Metabolic remodeling of bacterial surfaces via tetrazine ligations

Bioorthogonal click ligations are extensively used for the introduction of functional groups in biological systems. Tetrazine ligations are attractive in that they are catalyst-free and display favorable kinetics. We describe the efficient remodeling of bacterial cell surfaces using unnatural d-amino acids derivatized with tetrazine ligation handles. The metabolic incorporation of these unnatural d-amino acids onto bacterial cell surfaces resulted in a site-selective installation of fluorophores.

Scaffold hopping approach on the route to selective tankyrase inhibitors

A virtual screening procedure was applied to identify new tankyrase inhibitors. Through pharmacophore screening of a compounds collection from the SPECS database, the methoxy[l]benzothieno[2,3-c]quinolin-6(5H)-one scaffold was identified as nicotinamide mimetic able to inhibit tankyrase activity at low micromolar concentration. In order to improve potency and selectivity, tandem structure-based and scaffold hopping approaches were carried out over the new scaffold leading to the discovery of the 2-(phenyl)-3H-benzo[4,5]thieno[3,2-d]pyrimidin-4-one as powerful chemotype suitable for tankyrase inhibition. The best compound 2-(4-tert-butyl-phenyl)-3H-benzo[4,5]thieno[3,2-d]pyrimidin-4-one (23) displayed nanomolar potencies (IC50s TNKS-1 = 21 nM and TNKS-2 = 29 nM) and high selectivity when profiled against several other PARPs. Furthermore, a striking Wnt signaling, as well as cell growth inhibition, was observed assaying 23 in DLD-1 cancer cells.

Larvicidal activity of Brazilian plant essential oils against Coenagrionidae larvae

Odonate larvae can be serious pests that attack fish larvae, postlarvae, and fingerlings in fish culture tanks, causing significant loss in the supply and production of juveniles. This study reports a screen of the essential oils (EOs) of Nectandra megapotamica (Sprengel) Mez, Nectandra grandiflora Nees, Hesperozygis ringens (Bentham) Epling, Ocimum gratissimum L., Aloysia gratissima (Gillies & Hooker) Troncoso, and Lippia sidoides Chamisso against Coenagrionidae larvae. In addition, the most effective EO and its 50% lethal concentration (LC50) and chemical analysis are described. The larvae of Acanthagrion Selys, Homeoura Kennedy, Ischnura Charpentier, and Oxyagrion Selys were used to assess the EO effects. EO obtained from H. ringens, O. gratissimum, and L. sidoides showed the highest larvicidal effects at 19 h of treatment. The major constituents of the EO of H. ringens include pulegone and limonene, while eugenol and Z-beta-ocimene predominate in the EO of O. gratissimum, and carvacrol and rho-cymene were the major compounds of the EO of L. sidoides. Leaf EOs from H. ringens, O. gratissimum, and L. sidoides showed activity against Coenagrionidae larvae at similar concentrations with LC50s of 62.92, 75.05, and 51.65 microl liter(-1), respectively, and these were considered the most promising treatments.

Alterations of EGFR, p53 and PTEN that mimic changes found in basal-like breast cancer promote transformation of human mammary epithelial cells

Breast cancer can be classified into different molecular subtypes with varying clinical and pathological characteristics. The basal-like breast cancer subtype represents one of the most aggressive and lethal types of breast cancer, and due to poor mechanistic understanding, it lacks targeted therapy. Many basal-like breast cancer patient samples display alterations of established drivers of cancer development, including elevated expression of EGFR, p53 inactivating mutations and loss of expression of the tumor suppressor PTEN; however, their contribution to human basal-like breast cancer pathogenesis remains ill-defined. Using non-transformed human mammary epithelial cells, we set out to determine whether altering EGFR, p53 and PTEN in different combinations could contribute to basal-like breast cancer progression through transformation of cells. Altering PTEN in combination with either p53 or EGFR in contrast to any of the single alterations caused increased growth of transformed colonies in soft agar. Concomitantly modifying all three genes led to the highest rate of cellular proliferation and the greatest degree of anchorage-independent colony formation. Results from our effort to engineer a model of BBC expressing alterations of EGFR, p53 and PTEN suggest that these changes are cooperative and likely play a causal role in basal-like breast cancer pathogenesis. Consideration should be given to targeting EGFR and restoring p53 and PTEN signaling simultaneously as a strategy for treatment of this subtype of breast cancer.

