Endoplasmic reticulum protein BI-1 modulates unfolded protein response signaling and protects against stroke and traumatic brain injury

Bax-Inhibitor-1 (BI-1) is an evolutionarily conserved cytoprotective protein that resides in membranes of the endoplasmic reticulum (ER). BI-1's cytoprotective activity is manifested in the context of ER stress, with previous studies showing that BI-1 modulates several ER-associated functions, including Unfolded Protein Response (UPR) signaling. Here we investigated the role of BI-1 in neuroprotection by generating transgenic mice in which BI-1 was constitutively expressed from a neuronal-specific promoter. Cultured primary cortical neurons from BI-1 transgenic mouse embryos exhibited greater resistance to cell death induced by agents known to cause ER stress compared to their non-transgenic counterparts. While brain morphology and vasculature of BI-1 mice appeared to be unchanged from normal non-transgenic mice, BI-1 transgenic mice showed reduced brain lesion volumes and better performance in motoric tests, compared with non-transgenic littermates, in two models of acute brain injury: stroke caused by middle cerebral artery occlusion (MCAO) and traumatic brain injury (TBI) caused by controlled cortical impact. Furthermore, brain tissue from BI-1 transgenic mice showed reduced levels of apoptotic cells and reduced induction of markers of ER stress after brain injury, including CHOP protein expression. In summary, our findings demonstrate that enforced neuronal expression of BI-1 reduces ER stress and provides protection from acute brain injury, suggesting that strategies for enhancing BI-1 expression or activity should be considered for development of new therapies for counteracting the consequences of stroke and acute brain trauma.

A role for ATF2 in regulating MITF and melanoma development

The transcription factor ATF2 has been shown to attenuate melanoma susceptibility to apoptosis and to promote its ability to form tumors in xenograft models. To directly assess ATF2's role in melanoma development, we crossed a mouse melanoma model (Nras(Q61K)::Ink4a⁻/⁻) with mice expressing a transcriptionally inactive form of ATF2 in melanocytes. In contrast to 7/21 of the Nras(Q61K)::Ink4a⁻/⁻ mice, only 1/21 mice expressing mutant ATF2 in melanocytes developed melanoma. Gene expression profiling identified higher MITF expression in primary melanocytes expressing transcriptionally inactive ATF2. MITF downregulation by ATF2 was confirmed in the skin of Atf2⁻/⁻ mice, in primary human melanocytes, and in 50% of human melanoma cell lines. Inhibition of MITF transcription by MITF was shown to be mediated by ATF2-JunB-dependent suppression of SOX10 transcription. Remarkably, oncogenic BRAF (V600E)-dependent focus formation of melanocytes on soft agar was inhibited by ATF2 knockdown and partially rescued upon shMITF co-expression. On melanoma tissue microarrays, a high nuclear ATF2 to MITF ratio in primary specimens was associated with metastatic disease and poor prognosis. Our findings establish the importance of transcriptionally active ATF2 in melanoma development through fine-tuning of MITF expression.

Expression of p21 protein predicts clinical outcome in DLBCL patients older than 60 years treated with R-CHOP but not CHOP: a prospective ECOG and Southwest Oncology Group correlative study on E4494

PURPOSE

To prospectively investigate the prognostic significance of p21 and p53 expression in diffuse large B-cell lymphoma in the context of the U.S. Intergroup trial comparing conventional cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy to rituximab-CHOP (R-CHOP) induction, with or without maintenance rituximab.

EXPERIMENTAL DESIGN

Immunohistochemical staining of 197 paraffin-embedded biopsy specimens was scored by an independent panel of experts.

RESULTS

The cyclin-dependent kinase inhibitor, p21, was expressed in 55% of cases examined. In a multivariable analysis adjusting for International Prognostic Index score and BCL2 status, p21 expression was a significant, independent, favorable predictive factor for failure-free survival (relative risk, 0.3; P = 0.001) and overall survival (relative risk, 0.3; P = 0.003) for patients treated with R-CHOP. Expression of p21 was not predictive of outcome for CHOP-treated patients. Only p21-positive cases benefited from the addition of rituximab to CHOP. Among p21-positive patients, treatment with R-CHOP was associated with a higher failure-free survival rate at 5 years compared with CHOP (61% versus 24%; P = 0.01). In contrast, no significant differences were detected in failure-free survival according to treatment arm for p21-negative patients. Expression of p53, alone or in combination with p21, did not predict for outcome in univariable or multivariable analyses.

CONCLUSIONS

In this study, p21 protein expression emerged as an important independent predictor of a favorable clinical outcome when rituximab was added to CHOP therapy. These data suggest that rituximab-related effects on lymphoma survival pathways may be functionally linked to p21 activity.

Pretransplantation cellular alloreactivity is predictive of acute graft rejection and 1-year graft function in kidney transplant recipients

OBJECTIVE

To study cellular alloimmunity in kidney allograft recipients using an interferon-gamma enzyme-linked immunosorbent spot assay (ELISPOT).

MATERIAL AND METHODS

Donor splenocyte peripheral blood mononuclear cells were obtained during kidney recovery in 53 kidney recipients including 11 with positive panel-reactive antibodies pretransplantation. For ELISPOT data analysis, the spot number, size, and intensity were calculated, reflecting the volume of cytokine secretion at the single-cell level. Results were recalculated as the ratio of the values observed for donor-stimulated to unstimulated recipient cells corrected for residual donor activity.

RESULTS

Significantly greater pretransplantation donor-stimulated activity was observed in recipients who experienced an acute rejection episode (ARE) within 1 year (P < .05). Mean change in spot number, size, and intensity in patients without or with AREs was 0.99 vs 3.33, 1.60 vs 6.05, and 1.40 vs 6.31, respectively. The assessed parameters were prognostic of high risk of ARE: 1.5-fold increase in spot number (ARE incidence, 52% vs 9%), 2.5-fold increase in spot size (ARE incidence, 53% vs 13%), and 2.7-fold increase in spot intensity (ARE incidence, 52% vs 9%). The 3 parameters correlated with 1-year serum creatinine concentration (P < .05). In 14 recipients, AREs could have been predicted in 11 using pretransplantation ELISPOT results, and in only 2 on the basis of panel-reactive antibodies.

CONCLUSION

The ELISPOT-determined capacity of donor-induced reactivity observed in recipient cells obtained just before transplantation is predictive of risk of graft rejection and 1-year allograft function.

