Phenotypic screen identifies calcineurin-sparing FK506 analogs as BMP potentiators for treatment of acute kidney injury

Acute kidney injury (AKI) is a life-threatening disease with no known curative or preventive therapies. Data from multiple animal models and human studies have linked dysregulation of bone morphogenetic protein (BMP) signaling to AKI. Small molecules that potentiate endogenous BMP signaling should have a beneficial effect in AKI. We performed a high-throughput phenotypic screen and identified a series of FK506 analogs that act as potent BMP potentiators by sequestering FKBP12 from BMP type I receptors. We further showed that calcineurin inhibition was not required for this activity. We identified a calcineurin-sparing FK506 analog oxtFK through late-stage functionalization and structure-guided design. OxtFK demonstrated an improved safety profile in vivo relative to FK506. OxtFK stimulated BMP signaling in vitro and in vivo and protected the kidneys in an AKI mouse model, making it a promising candidate for future development as a first-in-class therapeutic for diseases with dysregulated BMP signaling.

A Distinctive Genomic and Immunohistochemical Profile for NOTCH3 and PDGFRB in Myofibroma With Diagnostic and Therapeutic Implications

Introduction. Myofibromas are rare tumors of pericytic lineage, typically affecting children, and are sometimes aggressive. A subset of sporadic and familial myofibromas have activating variants in PDGFRB. The relationship of myofibroma and PDGFRB to the NOTCH pathway has not yet been described. Methods. Ten myofibroma cases were sequenced with a targeted panel of 447 genes, including copy number variation and selected fusions. Immunohistochemical analysis of total NOTCH3 and activated NOTCH3 was assessed for all 10 myofibroma cases, and a series of histologic mimics (n = 20). Results. Alterations identified by next-generation sequencing included PDGFRB sequence variants in 8/10 cases (80%), a NOTCH3 variant in 1/10 cases (10%), and a NOTCH2 variant in 1/10 cases (10%). All 10 cases also showed a pattern of low-amplitude (1.5- to 2-fold) copy number alterations including gains in PDGFRB and NOTCH3. Ten of 10 myofibromas (100%) showed cytoplasmic staining for total NOTCH3 and 9 of 10 cases (90%) showed nuclear staining for activated NOTCH3. Within the control cohort of histologic mimics, 3 of 3 nodular fasciitis cases (100%) were positive for activated and total NOTCH3, and the remaining 17 cases were negative for pan NOTCH3, while 3 of 3 desmoid-type fibromatosis cases (100%) showed patchy weak nuclear staining for activated NOTCH3. Discussion. Our findings suggest a common pathway of PDGFRB/NOTCH3 activation in myofibromas, even in cases that lack PDGFRB sequence variants. These results support the pericytic lineage of myofibroma. Identification of the characteristic genomic alterations or immunohistochemical staining pattern may facilitate a difficult pathologic diagnosis, and support the use of targeted treatments.

Discovery of a ZIP7 inhibitor from a Notch pathway screen

The identification of activating mutations in NOTCH1 in 50% of T cell acute lymphoblastic leukemia has generated interest in elucidating how these mutations contribute to oncogenic transformation and in targeting the pathway. A phenotypic screen identified compounds that interfere with trafficking of Notch and induce apoptosis via an endoplasmic reticulum (ER) stress mechanism. Target identification approaches revealed a role for SLC39A7 (ZIP7), a zinc transport family member, in governing Notch trafficking and signaling. Generation and sequencing of a compound-resistant cell line identified a V430E mutation in ZIP7 that confers transferable resistance to the compound NVS-ZP7-4. NVS-ZP7-4 altered zinc in the ER, and an analog of the compound photoaffinity labeled ZIP7 in cells, suggesting a direct interaction between the compound and ZIP7. NVS-ZP7-4 is the first reported chemical tool to probe the impact of modulating ER zinc levels and investigate ZIP7 as a novel druggable node in the Notch pathway.

Characterization of activating mutations of NOTCH3 in T-cell acute lymphoblastic leukemia and anti-leukemic activity of NOTCH3 inhibitory antibodies

Notch receptors have been implicated as oncogenic drivers in several cancers, the most notable example being NOTCH1 in T-cell acute lymphoblastic leukemia (T-ALL). To characterize the role of activated NOTCH3 in cancer, we generated an antibody that detects the neo-epitope created upon gamma-secretase cleavage of NOTCH3 to release its intracellular domain (ICD3), and sequenced the negative regulatory region (NRR) and PEST domain coding regions of NOTCH3 in a panel of cell lines. We also characterize NOTCH3 tumor-associated mutations that result in activation of signaling and report new inhibitory antibodies. We determined the structural basis for receptor inhibition by obtaining the first co-crystal structure of a NOTCH3 antibody with the NRR protein and defined two distinct epitopes for NRR antibodies. The antibodies exhibit potent anti-leukemic activity in cell lines and tumor xenografts harboring NOTCH3 activating mutations. Screening of primary T-ALL samples reveals that two of 40 tumors examined show active NOTCH3 signaling. We also identified evidence of NOTCH3 activation in 12 of 24 patient-derived orthotopic xenograft models, two of which exhibit activation of NOTCH3 without activation of NOTCH1. Our studies provide additional insights into NOTCH3 activation and offer a path forward for identification of cancers that are likely to respond to therapy with NOTCH3 selective inhibitory antibodies.

