissociation of RKIP from Raf-1. RKIP expression is low in many human cancers and represents an indicator of poor prognosis and/or induction of metastasis. The prognostic power has typically been based on total RKIP expression and has not considered the significance of phospho-RKIP.

Methods

The present study examined the expression levels of both RKIP and phospho-RKIP in human lung cancer tissue microarray proteomics technology.

Results

Total RKIP and phospho-RKIP expression levels were similar in normal and cancerous tissues. phospho-RKIP levels slightly decreased in metastatic lesions. However, the expression levels of phospho-RKIP, in contrast to total RKIP, displayed significant predictive power for outcome with normal expression of phospho-RKIP predicting a more favorable survival compared to lower levels (P = 0.0118); this was even more pronounced in more senior individuals and in those with early stage lung cancer.

Conclusions

This study examines for the first time, the expression profile of RKIP and phospho-RKIP in lung cancer. Significantly, we found that phospho-RKIP was a predictive indicator of survival.

Abstract 2162: Inhibition of the metastasis suppressor RKIP by EZH2 and YY1

The Raf kinase inhibitory protein (RKIP) acts as an activator of apoptosis and inhibitor of metastasis in prostate cancer. Diminished expression of RKIP has been reported in several cancers including prostate carcinomas; however, the underlying mechanism of RKIP regulation remains largely unknown. RKIP transcription is inhibited by the EMT inducer Snail which also represses the expression of the metastasis suppressor E-cadherin. E-cadherin and RKIP are co-expressed in many tumors. E-cadherin transcription is also suppressed by the polycomp repressive complex (PRP) transcription repressor, enhancer of zeste homolog 2 (EZH2), which mediates an H3 lysine 27 trimethylation in target promoters. EZH2 is highly expressed in several metastatic tumors including prostate cancer and its levels are inversely correlated with E-cadherin and RKIP expressions. The zinc-finger transcription factor Yin-Yang 1 (YY1) is also overexpressed in prostate tumors and has been associated with tumor progression. Silencing of YY1 by siRNA reverses the EMT phenotype of metastatic prostate cancer cell lines by induction of E-cadherin and RKIP. Here, we explored the direct roles of YY1 and EZH2 in the transcriptional regulation of RKIP in prostate cancer. We used as experimental models the metastatic and non-metastatic prostate cancer cell lines DU145 and LNCaP, respectively, which differ in the expression levels of EZH2, YY1 and RKIP. DU145 cells express low RKIP and high EZH2 and YY1 levels, whereas LNCaP cells express the opposite. Putative binding sites were identified for both YY1 and EZH2 (proximal E-boxes) within the RKIP promoter. CHiP analyses showed that both factors can physically associate with the RKIP promoter. Loss and gain of function reporter approaches showed that ectopic expression of EZH2 in LNCaP cells inhibits the wild type, but not the E-box mutant RKIP basal promoter activity. Similarly, a mutated EZH2 vector that lacks efficient binding to the target promoter couldn't inhibit the RKIP promoter activity. EZH2-mediated inhibition of RKIP promoter activity could also be inhibited by HDAC inhibitors, suggesting that HDAC recruitment and deacetylation of histone H3 is perquisite for EZH2 suppressive activity. Silencing of EZH2 or YY1 in DU145 also resulted in induction of RKIP promoter activity. The negative effect of YY1 on RKIP promoter activity was corroborated by inhibition of RKIP mRNA and protein levels. The above observations were further validated in prostate cancer tissue microarrays whereby YY1 and RKIP protein expressions were found to be inversely correlated. The present findings support the roles of EZH2 and YY1 as transcription repressors of RKIP in prostate cancer and suggest that their overexpression may be associated, in part, with the high cell metastatic potential through downregulation of RKIP. We propose that EZH2 and YY1 might be potential prognostic markers of prostate cancer progression and targets for therapeutic intervention.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2162. doi:10.1158/1538-7445.AM2011-2162

Abstract 3499: Identification of a novel mechanism by which the BH3 mimetic obatoclax sensitizes non-Hodgkin's lymphoma tumor cells to TRAIL-mediated apoptosis

The BH3 mimetic chemical antagonist obatoclax (GX15-070, Gemin X Pharmaceuticals) has been used in vitro and nowadays also in clinical trials for its potential therapeutic effects in both solid and lymph node malignancies. The effects of obatoclax treatment alone or in combination with cytotoxic drugs results in the reversal of tumor cell resistance. Studies by us and others have reported that inhibition of over expressed anti-apoptotic gene products such as Bcl-2 and Bcl-XL can reverse resistance to TRAIL. Obatoclax was shown to sensitize TRAIL-resistant solid tumors to TRAIL-apoptosis, inhibiting diverse anti-apoptotic molecules like Bcl-2, Bcl-XL and Mcl-1 through direct binding. We hypothesized that treatment of B-NHL cell lines with Obatoclax will result in tumor cell sensitization to TRAIL apoptosis by a different mechanism. B-NHL Ramos cell line were treated with different concentrations of Obatoclax (7-28 nM) and TRAIL (2.5-20 ng/ml) resulting in significant potentiation of apoptosis and synergy. Western analysis revealed that treatment with obatoclax resulted in significant inhibition of several members of the Bcl-2 family such as inhibition of Mcl-1, Bcl-XL, XIAP, and cIAP 1/2. In addition, obatoclax dissociated Bak from Mcl-1 as determined by immunoprecipitation. We found that, obatoclax inhibited the expression/activity of several members of the NF-κB pathway including phospho-p65, IKK2, and phosphor-IκB-α. The NF-κB activity inhibition by obatoclax was assessed by EMSA. We examined whether obatoclax-induced sensitization to TRAIL resulted from both signaling of DR4 and DR5. Treatment of Ramos cells with DR4 siRNA or DR5 siRNA and then treated with obatoclax and TRAIL resulted in the sensitization of cells treated with DR4 siRNA but not DR5 siRNA. We have previously reported that DR5 is negatively regulated by the transcription repressor YY1, upstream of NF-κB. We found that obatoclax inhibited YY1 transcription and expression. The direct role of YY1 inhibition by obatoclax in both DR5 upregulation and sensitization to TRAIL was determined in transfected cells with YY1 siRNA. Such cells showed upregulation of DR5 and sensitivity to TRAIL apoptosis. The inhibitory effect of obatoclax on Mcl-1 activity and the Mcl-1 direct role in sensitization was examined by treatment of cells with Mcl-1 siRNA. Such cells reversed their sensitivity to TRAIL-mediated apoptosis. Overall, the present findings reveal a new mechanism of obatoclax-induced sensitization to TRAIL by inhibiting NF-κB and downstream Mcl-1 and YY1. Both Mcl-1 and YY1 play a direct role in tumor cells sensitization to TRAIL mediated apoptosis. The present findings identify several new therapeutic targets modified by obatoclax whose modifications can reverse tumor cell resistance to TRAIL mediated apoptosis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3499. doi:10.1158/1538-7445.AM2011-3499

