Bacteriostatic and Antibiofilm Efficacy of a Nisin Z Solution against Co-Cultures of Staphylococcus aureus and Pseudomonas aeruginosa from Diabetic Foot Infections

Diabetes mellitus (DM) patients frequently develop diabetic foot ulcers (DFU) which are generally infected by a community of microorganisms, mainly Staphylococcus aureus and Pseudomonas aeruginosa. These bacteria exhibit a multi-drug resistance profile and biofilm-forming ability which represent a hurdle in the treatment of diabetic foot infections (DFI). We aimed to evaluate the potential of Nisin Z, an antimicrobial peptide (AMP), as an alternative treatment for severe DFI. Nisin Z shows antibacterial activity against Gram-positive and Gram-negative bacteria and an increased antibacterial effect against Gram-negatives when added to EDTA. As such, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Biofilm Inhibitory Concentration (MBIC), and Minimum Biofilm Eradication Concentration (MBEC) were determined for Nisin Z, Nisin Z + EDTA (0.4%), and Nisin Z + EDTA incorporated into guar gum, in order to test its efficacy against S. aureus and P. aeruginosa isolated from the same DFU. Results showed that Nisin Z added to the chelation agent EDTA displayed higher antibacterial and bacteriostatic efficacy against mono and dual co-cultures of S. aureus and P. aeruginosa, and higher antibiofilm efficiency against monocultures. Nisin Z was moderately cytotoxic at 200 µg/mL. Prospect in vivo studies are needed to confirm the potential of Nisin Z supplemented with EDTA to be used as a complement to conventional antibiotic therapy for severe DFI.

Immunolocalization of Notch Signaling in Mouse Preimplantation Embryos

The Notch signaling pathway is an important determinant of cell diversity and identity in most developing embryonic tissues. The pathway components are expressed dynamically, and their function is critical for embryonic survival.This protocol addresses the immunolocalization of Notch pathway components by confocal microscopy.

Influence of Storage on the Antimicrobial and Cytotoxic Activities of a Nisin-biogel with Potential to be Applied to Diabetic Foot Infections Treatment

Staphylococcus aureus is the most prevalent pathogen in diabetic foot infections (DFIs). In addition to its ability to express several virulence factors, including the formation of recalcitrant biofilms, S. aureus is also becoming increasingly resistant to most antibiotics used in clinical practice. The search for alternative treatment strategies for DFI is urgently needed. Antimicrobial peptides (AMPs), namely, nisin, are emerging as potential new therapeutics for managing DFIs. Our team has developed a nisin-guar gum biogel to be applied to DFIs. In this study, to confirm its future in vivo applicability, we evaluated the influence of four storage temperatures (−20 °C, 4 °C, 22 °C, and 37 °C) during a 24 months storage period on its antimicrobial activity towards DFI S. aureus, and its cytotoxicity, to a human keratinocyte cell line. When stored at temperatures below 22 °C, the biogel antimicrobial activity was not significantly influenced by storage duration or temperature. Moreover, nisin incorporated within the guar gum biogel exhibited no significant levels of cytotoxicity on human keratinocyte cells, confirming its potential for DFIs therapeutics. In conclusion, results confirm that the nisin-biogel is a potential candidate to be used as an alternative or complement compound for conventional DFI therapeutics.

Bioconjugation with Maleimides: A Useful Tool for Chemical Biology

Maleimide chemistry stands out in the bioconjugation toolbox by virtue of its synthetic accessibility, excellent reactivity, and practicability. The second-generation of clinically approved antibody-drug conjugates (ADC) and much of the current ADC pipeline in clinical trials contain the maleimide linkage. However, thiosuccinimide linkages are now known to be less robust than once thought, and ergo, are correlated with suboptimal pharmacodynamics, pharmacokinetics, and safety profiles in some ADC constructs. Rational design of novel generations of maleimides and maleimide-type reagents have been reported to address the shortcomings of classical maleimides, allowing for the formation of robust bioconjugate linkages. This review highlights the main strategies for rational reagent design that have allowed irreversible bioconjugations in cysteines, reversible labelling strategies and disulfide re-bridging.

miR-21 ablation and obeticholic acid ameliorate nonalcoholic steatohepatitis in mice

This corrects the article DOI: 10.1038/cddis.2017.172.

miR-21 ablation and obeticholic acid ameliorate nonalcoholic steatohepatitis in mice

microRNAs were recently suggested to contribute to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), a disease lacking specific pharmacological treatments. In that regard, nuclear receptors are arising as key molecular targets for the treatment of nonalcoholic steatohepatitis (NASH). Here we show that, in a typical model of NASH-associated liver damage, microRNA-21 (miR-21) ablation results in a progressive decrease in steatosis, inflammation and lipoapoptosis, with impairment of fibrosis. In a complementary fast food (FF) diet NASH model, mimicking features of the metabolic syndrome, miR-21 levels increase in both liver and muscle, concomitantly with decreased expression of peroxisome proliferator-activated receptor α (PPARα), a key miR-21 target. Strikingly, miR-21 knockout mice fed the FF diet supplemented with farnesoid X receptor (FXR) agonist obeticholic acid (OCA) display minimal steatosis, inflammation, oxidative stress and cholesterol accumulation. In addition, lipoprotein metabolism was restored, including decreased fatty acid uptake and polyunsaturation, and liver and muscle insulin sensitivity fully reinstated. Finally, the miR-21/PPARα axis was found amplified in liver and muscle biopsies, and in serum, of NAFLD patients, co-substantiating its role in the development of the metabolic syndrome. By unveiling that miR-21 abrogation, together with FXR activation by OCA, significantly improves whole body metabolic parameters in NASH, our results highlight the therapeutic potential of nuclear receptor multi-targeting therapies for NAFLD.

Endothelial Dll4 overexpression reduces vascular response and inhibits tumor growth and metastasization in vivo

BACKGROUND

The inhibition of Delta-like 4 (Dll4)/Notch signaling has been shown to result in excessive, nonfunctional vessel proliferation and significant tumor growth suppression. However, safety concerns emerged with the identification of side effects resulting from chronic Dll4/Notch blockade. Alternatively, we explored the endothelial Dll4 overexpression using different mouse tumor models.

