The LIN28B-let-7-PBK pathway is essential for group 3 medulloblastoma tumor growth and survival

Children with Group 3 medulloblastoma (G3 MB) have a very poor prognosis, and many do not survive beyond 5 years after diagnosis. A factor that may contribute to this is the lack of available targeted therapy. Expression of protein lin-28 homolog B (LIN28B), a regulator of developmental timing, is upregulated in several cancers, including G3 MB, and is associated with worse survival in this disease. Here, we investigate the role of the LIN28B pathway in G3 MB and demonstrate that the LIN28B-lethal-7 (let-7; a microRNA that is a tumor suppressor)-lymphokine-activated killer T-cell-originated protein kinase (PBK; also known as PDZ-binding kinase) axis promotes G3 MB proliferation. LIN28B knockdown in G3-MB-patient-derived cell lines leads to a significant reduction in cell viability and proliferation in vitro and in prolonged survival of mice with orthotopic tumors. The LIN28 inhibitor N-methyl-N-[3-(3-methyl-1,2,4-triazolo[4,3-b]pyridazin-6-yl)phenyl]acetamide (1632) significantly reduces G3 MB cell growth and demonstrates efficacy in reducing tumor growth in mouse xenograft models. Inhibiting PBK using HI-TOPK-032 also results in a significant reduction in G3 MB cell viability and proliferation. Together, these results highlight a critical role for the LIN28B-let-7-PBK pathway in G3 MB and provide preliminary preclinical results for drugs targeting this pathway.

3D genome mapping identifies subgroup-specific chromosome conformations and tumor-dependency genes in ependymoma

Ependymoma is a tumor of the brain or spinal cord. The two most common and aggressive molecular groups of ependymoma are the supratentorial ZFTA-fusion associated and the posterior fossa ependymoma group A. In both groups, tumors occur mainly in young children and frequently recur after treatment. Although molecular mechanisms underlying these diseases have recently been uncovered, they remain difficult to target and innovative therapeutic approaches are urgently needed. Here, we use genome-wide chromosome conformation capture (Hi-C), complemented with CTCF and H3K27ac ChIP-seq, as well as gene expression and DNA methylation analysis in primary and relapsed ependymoma tumors, to identify chromosomal conformations and regulatory mechanisms associated with aberrant gene expression. In particular, we observe the formation of new topologically associating domains ('neo-TADs') caused by structural variants, group-specific 3D chromatin loops, and the replacement of CTCF insulators by DNA hyper-methylation. Through inhibition experiments, we validate that genes implicated by these 3D genome conformations are essential for the survival of patient-derived ependymoma models in a group-specific manner. Thus, this study extends our ability to reveal tumor-dependency genes by 3D genome conformations even in tumors that lack targetable genetic alterations.

Mechanosensitive brain tumor cells construct blood-tumor barrier to mask chemosensitivity

Major obstacles in brain cancer treatment include the blood-tumor barrier (BTB), which limits the access of most therapeutic agents, and quiescent tumor cells, which resist conventional chemotherapy. Here, we show that Sox2⁺ tumor cells project cellular processes to ensheathe capillaries in mouse medulloblastoma (MB), a process that depends on the mechanosensitive ion channel Piezo2. MB develops a tissue stiffness gradient as a function of distance to capillaries. Sox2⁺ tumor cells perceive substrate stiffness to sustain local intracellular calcium, actomyosin tension, and adhesion to promote cellular process growth and cell surface sequestration of β-catenin. Piezo2 knockout reverses WNT/β-catenin signaling states between Sox2⁺ tumor cells and endothelial cells, compromises the BTB, reduces the quiescence of Sox2⁺ tumor cells, and markedly enhances the MB response to chemotherapy. Our study reveals that mechanosensitive tumor cells construct the BTB to mask tumor chemosensitivity. Targeting Piezo2 addresses the BTB and tumor quiescence properties that underlie treatment failures in brain cancer.

Failure of human rhombic lip differentiation underlies medulloblastoma formation

Medulloblastoma (MB) comprises a group of heterogeneous paediatric embryonal neoplasms of the hindbrain with strong links to early development of the hindbrain^1-4. Mutations that activate Sonic hedgehog signalling lead to Sonic hedgehog MB in the upper rhombic lip (RL) granule cell lineage^5-8. By contrast, mutations that activate WNT signalling lead to WNT MB in the lower RL^9,10. However, little is known about the more commonly occurring group 4 (G4) MB, which is thought to arise in the unipolar brush cell lineage^3,4. Here we demonstrate that somatic mutations that cause G4 MB converge on the core binding factor alpha (CBFA) complex and mutually exclusive alterations that affect CBFA2T2, CBFA2T3, PRDM6, UTX and OTX2. CBFA2T2 is expressed early in the progenitor cells of the cerebellar RL subventricular zone in Homo sapiens, and G4 MB transcriptionally resembles these progenitors but are stalled in developmental time. Knockdown of OTX2 in model systems relieves this differentiation blockade, which allows MB cells to spontaneously proceed along normal developmental differentiation trajectories. The specific nature of the split human RL, which is destined to generate most of the neurons in the human brain, and its high level of susceptible EOMES⁺KI67⁺ unipolar brush cell progenitor cells probably predisposes our species to the development of G4 MB.

