Allele loss of tumour suppressor genes on chromosome 17 in human testicular germ cell tumours

The molecular genetics of testicular germ cell tumours (TGCT) are still largely unknown. We investigated 20 TGCT tumours for allelic losses (LOH) of tumour supressor genes BRCA1, TP53 and of THRA1 on chromosome 17. We observed an overall loss of 50% for the whole chromosome. Detailed deletion mapping revealed no losses for the BRCA1 gene, 42% LOH for THRA1 and 11% allelic loss for the region telomeric to BRCA1. We observed 11% LOH for TP53. Our results suggest that allelic losses of BRCA1 and TP53 genes do not play a pivotal role in TGCT but that dysfunction of THRA1 or tumour suppressor gene(s) in this region may have an impact in the development of this cancer.

The future of primary paediatric care in Europe: reflections and Report of the EPA/UNEPSA Committee

BACKGROUND

Changes in the scope of the field of paediatrics and the variability in primary paediatric care (PPC) and practice throughout Europe motivated the European Paediatric Association and Union of National European Paediatric Societies and Associations (EPA/UNEPSA) to establish a working group to discuss definitions of paediatric coverage in terms of age limits, find common denominators in the provision of PPC and examine the challenges and goals of 21st century paediatrics relevant to the continent. These issues were presented at the 2008 Europaediatrics in Istanbul, where a consensus declaration was drawn up and accepted by the EPA/UNEPSA Executive Committee.

AIM

To present an outline of the essential elements of the 2008 EPA/UNEPSA Executive Committee consensus declaration.

CONCLUSION

The definition of basic characteristics and the establishment of requirements for optimal PPC and practice are important steps in overcoming the differences among European countries and pave the way for an acceptable formulation of standardized high-quality paediatric medical care in Europe.

The BOADICEA model of genetic susceptibility to breast and ovarian cancers: updates and extensions

Multiple genetic loci confer susceptibility to breast and ovarian cancers. We have previously developed a model (BOADICEA) under which susceptibility to breast cancer is explained by mutations in BRCA1 and BRCA2, as well as by the joint multiplicative effects of many genes (polygenic component). We have now updated BOADICEA using additional family data from two UK population-based studies of breast cancer and family data from BRCA1 and BRCA2 carriers identified by 22 population-based studies of breast or ovarian cancer. The combined data set includes 2785 families (301 BRCA1 positive and 236 BRCA2 positive). Incidences were smoothed using locally weighted regression techniques to avoid large variations between adjacent intervals. A birth cohort effect on the cancer risks was implemented, whereby each individual was assumed to develop cancer according to calendar period-specific incidences. The fitted model predicts that the average breast cancer risks in carriers increase in more recent birth cohorts. For example, the average cumulative breast cancer risk to age 70 years among BRCA1 carriers is 50% for women born in 1920-1929 and 58% among women born after 1950. The model was further extended to take into account the risks of male breast, prostate and pancreatic cancer, and to allow for the risk of multiple cancers. BOADICEA can be used to predict carrier probabilities and cancer risks to individuals with any family history, and has been implemented in a user-friendly Web-based program (http://www.srl.cam.ac.uk/genepi/boadicea/boadicea_home.html).

Breast and ovarian cancer risks to carriers of the BRCA1 5382insC and 185delAG and BRCA2 6174delT mutations: a combined analysis of 22 population based studies

A recent report estimated the breast cancer risks in carriers of the three Ashkenazi founder mutations to be higher than previously published estimates derived from population based studies. In an attempt to confirm this, the breast and ovarian cancer risks associated with the three Ashkenazi founder mutations were estimated using families included in a previous meta-analysis of populatrion based studies. The estimated breast cancer risks for each of the founder BRCA1 and BRCA2 mutations were similar to the corresponding estimates based on all BRCA1 or BRCA2 mutations in the meta-analysis. These estimates appear to be consistent with the observed prevalence of the mutations in the Ashkenazi Jewish population.