The nested assembly of individual-resource networks

1. Much of the current understanding of ecological systems is based on theory that does not explicitly take into account individual variation within natural populations. However, individuals may show substantial variation in resource use. This variation in turn may be translated into topological properties of networks that depict interactions among individuals and the food resources they consume (individual-resource networks). 2. Different models derived from optimal diet theory (ODT) predict highly distinct patterns of trophic interactions at the individual level that should translate into distinct network topologies. As a consequence, individual-resource networks can be useful tools in revealing the incidence of different patterns of resource use by individuals and suggesting their mechanistic basis. 3. In the present study, using data from several dietary studies, we assembled individual-resource networks of 10 vertebrate species, previously reported to show interindividual diet variation, and used a network-based approach to investigate their structure. 4. We found significant nestedness, but no modularity, in all empirical networks, indicating that (i) these populations are composed of both opportunistic and selective individuals and (ii) the diets of the latter are ordered as predictable subsets of the diets of the more opportunistic individuals. 5. Nested patterns are a common feature of species networks, and our results extend its generality to trophic interactions at the individual level. This pattern is consistent with a recently proposed ODT model, in which individuals show similar rank preferences but differ in their acceptance rate for alternative resources. Our findings therefore suggest a common mechanism underlying interindividual variation in resource use in disparate taxa.

Abstract PD03-05: A Novel Combination Therapy for Triple Negative Breast Cancer: Erlotinib and Metformin

Background: Triple negative breast cancer (TNBC) is defined by lack of expression of estrogen, progesterone and HER2 receptors and accounts for approximately 15% of breast cancer. TNBC patients have a poor prognosis and novel therapies are needed. The majority of TNBC are basal-like tumors that overexpress the epidermal growth factor receptor (EGFR). However, clinical use of EGFR inhibitors has yielded disappointing results likely due, in part, to downstream driving mutations including PTEN. TNBC occurs more frequently in type II diabetic patients indicating that aberrations in glucose metabolism may contribute to TNBC development. The type II diabetes drug metformin has been associated with a decreased incidence of breast cancer and enhanced response to chemotherapy. In this study, we explored the combined effect of erlotinib (an EGFR kinase inhibitor) and metformin on TNBC.

Results and Methods: Using the TNBC cell lines MDA-MB-468 and BT549 with known p53 mutation, PTEN mutation and EGFR expression, we observed the novel combination of metformin and erlotinib potently induced cell death in these TNBC cell lines in a 6-day proliferation assay. Using metformin or erlotinib alone at the same doses partially inhibited growth but was unable to induce cell death. In a cytotoxic clonogenic assay, erlotinib combined with metformin significantly suppressed formation of colonies compared with either drug alone, and compared with the TORC1 inhibitor rapamycin combined with erlotinib or metformin. In addition, as compared with control MCF10A cells (an immortalized nontransformed human mammary epithelial cell line), the combined treatment preferentially induced cell death in an MCF10A cell line modified with PTEN loss, expression of dominant negative p53 and increased expression of EGFR. Again, cell death was not observed when either drug was used alone. We showed through western blots that erlotinib as a single agent is very effective in down-regulating the activity of the MAPK pathway but is less effective in down-regulating the activity of the PI3K pathway. We demonstrated that metformin and erlotinib together potentiate the inhibition of AKT and downstream S6 ribosomal protein which might be one of the mechanisms contributing to the observed synergy of the drugs.

Discussion: A significant subset of TNBC expresses EGFR, has PTEN loss and mutated p53. This recurrent set of lesions possibly leads to a unique and aberrant signaling and metabolic signature that confers TNBC an advantage for survival. We demonstrated that erlotinib and metformin act synergistically to remove this survival advantage in basal breast cancer cell lines while having minimal effect on normal epithelial breast cells. This drug combination potently down-regulates both the MAPK and PI3K pathways which are often aberrantly activated in basal-like breast tumors. Our results provide a rationale for the continued assessment of combining EGFR inhibitors with metformin in the treatment of TNBC.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD03-05.

