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Biomedical subjects

C D James

Publications and source records attributed to C D James.

At least 19 recordsLinked to original sources
PubMed2005

ECop (EGFR-coamplified and overexpressed protein), a novel protein, regulates NF-kappaB transcriptional activity and associated apoptotic response in an IkappaBalpha-dependent manner.

In the present study, we describe the function of a novel protein, ECop (EGFR-Coamplified and overexpressed protein), in the regulation of NF-kappaB activity. Ectopic expression of ECop increases NF-kappaB transcriptional activity by promoting nuclear translocation and DNA binding of NF-kappaB, and ECop-induced NF-kappaB activation confers cellular resistance to apoptotic challenge. In ECop knockdown cells, NF-kappaB transcriptional activity is suppressed due to delayed IkappaBalpha degradation, which results in a delayed nuclear translocation as well as decreased DNA binding of NF-kappaB. Suppression of NF-kappaB activation by ECop knockdown increases cellular susceptibility to apoptosis. These results suggest that ECop is a key regulator of NF-kappaB signaling, and that high-level, amplification-mediated ECop expression, such as that occurring in tumors with amplified EGFR, could contribute to resistance to apoptosis.

Apoptosis↗
PubMed2004

Alosetron repeat dose pharmacokinetics, effects on enzyme activities, and influence of demographic factors.

AIM: To assess the pharmacokinetics of alosetron, its effect on in vivo enzyme activities, and influence of demographic factors during repeated dosing. METHODS: Thirty healthy men and women received 1 mg oral alosetron twice-daily for 29.5 days and a single oral dose of a metabolic probe cocktail before and on the last day of alosetron dosing. Serum alosetron concentrations were measured on days 1, 8, 15, 22 and 29. Probe-substrate and metabolite concentrations were measured after each cocktail dose. RESULTS: Alosetron accumulation in serum was negligible. Exposure to alosetron did not alter probe-metabolite/substrate ratios associated with CYP2C19, 2E1, 2C9, or 3A4 activity, but modestly decreased those associated with CYP1A2 and N-acetyltransferase activity. Systemic exposure to alosetron was higher in women, positively correlated with age and body mass index, and negatively correlated with CYP1A2 activity. Incidence of constipation was higher in women, but not associated with alosetron concentration. CONCLUSIONS: Single dose data can reliably predict the pharmacokinetics of alosetron after repeated doses. Alosetron exhibits limited potential for inhibition of cytochrome P450-mediated metabolism. Interindividual differences in alosetron pharmacokinetics associated with demographic factors may be related to strong dependence on metabolism by CYP1A2.

Administration, Oral↗
PubMed2003

Molecular analysis of astrocytomas presenting after age 10 in individuals with NF1.

BACKGROUND: Fifteen to 20% of children with neurofibromatosis type 1 (NF1) develop low-grade astrocytomas. Although brain tumors are less common in teenagers and adults with NF1, recent studies have suggested that patients with NF1 are at a significantly increased risk of developing astrocytomas. OBJECTIVE: S: To investigate the genetic basis for astrocytoma development in patients with NF1 beyond the first decade of life. METHODS: The authors performed molecular genetic analyses of 10 NF1-associated astrocytomas representing all World Health Organization (WHO) malignancy grades using fluorescence in situ hybridization, loss of heterozygosity, immunohistochemistry, and direct sequencing. RESULTS: Later-onset NF1-associated astrocytomas, unlike histologically identical sporadic astrocytomas, exhibit NF1 inactivation, supporting a direct association with NF1 rather than a chance occurrence. Furthermore, some of these astrocytomas have homozygous NF1 deletion. In addition, genetic changes observed in high-grade sporadic astrocytomas, including TP53 mutation and CDKN2A/p16 deletion, are also seen in NF1-associated high-grade astrocytomas. CONCLUSIONS: Neurofibromatosis type 1-associated astrocytomas occurring in patients older than 10 years exhibit genetic changes observed in sporadic high-grade astrocytomas. Patients with neurofibromatosis type 1 and germline NF1 deletions may be at risk for developing late-onset astrocytomas.

Adolescent↗
PubMed2001

PTEN mutation, EGFR amplification, and outcome in patients with anaplastic astrocytoma and glioblastoma multiforme.