Cerebral actinomycosis before adolescence

In a 10-year-old boy presenting with focal seizures and 6 months later with acute right-sided hemiparesis, the diagnosis of a cerebral abscess due to Actinomyces israelii was established. The immunocompetent child suffered from a complex congenital heart disease with pulmonary arteriovenous shunts and pulmonary hypertension causing mild cyanosis. His parents had been reluctant to agree to neuroimaging investigations resulting in a delayed diagnosis. Despite the long interval between first symptoms and commencement of treatment including neurosurgical excision of the abscess followed by a 4-week course of ceftriaxone, a complete recovery of the hemiparesis was observed. This patient is the first case with cerebral actinomycosis before adolescence reported so far.

Somatic mutations of KIT in familial testicular germ cell tumours

Somatic mutations of the KIT gene have been reported in mast cell diseases and gastrointestinal stromal tumours. Recently, they have also been found in mediastinal and testicular germ cell tumours (TGCTs), particularly in cases with bilateral disease. We screened the KIT coding sequence (except exon 1) for germline mutations in 240 pedigrees with two or more cases of TGCT. No germline mutations were found. Exons 10, 11 and 17 of KIT were examined for somatic mutations in 123 TGCT from 93 multiple-case testicular cancer families. Five somatic mutations were identified; four were missense amino-acid substitutions in exon 17 and one was a 12 bp in-frame deletion in exon 11. Two of seven TGCT from cases with bilateral disease carried KIT mutations compared with three out of 116 unilateral cases (P=0.026). The results indicate that somatic KIT mutations are implicated in the development of a minority of familial as well as sporadic TGCT. They also lend support to the hypothesis that KIT mutations primarily take place during embryogenesis such that primordial germ cells with KIT mutations are distributed to both testes.

Emerging roles of BRCA1 alternative splicing

Germline mutations of the BRCA1 gene predispose individuals mainly to the development of breast and/or ovarian cancer. However, the exact function of the gene is still unclear, although the encoded proteins are involved in various cellular processes, including transcriptional regulation and DNA repair pathways. Several BRCA1 splice variants are found in different tissues, but in spite of intense investigations, their regulation and possible functions are poorly understood at the moment. This review summarises current knowledge on the roles of these splice variants and the mechanisms responsible for their formation. Because alternative splicing is now widely accepted as an important source of genetic diversity, elucidating the functions of the BRCA1 splice variants would help in the understanding of the exact role(s) of this tumour suppressor. This should help to resolve the current paradox that, despite its seemingly vital cellular functions, mutations of this gene are associated with tissue specific tumour formation predominantly in the breast and the ovary.

Average risks of breast and ovarian cancer associated with BRCA1 or BRCA2 mutations detected in case Series unselected for family history: a combined analysis of 22 studies

Germline mutations in BRCA1 and BRCA2 confer high risks of breast and ovarian cancer, but the average magnitude of these risks is uncertain and may depend on the context. Estimates based on multiple-case families may be enriched for mutations of higher risk and/or other familial risk factors, whereas risk estimates from studies based on cases unselected for family history have been imprecise. We pooled pedigree data from 22 studies involving 8,139 index case patients unselected for family history with female (86%) or male (2%) breast cancer or epithelial ovarian cancer (12%), 500 of whom had been found to carry a germline mutation in BRCA1 or BRCA2. Breast and ovarian cancer incidence rates for mutation carriers were estimated using a modified segregation analysis, based on the occurrence of these cancers in the relatives of mutation-carrying index case patients. The average cumulative risks in BRCA1-mutation carriers by age 70 years were 65% (95% confidence interval 44%-78%) for breast cancer and 39% (18%-54%) for ovarian cancer. The corresponding estimates for BRCA2 were 45% (31%-56%) and 11% (2.4%-19%). Relative risks of breast cancer declined significantly with age for BRCA1-mutation carriers (P trend.0012) but not for BRCA2-mutation carriers. Risks in carriers were higher when based on index breast cancer cases diagnosed at <35 years of age. We found some evidence for a reduction in risk in women from earlier birth cohorts and for variation in risk by mutation position for both genes. The pattern of cancer risks was similar to those found in multiple-case families, but their absolute magnitudes were lower, particularly for BRCA2. The variation in risk by age at diagnosis of index case is consistent with the effects of other genes modifying cancer risk in carriers.