METHODS

We used a transgenic mouse model of endothelial-specific Dll4 overexpression, previously produced. Growth kinetics and vascular histopathology of several types of solid tumors was evaluated, namely Lewis Lung Carcinoma xenografts, chemically-induced skin papillomas and RIP1-Tag2 insulinomas.

RESULTS

We found that increased Dll4/Notch signaling reduces tumor growth by reducing vascular endothelial growth factor (VEGF)-induced endothelial proliferation, tumor vessel density and overall tumor blood supply. In addition, Dll4 overexpression consistently improved tumor vascular maturation and functionality, as indicated by increased vessel calibers, enhanced mural cell recruitment and increased network perfusion. Importantly, the tumor vessel normalization is not more effective than restricted vessel proliferation, but was found to prevent metastasis formation and allow for increased delivery to the tumor of concomitant chemotherapy, improving its efficacy.

CONCLUSIONS

By reducing endothelial sensitivity to VEGF, these results imply that Dll4/Notch stimulation in tumor microenvironment could be beneficial to solid cancer patient treatment by reducing primary tumor size, improving tumor drug delivery and reducing metastization. Endothelial specific Dll4 overexpression thus appears as a promising anti-angiogenic modality that might improve cancer control.

Delta-like 4/Notch signaling promotes Apc Min/+ tumor initiation through angiogenic and non-angiogenic related mechanisms

Background

Delta like 4 (Dll4)/Notch signaling is a key regulator of tumor angiogenesis. Additionally, the role of Dll4 has been studied on tumor stem cells. However, as these cells are implicated in tumor angiogenesis, it is conceivable that the effect of Dll4 on these cells may be a consequence of its angiogenic function. Our aim was to evaluate the expression and dissect the functions of Dll4 in the Apc^Min/+ model of colorectal cancer.

Methods

We evaluated the protein expression pattern of Dll4 and other Notch members in the Apc^Min/+ tumors relatively to the normal gut and compared endothelial-specific with ubiquitous Dll4 knockout mice on an Apc^Min/+ background.

Results

All Notch pathway members were present in the normal small and large intestine and in the adenomas of the same regions. Dll4, all Notch receptors and Hes1 expression seemed upregulated in the tumors, with some regional differences. The same members and Hes5, instead of Hes1, presented ectopic expression in the tumor parenchyma. Dll4 expression was most pronounced in the tumor cells but it was also present in the tumor blood vessels and in other stromal cells. Ubiquitous and endothelial-specific Dll4 deletion led to an equivalent reduction of tumor growth because of a similarly marked tumoral angiogenic phenotype promoting non-productive vasculature and consequently hypoxia and apoptosis. The ubiquitous Dll4 inhibition led to a stronger decrease of tumor multiplicity than the endothelial-specific deletion by further reducing tumor proliferation and tumor stem cell density through upregulation of the cyclin-dependent kinase inhibitors 1C and 1B and downregulation of Myc, Cyclin D1 and D2 independently of β-catenin activation. This phenotype was associated to the observed increased epithelial differentiation deviated towards the secretory lineages by Atoh1 and Klf4 upregulation only in the ubiquitous Dll4 mutants.

Conclusions

Dll4 seems to promote Apc^Min/+ tumorigenesis through both angiogenic and non-angiogenic related mechanisms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-3036-0) contains supplementary material, which is available to authorized users.

Endothelial Jagged1 promotes solid tumor growth through both pro-angiogenic and angiocrine functions

Angiogenesis is an essential process required for tumor growth and progression. The Notch signaling pathway has been identified as a key regulator of the neo-angiogenic process. Jagged-1 (Jag1) is a Notch ligand required for embryonic and retinal vascular development, which direct contribution to the regulation of tumor angiogenesis remains to be fully characterized.

The current study addresses the role of endothelial Jagged1-mediated Notch signaling in the context of tumoral angiogenesis in two different mouse tumor models: subcutaneous Lewis Lung Carcinoma (LLC) tumor transplants and the autochthonous Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP).

The role of endothelial Jagged1 in tumor growth and neo-angiogenesis was investigated with endothelial-specific Jag1 gain- and loss-of-function mouse mutants (eJag1OE and eJag1cKO). By modulating levels of endothelial Jag1, we observed that this ligand regulates tumor vessel density, branching, and perivascular maturation, thus affecting tumor vascular perfusion. The pro-angiogenic function is exerted by its ability to positively regulate levels of Vegfr-2 while negatively regulating Vegfr-1. Additionally, endothelial Jagged1 appears to exert an angiocrine function possibly by activating Notch3/Hey1 in tumor cells, promoting proliferation, survival and epithelial-to-mesenchymal transition (EMT), potentiating tumor development. These findings provide valuable mechanistic insights into the role of endothelial Jagged1 in promoting solid tumor development and support the notion that it may constitute a promising target for cancer therapy.

Notch signaling dynamics in the adult healthy prostate and in prostatic tumor development

BACKGROUND

The Notch signaling pathway has been implicated in prostate development, maintenance and tumorigenesis by its key role in cell-fate determination, differentiation and proliferation. Therefore, we proposed to analyze Notch family members transcription and expression, including ligands (Dll1, 3, 4 and Jagged1 and 2), receptors (Notch1-4) and effectors (Hes1, 2, 5 and Hey1, 2, L), in both normal and tumor bearing mouse prostates to better understand the dynamics of Notch signaling in prostate tumorigenesis.

METHODS

Wild type mice and transgenic adenocarcinoma of the mouse prostate model (TRAMP) mice were sacrificed at 18, 24 or 30 weeks of age and the prostates collected and processed for either whole prostate or prostate cell specific populations mRNA analysis and for protein expression analysis by immunohistochemistry and immunofluorescence.

RESULTS

We observed that Dll1 and Dll4 are expressed in the luminal compartment of the mouse healthy prostate, whereas Jagged2 expression is restricted to the basal and stromal compartment. Additionally, Notch2 and Notch4 are normally expressed in the prostate luminal compartment while Notch2 and Notch3 are also expressed in the stromal layer of the healthy prostate. As prostate tumor development takes place, there is up-regulation of Notch components. Particularly, the prostate tumor lesions have increased expression of Jagged1 and 2, of Notch3 and of Hey1. We have also detected the presence of activated Notch3 in prostatic tumors that co-express Jagged1 and ultimately the Hey1 effector.

CONCLUSIONS

Taken together our results point out the Notch axis Jagged1-2/Notch3/Hey1 to be important for prostate tumor development and worthy of additional functional studies and validation in human clinical disease.