Salmonella typhimurium engineered to produce CCL21 inhibit tumor growth

Intravenously-applied bacteria tend to accumulate in tumors and can sporadically lead to tumor regression. Systemic administration of attenuated Salmonella typhimurium is safe and has shown no significant adverse effects in humans. The purpose of this study was to test the hypothesis that engineering S. typhimurium to express a chemokine, CCL21, would increase anti-tumor activity. We engineered an attenuated strain of S. typhimurium to produce the chemokine CCL21. Attenuated S. typhimurium expressing CCL21 significantly inhibited the growth of primary tumors and pulmonary metastases in preclinical models of multi-drug-resistant murine carcinomas, while control bacteria did not. Histological analysis of tumors showed marked inflammatory cell infiltrates in mice treated with CCL21-expressing but not control bacteria. Levels of cytokines and chemokines known to be induced by CCL21 [e.g., interferon-gamma (INFgamma), CXCL9, and CXCL10] were significantly elevated in tumors of mice treated with CCL21-expressing but not control S. typhimurium. The anti-tumor activity was found to be dependent on CD4- and CD8-expressing cells, based on antibody-mediated in vivo immuno-depletion experiments. Anti-tumor activity was achieved without evidence of toxicity. In summary, chemokine-expressing, attenuated bacteria may provide a novel approach to cancer immunotherapy for effective and well-tolerated in vivo delivery of immunomodulatory proteins.

Image analysis algorithms for immunohistochemical assessment of cell death events and fibrosis in tissue sections

Cell death is of broad physiological and pathological importance, making quantification of biochemical events associated with cell demise a high priority for experimental pathology. Fibrosis is a common consequence of tissue injury involving necrotic cell death. Using tissue specimens from experimental mouse models of traumatic brain injury, cardiac fibrosis, and cancer, as well as human tumor specimens assembled in tissue microarray (TMA) format, we undertook computer-assisted quantification of specific immunohistochemical and histological parameters that characterize processes associated with cell death. In this study, we demonstrated the utility of image analysis algorithms for color deconvolution, colocalization, and nuclear morphometry to characterize cell death events in tissue specimens: (a) subjected to immunostaining for detecting cleaved caspase-3, cleaved poly(ADP-ribose)-polymerase, cleaved lamin-A, phosphorylated histone H2AX, and Bcl-2; (b) analyzed by terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling assay to detect DNA fragmentation; and (c) evaluated with Masson's trichrome staining. We developed novel algorithm-based scoring methods and validated them using TMAs as a high-throughput format. The proposed computer-assisted scoring methods for digital images by brightfield microscopy permit linear quantification of immunohistochemical and histochemical stainings. Examples are provided of digital image analysis performed in automated or semiautomated fashion for successful quantification of molecular events associated with cell death in tissue sections.

Breast cancer subtypes and response to docetaxel in node-positive breast cancer: use of an immunohistochemical definition in the BCIRG 001 trial

PURPOSE

To investigate the prognostic and predictive significance of subtyping node-positive early breast cancer by immunohistochemistry in a clinical trial of a docetaxel-containing regimen.

METHODS

Pathologic data from a central laboratory were available for 1,350 patients (91%) from the BCIRG 001 trial of docetaxel, doxorubicin, and cyclophosphamide (TAC) versus fluorouracil, doxorubicin, and cyclophosphamide (FAC) for operable node-positive breast cancer. Patients were classified by tumor characteristics as (1) triple negative (estrogen receptor [ER]-negative, progesterone receptor [PR]-negative, HER2/neu [HER2]-negative), (2) HER2 (HER2-positive, ER-negative, PR-negative), (3) luminal B (ER-positive and/or PR-positive and either HER2-positive and/or Ki67(high)), and (4) luminal A (ER-positive and/or PR-positive and not HER2-positive or Ki67(high)), and assessed for prognostic significance and response to adjuvant chemotherapy.

RESULTS

Patients were subdivided into triple negative (14.5%), HER2 (8.5%), luminal B (61.1%), and luminal A (15.9%). Three-year disease-free survival (DFS) rates (P values with luminal B as referent) were 67% (P < .0001), 68% (P = .0008), 82% (referent luminal B), and 91% (P = .0027), respectively, with hazard ratios of 2.22, 2.12, and 0.46. Improved 3-year DFS with TAC was found in the luminal B group (P = .025) and a combined ER-positive/HER2-negative group treated with tamoxifen (P = .041), with a marginal trend in the triple negatives (P = .051) and HER2 (P = .068) subtypes. No DFS advantage was seen in the luminal A population.

CONCLUSION

A simple immunopanel can divide breast cancers into biologic subtypes with strong prognostic effects. TAC significantly complements endocrine therapy in patients with luminal B subtype and, in the absence of targeted therapy, is effective in the triple-negative population.

Multiple antigen detection (MAD) western blotting

A variation of ECL immunodetection method permits sequential detection of multiple antigens (MAD) on a single protein blot without stripping previously bound antibodies. Because antibody stripping is not involved, immobilized proteins are not lost from the membrane, which permits multiple sequential reprobings of the same membrane with different primary antibodies (> or = 12) and retention of strong signal intensities for all antibody probings. This procedure utilizes horseradish peroxidase (HRPase)-based detection with both chemiluminescent and colorimetric substrates. Initial incubation of the blot with secondary antibody followed by colorimetric development prior to probing the blot with primary antibodies markedly reduces background intensities in ECL-based detection procedures and permits sequential use of antibodies derived from a single species. By allowing large amounts of data to be obtained from a single blot, MAD immunoblotting has the potential to markedly streamline the work required to compare the expression levels of several proteins within biological samples. This technique could be particularly valuable for analyzing cellular populations that are difficult to isolate in large numbers or clinical specimens where the amount of protein samples is limited or available on a one-time basis.

Bcl-B expression in human epithelial and nonepithelial malignancies

PURPOSE

Apoptosis plays an important role in neoplastic processes. Bcl-B is an antiapoptotic Bcl-2 family member, which is known to change its phenotype upon binding to Nur77/TR3. The expression pattern of this protein in human malignancies has not been reported.

EXPERIMENTAL DESIGN

We investigated Bcl-B expression in normal human tissues and several types of human epithelial and nonepithelial malignancy by immunohistochemistry, correlating results with tumor stage, histologic grade, and patient survival.

RESULTS

Bcl-B protein was strongly expressed in all normal plasma cells but found in only 18% of multiple myelomas (n = 133). Bcl-B immunostaining was also present in normal germinal center centroblasts and centrocytes and in approximately half of diffuse large B-cell lymphoma (n = 48) specimens, whereas follicular lymphomas (n = 57) did not contain Bcl-B. In breast (n = 119), prostate (n = 66), gastric (n = 180), and colorectal (n = 106) adenocarcinomas, as well as in non-small cell lung cancers (n = 82), tumor-specific overexpression of Bcl-B was observed. Bcl-B expression was associated with variables of poor prognosis, such as high tumor grade in breast cancer (P = 0.009), microsatellite stability (P = 0.0002), and left-sided anatomic location (P = 0.02) of colorectal cancers, as well as with greater incidence of death from prostate cancer (P = 0.005) and shorter survival of patients with small cell lung cancer (P = 0.009). Conversely, although overexpressed in many gastric cancers, Bcl-B tended to correlate with better outcome (P = 0.01) and more differentiated tumor histology (P < 0.0001).