EPEN-18. Oncogenic 3D genome conformations identify novel therapeutic targets in ependymoma

Ependymoma (EPN) is an aggressive pediatric tumor that occurs throughout the central nervous system. The two most aggressive molecular subgroups of EPN are the supratentorial ZFTA-fusion associated group (ST-EPN-ZFTA) and the posterior fossa group A (PF-EPN-A). Although the molecular characteristics underlying the tumorigenesis of these subgroups have been extensively studied, these tumors remain difficult to treat. Hence, innovative therapeutic approaches are urgently needed. Here, we used genome-wide chromosome conformation capture (Hi-C), complemented with CTCF (insulators) and H3K27ac (active enhancers) ChIP-seq, as well as gene expression and whole-genome DNA methylation profiling in primary and relapsed EPN tumors and cell lines, to identify chromosomal rearrangements and regulatory mechanisms underlying aberrant expression of genes that are essential for EPN tumorigenesis. By integrating these heterogenous data types, we have observed the formation of new topologically associated domains (‘neo-TADs’) caused by intra- and inter-chromosomal structural variants in both tumors. In addition, we observed 3D chromatin complexes of regulatory elements, and the replacement of CTCF insulators by DNA hyper-methylation in PF-EPN-A tumors. These tumor-specific 3D genome conformations can be associated with the transcriptional upregulation of nearby genes. Through inhibition experiments we validated that these newly identified genes, including RCOR2, ITGA6, LAMC1, and ARL4C, are highly essential for the survival of patient-derived EPN cell lines in a disease subgroup-specific manner. Thus, our study identifies novel potential therapeutic vulnerabilities in EPN and extends our ability to reveal tumor-dependency genes and pathways by oncogenic 3D genome conformations even in tumors that lack known genetic alterations.

Modeling human brain tumors in flies, worms, and zebrafish: From proof of principle to novel therapeutic targets

For decades, cell biologists and cancer researchers have taken advantage of non-murine species to increase our understanding of the molecular processes that drive normal cell and tissue development, and when perturbed, cause cancer. The advent of whole-genome sequencing has revealed the high genetic homology of these organisms to humans. Seminal studies in non-murine organisms such as Drosophila melanogaster, Caenorhabditis elegans, and Danio rerio identified many of the signaling pathways involved in cancer. Studies in these organisms offer distinct advantages over mammalian cell or murine systems. Compared to murine models, these three species have shorter lifespans, are less resource intense, and are amenable to high-throughput drug and RNA interference screening to test a myriad of promising drugs against novel targets. In this review, we introduce species-specific breeding strategies, highlight the advantages of modeling brain tumors in each non-mammalian species, and underscore the successes attributed to scientific investigation using these models. We conclude with an optimistic proposal that discoveries in the fields of cancer research, and in particular neuro-oncology, may be expedited using these powerful screening tools and strategies.

A hypothesis: Bitter taste receptors as a therapeutic target for the clinical symptoms of SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has paralysed the livelihood of the global population by inflicting higher mortality among the affected patients. Nearly the entire human physiological system can get disrupted by the virulence of SARS-CoV-2, which exemplifies the significance of discovering a potential drug target. Similar to angiotensin-converting enzyme 2 (ACE2), bitter taste receptors (T2Rs) unequivocally expressed on all vital human organs, particularly on nasal/oral respiratory tract, gastrointestinal organs, innate immune cells, heart, brain and urogenital cells are susceptible to SARS-CoV-2 virulence. Activation of T2Rs by bitter agonists restores vital functions to these organs via activation of large conductance, Ca²⁺-dependent potassium (K⁺) channels (BK_ca), and inducible nitric oxide synthase. T2R activation in the gustatory system can act as the first defence mechanism, primarily preventing or mitigating SARS-CoV-2 entry to the respiratory tract. Moreover, T2R activation is crucial for the improved vasodilation accompanied by the attenuation of systemic inflammation; hyper-innate immune responses; gastrointestinal disorders; defective neurological functions; acute kidney injury; and impotency witnessed in severe SARS-CoV-2 cases. This review discusses the potential for bitter taste receptors to act as drug targets for SARS-CoV-2 symptoms and the use of existing bitter agonists to restore T2R function.

Isolated truncal contrapulsion as a rare presentation of acute thalamic infarct

Infarcts involving the thalamus can yield many deficits, including sensory syndromes, altered consciousness, and cognitive disturbances, depending on the thalamic vascular territory involved. Isolated truncal contrapulsion due to pure thalamic infarct has been rarely reported. Truncal lateropulsion is a compelling sensation of being pulled toward one side that cannot be explained by weakness or limb ataxia. It is commonly reported in lateral medullary infarcts. It may occur with lesions that involve the peripheral vestibular system, brainstem, cerebellum, basal ganglia, ponto-mesencephalic, and thalamic lesions. We hereby report a 64-year-old woman who presented with truncal contrapulsion as the sole manifestation of an acute right lateral thalamic infarct.