Incomplete Dll4/Notch signaling inhibition promotes functional angiogenesis supporting the growth of skin papillomas

BACKGROUND

In invasive malignancies, Dll4/Notch signaling inhibition enhances non-functional vessel proliferation and limits tumor growth by reducing its blood perfusion.

METHODS

To assess the effects of targeted Dll4 allelic deletion in the incipient stages of tumor pathogenesis, we chemically induced skin papillomas in wild-type and Dll4 (+/-) littermates, and compared tumor growth, their histological features, vascularization and the expression of angiogenesis-related molecules.

RESULTS

We observed that Dll4 down-regulation promotes productive angiogenesis, although with less mature vessels, in chemically-induced pre-cancerous skin papillomas stimulating their growth. The increase in endothelial activation was associated with an increase in the VEGFR2 to VEGFR1 ratio, which neutralized the tumor-suppressive effect of VEGFR-targeting sorafenib. Thus, in early papillomas, lower levels of Dll4 increase vascularization through raised VEGFR2 levels, enhancing sensitivity to endogenous levels of VEGF, promoting functional angiogenesis and tumor growth.

CONCLUSION

Tumor promoting effect of low-dosage inhibition needs to be considered when implementing Dll4 targeting therapies.

Dynamics of Notch signalling in the mouse oviduct and uterus during the oestrous cycle

The oviduct and uterus undergo extensive cellular remodelling during the oestrous cycle, requiring finely tuned intercellular communication. Notch is an evolutionarily conserved cell signalling pathway implicated in cell fate decisions in several tissues. In the present study we evaluated the quantitative real-time polymerase chain reaction (real-time qPCR) and expression (immunohistochemistry) patterns of Notch components (Notch1-4, Delta-like 1 (Dll1), Delta-like 4 (Dll4), Jagged1-2) and effector (hairy/enhancer of split (Hes) 1-2, Hes5 and Notch-Regulated Ankyrin Repeat-Containing Protein (Nrarp)) genes in the mouse oviduct and uterus throughout the oestrous cycle. Notch genes are differentially transcribed and expressed in the mouse oviduct and uterus throughout the oestrous cycle. The correlated transcription levels of Notch components and effector genes, and the nuclear detection of Notch effector proteins, indicate that Notch signalling is active. The correlation between transcription levels of Notch genes and progesterone concentrations, and the association between expression of Notch proteins and progesterone receptor (PR) activation, indicate direct progesterone regulation of Notch signalling. The expression patterns of Notch proteins are spatially and temporally specific, resulting in unique expression combinations of Notch receptor, ligand and effector genes in the oviduct luminal epithelium, uterus luminal and glandular epithelia and uterine stroma throughout the oestrous cycle. Together, the results of the present study imply a regulatory role for Notch signalling in oviduct and uterine cellular remodelling occurring throughout the oestrous cycle.

Notch1 is pan-endothelial at the onset of flow and regulated by flow

Arteriovenous differentiation is a key event during vascular development and hemodynamic forces play an important role. Arteriovenous gene expression is present before the onset of flow, however it remains plastic and flow can alter arteriovenous identity. Notch signaling is especially important in the genetic determination of arteriovenous identity. Nevertheless, the effect of the onset of circulation on Notch expression and signaling has not been studied. The aim of this study is therefore to investigate the interaction of Notch1 signaling and hemodynamic forces during early vascular development. We find that the onset of Notch1 expression coincides with the onset of flow, and that expression is pan-endothelial at the onset of circulation in mouse embryos and only becomes arterial-specific after remodeling has occurred. When we ablate flow in the early embryo, endothelial cells fail to express Notch1. We show that low and disturbed flow patterns upregulate Notch1 expression in endothelial cells in vitro, but that higher shear stress levels do not (≥10 dynes/cm²). Using siRNA, we knocked down Notch1 to investigate the role of Notch1 in mechanotransduction. When we applied shear stress levels similar to those found in embryonic arteries, we found an upregulation of Klf2, Dll1, Dll4, Jag1, Hey1, Nrp1 and CoupTFII but that only Dll4, Hey1, Nrp1 and EphB4 required Notch1 for flow-induced expression. Our results therefore indicate that Notch1 can modulate mechanotransduction but is not a critical mediator of the process since many genes mechanotransduce normally in the absence of Notch1, including genes involved in arteriovenous differentiation.

Endothelial Jagged1 antagonizes Dll4 regulation of endothelial branching and promotes vascular maturation downstream of Dll4/Notch1

OBJECTIVE

Notch signaling controls cardiovascular development and has been associated with several pathological conditions. Among its ligands, Jagged1 and Dll4 were shown to have opposing effects in developmental angiogenesis, but the underlying mechanism and the role of Jagged1/Notch signaling in adult angiogenesis remain incompletely understood. The current study addresses the importance of endothelial Jagged1-mediated Notch signaling in the context of adult physiological angiogenesis and the interactions of Jagged1 and Dll4 on angiogenic response and vascular maturation processes.

APPROACH AND RESULTS

The role of endothelial Jagged1 in wound healing kinetics and angiogenesis was investigated with endothelial-specific Jag1 gain-of-function and loss-of-function mouse mutants (eJag1OE and eJag1cKO). To study the interactions between the 2 Notch ligands, genetic mouse models were combined with pharmacological inhibition of Dll4 or Jagged1, respectively. Jagged1 overexpression in endothelial cells increased vessel density, maturation, and perfusion, thus accelerating wound healing. The opposite effect was seen in eJag1cKO animals. Interestingly, Dll4 blockade in these animals led to an increase in vascular density but induced a greater decrease in perivascular cell coverage. However, Jagged1 inhibition in Dll4 gain-of-function (eDll4OE) mutants, with reduced angiogenesis, further diminished angiogenic growth and hampered perivascular cell coverage. Our findings suggest that as Dll4 blocks endothelial activation through Notch1 signaling, it also induces Jagged1 expression. Jagged1 then blocks Dll4 signaling through Notch1, allowing endothelial activation by vascular endothelial growth factor and endothelial layer growth. Jagged1 also initiates maturation of the newly formed vessels, possibly by binding and activating endothelial Notch4. Importantly, mice administered with a Notch4 agonistic antibody mimicked the mural cell phenotype of eJag1OE mutants without affecting angiogenic growth, which is thought to be Notch1 dependent.