BACKGROUND: Survival of patients with anaplastic astrocytoma is highly variable. Prognostic markers would thus be useful to identify clinical subsets of such patients. Because specific genetic alterations have been associated with glioblastoma, we investigated whether similar genetic alterations could be detected in patients with anaplastic astrocytoma and used to identify those with particularly aggressive disease. METHODS: Tissue specimens were collected from 174 patients enrolled in Mayo Clinic Cancer Center and North Central Cancer Treatment Group clinical trials for newly diagnosed gliomas, including 63 with anaplastic astrocytoma and 111 with glioblastoma multiforme. Alterations of the EGFR, PTEN, and p53 genes and of chromosomes 7 and 10 were examined by fluorescence in situ hybridization, semiquantitative polymerase chain reaction, and DNA sequencing. All statistical tests were two-sided. RESULTS: Mutation of PTEN, amplification of EGFR, and loss of the q arm of chromosome 10 were statistically significantly less common in anaplastic astrocytoma than in glioblastoma multiforme (P =.033, P =.001, and P<.001, respectively), and mutation of p53 was statistically significantly more common (P<.001). Univariate survival analyses of patients with anaplastic astrocytoma identified PTEN (P =.002) and p53 (P =.012) mutations as statistically significantly associated with reduced and prolonged survival, respectively. Multivariate Cox analysis of patients with anaplastic astrocytoma showed that PTEN mutation remained a powerful prognostic factor after adjusting for patient age, on-study performance score, and extent of tumor resection (hazard ratio = 4.34; 95% confidence interval = 1.82 to 10.34). Multivariate classification and regression-tree analysis of all 174 patients identified EGFR amplification as an independent predictor of prolonged survival in patients with glioblastoma multiforme who were older than 60 years of age. CONCLUSION: PTEN mutation and EGFR amplification are important prognostic factors in patients with anaplastic astrocytoma and in older patients with glioblastoma multiforme, respectively.

Adolescent↗
PubMed2001

Genetic analysis of early- versus late-stage ovarian tumors.

In the United States, ovarian cancer is the fourth most common cause of cancer-related deaths among women. The most important prognostic factor for this cancer is tumor stage, or extent of disease at diagnosis. Although women with low-stage tumors have a relatively good prognosis, most women diagnosed with late-stage disease eventually succumb to their cancer. In an attempt to understand early events in ovarian carcinogenesis, and to explore steps in its progression, we have applied multiple molecular genetic techniques to the analysis of 21 early-stage (stage I/II) and 17 advanced-stage (stage III/IV) ovarian tumors. These techniques included expression profiling with cDNA microarrays containing approximately 18,000 expressed sequences, and comparative genomic hybridization to address the chromosomal locations of copy number gains as well as losses. Results from the analysis indicate that early-stage ovarian cancers exhibit profound alterations in gene expression, many of which are similar to those identified in late-stage tumors. However, differences observed at the genomic level suggest differences between the early- and late-stage tumors and provide support for a progression model for ovarian cancer development.

Disease Progression↗
PubMed2001

Use of viral fusogenic membrane glycoproteins as novel therapeutic transgenes in gliomas.

Malignant gliomas are the most common primary brain tumors in adults and, with few exceptions, have a dismal prognosis despite the therapeutic use of surgery, radiation therapy, and chemotherapy. Because CNS gliomas rarely metastasize, they represent an attractive target for gene therapy through local gene delivery. Here we report on the use of two different fusogenic membrane glycoproteins (FMGs), the measles virus proteins F and H (MV-F and MV-H) and a mutated form of the retroviral envelope protein of the gibbon ape leukemia virus (GALV.fus), as a novel class of therapeutic transgenes in gliomas. Transfection of U87 and U118 cells with MV-F and MV-H cDNA or GALV.fus cDNA led in 48 hr to massive syncytial formation followed by cell death. FMG-mediated cytotoxicity in the U87 and U118 cell lines was superior to the cytotoxicity caused by transfection with HSV-tk cDNA followed by ganciclovir (GCV) treatment at all time points. At high-density cell seeding, addition of tumor cells transfected with MV-F and H killed at least 1 log more cells than by HSV-tk + GCV treatment, indicating higher bystander effect. Similar results were obtained with GALV.fus. The mechanism of syncytial death in cultured glioma cell lines was predominantly apoptotic. Transfection of U87 cells with F + H or GALV.fus expression constructs completely suppressed their tumorigenicity. Treatment of established U87 xenografts in nude mice with a combination of F and H adenoviruses at 1:1 ratio led to complete tumor regression, significantly higher antitumor effect, and prolongation of survival as compared with control animals treated with a GFP adenovirus. In summary, the viral fusogenic membrane glycoproteins (GALV and the MV-F + MV-H combination) are potent therapeutic transgenes with potential utility in the gene therapy of gliomas.