Metabolic Regulation of the Epigenome Drives Lethal Infantile Ependymoma

Posterior fossa A (PFA) ependymomas are lethal malignancies of the hindbrain in infants and toddlers. Lacking highly recurrent somatic mutations, PFA ependymomas are proposed to be epigenetically driven tumors for which model systems are lacking. Here we demonstrate that PFA ependymomas are maintained under hypoxia, associated with restricted availability of specific metabolites to diminish histone methylation, and increase histone demethylation and acetylation at histone 3 lysine 27 (H3K27). PFA ependymomas initiate from a cell lineage in the first trimester of human development that resides in restricted oxygen. Unlike other ependymomas, transient exposure of PFA cells to ambient oxygen induces irreversible cellular toxicity. PFA tumors exhibit a low basal level of H3K27me3, and, paradoxically, inhibition of H3K27 methylation specifically disrupts PFA tumor growth. Targeting metabolism and/or the epigenome presents a unique opportunity for rational therapy for infants with PFA ependymoma.

Recurrent noncoding U1 snRNA mutations drive cryptic splicing in SHH medulloblastoma

Recurrent somatic single nucleotide variants (SNVs) in cancer are largely confined to protein coding genes, and are rare in most pediatric cancers^1–3. We report highly recurrent hotspot mutations of U1 spliceosomal small nuclear RNAs (snRNAs) in ~50% of Sonic Hedgehog medulloblastomas (Shh-MB), which were not present across other medulloblastoma subgroups. This U1-snRNA hotspot mutation (r.3a>g), was identified in <0.1% of 2,442 cancers across 36 other tumor types. Largely absent from infant Shh-MB, the mutation occurs in 97% of adults (Shhδ), and 25% of adolescents (Shhα). The U1-snRNA mutation occurs in the 5′ splice site binding region, and snRNA mutant tumors have significantly disrupted RNA splicing with an excess of 5′ cryptic splicing events. Mutant U1-snRNA mediated alternative splicing inactivates tumor suppressor genes (PTCH1), and activates oncogenes (GLI2, CCND2), represents a novel target for therapy, and constitutes a highly recurrent and tissue-specific mutation of a non-protein coding gene in cancer.

SU-E-T-211: Peer Review System for Ensuring Quality of Radiation Therapy Treatments

PURPOSE

To demonstrate a Web-based electronic peer review system that has the potential to improve quality of care for radiation therapy patients. The system provides tools that allow radiation oncologists to seek peer review of target and critical structure delineation, treatment plans, and share clinical data with peers to optimize radiation therapy treatments.

MATERIAL AND METHODS

Peer review of radiation therapy treatment planning data prior to its initiation improves the quality of radiation therapy and clinical outcomes. Web-based access to radiation therapy treatment planning data and medical records mitigate existing geographical and temporal constraints. With internet access, the healthcare provider can access the data from any location and review it in an interactive and collaborative manner. Interoperability standard like DICOM-RT and IHE-RO compliant RT Systems have facilitated the design and implementation of PRS with Silverlight Web technology, .net Framework and SQL Server. Local DICOM-RT archive and cloud based services are deployed to facilitate remote peer reviews.

RESULTS

To validate the PRS system, we tested the system for 100 patients with Philips Pinnacle v 9.0 and Varian Eclipse v 8.9 treatment planning system (TPS). We transmitted the DICOM RT data from the TPS to the cloud based services via the PRS local DICOM RT Archive. Various CT simulation based parameters such as orientation of CT, properties of RT structures etc. were compared between the TPS and PRS system. Data integrity of other parameters such as patient demographics (patient name, ID, attending physician etc.) and dose volume related parameters were also evaluated. Such rigorous testing allowed us to optimize the functionalities and clinical implementation of the PRS.

CONCLUSIONS

We believe that the PRS will improve the quality and safety of a broad spectrum of radiation therapy patients treated in underserved areas while discouraging the overutilization of expensive radiation treatment modalities. This research and development project is supported by the James and Ester King Biomedical Research Program grant # RC1-09KW-09-26829.

Analysis of Indian blue ballpoint pen inks tagged with rare-earth thenoyltrifluoroacetonates by inductively coupled plasma–mass spectrometry and instrumental neutron activation analysis

Characterization and assessment of inks on sensitive documents for absolute/relative age determination is the challenging forensic problem in spite of practical difficulties. Tagging of ballpoint pen ink with suitable taggant(s) is a unique method to come out with definitive inferences on the detection of forgery in documents written with ballpoint pens. Selection of a proper taggant primarily depends on sensitivity of analytical determination and their absence in normal varieties of ink used for document writing. Rare-earth elements, from all technical considerations can be potential taggant(s) for inks. To ensure more compatibility with ink, 13 rare-earth thenoyltrifluoroacetonate chelates were prepared and characterized. The ballpoint pen inks were tagged with rare-earth thenoyltrifluoroacetonate chelates individually at about 1-100 ppm level depending on sensitivity of element under suitable optimized experimental conditions and instrumental sensitivity. Aliquots of such tagged ink having varying amounts of taggants were analyzed by ICP-MS and INAA. Satisfactory recoveries and a good linear relationship of intensity (signal) against concentrations/amounts were observed. Under the optimized experimental conditions, the detection limits were worked out. This study of tagging metal ions in combination with ICP-MS and NAA as an analytical tool can allow to draw various combination options based on different rare-earth chelates as suitable materials for tagging of ballpoint pen inks for absolute/relative age determination to aid in document related crime examination. The advantages and limitations of proposed analytical techniques are discussed.

