Conditional reprogramming culture conditions facilitate growth of lower-grade glioma models

BACKGROUND

The conditional reprogramming cell culture method was developed to facilitate growth of senescence-prone normal and neoplastic epithelial cells, and involves co-culture with irradiated fibroblasts and the addition of a small molecule Rho kinase (ROCK) inhibitor. The aim of this study was to determine whether this approach would facilitate the culture of compact low-grade gliomas.

METHODS

We attempted to culture 4 pilocytic astrocytomas, 2 gangliogliomas, 2 myxopapillary ependymomas, 2 anaplastic gliomas, 2 difficult-to-classify low-grade neuroepithelial tumors, a desmoplastic infantile ganglioglioma, and an anaplastic pleomorphic xanthoastrocytoma using a modified conditional reprogramming cell culture approach.

RESULTS

Conditional reprogramming resulted in robust increases in growth for a majority of these tumors, with fibroblast conditioned media and ROCK inhibition both required. Switching cultures to standard serum containing media, or serum-free neurosphere conditions, with or without ROCK inhibition, resulted in decreased proliferation and induction of senescence markers. Rho kinase inhibition and conditioned media both promoted Akt and Erk1/2 activation. Several cultures, including one derived from a NF1-associated pilocytic astrocytoma (JHH-NF1-PA1) and one from a BRAF p.V600E mutant anaplastic pleomorphic xanthoastrocytoma (JHH-PXA1), exhibited growth sufficient for preclinical testing in vitro. In addition, JHH-NF1-PA1 cells survived and migrated in larval zebrafish orthotopic xenografts, while JHH-PXA1 formed orthotopic xenografts in mice histopathologically similar to the tumor from which it was derived.

CONCLUSIONS

These studies highlight the potential for the conditional reprogramming cell culture method to promote the growth of glial and glioneuronal tumors in vitro, in some cases enabling the establishment of long-term culture and in vivo models.

TAMI-49. THE ALTERNATIVE SPLICING FACTOR MBNL1 INHIBITS GLIOBLASTOMA TUMOR INITIATION AND PROGRESSION BY REDUCING HYPOXIA-INDUCED STEMNESS

Muscleblind-like-proteins (MBNL) belong to a family of tissue-specific RNA metabolism-regulators that control pre-messenger RNA-splicing (AS). Inactivation of MBNL causes an adult-to-fetal AS transition, resulting in the development of myotonic dystrophy. We have previously shown that the aggressive brain cancer, glioblastoma (GBM), maintains stem-like features (GSC) through hypoxia-induced responses. Accordingly, we hypothesized that the hypoxia-induced responses in GBM might also include MBNL-based AS to promote tumor progression. When cultured in hypoxia, GSCs rapidly export MBNL1 out of the nucleus resulting in significant inhibition of MBNL1 activity. Notably, the hypoxia-regulated inhibition of MBNL1 also resulted in evidence of adult-to-fetal alternative splicing transitions. Forced expression of a constitutively active isoform of MBNL1 inhibited GSC self-renewal and tumor initiation in orthotopic transplantation models. Using a tetracycline-inducible system, induced expression of MBNL1 in established orthotopic tumors dramatically inhibited tumor progression resulting in a significant prolongation of survival. This study reveals that MBNL1 plays an essential role in GBM stemness and tumor progression, whereby hypoxic responses within the tumor inhibit MBNL1 activity, promoting stem-like phenotypes and tumor growth. Reversing these effects on MBNL1 may, therefore, yield potent tumor-suppressor activities, uncovering new therapeutic opportunities to counter this devastating disease.