CONCLUSIONS

Tumor-specific alterations in Bcl-B expression may define subsets of nonepithelial and epithelial neoplasms with distinct clinical behaviors.

Inhibition of tumor growth using salmonella expressing Fas ligand

Intravenous administration of bacteria leads to their accumulation in tumors and to sporadic tumor regression. We therefore explored the hypothesis that Salmonella typhimurium engineered to express the proapoptotic cytokine Fas ligand (FasL) would exhibit enhanced antitumor activity. Immunocompetent mice carrying tumors derived from syngeneic murine D2F2 breast carcinoma or CT-26 colon carcinoma cells were treated intravenously with FasL-expressing S. typhimurium or with phosphate-buffered saline (PBS; control). Treatment with FasL-expressing S. typhimurium inhibited growth of primary tumors by an average of 59% for D2F2 tumors and 82% for CT-26 tumors (eg, at 25 days after initial treatment, mean volume of PBS-treated CT-26 colon carcinomas = 1385 mm(3) and of S. typhimurium FasL-treated CT-26 tumors = 243 mm(3), difference = 1142 mm(3), 95% confidence interval = 800 mm(3) to 1484 mm(3), P < .001). Pulmonary D2F2 metastases (as measured by lung weight) were reduced by 34% in S. typhimurium FasL-treated mice compared with PBS-treated mice. FasL-expressing S. typhimurium had similar effects on growth of murine B16 melanoma tumors in wild-type mice but not in lpr/lpr mice, which lack Fas, or in mice with disrupted host inflammatory responses. Antitumor activity was achieved without overt toxicity. These preclinical results raise the possibility that using attenuated S. typhimurium to deliver FasL to tumors may be an effective and well-tolerated therapeutic strategy for some cancers.

Development of diabesity in mice with neuronal deletion of Shp2 tyrosine phosphatase

Obesity and diabetes, termed "diabesity," are serious health problems that are increasing in frequency. However, the molecular mechanisms and neuronal regulation of these metabolic disorders are not fully understood. We show here that Shp2, a widely expressed Src homology 2-containing Tyr phosphatase, plays a critical role in the adult brain to control food intake, energy balance, and metabolism. Mice with a neuron-specific, conditional Shp2 deletion were generated by crossing a pan-neuronal Cre-line (CRE3) with Shp2(flox/flox) mice. These congenic mice, CRE3/Shp2-KO, developed obesity and diabetes and the associated pathophysiological complications that resemble those encountered in humans, including hyperglycemia, hyperinsulinemia, hyperleptinemia, insulin and leptin resistance, vasculitis, diabetic nephropathy, urinary bladder infections, prostatitis, gastric paresis, and impaired spermatogenesis. This mouse model may help to elucidate the molecular mechanisms that lead to the development of diabesity in humans and provide a tool to study the in vivo complications of uncontrolled diabetes.

Risk factors for glucose metabolism disorders after kidney transplantation with uneventful course

A wide range of glucose metabolic disorders (GMDs) often arise after renal transplantation that predispose to graft dysfunction, infections, and cardiovascular disease. This study evaluated the risk factors for GMDs among 50 patients including 30 males and overall mean age 44.9 +/- 12.1 years. All 50 subjects displayed normal glucose tolerance tests pretransplantation and no family history of diabetes. They were selected from the 99 consecutive patients transplanted from April 2005 to January 2006 based upon uneventful posttransplantation course, without rejection episodes or hepatitis C virus (HCV) infections. The study concentrated on risk factors originating during the dialysis period. Even in this selected group, the risk of posttransplant GMD development was high (28%). Patients with GMDs showed significantly worse renal function at 1 month after transplantation (serum creatinine concentration: 1.70 +/- 1.67 mg/dL in the GMD group vs. 1.44 +/- 0.96 mg/dL in the group without GMDs [P = .027] and eGFR, 56.68 +/- 22.70 mL/min/1.73 m(2) versus 71.29 +/- 27.37 mL/min/1.73 m(2), respectively, [(P = .099)]. In a logistic regression model, a statistically significant difference between the groups was shown only for cold ischemia time (P = .037). In the logistic regression model with two independent variables, statistical significance was observed (P = .038) for body mass index at the time of transplantation. In this model, a lower pretransplant serum insulin concentration showed an influence that bordered on significance (P = .074). This study confirmed that the etiology of GMD after kidney transplantation is multifactorial, and at least in part connected with the pre-transplantation period.

Attenuated Salmonella engineered to produce human cytokine LIGHT inhibit tumor growth

Intravenously administered bacteria reportedly accumulate in tumors. Furthermore, systemic administration of attenuated Salmonella typhimurium has little or no significant side-effects in humans. Consequently, we engineered such bacteria to improve their oncolytic activity by stably inserting a gene encoding LIGHT, a cytokine known to promote tumor rejection. Unlike control bacteria, attenuated S. typhimurium expressing LIGHT inhibited growth of primary tumors, as well as the dissemination of pulmonary metastases, in various mouse tumor models employing murine carcinoma cell lines in immunocompetent mice. Antitumor activity was achieved without significant toxicity and was associated with infiltration of inflammatory cells and dependent on the LIGHT receptors, herpes virus entry mediator (HVEM), and lymphotoxin-beta receptor (LTbetaR). These findings provide evidence that nonvirulent bacteria can be exploited as targeting vehicles for local generation of therapeutic proteins in tumors.

Triterpenoids display single agent anti-tumor activity in a transgenic mouse model of chronic lymphocytic leukemia and small B cell lymphoma

Background

The synthetic triterpenoid 2-Cyano-3,12-Dioxooleana-1,9-Dien-28-Oic Acid (CDDO) and derivatives display anti-tumor activity against a variety of cultured tumor cell lines and in mouse xenografts. In this report, we have studied the effects of CDDO and its imidazolide derivative (CDDO-Im) on chronic lymphocytic leukemia (CLL), using patients' CLL cells and a mouse model of CLL and small B cell lymphoma (SBL).

Principal Findings

CDDO and CDDO-Im efficiently induced apoptosis of malignant human and mouse B-cells ex vivo, although CDDO-Im was over 10-fold more potent than CDDO. Treating mice with CLL/SBL with liposome-formulated CDDO or CDDO-Im resulted in significant reductions of B cells in blood, spleen and lung. CDDO-Im was shown to be more potent than CDDO, while treatment with empty liposomes had no impact on disease. CDDO-Im treatment initially resulted in an increase of circulating B cells, which correlates with a reduction in resident lymphocytes in spleen, and lungs, suggesting that CDDO-Im induces mobilization of tumor cells from lymphoid organs and infiltrated tissues into the circulation. Analysis of blood cells recovered from treated mice also showed that CDDO-Im is a potent inducer of tumor cells death in vivo. Furthermore, CDDO-Im efficiently eradicated mouse CLL/SBL cells but had little effect on the viability of normal B and T cells in vivo.

