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High levels of IL1β can result in chronic inflammation, which in turn can promote tumor growth and metastasis. Inhibition of IL1β could therefore be a promising therapeutic option in the treatment of cancer. Here, the effects of IL1β blockade induced by the mAbs canakinumab and gevokizumab were evaluated alone or in combination with docetaxel, anti–programmed cell death protein 1 (anti–PD-1), anti-VEGFα, and anti-TGFβ treatment in syngeneic and humanized mouse models of cancers of different origin. Canakinumab and gevokizumab did not show notable efficacy as single-agent therapies; however, IL1β blockade enhanced the effectiveness of docetaxel and anti–PD-1. Accompanying these effects, blockade of IL1β alone or in combination induced significant remodeling of the tumor microenvironment (TME), with decreased numbers of immune suppressive cells and increased tumor infiltration by dendritic cells (DC) and effector T cells. Further investigation revealed that cancer-associated fibroblasts (CAF) were the cell type most affected by treatment with canakinumab or gevokizumab in terms of change in gene expression. IL1β inhibition drove phenotypic changes in CAF populations, particularly those with the ability to influence immune cell recruitment. These results suggest that the observed remodeling of the TME following IL1β blockade may stem from changes in CAF populations. Overall, the results presented here support the potential use of IL1β inhibition in cancer treatment. Further exploration in ongoing clinical studies will help identify the best combination partners for different cancer types, cancer stages, and lines of treatment.

Supplementary tables S1-S5 and figures S1-S7

High levels of IL1β can result in chronic inflammation, which in turn can promote tumor growth and metastasis. Inhibition of IL1β could therefore be a promising therapeutic option in the treatment of cancer. Here, the effects of IL1β blockade induced by the mAbs canakinumab and gevokizumab were evaluated alone or in combination with docetaxel, anti–programmed cell death protein 1 (anti–PD-1), anti-VEGFα, and anti-TGFβ treatment in syngeneic and humanized mouse models of cancers of different origin. Canakinumab and gevokizumab did not show notable efficacy as single-agent therapies; however, IL1β blockade enhanced the effectiveness of docetaxel and anti–PD-1. Accompanying these effects, blockade of IL1β alone or in combination induced significant remodeling of the tumor microenvironment (TME), with decreased numbers of immune suppressive cells and increased tumor infiltration by dendritic cells (DC) and effector T cells. Further investigation revealed that cancer-associated fibroblasts (CAF) were the cell type most affected by treatment with canakinumab or gevokizumab in terms of change in gene expression. IL1β inhibition drove phenotypic changes in CAF populations, particularly those with the ability to influence immune cell recruitment. These results suggest that the observed remodeling of the TME following IL1β blockade may stem from changes in CAF populations. Overall, the results presented here support the potential use of IL1β inhibition in cancer treatment. Further exploration in ongoing clinical studies will help identify the best combination partners for different cancer types, cancer stages, and lines of treatment.

Purpose:The influence of the transcriptional and immunologic context of mutations on therapeutic outcomes with targeted therapy in cancer has not been well defined. BRAF V600E–mutant (BM) colorectal cancer comprises two main transcriptional subtypes, BM1 and BM2. We sought to determine the impact of BM subtype, as well as distinct biological features of those subtypes, on response to BRAF/MEK/EGFR inhibition in patients with colorectal cancer.Patients and Methods:Paired fresh tumor biopsies were acquired at baseline and on day 15 of treatment from all consenting patients with BM colorectal cancer enrolled in a phase II clinical trial of dabrafenib, trametinib, and panitumumab. For each sample, BM subtype, cell cycle, and immune gene signature expression were determined using RNA-sequencing (RNA-seq), and a Cox proportional hazards model was applied to determine association with progression-free survival (PFS).Results:Confirmed response rates, median PFS, and median overall survival (OS) were higher in BM1 subtype patients compared with BM2 subtype patients. Evaluation of immune contexture identified greater immune reactivity in BM1, whereas cell-cycle signatures were more highly expressed in BM2. A multivariate model of PFS incorporating BM subtype plus immune and cell-cycle signatures revealed that BM subtype encompasses the majority of the effect.Conclusions:BM subtype is significantly associated with the outcome of combination dabrafenib, trametinib, and panitumumab therapy and may serve as a standalone predictive biomarker beyond mutational status. Our findings support a more nuanced approach to targeted therapeutic decisions that incorporates assessment of transcriptional context.