CONCLUSIONS

Endothelial Jagged1 is likely to operate downstream of Dll4/Notch1 signaling to activate Notch4 and regulate vascular maturation. Thus, Jagged1 not only counteracts Dll4/Notch in the endothelium but also generates a balance between angiogenic growth and maturation processes in vivo.

Differential expression of Notch component and effector genes during ovarian follicle and corpus luteum development during the oestrous cycle

Ovarian dynamics throughout the female oestrous cycle (EC) are characterised by cyclical follicle and corpus luteum (CL) development. These events are tightly regulated, involving extensive cell-to-cell communication. Notch is an evolutionarily well conserved cell-signalling pathway implicated in cell-fate decisions in several tissues. Here, we evaluated the extra-vascular expression patterns of Notch component and effector genes during follicle and CL development throughout the EC. Five mature CD1 female mice were killed at each EC stage. Blood samples were collected for progesterone measurement, ovaries were processed for immunohistochemistry and expression patterns of Notch components (Notch1, 2 and 3, Jagged1 and Delta-like1 and 4) and effectors (Hes1, Hes2 and Hes5) were characterised. Nuclear detection of Notch effectors indicates that Notch signalling is active in the ovary. Notch components and effectors are differentially expressed during follicle and CL development throughout the EC. The spatial and temporal specific expression patterns are associated with follicle growth, selection and ovulation or atresia and CL development and regression.

In vivo notch signaling blockade induces abnormal spermatogenesis in the mouse

In a previous study we identified active Notch signaling in key cellular events occurring at adult spermatogenesis. In this study, we evaluated the function of Notch signaling in spermatogenesis through the effects of in vivo Notch blockade. Adult CD1 male mice were either submitted to a long term DAPT (?-secretase inhibitor) or vehicle treatment. Treatment duration was designed to attain one half the time (25 days) or the time (43 days) required to accomplish a complete cycle of spermatogenesis. Blockade of Notch signaling was depicted from decreased transcription of Notch effector genes. Notch signaling blockade disrupted the expression patterns of Notch components in the testis, induced male germ cell fate aberrations, and significantly increased germ cell apoptosis, mainly in the last stages of the spermatogenic cycle, and epididymis spermatozoa morphological defects. These effects were more pronounced following the 43 day than the 25 day DAPT treatment schedule. These results indicate a relevant regulatory role of Notch signaling in mammalian spermatogenesis.

Dynamics of Notch pathway expression during mouse testis post-natal development and along the spermatogenic cycle

The transcription and expression patterns of Notch pathway components (Notch 1–3, Delta1 and 4, Jagged1) and effectors (Hes1, Hes2, Hes5 and Nrarp) were evaluated (through RT-PCR and IHC) in the mouse testis at key moments of post-natal development, and along the adult spermatogenic cycle. Notch pathway components and effectors are transcribed in the testis and expressed in germ, Sertoli and Leydig cells, and each Notch component shows a specific cell-type and time-window expression pattern. This expression at key testis developmental events prompt for a role of Notch signaling in pre-pubertal spermatogonia quiescence, onset of spermatogenesis, and regulation of the spermatogenic cycle.

Dll4-Notch signaling determines the formation of native arterial collateral networks and arterial function in mouse ischemia models

Arteriogenesis requires growth of pre-existing arteriolar collateral networks and determines clinical outcome in arterial occlusive diseases. Factors responsible for the development of arteriolar collateral networks are poorly understood. The Notch ligand Delta-like 4 (Dll4) promotes arterial differentiation and restricts vessel branching. We hypothesized that Dll4 may act as a genetic determinant of collateral arterial networks and functional recovery in stroke and hind limb ischemia models in mice. Genetic loss- and gain-of-function approaches in mice showed that Dll4-Notch signaling restricts pial collateral artery formation by modulating arterial branching morphogenesis during embryogenesis. Adult Dll4(+/-) mice showed increased pial collateral numbers, but stroke volume upon middle cerebral artery occlusion was not reduced compared with wild-type littermates. Likewise, Dll4(+/-) mice showed reduced blood flow conductance after femoral artery occlusion, and, despite markedly increased angiogenesis, tissue ischemia was more severe. In peripheral arteries, loss of Dll4 adversely affected excitation-contraction coupling in arterial smooth muscle in response to vasopressor agents and arterial vessel wall adaption in response to increases in blood flow, collectively contributing to reduced flow reserve. We conclude that Dll4-Notch signaling modulates native collateral formation by acting on vascular branching morphogenesis during embryogenesis. Dll4 furthermore affects tissue perfusion by acting on arterial function and structure. Loss of Dll4 stimulates collateral formation and angiogenesis, but in the context of ischemic diseases such beneficial effects are overruled by adverse functional changes, demonstrating that ischemic recovery is not solely determined by collateral number but rather by vessel functionality.

Abstract 540: Role of EphB4-EphrinB2 as novel target in Her2 positive breast cancer

Background: Her2 amplification drives tumor growth in 20% of breast cancers. Her2 targeted therapies have improved survival, but eventual failure occurs and additional targeted therapies to overcome resistance are needed. EphB4 and EphrinB2 receptor kinase -ligand pair is induced in Her2 positive tumors and is a novel target.

Methods: Her2 positive tumor cell lines and Her2 transgenic mouse lines were studied for expression of EphB4-EphrinB2. The role of EphB4-EphrinB2 was examined by knock down with shRNA. In vivo tumor xenograft studies with Her2 positive cell lines resistant or sensitive to Her2 targeted therapy, and Her2 transgenic mouse were treated with soluble decoy receptor (soluble EphB4-Albumin fusion protein). Tumor response and activation status of Her2 were examined.

Results: EphB4 and EphrinB2 are induced in Her2 positive tumor cell lines with further induction in trastuzumab (Herceptin) resistant tumor lines. Knock down of EphB4 with shRNA reduced the cell viability by nearly 80% compared to control shRNA. In vivo studies with sEphB4-Albumin also reduced the tumor growth by 70-80% accompanied by the reduction in pHer2 and pEGFR. No effect was seen on pHer3. Combination with lapatinib and sEphB4-Albumin was additive. sEphB4-Albumin inhibited tumor growth in Her2 resistant tumor cell lines by 56%.