Unique Pattern of Overexpression of Raf-1 Kinase Inhibitory Protein in Its Inactivated Phosphorylated Form in Human Multiple Myeloma

Multiple myeloma (MM) is the second most common hematological and incurable malignancy of plasma cells with low proliferative activity in the bone marrow. MM patients initially respond to conventional therapy, however, many develop resistance and recurrences occur. We have identified RKIP as a novel gene product that is differentially overexpressed in MM cell lines and MM tissues compared to other studied tumors and normal bone marrow. This overexpression consisted, in large part, of a phosphorylated inactive form of RKIP at Ser153 (p-Ser153 RKIP). In contrast to RKIP, p-Ser153 RKIP lacks its ability to inhibit the MAPK signaling pathway. The overexpression of p-Ser153 RKIP in MM cell lines and MM tissues was further validated in a mouse model carrying a human MM xenograft, namely, LAGλ-1B. Bioinformatic analyses from databases support the presence of increased RKIP mRNA expression in MM compared to normal plasma cells. In these databases, high RKIP levels in MM are also correlated with the nonhyperdiploid status and the presence of IgH translocations, parameters that generally display more aggressive clinical features and shorter patients' survival irrespective of the treatment. Since RKIP expression regulates both the NF-κB and MAPK survival pathways, the overexpression of "inactive" p-Ser153 RKIP in MM might contribute positively to the overall cell survival/antiapoptotic phenotype and drug resistance of MM through the constitutive activation of survival pathways and downstream the transcription of anti-apoptotic gene products. The overexpression of RKIP and p-Ser153 RKIP in MM is the first demonstration in the literature, since in most tumor tissues the expression of RKIP is very low and the expression of p-Ser153 RKIP is much lower. The relationship between the levels of active RKIP and inactive p-Ser153 RKIP in MM may be of prognostic significance, and the regulation of RKIP activity may be a target for therapeutic intervention.

Mechanisms of nitric oxide-mediated inhibition of EMT in cancer: inhibition of the metastasis-inducer Snail and induction of the metastasis-suppressor RKIP

The role of nitric oxide (NO) in cancer has been controversial and is based on the levels of NO and the responsiveness of the tumor type. It remains unclear whether NO can inhibit the epithelial to mesenchymal transition (EMT) in cancer cells. EMT induction is mediated, in part, by the constitutive activation of the metastasis-inducer transcription factor, Snail and EMT can be inhibited by the metastasis-suppressor Raf-1 kinase inhibitor protein (RKIP) and E-cadherin. Snail is transcriptionally regulated by NF-κB and in turn, Snail represses RKIP transcription. Hence, we hypothesized that high levels of NO, that inhibit NF-κB activity, may also inhibit Snail and induce RKIP and leading to inhibition of EMT. We show that treatment of human prostate metastatic cell lines with the NO donor, DETANONOate, inhibits EMT and reverses both the mesenchymal phenotype and the cell invasive properties. Further, treatment with DETANONOate inhibits Snail expression and DNA-binding activity in parallel with the upregulation of RKIP and E-cadherin protein levels. The pivotal roles of Snail inhibition and RKIP induction in DETANONOate-mediated inhibition of EMT were corroborated by both Snail silencing by siRNA and by ectopic expression of RKIP. The in vitro findings were validated in vivo in mice bearing PC-3 xenografts and treated with DETANONOate. The present findings show, for the first time, the novel role of high subtoxic concentrations of NO in the inhibition of EMT. Thus, NO donors may exert therapeutic activities in the reversal of EMT and metastasis.

A potential mechanism of rituximab-induced inhibition of tumor growth through its sensitization to tumor necrosis factor-related apoptosis-inducing ligand-expressing host cytotoxic cells

Rituximab (anti-CD20 mAb) mediates antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and apoptosis in B-NHL cells. The contribution of other host-mediated cytotoxic effects has not been examined. The expression of death-inducing ligands (e.g. TRAIL) by host effector cells may contribute to the mechanism of tumor cell destruction in vivo by rituximab-mediated sensitization of resistant B-cell non-Hodgkin lymphoma (B-NHL) cells. We have examined the sensitizing activity of rituximab on B-NHL cell lines resistant to TRAIL (as model) and natural killer (NK)-induced apoptosis. Treatment of TRAIL-resistant B-NHL cell lines with rituximab sensitized the cells to TRAIL apoptosis and synergy was achieved via activation of the type II mitochondrial pathway for apoptosis. Further, rituximab (Fab')(2)-treated tumor cells were killed by purified peripheral blood-derived NK cells via TRAIL. Treatment of B-NHL cells with rituximab inhibited both YY1 DNA-binding activity and expression. Rituximab-mediated sensitization to TRAIL apoptosis was due, in large part, to rituximab-mediated inhibition of the transcription factor Yin Yang 1 (YY1). The direct role of YY1 in TRAIL sensitization by rituximab was shown in cells transfected with YY1 siRNA, and such cells mimicked rituximab and became sensitive to TRAIL-induced apoptosis. These data suggest that, in vivo, host effector cells expressing TRAIL may contribute to rituximab-mediated depletion of B-NHL cells.

Abstract 2290: A novel function in metastasis for YY1 overexpression in the initiation of the EMT phenotype

Metastasis is the main cause of death in cancer patients. The underlying molecular mechanisms of the metastatic process and their regulation in different malignancies are unknown. Survival pathways, such as the constitutively activated NF-κB pathway, contribute to the initiation of metastasis, a process known as epithelial to mesenchymal transition (EMT). The EMT phenotype is characterized by several gene modifications such as inhibition of epithelial gene products (e.g. E-cadherin, cytokeratin 18) and upregulation of mesenchymal gene products (e.g. vimentin and fibronectin). In addition, the cells exhibit invasive properties. The metastasis-inducer transcription factor, Snail, is intimately involved in EMT and is transcriptionally regulated, in part, by NF-κB. A recent report demonstrated that Snail is transcriptionally regulated, in part, by the transcription factor Yin Yang 1 (YY1) and YY1 is downstream of NF-κB. We have reported that YY1 expression is a prognostic marker in prostate cancer and YY1 also regulates tumor cell resistance to apoptosis by cytotoxic therapeutics. Based on these findings, we hypothesized that the expression levels of YY1 in cancer may also regulate EMT directly and/or indirectly through its regulation of Snail transcription. This hypothesis was tested using the human metastatic prostate carcinoma cell lines, PC-3 and DU-145, that exhibit the EMT phenotype as models. The relationship between inhibition of YY1 and inhibition of EMT was established by several lines of evidence. Treatment of the tumor cells with the proteasome inhibitors, NPI-0052 or Bortezomib, inhibited NF-κB, Snail and YY1 activities and correlated with inhibition of EMT. The direct role of YY1 expression and activity in the regulation of EMT was shown by treating cells with YY1 siRNA and resulting in the inhibition of the EMT phenotype. In turn, inhibition of Snail resulted in upregulation of the expression of the metastasis-suppressor/immune surveillance cancer gene product, Raf-1 kinase inhibitor protein (RKIP). The upregulation of RKIP by YY1 siRNA was due to the inhibition of the RKIP transcription repressor Snail. These findings establish a novel role for YY1 in the regulation of EMT. The findings also establish the dysregulation of the circuitry NF-κB/Snail/YY1/RKIP in cancer and metastasis resulting in the initiation of EMT. Further, this dysregulation has also been recently reported by us to regulate tumor cell resistance to apoptotic-inducing stimuli. Therefore, this dysregulated circuitry and downstream regulated gene products may be considered as novel targets for the regulation of both metastasis and resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2290.