Recurrent acute renal failure in a patient with minimal change disease

We report on a 16-year old female patient with biopsy proved minimal change disease and steroid state. She was subsequentlygiven cyclosporin for varying periods of time with inadequate response. She developed four episodes of acute renal failure in the background of severe nephrotic state, 10 years after the onset of her illness. Three of these episodes could be reversed with albumin infusion and judicious use of diuretics while the fourth necessitated six sessions of ultrafiltration. In none of the episodes of ARF could we find any cause other than the nephrotic state itself.

Simplified Surgical Placement of Tenckhoff Catheter under Local Anesthesia: The Dammam Central Hospital Experience

Many methods are used for the placement of Tenckhoff catheters. Eighteen consecutive Tenckhoff catheters were placed under local anesthesia through a mini laparotomy with a reduced operating team. There were only three total catheter failures. Complications were infrequent and operating time was less than one hour on average. This simple procedure should be a part of the training program of all junior surgeons and nephrologists.

Study of low productive value of rapid survey as a means of leprosy case detection in Kanpur urban project

A study was undertaken in Kanpur city to identify the reasons for low yield of rapid survey in leprosy case detection and to intervene to overcome the shortcomings. By a random cluster sampling method, 200,000 persons were selected for the study. Rapid survey was undertaken in half the area and in another half similar survey was undertaken after additional inputs. The additional inputs were staff training, IEC activities, changing of the survey timings and addition of a female worker to the survey teams. The proportion of the population enumerated population showed a significant rise (from 58.35% to 72.21%) in the test area with additional inputs. The number and the type of cases detected did not show any difference. Significantly, addition of female workers to the team did not improve the proportion of the female population examined or of female cases detected.

Novel C-ring analogues of 20(S)-camptothecin. Part 3: synthesis and their in vitro cytotoxicity of A-, B- and C-ring analogues

Several 5-substituted alkoxy 20(S)-camptothecin analogues having A- and B-ring substituents were prepared via semi-synthesis. Most of these compounds were found to exhibit potent anti-cancer activity based on their in vitro cytotoxicity data obtained against human tumor cell lines.

Novel C-ring analogues of 20(S)-camptothecin-part-2: synthesis and in vitro cytotoxicity of 5-C-substituted 20(S)-camptothecin analogues

A series of 5-C-substituted 20(S)-camptothecin analogues were synthesised and evaluated their in vitro anti-cancer activity. Several of these analogues have showed excellent activity against human tumor cell lines.

Urticaria and angioedema: diagnostic and treatment considerations

Urticaria and angioedema are common--and commonly frustrating--problems for physicians and patients alike. Patients often are in considerable distress with pruritus and uncomfortable lesions. They are frightened about their condition and frustrated when modern medicine cannot pinpoint the cause of the symptoms. Both urticaria and angioedema may be categorized as acute and chronic conditions. The dividing line between acute and chronic forms is relatively arbitrarily set at 6 weeks. A thorough history and physical examination may provide clues to the underlying cause, but in the majority of patients, the cause is rarely identified. One is more likely to discover the cause of acute than of chronic urticaria. A multitude of laboratory tests can be performed, but they often do not provide a diagnosis. It is not appropriate to do a large "screening" battery of laboratory tests. The dermal mast cells and their mediators play a central role in chronic urticaria. Chronic urticaria may have an autoimmune aspect. Recent evidence reveals that 50% of patients with chronic urticaria have a cutaneous autoimmune disorder mediated by autoantibodies to the high-affinity IgE receptor on mast cells. Biopsy may be necessary and may help with treatment.

Comparative incidence of the rearrangements of TEL/AML1 and ALL1 genes in pediatric precursor B acute lymphoblastic leukemias in India

The TEL/AML1 translocation, which is specific for pre B-cell leukemias is predictive of a favorable treatment outcome. In contrast, translocations involving the ALL1 locus which are associated with both B and non B leukemias predict a poor outcome. To determine the relative distribution of high and low risk molecular subtypes of ALL in India, we analyzed the relative frequencies of these two translocations. The study included a random selection of 46 newly diagnosed patients of childhood ALL from the Tata Memorial Hospital, Bombay, India. Similar to the frequency observed in other world regions, we found an All1 rearrangement in less than 7% (3/46) of pre B-ALL patients. In contrast to the 25% frequency reported for other regions the low risk molecular subtype characterized by the TEL/AML1 translocation represented a comparatively smaller fraction (4/46) in this study. These results provide a preliminary support for a lower frequency of molecular subgroup of leukemias with a potential for favorable clinical outcome in precursor B-ALL from India.

Multilayer antireflection coatings for the visible and near-infrared regions

With a high-refractive-index mixed-oxide dielectric material of ZrTiO(4) and ZrO(2) [Substance H2 (Sub2) from E. Merck, Darmstadt, Germany], in combination with magnesium flouride (MgF(2)), design optimization and experimental production of low-loss antireflection (AR) coatings are carried out. Design-optimization studies that make use of these materials as constituents of a seven-layer coating system demonstrate that when the useful bandwidth of an AR coating is extended to cover a wider spectral range, the designs are in general found to have increased integrated reflection loss, higher ripple, and increased spectral instability. The experimental studies on Sub2 material show that the films have excellent optical performance over a wider process window, the advantage of which is demonstrated in the production of different AR coatings on a variety of glasses with refractive indices that range from 1.45 to 1.784 and different mechanical, thermal, and chemical properties. The manufacturing process of AR coatings shows a consistency better than 99% with respect to optical properties and durability.