Constitutive intracellular expression and activation-induced cell surface up-regulation of CD44v3 in human T lymphocytes

The cell adhesion molecule CD44 exists in multiple isoforms generated by alternative RNA splicing. Increased expression of CD44 isoforms containing exon v6 and v9 has been reported to be associated with the activated state of T lymphocytes. Using monoclonal antibodies against variant exon products we studied the expression of another variant exon, v3 on resting and in vitro activated human peripheral blood T cells. We found that CD44v3, in parallel with CD44v6, is up-regulated at the surface of normal T cells stimulated by anti-CD3 antibody or by the phorbol ester PMA, as well as on PMA-stimulated T cell leukemia lines CCRF-CEM and MOLT-4. Beside the cell surface, we demonstrated CD44v3 intracellularly in both resting and activated T cells by flow cytometry and immunomorphology. Reverse transcription-PCR and Western blot analyses confirmed the constitutive expression of CD44v3 in these cells. The increase in the cell surface expression of CD44v3 on stimulated T lymphocytes was inhibited by cycloheximide and brefeldin A, indicating the requirement of de novo protein synthesis and endoplasmic reticulum Golgi transport. Our studies establish CD44v3 as an additional activation marker for human T cells, with a yet unidentified function.

Expression profiles of BRCA1 splice variants in asynchronous and in G1/S synchronized tumor cell lines

Disrupting the function of the BRCA1 gene by mechanisms other than germline mutations is suspected to occur in cases of sporadic breast/ovarian cancers. Using ribonuclease protection assay and multiplex RT-PCR, we examined the change of the total BRCA1 mRNA pool and the expression profile of four predominant BRCA1 splice variants in asynchronous and in G1/S synchronized tumor cell populations compared to normal breast cells. Experiments were carried out on MCF-7 and MDA-MB-231 breast cancer, OVCAR-5 ovarian cancer, and K562 leukemia cell lines. The ratio of the full length, the delta(11q), the delta(9,10), and the delta(9,10,11q) BRCA1 isoforms showed different expression patterns in the examined breast and ovarian tumor cell lines as compared to the leukemia cell line. This observation raises the possibility that the dysregulation of alternative splicing of the BRCA1 gene could be involved in tumor formation in the breast and the ovary, even in the absence of germline mutations.

Sequence alterations can mask each other's presence during screening with SSCP or heteroduplex analysis: BRCA genes as examples

For mutation detection, various screening techniques are widely used because DNA sequencing, the gold-standard method, is still considered to be expensive and laborious for high-throughput screening. Single-strand conformation polymorphism (SSCP) analysis, heteroduplex analysis (HA) and their variant techniques are popular and frequently used for this purpose. It is widely accepted that when searching for unknown sequence variations, any revealed distinct pattern should always be sequenced. We give examples here of the BRCA1 and BRCA2 genes where the SSCP/HA techniques can produce ambiguous predictions if used to detect known genetic variants compared to positive controls. Using direct DNA sequencing, we provide evidence that in such cases, mutations or polymorphisms can mask each other's presence. This phenomenon can often influence the results of any DNA testing because genetic variations such as single-nucleotide polymorphisms occur frequently in the human genome. We suggest that even in the case of known electrophoretic patterns of well-characterized genetic alterations, every sequence alteration should be confirmed by direct DNA sequencing, especially if genetic testing is carried out for diagnostic purposes.

Strong founder effects in BRCA1 mutation carrier breast cancer patients from Latvia. Mutation in brief no. 258. Online

Germ-line mutations of the BRCA1 gene account for approximately half of the cases of hereditary breast/ovarian cancers. We have screened index patients from 15 breast cancer families and 8 sporadic breast cancer patients from Latvia for mutations in all coding exons of the BRCA1 gene, using combined Heteroduplex Analysis/SSCP followed by direct sequencing of the variants. BRCA1 germ-line mutations proved to be frequent in Latvian breast cancer patients, also in moderate-risk families and sporadic patients. Out of 23 cases a total of 8 patients (35%) exhibited three different mutations (5382insC, C61G, 4153delA). Interestingly, these three recurrent mutations accounted for all mutations in our sample set and no unique mutation was found. The 5382insC and C61G mutations accounted for 63% (5/8) and 25% (2/8) of all mutations, respectively. Allelotyping suggested a common founder in each recurrent mutation. Additional one-hundred hospital-based incident breast cancer patients were screened for the three mutations and 4 other 5382insC mutation carriers were identified (4%). Patients with C61G and 4153delA mutations were all Latvians, whilst the majority of 5382insC carriers (7/9=78%) were of Russian ethnicity, which is intriguing for the supposed Baltic origin of this mutation.

