High level of apoptosis and low AKT activation in mass screening as opposed to standard neuroblastoma.

AIMS: Neuroblastoma is a paediatric solid tumour with a poor outcome except in children <1 year old. Based on catecholamine urinary excretion, mass screening (MS) programmes have been organized but failed to decrease the mortality of this tumour. To test the hypotheses of a spontaneous maturation/differentiation or regression, the levels of poly (ADP-ribose) polymerase (PARP)-1, an early apoptosis marker, of PhosphoAKT, a major apoptosis inhibitor, and of maturation/differentiation were compared in standard and in MS neuroblastomas. METHODS AND RESULTS: We performed a case-control study of 55 primary tumours and 21 metastases of MS neuroblastomas. Matched controls were standard unscreened neuroblastomas and were paired according to age, stage, and MYCN amplification. The tumours were included in tissue microarrays. Immunohistochemical staining was performed using antibodies against, AKT, phosphoAKT, TRKB and PARP-1. The expression of PARP-1 and that of phosphoAKT were significantly higher in standard than in MS neuroblastomas independently of age and stage of the tumour. PhosphoAKT and PARP-1 expression was significantly correlated in both tumours. CONCLUSIONS: These data suggest that the better prognosis of patients with MS neuroblastomas compared with classical neuroblastomas was secondary to spontaneous tumour regression mediated by higher levels of apoptosis associated with low activation of AKT.

High-throughput assays probing protein-RNA interactions of eukaryotic translation initiation factors.

Protein-RNA interactions are involved in all facets of RNA biology. The identification of small molecules that selectively block such bimolecular interactions could provide insight into previously unexplored steps of gene regulation. Such is the case for regulation of eukaryotic protein synthesis where interactions between messenger RNA (mRNA) and several eukaryotic initiation factors govern the recruitment of 40S ribosomes (and associated factors) to mRNA templates during the initiation phase. We have designed simple fluorescence polarization-based high-throughput screening assays that query the binding of several translation factors to RNA and found that the mixed inhibitor p-chloromercuribenzoate interferes with poly(A) binding protein-RNA interaction.

Role of immunohistochemical overexpression of matrix metalloproteinases MMP-2 and MMP-11 in the prognosis of death by ovarian cancer.

Matrix metalloproteinases (MMPs) are enzymes thought to be involved in tumor invasion. We hypothesized that MMP-2 and MMP-11 overexpression was associated with the aggressiveness of ovarian carcinoma. This study was performed on samples from 100 patients with stage III ovarian carcinomas treated surgically between 1990 and 2000. Immunohistochemical staining was performed on ovarian tumors and peritoneal implants using monoclonal antibodies. Overexpression was defined as more than 10% of cells expressing the marker. Multivariate analyses showed that only MMP-2 overexpression by cancer cells in peritoneal implants was associated with a significant risk of death by disease (hazard ratio, 2.65; 95% confidence interval, 1.41-4.97; P =.003). MMP-11 overexpression was not predictive of survival. These results suggest that MMP-2 overexpression by cancer cells in peritoneal implants and not in the primary ovarian cancer is predictive of ovarian cancer prognosis and more likely reflects the presence of particularly aggressive clones of cancer cells.

An upstream open reading frame impedes translation of the huntingtin gene.

Expansion of a CAG tract within the huntingtin gene, leading to the production of a protein with an expanded polyglutamine tract, is responsible for Huntington's disease. We show here that the 5' untranslated region (UTR) of the huntingtin gene plays an important role in controlling the synthesis of huntingtin. In particular, the 5' UTR contains an upstream open reading frame (uORF) encoding a 21 amino acid peptide. We demonstrate that the presence of this uORF negatively influences expression from the huntingtin mRNA. Our results suggest a role for the uORF in limiting ribosomal access to downstream initiation sites. Mechanisms involving the post-transcriptional regulation of huntingtin are not well understood, and this may be an important way of regulating huntingtin protein levels.

Inhibitory properties of nucleic acid-binding ligands on protein synthesis.

The use of small molecule inhibitors in the study of cellular processes is a powerful approach to understanding gene function. During the course of a high throughput screen for novel inhibitors of eukaryotic translation, we identified a number of nucleic acid binding ligands that showed activity in our assay. When tested on a panel of mRNA transcripts displaying different modes of translation initiation, these ligands showed a range of biological activities--with some inhibiting both cap-dependent and internal initiation and others preferentially blocking internal initiation. We used this information to identify a novel threading intercalator that inhibits Hepatitis C virus internal initiation.