Transcriptional regulation of surfactant proteins SP-A and SP-B by phorbol ester

Phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) activate protein kinase C and have been previously shown to down-regulate surfactant proteins SP-A and SP-B in H441 adenocarcinoma cells. We used H441 cells and human fetal lung to further study the mechanism of TPA action and to examine physiologic relevance. In H441 cells, TPA (10 nM) treatment for 24 h decreased SP-A mRNA content to approximately 5% of control cells, with half-maximal effect at approximately 0.5 nM, and reduced SP-A gene transcription rate to 28% of control after 8 h exposure. In cells cultured in the presence of dexamethasone, which increases the low basal level of SP-B expression, TPA decreased both SP-B mRNA content (approximately 8% of control) and rate of transcription (7% of control). In cultured human fetal lung explants, TPA decreased SP-A and SP-B protein and mRNA in a time- and dose-dependent fashion, with half-maximal effect on mRNAs at approximately 3 nM and approximately 50% inhibition after 24 h of exposure, and similarly reduced SP-A and SP-B gene transcription (approximately 55% of control at 8-24 h). We conclude that TPA acts primarily at the level of gene transcription to down-regulate both SP-A and SP-B in H441 and fetal lung cells, and we speculate that inflammatory and other agents that act through PKC may modulate expression of the surfactant proteins and alter surfactant function in vivo.

Low-reflection-loss attenuator optical coatings: theory and experiment

Following the optical admittance matching approach, we have derived explicit equations to evaluate the refractive index and thickness of the matching dielectric layer deposited on an attenuator layer to obtain zero or near-zero reflection loss at one or more than one wavelength. With these equations a new family of optical coatings that can not only attenuate the input optical radiation to a required level but can also show a very low reflection loss (less than 0.1%) within a specified band is successfully designed and developed. Typical coatings, produced by electron-beam evaporation, have an average reflection loss of less than 1% and transmittance of 0.42 and 0.64 ± 0.02 over visible and near-IR spectral regions, respectively.

Uterine atrophy in chronic murine toxoplasmosis due to ovarian dysfunction

Uterine atrophy is a conspicuous finding in Nya:NYLAR female mice chronically infected with Toxoplasma gondii. Administration of 17B-estradiol to infected mice induced a vigorous uterotropic response, i.e., an increase in uterine weight, in endometrial hypertrophy and proliferation, and in the activity of three estrogen-regulated uterine enzymes. These findings rule out a parasite-induced refractoriness of the uterus to estrogen and point to ovarian dysfunction (hypogonadism) as the immediate cause of the uterine atrophy.

Estrogen regulation of creatine kinase-B in the rat uterus

Creatine kinase-B (CKB) synthesis is rapidly and specifically induced by estrogen in the uterus of the immature rat. This study indicates that this elevation is due at least in part to increases in the levels of mRNA for CKB. The stimulation of CKB mRNA levels is rapid (a 7- to 10-fold increase is detected 1-3 h after estrogen administration), but transient, as levels return to near control values by 6 h. Analysis of cDNAs to both uterine and brain CKB mRNA indicate that the same sequence is expressed in both tissues despite earlier observations of heterogeneity of the protein isolated from the two tissues. A 1.7-kilobasepair DNA fragment containing the CKB promoter and 5' flanking sequences confers estrogen sensitivity on expression of the bacterial chloramphenicol acetyl transferase gene in HeLa cells on cotransfection with an estrogen-receptor expression vector. However, the CKB promoter sequences lack any motif with convincing similarity to the currently accepted consensus estrogen response element GGTCAnnnTGACC.

Estrogen regulation of human breast cancer cell line MCF-7 tissue plasminogen activator

The human breast cancer cell line MCF-7 produces a number of estrogen-regulated proteins, among which is tissue plasminogen activator (tPA). Increased medium concentrations of PA activity were observed after the addition of 17 beta-estradiol to cultures of MCF-7 cells. However, in the current study these hormone-regulated increases are limited to cultures near or at confluence, but not in the preconfluent period. MCF-7 cell cultures produce either tPA activity alone or in combination with urokinase activators. At confluence, a single exposure to 17 beta-estradiol stimulates a marked transitory rise in tPA activity in the extracellular and cell-associated compartments; the peak increases were at 48 h for medium activity and 24-48 h for cell-associated activity. Sustained exposure to hormone leads to a persistent increase in activity in both compartments. Examination of the structure-function relationships of estrogen agonists, steroidal and nonsteroidal, as well as nonestrogenic steroids indicated that stimulation of PA activity was restricted to estrogen agonists. The increased activity was reflected in enhancement of tissue PA activity when viewed using sodium dodecyl sulfate-polyacrylamide gel zymography. Those cultures expressing both activators revealed no alteration of urokinase activity due to hormone addition. Antiestrogens added to MCF-7 cells not rigorously limited in exogenous estrogens selectively suppressed tissue PA activity, but not that of urokinase. These data indicate that at the point when MCF-7 cell cultures are no longer growing exponentially, addition of estrogen agonists at physiological concentrations elevates tPA activity while not altering expression of urokinase activity. The discussion suggests a possible role that this regulation may subserve in the function of breast epithelial cells.