Prevalence of founder BRCA1 and BRCA2 mutations among breast and ovarian cancer patients in Hungary

We have investigated the impact of BRCA1 and BRCA2 mutations that were frequently identified among Hungarian high-risk breast-ovarian cancer families (Ramus et al., 1997b, AJHG), on the development of breast and ovarian cancer in the general Hungarian population. The prevalence of 3 BRCA1 mutations (185delAG, 300T-->G and 5382insC) and 2 BRCA2 mutations (6174delT and 9326insA) was evaluated in a hospital-based consecutive series of 500 female breast cancer patients and 90 ovarian cancer patients, not selected for age at diagnosis or family history of cancer, as well as in 350 controls. Among breast cancer patients, 3.6% (18/500) carried a founder mutation: 9 BRCA1 300T-->G, 7 BRCA1 5382insC, 1 BRCA1 185delAG and 1 BRCA2 9326insA. Among ovarian cancer patients, 11% (10/90) carried a founder mutation: 5 BRCA1 185delAG, 4 BRCA1 300T-->G and 1 BRCA1 5382insC. One control carried a mutation, BRCA1 5382insC. Inherited breast cancer was more frequent among women with younger age at diagnosis: 6.1% of women younger than age 50 but 2.4% of women diagnosed at age 50 or older carried one of the founder mutations. There was no association between mutation status and age at diagnosis of ovarian cancer. Three of 23 medullary breast cancers were inherited (p = 0.038). Carrier status was also associated with a non-significant trend toward advanced tumor stage at diagnosis. These mutations could be evaluated among all ovarian cancer patients and breast cancer patients younger than age 60 and of Hungarian ancestry.

Founder BRCA1 mutations and two novel germline BRCA2 mutations in breast and/or ovarian cancer families from North-Eastern Poland

Germline mutations in the BRCA1 and BRCA2 genes account for the majority of high-risk breast/ovarian cancer families, depending on the population studied. Previously, BRCA1 mutations were described in women from Western Poland. To further characterize the spectrum of BRCA1 mutations and the impact of BRCA2 mutations in Poland, we have analyzed 25 high-risk breast and/or ovarian cancer families from North-Eastern Poland for mutations in all coding exons of the BRCA1 and BRCA2 genes, using combined heteroduplex analysis/SSCP followed by direct DNA sequence analysis. Out of 25 probands a total of five (20%) carried three recurrent BRCA1 mutations (300T>G, 3819del5, 5382insC). The 300T>G mutation accounted for 60% (3/5) of BRCA1 mutations and allelotyping suggested a common founder of this mutation. No unique mutations were found. In addition, we identified three BRCA2 (12%) mutations, one recurrent 4075delGT, and two novel frameshift mutations, 7327ins/dupl19 and 9068delA. We conclude that 30% of high-risk families from North-Eastern Poland may be due to recurrent BRCA1 and unique BRCA2 mutations. Intriguingly, the BRCA1 mutation spectrum seems to be different within subregions of Poland.

Germline mutation analysis of BRCA1 and BRCA2 genes in Yugoslav breast/ovarian cancer families

The frequency of germline BRCA1 and BRCA2 mutations was tested in Yugoslav breast and breast/ovarian cancer families using combined heteroduplex/single-strand conformation polymorphism analysis for the entire coding region of both genes. Three different recurrent BRCA1 mutations (one 185delAG, one 3447del4 and two 5382insC) were identified in 4 of 12 families (33%), whereas no definite disease-causing alterations of BRCA2 was detected. Genotype analysis revealed a possible common founder effect for each 185delAG and 5382insC. The relatively high frequency of germline BRCA1 mutations determined in this panel of families confirms the important role of BRCA1 in disease predisposition in the Yugoslav population, while the lack of population specific founder and/or unique mutations show the need of further analysis of samples from this yet unexamined region of Europe.