The Ig superfamily protein PTGFRN coordinates survival signaling in glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most malignant primary brain tumor with a median survival of approximately 14 months. Despite aggressive treatment of surgical resection, chemotherapy and radiation therapy, only 3-5% of GBM patients survive more than 3 years. Contributing to this poor therapeutic response, it is believed that GBM contains both intrinsic and acquired mechanisms of resistance, including resistance to radiation therapy. In order to define novel mediators of radiation resistance, we conducted a functional knockdown screen, and identified the immunoglobulin superfamily protein, PTGFRN. In GBM, PTGFRN is found to be overexpressed and to correlate with poor survival. Reducing PTGFRN expression radiosensitizes GBM cells and potently decreases the rate of cell proliferation and tumor growth. Further, PTGFRN inhibition results in significant reduction of PI3K p110β and phosphorylated AKT, due to instability of p110β. Additionally, PTGFRN inhibition decreases nuclear p110β leading to decreased DNA damage sensing and DNA damage repair. Therefore overexpression of PTGFRN in glioblastoma promotes AKT-driven survival signaling and tumor growth, as well as increased DNA repair signaling. These findings suggest PTGFRN is a potential signaling hub for aggressiveness in GBM.

Abstract 3147: Comprehensive characterization of the role of T-type calcium channels in glioblastoma

Glioblastoma stem cells (GSCs) have been implicated in tumor resistance to radio- and chemotherapy. Proliferation of GSCs reportedly requires calcium influx through T-type calcium channels (Cav3.2). In this study we investigated the expression, function, mechanism of action and therapeutic targeting of Cav3.2 with the FDA approved and repurposed drug Mibefradil in glioblastoma (GBM), and GSCs. We found that Cav3.2 is highly expressed in the majority of human GBM specimens and all GCSs. TCGA data analysis demonstrated that approximately 11% of GBM tumors have upregulated Cav3.2 and that overexpression of Cav3.2 is associated with worse prognosis. Furthermore, we demonstrated that Mibefradil inhibits GSC growth and survival and sensitizes GSCs to Temozolomide (TMZ) chemotherapy. Mibefradil inhibited hypoxia inducible factor HIF1a and induced GSC differentiation. To investigate the mechanism of action of Mibefradil, were performed proteomic and transcriptomic screenings of Mibefradil-treated GSCs using reverse phase protein arrays and RNA-seq, followed by functional rescue experiments. Inhibition of Cav3.2 with Mibefradil significantly altered multiple cancer regulatory signaling pathways and molecules as well as the transcription of oncogenes and tumor suppressors. Among other, Mibefradil suppressed GSC growth through inhibition of pro-survival pathways such as AKT/mTOR, whilst simultaneously inducing apoptosis through upregulation of survivin, BAX and cleavage of caspase 9 and PARP. Notably also, RNA-deep sequencing of Mibefradil treated GSCs revealed an increase in expression of tumor suppressors such as TNFRSF14 and HSD17B14 along with a decrease in the expression of several oncogenes such as PDGFA, PDGFB and TGFB1. We also assessed the therapeutic effects of Mibefradil, on established GSC-derived xenografts. Oral administration of Mibefradil significantly inhibited tumor growth, prolonged animal survival and sensitized tumors to inhibition by TMZ and radiation. This study represents the first comprehensive characterization of Cav3.2 in GBM and GSC. The data establish Cav3.2 inhibition by the repurposed FDA-approved drug Mibefradil as a new strategy for GBM therapy.

Citation Format: Ying Zhang, Nichola Cruickshanks, Fang Yuan, Baomin Wang, Mary Pahuski, Julia Wulfkuhle, Isela Gallagher, Alexander F. Koeppel, Sarah Hatef, Christopher Papanicolas, Jeongwu Lee, Eli Bar, David Schiff, Stephen D. Turner, Emanuel Petricoin, Lloyd L. Gray, Roger Abouander. Comprehensive characterization of the role of T-type calcium channels in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3147. doi:10.1158/1538-7445.AM2017-3147

Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation

Gradient-directed cell migration (chemotaxis) and growth (chemotropism) are processes that are essential to the development and life cycles of all species. Cells use surface receptors to sense the shallow chemical gradients that elicit chemotaxis and chemotropism. Slight asymmetries in receptor activation are amplified by downstream signaling systems, which ultimately induce dynamic reorganization of the cytoskeleton. During the mating response of budding yeast, a model chemotropic system, the pheromone receptors on the plasma membrane polarize to the side of the cell closest to the stimulus. Although receptor polarization occurs before and independently of actin cable-dependent delivery of vesicles to the plasma membrane (directed secretion), it requires receptor internalization. Phosphorylation of pheromone receptors by yeast casein kinase 1 or 2 (Yck1/2) stimulates their internalization. We showed that the pheromone-responsive Gβγ dimer promotes the polarization of the pheromone receptor by interacting with Yck1/2 and locally inhibiting receptor phosphorylation. We also found that receptor phosphorylation is essential for chemotropism, independently of its role in inducing receptor internalization. A mathematical model supports the idea that the interaction between Gβγ and Yck1/2 results in differential phosphorylation and internalization of the pheromone receptor and accounts for its polarization before the initiation of directed secretion.

Mesh-covered embolic protection stent implantation in ST-segment-elevation myocardial infarction: final 1-year clinical and angiographic results from the MGUARD for acute ST elevation reperfusion trial

BACKGROUND

The MGuard, a bare metal stent covered with a polymer mesh, was designed to reduce distal embolization during percutaneous coronary intervention in ST-segment-elevation myocardial infarction. In the MGUARD for Acute ST Elevation Reperfusion trial, the primary end point of complete ST-segment resolution was significantly improved with the MGuard compared with control. We evaluated 1-year clinical and angiographic results.

METHODS AND RESULTS

Patients with ST-segment-elevation myocardial infarction ≤12 hours undergoing primary percutaneous coronary intervention of a single de novo native lesion were randomized to the MGuard versus any commercially available metallic stent (39.8% drug-eluting). Clinical follow-up was performed through 1 year, and angiography at 13 months was planned in 50 MGuard patients. There was no difference in major adverse cardiac events (1.8% versus 2.3%; P=0.75) at 30 days between the groups. Major adverse cardiac events at 1 year were higher with the MGuard, driven by greater ischemia-driven target lesion revascularization (8.6% versus 0.9%; P=0.0003). Conversely, mortality tended to be lower with the MGuard at 30 days (0% versus 1.9%; P=0.04) and at 1 year (1.0% versus 3.3%; P=0.09). Late lumen loss at 13 months in the MGuard was 0.99±0.80 mm, and binary restenosis was 31.6%.

CONCLUSIONS

In patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention, a trend toward reduced 1-year mortality was present in patients treated with the MGuard stent. Target lesion revascularization and major adverse cardiac events rates during follow-up were higher in the MGuard group than in the control stent group, and angiographic late loss of the MGuard was consistent with that expected from bare metal stents.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01368471.

Abstract 3954: SAT1 (Spermidine/spermine-N1-acetyltrasferase 1) promotes radiation resistance in glioblastoma multiforme

Glioblastoma multiforme (GBM), is the most common and severe form of brain cancer. The median survival time is approximately 14 months due to poor responses to surgery, radiation and chemotherapy. GBM cells have been shown to exhibit high resistance to radiation. In order to understand the mechanisms involved in radioresistance, we conducted a genetic screen using a shRNA library on GBM cell lines to identify genes whose inhibition would sensitize cells to radiation. The results were cross-referred with the Oncomine and Rembrandt databases to focus on genes that are highly expressed in GBM tumors, and are associated with poor patient outcomes. Spermidine/spermine-N1-acetyltransferase 1 (SAT1), an enzyme involved in polyamine catabolism, was identified as a gene that promotes resistance to ionizing radiation (IR), is overexpressed in brain tumors and its high expression correlates with poor outcomes. The objective of this study is to explore the role of SAT1 in radioresistance with the purpose of targeting SAT1 as a means to sensitize tumors. The knockdown of SAT1 using, shRNA and siRNA approaches, in multiple cell lines and neurosphere lines results in sensitization of GBM cells to radiation in colony formation assays. This was seen specifically in G2/M and S phases, leading to the hypothesis that SAT1 plays a role in homologous recombination (HR). By measuring HR in the DR-GFP reporter system, we confirmed that SAT1 promotes HR, since depletion of SAT1 results in decrease in HR. To test whether SAT1 depletion sensitizes cells to S-phase poisons, SAT1 knockdown GBM cells were then exposed to camptothecin, and were found to be sensitized. To explore the mechanisms of interaction of SAT1 with the DNA damage pathway, chromatin immunoprecipitation (ChIP) was performed under the theory that polyamine-DNA interactions may be altered during DNA repair. The results show that polyamines are decreased in the chromatin of the HR site following induction of double-strand breaks. Interestingly, western blot analyses show that SAT1 knockdown decreases the levels of acetylated histone 3 (H3) proteins, suggesting a new role of SAT1 in chromatin remodeling. Overall the results suggest that SAT1 is involved in radioresistance in GBM through regulation of HR and alterations in chromatin remodeling at sites of damage. Our findings suggest that the biological significance of SAT1 expression in GBM lies in its contribution to cell radioresistance and SAT1 may potentially be a therapeutic target to sensitize GBM to cancer therapies.