Significance

The presented data demonstrate that triterpenoids CDDO and CDDO-Im reduce leukemia and lymphoma burden in vivo in a transgenic mouse model of CLL/SBL, and support the clinical testing of CDDO-based synthetic triterpenoids in patients with CLL.

Prognostic significance of p53/p21 expression in DLBCL treated with CHOP or R-CHOP: A correlative study of E4494

8038

Background: P21 is a downstream effector protein of p53 that induces cell cycle arrest by inhibiting cyclin/cyclin dependent kinase (cdK) complexes. In this prospective correlative study, we investigated the prognostic significance of p21, p53, Bcl-6, and Bcl-2 in diffuse large B cell lymphoma (DLBCL) in the context of E4494, a randomized trial comparing conventional CHOP to rituximab(R)-CHOP induction, and maintenance R (MR) to observation for responding patients. Methods: Protein expression was quantified by immunohistochemical (IHC) staining of 198 DLBCL paraffin-embedded biopsy specimens and scored by an expert panel of hematopathologists. Results: No differences in the distribution of patient characteristics were detected between p21+ and p21- cases and between p53+ and p53- cases as well as across treatment arms. Among all study patients, there were no differences in clinical outcomes between p21+ and p21- cases. However, when analyzed by induction arm (removing the effect of MR), R-CHOP patients had marginally better FFS (p=0.06) if p21+; among CHOP-treated patients, p21 status had no effect on outcome. For R-CHOP patients but NOT CHOP patients, p21+ was an independent, favorable prognostic factor after adjusting for Bcl-6, IPI and Bcl-2 in multivariate analysis (FFS relative risk 0.3; p=0.003; OS relative risk 0.4; p=0.02). P21+ patients treated with R-CHOP had higher %FFS at 5 years compared to p21+ patients treated with CHOP (61 ± 7% vs. 24 ± 7%; p=0.007) but p21- R-CHOP and CHOP patients had similar FFS (37 ± 7% vs. 35 ± 7%; p=0.64). P53 staining (+ scored as either >20% or 50%) did not predict for FFS or OS in uni- or multivariate analyses. The p53+/p21- phenotype, a possible surrogate for mutated p53, was not prognostic. Further, no significant correlation was seen between p53 and p21 expression by IHC. Conclusions: These data suggest that p21 expression by IHC predicts for favorable outcome in older DLBCL patients treated with R-CHOP but not in those treated with CHOP. Furthermore, p21+ identifies patients who benefit from the addition of rituximab to CHOP. Complex interactions between p53, p21, and Bcl-6, as well as other unknown pathways, may account for this treatment-related effect and should be further investigated.

[Table: see text]

Expression of Bax and Bcl2 proteins in small cell lung cancer (SCLC)

18189

Background: Bax and Bcl2 proteins are members of Bcl-2 family which plays a critical role in the regulation of apoptosis. There are few data on the occurrence and clinical relevance of these proteins in SCLC. Methods: We have analyzed expression of Bax and Bcl2 in 86 SCLC patients. All patients had limited disease and were treated with surgery followed by chemotherapy between 1982 and 2001 (median follow up 2 years). In all cases the diagnosis of SCLC was established only after the examination of surgical specimen. This series included 59 males and 22 females, 11 T1, 46 T2, 13 T3 and 11 T4 tumors, 41 N0, 15 N1, 24 N2 and 1 N3. Expression of both proteins was evaluated by immunohistochemistry and scored, taking into account proportion of cells with positive staining and staining intensity. H-score was calculated as a proportion of positive cells times staining intensity. Continues data on H-score were used to assess relationships with clinical data. Results: Median H-scores for Bax and Bcl2 were 70 (range 0–300) and 90 (range 0–300) respectively. The positive immunostaining rates (cut-off point of 10%) for Bax and Bcl-2 in the entire group were 81% and 79% respectively. Bax and Bcl-2 expression did not correlate with any clinicopathological parameters such as age, tumor size, lymph node involvement and stage of the disease. Survival was not influenced by expression of Bax (p=0.6) or Bcl2 (p=0.86). There was a significant positive correlation between Bax and Bcl2 expression rates (p=0.018, regression coefficient 0.23). Conclusions: Bax an Bcl2 proteins are commonly overexpressed in SCLC, with tendency for co-expression. Clinical relevance of these markers is questionable in this patient cohort.

No significant financial relationships to disclose.

BCIRG 001 molecular analysis: Identification of prognostic factors in patients (pts) receiving adjuvant therapy for node- positive (N+) breast cancer (BC)

525

Background: BCIRG 001 (1,491 pts) demonstrated significant superiority of docetaxel/doxorubicin/cyclophosphamide (TAC) over fluorouracil/doxorubicin/cyclophosphamide (FAC) given as adjuvant therapy for N+ operable BC in terms of disease-free survival (DFS) and overall survival (OS) (Martin et al, N Eng J Med, 2005). This ancillary study was aimed to identify tumor-associated factors related to DFS and OS. Methods: Formalin-fixed primary tumors from pts in BCIRG 001 were analysed by immunohistochemistry. Protocol- specified assessment of histological grade (GR), tumor size (TS), estrogen (ER) and progesterone receptors (PR), lymph node status (LN), HER2, MUC1, Mib, p53, Bcl-2, Bax, Bcl-X, Bag-1, tubulin β isotypes II, III and IV, tau protein and detyrosinated a tubulin was performed. Parameters were scored as the percentage of positive cells and analysed as lower or greater than median values. The samples were randomly split into training (2/3) and validation (1/3) sets. Associations between selected parameters and DFS or OS were tested through univariate analyses using the Kaplan Meier method (log-rank test) on the training set. A backward stepwise Cox regression analysis was performed to identify the final model of prognostic factors on the training set. Multivariate analyses were applied to the validation set. Results: 1,350 samples were split into a training (n=906) and a validation (n=444) set. In univariate GR, TS, LN, ER and PR, Mib, tau protein and HER2 were correlated with DFS in both sets. In multivariate ER, PR, TS, LN, Mib (all p<0.01) and tau (p=0.043) were significantly associated with DFS in the training set. In univariate GR, TS, LN, ER and PR, Mib, MUC1, Bcl-2, tubulin III and IV and tau were correlated with OS in both sets, with a trend for p53. In multivariate ER, TS, LN, Mib, p53 (all p<0.01) and PR (p=0.028) were independently correlated with OS in the training set. Conclusions: These data suggest that tau and p53 are independent markers of DFS and OS, respectively, while Mib is correlated with both DFS and OS in pts receiving these forms of adjuvant chemotherapy for N+ BC. Complementary analyses will be presented.

No significant financial relationships to disclose.

Claudin-1 immunohistochemistry for distinguishing malignant from benign epithelial lesions of prostate

BACKGROUND

Claudins are a family of approximately 23 integral membrane tight junction (TJ) proteins that maintain cell polarity and paracellular barrier functions in epithelial and endothelial cells. Although Claudin-1 was demonstrated to be typically downregulated in various cancers, the precise expression patterns of this protein in normal and neoplastic tissues remain poorly characterized.