Conclusion: EphB4 and EphrinB2 are induced by Herceptin sensitive and resistant Her2 positive tumors. EphB4 provides survival advantage to Her2 positive trastuzumab sensitive and resistant tumors. sEphB4-Albumin inhibits tumor growth as single agent in both trastuzumab sensitive and resistant tumors. sEphB4-Albumin is currently in the clinical development and thus worthy of investigation in Her2 positive cancers.

Citation Format: A. Duarte, J. Quaresma, A. Trindade, P. Tripathy, X. Liu, V. Krasnoperov, R. Liu, P.S. Gill. Role of EphB4-EphrinB2 as novel target in Her2 positive breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 540. doi:10.1158/1538-7445.AM2013-540

Low-dosage inhibition of Dll4 signaling promotes wound healing by inducing functional neo-angiogenesis

Recent findings regarding Dll4 function in physiological and pathological conditions indicate that this Notch ligand may constitute an important therapeutic target. Dll4 appears to be a major anti-angiogenic agent, occupying a central role in various angiogenic pathways. The first trials of anti-Dll4 therapy in mice demonstrated a paradoxical effect, as it reduced tumor perfusion and growth despite leading to an increase in vascular density. This is seen as the result of insufficient maturation of the newly formed vasculature causing a circulatory defect and increased tumor hypoxia. As Dll4 function is known to be closely dependent on expression levels, we envisioned that the therapeutic anti-Dll4 dosage could be modulated to result in the increase of adequately functional blood vessels. This would be useful in conditions where vascular function is a limiting factor for recovery, like wound healing and tissue hypoxia, especially in diabetic patients. Our experimental results in mice confirmed this possibility, revealing that low dosage inhibition of Dll4/Notch signaling causes improved vascular function and accelerated wound healing.

Abstract LB-285: Blocking Dll4/Notch signaling inhibits development of chronic colitis-associated colorectal cancer in mice

Colorectal cancer (CRC) is one of the most frequent cancers worldwide, often developing as a complication of inflammatory bowel diseases. The Notch pathway plays a central role in intestinal homeostasia and its deregulation contributes to tumor development. Inhibition of Notch signaling through the Dll4 ligand shows anti-tumor activity against a variety of human and rodent tumors grafted in mice.

The aim of this work was to analyze Dll4 expression in both normal intestine and intestinal tumors, and determine the effect of Dll4 inhibition by using Dll4 heterozygous mice or administering a pharmacological inhibitor (soluble Dll4-Fc) in the mouse model of chemically induced colo-rectal cancer (CRC). To induce chronic colitis and CRC we combined the administration of azoxymethane, and repeated cycles of the proinflammatory dextran sodium sulfate in the drinking water, as previously described (Neufert et al. Nat Protoc 2: 1998) in either Dll4+/− mice or wild type mice treated with sDll4-Fc at a dose of 5mg/Kg/day, IP, 3x/wk from week 10 of AOM plus DSS treatment to week 14.

Dll4 expression was detected in the vascular endothelium as well as in both absorptive and secretive epithelium of the normal intestine and colorectal (CR) polyps. Both genetical (Dll4 allelic deletion, Dll4+/−) and pharmacological inhibition by the soluble extracellular domain of Dll4 (Dll4-Fc) led to significant reductions in the average number (12.5-fold in mutants, 3.7-fold in Dll4-Fc treated), average volume (1.6-fold in mutants, 2.3-fold in Dll4-Fc treated) and overall burden (15.2-fold in mutants, 6.3-fold in Dll4-Fc treated) of CR polyps, by inducing intratumoral apoptosis and disrupting proper tumor angiogenesis., leading to the formation of immature and non-functional blood vessels. Dll4 heterozygous mutants shown a 42.5% increase in tumor vascular density and a 13.9 % decrease in smooth muscle cell vascular recruitment, displaying increased vascular permeability and reduce vascular perfusion. Dll4-Fc treated mice displayed more proeminent vascular disruption, with a 127.5% increase in tumor vascular density and a 53.2% decrease in smooth muscle cell vascular recruitment, showing extensive vascular extravasation and poor perfusion of the tumor blood vessels.

In conclusion, Dll4Fc administration in chronic colitis-related CRC appears to constitute a promising therapeutical approach, capable of inhibiting the tumorigenic events as well as targeting the tumour vasculature and preventing tumor development.

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-285. doi:10.1158/1538-7445.AM2011-LB-285

Combination of Dll4/Notch and Ephrin-B2/EphB4 targeted therapy is highly effective in disrupting tumor angiogenesis

Background

Dll4/Notch and Ephrin-B2/EphB4 pathways play critical roles in tumor vessel development and maturation. This study evaluates the efficacy of the inhibition of both signaling pathways, alone and in combination, in reducing the growth of an autochthonous mouse tumor and assesses potential adverse effects.

Methods

We used the transgenic RIP1-Tag2 tumor model to study the effects of 1) inhibition of Dll4/Notch by either Dll4 allelic deletion or use of a soluble extracellular Dll4 (sDll4), 2) inhibition of Ephrin-B2/EphB4 signaling by a soluble extracellular EphB4 fused to albumin (sEphB4-Alb), and 3) inhibition of both pathways by sEphB4-Alb combined with either Dll4 allelic deletion or sDll4. To investigate adverse effects, we used inducible endothelial-specific Dll4 knock-out mice, treated with sEphB4-Alb, and carried out histopathological analysis.

Results

Dll4 allele deletion or soluble Dll4 treatment resulted in increased tumor vessel density, reduced mural cell recruitment and vessel perfusion which resulted in reduced tumor size. The soluble EphB4 instead reduced vessel density and vessel perfusion, leading to reduction of tumor size. Greater efficacy was observed when sEphB4-Alb was combined with either Dll4 allele deletion or sDll4 in regards to tumor size, vessel perfusion and mural cell recruitment. Induced endothelial specific Dll4 loss-of-function caused hepatic vascular alterations, which were prevented by concomitant sEphB4-Alb treatment.

Conclusion

Combination targeting of Dll4/Notch and Ephrin-B2/EphB4 has potential for clinical investigation, providing cumulative efficacy and increased safety over Dll4/Notch inhibition alone.