Animals↗
PubMed2001

Cancer-related gene expression profiles in NF1-associated pilocytic astrocytomas.

BACKGROUND: Individuals affected with neurofibromatosis 1 (NF1) develop juvenile pilocytic astrocytomas (JPA) at an increased frequency, suggesting that the NF1 gene product, neurofibromin, functions as a negative growth regulator for astrocytes. Previously, the authors demonstrated that NF1-associated astrocytomas exhibit deletions and loss of NF1 gene expression on the DNA and protein levels. However, little is known about additional genetic events in clinically and radiographically progressive NF1-associated pilocytic astrocytomas. OBJECTIVE/METHODS: To understand the potential role of cooperating genetic events in the development of these low-grade tumors, the authors used immunohistochemistry and selected confirmatory Western blots to examine nine symptomatic NF1-associated pilocytic astrocytomas for gene products whose expression patterns are altered in fibrillary astrocytomas. RESULTS: The authors demonstrate that p53, p16, retinoblastoma (RB), epidermal growth factor receptor (EGFR), cyclin-dependent kinase 4 (CDK4), platelet-derived growth factor A (PDGF-A) and PDGF receptor alpha (PDGF-Ralpha) protein expression profiles are not altered in NF1-associated pilocytic astrocytomas. Similar to their sporadic counterparts, NF1-associated JPA also strongly expressed PEN5, a marker of post-O2A stage oligodendroglial precursor cells. CONCLUSIONS: These results suggest that NF1-associated pilocytic astrocytomas lack the genetic changes typically associated with the more clinically aggressive fibrillary astrocytomas and lay the foundation for future studies to identify NF1 JPA-specific alterations.

Adolescent↗
PubMed2001

The HER tyrosine kinase inhibitor CI1033 enhances cytotoxicity of 7-ethyl-10-hydroxycamptothecin and topotecan by inhibiting breast cancer resistance protein-mediated drug efflux.

Because the activities of HER family members are elevated and/or aberrant in a variety of human neoplasms, these cell surface receptors are receiving increasing attention as potential therapeutic targets. In the present study, we examined the effect of combining the HER family tyrosine kinase inhibitor CI1033 (PD 183805) with the topoisomerase (topo) I poison 7-ethyl-10-hydroxycamptothecin (SN-38), the active metabolite of irinotecan, in a number of different cell lines. Colony-forming assays revealed that the antiproliferative effects of simultaneous treatment with CI1033 and SN-38 were synergistic in T98G glioblastoma cells and HCT8 colorectal carcinoma cells, whereas sequential treatments were additive at best. In additional studies examining the mechanistic basis for these findings in T98G cells, immunoblotting revealed that the inhibitory effects of CI1033 on epidermal growth factor receptor autophosphorylation were unaffected by SN-38. Likewise, CI1033 had no effect on topo I polypeptide levels, localization, or activity. Nonetheless, CI1033 markedly enhanced the number of covalent topo I-DNA complexes stabilized by SN-38 or the related agent topotecan (TPT). Analysis of intracellular SN-38 levels by high-performance liquid chromatography and intracellular TPT levels by flow microfluorometry revealed that CI1033 increased the steady-state accumulation of SN-38 and TPT by 9.4 +/- 1.9- and 1.8 +/- 0.2-fold, respectively. Further evaluation revealed that the initial rate of TPT uptake was unaffected by CI1033, whereas the rate of efflux was markedly diminished. Additional studies demonstrated that T98G and HCT8 cells express the breast cancer resistance protein (BCRP), a recently cloned ATP binding cassette transporter. Moreover, CI1033 enhanced the uptake and cytotoxicity of SN-38 and TPT in cells transfected with BCRP but not empty vector. Conversely, CI1033 accumulation was diminished in cells expressing BCRP, suggesting that CI1033 is a substrate for this efflux pump. These results indicate that CI1033 can modulate the accumulation and subsequent cytotoxicity of two widely used topo I poisons in cells that have no history of previous exposure to these agents.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2001

Comparative genomic sequence analysis and isolation of human and mouse alternative EGFR transcripts encoding truncated receptor isoforms.