Citation Format: Adina Brett-Morris, Scott M. Welford, Eli Bar, Raffaella Spina, Bradley Wright, Junran Zhang, Jun Lu, Yuji Seo. SAT1 (Spermidine/spermine-N1-acetyltrasferase 1) promotes radiation resistance in glioblastoma multiforme. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3954. doi:10.1158/1538-7445.AM2014-3954

MicroRNA profiling in pediatric pilocytic astrocytoma reveals biologically relevant targets, including PBX3, NFIB, and METAP2

Pilocytic astrocytoma (PA) is a World Health Organization grade I glioma that occurs most commonly in children and young adults. Specific genetic alterations have been described in PA, but the pathogenesis remains poorly understood. We studied microRNA (miRNA) alterations in a large cohort of patients with PA. A total of 43 PA, including 35 sporadic grade I PA, 4 neurofibromatosis-1 (NF1)-associated PA, and 4 PA with pilomyxoid features, as well as 5 nonneoplastic brain controls were examined. BRAF fusion status was assessed in most cases. RNA was examined using the Agilent Human miRNA Microarray V3 platform. Expression of miRNA subsets was validated using quantitative real-time PCR (qRT-PCR) with Taqman probes. Validation of predicted protein targets was performed on tissue microarrays with the use of immunohistochemistry. We identified a subset of miRNAs that were differentially expressed in pediatric PAs versus normal brain tissue: 13 miRNAs were underexpressed, and 20 miRNAs were overexpressed in tumors. Differences were validated by qRT-PCR in a subset, with mean fold change in tumor versus brain of -17 (miR-124), -15 (miR-129), and 19.8 (miR-21). Searching for predicted protein targets in Targetscan, we identified a number of known and putative oncogenes that were predicted targets of miRNA sets relatively underexpressed in PA. Predicted targets with increased expression at the mRNA and/or protein level in PA included PBX3, METAP2, and NFIB. A unique miRNA profile exists in PA, compared with brain tissue. These miRNAs and their targets may play a role in the pathogenesis of PA.

BRAF activation induces transformation and then senescence in human neural stem cells: a pilocytic astrocytoma model

PURPOSE

BRAF is frequently activated by gene fusion or point mutation in pilocytic astrocytoma, the most common pediatric brain tumor. We investigated the functional effect of constitutive BRAF activation in normal human neural stem and progenitor cells to determine its role in tumor induction in the brain.

EXPERIMENTAL DESIGN

The constitutively active BRAF(V600E) allele was introduced into human neurospheres, and its effects on MAPK (mitogen-activated protein kinase) signaling, proliferation, soft agarose colony formation, stem cell phenotype, and induction of cellular senescence were assayed. Immunohistochemistry was used to examine p16(INK4a) levels in pilocytic astrocytoma.