Abstract 2422: The trimeric engineered fusion protein with CD154 peptide mimetic (OmpC-CD154p), induced apoptotic signaling in B-NHL cell lines mediated by caspase 3 and caspase 8 activation

CD154 (CD40-ligand) is a critical transmembrane molecule with potent immune-stimulatory properties and is clinical applied in gene therapy for leukemia and lymphoma. The interaction between CD40, a member of the tumor necrosis factor superfamily, and its ligand CD154 is essential for the development of humoral and cellular immune responses. Selective inhibition or activation of this pathway forms the basis for the development of new therapeutics against immunologically-based diseases and malignancies. Engagement of CD40-CD154 induces activation and proliferation of B lymphocytes and triggers apoptosis of carcinoma and B lymphoma cells. Several clinical trials have been reported targeting CD40 in cancer patients using recombinant CD154, mAbs and gene therapy, which were well tolerated and resulted in objective tumor responses. In addition to these therapies, CD154 mimetics have been considered with the objective to augment and potentiate the direct cytotoxic anti-tumor activity and for better accessibility to tumor sites. This approach was developed by us and we hypothesized that the genetic engineering of a fusion protein containing a CD154 peptide mimetic additional to be trimeric may be advantageous in that it may have a better affinity to CD40 on B cell malignancies and trigger cell death. The fusion partner may be a carrier targeting other surface molecules expressed on the malignant cells. This hypothesis was tested by the development of a gene fusion of Salmonella typhi OmpC protein expressing the CD154 Trp140-Ser149 amino acid strand. This OmpC-CD154p fusion protein binds CD40 and triggers the CD40 expressing B cells. In this study, we demonstrate that OmpC-CD154p treatment inhibits cell growth and proliferation, on B-NHL cell lines Raji and Ramos. In addition, significant apoptosis was achieved and the extent of apoptosis was a function of the concentration used and time of incubation. The anti-tumor effect was specific as treatment with OmpC alone had no effect. OmpC-CD154p treatment induced activation of caspase 3 active and caspase 8. These findings establish the basis for the development of new fusion proteins specificity targeting the tumor cells directly and mechanism mediated by extrinsic pathway.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2422.

Abstract 3374: BRAF and NRAS mutations in melanoma regulate the phosphorylation and inactivation of RKIP, the metastasis suppressor and immune surveillance cancer gene product

The Raf Kinase Inhibitor Protein (RKIP) is a member of the phosphatidylethanolamine binding protein family (PEBP). RKIP binds to Raf-1 and prevents the activation of the ERK 1/2 cascade. RKIP expression is diminished in many primary cancers and is absent in many metastases. RKIP overexpression inhibits experimental metastases, hence, termed a metastasis suppressor. In addition, overexpression of RKIP reverses tumor cell resistance to drug-induced apoptosis, hence, termed an immune surveillance cancer gene product. Phosphorylation of RKIP (pRKIP) at Ser 153 by PKCs dissociates RKIP from Raf-1 (inactivating RKIP) and pRKIP binds to G-protein coupled receptor kinase 2 (GRK2, a kinase that inhibits G-protein coupled receptors (GPCRs) and resulting in the inhibition of GRK2 activity and stimulation of the ERK 1/2 activity. Over 90% of melanoma express oncogene mutations in BRAF and also express mutations in NRAS. Most of the transforming activity of these mutations results from the activation of MAPK. The roles of such mutations in the regulation of oncogenes involved in metastasis and resistance are not clear. The objective of this study was to initiate investigations on the roles of above mutations on the expression of RKIP and inactive pRKIP. We hypothesized that BRAF and NRAS mutations, through their activation of PKCs, will result in the phosphorylation and inactivation of RKIP and potentiation of ERK 1/2 activation, metastasis and drug resistance. In this study, we have examined a large panel of melanoma cell lines with no mutations and with BRAF and/or NRAS mutations using a Tissue microarray technology. The expression of both RKIP and pRKIP was examined and the evaluation of protein expression was performed by IHC and analyzed by blinded observers under light microscopy. While anti-RKIP antibody detects both RKIP and pRKIP, anti-pRKIP was specific for pRKIP. The mean intensities for the expression of each protein were determined using the software Image-ProPlus 6.3. In brief, five random fields of each cell line were evaluated at 400-magnification. From the IHC staining, general density expressions of each protein in the cell lines were measured in pixels/200 μm2. The data revealed that the majority (75%) of RKIP expression was in its phosphorylated form in cell lines with BRAF and NRAS mutations. These studies suggest that in melanoma cell lines with mutations, GRK2 is inactivated through its association with pRKIP and, thus, maintaining the activating signals mediated by GPCRs. Further, pRKIP expression may potentiate the metastatic potential and drug resistance. We propose that selective inhibitors of PKCs may elevate the expression of RKIP and result in the inhibition of the metastatic potential as well as in the sensitization of the tumor cells to subtoxic therapeutic drugs. These studies are currently being examined in our laboratories.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3374.