Loss of Notch signalling induced by Dll4 causes arterial calibre reduction by increasing endothelial cell response to angiogenic stimuli

Background

In the vascular system, Notch receptors and ligands are expressed mainly on arteries, with Delta-like 4 (Dll4) being the only ligand known to be expressed early during the development of arterial endothelial cells and capillaries. Dll4 null embryos die very early in development with severely reduced arterial calibre and lumen and loss of arterial cell identity.

Results

The current detailed analysis of these mutants shows that the arterial defect precedes the initiation of blood flow and that the arterial Dll4^-/- endothelial cells proliferate and migrate more actively. Dll4^-/- mutants reveal a defective basement membrane around the forming aorta and increased endothelial cell migration from the dorsal aorta to peripheral regions, which constitute the main causes of arterial lumen reduction in these embryos. The increased proliferation and migration of Dll4^-/- endothelial cells was found to coincide with increased expression of the receptors VEGFR-2 and Robo4 and with downregulation of the TGF-β accessory receptor Endoglin.

Conclusion

Together, these results strongly suggest that Notch signalling can increase arterial stability and calibre by decreasing the response of arterial endothelial cells to local gradients of pro-angiogenic factors like VEGF.

Inhibition of Dll4-mediated signaling induces proliferation of immature vessels and results in poor tissue perfusion

Vascular development is dependent on various growth factors and certain modifiers critical for providing arterial or venous identity, interaction with the surrounding stroma and tissues, hierarchic network formation, and recruitment of pericytes. Notch receptors and ligands (Jagged and Delta-like) play a critical role in this process in addition to VEGF. Dll4 is one of the Notch ligands that regulates arterial specification and maturation events. In the current study, we have shown that loss of function by either targeted allele deletion or use of a soluble form of Dll4 extracellular domain leads to inhibition of Notch signaling, resulting in increased vascular proliferation but defective maturation. Newly forming vessels have thin caliber, a markedly reduced vessel lumen, markedly reduced pericyte recruitment, and deficient vascular perfusion. sDll4 similarly induced defective vascular response in tumor implants leading to reduced tumor growth. Interference with Dll4-Notch signaling may be particularly desirable in tumors that have highly induced Dll4-Notch pathway.

A Monte Carlo multiple source model applied to radiosurgery narrow photon beams

Monte Carlo (MC) methods are nowadays often used in the field of radiotherapy. Through successive steps, radiation fields are simulated, producing source Phase Space Data (PSD) that enable a dose calculation with good accuracy. Narrow photon beams used in radiosurgery can also be simulated by MC codes. However, the poor efficiency in simulating these narrow photon beams produces PSD whose quality prevents calculating dose with the required accuracy. To overcome this difficulty, a multiple source model was developed that enhances the quality of the reconstructed PSD, reducing also the time and storage capacities. This multiple source model was based on the full MC simulation, performed with the MC code MCNP4C, of the Siemens Mevatron KD2 (6 MV mode) linear accelerator head and additional collimators. The full simulation allowed the characterization of the particles coming from the accelerator head and from the additional collimators that shape the narrow photon beams used in radiosurgery treatments. Eight relevant photon virtual sources were identified from the full characterization analysis. Spatial and energy distributions were stored in histograms for the virtual sources representing the accelerator head components and the additional collimators. The photon directions were calculated for virtual sources representing the accelerator head components whereas, for the virtual sources representing the additional collimators, they were recorded into histograms. All these histograms were included in the MC code, DPM code and using a sampling procedure that reconstructed the PSDs, dose distributions were calculated in a water phantom divided in 20000 voxels of 1 x 1 x 5 mm3. The model accurately calculates dose distributions in the water phantom for all the additional collimators; for depth dose curves, associated errors at 2sigma were lower than 2.5% until a depth of 202.5 mm for all the additional collimators and for profiles at various depths, deviations between measured and calculated values were less than 2.5% or 1 mm.

A new low-energy bremsstrahlung generator for GEANT4

The 2BN bremsstrahlung cross section is a well-adapted distribution to describe the radiative processes at low-electron kinetic energy (E(k) < 500 keV). In this work a method to implement this distribution in a Monte Carlo generator is developed.

Clear-PEM: a dedicated PET camera for improved breast cancer detection

Positron emission mammography (PEM) can offer a non-invasive method for the diagnosis of breast cancer. Metabolic images from PEM using 18F-fluoro-deoxy-glucose, contain unique information not available from conventional morphologic imaging techniques like X-ray radiography. In this work, the concept of Clear-PEM, the system presently developed in the frame of the Crystal Clear Collaboration at CERN, is described. Clear-PEM will be a dedicated scanner, offering better perspectives in terms of position resolution and detection sensitivity.

Application of GEANT4radiation transport toolkit to dose calculations in anthropomorphic phantoms

In this paper, we present a novel implementation of a dose calculation application, based on the GEANT4 Monte Carlo toolkit. Validation studies were performed with an homogeneous water phantom and an Alderson-Rando anthropomorphic phantom both irradiated with high-energy photon beams produced by a clinical linear accelerator. As input, this tool requires computer tomography images for automatic codification of voxel-based geometries and phase-space distributions to characterize the incident radiation field. Simulation results were compared with ionization chamber, thermoluminescent dosimetry data and commercial treatment planning system calculations. In homogeneous water phantom, overall agreement with measurements were within 1-2%. For anthropomorphic simulated setups (thorax and head irradiation) mean differences between GEANT4 and TLD measurements were less than 2%. Significant differences between GEANT4 and a semi-analytical algorithm implemented in the treatment planning system, were found in low-density regions, such as air cavities with strong electronic disequilibrium.

Pleomorphic xanthoastrocytoma of the cerebellum: illustrated review

Although rarely, the usually benign, supratentorial, grade II astrocytic tumour pleomorphic xanthoastrocytoma (PXA) may arise from the cerebellum. A review of the published cases of these PXAs is made including the author's own case of a 40 years-old man with a right cerebellopontine angle tumour, which recurred after a gross total resection. The major clinical and histopathological features of cerebellar PXAs are discussed, and factors playing a role in their biological behaviour, like post-surgical medical treatment, genetics and extent of leptomeningeal seeding are stressed.