RESULTS

BRAF(V600E) expression initially strongly promoted colony formation but did not lead to significantly increased proliferation. BRAF(V600E)-expressing cells subsequently stopped proliferating and induced markers of oncogene-induced senescence including acidic β-galactosidase, PAI-1, and p16(INK4a) whereas controls did not. Onset of senescence was associated with decreased expression of neural stem cell markers including SOX2. Primary pilocytic astrocytoma cultures also showed induction of acidic β-galactosidase activity. Immunohistochemical examination of 66 pilocytic astrocytomas revealed p16(INK4a) immunoreactivity in the majority of cases, but patients with tumors negative for p16(INK4a) had significantly shorter overall survival.

CONCLUSIONS

BRAF activation in human neural stem and progenitor cells initially promotes clonogenic growth in soft agarose, suggesting partial cellular transformation, but oncogene-induced senescence subsequently limits proliferation. Induction of senescence by BRAF may help explain the low-grade pathobiology of pilocytic astrocytoma, whereas worse clinical outcomes associated with tumors lacking p16(INK4a) expression could reflect failure to induce senescence or an escape from oncogene-induced senescence.

Abstract 3303: BRAF activation induces cellular transformation and senescence and down-regulates SOX2 in human neural stem cells: a model of pilocytic astrocytoma

In pilocytic astrocytomas, the primary molecular alteration is BRAF activation occurring via gene duplication/fusion or V600E point mutation. To investigate the mechanisms by which BRAF activation leads to transformation, BRAF V600E was introduced into cortical and cerebellar human fetal neural stem and progenitor cells. Overexpression of BRAF V600E did not lead to increases in cellular proliferation compared to controls, but did promote colony forming ability in soft agar. However, after initially growing well, BRAF V600E expressing cells subsequently showed decreased proliferation as compared to control cells, though they remained viable visually. Because constitutive BRAF activation in melanocytes usually leads to cellular senescence, with only rare lesions progressing to melanoma, we examined if senescent markers were induced in our system. Overexpression of BRAF V600E led to an increase in markers of oncogene-induced senescence, such as acidic beta-galactosidase and p16. FISH analysis revealed no differences in telomere length in BRAF over-expressing cells compared to GFP-transduced control cells, indicating that this phenotype was not due to telomere shortening. The pattern of initial transformation followed by senescence is similar to the frequently indolent course of pilocytic astrocytoma, suggesting that overexpressing constitutively active BRAF in human neural stem and progenitor cells phenocopies the behavior of this tumor. To further investigate the mechanism of oncogene-induced senescence, we examined SOX2 expression. This human somatic cell reprogramming factor is an important neurodevelopmental gene and is known to prevent the induction of cellular senescence. However, the functional role of SOX2 in gliomas is poorly understood. We found that although SOX2 was expressed in control GFP transduced neurospheres, high-level expression of BRAFV600E led to downregulation of SOX2 in association with senescence. Our data support the concept that BRAF oncogene-induced senescence plays a role in the pathobiology of pilocytic astrocytoma, and suggest that modulation of SOX2 may play an important role in this process.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3303. doi:10.1158/1538-7445.AM2011-3303