METHODS

Using immunohistochemistry, the expression of Claudin-1 was investigated in prostate tissue samples arranged in a tissue microarray (TMA) format and comprising elements of normal prostatic epithelium (n = 6), benign prostatic hyperplasia (BPH; n = 38), prostatic intraepithelial neoplasia (PIN; n = 11), and prostate adenocarcinoma (n = 48). The Claudin-1 expression pattern was compared with that of the basal cell-specific markers, p63, and HMW cytokeratin (34betaE12), by employing double-labeling techniques in conjunction with image analysis methods utilizing color deconvolution algorithms.

RESULTS

In benign prostatic epithelium, pronounced Claudin-1 expression was observed in the basal cell layer with no staining in luminal cells. Prostate adenocarcinoma specimens from 98% (47/48) patients lacked Claudin-1 immunostaining, and no cases contained >5% immunopositive tumor cells.

CONCLUSIONS

Claudin-1 immunohistochemistry should be considered for use as a new diagnostic tool for distinguishing malignant from benign lesions of the prostate.

Ubiquitin-conjugating enzyme Ubc13 is a critical component of TNF receptor-associated factor (TRAF)-mediated inflammatory responses

Ubc13 is a ubiquitin-conjugating enzyme responsible for noncanonical ubiquitination of TNF receptor-associated factor (TRAF)-family adapter proteins involved in Toll-like receptor and TNF-family cytokine receptor signaling, which are regulators of innate immunity. Gene ablation was used to study the function of Ubc13 in mice. Whereas homozygous ubc13 gene disruption resulted in embryonic lethality, heterozygous ubc13(+/-) mice appeared normal, without alterations in immune cell populations. Haploinsufficient ubc13(+/-) mice were resistant to lipopolysaccharide-induced lethality, and demonstrated reduced in vivo ubiquitination of TRAF6. Macrophages and splenocytes isolated from ubc13(+/-) mice exhibited reduced lipopolysaccharide-inducible cytokine secretion and impaired activation of TRAF-dependent signal transduction pathways (NF-kappaB, JNK, and p38 MAPK). These findings document a critical role for Ubc13 in inflammatory responses and suggest that agents reducing Ubc13 activity could have therapeutic utility.

Nur77 converts phenotype of Bcl-B, an antiapoptotic protein expressed in plasma cells and myeloma

Defects in apoptosis mechanisms play important roles in malignancy and autoimmunity. Orphan nuclear receptor Nur77/TR3 has been demonstrated to bind antiapoptotic protein Bcl-2 and convert it from a cytoprotective to a cytodestructive protein, representing a phenotypic conversion mechanism. Of the 6 antiapoptotic human Bcl-2 family members, we found that Nur77/TR3 binds strongest to Bcl-B, showing selective reactivity with Bcl-B, Bcl-2, and Bfl-1 but not Bcl-X(L), Mcl-1, or Bcl-W. Nur77 converts the phenotype of Bcl-B from antiapoptotic to proapoptotic. Bcl-B is prominently expressed in plasma cells and multiple myeloma. Endogenous Bcl-B associates with endogenous Nur77 in RPMI 8226 myeloma cells, where RNA interference experiments demonstrated dependence on Bcl-B for Nur77-induced apoptosis. Furthermore, a Nur77-mimicking peptide killed RPMI 8226 myeloma cells through a Bcl-B-dependent mechanism. Because Bcl-B is abundantly expressed in plasma cells and some myelomas, these findings raise the possibility of exploiting the Nur77/Bcl-B mechanism for apoptosis for eradication of autoimmune plasma cells or myeloma.

Mammalian dap3 is an essential gene required for mitochondrial homeostasis in vivo and contributing to the extrinsic pathway for apoptosis

Death-associated protein-3 (DAP3) is a GTP binding protein previously implicated in both intramitochondrial protein synthesis and apoptosis. To explore the in vivo roles of DAP3, we generated and characterized DAP3-deficient mice. Homozygous dap3-/- embryos died at approximately day 9.5 in utero. The dap3-/- embryos and placentas were markedly shrunken. Embryos had arrested development, displaying severe growth restriction and lack of axial turning. Transmission electron microscopy analysis revealed abnormal, shrunken mitochondria with swollen crystae in dap3-/- embryos. Levels of cytochrome c oxidase-I, a protein encoded in the mitochondrial genome, were reduced in dap3-/- embryos, consistent with a role for DAP3 in intramitochondrial protein synthesis. A requirement for DAP3 in mitochondrial respiration was also revealed by oxygen consumption measurements using cultured cells treated with DAP3-specific small interfering RNA (siRNA). Studies of cultured cells from dap3-/- embryos confirmed a role in apoptosis induced by stimuli that trigger the extrinsic (TNFalpha, TRAIL, anti-Fas antibody) but not intrinsic (mitochondrial) cell death pathway. Thus, DAP3 joins a growing list of bifunctional proteins that play roles in normal mitochondrial physiology and in apoptosis.

Immunoproteomics strategy for automation of chemoresistance and chemosensitivity array

20076

Background: Chemotherapy sensitivity and resistance assays (CSRAs) often guide therapeutic regimen selection based on patient cancer cells response to chemotherapeutics in culture. Current CSRAs rely on highly time- and skill- dependent biochemical and microscopic endpoint assays of apoptosis. Instead, the assay under development uses immunoproteomic array readout of biomarkers. Such automation may broaden the use of CSRAs for guiding clinical use of increasingly costly chemotherapeutic options. Methods: Specimens from 30 ovarian cancer patients were cultured with and without cisplatinum according to established CSRA procedures (http://weisenthal.org/w_ovarian_cp.pdf). Cells pelleted and fixed at experimental points (0 and 96 hrs cisplatin, and 96 hrs non-treated) were paraffin embedded for construction of immunoproteomic microarrays. A panel of 57 NIH cancer cell lines was similarly arrayed. Protein profiling is performed with monospecific antibodies for 35 select markers of cell cycle, apoptosis, cell signalling, and transcription. Immunostaining results, including rate of cell death and marker expression level are quantitated manually (immunoscore assigned for cell core) and automatically (algorithm by Aperio, Inc). Results: Evaluation of readouts differentiates responders from non-responders aiming to predict clinical chemotherapy outcome. For a subset of imunoproteomic markers, observed expression corresponds to either induced apoptosis or to cisplatin resistance. Selected markers were subjected to cytologic analysis and time line westerns; results corroborate protein profiling data. Correspondence to the results of the classic CSRAs and individual patient therapeutic response will be unblinded. Conclusions: Use of immunoproteomic arrays to replicate classic CSRAs by establishing concordant results may allow automated guidance for chemotherapeutic choices.

[Table: see text]

Expression of BAG-1 protein correlates with aggressive behavior of prostate cancers

BACKGROUND

Differences in tumor behavior, ranging from indolent to aggressive, create a need for novel prognostic biomarkers. BAG-1 is a co-chaperone that regulates the activity of Hsp70, Bcl-2, Raf-1, growth factor, and steroid receptors (e.g., the Androgen Receptor).