Suppression of estrogen-regulated extracellular tissue plasminogen activator activity of MCF-7 cells by 2,3,7,8-tetrachlorodibenzo-p-dioxin

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) suppresses the estrogen enhancement of tissue plasminogen activator (t-PA) by MCF-7 breast cancer cells. 17 beta-estradiol treatment of MCF-7 cells was previously shown to enhance t-PA secretion in a receptor-mediated process dependent on RNA and protein synthesis. The current studies demonstrate that treatment with TCDD, at a concentration as low as 10(-11) M, reduces the 17 beta-estradiol-induced enhancement of t-PA secretion in these cells. Treatment of MCF-7 cells with TCDD alone does not alter t-PA activity nor was inhibition of t-PA activity observed when TCDD was added directly to the enzyme assay. Kinetic studies and the lack of inhibition following in vitro mixing of conditioned media from TCDD-treated and control 17 beta-estradiol stimulated MCF-7 cells argue against TCDD induction of a plasminogen activator inhibitor. The related polychlorinated dibenzofuran, 2,3,7,8,-tetrachlorodibenzofuran, while also active, is less potent that TCDD. Other polychlorinated dibenzodioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls do not suppress 17 beta-estradiol induction of t-PA over the concentrations tested. These results are in agreement with the structure-activity relationships established using these compounds in other assay systems. Treatment with TCDD does not alter the number or affinity of 17 beta-estradiol receptors of MCF-7 cells. TCDD treatment does not suppress constitutive t-PA activity in the estrogen independent breast cancer line MDA-MB-231 nor the t-PA induced by 12-O-tetradecanoylphorbol-13-acetate in HeLa cells. These effects suggest that TCDD is not acting directly on expression of the t-PA genome. Induction of aryl hydrocarbon hydroxylase by TCDD, a cytochrome P-450 regulated metabolic enzyme for which TCDD is the most potent known inducer, was observed in MCF-7 cells but not in MDA-MB-231 or HeLa cells. A plausible mechanism for the antiestrogenic activity of TCDD is based on the metabolic conversion of 17 beta-estradiol to less active derivatives by TCDD induced cytochrome P-450 metabolic enzymes.

Induction of creatine kinase in immature rat uteri by zearalenone, an estrogenic mycotoxin

Intraperitoneal administration of alpha-zearalenone (ZEN) to female immature rats induced synthesis of a uterine protein which has been identified as creatine kinase. The induced enzyme was purified to homogeneity by chromatography on DEAE Sephacel and Hydroxyapatite Ultrogel. Guinea pig antiserum against estrogen-induced uterine, rat uterine creatine kinase crossreacted with the ZEN-induced enzyme, indicating that ZEN exhibits an early estrogenic response in a manner analogous to natural estrogens.

Comparative analysis of rat uterine estrogen-induced creatine kinase with monoclonal antibodies

Monoclonal antibodies were generated against rat uterine estrogen-induced protein--creatine kinase (CK-EIP)--and two (MAb-28 and MAb-78) were studied. These antibodies were IgM but differed in their complementary antigenic determinants both of which were detectable on denatured but not on native CK-EIP. MAb-28 reacted with other CK-BBs but not with CK-MMs whereas MAb-78 reacted with both types of CKs. A measurement of antigenicity with the monoclonal antibodies under calibrated conditions showed differences among the CKs, notably between CK-BB from rat brain and CK-EIP when both were probed with MAb-28. The antigenicity of CK-BB (rat brain) was significantly lower than that of CK-EIP, indicating that the former either expresses less copies of the determinant recognized by MAb-28 than CK-EIP does, or possesses a determinant which interacts with the antibody with lower affinity. The monoclonal antibodies should help elucidate structure-function relationships in CK-BB and CK-EIP molecules, their anatomic distribution and their physiologic, pathologic and experimental variations in relation to gene expression induced by sex hormones.

Estradiol preferentially enhances extracellular tissue plasminogen activators of MCF-7 breast cancer cells

MCF-7 human breast cancer cells secrete two immunologic types of plasminogen activator, one related to urokinase, the other unrelated. We have now examined whether estrogen stimulation of secreted plasminogen activator activity reflects an increase in one or both types. Examined semiquantitatively by sodium dodecyl sulfate-polyacrylamide gel electrophoretic zymography, the conditioned media of control cells were seen to contain a major activator band (Mr approximately 54,000) immunologically related to urokinase and a barely discernible doublet (Mr approximately 64,000 and Mr approximately 68,000). Addition of estradiol or, at much higher concentrations, testosterone led to marked enhancement of doublet activity, while the 54-kDa band was invariant. The 64-68-kDa doublet was immunoreactive with antiserum directed against Bowes melanoma tissue plasminogen activator but not with antiurokinase antibodies. Enhancement of doublet activity was correlated with hormone-induced increases in total secreted plasminogen activator activity. Neither progesterone nor dexamethasone increased total activity or the 64-68-kDa zones of lysis. Estradiol and testosterone alterations were blocked by appropriate concentrations of an estrogen antagonist (LY156758), actinomycin D, or cycloheximide. Regulation of MCF-7 cell-secreted tissue plasminogen activators thus appears to be mediated by an estrogen receptor process and to require sustained RNA and protein synthesis.