Mastermind recruits CycC:CDK8 to phosphorylate the Notch ICD and coordinate activation with turnover

Notch signaling releases the Notch receptor intracellular domain (ICD), which complexes with CBF1 and Mastermind (MAM) to activate responsive genes. We previously reported that MAM interacts with CBP/p300 and promotes hyperphosphorylation and degradation of the Notch ICD in vivo. Here we show that CycC:CDK8 and CycT1:CDK9/P-TEFb are recruited with Notch and associated coactivators (MAM, SKIP) to the HES1 promoter in signaling cells. MAM interacts directly with CDK8 and can cause it to localize to subnuclear foci. Purified recombinant CycC:CDK8 phosphorylates the Notch ICD within the TAD and PEST domains, and expression of CycC:CDK8 strongly enhances Notch ICD hyperphosphorylation and PEST-dependent degradation by the Fbw7/Sel10 ubiquitin ligase in vivo. Point mutations affecting conserved Ser residues within the ICD PEST motif prevent hyperphosphorylation by CycC:CDK8 and stabilize the ICD in vivo. These findings suggest a role for MAM and CycC:CDK8 in the turnover of the Notch enhancer complex at target genes.

A lysimeter experiment to investigate temporal changes in the availability of pesticide residues for leaching

Leaching of three pesticides (isoproturon, chlorotoluron and triasulfuron) and a tracer (bromide) were determined in four contrasting soils ranging in texture from sandy loam to clay. The compounds were applied to undisturbed columns of soil and four columns for each soil were randomly selected and leached with 24-mm equivalent of water at prescribed time intervals (3, 9, 24, 37 and 57 d after application). A rapid decline in leached loads of isoproturon and chlorotoluron as time from application to irrigation increased was observed in all soils. In contrast, triasulfuron and bromide loads only decreased rapidly in the clay soil. Bromide losses decreased with decreasing clay contents of the soil and therefore with a decrease in structural development. Magnitudes of pesticide losses varied from soil to soil, depending on structural development and the organic carbon content. Pesticide degradation experiments on disturbed and undisturbed soil samples showed that the rapid decline of leached loads with time was faster than could be explained by degradation alone. Five physico-chemical processes are put forward to explain the different patterns of pesticide leached loads observed in the soils: (1) relative extent of preferential flow, (2) sorption capacity of the compounds to the different soils, (3) extent of degradation of the compounds in the soil, (4) variation in sorption kinetics between compounds associated with pesticide diffusion into soil aggregates, and (5) protection of the compounds by a combination of intra-aggregate diffusion and the presence of preferential flow pathways.

BAF60a mediates critical interactions between nuclear receptors and the BRG1 chromatin-remodeling complex for transactivation

Nuclear hormone receptors are ligand-dependent transcriptional regulators that modulate chromatin structure. However, the precise molecular mechanisms by which receptors recruit chromatin-remodeling activity are not fully elucidated. We show that in the absence of its ligand-binding domain, the glucocorticoid receptor (GR) is able to interact with both nuclear receptor coactivators and the BRG1 chromatin-remodeling complex in vivo. Individually, the GR makes direct interactions with BRG1-associated factor 60a (BAF60a) and BAF57, but not with BRG1, BAF155, or BAF170. Further, BAF60a possesses at least two interaction surfaces, one for GR and BRG1 and a second for BAF155 and BAF170. A GR mutant, GR(R488Q), that fails to interact with BAF60a in vitro has reduced chromatin-remodeling activity and reduced transcriptional activity from the promoter assembled as chromatin in vivo. Stable expression of a BAF60a truncation mutant, BAF60a4-140, caused chromatin-specific loss of GR functions in vivo. In the presence of the BAF60a mutant, the GR fails to interact with the BRG1 complex and consequently is also deficient in its ability to activate transcription from chromatin. Thus, in addition to previously identified BAF250, BAF60a may provide another critical and direct link between nuclear receptors and the BRG1 complex that is required for promoter recruitment and subsequent chromatin remodeling.

Mastermind mediates chromatin-specific transcription and turnover of the Notch enhancer complex

Signaling through the Notch pathway activates the proteolytic release of the Notch intracellular domain (ICD), a dedicated transcriptional coactivator of CSL enhancer-binding proteins. Here we show that chromatin-dependent transactivation by the recombinant Notch ICD-CBF1 enhancer complex in vitro requires an additional coactivator, Mastermind (MAM). MAM provides two activation domains necessary for Notch signaling in mammalian cells and in Xenopus embryos. We show that the central MAM activation domain (TAD1) recruits CBP/p300 to promote nucleosome acetylation at Notch enhancers and activate transcription in vitro. We also find that MAM expression induces phosphorylation and relocalization of endogenous CBP/p300 proteins to nuclear foci in vivo. Moreover, we show that coexpression with MAM and CBF1 strongly enhances phosphorylation and proteolytic turnover of the Notch ICD in vivo. Enhanced phosphorylation of the ICD and p300 requires a glutamine-rich region of MAM (TAD2) that is essential for Notch transcription in vivo. Thus MAM may function as a timer to couple transcription activation with disassembly of the Notch enhancer complex on chromatin.

Analyzing the contributions of chromatin structure in nuclear hormone receptor activated transcription in vivo

The authors have described three approaches for analyzing the chromatin architecture of a steroid-responsive promoter. Mnase allows one to map the positions of nucleosomes on the target gene. The more sensitive restriction enzyme hypersensitivity procedure permits detection of changes in chromatin architecture upon hormonal stimulation. Additional insight into transcriptional regulation of a gene can be obtained by using the related ExoIII footprinting protocol, which provides complementary data on transcription factor binding to chromatin templates. The use of these in vivo chromatin analysis techniques have provided evidence for a role of chromatin structure in regulation of transcription of steroid-responsive promoters including MMTV (2,7,10,14), tyrosine aminotransferase (15), TR beta A (16-19), and retinoic acid receptor beta (RAR beta) (20).