Abstract 806: Upregulation of Krüppel-like Factor 4 (KLF-4) expression as a potential tumor progression gene product in non-Hodgkin's lymphoma

Krüppel-like factor 4 (KLF-4) is highly expressed in epithelial tissues such as gut and skin. Several studies based on clinical evidence suggest that KLF-4 functions as a tumor suppressor in cancer of colon, bladder, stomach and in leukemia. In contrast, KLF-4 expression is increased in primary breast ductal carcinomas and in oral dermal squamous cell carcinomas, suggesting that KLF-4 is important in tumor development and progression. However, KLF-4 expression in lymphomas has not been investigated. Our preliminary studies have examined KLF-4 expression in lymphoma cell lines and a TMA containing fresh tissues derived from patients with several types of lymphoma. There was a significant higher expression of KLF-4 in Burkitt's lymphoma compared with other lymphomas such as follicular or DLBCL. These findings suggest that KLF-4 may be considered as a new biomarker in Non-Hodgkin's lymphoma (NHL). Further analyses based on the clinical outcome revealed that KLF-4 protein expression was significantly associated with poor patient's survival. The increased KLF-4 expression was associated with an inferior survival duration (P= 0.002). The survival for 12 patients who had a tumor with weak KLF-4 expression and 13 patients with negative KLF-4 expression was significantly longer than the 30 patients with strong KLF-4 expression (P< 0.001). Other variables that affected survival in univariate analyses included stages and completeness of resection were shown to have statistically significant effect on survival (P=0.001), however age or sex did not have a statistically significant effect on survival. These data provide the first clinical and causal evidences that alterations of KLF-4 expression can play a critical role in the development and progression of NHL.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 806.

Abstract 664: Galiximab (anti-CD80 mAb) sensitizes TRAIL-resistant B-lymphoma to TRAIL-induced apoptosis via inhibition of the transcription repressor Yin Yang 1 (YY1)

Treatment of B-lymphomas with rituximab, alone or in combination with chemotherapy, resulted in significant clinical responses and prolongation of survival. However, a significant subset relapses or does not respond to initial treatments. Therefore, there is an urgent need to identify new targets and develop therapies to reverse resistance. CD80 is expressed on APCs and normal B cells and most B-lymphomas express CD80 on the surface. A primatized anti-CD80 mAb, galiximab, was developed and shown to inhibit tumor cell proliferation and mediates ADCC. A phase I/II clinical study with galiximab in patients with refractory B lymphomas demonstrated its safety TRAIL is a death-inducing ligand that is not toxic to normal cells but selectively cytotoxic to sensitive tumor cells and is currently in clinical trails in patients with a variety of cancers. The objective of this study was to investigate whether galiximab can sensitize TRAIL-resistant B lymphoma to TRAIL-induced apoptosis. We hypothesized that galiximab-induced inhibition of cell proliferation must have triggered the cells and inhibited constitutively activated survival pathways, such as NF-κB, and downstream anti-apoptotic gene products, thus, reducing the threshold of resistance and facilitating TRAIL to mediate apoptosis. This hypothesis was tested in vitro using CD80+ Raji cells as model and recombinant TRAIL. Galiximab was obtained from Biogen Idec. Treatment of Raji with galiximab (5-40 μg/ml) for 18h and followed by treatment with TRAIL (2.5-10 ng/ml) resulted in significant apoptosis as assessed by activation of Caspase 3. Galiximab treatment of Raji inhibited the NF-κB pathway and its DNA-binding activity as assessed by western and EMSA, respectively. The direct role of NF-κB-induced inhibition by galiximab in sensitization was corroborated by the use of the NF-κB inhibitor DHMEQ. We have reported that the TRAIL receptor DR5 transcription repressor YY1 regulates tumor-cell sensitivity to TRAIL. We have found that galiximab inhibits YY1 expression and DNA-binding activity in Raji in parallel with upregulation of DR5. The direct role of YY1-induced inhibition by galiximab in TRAIL sensitization was corroborated in cells transfected with siRNA YY1 and which were sensitive to TRAIL apoptosis. Sensitization by galiximab was due, in part; to activation of the type II mitochondrial pathway for apoptosis. Galiximab-induced inhibition of anti-apoptotic Bcl-2 family, such as Bcl-2 and Bcl-XL, in sensitization was verified by the use of the specific Bcl-2 inhibitor, 2 MAM-A3. Altogether, these findings established that galiximab is capable to sensitize TRAIL-resistant B lymphomas to TRAIL apoptosis. The findings also suggest the potential therapeutic application of the combination of galiximab and TRAIL or agonist DR4/DR5 antibodies in the treatment of resistant B lymphomas.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 664.

Abstract 2242: Correlation between the overexpression of the metastasis-inducer transcription factors Snail and Yin Yang 1 and BRAF mutations in a large panel of melanoma cell lines

Over 90% of melanoma express oncogenic mutations in BRAF at the V600E position. Most of the transforming activity of the BRAF V600E is thought to result through the activation of the mitogen-activated protein kinase (MAPK) pathway. The discovery of BRAF mutations has alluded to targeted therapy. The role of BRAF mutations in the regulation of oncogenes involved in metastasis has not been fully explored. The metastasis-inducer gene product Snail regulates the EMT phenotype in the metastasis cascade. Snail is under the transcription regulation of NF-κB and is constitutively activated in tumors. Noteworthy, Snail negatively regulates the expression of the metastasis suppressor gene product, RKIP. Likewise, Yin-Yang 1 (YY1) regulates Snail and is downstream of NF-κB. The regulation of the YY1, Snail and RKIP expressions by BRAF mutations has been investigated. We hypothesized that the expression levels of YY1 will be correlated with the expression levels of Snail and inversely correlated with the expression levels of RKIP in melanoma and that the BRAF mutations may enhance these relationships due to its activation of the NF-κB pathway. In this study, we have analyzed a panel of 32 melanoma cell lines with BRAF mutations using a tissue microarray technology. The gene products YY1, Snail and RKIP were examined and, in addition, the inactive phosphorylated form of RKIP was also evaluated. Protein expressions were assessed by immunohistochemistry and were then analyzed by blinded observers under light microscopy. The mean intensities for the expression of each gene product were determined by using the software Image-ProPlus 6.3. The data revealed the following: (1) There was a correlation between the levels of YY1 and Snail expressions in the cell lines and (2) There was an inverse correlation between the levels of RKIP and both Snail and YY1 levels. The relationship between active RKIP and inactive phospho-RKIP demonstrated that the majority was in the inactivated phosphorylated form. These findings demonstrate that melanoma with BRAF mutations, which activate the NF-κB pathway, resulted in the upregulation of the metastasis inducer gene products YY1 and Snail and, consequently, inhibition and/or inactivation of the metastasis-suppressor RKIP. Thus, these studies revealed that BRAF mutations regulate the EMT metastatic phenotype through the activation of NF-κB, Snail, and YY1, while inhibiting and/or inhibiting the metastasis suppressor RKIP. We suggest that Snail, YY1, and RKIP are potential targets for therapeutic intervention in the inhibition of metastasis. In addition, we have shown that these same gene products regulate tumor cell resistance to cytotoxic therapeutics and, thereby, targeted therapeutic interventions may exert dual roles in the inhibition of metastasis and reversal of resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2242.