Nonspecific esterases of leukemia cell lines: evidence for activation of myeloid-associated zymogens in HL-60 by phorbol esters

Myeloid leukemia cell line HL-60 contains fluoride-sensitive, myeloid-associated isoenzymes of nonspecific esterase that increase in activity when cultures are treated with phorbol ester. These isoenzymes are not detectable in B-lymphoblast cell line KLM-2, either in control or in phorbol-ester-treated cultures. No increased de novo synthesis of the isoenzymes is detectable in HL-60 treated with phorbol ester. The data suggest stimulated conversion of a preformed, myeloid-associated zymogen in HL-60.

Reversal of diabetic nephropathy in human cadaveric kidneys after transplantation into non-diabetic recipients

Two kidneys were removed from a cadaveric donor with 17-year history of type 1 diabetes. At the time of death the donor had proteinuria but normal serum creatinine, and on histological examination the kidneys showed features of established diabetic nephropathy including diffuse glomerulosclerosis and thickening of mesangial matrix and capillary basement membranes. After transplantation into non-diabetic recipients (cold ischaemia times 46 h and 52 h) the kidneys functioned well with standard immunosuppression. Renal biopsy specimens taken 7 months after transplantation showed almost complete resolution of the nephropathy and both patients remain free from proteinuria after a further 7 months. As well as indicating that longstanding type 1 diabetes need not always contraindicate kidney donation, these observations are relevant to the pathogenesis and management of diabetic nephropathy.

Inhibition of DNA-dependent RNA polymerase from Escherichia coli by pyran copolymer

Pyran copolymer, a potent inhibitor of DNA-dependent RNA polymerase from Escherichia coli, prevented polyribonucleotide synthesis by blocking both the initiation and elongation steps. The inhibition was noncompetitive with respect to template and nucleotide triphosphate substrates. Template binding and the stability of the nascent RNA chain were not affected by the inhibitor.

Myocardial contusion following nonfatal blunt chest trauma

Currently available diagnostic techniques for myocardial contusion following blunt chest trauma were evaluated. We investigated 30 patients prospectively over a period of 1 year for the presence of myocardial contusion. Among the 30 patients, eight were found to have myocardial contusion on the basis of abnormal electrocardiograms, elevated creatine phosphokinase MB fraction (CPK-MB), and positive myocardial scan. Myocardial scan was positive in seven of eight patients (87.5%). CPK-MB fraction was elevated in four of eight patients (50%). Definitive electrocardiographic changes were seen in only two of eight patients (25%). It appears that myocardial scan using technetium pyrophosphate and CPK-MB fraction determinations are the most reliable aids in diagnosis of myocardial contusion following blunt chest trauma.

Purification and characterization of creatine kinase, an estrogen-induced uterine protein (IP) from immature rats

An estrogen-responsive translational product, the induced protein (IP) first described by Notides and Gorski (8), was obtained solely from the target organ, immature rat uterus, and purified to homogeneity in a procedure using two chromatography steps. The purified IP has a molecular weight of 49,000, and the isoelectric point is 5.2. Creatine kinase activity is associated with the homogeneous IP. There are some differences between the uterine enzyme and the creatine kinase BB isoenzyme, including differences in stability, and sensitivity to mercaptans. Estrogen-induced creatine kinase purified by this simple, reproducible method is a useful antigen for further studies on the translation and transcription processes involved in hormone-modulated synthesis.

Oligodeoxynucleotide base recognition by steroid hormone receptors

Oligodeoxynucleotides covalently linked to cellulose were used as probes of the DNA-binding domains of mouse steroid holoreceptors. With uterine cytosol estrogen receptor (E2R) the relative binding order, in prior studies, was oligo(dG) greater than oligo(dT) greater than or equal to oligo(dC) much greater than oligo(dA) greater than oligo(dI). The binding reactions were salt-sensitive with an optimal KCl concentration of 0.1-0.2 M. There was no enhancement of binding by activation, either temperature- or salt-induced. In the present study, using the oligomer ligands at a lower concentration, oligo(dT) binding was greater than that to oligo(dC). Quantitative differences in oligodeoxynucleotide binding were elicited by a number of inhibitors. These differences are again seen by exposure of E2R to chaotropic salts such as SCN-, ClO-4 and NO3- as well as to putative modifiers of receptor amino acids, ie, iodoacetamide, 1,2 cyclohexanedione, and Rose Bengal. These results, and the quantitative differences following heat and purification, led to a designation of two types of subsites within the DNA-binding domain of uterine E2R. These are stable G sites, which interact with oligo(dG); and labile N sites, which bind to oligo(dT), oligo(dC) and oligo(dA). Stimulation of binding to N sites and stabilization of the holoreceptor was effected by histones H2A and H2B. However, the differential response to incubation at 37 degrees C was not altered by addition of H2B. Treatment of uterine E2R by limited proteolysis also eliminated the stimulatory response to H2B. The above data, as well as prior studies, indicate that steroid holoreceptors can discriminate between the structural features of deoxynucleotide bases and this recognition process can be modulated by accessory proteins.