Loss of heterozygosity at 11q23.1 and survival in breast cancer: results of a large European study. Breast Cancer Somatic Genetics Consortium

Among the chromosomal regions commonly undergoing deletions in breast tumors is 11q23.1. The genes that are targets for loss of heterozygosity (LOH) in this region is not yet established. One of the candidate genes located in this region is ATM, responsible for the rare autosomal recessive disorder ataxia-telangiectasia (A-T). Interestingly, A-T heterozygotes may have an increased risk of cancer, in particular breast cancer, although this is still controversial. A common assumption has been that the target for the LOH at 11q23.1 in breast carcinoma is the ATM gene, but the area studied has been too large, the density of markers too low, and the number of tumors studied has been too small to draw any firm conclusions. The present study is a multicenter study including 918 breast cancer patients with clinical information and survival data available for most of them. Primary breast tumors were investigated for LOH using a high density of microsatellite markers spanning approximately 6 Mb around the ATM gene. Survival analyses showed that there are most likely one or more candidate genes in a 3-4 Mb region between the markers D11S1819 and D11S927 including the ATM gene. Cancer-specific survival was significantly reduced in patients whose tumors exhibited LOH of markers D11S2179 (within the ATM gene), D11S1778, D11S1294, and D11S1818. The highest survival hazard ratios were 1.8(C11.2-2.8, P = 0.010) and 2.1 (C11.4-3.0, P = 0.0004) for markers D11S2179 and D11S1818, respectively. One or more of these markers are therefore most likely to be located close to or within genes associated with breast cancer survival.

European multicenter study on LOH of APOC3 at 11q23 in 766 breast cancer patients: relation to clinical variables. Breast Cancer Somatic Genetics Consortium

High frequencies of loss of heterozygosity (LOH) in chromosome 11q22-qter have been observed in various malignancies, including breast cancer. Previous studies on breast carcinomas by Winqvist et al (Cancer Res 55: 2660-2664) have indicated that a survival factor gene is located in band 11q23, and that the highly informative microsatellite polymorphism at the APOC3 locus would be a suitable tool to perform more extensive LOH studies. In this European multicentre study, we have examined the occurrence of APOC3 LOH and evaluated the effect of LOH of this chromosomal subregion on the clinical behaviour of the disease in a cohort of 766 breast cancer patients in more detail. LOH for APOC3 was found in 42% of the studied tumours, but it was not found to be significantly associated with any of the studied clinical variables, including cancer-specific survival time or survival time after recurrent/metastatic disease. According to the present findings, the putative survival factor gene on 11q23 is not located close enough to the APOC3 gene, but apparently at a more proximal location.

High frequency of germ-line BRCA2 mutations among Hungarian male breast cancer patients without family history

To determine the contribution of BRCA1 and BRCA2 mutations to the pathogenesis of male breast cancer in Hungary, the country with the highest male breast cancer mortality rates in continental Europe, a series of 18 male breast cancer patients and three patients with gynecomastia was analyzed for germ-line mutations in both BRCA1 and BRCA2. Although no germ-line BRCA1 mutation was observed, 6 of the 18 male breast cancer cases (33%) carried truncating mutations in the BRCA2 gene. Unexpectedly, none of them reported a family history for breast/ovarian cancer. Four of six truncating mutations were novel, and two mutations were recurrent. Four patients (22%) had a family history of breast/ovarian cancer in at least one first- or second-degree relative; however, no BRCA2 mutation was identified among them. No mutation was identified in either of the genes in the gynecomastias. These results provide evidence for a strong genetic component of male breast cancer in Hungary.