Supplementary Data

Genetic inactivation of Notch signaling in CD4(-)CD8(-) double-negative (DN) thymocytes was previously shown to impair T cell receptor (TCR) gene rearrangement and to cause a partial block in CD4(+)CD8(+) double-positive (DP) thymocyte development in mice. In contrast, in vitro cultures suggested that Notch was absolutely required for the generation of DP thymocytes independent of pre-TCR expression and activity. To resolve the respective role of Notch and the pre-TCR, we inhibited Notch-mediated transcriptional activation in vivo with a green fluorescent protein-tagged dominant-negative Mastermind-like 1 (DNMAML) that allowed us to track single cells incapable of Notch signaling. DNMAML expression in DN cells led to decreased production of DP thymocytes but only to a modest decrease in intracellular TCRbeta expression. DNMAML attenuated the pre-TCR-associated increase in cell size and CD27 expression. TCRbeta or TCRalphabeta transgenes failed to rescue DNMAML-related defects. Intrathymic injections of DNMAML(-) or DNMAML(+) DN thymocytes revealed a complete DN/DP transition block, with production of DNMAML(+) DP thymocytes only from cells undergoing late Notch inactivation. These findings indicate that the Notch requirement during the beta-selection checkpoint in vivo is absolute and independent of the pre-TCR, and it depends on transcriptional activation by Notch via the CSL/RBP-J-MAML complex.

Human acute T-cell lymphoblastic leukemias and lymphomas (T-ALL) are commonly associated with gain-of-function mutations in Notch1 that contribute to T-ALL induction and maintenance. Starting from an expression-profiling screen, we identified c-myc as a direct target of Notch1 in Notch-dependent T-ALL cell lines, in which Notch accounts for the majority of c-myc expression. In functional assays, inhibitors of c-myc interfere with the progrowth effects of activated Notch1, and enforced expression of c-myc rescues multiple Notch1-dependent T-ALL cell lines from Notch withdrawal. The existence of a Notch1–c-myc signaling axis was bolstered further by experiments using c-myc-dependent murine T-ALL cells, which are rescued from withdrawal of c-myc by retroviral transduction of activated Notch1. This Notch1-mediated rescue is associated with the up-regulation of endogenous murine c-myc and its downstream transcriptional targets, and the acquisition of sensitivity to Notch pathway inhibitors. Additionally, we show that primary murine thymocytes at the DN3 stage of development depend on ligand-induced Notch signaling to maintain c-myc expression. Together, these data implicate c-myc as a developmentally regulated direct downstream target of Notch1 that contributes to the growth of T-ALL cells.

We have identified the heavy chain of ferritin as a developmentally regulated nuclear protein of embryonic chicken corneal epithelial cells. The nuclear ferritin is assembled into a supramolecular form that is indistinguishable from the cytoplasmic form of ferritin found in other cell types. Thus it most likely has iron-sequestering capabilities. Free iron, via the Fenton reaction, is known to exacerbate UV-induced and other oxidative damage to cellular components, including DNA. Since corneal epithelial cells are constantly exposed to UV light, we hypothesized that the nuclear ferritin might protect the DNA of these cells from free radical damage. To test this possibility, primary cultures of cells from corneal epithelium and other tissues were UV irradiated, and damage to DNA was detected by an in situ 3'-end labeling assay. Consistent with the hypothesis, corneal epithelial cells with nuclear ferritin had significantly less DNA breakage than the other cells types examined. However, when the expression of nuclear ferritin was inhibited the cells now became much more susceptible to UV-induced DNA damage. Since ferritin is normally cytoplasmic, corneal epithelial cells must have a mechanism that effects its nuclear localization. We have determined that this involves a nuclear transport molecule which binds to ferritin and carries it into the nucleus. This transporter, which we have termed ferritoid for its similarity to ferritin, has at least two domains. One domain is ferritin-like and is responsible for binding the ferritin; the other domain contains a nuclear localization signal that is responsible for effecting the nuclear transport. Therefore, it seems that corneal epithelial cells have evolved a novel, nuclear ferritin-based mechanism for protecting their DNA against UV damage. In addition, since ferritoid is structurally similar to ferritin, it may represent an example of a nuclear transporter that evolved from the molecule it transports (i.e., ferritin).