METHODS

Using immunohistochemical method, we explored BAG-1 expression in prostate cancers and its association with clinicopathological parameters.

RESULTS

BAG-1 immunostaining was elevated in prostate cancer compared to normal prostatic epithelium. Higher nuclear BAG-1 in hormone-refractory (n = 34) compared to localized untreated tumors (n = 58) (P < 0.0001) suggested that upregulation of the nuclear isoform may contribute to disease progression. In 64 early-stage patients (T2N0M0) treated with external-beam irradiation, cytosolic BAG-1 correlated with higher pretreatment levels of serum Prostate specific antigen (P = 0.04) and shorter time to disease progression (P = 0.00004).

CONCLUSIONS

Increased cytosolic and nuclear BAG-1 expression may denote more aggressive variants of prostate cancer.

Framework for parsing, visualizing and scoring tissue microarray images

Increasingly automated techniques for arraying, immunostaining, and imaging tissue sections led us to design software for convenient management, display, and scoring. Demand for molecular marker data derived in situ from tissue has driven histology informatics automation to the point where one can envision the computer, rather than the microscope, as the primary viewing platform for histopathological scoring and diagnoses. Tissue microarrays (TMAs), with hundreds or even thousands of patients' tissue sections on each slide, were the first step in this wave of automation. Via TMAs, increasingly rapid identification of the molecular patterns of cancer that define distinct clinical outcome groups among patients has become possible. TMAs have moved the bottleneck of acquiring molecular pattern information away from sampling and processing the tissues to the tasks of scoring and results analyses. The need to read large numbers of new slides, primarily for research purposes, is driving continuing advances in commercially available automated microscopy instruments that already do or soon will automatically image hundreds of slides per day. We reviewed strategies for acquiring, collating, and storing histological images with the goal of streamlining subsequent data analyses. As a result of this work, we report an implementation of software for automated preprocessing, organization, storage, and display of high resolution composite TMA images.

Influence of autologous arteriovenous fistula on the blood supply to the hand in very elderly hemodialyzed patients

INTRODUCTION

Arteriovenous fistula (AVF) creation for hemodialysis (HD) could predispose to local arterial insufficiency of the hand (steal syndrome). Patients with diabetes mellitus, peripheral arterial disease and elderly patients tend to have a higher risk of hand ischemia.

PURPOSE AND METHODS

To estimate the influence of AVF on the blood supply to the hands in the elderly population and to identify steal syndrome cases by non-invasive diagnostics (finger photoplethysmography (PPG), pulse volume recording (PVR), Doppler analysis and pulseoxymetry). The evaluation was carried out in 25 random patients (10 females, 15 males) >75 yrs of age (79.6 +/- 3.87 yrs), whose functioning autologous AVFs had been placed at least 1 month previously.

RESULTS

Mean PPG and PVR amplitudes did not differ in statistical analysis (p > 0.05) between hands with and without an AVF. One patient (4%) with end-to-side anastomosis was diagnosed with steal syndrome (typical manifestation confirmed in PPG, Doppler and pulseoxymetry). Two other patients with high brachio-cephalic anastomosis presented subclinical steal syndrome (only low PPG and PVR).

CONCLUSIONS

Even in the very elderly, AVF creation should be considered due to a lesser influence on the blood supply to the hands. Non-invasive diagnostics used by us seemed to be useful in identifying steal syndrome after AVF creation.

Matrix Metalloproteinase 26 Proteolysis of the NH2-Terminal Domain of the Estrogen Receptor β Correlates with the Survival of Breast Cancer Patients

Estrogens have many cellular functions, including their interactions with estrogen receptors alpha and beta (ERalpha and ERbeta). Earlier, we determined that the estrogen-ER complex stimulates the transcriptional activity of the matrix metalloproteinase 26 (MMP-26) gene promoter. We then determined that ERbeta is susceptible to MMP-26 proteolysis whereas ERalpha is resistant to the protease. MMP-26 targets the NH(2)-terminal region of ERbeta coding for the divergent NH(2)-terminal A/B domain that is responsible for the ligand-independent transactivation function. As a result, MMP-26 proteolysis generates the COOH-terminal fragments of ERbeta. Immunohistochemical analysis of tissue microarrays derived from 121 cancer patients corroborated these data and revealed an inverse correlation between the ERalpha-dependent expression of MMP-26 and the levels of the intact ERbeta in breast carcinomas. MMP-26 is not expressed in normal mammary epithelium. The levels of MMP-26 are strongly up-regulated in ductal carcinoma in situ (DCIS). In the course of further disease progression through stages I to III, the expression of MMP-26 decreases. In contrast to many tumor-promoting MMPs, the expression of MMP-26 in DCIS correlated with a longer patient survival. Our data suggest the existence of an MMP-26-mediated intracellular pathway that targets ERbeta and that MMP-26, a novel and valuable cancer marker, contributes favorably to the survival of the ERalpha/beta-positive cohort of breast cancer patients.

Critical function for SIP, a ubiquitin E3 ligase component of the beta-catenin degradation pathway, for thymocyte development and G1 checkpoint

Beta-catenin has been implicated in thymocyte development because of its function as a coactivator of Tcf/LEF-family transcription factors. Previously, we discovered a novel pathway for p53-induced beta-catenin degradation through a ubiquitin E3 ligase complex involving Siah1, SIP (CacyBP), Skp1, and Ebi. To gain insights into the physiological relevance of this new degradation pathway in vivo, we generated mutant mice lacking SIP. We demonstrate here that SIP-/- thymocytes have an impaired pre-TCR checkpoint with failure of TCRbeta gene rearrangement and increased apoptosis, resulting in reduced cellularity of the thymus. Moreover, the degradation of beta-catenin in response to DNA damage is significantly impaired in SIP-/- cells. SIP-/- embryonic fibroblasts show a growth-rate increase resulting from defects in G1 arrest. Thus, the beta-catenin degradation pathway mediated by SIP defines an essential checkpoint for thymocyte development and cell-cycle progression.

Outcome of Autogenous Fistula Construction in Hemodialyzed Patients Over 75 Years of Age

BACKGROUND

There are controversies regarding the feasibility of autogenous vascular access creation in elderly hemodialysis (HD) patients. The aim of this retrospective study was to evaluate the results of creating different types of autogenous arteriovenous fistulas (AVFs) in a consecutive series of HD patients over 75 years of age.

METHODS

The analysis was performed in 131 patients (65 females, 66 males, average age 79.1 +/- 3.6 years) in whom the creation of an autogenous AVF was considered within a 6-year period (February 1998 to February 2004). Among them, 26.7%were diabetics, 66.3% had hypertension, 30.7% were smokers, and 35.6% were obese. Patient survival and primary and secondary AVF patency were assessed.