Haplotype and phenotype analysis of nine recurrent BRCA2 mutations in 111 families: results of an international study

Several BRCA2 mutations are found to occur in geographically diverse breast and ovarian cancer families. To investigate both mutation origin and mutation-specific phenotypes due to BRCA2, we constructed a haplotype of 10 polymorphic short tandem-repeat (STR) markers flanking the BRCA2 locus, in a set of 111 breast or breast/ovarian cancer families selected for having one of nine recurrent BRCA2 mutations. Six of the individual mutations are estimated to have arisen 400-2,000 years ago. In particular, the 6174delT mutation, found in approximately 1% of individuals of Ashkenazi Jewish ancestry, was estimated to have arisen 29 generations ago (1-LOD support interval 22-38). This is substantially more recent than the estimated age of the BRCA1 185delAG mutation (46 generations), derived from our analogous study of BRCA1 mutations. In general, there was no evidence of multiple origins of identical BRCA2 mutations. Our study data were consistent with the previous report of a higher incidence of ovarian cancer in families with mutations in a 3.3-kb region of exon 11 (the ovarian cancer cluster region [OCCR]) (P=.10); but that higher incidence was not statistically significant. There was significant evidence that age at diagnosis of breast cancer varied by mutation (P<.001), although only 8% of the variance in age at diagnosis could be explained by the specific mutation, and there was no evidence of family-specific effects. When the age at diagnosis of the breast cancer cases was examined by OCCR, cases associated with mutations in the OCCR had a significantly older mean age at diagnosis than was seen in those outside this region (48 years vs. 42 years; P=.0005).

Consortium study on 1280 breast carcinomas: allelic loss on chromosome 17 targets subregions associated with family history and clinical parameters

The pattern of loss of heterozygosity (LOH) on chromosome 17 in human breast cancer is complicated and shows many different regions of loss. In an attempt to narrow down the relevant regions of LOH on chromosome 17, we have studied the deletion pattern and its association with clinical parameters in 1280 breast carcinoma-venous blood lymphocyte pairs. In total, 42 different chromosome 17 loci were investigated, and between 25 and 625 cases were analyzed at each locus. The frequency of LOH observed on the p arm was much higher than that observed on the q arm. The opposite effect was observed in 52 ovarian cancer cases investigated, with less LOH on 17p than on 17q. Patterns of loss consistent with interstitial and terminal deletions, as well as loss of either the p or q arm or monosomy 17 were observed. To determine whether loss at particular loci may be associated with biological features of breast tumors, clinical data including age of onset, family history of breast cancer, tumor histopathology, tumor size, estrogen receptor (ER) status, and occurrence of lymph node or distant metastases were collected for each case. Overall, large-sized, ER-negative, lymph node-positive ductal tumors showed the highest frequencies of LOH, with ER-negative and ductal tumors showing LOH for markers along the majority of the chromosome. Eight regions of chromosome 17 appear to be associated with human breast cancer, two on 17p and six on 17q. These regions were not necessarily in the areas exhibiting the highest frequencies of LOH but were defined by interstitial and terminal deletions in multiple independent cases. Seven of these regions showed statistically significant differences in LOH associated with clinical parameters. These data strongly suggest that loci on chromosome 17 may determine aspects of tumor presentation and disease behavior in human breast cancer and pinpoint candidate tumor suppressor gene loci.