Chromatin-specific regulation of LEF-1-beta-catenin transcription activation and inhibition in vitro

Transcriptional activation of Wnt/Wg-responsive genes requires the stabilization and nuclear accumulation of beta-catenin, a dedicated coactivator of LEF/TCF enhancer-binding proteins. Here we report that recombinant beta-catenin strongly enhances binding and transactivation by LEF-1 on chromatin templates in vitro. Interestingly, different LEF-1 isoforms vary in their ability to bind nucleosomal templates in the absence of beta-catenin, owing to N-terminal residues that repress binding to chromatin, but not nonchromatin, templates. Transcriptional activation in vitro requires both the armadillo (ARM) repeats and the C terminus of beta-catenin, whereas the phosphorylated N terminus is inhibitory to transcription. A fragment spanning the C terminus (CT) and ARM repeats 11 and 12 (CT-ARM), but not the CT alone, functions as a dominant negative inhibitor of LEF-1-beta-cat activity in vitro and can block ATP-dependent binding of the complex to chromatin. LEF-1-beta-cat transactivation in vitro was also repressed by inhibitor of beta-catenin and Tcf-4 (ICAT), a physiological inhibitor of Wnt/Wg signaling that interacts with ARM repeats 11 and 12, and by the nonsteroidal anti-inflammatory compound, sulindac. None of these transcription inhibitors (CT-ARM, ICAT, or sulindac) could disrupt the LEF-1-beta-cat complex after it was stably bound to chromatin. We conclude that the CT-ARM region of beta-catenin functions as a chromatin-specific activation domain, and that several inhibitors of the Wnt/Wg pathway directly modulate LEF-1-beta-cat activity on chromatin.

Influence of topsoil tilth and soil moisture status on losses of pesticide to drains from a heavy clay soil

Twelve lysimeters with a surface area of 0.5 m2 and a length of 60 cm were taken over mole drains from a Denchworth heavy clay soil and divided into two groups with either a standard agricultural tilth or a finer topsoil tilth. The influence of topsoil tilth on leaching of the herbicide isoproturon and a bromide tracer was evaluated over a winter season. The effect of variations in soil moisture status in the immediate topsoil on leaching of isoproturon, chlorotoluron and linuron was investigated in the following winter season. Here, water inputs were controlled such that lysimeters received 50 mm at a maximum intensity of 2 mm h-1 over a 4-week period with herbicides applied on day 15. Three treatments received the water either all prior to application, all after application, or evenly spread over the 4-week period. Leaching losses of the three herbicides were monitored for a subsequently drainage event. Analysis of covariance showed a significant effect of topsoil tilth and total flow on both the maximum concentrations (P = 0.034) and total losses (P = 0.012) of isoproturon in drainflow. Both concentrations and losses were c 35% smaller from lysimeters with the finer tilth. However, generation of the fine tilth in the field was restricted by a wet autumn and this is not considered a reliable management option for reducing pesticide losses from heavy clay soils. In the second experiment, variation in soil moisture content prior to and after application did not have any significant effect (P < 0.05) upon subsequent losses of the three herbicides to drains.

Age is the major determinant of recurrence in pediatric differentiated thyroid carcinoma

BACKGROUND

A relationship between young age and increased risk of recurrence of pediatric differentiated thyroid carcinoma has been suggested; however, no attempts have been made to assess the prognostic factors or efficacy of treatment in very young children with this malignancy. The objectives of this study were to evaluate the association of age with outcome in pediatric differentiated thyroid carcinoma and to compare the clinical, pathologic, prognostic, and treatment variables between younger and older children with this disease.

PROCEDURE

A retrospective review of all patients presenting to the British Columbia's Children's Hospital or British Columbia Cancer Agency <17 years of age at diagnosis with differentiated thyroid carcinoma between January, 1955, and December, 1996, was completed.

RESULTS

Thirty-eight patients were identified, 12 of whom were </=10 years of age. The overall and relapse-free survivals at 20 years were 100% and 32.2%, respectively. Age at diagnosis was the only determinant of time to recurrence on univariate and multivariate regression analysis of prognostic factors (P = 0.022). The 20 year relapse-free survival for children < or =10 years of age was 10.1% vs. 48.3% for children >10 years. An association between young age and extrathyroidal tumor invasion was identified (P = 0.016); however, the latter factor did not independently predict outcome. There was a trend for suppressive doses of thyroid hormone to improve outcome, particularly with increasing age at diagnosis, but this was not statistically significant.

CONCLUSIONS

Age is the major determinant of recurrence in pediatric differentiated thyroid carcinoma. The results suggest different tumor biology in young children requiring novel approaches to therapy to decrease recurrence rates.

The mouse mammary tumor virus promoter adopts distinct chromatin structures in human breast cancer cells with and without glucocorticoid receptor

Steroid receptors represent a class of transcription regulators that act in part by overcoming the often repressive nature of chromatin to modulate gene activity. The mouse mammary tumor virus (MMTV) promoter is a useful model for studying transcriptional regulation by steroid hormone receptors in the context of chromatin. The chromatin architecture of the promoter prevents the assembly of basal transcription machinery and binding of ubiquitous transcription factors. However, in human breast carcinoma T47D cells lacking the glucocorticoid receptor (GR), but expressing the progesterone receptor (PR), nucleosome B (nuc B) assumes a constitutively hypersensitive chromatin structure. This correlation led us to test the hypothesis that the chromatin structure of nuc B was dependent on GR expression in T47D cells. To examine this possibility, we stably co-transfected the MMTV promoter and the GR into T47D cells that lacked both the GR and the PR. We found that in T47D cells that lack both the GR and the PR or express only the GR, nuc B assumes a constitutively "open" chromatin structure, which allows hormone independent access by restriction endonucleases and transcription factors. These results suggest that in GR(+)/pr(-) T47D cells, the MMTV chromatin structure permits GR transcriptional activation, independent of chromatin remodeling.