This study presents the annotated genomic sequence and exon-intron organization of the human and mouse epidermal growth factor receptor (EGFR) genes located on chromosomes 7p11.2 and 11, respectively. We report that the EGFR gene spans nearly 200 kb and that the full-length 170-kDa EGFR is encoded by 28 exons. In addition, we have identified two human and two mouse alternative EGFR transcripts of 2.4-3.0 kb using both computational and experimental methods. The human 3.0-kb and mouse 2.8-kb EGFR mRNAs are predominantly expressed in placenta and liver, respectively, and both transcripts encode 110-kDa truncated receptor isoforms containing only the extracellular ligand-binding domain. We also have demonstrated that the aberrant 2.8-kb EGFR transcript produced by the human A431 carcinoma cell line is generated by splicing to a recombinant 3'-terminal exon located in EGFR intron 16, which apparently was formed as a result of a chromosomal translocation. Finally, we have shown that the human, mouse, rat, and chicken 1.8- to 3.0-kb alternative EGFR transcripts are generated by distinct splicing mechanisms and that each of these mRNAs contains unique 3' sequences that are not evolutionarily conserved. The presence of truncated receptor isoforms in diverse species suggests that these proteins may have important functional roles in regulating EGFR activity.

Alternative Splicing↗
PubMed2001

Glioblastoma-related gene mutations and over-expression of functional epidermal growth factor receptors in SKMG-3 glioma cells.

Amplification of the epidermal growth factor receptor (EGFR) gene is found in about 40% of glioblastomas (GBMs) but is rarely detected in GBM cell lines. We confirmed that the exceptional SKMG-3 GBM cell line retained amplified EGFR genes in vitro, and found that these sequences were concentrated on extra-chromosomal DNA particles similar to double-minute chromosomes. The cells contained two other gene mutations that are associated with high-grade astrocytic tumors: extra-chromosomal amplification of the cyclin-dependent kinase-4 (CDK4) gene and a homozygous mutation within the PTEN tumor suppressor gene. Immunoblots revealed very high levels of EGFR, moderately increased expression of CDK4, and no detectable PTEN protein. The overexpressed SKMG-3 EGFRs responded to exogenous ligand and resembled normal rather than mutant receptors. A heterozygous mutation of the p53 gene (p53R282W) correlated with failure of radiation to induce the expression of cyclin-dependent kinase inhibitor p21waf1 or an early G1 cell cycle arrest. Although each of these gene mutations occurs in GBMs, SKMG-3 cells had an unusual genotype in that a p53 gene mutation co-existed with amplified EGFR genes. Nonetheless, the SKMG-3 cell line can be exploited as a model to study how oncogenic EGFR signals in GBM cells interact with over-expressed CDK4 and loss of PTEN to confer the malignant phenotype.

Blotting, Southern↗
PubMed2001

Analysis of p53 mutation and expression in pleomorphic xanthoastrocytoma.

Pleomorphic xanthoastrocytoma (PXA) is a rare, superficially situated tumor that most frequently occurs in the temporal lobe of young adults and is often associated with seizures. It generally has a relatively favorable prognosis. Prior studies have shown that TP53 mutations may occur in up to 25% of PXAs, suggesting that PXA may have an etiology similar to diffuse astrocytoma rather than pilocytic astrocytoma. In the present study, we performed immunostaining for p53 protein and examined the mutation status of exons 5-8 of the p53 gene in 55 PXAs, 8 of which had undergone one or multiple recurrences. Of 55 primary PXAs, 35 (64%) showed staining in <1% of tumor cells, 15 (27%) in 1-10%, 4 (7%) in 11-50%, and only 1 (2%) in >50%. No significant increase in p53 protein expression was noted in recurrences, even when associated with increased histological anaplasia. We found a TP53 heterozygous mutation in exon 7 in 1 of 47 primary tumors that yielded useable DNA, and in its recurrence 3 years later. This tumor, a grade II PXA, did not show signs of anaplastic transformation at recurrence. Eleven additional recurrences from 7 patients, 5 of which showed signs of histological anaplasia, did not show TP53 mutations in exons 5-8. Based on our data, the p53 mutation appears to be an uncommon (2%) genetic event in PXA formation and does not appear to be involved in tumor progression. Consequently, our findings suggest that the genetic events that underlie PXA formation differ from those involved in diffuse astrocytoma.