Abstract 1466: The NO donor DETANONOate inhibits the EMT phenotype in human metastatic prostate carcinoma cell lines: pivotal roles of inhibition of NF-κB and Snail activities and induction of RKIP

Nitric oxide (NO) has been shown to mediate contrasting effects on tumorigenesis i.e. at low levels NO is pro-tumorigenic and at high levels NO is anti-tumorigenic. Recent studies revealed that treatment of tumor cell lines with NO donors at high levels significantly inhibited cell growth and survival pathways such as the constitutively activated NF-κB. Tumor cells with activated NF-κB were reported to have the capacity to initiate the metastatic cascade via induction of epithelial to mesenchymal transition (EMT). The EMT phenotype is characterized by decreased expression of epithelial gene products (e.g. E-cadherin, cytokeratin 18) and upregulation of mesenchymal gene products (e.g. vimentin, fibronectin). In addition, the tumor cells exhibit invasive and migratory properties. Based on these above findings, we hypothesized that treatment of metastatic prostate carcinoma cell lines, PC-3 and DU-145 with DETANONOate (500-1000μM) may reverse the EMT phenotype. This hypothesis was tested and treatment of the cells with DETANONOate resulted in inhibition of the EMT phenotype through inhibition of NF-κB activity. Inhibition of NF-κB was shown to be due, in part, to S-nitrosylation of p50. In addition to the inhibition of EMT phenotype, treatment with DETANONOate also inhibited invasive properties. The dual roles of DETANONOate-mediated inhibition of NF-κB and EMT were corroborated by the use of the NF-κB inhibitor DHMEQ. We examined the underlying mechanism by which NF-κB-induced inhibition by DETANONOate resulted in the inhibition of EMT. The EMT-induced transcription factor Snail was highly expressed in PC-3 and DU-145 cells. Treatment with DETANONOate inhibited Snail expression concomitant with inhibition of EMT. The direct role of Snail inhibition by DETANONOate and the inhibition of EMT was corroborated in cells transfected with Snail siRNA and such treatment reversed the EMT phenotype, mimicking DETANONOate. Inhibition of the repressor activity of Snail by DETANONOate resulted in the upregulation of the Raf-1 kinase inhibitory protein (RKIP). The role of RKIP induction in the reversal of EMT was corroborated in cells overexpressing RKIP. The in vitro findings with DETANONOate-induced inhibition of EMT were validated in mice bearing PC-3 xenografts. Treatment with DETANONOate and analysis by IHC of tumor biopsies revealed that the EMT phenotype was reversed. There was an inverse correlation between Snail inhibition and RKIP induction. The present findings demonstrate, for the first time, that NO donors (high concentrations) inhibit the EMT phenotype and suggest their potential therapeutic applications in vivo in patients. These studies also suggest that the NF-κB/Snail/RKIP circuitry is dysregulated in tumor cells and is responsible, in part, for the EMT phenotype.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1466.

Aryl hydrocarbon nuclear translocator (hypoxia inducible factor 1beta) activity is required more during early than late tumor growth

c4 is a derivative of the mouse hepatoma cell line, Hepa-1, that harbors a mutation in the aryl hydrocarbon receptor nuclear translocator gene (Arnt, or hypoxia inducible factor 1beta [HIF-1beta]) leading to loss of activity. Clone 3 cells were generated by introducing a doxycycline-repressible Arnt expression vector into c4 cells. Clone 3 cells were injected subcutaneously into immunosuppressed mice, which were treated with doxycyline (a) throughout the growth of the subsequent tumor xenografts, or (b) from day 7 through to the end of the experiment (day 30), or not treated (c). Tumors in all groups grew exponentially between days 14 and 30, and at rates that were indistinguishable from each other. However, tumors in group a were smaller than those of the other two groups throughout the measurable growth period, while tumor volumes in groups b and c were not significantly different from each other. The degrees of vascularity and apoptosis did not correlate with the differences in degrees of growth between the different groups. Thus, Arnt is required during the early stages of growth of the tumors but less in later stages. Since Arnt does not detectably effect the growth kinetics of Hepa-1 cells either during hypoxia or normoxia, this requirement is unlikely to reflect a direct effect of Arnt on cell proliferation, and is therefore probably a consequence of altered interaction(s) between the tumor cells and the host. These studies suggest that Arnt (and HIF-1alpha/HIF-2alpha) inhibitors will be particularly effective against smaller tumors, including micrometastases.

Rituximab-mediated cell signaling and chemo/immuno-sensitization of drug-resistant B-NHL is independent of its Fc functions

PURPOSE

Rituximab [chimeric anti-CD20 monoclonal antibody], alone or combined with chemotherapy, is used in the treatment of non-Hodgkin's lymphoma (NHL). Rituximab binds to CD20 and inhibits intracellular survival/growth pathways leading to chemo/immunosensitization of tumor cells in vitro. The contribution of rituximab Fc-FcR interaction in signaling is not known. This study examined the role of Fc-FcR interactions in rituximab-induced signaling using rituximab (Fab')(2) fragments as well as rituximab devoid of the CH2 Fc-binding domain (CH2(-)).

EXPERIMENTAL DESIGN

Rituximab (CH2(-)) and rituximab (Fab')(2) were tested for their activity on B-NHL cell lines. Cell signaling and sensitization to chemotherapy and immunotherapy were examined. The in vitro studies were validated in mice bearing tumor xenografts.

RESULTS

Although the modified antibodies were defective in antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity functions, they retained all other biological activities such as inhibition of cell proliferation, induction of cell aggregation, and apoptosis induction. In addition, similar to rituximab, the modified antibodies inhibited the activity of cell survival/growth pathways and their associated transcription factors (e.g., NF-kappaB, YY1, SP-1), and signal transducers and activators of transcription 3 (STAT-3), and downregulated the expression of antiapoptotic gene products, such as Bcl-2/Bcl(xl), which regulate drug resistance. The modified antibodies, similar to rituximab, sensitized resistant B-NHL cells to both CDDP and Fas ligand-induced apoptosis. Furthermore, treatment of nude mice bearing Raji tumor cell xenografts with the combination of rituximab (Fab')(2) or rituximab and CDDP resulted in similar and significant inhibition of tumor growth.

CONCLUSION

These findings reveal that rituximab-mediated inhibition of intracellular signaling pathways and leading to chemo/immuno-sensitization of resistant B-NHL is Fc independent.