Dosage-sensitive requirement for mouse Dll4 in artery development

Involvement of the Notch signaling pathway in vascular development has been demonstrated by both gain- and loss-of-function mutations in humans, mice, and zebrafish. In zebrafish, Notch signaling is required for arterial identity by suppressing the venous fate in developing artery cells. In mice, the Notch4 receptor and the Delta-like 4 (Dll4) ligand are specifically expressed in arterial endothelial cells, suggesting a similar role. Here we show that the Dll4 ligand alone is required in a dosage-sensitive manner for normal arterial patterning in development. This implicates Dll4 as the specific mammalian endothelial ligand for autocrine endothelial Notch signaling, and suggests that Dll4 may be a suitable target for intervention in arterial angiogenesis.

Basic dosimetry of radiosurgery narrow beams using Monte Carlo simulations: A detailed study of depth of maximum dose

In radiosurgery narrow photon beams, the depth of maximum dose d(max), in the beam central axis increases as the size of the additional collimator increases. This behavior is the opposite of what is observed in radiotherapy conventional beams. To understand this effect, experimental depth dose curves of the additional collimators were obtained for a Siemens KD2 linear accelerator in 6 MV photon mode and the shift of d(max) varied from 11.0 +/- 0.6 mm for the 5 mm collimator to 14.5 +/- 0.6 mm for the 23 mm collimator. Monte Carlo simulations showed that the photons that had no interactions in the additional collimators, contributing more than 90% to the total dose in water, were responsible for the shift in d(max). Monte Carlo simulations also showed that electrons originated from these photons and contributing to the dose deposit in water in the beam central axis could be divided in two groups: those that deposit energy far away from their point of origin (the point of the first photon collision in water) and those that deposit energy locally (originated at more than one photon collision in water). Applying a simplified model based on the fact that the photons originating Compton electrons (at the first and subsequent collisions) have similar characteristics in air for all the additional collimators, it was shown that these electrons were also responsible for the shift of d(max) in the beam central axis. Finally, it was shown that the changes in the initial gradients of the depth dose curves of the additional collimators were mainly due to electrons originated from the first photon collision in water.

[Central neurocytomas]

Central neurocytomas are a well-characterized group of neuronal tumors usually arising in the supratentorial ventricular cavities. We describe the anatomical and clinical study of seven of these neoplasms. Patients were in the first four decades of life, and tumors were usually located in one of the lateral ventricles. Surgical resection was subtotal in 6 cases. Light microscopic examination revealed predominantly benign lesions with morphological features similar to the so-called ependymoma of the foramen of Monro, of the oligodendrogliomas, and of the neuroblastomas. Immunohistochemistry and electron microscopy confirmed the diagnosis in each case, showing expression of neuron specific enolase and synaptophysin and containing microtubuli, neurosecretory granules, and presynaptic vesicles. In agreement with the literature, the authors stress the benign behaviour of most of these tumors and the need for systematic immunohistochemical and ultrastructural study. The actual roles of the extent of resection and of postoperative radiotherapy are still a matter of discussion.

[Neuroradiology in the physiopathologic diagnosis of subarachnoid hemorrhage--cerebral aneurysm]

The clinical importance of the cerebral aneurismatic lesion in well known. In Portugal we still do not have reliable statistics regarding the occurrence of the subarachnoid hemorrhage, however we can make a comparison through Kassel's and Drake's studies where they refer that annually 28,000 North-Americans suffer from subarachnoid hemorrhage attributed to the rupture of the cerebral aneurysm. This is a clinical situation that needs to be analyzed, more so because if it is not diagnosed and treated in time, it can cause a high level of morbidity and mortality. From 1984 to 1990, the authors studied 208 clinical cases of in-patients at the Santa Maria Hospital who had been diagnosed as having subarachnoid hemorrhage-cerebral aneurysm. They analyzed 172 cranium-encephalic Tomographies and 190 cerebral Angiographies. They found levels that overlapped the series already published with respect to the location of the lesion, dimensions and age groups involved. They tried to relate the presence aneurysm in the willis arterial circle with the occurrence of locoregional anatomic variants that were detected in 51% of the patients with aneurysm of the anterior communicating artery and in 33% of the cases in the posterior communicating artery. The high occurrence of serious forms of tomodensitrometric presentation should also be emphasized. As a matter of fact, 42.6% of the patients studied were grouped in degree IV of the Fisher Scale. This result translates the effort that is still required towards an early clinical and imaging diagnosis of warning hemorrhage to avoid or prevent a catastrophic hemorrhage recurrence.

[Nimodipine in subarachnoid hemorrhage]

The efficacy of nimodipine in decreasing mortality and morbidity of subarachnoid haemorrhage (HSA) is evaluated in 51 patients admitted to the Neurological and Neurosurgery Departments of the Santa Maria Hospital. Reductions of 2 x (0.65, 6.39) of the incidence of ischemia in the total group and of 2.1 x (0.58, 7.79) of mortality in the sub-group with initial severity of less than 4 points of the Hunt score were observed relatively to a comparable group of patients previously admitted who did not receive nimodipine. Randomized clinical trials that tested the effect of nimodipine in the context of HSA are reviewed.

[Intravascular therapy of giant cerebral aneurysm]

The endovascular therapy in cerebral aneurysms has met significant technical progress, specially related with new microcatheters and different types of detachable balloons. Reviewing seven cases of giant cerebral aneurysms treated by intra arterial approach, the authors present their results pointing out and discussing the different angiosurgical therapy that can actually be used.

Acquired crossed aphasia in a child

A case is reported of acquired aphasia in a 15-year-old right-handed boy, secondary to a right occipitotemporal tumour. He had aphasia, alexia, agraphia and visuospatial disturbances, which persisted after partial removal of the neoplasm. 15 days after surgery he had an episode of left focal seizures, after which the aphasia worsened. One month later he developed severe (global) aphasia associated with rostral extension of the tumour. Although crossed aphasia was previously considered common in children, there are few reports with anatomical confirmation. In the authors' own series of 31 children with acquired aphasia this is the only case of crossed aphasia, an incidence similar to that found in adult cases.

Contrecoup injury in the misdiagnosis of crossed aphasia

Crossed aphasia is reported to be more frequent in traumatic series than in series of patients with other pathologies. A right-handed young man suffered a closed-head trauma and became aphasic and hemiparetic on the left. CT scan revealed a right frontal-lobe hematoma. Neuropsychological examination revealed a fluent aphasia and a Gerstmann syndrome. These signs were compatible with left supramarginal gyrus syndrome. However, the presence of a right frontal-lobe lesion suggested that this patient could be a crossed aphasic. Subsequent EEG study showed a left occipitotemporal focus and a right frontal one. Aphasic signs could thus be due to the left lesion, which was the result of a contrecoup mechanism. Fluent aphasias have been reported in closed-head trauma with right frontal impact. Attention is called for the possible bias of including cases like this in series of traumatic crossed aphasia.