Abstract 4440: Using nanocurcumin to treat medulloblastoma and glioblastoma

We attempted to treat medulloblastoma and glioblastoma, malignant tumors of the central nervous system, with curcumin, a polyphenolic compound derived from the Indian spice turmeric. Curcumin was delivered in a nanoparticle-encapsulated formulation (nanocurcumin) to increase its solubility and bioavailability. Nanocurcumin caused a dose-dependent decrease in cell growth as measured by MTT in multiple brain cancer cell lines, including the embryonal tumor derived cultures DAOY, D283, and PFSK, and the glioblastoma neurosphere line HSR-GBM1. Notably, doses used in these studies did not cause a comparable inhibition in the growth of NIH 3T3 cells or non-neoplastic human fetal cortical neurospheres. The reductions in viable cell mass observed were associated with a combination of G2/M arrest and apoptotic induction. The proportion of G2/M cells increased between 25% and 106% in the various lines, while the percentage of apoptotic cells increased at least two-fold. Nanocurcumin was also found to reduce the CD133+ stem-like cancer cell population in medulloblastoma and glioblastoma cells. In the primary glioblastoma culture JHH-GBM14, the CD133+ population decreased from 7.7% to 0.6%. In addition, 10uM nanocurcumin suppressed clonogenicity of our brain tumor cell lines by more than 97%. Curcumin has been shown to target multiple pathways in different tumor types. We found that Stat3 activity was reduced by nanocurcumin in the DAOY medulloblastoma cell line, via reductions in phospho-Tyr705 and phospho-Ser727. Nanocurcumin also reduced the expression of Hes 5, one of the target genes in the Notch pathway. However, we did not find significant changes in protein expression of Bcl2, MEK, ERK and Akt following nanocurcumin treatment. In conclusion, our results suggest that nanocurcumin can inhibit malignant brain tumor growth, at least in part due to reduction in Stat activity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4440.

Long-term, stable differentiation of human embryonic stem cell-derived neural precursors grafted into the adult mammalian neostriatum

Stem cell grafts have been advocated as experimental treatments for neurological diseases by virtue of their ability to offer trophic support for injured neurons and, theoretically, to replace dead neurons. Human embryonic stem cells (HESCs) are a rich source of neural precursors (NPs) for grafting, but have been questioned for their tendency to form tumors. Here we studied the ability of HESC-derived NP grafts optimized for cell number and differentiation stage prior to transplantation, to survive and stably differentiate and integrate in the basal forebrain (neostriatum) of young adult nude rats over long periods of time (6 months). NPs were derived from adherent monolayer cultures of HESCs exposed to noggin. After transplantation, NPs showed a drastic reduction in mitotic activity and an avid differentiation into neurons that projected via major white matter tracts to a variety of forebrain targets. A third of NP-derived neurons expressed the basal forebrain-neostriatal marker dopamine-regulated and cyclic AMP-regulated phosphoprotein. Graft-derived neurons formed mature synapses with host postsynaptic structures, including dendrite shafts and spines. NPs inoculated in white matter tracts showed a tendency toward glial (primarily astrocytic) differentiation, whereas NPs inoculated in the ventricular epithelium persisted as nestin(+) precursors. Our findings demonstrate the long-term ability of noggin-derived human NPs to structurally integrate tumor-free into the mature mammalian forebrain, while maintaining some cell fate plasticity that is strongly influenced by particular central nervous system (CNS) niches.

Expression of chromosomally inserted bacillus thuringiensis israelensis toxin genes in bacillus sphaericus

Bacillus thuringiensis israelensis delta-endotoxin genes were inserted into transposon Tn917 in plasmid pTV51Ts and cloned into the chromosome of Bacillus sphaericus 2362. Many of the transformants reacted with antibody to the 135-, 128-, 65-, and 28-kDa B.t.israelensis toxin proteins and were approximately 10 times more toxic to A. aegypti larvae than the untransformed host. Some of the transformants differed physiologically and morphologically from the wild-type B. sphaericus. The toxicity of the transformed phenotype was maintained through many transfers in the absence of selective pressure. Copyright 1998 Academic Press.

Assessment of DNA damage induced in vitro by etoposide and two fungicides (carbendazim and chlorothalonil) in human lymphocytes with the comet assay

The effects of two fungicides (carbendazim and chlorothalonil) on the induction of DNA damage in human peripheral blood lymphocytes (human PBL) have been investigated using the single cell gel electrophoresis assay (SCGE assay or comet assay) immediately after a 1-h treatment and after a 24-h post-treatment incubation. The assessment of etoposide (an effective antitumour agent) effects on human PBL in terms of cell viability and dose-DNA damage relationships was made and etoposide selected as a positive control. The results indicate that etoposide induces significant (p < 0.01) dose-dependent DNA damages for concentrations at which the loss of cell viability is low. After a 24-h recuperation period, all observed DNA damages has disappeared. With SCGE assay performed after a 1-h treatment, similar positive results were observed with chlorothalonil alone or in association with carbendazim, without any loss of cell viability. However, a dramatic loss of cell viability was measured after 24 h and was associated with a large proportion of highly damaged cells. In contrast, carbendazim was not cytotoxic on human PBL and did not induced DNA damage using the SCGE assay either immediately after treatment or after a 24-h post-treatment incubation. These results point to the necessity of an adequate evaluation of immediate and long-term cytotoxicity of compounds that are to be assessed by the SCGE assay.