Patterns of gene expression and copy-number alterations in von-hippel lindau disease-associated and sporadic clear cell carcinoma of the kidney

Recent insights into the role of the von-Hippel Lindau (VHL) tumor suppressor gene in hereditary and sporadic clear-cell renal cell carcinoma (ccRCC) have led to new treatments for patients with metastatic ccRCC, although virtually all patients eventually succumb to the disease. We performed an integrated, genome-wide analysis of copy-number changes and gene expression profiles in 90 tumors, including both sporadic and VHL disease-associated tumors, in hopes of identifying new therapeutic targets in ccRCC. We identified 14 regions of nonrandom copy-number change, including 7 regions of amplification (1q, 2q, 5q, 7q, 8q, 12p, and 20q) and 7 regions of deletion (1p, 3p, 4q, 6q, 8p, 9p, and 14q). An analysis aimed at identifying the relevant genes revealed VHL as one of three genes in the 3p deletion peak, CDKN2A and CDKN2B as the only genes in the 9p deletion peak, and MYC as the only gene in the 8q amplification peak. An integrated analysis to identify genes in amplification peaks that are consistently overexpressed among amplified samples confirmed MYC as a potential target of 8q amplification and identified candidate oncogenes in the other regions. A comparison of genomic profiles revealed that VHL disease-associated tumors are similar to a subgroup of sporadic tumors and thus more homogeneous overall. Sporadic tumors without evidence of biallelic VHL inactivation fell into two groups: one group with genomic profiles highly dissimilar to the majority of ccRCC and a second group with genomic profiles that are much more similar to tumors with biallelic inactivation of VHL.

Recurrent gross mutations of the PTEN tumor suppressor gene in breast cancers with deficient DSB repair

Basal-like breast cancer (BBC) is a subtype of breast cancer with poor prognosis. Inherited mutations of BRCA1, a cancer susceptibility gene involved in double-strand DNA break (DSB) repair, lead to breast cancers that are nearly always of the BBC subtype; however, the precise molecular lesions and oncogenic consequences of BRCA1 dysfunction are poorly understood. Here we show that heterozygous inactivation of the tumor suppressor gene Pten leads to the formation of basal-like mammary tumors in mice, and that loss of PTEN expression is significantly associated with the BBC subtype in human sporadic and BRCA1-associated hereditary breast cancers. In addition, we identify frequent gross PTEN mutations, involving intragenic chromosome breaks, inversions, deletions and micro copy number aberrations, specifically in BRCA1-deficient tumors. These data provide an example of a specific and recurrent oncogenic consequence of BRCA1-dependent dysfunction in DNA repair and provide insight into the pathogenesis of BBC with therapeutic implications. These findings also argue that obtaining an accurate census of genes mutated in cancer will require a systematic examination for gross gene rearrangements, particularly in tumors with deficient DSB repair.

p63 regulates commitment to the prostate cell lineage

Molecular mechanisms underlying prostate and urothelial development remain unclear. This situation presents major limitations in identifying the cell type(s) and molecular events involved in the development of prostate and bladder cancer. It has been shown that mice lacking the basal cell marker p63 present several epithelial defects, including epidermis and prostate buds agenesis and urothelial abnormalities. Here, we use the p63-/- mouse as a tool to define cell lineages in the prostate epithelium and urothelium. By complementing p63-/- blastocysts with p63+/+ beta-galactosidase (beta-gal)-positive ES cells, we show that secretory cells of the prostate originate from p63-positive basal progenitor cells. Importantly, our urogenital sinus transplantation studies demonstrate that p63 prevents intestinal differentiation of the urogenital sinus endoderm and is therefore required to maintain commitment to the prostate cell lineage. Finally, in contrast with the prostate findings, analysis of the urothelium from rescued p63-/- chimeras shows that umbrella (superficial) cells can develop and be maintained independently from p63-positive basal and intermediate cells.

[Intestinal absorption of D-xylose in children infected with the human immunodeficiency virus]

AIM

To evaluate the intestinal absorption in HIV-infected children children 14 months to 14 years and to investigate its relationship to diarrhea, nutritional status, immune dysfunction, classical enteric parasites and Cryptosporidium.

METHODS

Intestinal absorption was investigated by measuring serum D-xylose. Fecal samples were investigated for classical pathogens and Cryptosporidium. The sample size was calculated considering a 30% prevalence of altered D-xylose absorption in HIV-infected children with a 5% accuracy. Statistical procedures used were: descriptive measurements, multiple correspondence analysis and logistic regression.