The prognostic significance of endodermal sinus tumor histology among patients treated for stage III nonseminomatous germ cell tumors of the testes

A retrospective study was undertaken to determine the prognostic significance of endodermal sinus tumor (EST) elements in 56 patients with Stage III nonseminatous germ cell tumors of the testes (NSGCTT). The study patients were treated with conventional vinblastine, bleomycin and cisplatinum chemotherapy prior to our recognition of EST as a distinct entity. Twenty-one (37.5%) of the patients had EST elements in their tumors. Nineteen patients had EST in their primary testis tumor, whereas two had EST in metastatic sites only. Prognostic criteria (tumor volume, Dixon-Moore classification and chemotherapy vinblastin and bleomycin [VB] and VB plus cisplatin [VB + P] ) were similar in EST and non-EST patients. Long-term disease-free survival was significantly poorer for patients with Stage III NSGCTT containing EST (38%) compared with those not containing EST (71%) (P = 0.04). All 12 patients with small volume disease (III-B1-III-B2), independent of the presence of EST, are alive and free of disease for more than 2 years. Only 6 of 18 patients (33%) with advanced disease and EST are alive and free of disease, whereas 17 of 26 (65%) of patients with advanced disease not containing EST are alive and free of disease (P = 0.074). The addition of single agent bolus cisplatin to the treatment of patients with advanced disease achieved no improvement in survival. Endodermal sinus tumor must be included in future studies of advanced Stage III NSGCTT as an important prognostic variable.

Doxorubicin, mitomycin-C, and 5-fluorouracil (DMF) in the treatment of metastatic hormonal refractory adenocarcinoma of the prostate, with a note on the staging of metastatic prostate cancer

Sixty-two patients with metastatic hormonal refractory adenocarcinoma of the prostate received a combination of doxorubicin, mitomycin-C, and 5-fluorouracil (DMF). Thirty (48%) of the patients achieved an objective response. Response criteria excluded disease "stabilization" as a manifestation of response. Four clinical prognostic categories were identified: osseous I (OI) had metastatic axial skeletal involvement (23 patients); osseous II (OII) had axial and extremity skeletaL involvement (18 patients); visceral I (VI) had pulmonary metastasis (9 patients); and visceral II (VII) had pulmonary metastasis and involvement of other viscera (12 patients). The 20 responding patients survived a median of 47.5 weeks, whereas the 32 nonresponding patients survived a median of 23.8 weeks (n = 0.002). Response rates were highest among patients with OI (52%) and VI (88%) disease; response rates were lower amont patients with OII (33%) and VII (33%) disease. Responding patients in each clinical category survived longer than nonresponding patients except for those patients with VII disease. The median duration of response for patients with OI disease was 11 months, for OII 9.5 months, for VI patients it was 6.5 months, and VII patients it was 5 months. DMF is an effective treatment of metastatic hormonal refractory prostate cancer, resulting in consistent objective responses. The staging system employed identifies four clinical categories of metastatic prostate cancer and allows for accurate comparison of diet and stratification of study populations.

Renal cell carcinoma: antitumor effects of leukocyte interferon

Partially purified human leukocyte (alpha) interferon was administered i.m. at a dose of 3 x 10(6) units/day to 19 patients with metastatic renal cell carcinoma. Five patients (26%) showed partial responses; two patients (10.5%), objective minor responses; three patients (16%), mixed effects (evidence of biological effect with regression of some lesions but concomitant progression); two patients (10.5%), disease stabilization; and seven patients (37%), progressive disease. All tumor responses were seen in lung or mediastinal metastases. Tumor response significantly correlated with interferon-induced leukopenia and granulocytopenia and with pretreatment performance status. Antibodies to interferon were found in one patient prior to treatment. We concluded that interferon is a potential active antitumor agent in patients with renal cell carcinoma.

The role of surgery following chemotherapy in stage III germ cell neoplasms

After curative chemotherapy 58 patients with metastatic germinal tumors and 2 with extragonadal germinal tumors underwent an operation either to confirm a clinical complete response or to remove a residual mass. Biomarker status was converted to negative in all patients. Retroperitoneal lymphadenectomy was done in 22 patients after a complete clinical response was achieved and in 23 after an apparent complete response was achieved except for a residual retroperitoneal mass. Thoracotomy was done for a residual mass in 13 patients, while 2 underwent bilateral thoracotomy. Scarring was found in 25 patients (42 per cent), teratoma in 14 (23 per cent) and active tumor in 17 (28 per cent). One patient with scarring and primary seminoma died of disseminated seminoma, while 1 with primary teratocarcinoma died of disseminated disease, for a false negative rate of 3 per cent. Four patients with a residual mass showed unexpected findings: 2 had granulomas in the lung, 1 had carcinoid of the lung and 1 had retroperitoneal neurofibroma. Thus, there was a 7 per cent incidence of a mass being other than scar, teratoma or residual tumor. There was 1 operative death and 10 deaths of tumor, for an 18 per cent death rate. Of the 17 patients with active tumor 9 responded to salvage chemotherapy with stable complete remission and a minimum followup of 18 months. In addition to the 60 patients the advanced disease in 10 was surgically debulked after failure of chemotherapy and this procedure was followed by salvage chemotherapy. All 10 patients died, with a median survival of 7 months. The lack of responsiveness to chemotherapy was not improved by incomplete removal of tumor.

The growing teratoma syndrome

Six patients with metastatic mixed germ-cell tumors who had been treated successfully with chemotherapy had recurring solitary enlarging masses. Four had enlarging pulmonary masses and two patients had enlarging abdominal masses. Each had the presumed chemotherapy refractory mass surgically resected and was found to have mature teratoma with absence of malignant histologies. The growth in two patients can be attributed to tense and expansile cysts; the remaining four had firm masses. All patients remain free of disease without further therapy at 5, 13, 14, 25, 66, and 108 months. Early recognition of this previously unreported and unusual clinical circumstance of a benign teratoma to grow after chemotherapy will allow for surgical salvage.