Structure-activity relationships of quassinoids for eukaryotic protein synthesis.

The effect of 63 quassinoids on eukaryotic protein synthesis has been investigated. Seventeen of the tested compounds showed potent in vitro activity, with IC50s below 2 microM for inhibition in Krebs ascites translation extracts. Sixteen of these quassinoids were also potent inhibitors of in vivo protein synthesis when exposed to Hela cells for 1 h. Our results led to the following structure-activity relationships for quassinoids regarding translation inhibition. Activity is influenced by (i) the nature of the C-15 side chain, (ii) the nature of A ring modifications, (iii) the presence or absence of a sugar moiety, and (iv) the presence of an epoxymethano bridge.

[Amyloidosis of the seminal vesicles: a local condition with no systemic impact]. / L'amyloïdose des vésicules séminales, une condition localisée sans répercussion systémique.

AIM: Localised seminal vesicle amyloidosis is relatively infrequent and we present 9 additional cases. MATERIAL: and methods: Those 9 cases were retrospectively retrieved from 803 radical prostatectomies performed between 1995 and 2000 for prostatic adenocarcinoma. In each case, the type of amyloidosis was characterised by immunohistochemistry. Information regarding a possible concurrent disease or prior hormone therapy has been obtained. RESULTS: The prevalence of amyloidosis of seminal vesicles is lower in our study (1.1%) than in unselected autopsy cases. The prevalence of amyloidosis in patients exposed to prior hormone therapy (LHRH agonist and anti-androgen) was 2% while it reached only 0.9% in those who received no hormone therapy (p>0.3). No patient had systemic amyloidosis and all cases were of non A-A type. Lactoferrin, a glycoprotein produced by normal seminal vesicles, was detected in more than a half of them (5/9). CONCLUSION: No association was found between the occurrence of seminal vesicle amyloidosis and occurrence of a prostatic adenocarcinoma, corcomitant systemic disease or exposure to prior hormone therapy. Seminal vesicle amyloidosis is a localised condition without systemic involvement and amyloid deposition is composed mostly of lactoferrin.

In vitro and in vivo study of human amniotic fluid-derived stem cell differentiation into myogenic lineage.

Recent findings have shown that amniotic fluid (AF) could be a putative new source of multipotent stem cells (SC). We investigated whether these human SC could efficiently differentiate into myogenic lineage in vitro and integrate in vivo skeletal muscle in severe combined immunodeficiency (SCID) mice. C/kit immunomagnetic-sorted AF (AF c/kit+) SC were characterized by immunocytochemistry and Southern blotting for myogenic markers (desmin, MyoD). In vitro, AF c/kit+ SC phenotypic conversion into myogenic cells was assayed by myogenic-specific induction media. AF c/kit+ SC without ex vivo manipulation were transplanted into the tibialis anterior (TA) of (SCID) mice. Acquisition of a myogenic-like phenotype (desmin, MyoD) in AF c/kit+ SC was observed after culture in myogenic-specific induction media. In vivo, transplanted AF c/kit+ SC showed an engraftment in the skeletal muscle of SCID mice, but with unexpected tubular glandular tissue-like differentiation. Importantly, no immuno-rejection, inflammatory response or tumorigenicity of these cells was found. Within these experimental conditions, AF c/kit+ SC were able to differentiate into myogenic cells in vitro, but not in vivo after their transplantation into the skeletal muscle of SCID mice. Because AF c/kit+ SC survived and differentiated into tubular gland-like cells after their transplantation in the TA, an ex vivo engagement in myogenic pathway prior their transplantation could favor their differentiation into myogenic cells in vivo.

Bilateral cystic dysplasia of the rete testis with renal adysplasia.

Cystic dyplasia of the rete testis (CDRT) is an uncommon, generally unilateral lesion characterized by anastomosing cystic spaces lined by a flattened simple cuboidal epithelium in the rete testis. In the literature this lesion often is associated with an ipsilateral urogenital lesion such as renal agenesia or multicystic dysplasia of the kidney, in order of frequency. The pathogenesis is explained by some authors by their common embryologic origin. We are reporting the finding of bilateral CDRT associated with ultrasound-diagnosed renal adysplasia in a 20-week gestational age fetus with oligohydramnios. Although CDRT has been referred to as being associated with multicystic renal dysplasia or renal agenesis, the present case appears to be unique in combining all the malformations together.