Selective activation of the glucocorticoid receptor by steroid antagonists in human breast cancer and osteosarcoma cells

Steroid hormones regulate the transcription of numerous genes via high affinity receptors that act in concert with chromatin remodeling complexes, coactivators and corepressors. We have compared the activities of a variety of glucocorticoid receptor (GR) antagonists in breast cancer and osteosarcoma cell lines engineered to stably maintain the mouse mammary tumor virus promoter. In both cell types, GR activation by dexamethasone occurs via the disruption of mouse mammary tumor virus chromatin structure and the recruitment of receptor coactivator proteins. However, when challenged with a variety of antagonists the GR displays differential ability to activate transcription within the two cell types. For the breast cancer cells, the antagonists fail to activate the promoter and do not promote the association of the GR with either remodeling or coactivator proteins. In contrast, in osteosarcoma cells, the antiglucocorticoids, RU486 and RU43044, exhibit partial agonist activity. The capacity of these antagonists to stimulate transcription in the osteosarcoma cells is reflected in the ability of the RU486-bound receptor to remodel chromatin and associate with chromatin-remodeling proteins. Similarly, the observation that the RU486-bound receptor does not fully activate transcription is consistent with its inability to recruit receptor coactivator proteins.

Ewing sarcoma of the rib: results of an intergroup study with analysis of outcome by timing of resection

OBJECTIVE

We sought to establish the outcome and optimal therapeutic sequence for patients with nonmetastatic Ewing sarcoma/primitive neuroectodermal tumor of the chest wall.

METHODS

Patients 30 years of age or younger with nonmetastatic Ewing sarcoma/primitive neuroectodermal tumor of the bone were randomly assigned to receive vincristine, doxorubicin, cyclophosphamide, and dactinomycin or those drugs alternating with ifosfamide and etoposide. Local control was obtained with an operation, radiotherapy, or both.

RESULTS

Fifty-three (13.4%) of 393 patients had primary tumors of the chest wall (all rib). Event-free survival at 5 years was 57% for the chest wall compared with 61% for other sites (P >.2). Ifosfamide and etoposide improved outcome in the overall group (5-year event-free survival, 68% vs 54%; P =.002), and a similar trend occurred in chest wall lesions (5-year event-free survival, 64% vs 51%). Patients with chest wall lesions had more attempts at initial surgical resection (30%) than those with other primary tumor sites (8%, P <.01). The attempt at initial resection for chest wall lesions did not correlate with size. Initial resections at other sites were restricted to smaller tumors. Initial resection resulted in negative pathologic margins in 6 of 16 patients, whereas the delayed resection resulted in negative margins in 17 of 24 patients (P =.05). Although there was no difference in survival by timing of the operation in rib lesions, a higher percentage of patients with initial surgical resection received radiation than those with resection after initial chemotherapy (P =. 13).

CONCLUSIONS

Although rib primary tumors are significantly larger than tumors found in other sites, their outcome is similar. We favor delayed resection whenever possible to minimize the number of patients requiring radiation therapy.

Pion conformal radiation of prostate cancer: results of a randomized study

PURPOSE

To compare the efficacy of pion radiation therapy with conventional external beam photon therapy, for the treatment of locally advanced stage T3/4, N0, M0 adenocarcinoma of the prostate.

METHODS AND MATERIALS

Two hundred seventeen eligible patients were randomly allocated to either photon or pion therapy. No adjuvant hormone therapy was used.

RESULTS

Median follow-up was 42 months (range 2-90). Acute bladder toxicity was worse in the pion arm, p = 0.2, but other acute toxicity did not differ. Late grade 2 toxicity was significantly less in the pion arm (29% at 5 years versus 48%, p = 0.002), but late grade 3 or 4 toxicity did not differ. Clinical local control was not significantly different between treatment arms (64% after 5 years with photons, 56% with pions, p = 0.6). Cause-specific and overall survival also did not differ (p = 0.7). There was a significant delay in time to first failure in the photon arm, largely as a result of decreased biochemical relapse, p = 0.01. A multivariate analysis is presented.

CONCLUSION

Pion therapy was well tolerated, with increased acute toxicity and significantly decreased late tissue injury. This contrasts with the late toxicity observed with higher LET particle therapy such as neutron therapy. No improvement in local control with pion therapy was observed.

Chromatin remodelling by the glucocorticoid receptor requires the BRG1 complex

The assembly of transcriptional regulatory DNA sequences into chromatin plays a fundamental role in modulating gene expression. The promoter of the mouse mammary-tumour virus (MMTV) is packaged into a regular array of nucleosomes when it becomes stably integrated into mammalian chromosomes, and has been used to investigate the relationship between chromatin architecture and transcriptional activation by the hormone-bound glucocorticoid and progesterone receptors. In mammalian cells that express both of these receptors, the progesterone receptor activates transcription from transiently transfected MMTV DNA but not from organized chromatin templates. Moreover, the activated progesterone receptor inhibits the chromatin remodelling and consequent transcriptional stimulation that is mediated by the glucocorticoid receptor. Here we investigate the mechanism of this inhibition by characterizing the interaction of the glucocorticoid receptor with transcriptional co-activator and chromatin remodelling protein complexes. We show that when this receptor is prevented from interacting with the hBRG1/BAF chromatin remodelling complex, it can activate transcription from transiently transfected DNA but not from organized chromatin templates. Our results indicate that it may be possible to separate the transcriptional activation and chromatin remodelling activities of proteins that interact with hormone receptors.

MOPP or radiation in addition to ABVD in the treatment of pathologically staged advanced Hodgkin's disease in children: results of the Children's Cancer Group Phase III Trial

PURPOSE

A randomized trial designed to compare mechlorethamine, vincristine, procarbazine, and prednisone (MOPP)/doxorubicin, bleomycin, vinblastine, and daccarbazine (ABVD) (regimen A) with ABVD plus low-dose regional (extended-field) radiation therapy (EF RT) (regimen B) for the treatment of children and adolescents with stages III and IV Hodgkin's disease was conducted by the Children's Cancer Group (CCG-521) from 1986 until 1990.

PATIENTS AND METHODS

One hundred eleven eligible patients were randomized, 57 to regimen A and 54 to regimen B. All patients had pathologically verified stage III or stage IV Hodgkin's disease.