The aryl hydrocarbon receptor nuclear translocator (Arnt) is required for tumor initiation by benzo[a]pyrene

Benzo[a]pyrene (B[a]P) is a ligand for the aryl hydrocarbon receptor (Ahr). After binding ligand, Ahr dimerizes with the aryl hydrocarbon receptor nuclear translocator (Arnt) protein, and the dimer upregulates the transcription of Cyp1a1, Cyp1b1 and other enzymes involved in the metabolic activation of B[a]P. Arnt null mice die in utero. Mice in which Arnt deletion occurs constitutively in the epidermis die perinatally. In the current study, mice were developed in which the Arnt gene could be deleted specifically in adult skin epidermis. This deletion had no overt pathological effect. Homozygosity for a null reduced nicotinamide adenine dinucleotide (phosphate): quinone oxidoreductase allele was introduced into the above mouse strain to render it more susceptible to tumor initiation by B[a]P. Deletion of Arnt in the epidermis of this strain completely prevented the induction of skin tumors in a tumor initiation-promotion protocol in which a single topical application of B[a]P acted as the tumor-initiating event, and tumor promotion was provided by repeated topical applications of 12-O-tetradecanoyl phorbol-13-acetate (TPA). In contrast, deletion of Arnt did not prevent the induction of skin tumors in a protocol also using TPA as the promoter but using as the initiator N-methyl-N'-nitro-N-nitrosoguanidine, whose activity is unlikely to be affected by the activity of Ahr, Arnt or their target genes. These observations demonstrate that Arnt is required for tumor initiation by B[a]P in this system.

Can we develop biomarkers that predict response of cancer patients to immunotherapy?

PRIMARY OBJECTIVE

The primary objective is to delineate the potential utility of cancer biomarkers that correlate and predict response to immunotherapy in cancer patients who are refractory to conventional therapeutics. Unlike significant development of biomarkers that predict response to chemotherapy, very few biomarkers have been developed to predict the response to immunotherapy.

MAIN OUTCOMES AND RESULTS

This article describes briefly the importance of characterizing and validating biomarkers for immunotherapy. A few examples have been provided, such as the transcription factor NF-kappaB, the transcription repressor Yin-Yang 1 (YY1), the pro-apoptotic gene product (Smac/DIABLO) and the circulating Fas and Fas ligand. These biomarkers have been determined to be of prognostic significance in different cancers.

CONCLUSIONS

Immunotherapy is considered as an alternative therapy in the treatment of cancer patients who are refractory to chemotherapy/radiation/hormonal therapies. Cross-resistance to apoptosis develops between cancer cells that are resistant to conventional therapeutics and immunotherapy. Therefore, it is important to develop biomarkers that will determine patient response to immunotherapy.

2-Methoxyestradiol (2-ME) reduces the airway inflammation and remodeling in an experimental mouse model

Patients with asthma experience airway structural changes, termed airway remodeling, in response to persistent inflammation. 2-Methoxyestradiol (2-ME) is an anti-angiogenic agent and downregulates hypoxia-inducible factor 1 (HIF-1) and inhibits HIF-1alpha-induced transcriptional activation of vascular endothelial growth factor (VEGF) expression. We hypothesized that 2-ME may interfere with the development of the clinical manifestations of asthma. We used a chronic murine model of allergic airway inflammation with subepithelial fibrosis in BALB/c mice. Mice were sensitized with ovalbumin (OVA) that was administered intraperitoneally at days 0-5 and challenged intratracheally (IT) with OVA on days 12-22. The mice received 2-ME IT at days 24, 26 and 28 and sacrificed at day 32. The sensitized/challenged mice developed an extensive cell inflammatory response of the airways. 2-ME administration significantly reduced the cellular infiltrate in the perivascular and peribronchial lung tissues, reduced goblet mucous production, reduced airway fibrosis and thickness of smooth muscle and blood vessels, and reduced eosinophil infiltration. Mice treated with 2-ME had a significant decrease of HIF-1 and VEGF expression in the perivascular, peribronchial, and interstitium of lung tissues. Collagen IV expression was also significantly reduced in 2-ME treated mice compared to untreated mice. The 2-ME treatment was associated with a significant decrease of OVA-specific IgE antibodies. These findings provide the first indication that IT administration of 2-ME is effective in preventing and reversing antigen-induced airway remodeling in the OVA allergen inflammatory murine model. The potential role of 2-ME in patients is discussed.

Novel therapeutic applications of nitric oxide donors in cancer: roles in chemo- and immunosensitization to apoptosis and inhibition of metastases

The treatment of primary tumors results in an initial response to approved conventional therapeutics. However, recurrences and malignancies develop as a result of tumors' acquisition of anti-apoptotic mechanisms of resistance. Hence, there is an urgent need of novel therapeutics that can reverse resistance. One approach of interest is the inhibition of cell survival and anti-apoptotic pathways by sensitizing agents that can render resistant tumor cells sensitive to respond to various cytotoxic therapies. We have found that nitric oxide donors, similar to DETANONOate, inhibit cell survival anti-apoptotic pathways, such as the constitutively activated NF-kappaB and sensitize drug-resistant tumor cells to apoptosis by both chemotherapy and immunotherapy. Sensitization by DETANONOate was shown to inhibit the transcription repressor Yin Yang1 (YY1) shown to regulate resistance to both Fas ligand and TRAIL. In addition, DETANONOate-induced inhibition of NF-kappaB results downstream in the inhibition of several anti-apoptotic gene products, thus facilitating the activation of the apoptotic pathways with both chemotherapy and immunotherapy. In addition, DETANONOate induces the expression of the metastatic tumor suppressor gene product, Raf-1 Kinase Inhibitor Protein (RKIP), which inhibits the survival pathways induced by NF-kappaB and Raf-1/MEK which also contributes to the sensitizing activity. This indicates a novel finding that RKIP may also play an important role in the prevention of metastasis. Inhibition of NF-kappaB activation by DETANONOate results downstream in the inhibition of the RKIP transcription repressor Snail, resulting in upregulation of RKIP. Inhibition of Snail results in downstream inhibition of the metastatic cascade initiated by the epithelial-mesenchymal transition (EMT). Thus, nitric oxide donors have the dual functions of both sensitizing tumor cells to chemotherapy and immunotherapy and are also involved in the regulation and inhibition of metastasis.

CDIP-2, a synthetic peptide derived from chemokine (C-C motif) ligand 13 (CCL13), ameliorates allergic airway inflammation

Airway inflammation is characterized by selective recruitment of mononuclear and granulocytic cells. This recruitment is mediated by the action of chemotactic cytokines, such as chemokines. A number of chemokines and their receptors have been identified and proposed as potential therapeutic agents in allergic airway inflammation. One of these chemokines is chemokine (C-C motif) ligand 13 (CCL13), a CC chemokine that has been associated with allergic inflammatory diseases such as asthma and allergic rhinitis. To investigate alternative therapeutic agents to alleviate allergic inflammatory diseases, a number of chemokine-derived synthetic peptides were designed and tested for their ability to modulate in vitro and in vivo chemokine-mediated functions. Our results show that one of these peptides, CDIP-2, displayed antagonist functions in in vitro chemotaxis assays using monocytic cell lines. In addition, we found that CDIP-2 significantly reduced peribronchial, perivascular infiltrate and mucus overproduction in an ovalbumin-induced allergic lung inflammation murine model. Thus, CDIP-2 may be considered as part of a novel group of anti-inflammatory agents based on chemokine-derived synthetic peptides.