RESULTS

D-xylose absorption was altered in only 8 out of 104 (7.7%) and Cryptosporidium was positive in 33 out of 104 (31.73%) HIV-infected children. The multiple correspondence analysis suggested an association between an altered D-xylose test and Cryptosporidium. D-xylose malabsorption was not associated with diarrhea, nutritional status, immune disfunction and classic enteric parasites.

CONCLUSIONS

Intestinal malabsorption evaluated through the D-xylose test was an uncommon finding in HIV-infected children. Intestinal dysfunction when present seems to be related to Cryptosporidium, but not to diarrhea, nutritional status, immune disfunction and classic enteric parasites.

Mature teratoma of the middle ear

OBJECTIVE

The authors report a case of mature teratoma of the middle ear in a 3-year-old girl with a 1-year history of otitis media.

METHODS AND RESULTS

Radiologic investigation revealed a partially cystic lesion of the petrous portion of the right temporal bone. It produced opacification of the middle ear as well as destruction of septal air cells. The patient underwent a subtotal petrosectomy. Histologically, the tumor was composed of an intimate admixture of mature tissues representing all three germ layers, including brain, myelinated nerve trunks, skeletal muscle, bone, immature cartilage, seromucinous glands, and respiratory epithelium. Of note within the brain tissue was choroid plexus within an ependyma-lined rudimentary ventricle. Immunohistochemical studies were also performed. Twenty months after surgery, the patient was well, with complete recovery from symptoms.

CONCLUSION

Teratomas of the middle ear are rare neoplasms. Only a few examples have been reported. As a rule, they are cured by resection and do not require adjuvant therapy.

Noval mutation (Y184C) in exon 4 of the beta-sarcoglycan gene identified in a Portuguese patient. Mutations in brief no. 177. Online

We report a novel beta-sarcoglycan gene mutation identified in a 21-year-old Portuguese male with a progressive myopathy of intermediate severity, who had been misdiagnosed as Becker Muscular Dystrophy (BMD) based on clinical observations and muscle immunocytochemical anaylsis with dystrophin antibodies only. Since no detectable deletions or duplications were found in the dystrophin gene, we screened for mutations in the sarcoglycan genes by PCR-SSCP. The patient's sample showed a band of increased mobility in exon 4 of the beta-sarcoglycan gene which, upon sequencing, was found to represent a homozygous A-->G transversion at nucleotide 551, resulting in a tyrosine to cysteine substitution at position 184 (Y184C). Carrier status was ascertained in both parents and a sister. These aberrant conformers were not detected in 85 unrelated control individuals screened by PCR-SSCP analysis. All seven beta-sarcoglycan mutations reported to date are associated with a severe phenotype and occur in exons 3 and 4, which correspond to the immediate extracellular domain of the protein. This region contains five conserved cysteine residues. In our patient, the presence of an extra cysteine residue could interefere with intra- and/or inter-molecular disulphide bond formation. The intermediate phenotype could perhaps result from the assembly of both normal and abnormal complexes, depending on the formation of the disulphide bonds.

L-2-Hydroxyglutaric aciduria: clinical, biochemical and magnetic resonance imaging in six Portuguese pediatric patients

We present clinical, biochemical and cranial magnetic resonance imaging data of six pediatric patients with L-2-hydroxyglutaric aciduria. All the children have the same ethic origin and lived in the northern area of Portugal. Our findings reinforce the described phenotype of this rare metabolic disease with mental deficiency, severe cerebellar dysfunction, mild extrapyramidal and pyramidal symptoms, progressive macrocephaly and seizures. Magnetic resonance imaging revealed subcortical leukoencephalopathy, cerebellar atrophy and signal changes in the putamina and dentate nuclei. These were similar to those of the previous reports in all patients. The urinary excretion of L-2-hydroxyglutaric acid was variably increased in all patients. The other persistent biochemical abnormality was hyperlysinemia. We have found a strong correlation between the severity of the clinical manifestations and the extension of the lesions in the neuroimaging studies. There was no correlation between the clinical findings and the amount of urinary excretion of L-2-hydroxyglutaric acid. We report the second case in the literature of a cerebral thalamic tumor in L-2-hydroxyglutaric aciduria; neuropathological examination of the surgical biopsy demonstrated a diffuse fibrillary astrocytoma.