Astrocytoma↗
PubMed2001

Chromosomal abnormalities subdivide ependymal tumors into clinically relevant groups.

Ependymoma occurs most frequently within the central nervous system of children and young adults. We determined relative chromosomal copy-number aberrations in 44 ependymomas using comparative genomic hybridization. The study included 24 intracranial and 20 spinal cord tumors from pediatric and adult patients. Frequent chromosomal aberrations in intracranial tumors were gain of 1q and losses on 6q, 9, and 13. Gain of 1q and loss on 9 were preferentially associated with histological grade 3 tumors. On the other hand, gain on chromosome 7 was recognized almost exclusively in spinal cord tumors, and was associated with various other chromosomal aberrations including frequent loss of 22q. We conclude that cytogenetic analysis of ependymomas may help to classify these tumors and provide leads concerning their initiation and progression. The relationship of these aberrations to patient outcome needs to be addressed.

Adolescent↗
PubMed2001

Small cell architecture--a histological equivalent of EGFR amplification in glioblastoma multiforme?

Although there is much written about the molecular definitions of "primary" glioblastomas (GBM), there is little known about the histological features of this predominant subtype. We hypothesized that the "small cell architecture" would represent a histological feature of most primary GBMs. This was tested by comparing the presence of the small cell phenotype with the presence or absence of amplification of the epidermal growth factor receptor (EGFR), a common event in primary GBMs. After a pilot study that found a correlation between this small cell phenotype and EGFR amplification, we selected 9 pure small cell GBMs (SCGBM) and 12 non-SCGBMs to be studied for EGFR amplification by fluorescence in situ hybridization (FISH). In this set of 21 cases, 8 of 9 SCGBMs and 5 of 12 non-SCGBMs were amplified for EGFR. We then correlated the EGFR status of 79 GBMs unselected for their histological features from a set that had been previously characterized in regard to EGFR amplification. Fourteen of 21 (67%) exclusively small cell neoplasms, 8 of 25 (32%) GBMs with both small cell and non-small cell areas, and 3 of 33 (9%) non-small cell GBMs were amplified for EGFR (p = 0.0004 with an exact test). We conclude that EGFR amplification is associated with a small cell phenotype in GBMs and that SCGBMs are an important component of "primary" GBMs.

Brain Neoplasms↗
PubMed2001

PS6K amplification characterizes a small subset of anaplastic meningiomas.

PS6K, a putative oncogene mapped to chromosome 17q23, encodes a serine/threonine kinase, which phosphorylates ribosomal subunit 6 and is part of the insulin receptor signal transduction pathway involved in the regulation of messenger RNA translation, protein synthesis, cell cycle progression, and cell size. Comparative genomic hybridization studies have detected 17q23 amplifications in a subset of meningiomas, particularly those with aggressive histologic features. PS6K amplifications have been reported in breast cancer, another hormonally driven neoplasm. We assessed PS6K dosage in 94 archival paraffin-embedded meningiomas using dual-color fluorescence in situ hybridization. We found high-level PS6K amplifications in 3 of 22 anaplastic grade III meningiomas. Amplification was confirmed by differential polymerase chain reaction in 1 of these cases. In contrast, no amplifications were identified in 37 benign (grade I) and 35 atypical (grade II) meningiomas. To our knowledge, this represents the first report of gene amplification in primary human meningiomas. Given its exclusive association with anaplastic meningiomas, PS6K amplification likely occurs during the malignant progression of a small subset of anaplastic tumors. Further studies are needed to map the 17q23 amplicon to determine whether additional genes in this region are amplified in high-grade meningiomas.

DNA Primers↗
PubMed2000

17q23 amplifications in breast cancer involve the PAT1, RAD51C, PS6K, and SIGma1B genes.