The NO TRAIL to YES TRAIL in cancer therapy (review)

Treatment of cancer patients with conventional therapies (chemotherapy, hormonal therapy, immunotherapy and radiation) respond initially well and experience prolonged tumor-free survival. However, in many patients tumor recurrences and relapses occur and such tumors exhibit the resistant phenotype i.e. cross-resistance to various cytotoxic and apoptotic agents. Therefore, new therapeutic strategies are currently being explored and are based on a better understanding of the underlying biochemical and molecular mechanisms of tumor cell resistance. Hence, novel sensitizing agents that can modify the tumor dysregulated apoptotic gene products can reverse resistance when used in combination with subtoxic doses of cytotoxic reagents. Targeted anti-tumor therapies are the current choice in the treatment of resistant tumors. One such targeted therapy is the application of TRAIL or TRAIL agonist monoclonal antibodies (mAbs) (anti-DR4 and anti-DR5) because, unlike Fas ligand and TNF-alpha, they are not cytotoxic to normal tissues. TRAIL as monotherapy will only be effective against TRAIL sensitive tumors, however, most tumors are resistant to TRAIL and their sensitization can restore their sensitivity to TRAIL apoptosis. We present, herein, one potential novel sensitizing agent, namely, nitric oxide (NO) that has been shown to sensitize TRAIL-resistant tumor cells to TRAIL apoptosis via its inhibitory effect on the transcription factors NF-kappaB and Yin Yang 1 (YY1), concomitantly with upregulation of DR5. We propose the therapeutic application of NO donors as sensitizing agents used in combination with TRAIL/DR4 or DR5 mAbs in the treatment of TRAIL-resistant tumors.

Modification of Gene Products Involved in Resistance to Apoptosis in Metastatic Colon Cancer Cells: Roles of Fas, Apaf-1, NFκB, IAPs, Smac/DIABLO, and AIF

BACKGROUND

Colon cancer becomes resistant to apoptosis as it acquires metastatic potential. SW480 and SW620 colon cancer cells were established from the same patient at different stages of tumor progression. The stage III colorectal cancer cell line (SW620) is more resistant to apoptosis. In the present report, we investigated the apoptotic gene products that might account for colon cancer evasion of immune attack and chemoradioresistance-induced apoptosis.

METHODS

SW480 and SW620 cells were used for this experiment. Type 1 apoptosis was induced by CH-11. Type 2 apoptosis was induced by cisplatin and ionizing radiation. Apoptosis was determined by caspase-3 activity and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling. Gene products Fas, TRAIL, c-FLIP, Bid, BAX, Bcl-2, Bcl-xL, Apaf-1, nuclear factor-kappa B, Smac/DIABLO, apoptosis inducing factor, and the inhibitors of apoptosis were investigated by immunocytochemistry and Western blot analyses.

RESULTS

SW620 cell lines were more resistant to both Type 1 and Type 2 apoptosis induced by CH-11, cisplatin, and ionizing radiation, respectively. Examination of the extrinsic pathway demonstrated Fas receptor to be down-regulated in SW620. Apaf-1 was decreased in SW620 cells; while other members of the mitochondrial pathway including Bax, Bid, Bcl-xL, and Bcl-2 demonstrated minimal alterations of protein levels in both cell lines. Survivin and XIAP protein levels were increased in SW620 cells, which correlated with nuclear expression of nuclear factor-kappa B in SW620 cells but not SW480. Mitochondrial-released factors including Smac/DIABLO and apoptosis inducing factor were increased in SW480 cells.

CONCLUSIONS

SW620 cells have acquired genetic defects both in the intrinsic and extrinsic pathways of apoptosis, which may explain in part the ability of colon cancer cells to escape the immune system and to become chemoradioresistant. These genes may be potential targets for chemoradiosensitization in advanced colorectal cancer.

Identification of potential B cell epitope determinants by computer techniques, in hemagglutinin-neuraminidase from the porcine rubulavirus La Piedad Michoacan

Hemagglutinin-neuraminidase (HN) from porcine rubulavirus La Piedad Michoacan (RvpLPM) is one of the most antigenic proteins known, and is responsible for virus-host cell interaction. We analyzed the amino acid sequence of HN, using computer-assisted techniques to identify B cell epitopes. From a pool of 18 possible antigenic peptides, we evaluated the antigenicity of the 2 peptides with the highest scores and the 1 with lowest score. Antibodies from RvpLPM-infected pigs recognized the synthesized HN-A, HN-B, and HN-R peptides (optical density [OD]: 0.33 +/- 0.02 for HN-A, 0.20 +/- 0.02 for HN-B, and 0.07 +/- 0.01 for HN-R); bovine serum albumin-coupled HN-A and HN-B induced rabbit anti-RvpLPM antibodies (OD: 0.39 +/- 0.01 for HN-A and 0.35 +/- 0.02 for HN-B). Loop 5 from the outer membrane protein, OmpC, from Salmonella typhi was replaced with HN-B; this protein was then expressed in Escherichia coli UH302. BALB/c mice were challenged intraperitoneally or orogastrically with the fusion protein expressed in E. coli and murine antibodies obtained from both types of administration inhibited virus-hemagglutinating activity, as did the antibodies from RvpLPM-infected swine. These results suggest that HN-A and HN-B are peptides involved in RvpLPM cell carbohydrate recognition, and could therefore be considered potential targets for vaccine and diagnostic procedures development.

Overexpression of VEGF and TGF-beta1 mRNA in Pap smears correlates with progression of cervical intraepithelial neoplasia to cancer: implication of YY1 in cervical tumorigenesis and HPV infection

The screening of neo-angiogenesis related gene expression has uncovered many disrupted molecular pathways which may significantly confer to malignant transformation of various cell types including cervical cells. The objective of the present study was to delineate whether changes in certain gene expression profiles during the malignant conversion of the uterine cervix can be potentially used to predict the clinical course and outcome of the cervical pathology. Total RNA was isolated from Pap smears obtained from healthy females or patients diagnosed with low-grade squamous cervical intraepithelial lesions (LG-SIL), high-grade (HG)-SIL or cervical carcinoma. VEGF, TGF-beta1 and YY1 mRNA expression levels were assessed by QRT-PCR. Confirmation of YY1 protein discrepancy among cervical tissues of different histopathology was performed by immunohistochemistry. All tested genes showed statistically significant expression variations among the indicated groups. VEGF and TGF-beta1 mRNA overexpression was found to be associated with progression from low-grade to high-grade cervical intraepithelial neoplasia (CIN), while YY1 showed constitutively elevated transcript levels in CIN and cervical cancer compared to controls. At the protein level YY1 was also overexpressed in HG-SIL and cancer tissues compared to LG-SIL. Both YY1 transcript and protein overexpression were associated with HPV18- or HPV16-infected samples. Spearman analysis revealed a co-expression pattern for VEGF and TGF-beta1 mRNAs in normal cervix and LG-SIL; however, YY1 expression correlated negatively with VEGF and TGF-beta1 transcript levels upon the onset of the cervical neoplastic transformation. Our findings provide for the first time evidence for the implication of YY1 in uterine cervix carcinogenesis and suggest that VEGF, TGF-beta1 and YY1 could be useful biomarkers of cervical malignant transformation as well as potential targets for therapeutic approaches.