Regulation of the signal transduction program by drugs

The purpose of this paper was to clarify critical aspects of the behavior of signal transduction activity in normal and cancer cells. 1. Signal transduction activity in the conversion of phosphatidylinositol through PI and PIP kinases and PLC to IP3 is regulated at multiple sites. In liver, hepatomas and human carcinomas PIP kinase is the rate limiting enzyme and PLC activity is present in great excess. 2. The steady-state signal transduction activity as measured by the three enzyme activities and IP3 concentration was markedly up-regulated in rat hepatomas of different growth rates. The steady-state specific activities of the three signal transduction enzymes were elevated in ovarian carcinomas as compared to normal ovary. Increased enzyme activities were also observed in human breast carcinoma cells as compared to normal human breast parenchymal cells. In breast, ovarian and rat hepatoma cells as they go through lag, log and plateau phases, IP3 concentration in the early lag phase increased 4.5- to 20-fold and PI and PIP kinase activities peaked in mid-log phase. These events returned to baseline levels in the plateau phase. PLC activity did not change. 3. The bone marrow PI and PIP kinase activities in 3-day starvation were decreased to 13% and IP3 concentration was reduced to 24%; at 1-day refeeding they returned to normal. PLC activity changed little. These alterations are in line with the rapid t1/2 degradation rates (12 min) of PI and PIP kinases observed in studies with cycloheximide. By contrast, PLC has a long half-life. 4. The molecular action of tiazofurin entails inhibition of IMP DH activity, decrease in GTP and IP3 concentrations, reduction of ras and myc oncogene expression, and signal transduction enzyme activities. These events are followed by induced differentiation and apoptosis. There are also decreases in enzyme activities which have rapid turnover, including TdR kinase, dTMP synthase, and GPRT. In vitro studies indicated that these events are abrogated by addition of guanine which restores GTP concentrations. Therefore, most or all these events were brought about by the reduced GTP concentration in the tiazofurin target cells. 5. Quercetin and genistein are able to inhibit PI and PIP kinase activities and reduce IP3 concentration in vivo and in tissue culture systems. These flavonoids are also inhibitors of cell proliferation and clonogenic ability in rat hepatoma 3924A and in human OVCAR-5 and MDA-MB-435 cells. Quercetin down-regulated the expression of c-myc and Ki-ras oncogenes and led to induced differentiation and apoptosis in K562 cells. Genistein reduced IP3 concentration in vivo and in the tissue culture system. Genistein is antiproliferative and has cytototoxicity in human carcinoma cells. All three drugs, tiazofurin, quercetin and genistein, act, in part at least, through depression of cellular IP3 concentration although the mechanisms may not be identical. 6. Quercetin and genistein, which attack different targets and different phases of the cell cycle, proved to be synergistic in OVCAR-5 cells. The impact of tiazofurin, genistein and quercetin is of interest because the drugs crucially inhibit the display of the neoplastic program of cells and lead to induced differentiation and apoptosis.

Molecular mechanisms in the antiproliferative action of quercetin

A single treatment with quercetin (5.5 microM), a plant flavonoid, activated both apoptosis and differentiation programs in K562 human leukemia cells. K562 cells expressed commitment to apoptosis after 1 h exposure, however, at least 12 h of drug exposure was needed to induce differentiation. Early (1 h) down-regulation of the c-myc and Ki-ras oncogenes and rapid reduction of inositol-1,4,5-trisphosphate (IP3) concentration (IC50 = 9 microM, 1 h incubation) are part of the antiproliferative action of quercetin and appear to relate to induction of differentiation and/or apoptotic program of K562 leukemia cells treated with quercetin.

Allele loss from large regions of chromosome 17 is common only in certain histological subtypes of ovarian carcinomas

Using a panel of ten polymorphic markers, we examined the frequency of loss of heterozygosity (LOH) on chromosome 17 in 55 sporadic ovarian tumours. LOH on 17p and 17q was observed to be 50% and 62% respectively. LOH at D17S5 was detected in 24/36 (67%) of malignant cases and in 19/43 (44%) at TP53; the marker D17S855 intragenic to the BRCA1 gene showed allele loss in 50% (20/40) cases. The data presented here suggest that loss of the whole chromosome 17 is a relatively frequent event (30%) in ovarian carcinomas and this observation is especially frequent for serous, transitional cell and anaplastic histological subtypes. Mucinous and endometrioid ovarian tumours showed only short interstitial deletions (4/11, 36%). The overall frequency of the short deletions was relatively low (7/43, 16%) in our panel of carcinomas. Amplification of c-erbB-2/neu oncogene was detected in 32% (11/34) of the carcinomas tested; the gene was amplified only in those histological subtypes in which high incidence of LOH on chromosome 17 was observed, and was associated with advanced stages of the disease. We conclude that different histological types of tumour may have different aetiological mechanisms, and tumour-suppressor genes on chromosome 17 might be associated specifically with serous and transitional cell ovarian carcinomas.