RESULTS

Overall survival (S) is 87% at 4 years and event-free survival (EFS) is 82%. Patients randomized to ABVD plus EF RT have a 4-year EFS of 87% compared with 77% for patients randomized to MOPP/ABVD (P = .09, two-sided). Patients randomized to ABVD plus EF RT have a 4-year S of 90% compared with 84% for patients randomized to MOPP/ABVD (P = .45, two-sided). Significant prognostic factors in multivariate analysis for EFS are stage of disease, erythrocyte sedimentation rate (ESR) at diagnosis, liver size at diagnosis, and, among stage III patients, the size of the mediastinal mass at diagnosis. The acute toxicities of treatment are largely hematopoietic in nature, whereas acute pulmonary and cardiac toxicities are modest and not limiting.

CONCLUSION

The results of this study show that, in advanced-stage Hodgkin's disease in children, equivalent results can be obtained by the addition of either MOPP or low-dose EF RT to the ABVD regimen; whether the addition of either contributes to outcome was not addressed in this study and will require additional testing. It is clear, however, that MOPP chemotherapy can safely be eliminated from front-line combination chemotherapy regimens for advanced Hodgkin's disease in pediatric patients.

Antiprogestins mediate differential effects on glucocorticoid receptor remodeling of chromatin structure

We examined the mechanism(s) by which the progesterone receptor (PR) is able to inhibit glucocorticoid receptor (GR) activation from the mouse mammary tumor virus (MMTV) promoter in vivo. Using specific hormone antagonists, we demonstrate that the PR complexed with an type II antiprogestin blocks glucocorticoid-induced activation of the MMTV promoter. However, when complexed with a type I antiprogestin the PR is unable to block glucocorticoid-induced activation. PR repression of GR activity results from the inhibition of the ability of the GR to remodel chromatin such that the antiprogestin-occupied/PR prevents the glucocorticoid induced assembly of a preinitiation complex at MMTV promoter. These experiments suggest that the specific chromatin organization of the MMTV promoter provides a mechanism for regulating cross-talk between the GR and PR in vivo.

Chromatin modulation of glucocorticoid and progesterone receptor activity

Steroid hormone receptors are ligand-activated transcription factors that enhance or repress gene expression. They act by binding to target sites within the promoters of genes assembled as chromatin. Chromatin structure is modified in response to steroid hormones and represents a critical step in steroid receptor signaling. Recent experiments demonstrate that the progesterone and glucocorticoid receptors are differentially influenced by this arrangement of DNA and histones. One of the most important developments in the steroid hormone receptor field has been the identification of coactivators and cointegrators, some of which are histone acetyltransferases. These proteins appear to play an important role in mediating ligand activation of transcription, although their exact role on chromatin templates is undefined.

Metastatic primitive neuroectodermal tumour of the ovary: successful treatment with mega-dose chemotherapy followed by peripheral blood progenitor cell rescue

Primitive neuroectodermal tumours (PNET) of the ovary are rare, aggressive tumours which are associated with high morbidity and mortality. Previously reported cases have shown limited response to therapy in patients presenting with metastatic disease and survival rates have been discouragingly low. We report the case of a 13-year-old girl who presented with a primary ovarian PNET and extensive metastatic disease. Pathologic studies confirmed the neural origin of the tumour and its morphologic appearance of neuroblastoma. Incomplete surgical resection was followed by treatment with aggressive multi-agent chemotherapy including cis-platinum, etoposide, cyclophosphamide, anddoxorubicin as per a neuroblastoma treatment protocol. Complete clinical remission ensued and she received consolidative therapy with myeloablative doses of thiotepa, melphalan, and carboplatin followed by autologous peripheral blood progenitor cell rescue. All therapy was well tolerated and the patient remains in complete remission with no evidence of disease 18 months from presentation. Mega-dose chemotherapy followed by progenitor cell rescue may provide optimal therapy for patients presenting with metastatic ovarian PNET.

Analysis of chromatin structure in vivo

A number of important nuclear processes including replication, recombination, repair, and transcription involve the interaction of soluble nuclear proteins with DNA assembled as chromatin. Recent progress in a number of experimental systems has focused attention on the influence chromatin structure may exert on gene regulation in eukaryotes. With the advent of new technologies for the analysis of chromatin structure in vivo, studies evaluating the influence of chromatin structure on gene transcription have become feasible for a number of systems. This article serves as an introduction to the use of restriction endonucleases to define nucleosomal organization and characterize changes in this organization that accompany transcriptional activation in vivo. The procedure includes the isolation of intact transcriptionally competent nuclei, limited digestion with specific restriction endonucleases, and purification of the DNA. This DNA serves as the substrate for a linear amplification using single primers that generate enzyme-specific DNA fragments, which are then resolved by electrophoresis. Specific examples related to our studies of the influence of chromatin structure on steroid hormone regulation of transcription from the mouse mammary tumor virus promoter are provided to illustrate this technique and several novel variations. Alternative methods for analysis of chromatin architecture using DNase I, micrococcal nuclease, permanganate, and methidiumpropyl-EDTA-iron(II) are also described. Through the use of these methodologies one is able to determine both the translational and the rotational positions for a given nucleosome as well as quantify changes at a specific nucleosome in response to regulatory and developmental signals.

Immunosuppressive therapy: a potential alternative to bone marrow transplantation as initial therapy for acquired severe aplastic anemia in childhood?

PURPOSE

Currently bone marrow transplantation (BMT) with an HLA-identical sibling donor is recommended as optimal therapy for children with acquired severe aplastic anemia (SAA). Immunosuppressive therapy (IST) has become a very successful initial therapy for SAA in children lacking a related bone marrow donor. We wished to evaluate whether current IST regimens may be as efficacious as BMT.