RESULTS

The survival rates for patients were 94, 88, 66, and 45% at 6 months and at 1, 3, and 5 years, respectively. Successful autogenous AVF formation was finally achieved in 107 patients (81.6%): in 99 patients in the forearm and in 8in the upper arm. A Kaplan-Meier analysis showed primary AVF patency rates of: 74 +/- 4.3% (+/- SE) at 1 month; 70 +/- 4.7% at 6 months; 59 +/- 4.9% at 1 year; 59 +/- 4.9% at 2 years; 59+/- 4.9% at 3 years; 59 +/- 4.9% at 4 years, and 58 +/- 4.9% at 5 years. The secondary patency rates were: 95 +/- 2.0; 92 +/- 2.2; 84 +/- 3.3; 79 +/- 4.0; 72 +/- 4.3; 71 +/- 4.4, and 69 +/- 4.5% in the corresponding periods, respectively. All postoperative complications in 10 patients were treated surgically, if applicable, without endovascular techniques.

CONCLUSIONS

By exploiting all suitable types of autogenous AVF it is possible to establish the best form of vascular access even in the majority of elderly patients.

Cytoprotective gene bi-1 is required for intrinsic protection from endoplasmic reticulum stress and ischemia-reperfusion injury

Ischemia-reperfusion (IR) injury induces endoplasmic reticulum (ER) stress and cell death. Bax Inhibitor-1 (BI-1) is an evolutionarily conserved ER protein that suppresses cell death and that is abundantly expressed in both liver and kidney. We explored the role of BI-1 in protection from ER stress and IR injury by using bi-1 knockout mice, employing models of transient hepatic or renal artery occlusion. Compared to wild-type bi-1 mice, bi-1 knockout mice subjected to hepatic IR injury exhibited these characteristics: (i) increased histological injury; (ii) increased serum transaminases, indicative of more hepatocyte death; (iii) increased percentages of TUNEL-positive hepatocytes; (iv) greater elevations in caspase activity; and (v) more activation of ER stress proteins inositol-requiring enzyme 1 and activating transcription factor 6 and greater increases in expression of ER stress proteins C/EBP homologous protein and spliced XBP-1 protein. Moreover, hepatic IR injury induced elevations in bi-1 mRNA in wild-type liver, suggesting a need for bi-1 gene induction to limit tissue injury. Similar sensitization of kidney to ER stress and IR injury was observed in bi-1(-/-) mice. We conclude that bi-1 provides endogenous protection of liver and kidney from ER stress and IR injury. Analysis of components of the bi-1-dependent pathway for protection from IR injury may therefore reveal new strategies for organ preservation.

Prognostic significance of Bcl-6 protein expression in DLBCL treated with CHOP or R-CHOP: a prospective correlative study

Bcl-6 protein expression, a marker of germinal center origin, has been associated with a favorable prognosis in diffuse large B-cell lymphoma (DLBCL). To determine the prognostic significance of this marker when rituximab (R) was added to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy, we prospectively studied Bcl-6 protein expression by immunohistochemical staining of 199 paraffin-embedded specimens from patients enrolled in the US Intergroup phase 3 trial comparing R-CHOP to CHOP with or without maintenance R. In Bcl-6(-) patients, failure-free survival (FFS) and overall survival (OS) were prolonged for those treated with R-CHOP alone compared to CHOP alone (2-year FFS 76% versus 9%, P < .001; 2-year OS 79% versus 17%, P < .001). In contrast, no differences in FFS and OS were detected between treatment arms for Bcl-6(+) cases. In the multivariate analysis, treatment arm (CHOP versus R-CHOP) was the major determinant of both FFS (P < .001) and OS (P < .001) for the Bcl-6(-) subset, whereas the International Prognostic Index risk group was the only significant predictor of outcome among Bcl-6(+) cases. Bcl-2 protein expression was not predictive of outcome in either group. In this study, we observed a reduction in treatment failures and death with the addition of R to CHOP in Bcl-6(-) DLBCL cases only. Our finding that Bcl-6(+) cases did not benefit from the addition of R to CHOP requires independent confirmation.

Tumor-associated alterations in caspase-14 expression in epithelial malignancies

PURPOSE

Caspase-14 is unique among caspase family proteases in that its proteolytic processing has been principally associated with epithelial cell differentiation rather than apoptosis or inflammation. We investigated caspase-14 expression in several types of human epithelial malignancy by immunohistochemistry, correlating results with stage, histologic grade, and patient survival.

EXPERIMENTAL DESIGN

Tumor-associated alterations in caspase-14 expression were observed for cervical, ovarian, breast, gastric, and colon cancers.

RESULTS

In cervical (n = 445), ovarian (n = 91), and colon (n = 106) specimens, expression of caspase-14 was significantly reduced in cancers compared with normal epithelium. Decreases in caspase-14 immunopositivity correlated with the histologic progression of cervical cancer (P < 0.0001, ANOVA). In localized gastric cancers, caspase-14 immunostaining was significantly lower in poorly differentiated tumors compared with well-differentiated tumors (P = 0.02, Pearson's chi(2) analysis). Lower caspase-14 expression was associated with advanced clinical stage in ovarian cancer (P = 0.04, ANOVA) and with shorter overall survival among ovarian cancer patients with serous tumors (n = 62) in both univariate (P = 0.005) and multivariate (P = 0.03) analysis. Lower caspase-14 expression correlated with shorter overall survival among patients with T(3)N(0)M(0) stage gastric cancers (n = 94; P = 0.006, log-rank test). In contrast to cervical, ovarian, and colon cancers, caspase-14 expression was increased in ductal carcinoma in situ and invasive cancers compared with normal mammary epithelium (P = 0.001, t test).

CONCLUSIONS

The findings reveal tumor-specific alterations in caspase-14 expression and suggest that differences in its expression may define subsets of epithelial cancers with distinct clinical behaviors.

Analysis of apoptosis protein expression in early-stage colorectal cancer suggests opportunities for new prognostic biomarkers

PURPOSE

Although most stage II colon cancers are potentially curable by surgery alone, approximately 20% of patients relapse, suggesting a need for establishing prognostic markers that can identify patients who may benefit from adjuvant chemotherapy. We tested the hypothesis that differences in expression of apoptosis-regulating proteins account for differences in clinical outcome among patients with early-stage colorectal cancer.

EXPERIMENTAL DESIGN

Tissue microarray technology was employed to assay the expression of apoptosis-regulating proteins by immunohistochemistry in 106 archival stage II colorectal cancers, making correlations with disease-specific survival. The influence of microsatellite instability (MSI), tumor location (left versus right side), patient age, and gender was also examined.