[Frontal lobe-type dementia associated with motor neuron disease]

A case of presenile dementia with dominant frontal disfunction, progressive aphasia and Motor Neuron Disease with prominent bulbar signs is reported. Considering the clinical examination, the measurements of the regional cerebral flow (SPECT) and the histological appearances, we suggest the diagnosis of Dementia of Frontal Lobe Type and Motor Neuron Disease. We reviewed other disorders labelled Primary Frontal or Fronto-temporal Dementias and we discuss this new dementia and the difficulty in its classification.

First report of glaucoma as a feature of the 3C syndrome

We report the seventh case of the 3C syndrome or Cranio-Cerebello-Cardiac dysplasia. The presence of congenital glaucoma in our patient suggests that this is a previously undescribed feature of this syndrome, which is presumed to be autosomal recessive.

Multifocal astrocytoma presenting as action myoclonus

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Giant axonal disease: report of three cases and review of the literature

We describe three cases of Giant Axonal Neuropathy (GAN) with clinical signs of central nervous system involvement and an abnormal CT in one case. Two of these cases are sibs, pointing to an autosomal recessive inheritance as two other families previously reported. The review of the literature shows that most cases have central nervous system and cranial nerves involvement suggesting a generalized disorder in keeping an inborn error of organization of intermediate filaments. According to this, we think that Giant Axonal Disease (GAD) is a better designation to this condition.

Computed tomographic findings of brain and skull in myotonic dystrophy

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Vascular permeability in transplantable murine gliomas: morphological correlation with tracer studies

Invasive astrocytomas were produced in mice by intracerebral injection of a cell line obtained from a spontaneous murine astrocytoma. These tumours grew in the cerebral hemispheres and, in many cases, extended through the needle hole in the skull to give rise to large extracranial tumours. On injection of the tracers, Evans' blue or horseradish peroxidase (HRP), into the femoral vein, differences were noted in the vascular permeability of the intracerebral and extracranial tumours; the latter alone being stained. Ultrastructurally, small amounts of HRP were localized on the luminal membranes of the vascular endothelium in intracerebral tumours, while in extracranial neoplasms, the tracer was present in the widened extracellular space and in the cytoplasm of macrophages and neoplastic cells. Accordingly, endothelial fenestrations, open junctions and irregular vessels with hypertrophic endothelia were seen exclusively in extracranial neoplasms. These anomalies in the vasculature of intracerebral and extracranial components of VMDk P 497 tumours may have important implications in chemotherapeutic studies using this glioma model.

Four cases of late onset metachromatic leucodystrophy in a family: clinical, biochemical and neuropathological studies

Four cases of familial metachromatic leucodystrophy are described: the age of onset ranged from 15 to 21 years. Mental deterioration was the earliest clinical sign to be noted and all progressed to severe dementia. The arylsulphatase activity in peripheral leucocytes of the patients was very low, 5 to 15 nmol/h/mg protein, moderately reduced in the heterozygote, 40 nmol/h/mg protein, compared with control values of 60-160 nmol/h/mg protein. Sural nerve biopsies in two cases showed perivascular macrophages filled with metachromatic material and electron microscopy showed typical inclusions in Schwann cell cytoplasm. Necropsy in one of the cases revealed severe demyelination mainly in the cerebral hemispheres with metachromatic material in macrophages and neurons.

The peripheral neuropathy in Machado-Joseph disease

Peripheral nerve biopsies were taken from 11 patients with Machado-Joseph disease (MJD), a heredo-degenerative disease within the group of autosomal dominant ataxias. On the basis of the clinical symptoms, 2 patients were found to suffer from type I, 4 from type II and 5 from type III. All cases shared the same pathological features, which consisted of a reduction in density of myelinated and unmyelinated fibres and an increase in endoneurial collagen. It was also observed that some Schwann cells were not related to axons, whilst others showed numerous budding processes. The intensity of the changes varied considerably: it was mild in type I and II and severe in type III. Peripheral nerve changes in MJD are compared with those previously described in other forms of heredo-ataxias. It is concluded that involvement of peripheral nerves is a significant feature in this group of diseases and that peripheral nerve biopsy could be useful in the identification of the subtypes of MJD.