PATIENTS AND METHODS

A retrospective review identified children treated for SAA over a 12-year period. Children with a related donor received a BMT. Children lacking a donor were treated with IST followed by a "rescue" BMT if IST was ineffective. IST consisted of anti-thymocyte globulin and steroid +/- cyclosporine A. Transfusion independence and survival rates were compared between the two groups.

RESULTS

Twenty-seven children were identified. Nine received a related BMT; seven of these survive and are transfusion independent (median follow-up 54 months). Sixteen of 18 patients who received IST are transfusion-independent survivors, including three of four patients who received a rescue BMT (median follow-up 33.5 months). Actuarial survival is 75% (95% CI = 45%, 105%) and 92% (95% CI = 78%, 107%) for the BMT and IST groups, respectively (p = 0.15). Severe toxicity was not experienced by any patient as a result of IST.

CONCLUSIONS

Equivalent rates of transfusion independence and survival were experienced by patients receiving BMT and IST. We propose that a prospective trial be undertaken to evaluate IST as initial therapy in all children with SAA, to be followed by BMT if there is inadequate response.

Pion radiation for high grade astrocytoma: results of a randomized study

PURPOSE

This study attempted to compare within a randomized study the outcome of pion radiation therapy vs. conventional photon irradiation for the treatment of high-grade astrocytomas.

METHODS AND MATERIALS

Eighty-four patients were randomized to pion therapy (33-34.5 Gy pi), or conventional photon irradiation (60 Gy). Entry criteria included astrocytoma (modified Kernohan high Grade 3 or Grade 4), age 18-70, Karnofsky performance status (KPS) > or = 50, ability to start irradiation within 30 days of surgery, unifocal tumor, and treatment volume < 850 cc. The high-dose volume in both arms was computed tomography enhancement plus a 2-cm margin. The study was designed with the power to detect a twofold difference between arms.

RESULTS

Eighty-one eligible patients were equally balanced for all known prognostic variables. Pion patients started radiation 7 days earlier on average than photon patients, but other treatment-related variables did not differ. There were no significant differences for either early or late radiation toxicity between treatment arms. Actuarial survival analysis shows no differences in terms of time to local recurrence or overall survival where median survival was 10 months in both arms (p = 0.22). The physician-assessed KPS and patient-assessed quality of life (QOL) measurements were generally maintained within 10 percentage points until shortly before tumor recurrence. There was no apparent difference in the serial KPS or QOL scores between treatment arms.

CONCLUSION

In contrast to high linear energy transfer (LET) therapy for central nervous system tumors, such as neutron or neon therapy, the safety of pion therapy, which is of intermediate LET, has been reaffirmed. However, this study has demonstrated no therapeutic gain for pion therapy of glioblastoma.

Immune reaction induced by X-rays and pions and its stimulation by schizophyllan (SPG)

Female C57BL/6 mice aged 6-8 weeks with transplanted Lewis lung cancer cells were used to investigate the anti-tumour effects and immune reactions in tumour tissue induced by X-ray and pion irradiation and their modification by schizophyllan (SPG). The effect of SPG on the rate of lung metastasis and the survival time of the mice was also studied using the same tumour system. These studies showed that in this tumour system the "practical' relative biological effectiveness (RBE) of pions was 1.33 in the dose ranges used (3 Gy x 4 = P3; 6 Gy x 4 = P6). SPG increased the suppression of tumour growth associated with moderate doses of radiation: X-rays (4 Gy x 4 = X4) or P3. SPG also decreased the number of lung metastases and prolonged the life span of the mice, these effects being independent of radiation. The addition of SPG to radiation increased both the macrophage infiltration and T-lymphocyte infiltration in the local tumour and the lung nodules. There did not appear to be any major differential effect of SPG on the pion-treated mice compared with those treated with X-rays.

Steroid hormone receptor status defines the MMTV promoter chromatin structure in vivo

The ability to respond to small signalling molecules such as steroid hormones is important for many physiological processes. Steroid hormones act through a group of high affinity receptors that regulate transcription by binding to hormone response elements (HREs) located within the promoters of target genes, which themselves are organized with nuclear proteins to form chromatin. To dissect the mechanisms(s) of steroid hormone action we have used the steroid inducible mouse mammary tumor virus (MMTV) promoter as a model system. The MMTV promoter is assembled into a phased array of nucleosomes that are specifically positioned in rodent cells. Induction of transcription by glucocorticoids is accompanied by the appearance of a hypersensitive region in the proximal promoter which allows the hormone dependent assembly of a preinitiation complex including transcription factors such as nuclear factor 1 (NF1) and the octamer transcription factor (OTF). Surprisingly, when introduced by transient transfection, the progesterone receptor (PR) is unable to activate this promoter in vivo, a finding that may result from its inability to alter MMTV promoter chromatin. In an attempt to investigate the failure of the PR to activate the promoter, we have stably introduced the MMTV promoter into human T47D breast cancer cells that express high levels of the PR. In contrast to what has been observed previously in rodent cells, the MMTV templates resident in human breast cancer cells adopt a novel and constitutively open chromatin structure. The constitutively open chromatin structure is accompanied by the hormone independent loading of transcription factors including the PR and NF1. In T47D cells that stably express the glucocorticoid receptor, the MMTV promoter responds to glucocorticoids, but not progestins, and displays glucocorticoid induced restriction enzyme hypersensitivity and transcription factor loading. These findings suggest that the organization of the MMTV chromatin structure is dependent upon the cell type and receptor status of the recipient cell into which the MMTV promoter is stably introduced.

Central neurocytoma: report of 2 cases and literature review

Two cases of central neurocytoma are presented. This is a rare CNS tumour affecting, predominantly, young individuals. There is enough evidence in the literature now to distinguish this entity clinically, radiologically and histologically. Much less is known about the management of patients with this tumour, because most of the reports are in pathological literature. Using our two cases and reviewing the available literature, we are endeavouring to shed light on the clinical aspects and management of central neurocytoma. In particular, we attempted to evaluate the role of surgical excision and radiation therapy in the management of this tumour.