RESULTS

Elevated expression of several apoptosis regulators significantly correlated with either shorter (cIAP2; TUCAN) or longer (Apaf1; Bcl-2) overall survival in univariate and multivariate analyses. These biomarkers retained prognostic significance when adjusting for MSI, tumor location, patient age, and gender. Moreover, certain combinations of apoptosis biomarkers were highly predictive of death risk from cancer. For example, 97% of patients with favorable tumor phenotype of cIAP2(low) plus TUCAN(low) were alive at 5 years compared with 60% of other patients (P = 0.00003). In contrast, only 37% of patients with adverse biomarkers (Apaf1(low) plus TUCAN(high)) survived compared with 83% of others at 5 years after diagnosis (P< 0.0001).

CONCLUSIONS

Immunohistochemical assays directed at detection of certain combinations of apoptosis proteins may provide prognostic information for patients with early-stage colorectal cancer, and therefore could help to identify patients who might benefit from adjuvant chemotherapy or who should be spared it.

Novel pan-neuronal Cre-transgenic line for conditional ablation of genes in the nervous system

Tissue-specific gene ablation is accomplished by combining conventional gene targeting approaches with site-specific recombinases such as the Cre/loxP system. Despite the use of a cardiac-specific rat myosin light chain II promoter, our transgenic line (CRE3) had little or no Cre expression in the heart; however, strong Cre activity was detected in the brain as early as gestation day E11.5. This was determined by several methods including crossing our mouse line with a lacZ indicator line (ROSA26). Transgenic Cre, in this mouse line, mediated DNA recombination of loxP-flanked genes selectively in neurons throughout the gray matter of the brain, cerebellum, spinal cord, as well as retina, dorsal, and sympathetic ganglia. Cre protein was also detected by immunohistochemistry exclusively in neurons, but not in other types of cells or tissues. Thus, our transgenic CRE3 mice provide pan-neuronal expression of CRE for carrying out conditional deletion of genes in neurons and their progenitors.

Synthetic Triterpenoids Cooperate with Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand to Induce Apoptosis of Breast Cancer Cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL or Apo2L) has been shown to induce apoptosis specifically in cancer cells while sparing normal tissues. Unfortunately not all cancer cells respond to TRAIL; therefore, TRAIL sensitizing agents are currently being explored. We have identified synthetic triterpenoids, including 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) and its derivative 1-(2-cyano-3,12-dioxooleana-1,9-dien-28-oyl) imidazole (CDDO-Im), which sensitize TRAIL-resistant cancer cells to TRAIL-mediated apoptosis. Here we show that TRAIL-treated T47D and MDA-MB-468 breast cancer cells fail to initiate detectable caspase-8 processing and, consequently, do not initiate TRAIL-mediated apoptosis. Concomitant treatment with CDDO or CDDO-Im reverses the TRAIL-resistant phenotype, promoting robust caspase-8 processing and induction of TRAIL-mediated apoptosis in vitro. The combination of triterpenoids and monoclonal anti-TRAIL receptor-1 (DR4) antibody also induces apoptosis of breast cancer cells in vitro. From a mechanistic standpoint, we show that CDDO and CDDO-Im down-regulate the antiapoptotic protein c-FLIP(L), and up-regulate cell surface TRAIL receptors DR4 and DR5. CDDO and CDDO-Im, when used in combination with TRAIL, have no adverse affect on cultured normal human mammary epithelial cells. Moreover, CDDO-Im and TRAIL are well tolerated in mice and the combination of CDDO-Im and TRAIL reduces tumor burden in vivo in an MDA-MB-468 tumor xenograft model. These data suggest that CDDO and CDDO-Im may be useful for selectively reversing the TRAIL-resistant phenotype in cancer but not normal cells.

TNF receptor-associated factor (TRAF) domain and Bcl-2 cooperate to induce small B cell lymphoma/chronic lymphocytic leukemia in transgenic mice

Transgenic mice overexpressing in B lymphocytes either Bcl-2 or a TNF receptor-associated factor (TRAF)2 mutant lacking the N-terminal RING and zinc finger domains located at the N terminus of the molecule (TRAF2DN), which mimics TRAF1, developed lymphadenopathy and splenomegaly due to polyclonal B cell expansion. Remarkably, TRAF2DN/Bcl-2 double-transgenic mice contained B cell populations similar to those observed in TRAF2DN mice. However, over time, they developed severe splenomegaly and lymphadenopathy, and most animals also developed leukemia, pleural effusion, and, in some cases, ascites associated with monoclonal and oligoclonal B cell neoplasms. The life span of TRAF2DN/Bcl-2 mice was markedly reduced compared with Bcl-2 and TRAF2DN single-transgenics or wild-type littermates. The expanded B cell population of TRAF2DN/Bcl-2 double-transgenic mice was primarily comprised of small/medium-size noncycling B220(M)/IgM(H)/IgD(L)/CD21(L)/CD23(NULL)/CD11b(+)/CD5+ cells that were Bcl-6-negative, consistent with a B-1 phenotype. The cells also expressed high levels of CD54 and other adhesion molecules. In vitro, these B cells showed comparable proliferation rates to those of wild-type counterparts but exhibited markedly increased survival and were resistant to apoptosis induced by chemotherapeutic agents and glucocorticoids. Histopathologic features were consistent with mouse small B cell lymphoma progressing to leukemia with many similarities to human chronic lymphocytic leukemia. Given that many human chronic lymphocytic leukemias overexpress TRAF1 and Bcl-2, our findings suggest that cooperation between Bcl-2 and TRAF pathways contributes to the development of this type of leukemia.

Early processing of Bid and caspase-6, -8, -10, -14 in the canine brain during cardiac arrest and resuscitation

A clinically relevant model of transient global brain ischemia involving cardiac arrest followed by resuscitation in dogs was utilized to study the expression and proteolytic processing of apoptosis-regulatory proteins. In the hippocampus, an increase in pro-apoptotic Bcl-2 family proteins Bcl-XS and Bak was detected, concomitant with proteolysis of Bcl-XL and Bcl-2, following ischemia-reperfusion injury. Also, biphasic cleavage of Bid was found in this region of the brain, with early generation of tBid-p11 within 10 min of cardiac arrest, followed by generation of tBid-p15 within 30-min reperfusion, consistent with activation of this pro-apoptotic protein. In addition, cardiac arrest and resuscitation induced early, reperfusion-dependent proteolytic processing of pro-caspase-6, -8, -10, and -14, which preceded caspase-3 activation. Immunohistochemical analysis using antibodies, which preferentially recognize processed caspase-3, -6, -8, and -10, provided evidence of time-dependent activation of these proteases in both neurons and glia in ischemia-sensitive regions of the brain. In conclusion, extremely rapid, cell-selective processing of apoptosis-regulatory proteins occurs in a clinically relevant model of ischemic brain injury caused by cardiac arrest and resuscitation. The early cleavage of Bid and rapid depletion of 32-kDa pro-caspase-14 from the canine hippocampus after induction of ischemia suggests the involvement of calpains in the processing of these proteins. Demonstration of in vitro cleavage of recombinant mouse caspase-14 by calpain I in the present study lends support to this hypothesis, further implicating cross-talk between different protease families in the pathophysiology of ischemic neural cell death.