Biological markers and ovarian carcinomas: galactosyltransferase, CA 125, isoenzymes of amylase and alkaline phosphatase

We present a comparative study of several biological markers (galactosyltransferase, CA 125, isoenzymes of amylase and alkaline phosphatase) with a view to ovarian carcinoma follow-up. Serum samples were obtained from a population of 75 patients under clinical observation. After a minimum 18-months period, we assessed the prognostic value of the markers. No marker permits the detection of discrete, evolving carcinomas. CA 125 is the marker that gives the best results, particularly in terms of sensitivity. Galactosyltransferase has a lower sensitivity except in the case of endometrioid carcinomas. Simultaneous analysis with CA 125 and galactosyltransferase results in no decisive improvement, other than greater precision in unfavourable prognoses. Isoenzymes of amylase and alkaline phosphatase are of no interest in the follow-up of such carcinomas.

Cloning and expression of Bacillus thuringiensis israelensis delta-endotoxin DNA in B. sphaericus

Bacillus thuringiensis israelensis delta-endotoxin genes were cloned into Bacillus sphaericus 2362, producing stable transformants reacting with antibody to the 28- and 65-kDa B. thuringiensis israelensis crystal proteins and approximately 10 times more toxic to Aedes mosquito larvae than the original host strain. The LC50 after 48 hr of exposure of Aedes larvae to the most active transformed clone was 0.19 microgram/ml, compared with an LC50 of 1.9 microgram/ml for B. sphaericus 2362 and less than 0.1 microgram/ml for B. thuringiensis israelensis. The cloning vector, plasmid pPL603E, was also effective in transforming B. subtilis 1E20 with B. thuringiensis israelensis DNA, producing highly toxic clones with less stable gene expression than the clones of B. sphaericus.

A simple serum galactosyltransferase assay method suitable for routine use

UDP-Galactose: N-acetylglucosaminyl glycoprotein beta 1-4 galactosyltransferase (GT) catalyzes the transfer of galactose to N-acetylglucosamine from UDP-[3H]Gal. The uncharged reaction product (tritiated N-acetyllactosamine) is separated from the unreacted UDP-[3H]Gal by ion-exchange chromatography. The major advantage of this method is its rapidity compared to other isotopic techniques.

Alteration in isoenzyme patterns of serum galactosyltransferase activity in ovarian cancer patients: preliminary results

Isoelectric focusing on agarose gel was used to separate the isoenzymes of serum galactosyltransferase (uridine diphosphogalactose: N-acetylglucosaminyl galactosyltransferase, EC 2.4.1.22) from 8 healthy women, and 11 ovarian cancer patients of whom 4 were in clinical remission. In all cases, we found 7 major peaks with isoelectric points ranging from 4.0-5.4. The most acidic peaks were preferentially elevated in the tumor-bearing patients, particularly the peak with pI 4.44.

Serum galactosyltransferase activity with three acceptors in ovarian cancer patients

Several laboratories have demonstrated the usefulness of serum galactosyltransferase as a biological marker for ovarian neoplasms. However, contradictory results have been published recently, which might be partially explained by differences in methodology. We thus decided to measure serum galactosyltransferase activity in patients with ovarian cancer and benign gynecological diseases using three different assay systems. A very good correlation was obtained between the results of these assays. Furthermore, we confirm that serum GT is frequently elevated in cancer patients, and is of potential value for their follow-up.