An evaluation of abdominal staging procedures performed in pediatric patients with advanced Hodgkin's disease: a report from the Childrens Cancer Study Group

Forty-nine children and adolescents underwent staging laparotomy in the course of a cooperative group (CCG) study of advanced Hodgkin's disease (HD). The purpose of the study was to evaluate the toxicity of a regimen of 12 cycles of doxorubicin, bleomycin, vinblastine, and imidazole carboxamide (ABVD) plus 2,100 cGy regional irradiation in patients with stage III-IV disease. Review of the biopsies and specimens from these 49 laparotomies identified distinct patterns of abdominal involvement and permitted an evaluation of the importance of different aspects of the staging procedure and an assessment of the value of non-invasive techniques in determining the extent of abdominal disease. The major observations from these studies were: (1) computed tomography (CT) and gallium 67 scans (GA) were specific (few false positives), but not sensitive, indicators of abdominal disease; (2) negative findings at laparotomy in 29 patients permitted a contraction of the abdominal radiation fields with no subsequent abdominal recurrence in these patients; (3) in five patients, stage IV status was established only by laparotomy and open hepatic biopsy; (4) all patients with lower abdominal or pelvic involvement also had upper abdominal node or splenic involvement; (5) involvement of splenic hilar nodes was a sensitive predictor of splenic involvement; (6) disease in the inferior paraaortic nodes accurately predicted the presence of more distal disease, ie, in the iliac or pelvic node groups; and (7) in a limited experience, transposition of the ovaries protected ovarian function from the effects of pelvic irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast metastases after bone marrow transplantation for rhabdomyosarcoma

Two adolescent females with metastatic alveolar rhabdomyosarcoma underwent intensive chemoradiotherapy and bone marrow transplantation, one autologous and one allogeneic. Recurrence was detected in the breasts of both patients, the first at autopsy and the other as the only site of treatment failure. Breast masses after bone marrow transplantation should be thoroughly investigated for metastatic disease in patients with rhabdomyosarcoma.

Efficacy and toxicity of 12 courses of ABVD chemotherapy followed by low-dose regional radiation in advanced Hodgkin's disease in children: a report from the Children's Cancer Study Group

Sixty-four patients aged 2 to 18 years with advanced-stage Hodgkin's disease (HD) were treated on a Children's Cancer Study Group (CCSG) pilot toxicity study (521-P). Therapy consisted of 12 courses of Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), bleomycin, vinblastine, and dacarbazine (ABVD), followed by low-dose (2,100 cGy in 12 fractions) regional irradiation (RT). All patients were monitored for toxicity with particular attention to the pulmonary system. Six patients (9%) developed grade 3 or 4 pulmonary toxicity. Three had grade 3 toxicity based solely on changes in carbon monoxide diffusing capacity (DLCO) and remained well for more than 3 years after diagnosis. There was one fatality among the three symptomatic cases. In five cases, toxicity occurred prior to RT. One occurred after seven courses of ABVD, one after nine courses, and three after 10 courses. In one of these five cases, ABVD was stopped. The patient was given nitrogen mustard (mechlorethamine), vincristine, prednisone, and procarbazine (MOPP). This patient subsequently developed recurrence of HD and died of overwhelming sepsis. The other four continued on study and completed their chemotherapy. Three patients had no further bleomycin, and one continued bleomycin at 50% of the assigned dose. They all received mantle RT following chemotherapy, one with a boost dose to the mediastinum to 3,800 cGy and one with added RT to both lungs (1,050 cGy). In the sixth case of pulmonary toxicity, symptoms were first noticed 2 weeks after mantle RT to 3,500 cGy. This patient died of progressive respiratory failure. The event-free survival (EFS) and overall survival is 87% at 3 years. These early results indicate that this therapy is effective in advanced HD in children but has a 9% incidence of acute pulmonary toxicity.

Modification of the 8 drugs in 1 day regimen: feasibility of substitution of other agents

Six children (ages 2 to 14 years) with recurrent or poor risk primary brain tumors were treated with the '8 drugs in 1 day' chemotherapy regimen. As renal function deteriorated (median after five cycles), carboplatin was substituted in place of cisplatin at a median dose of 300 mg/m2 as a one hour infusion at hour three. Four patients also had their lomustine deleted and replaced by etoposide 100 mg/m2 at hour four. Compared to earlier cycles of chemotherapy, there was a moderate increase in transfusion requirement (especially platelets) but the incidences of fever and neutropenia were unchanged. Glomerular function as measured by nuclear glomerular filtration rate (GFR) remained unchanged or improved at the end of therapy. The severity of nausea and vomiting after substitution was markedly improved. Four of the six patients are still in complete remission 19 to 41 months after diagnosis or recurrence. It is feasible to substitute carboplatin and etoposide into the '8 drugs in 1 day' regimen when extramedullary toxicity is found.

The relationship of various aspects of surgical management to outcome in childhood nonmetastatic osteosarcoma: a report from the Childrens Cancer Study Group

Recently, much attention has been focused on the role of adjuvant chemotherapy in the treatment of osteosarcoma. Surgery, however, remains the primary modality for the ablation of this disease. In this report, we examine the relationship of various aspects of surgical management of osteosarcoma to prognosis for disease-free survival (DFS) in a randomized study of 234 pediatric patients. Attention is restricted to 166 patients with nonmetastatic disease confined to an extremity and who were randomized to receive one of two chemotherapeutic regimens. No advantage with respect to DFS was attributable to the various aspects of surgical management considered: interval from first symptoms to definitive surgery, surgical sequence, and type of surgery. Only two local recurrences were seen. One occurred in an above knee amputation stump and the other occurred in a patient receiving a tibial allograft. One of these patients died of pulmonary metastases within 6 months of recurrence; the other patient is alive without evidence of disease at last contact after resection of the recurrence followed by chemotherapy.