Amplification of the 17q23 region occurs frequently in breast tumors. To characterize the structure of 17q23 amplicons and to identify oncogene targets associated with this alteration, we performed a copy number analysis of 87 17q23 localized expressed sequence tags in seven breast cancer cell lines. Three major regions of amplification were detected in the MCF7 and BT474 cell lines. Amplification of at least one of four known genes (PAT1, PS6K, RAD51C, and SIGMA1B) was detected in the cell lines and in 28% of 94 breast tumors. In most cases, these four genes were overexpressed when amplified, but there was a particularly good association between amplification of the SIGMA1B gene and elevated expression in tumors, which suggested a possible role for this gene in tumor progression. Our data show that this region contains at least four independent targets of amplification, which suggests that there is considerable variability in the structure of the 17q23 amplicon.

Breast Neoplasms↗
PubMed2000

Diversity and frequency of epidermal growth factor receptor mutations in human glioblastomas.

Several types of epidermal growth factor receptor (EGFR) gene mutations have been reported in glioblastomas, and in nearly all cases the alterations have been reported in tumors with EGFR amplification. The objectives of this study were to determine the frequency and diversity of EGFR mutations in glioblastomas and to determine whether gene mutation is inevitably associated with increased EGFR gene dosage. To accomplish these aims, we sequenced cDNA products representing the entire EGFR coding region in 44 glioblastomas, half of which had EGFR amplification. Coding sequence alterations were identified in 17 of the tumors, and each of these cases had amplified EGFR. No mutations were identified in the 22 tumors without EGFR amplification. An additional 26 glioblastomas with EGFR amplification were then examined to establish more reliable frequencies for each type of mutation identified in the tumors for which the entire gene was sequenced. Transcripts associated with the most common mutation lacked coding sequence for amino acids 6-273 (67%). This mutation has been described extensively in the literature. Transcripts encoding receptors that would truncate at amino acid 958 and transcripts encoding receptors that would lack amino acids 521-603 were the next most common types of alteration. Each of these were observed in 15% of the tumors with EGFR amplification. Other mutations were observed at lower frequencies, but among these were three cases with missense mutations. Sixteen of the 48 tumors with EGFR amplification showed multiple types of EGFR mutations (33%), and in one case it was determined that multiple alterations had occurred in the same transcript. In total, these data are consistent with EGFR mutation being exclusively and frequently associated with EGFR amplification. Furthermore, the determination of multiple EGFR mutations within individual tumors suggests that glioblastomas with EGFR amplification have the capacity to produce a variety of functionally distinct EGFRs.

Brain Neoplasms↗
PubMed2000

Incidence and subtype specificity of API2-MALT1 fusion translocations in extranodal, nodal, and splenic marginal zone lymphomas.

The t(11;18)(q21;q21) is thought to represent an important primary event in the development of marginal zone lymphomas, although an accurate estimation of the frequency and distribution of this genetic alteration among nodal, splenic, and extranodal marginal zone lymphoma types has yet to be determined. Recently, molecular genetic studies have shown that this translocation results in the fusion of the API2 gene on chromosome 11 and a novel gene termed MALT1 on chromosome 18. To investigate the incidence of API2-MALT1 fusion transcripts among marginal zone lymphomas and to determine possible marginal zone lymphoma subtype associations, we used reverse transcriptase-polymerase chain reaction to analyze RNAs extracted from frozen tissue samples of 99 marginal zone lymphomas. Fifty-seven involved diverse extranodal sites including 14 stomach, 11 lung, 7 orbit, 7 parotid, 5 thyroid, 5 lacrimal gland, 3 small intestine, 2 large intestine, 1 kidney, 1 paraspinal region and 1 skin. Twenty-one primary splenic and twenty-one primary nodal marginal zone lymphomas were also studied. API2-MALT1 fusion transcripts were detected in 12 of 57 extranodal marginal zone lymphomas (21%), but in none of the nodal or splenic cases. The cDNA sequences of the fusion transcripts were determined, revealing variation in the coding sequence fusion point for both API2 and MALT1. The findings suggest that t(11;18)(q21;q21) is restricted to extranodal marginal zone lymphomas and that these tumors have distinct genetic etiologies in comparison with their splenic and nodal counterparts.

Adult↗