Apoptosis inducing factor is decreased in metastatic colon cancer in ex-vivo models of colon carcinogenesis by tissue microarray

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Background: In vitro studies suggest that apoptosis inducing factor (AIF) expression is decreased in metastatic cells relative to those derived from primary tumors. This study was undertaken to determine AIF expression patterns in patients with stage I/II vs. stage III/IV colorectal cancers. Methods: Colon cancer specimens were prospectively collected (11/05–6/06) from 12 patients from 3 different sites: tumor, adjacent to tumor, and tissue 2 cm from the tumor. Paraffin-embedded specimens were examined by tissue microarray with AIF-specific antibodies. Total AIF expression as well as cytoplasmic and nuclear expression was assessed by an investigator blinded to the tissue site and patient stage. Staining was assessed as: 1=absent, 2=mild, 3=moderate, 4=high and 5=very high. The clinical characteristics and tumor stage of all patients were analyzed. Results: All patients were male. Eight patients had non-metastatic disease at the time of laparotomy, four had metastasis to: lymph nodes (n=3) and liver (n=1). Stage I/II patients (n=8) were of similar age compared to stage III/IV patients (n=4) [61.3±4.2 vs. 54.4±6.0 y.o.; p=0.6] had similar tumor size (3.81±0.7 vs. 4.08±1.4 cm; p=0.4). There was no difference in the level of expression of AIF in normal tissue collected 2-cm away from the tumor site in stage I/II vs. stage III/IV colon cancers in the cytoplasm (3.81±0.17 vs. 3.30±0.38; p=0.4), nucleus (3.19±0.43 vs. 2.49±0.46; p=0.8) or overall (4.06±0.27 vs. 3.37±0.8). A significant decrease in AIF expression was observed in stage III/IV tumors compared to stage I/II tumors in tissue collected adjacent to the tumor in the cytoplasm (3.12±0.22 vs. 4.46±0.25; p=0.03), the nucleus (2.10±0.44 vs. 3.63±0.32; p=0.03) and overall (3.12±0.22 vs. 4.46±0.25; p=0.03). There was a trend towards a decrease in AIF expression between stage III/IV vs. I/II tumors in tissue collected directly from the tumor in the cytoplasm (2.55±0.24 vs. 3.56±0.26; p=0.12), the nucleus (1.39±0.25 vs. 2.73±0.63; p=0.14) and overall (2.79±0.38 vs. 3.90±0.37; p=0.22). Conclusion: AIF expression is decreased in metastatic colon cancer. The main differences occur in the normal mucosa adjacent to the tumor.

No significant financial relationships to disclose.

[Ying-Yang (YY-1) expression and Fas in biopsies of children with type IV lupus nephritis correlates with the clinical condition]

BACKGROUND

It has been demonstrated that Fasmediated apoptosis participates in the physiopathology of lupus nephritis, although it is not clear whether it contributes to the development of the tissue damage.Since YY-1 down regulates Fas in cancer cell lines, it is reasonable to consider that this transcription factor may control Fas expression in lupus nephritis. The objective was to determine the correlation between YY-1 and Fas expression in renal biopsies from children with type IV lupus nephritis, and their association with the clinical condition of the patients.

MATERIAL AND METHODS

Eighteen biopsies from children with type IV lupus nephritis and 5 controls were studied. Fas and YY-1 expression were determined by immunochemistry and quantified by densytometric analysis. The clinical conditions at the moment the biopsy were obtained from the clinical records and the results were analyzed through a one-way ANOVA with p<0.005.

RESULTS

The results of the densytometric analysis showed an inverse relationship between YY-1 and Fas expression. YY-1 was grouped according to the intensity of expression in low, moderate and high and compared with the expression of Fas. The lupus nephritis biopsies, which revealed high expression of YY-1, corresponded to patients with less number of clinical complications,better outcome and fewer alterations on renal function.In contrast, low expression of YY-1 correlated with high Fas expression and worst clinical conditions.

CONCLUSIONS

The present study suggests that YY-1regulates Fas expression in lupus nephritis and that it is associated with the clinical outcome of the patients,although further studies are necessary to determine weather it factor may serve as a prognosis factor. This is the first evidence of YY-1 participation in the physiopathology of lupus nephritis.

Chemotherapeutic drugs sensitize cancer cells to TRAIL-mediated apoptosis: up-regulation of DR5 and inhibition of Yin Yang 1

Several chemotherapeutic drugs in combination with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) result in reversal of resistance to TRAIL-mediated apoptosis through up-regulation of DR5 expression. The promoter of DR5 has one putative binding site for the transcription repressor Yin Yang 1 (YY1), and thus, we hypothesized that the sensitizing drugs may inhibit YY1. We have found that treatment of tumor cells with various chemotherapeutic drugs inhibited nuclear factor-kappaB. We examined whether drugs also inhibit YY1 activity and whether YY1 inhibition correlates with up-regulation of DR5 expression and sensitization of cells to TRAIL-induced apoptosis. The TRAIL- and drug-resistant prostate carcinoma PC-3 cell line was treated with CDDP, VP-16, ADR, and vincristine. DR5 luciferase reporter constructs and small interfering RNA against YY1 were used to determine the role of YY1 in DR5 transcription. Pretreatment of PC-3 cells and other tumor cell lines with various chemotherapeutic drugs sensitized the cells to TRAIL-induced apoptosis concurrently with up-regulation of DR5 expression and inhibition of YY1 expression and its DNA-binding activity. The baseline luciferase activity in PC-3 cells transfected with the wild-type DR5 reporter was significantly augmented in cells transfected with DR5 constructs carrying deletions or mutation in the YY1-binding site. Treatment with drug enhanced DR5 wild-type luciferase activity, with no increase in cells transfected with the YY1-deleted or YY1-mutated constructs. Cells transfected with YY1 small interfering RNA showed up-regulation of DR5 expression and sensitization to TRAIL-mediated apoptosis. The findings provide evidence that drug-induced sensitization of tumor cells to TRAIL is mediated, in part, by inhibition of the transcription repressor YY1 and up-regulation of DR5 expression. Hence, YY1 may be a potential therapeutic target to reverse resistance to TRAIL-induced apoptosis.