Allogeneic bone marrow transplantation using partially-matched related donors

Six patients with advanced leukemia and one with severe combined immunodeficiency syndrome received allogeneic bone marrow transplantation (BMT) from HLA haploidentical donors who were compatible for one or two loci on the non-shared chromosome. Methotrexate was used for prophylaxis against acute graft-versus-host disease (GVHD). All patients engrafted but developed moderate to severe acute GVHD, and three patients died. Two leukemic patients relapsed but two others survived and were free of disease 403 and 936 days post-transplant. BMT using related partially matched donors may result in durable engraftment and long-term survivors. The implications of using such donors in expanding the application of BMT are discussed.

A randomized study comparing high-dose methotrexate with moderate-dose methotrexate as components of adjuvant chemotherapy in childhood nonmetastatic osteosarcoma: a report from the Childrens Cancer Study Group

Methotrexate (MTX) has demonstrated significant activity against relapsed and metastatic osteosarcoma. However, there is little published data to indicate the appropriate dose for MTX when given as a component of a multidrug regimen for the treatment of osteosarcoma. Therefore, the investigators at the Childrens Cancer Study Group undertook a randomized clinical trial that compared Adriamycin and vincristine given with either high-dose methotrexate or moderate-dose methotrexate as postoperation chemotherapy in the treatment of childhood osteosarcoma. We report here the results for 166 patients with completely resected nonmetastatic disease of an extremity. The two therapies demonstrated equivalent disease-free survival (DFS). Further, no therapy prejudices survival after relapse. Approximately 38% of patients remain disease free 4 years after diagnosis. Two relapses occurred in patients free of disease at least 36 months after initiation of treatment. Some factors found by other investigators to be prognostic of poorer DFS, namely, male sex, primary tumor in the humerus or femur, and larger primary tumors, demonstrated similar though not statistically significant trends. The presence of spontaneous necrosis in the tumor sample from the definitive surgery was associated with poor prognosis for DFS. We postulate that this feature represents rapidly growing tumors with increased potential for metastases.

Minoxidil for control of acute blood pressure elevation in chronically hypertensive children

Twenty-three episodes of acute elevation of BP related to renal disease in 13 chronically hypertensive children 2 to 18 years of age were treated with a single oral dose of minoxidil. All except one patient were receiving a diuretic and all but one a beta-blocking agent at the time of minoxidil treatment. The goal of lowering BP to or below the 95th percentile for age within four hours of minoxidil administration was achieved in 14 of 23 treatment episodes. The goal was achieved in nine of 11 (82%) when the dose of minoxidil was greater than or equal to 0.2 mg/kg and in five of 12 (42%) when the dose was less than 0.2 mg/kg (P less than .05). In patients treated with greater than or equal to 0.2 mg/kg of minoxidil, mean systolic and diastolic BP decreased significantly from pretreatment values within one hour. In patients receiving less than 0.2 mg/kg, mean systolic BP was never significantly reduced and mean diastolic BP did not change significantly for two hours. Adverse effects were minimal. The results indicate that minoxidil in a dose of 0.2 mg/kg in combination with a diuretic and beta-blocking agent will lower BP to safe levels in most patients with severe hypertension related to renal disease within four hours with minimal side effects.

Advances in pediatric radiotherapy in the last ten years and future proposals

Advances made can be divided into five main categories. Firstly, the problem of geographic miss which has been reduced by delivering effective radiation doses with greater precision. This has been accomplished with more sophisticated diagnostic and therapeutic equipment, immobilization techniques and computerized treatment planning. Second is the recognition of the interplay of radiation and chemotherapy on normal tissue tolerance and local tumor control. This interaction has necessitated reduction in both dose and volume of irradiation. Third is the use of wide field irradiation as a systemic treatment. Fourthly, the utilization of cooperative group trials to define the role of irradiation. Finally, with the improvement in survival has come the recognition of late effects of irradiation in the growing child and the means of reducing such effects. The current role of radiation therapy in childhood malignancies is summarized, controversies are identified, and future prospects explored.

Primary Ewing's sarcoma of the base of the skull

The authors report a case of primary Ewing's sarcoma of the petrous bone. The radiological features, including the computed tomographic scan and angiographic findings, are described in detail.

Allogeneic bone marrow transplantation for Philadelphia-chromosome positive acute lymphoblastic leukemia

Allogeneic bone marrow transplantation (BMT) produced remission in three patients with Philadelphia-chromosome (Ph1)-positive acute lymphoblastic leukemia (ALL) in relapse. Two patients had remissions which lasted longer than two years. Since the prognosis of Ph1-positive ALL treated with conventional therapy is poor, BMT is indicated in first remission in this disease.

Sudden cerebral death in malignant presacral teratoma

A three-year-old girl with disseminated malignant teratoma was treated by palliative radiotherapy to her pulmonary metastases. She developed seizure followed by absence of cerebral function and death ensued in 36 hours. Computerized scan of brain was negative prior to death. The main finding at autopsy was occlusion of the carotid and cerebral arteries by necrotic tumour. Widespread cerebral tumour embolization may be an unusual terminal event in cancer patients with pulmonary metastases.

Neuroblastoma: influence of age at diagnosis, stage, tumor site, and sex on prognosis

A study of a consecutive series of 99 children with neuroblastoma seen at two major Toronto hospitals between 1951 and 1971 is reported. The children who were aged 24 months or less at diagnosis showed an overall two-year survival rate of 59 percent. Analysis, including fitting of a log-linear model, showed that increased probability of survival was associated with younger age at onset, nonadrenal site, and lower staging and the each of these factors acted independently. The sex of the child had no prognostic effect. This study thus extends earlier work by demonstrating the independent prognostic influence of site of tumor. The implications for treatment policy are discussed.