Ultraviolet (UV) light constitutes a major environmental hazard for all exposed tissues of the body. UV light can damage a variety of macromolecules—including alterations to DNA that are potentially carcinogenic. Much of the UV-induced damage to DNA is thought to result from the generation of reactive oxygen species (ROS) and the subsequent conversion of lowly-energetic ROS (e.g., H2O2) to highly energetic hydroxyl radicals. This occurs through the iron-mediated Fenton reaction. In skin, UV-induced damage to DNA is thought to be a major factor in the increasing incidence of epidermal cancers. However, corneal epithelial (CE) cells seem to be refractory to such damage—as primary cancers of these cells are extraordinarily rare—even though this tissue is transparent and constantly exposed to UV light. This suggests that CE cells have evolved a defense mechanism(s) that prevents damage to their DNA produced by both UV irradiation and ROS (e.g. H2O2). Studies in our laboratory suggest that one such mechanism involves having the iron-sequestering molecule ferritin in a nuclear localization—rather than cytoplasmic location it typically has in other cell types.

John M Millholland, Shuqiang Li, Cecilia A Fernandez, Anthony P ShuberPredictive Biosciences Inc, Lexington, MA, USAAbstract: Biological fluid-based noninvasive biomarker assays for monitoring and diagnosing disease are clinically powerful. A major technical hurdle for developing these assays is the requirement of high analytical sensitivity so that biomarkers present at very low levels can be consistently detected. In the case of biological fluid-based cancer diagnostic assays, sensitivities similar to those of tissue-based assays are difficult to achieve with DNA markers due to the high abundance of normal DNA background present in the sample. Here we describe a new urine-based assay that uses ultradeep sequencing technology to detect single mutant molecules of fibroblast growth factor receptor 3 (FGFR3) DNA that are indicative of bladder cancer. Detection of FGFR3 mutations in urine would provide clinicians with a noninvasive means of diagnosing early-stage bladder cancer. The single-molecule assay detects FGFR3 mutant DNA when present at as low as 0.02% of total urine DNA and results in 91% concordance with the frequency that FGFR3 mutations are detected in bladder cancer tumors, significantly improving diagnostic performance. To our knowledge, this is the first practical application of next-generation sequencing technology for noninvasive cancer diagnostics.Keywords: FGFR3, mutation, urine, single molecule, sequencing, bladder cancerCorrigendum for this paper has been published

Cecilia A Fernandez1, John M Millholland1, Ellen C Zwarthoff2, Adam S Feldman3, R Jeffrey Karnes4, Anthony P Shuber11Predictive Biosciences, Inc, Lexington, MA, USA; 2Erasmus Medical Center, Rotterdam, The Netherlands; 3Massachusetts General Hospital, Boston, MA, 4Mayo Clinic, Rochester, MN, USAPurpose: The authors recently reported the development of a noninvasive diagnostic assay using urinary matrix metalloproteinases (MMPs) as monitors of disease-free status and bladder cancer in high-risk populations. Using an approach called clinical intervention determining diagnostic (CIDD), they identified with high confidence those patients who could be excluded from additional intervention. To maximize performance, MMPs were combined with DNA-based markers and CIDD was applied to a population of patients undergoing monitoring for recurrence.Patients and methods: Urine samples were obtained from 323 patients, 48 of whom had a recurrence and 275 of whom did not have cancer upon cytoscopic evaluation. Twist1 and Nid2 methylation status was determined using methylation-specific polymerase chain reaction, FGFR3 mutational status by quantitative PCR, and MMP levels by enzyme-linked immunosorbent assay.Results: Using a combination of these DNA and protein markers, the authors identified with high confidence (97% negative predicted value) those patients who do not have cancer. Cutoffs were adjusted such that at 92% sensitivity, 51% of disease-free patients might be triaged from receiving further tests.Conclusion: The multi-analyte diagnostic readout assay described here is the first to combine protein and DNA biomarkers into one assay for optimal clinical performance. Using this approach, the detection of FGFR3 mutations and Twist1 and Nid2 methylation in the urine of patients undergoing bladder cancer recurrence screening increase the sensitivity and negative predictive value at an established MMP protein cutoff. This noninvasive urinary diagnostic assay could lead to the more efficient triage of patients undergoing recurrence monitoring.Keywords: matrix metalloproteinase, FGFR3, bladder cancer, diagnostics