An association of pleuropulmonary blastoma and cystic nephroma: possible genetic association.

The association of pleuropulmonary blastoma and cystic nephroma is an uncommon entity, with only 4 cases of such an association in the same patient described in English literature. We report a 5th histologically documented case in a 32-month-old boy. The boy underwent a pulmonary biopsy that showed a pleuropulmonary blastoma and a nephrectomy that showed a cystic nephroma. The pleuropulmonary mass showed an important regression with postbiopsy chemotherapy, allowing subsequent tumorectomy. To date very little is known about this rare entity, and a genetic link between these 2 tumors is hypothesized.

Inhibition of translation by RNA-small molecule interactions.

Small molecule ligand-RNA interactions have the potential to influence gene expression at a variety of steps and in a number of ways. Here, we demonstrate that such interactions are sufficiently stable to inhibit translation of eukaryotic mRNAs in vitro and in vivo. Inhibition is only observed when the 5' UTR of the mRNA is targeted, and the response is proportional to the number of binding sites within this region. We find that small molecule ligand-RNA interactions can be sufficiently stable to prevent 80S ribosome assembly on an mRNA template. The ability to specifically ablate expression of a defined mRNA with a small molecule ligand demonstrates proof of principle for pharmacological targeting aimed at controlling translation of specific mRNAs.

Forced engagement of a RNA/protein complex by a chemical inducer of dimerization to modulate gene expression.

A general strategy is described for forcing the engagement of an RNA/protein complex by using small-molecule ligands. A bivalent molecule was created by linking a protein-binding ligand to an RNA-binding ligand. On presentation of the chemical inducer of dimerization to the RNA by the protein, cooperative binding ensued, resulting in higher-affinity complexes. When the chemical inducer of dimerization was used to target the protein to an mRNA template, the resulting RNA/protein complex was sufficiently stable to inhibit mRNA translation. This approach provides a logic to modulate gene expression by using small-molecule ligands to recruit protein surfaces to mRNAs.

Eukaryotic protein synthesis inhibitors identified by comparison of cytotoxicity profiles.

The National Cancer Institute (NCI) Human Tumor Cell Line Anti-Cancer Drug Screen has evaluated the cytotoxicity profiles of a large number of synthetic compounds, natural products, and plant extracts on 60 different cell lines. The data for each compound/extract can be assessed for similarity of cytotoxicity pattern, relative to a given test compound, using an algorithm called COMPARE. In applying a chemical biology approach to better understand the mechanism of eukaryotic protein synthesis, we used these resources to search for novel inhibitors of translation. The cytotoxicity profiles of 31 known protein synthesis inhibitors were used to identify compounds from the NCI database with similar activity profiles. Using this approach, two natural products, phyllanthoside and nagilactone C, were identified and characterized as novel protein synthesis inhibitors. Both compounds are specific for the eukaryotic translation apparatus, function in vivo and in vitro, and interfere with translation elongation. Our results demonstrate the feasibility of utilizing cytotoxicity profiles to identify new inhibitors of translation.

Inhibition of protein synthesis by aminoglycoside-arginine conjugates.

Inhibition of translation by small molecule ligands has proven to be a useful tool for understanding this complex cellular mechanism, as well as providing drugs of significant medical importance. Many small molecule ligands inhibit translation by binding to RNA or RNA/protein components of the ribosomal subunits and usurping their function. A class of peptidomimetics [aminoglycoside-arginine conjugates (AAC)] has recently been designed to inhibit HIV TAR/tat interaction and in experiments aimed at assessing the inhibitory effects of AACs on TAR-containing transcripts, we found that AACs are general inhibitors of translation. Experiments reported herein aim at characterizing these novel properties of AACs. We find that AACs are inhibitors of eukaryotic and prokaryotic translation and exert their effects by blocking peptide chain elongation. Structure/activity relationship studies suggest that inhibition of translation by AACs is directly related to the number of arginine groups present on the aminoglycoside backbone and to the nature of the core aminoglycoside. AACs are therefore attractive tools for understanding and probing ribosome function.