Immobilized oligodeoxynucleotides as probes of the DNA-binding sites of mouse steroid holoreceptors

Steroid hormone receptors are DNA-binding proteins with distinct domains for the steroid ligand and for polydeoxyribonucleotides. The characteristics of the polynucleotide-binding sites of the mouse liver dexamethasone receptor, kidney testosterone and estradiol receptors, and uterine estradiol receptor were examined by using oligodeoxynucleotides covalently linked to cellulose as probes. Only dexamethasone receptor binding to oligodeoxynucleotides was dependent upon activation by increased salt concentrations or temperature. The dexamethasone and estradiol receptors required a distinct concentration of KCl for maximal binding to oligodeoxynucleotide-cellulose. In contrast, binding of mouse kidney testosterone receptor was not stimulated by KCl although it was decreased at 0.2 M KCl. The nucleotide affinities of the mouse receptors generally followed the order of binding to oligo(dG)- greater than oligo(dT)- greater than oligo(dC)- greater than oligo(dA)-cellulose. However, the liver dexamethasone receptor bound to oligo(dT)- more avidly than to oligo(dC)-cellulose, while neither the testosterone nor the estradiol receptors clearly differentiated between the oligodeoxypyrimidine celluloses. Although the binding of the kidney testosterone receptor was poorest of those studied, it bound to oligo(dA)-cellulose relatively more efficiently than did the other steroid receptors. Thus, differences were revealed in the requirements for activation, added salt for binding, and relative binding efficiencies to the ligands among different steroid receptors from the same tissue and among the same steroid receptors from different tissues.

The polynucleotide binding sites of estradiol receptor complexes

As a model for interaction of steroid receptors with DNA, the binding of estradiol receptor complexes (E2R) to oligodeoxynucleotides, covalently linked to cellulose, was studied in detail. Binding was optimal at concentrations of monovalent cationic salts at, or near, isotonic levels and was selective for intracellular receptors in contrast to extracellular steroid binding proteins. Among the oligomers, the order of affinity was oligo dG greater than oligo dT greater than oligo dC greater than oligo dA greater than oligo dI. The binding to oligo dG was stable to 37 degrees C exposure and the processes of adsorption and desorption, while reactivity with oligo dT, oligo dC and oligo dA was labile. The decrease in binding following purification was restored by histone 2B. Oligo dG binding was the most resistant to inhibition by cibacron blue F3GA (CB) and pyridoxal-5-phosphate. On the basis of these data, a hypothesis is proposed for the interaction of mouse uterine cytosol E2R with prevalent nonspecific and putative specific sequences of DNA.

Diethylpyrocarbonate inhibition of estradiol receptor binding to oligonucleotides

Exposure of calf uterine estradiol-receptor complexes to diethylpyrocarbonate (ethoxyformic anhydride) at pH 6.3-6.5 results in a decrease in the ability of the receptor to bind to oligodeoxyribonucleotides. The inhibition of binding to oligodeoxypyrimidines is greater than the inhibition of binding to oligodeoxyguanylate. The inhibition by 6.6 mM diethylpyrocarbonate is complete within 10 min at 4 degrees C. Addition of equimolar quantities of histidine or imidazole prior to exposure to diethylpyrocarbonate prevents subsequent inhibition of oligodeoxyribonucleotide binding. In comparison to histidine, other amino acids tested were deficient in this ability. Diethylpyrocarbonate modification of the receptor causes complete loss of oligodeoxyribonucleotide binding activity at times when there is a loss of less than 20% of bound steroid. Pyridoxal 5'-phosphate treatment of receptor does not prevent subsequent modification by diethylpyrocarbonate, suggesting that the site of reaction is not an essential lysine of the DNA-binding domain. Treatment of the ethoxyformylated receptor with 0.45 M hydroxylamine results in recovery of 70% of the receptor's oligonucleotide-binding ability. The time course of the reaction of diethylpyrocarbonate with the estradiol receptor and the demonstration of hydroxylamine reversal of inhibition suggest that histidine is involved in the binding of estradiol receptor to oligodeoxyribonucleotides.

Specificity of oligodeoxynucleotide binding of mouse uterine cytosol estradiol receptors

The relative capacities of oligodeoxynucleotides, covalently linked to cellulose, to bind estradiol receptor complexes (E2R) of mouse uterine cytosol have been shown to follow the order oligo(dG) > oligo(dT) greater than or equal to oligo(dC) > oligo(dA). The E2R . oligo(dT)-cellulose-binding reaction is more sensitive to Cibacron blue F3GA than is E2R . oligo(dG)-cellulose or oligo(dC)-cellulose binding. Preformed E2R . oligo(dT)- or oligo(dC)-cellulose complexes are dissociated more readily by lower concentrations of KCl or Cibacron blue F3GA than is the E2R . oligo(dG)-cellulose complex. Preincubation of E2R at 37 degrees C results in a rapid loss of binding ability towards oligo(dT)- and oligo(dC)-cellulose, while up to 90% of the binding ability to oligo(dG)-cellulose is retained. On the basis of the differential sensitivities of E2R to temperature and the inhibition by Cibacron blue F3GA of the binding reaction, it is suggested that the polynucleotide-binding domain consists of two types of subsites, one of which has a higher affinity for oligo(dG) residues and the other of which recognizes oligo(dT), oligo(dC), and, to a lesser extent, oligo(dA).