Background As a noninvasive colorectal cancer (CRC) screening test, a multi-marker first generation stool DNA (sDNA V 1.0) test is superior to guaiac-based fecal occult blood tests. An improved sDNA assay (version 2), utilizing only two markers, hypermethylated vimentin gene (hV) and a two site DNA integrity assay (DY), demonstrated in a training set (phase 1a) an even higher sensitivity (88%) for CRC with a specificity of 82%. Aim To validate in an independent set of patients (phase 1b) the sensitivity and specificity of sDNA version 2 for CRC. Methods Forty-two patients with CRC and 241 subjects with normal colonoscopy (NC) provided stool samples, to which they immediately added DNA stabilizing buffer, and mailed their specimen to the laboratory. DNA was purified using gel-based capture, and analyzed for hV and DY using methods identical to those previously published. Results Using the same cutpoints as the 1a training set (N = 162; 40 CRCs, 122 normals), hV demonstrated a higher and DY a slightly lower sensitivity, for a combined sensitivity of hV + DY of 86%. Optimal cutpoints based on the combined phase 1a + 1b dataset (N = 445; 82 CRCs, 363 normals) yielded a CRC sensitivity of 83%. The vast majority of cancers were detected regardless of tumor stage, tumor location, or patient age. Assay specificity in the phase 1b dataset for hV, DY, and hV + DY was 82%, 85%, and 73%, respectively, using the phase 1a cutpoints. Optimal cutpoints based on the combined phase 1a + 1b dataset yield a specificity of 82%. Conclusions This study provides validation of a simplified, improved sDNA test that incorporates only two markers and that demonstrates high sensitivity (83%) and specificity (82%) for CRC. Test performance is highly reproducible in a large set of patients. The use of only two markers will make the test easier to perform, reduce the cost, and facilitate distribution to local laboratories.

Previously we reported that ferritin in corneal epithelial (CE) cells is a nuclear protein that protects DNA from UV damage. Since ferritin is normally cytoplasmic, in CE cells, a mechanism must exist that effects its nuclear localization. We have now determined that this involves a nuclear transport molecule we have termed ferritoid. Ferritoid is specific for CE cells and is developmentally regulated. Structurally, ferritoid contains multiple domains, including a functional SV40-type nuclear localization signal and a ferritin-like region of approximately 50% similarity to ferritin itself. This latter domain is likely responsible for the interaction between ferritoid and ferritin detected by co-immunoprecipitation analysis. To test functionally whether ferritoid is capable of transporting ferritin into the nucleus, we performed cotransfections of COS-1 cells with constructs for ferritoid and ferritin. Consistent with the proposed nuclear transport function for ferritoid, co-transfections with full-length constructs for ferritoid and ferritin resulted in a preferential nuclear localization of both molecules; this was not observed when the nuclear localization signal of ferritoid was deleted. Moreover, since ferritoid is structurally similar to ferritin, it may be an example of a nuclear transporter that evolved from the molecule it transports (ferritin).

The complete genomic sequence of the gene responsible for the predominant form of polycystic kidney disease, PKD1, was determined to provide a framework for understanding the biology and evolution of the gene, and to aid in the development of molecular diagnostics. The DNA sequence of a 54 kb interval immediately upstream of the poly(A) addition signal sequence of the PKD1 transcript was determined, and then analyzed using computer methods. A leucine-rich repeat (LRR) motif was identified within the resulting predicted protein sequence of the PKD1 gene. By analogy with other LRR-containing proteins, this may explain some of the disease-related renal alterations such as mislocalization of membrane protein constituents and changes in the extracellular matrix organization. Finally, comparison of the genomic sequence and the published partial cDNA sequence showed several differences between the two sequences. The most significant difference detected predicts a novel carboxy-terminus for the PKD1 gene product.

Methylation of the Twist1 gene has been linked to various cancers, including bladder cancer. We are developing a non-invasive diagnostic assay utilizing urinary protein and DNA biomarkers, including Twist1, as triage monitors in high-risk bladder cancer populations. Since final clinical assay performance is dependent on the optimal technical performance of each individual marker, we incorporated the use of chimeric PCR primers to establish PCR conditions for all DNA markers that would greatly simplify the process of optimizing PCR performance. Amplification of difficult DNA templates can involve significant optimization of PCR conditions, and is often complicated by mispriming and other non-specific amplification events. The chimeric primers we designed have a variable 3’ target-specific sequence, and a common 22 nucleotide 5’ sequence that is unrelated to any human DNA. The common 5’ sequence generates similar melting temperatures for all primers (Tm 68-72oC) that permits uniform PCR conditions regardless of the characteristics of the template specific sequence. In addition, the chimeric primers permit a higher annealing temperature, which minimizes non-specific PCR amplification. In the study described here, conventional methylation specific primers were designed against a highly methylated region of the Twist1 promoter with and without the 5’ chimeric DNA sequence, and PCR conditions were optimized for each primer pair. Performance was assessed using DNA isolated from 50 bladder cancer tissues. After bisulfite conversion, PCR amplifications were carried out using the Bio-Rad C1000 platform and subsequently analyzed by agarose gel electrophoresis. Using traditional primers, Twist1 sensitivity was comparable to previous reports (68%, Renard et al, 2010), whereas using the chimeric primers, sensitivity increased to 90%. Incorporation of chimeric primers greatly simplifies PCR optimization and permits the use of higher annealing temperatures, resulting in higher specificity. We have applied this method to the detection of Twist1 methylation in bladder cancer tissues and demonstrate significant improvement in performance, when compared to traditional, non-chimeric oligonucleotide primers. In addition, this primer modification can be applied to multiple assay formats and DNA targets to improve sensitivity for use in non-invasive diagnostic assays, where mutant DNA is expected to be limiting. 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 3870. doi:10.1158/1538-7445.AM2011-3870

Introduction The presence of blood in the urine (hematuria) is one of the hallmark symptoms of bladder cancer. Thus, the current best practice policy suggests that patients with hematuria undergo cystoscopic examination. However, hematuria can be present in healthy individuals as well as in individuals with various non-life threatening conditions such that a majority of patients with blood in the urine (∼95%) who are screened by cystoscopy do not have bladder cancer. In addition, recent studies have found that a majority of patients with hematuria are not referred on to a specialist for further invasive tests, despite the guidelines. This suggests that the prevalence of cancer in this population may be lower than 5%, making screening by cystoscopy inefficient and, in a large number of cases, unnecessary. We are developing a non-invasive diagnostic assay utilizing urinary protein and DNA biomarkers to triage those patients who do not have cancer from those who should go on to be existing invasive screening modalities. Methods Urine samples were obtained from 48 cancer patients and 256 patients who were evaluated for hematuria but who did not have cancer upon cystoscopic evaluation (Hem+/Cysto−). Twist1 and Nid2 methylation status was assessed using methylation-specific PCR primers and FGFR3 mutational status was determined by quantitative PCR. Matrix Metalloproteinases (MMPs) levels were determined by ELISA. Results Using a novel combination of these DNA and protein markers we identified with high confidence (99% negative predictive value) those patients who do not have cancer and who could be excluded from further testing. Cutoffs could be adjusted such that at 94% sensitivity, 65% of patients who do not have cancer could be excluded. Conclusions The Multi-Analyte Diagnostic Readout (MADR) assay described here combines the best performance characteristics of protein and DNA biomarkers into one assay for optimal clinical performance. Using this approach, the detection of FGFR3 mutations and Twist1 and Nid2 methylation in the urine of hematuria patients undergoing screening for bladder cancer effectively increases the sensitivity and negative predictive value at an established MMP protein cutoff. This non-invasive urinary diagnostic assay could lead to the more efficient triage of hematuria patients by identifying those patients who do not have cancer and could be excluded from receiving invasive procedures. 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 LB-313. doi:10.1158/1538-7445.AM2011-LB-313

Background: We have recently reported the development of a Multi-Analyte Diagnostic Readout (MADR) non-invasive assay using urinary Matrix Metalloproteinases (MMPs) and FGFR3 as triage monitors in high-risk bladder cancer populations. This concept combines the marker performance characteristics of protein and DNA biomarkers into one assay for optimal performance. Eight common FGFR3 mutations in 3 exons have been associated with bladder cancer. Analysis of mutational status for each single mutation required 8 amplification steps, which were costly and time consuming. We have now developed a real-time multiplexed FGFR3 assay, generating a cost-effective, clinically applicable assay for the detection of FGFR3 mutations in urine. Methods: Our approach involves a two-step PCR amplification process. The initial round generates exon specific PCR products, which are then used as template for real-time PCR mutation detection utilizing locked nucleic acid (LNA) oligonucleotides. These LNA suppress wild-type DNA amplification. To convert our existing FGFR3 assay to a multiplex format, primary amplifications of exons 7, 10, and 15 were combined into a single real-time PCR assay for exon specific amplification and DNA quantitation. The LNA-mediated mutation detection was then converted from 4 reactions to 2 duplex amplifications. All multiplex assays were carried out on the Roche LC 480 real-time PCR platform. Results: To validate the new the multiplex format, FGFR3 multiplex analysis was performed on DNA isolated from 50 Ta stage bladder tumors. FGFR3 mutations were detected in 90% (48/50) of the tumors. To directly compare performance with single mutation analysis, 40 urine samples previously analyzed using the singleplex format were again tested using the multiplex FGFR3 assay. 100% concordance was seen between the two assay formats. Conclusions: By multiplexing the FGFR3 mutation analysis we reduced the number of amplification steps, improving assay turnaround time and throughput, without compromising assay performance. The FGFR3 multiplex analysis provides a robust, cost-effective DNA assay that in combination with MMP protein analysis delivers a clinically applicable assay with optimal performance. 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 4161. doi:10.1158/1538-7445.AM2011-4161

ages of colonoscopies harbouring cancer and adenoma (at least 1, 2, 3, and any adenoma > 9 mm). Variables included in the models were gender, age and endoscopist. The oddsratios for each endoscopist were calculated by using the highest detection rate as reference. Results: There were 2068 included colonoscopies. The number of colonoscopies performed by each of the 21 endoscopists ranged from 37 to 167 examinations (median 98). The mean age of patients was 62.2 ± 7.2 yrs and 52.4% were men. CCR was detected in 221 (10.7%) and adenoma in 708 (34.2%) subjects, including 114 with at least 3 adenomas and 398 with adenoma > 9mm. Men had more cancers and adenomas (12.2% and 43.2%) than women (9% and 24.4%) (p=0.02 ; p 9mm), only age and gender were independent predictive factors. In multivariate analysis, odds-ratios ranged from 0.18 to 0.86 (median= 0.45) for at least one adenoma, and from 0.07 to 0.91 (median=0.37) for at least 2 adenomas, among endoscopists. The correlation between finding at least one adenoma of any size and at least one large adenoma was 0.68 (p

The deep space radiation environment is composed of both low-, and high-, LET radiation sources. High-LET radiation particles (HZE) are particularly dangerous because, by direction ionization of DNA, or radiolysis of water, they induce free radical formation that causes relatively non-repairable double strand breaks (DSB) and other complex damages to cellular DNA. The risk to flight crews exposed to HZE on extended duration voyages, such as the proposed Mars mission, has not been quantitated. Crew safety, and mission planning, dictate that such studies be done. We are examining the effects of low and high-LET radiation on human hematopoietic stem and progenitor cell function using normal human CD34+ cells obtained from consenting donors. Low-LET radiation was derived from a 137Cs source while HZE, primarily in the form of radioactive Fe, Ti, Si were generated by the Brookhaven National Laboratory’s (BNL) relativistic heavy ion collider-alternating gradient synchrotron (RHIC-AGS). Cells were prepared at UPENN, and shipped to BNL by overnight courier. The cells were then irradiated, with or without candidate radioprotectants, and aliquots of cells were then analyszed for DNA damage, and colony forming unit (CFU) function. Our initial studies indicated that human CD34+ cells demonstrated a dose dependent sensitivity to exposures as low as 15 cGy of both radiation types. The effects of HZE particles were more severe as shown by the dramatic decrease in assayable BFU-E, CFU-E, CFU-GM and CFU-GEMM assays. PMH treatment prior to irradiation, enhanced CFU formation by all lineages from 2–4 fold in the dose range of 15–50 cGy (137Cs) as compared to untreated cells. When doses increased to 70 cGy, PMH still displayed significant radioprotective effects in BFU-E and CFU-GEMM assay, as much as 2–3 fold, indicating some lineage specificity to its protective abilities. EUK-134 displayed significant radio-protection between 15-30 cGy as well and was slightly additive when combined with PMH. CFU were increased several fold compared to untreated controls in the dose range of 30-50 cGy of Fe. At 50 cGy, CFU-E, and CFU-GM were no longer protected. A decrease in the levels of phosphorylated histone H2A.X, a sensor of DSB, was observed in cells treated with PMH, and EUK-134, and correlated with the radioprotection observed. Immunochemical staining also documented an increase in repair proteins unique for DSB, such as Ku70/80, MRE-11 and Rad-50. Finally, the number of DNA ends labeled with dUTP-(FITC) terminal transferease enzyme was also increased. Altogether, these observations suggest that between 15–50 cGy, PMH and EUK-134 prevent DNA damage and DSB formation, thereby preserving CFU compared to untreated controls. Protective effects are lost when doses were greater than 50 cGy. We conclude that PMH and EUK-134 is effective against both low and high-LET, and that similar radioprotective mechanisms may be triggered in cells by each. Experiments to address the precise mechanisms of radioprotection by these compounds are ongoing in our labs, and will hopefully assist in the development of even more efficient radioprotective agents

The four mammalian Notch receptors play multiple roles in the hematolymphoid system. Notch1 is critical for the generation of hematopoietic stem cells (HSCs) during embryonic development and for commitment to the T cell lineage, while Notch2 regulates marginal zone B cell development. In addition, important roles for Notch are starting to be identified in peripheral T cells, in which all four Notch family members are upregulated upon T cell activation. Canonical Notch signaling involves proteolytic cleavage of Notch receptors and translocation of intracellular Notch (ICN) to the nucleus where it interacts with the transcription factor CSL/RBP-J and recruits Mastermind-like proteins (MAMLs) for transcriptional activation. By inhibiting Notch1 and Notch2-dependent developmental decisions with a dominant negative mutant of MAML1 (DNMAML1), we have previously demonstrated that MAMLs critically regulate Notch signaling in vivo (Maillard et al., Blood 2004). However, it is unclear if Notch3 and Notch4 are equally dependent on the activity of MAMLs in vivo, and if DNMAML1 can thus be used as a true pan-Notch inhibitor. To address this question, we used a modified fetal thymic organ culture (FTOC) system and Notch-mediated T lineage commitment as a readout for Notch function. Fetal liver cells (FLCs) were transduced with retroviruses expressing ICN1, ICN3 or ICN4 and a retrovirus expressing DNMAML1. Irradiated fetal thymic lobes were reconstituted with transduced FLCs and cultured in the presence of gamma secretase inhibitors to inhibit the activation of endogenous Notch receptors. In this manner the effect of a specific ICN could be evaluated in the absence of endogenous Notch signals. Gamma secretase inhibitors resulted in a profound block in T cell development and in the generation of intrathymic B cells, consistent with Notch1 inhibition. ICN1, ICN3 and ICN4 were all able to rescue commitment to the T cell lineage and to block B cell development, indicating that each ICN can deliver appropriate signals for T lineage commitment in the absence of endogenous Notch1 signaling. In cells doubly transduced with specific ICNs and DNMAML1, the rescuing effect of ICN1, ICN3 or ICN4 was blocked, leading to the generation of B cells. In this competitive situation, DNMAML1 only partially inhibited ICN1, the most potent of all four Notch family members, but it was able to completely inhibit ICN3 and ICN4. We conclude that DNMAML1 can efficiently inhibit Notch3 and Notch4 in vivo. The results validate the use of DNMAML1 as a bona fide pan-Notch inhibitor in multiple settings, including studying the role of Notch in HSCs and peripheral T cells.