Molecular mechanisms in the antiproliferative action of taxol and tiazofurin

The molecular antiproliferative effects of taxol and tiazofurin were studied in human K562 leukemia, and in MCF-7 breast and OVCAR-5 ovarian carcinoma cell cultures. A single treatment with taxol (2 to 100 nM) or tiazofurin (5 to 20 microM) on K562 leukemia cells resulted in both a differentiation program and apoptosis in the same cell culture. Tiazofurin proved to be the most potent inducer of differentiation among the inducers, however, taxol had a major impact on induction of the alterations characteristic of apoptosis. The antiproliferative effect of tiazofurin was mediated by 37 to 85% inhibition of IMP dehydrogenase activity. Both the differentiation and apoptosis induced by tiazofurin were dependent on GTP supply. The induction of differentiation and/or apoptosis was mediated by downregulation of c-myc and Ki-ras oncogenes in all three cell lines treated with tiazofurin (by 2 hr) or taxol (by 24 hr). Combined treatments with tiazofurin and taxol exerted a schedule-dependent, antiproliferative interaction in the cell lines studied. Synergistic inhibition of cell proliferation was observed when cells were pretreated with tiazofurin (10 to 15 microM) for at least 12 hr, then taxol (5 to 15 nM) was added.

Quercetin down-regulates signal transduction in human breast carcinoma cells

Signal transduction activity was markedly elevated in cancer cells as shown by the increased activity of enzymes utilizing 1-phosphatidylinositol, PI (PI 4-kinase and PI-4-phosphate 5-kinase) for the production of the second messenger inositol 1,4,5-trisphosphate, IP3, in rat hepatomas (Cancer Res. 54: 2611;5574, 1994) and in human ovarian and breast carcinoma cells (Life Sci. 55:1487, 1994). Quercetin, a flavonoid, in human breast carcinoma MDA-MB-435 cells produced growth inhibition (IC50 = 55 microM) and cytotoxicity (LC50 = 26 microM). Quercetin inhibited PI kinase activity in extracts of breast carcinoma cells (IC50 = 6 microM) and in cultured cells (IC50 = 10 microM) with a minor inhibition of PIP kinase activity. IP3 concentration decreased in parallel with PI kinase activity. In time sequence studies quercetin in breast carcinoma cells brought down PI kinase and IP3 concentration in 60 min to 5 and 6%, respectively; PIP kinase activity was at 63% of controls. The results demonstrate for the first time in proliferating human breast carcinoma cells a reduction by quercetin of the increased capacity for signal transduction, thus providing a novel and sensitive target in cancer cells.

Linkage of reduction in 1-phosphatidylinositol 4-kinase activity and inositol 1,4,5-trisphosphate concentration in human ovarian carcinoma cells treated with quercetin

Quercetin inhibited 1-phosphatidylinositol (Pl) 4-kinase, EC 2.7.1.67 (Pl kinase) activity in a concentration-dependent manner (IC50 = 4 microM) in particulate extracts from human ovarian carcinoma. In OVCAR-5 cells quercetin produced growth inhibition (IC50 = 63 microM) and cytotoxicity (LC50 = 17 microM). The growth inhibition by quercetin was accompanied by an 80% decrease in Pl kinase activity and a 65% decrease in the concentration of the second messenger, inositol 1,4,5-trisphosphate (IP3). When human OVCAR-5 cells were plated and expressed their neoplastic proliferative program in the log phase, Pl kinase and Pl 4-phosphate 5-kinase, EC 2.7.1.68 (PIP kinase) activities coordinately increased to a peak of 5.8- and 4.5-fold, respectively. The results demonstrate for the first time inhibition by quercetin of the enhanced capacity for operation of signal transduction in human ovarian carcinoma cells, thus providing a novel target in cancer cells.

Synergistic action of taxol with tiazofurin and methotrexate in human breast cancer cells: schedule-dependence

Taxol (paclitaxel, (NSC 125973)) is an active agent in the treatment of metastatic carcinoma of the breast; however, positive responses were observed in only about 60% of cases. Therefore, drug combinations which might improve the effectiveness are required. Since tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide, NSC 286193), methotrexate (MTX) and taxol exert their anticancer action in different phases of the cell cycle and have different biochemical targets, we tested the hypothesis that tiazofurin and methotrexate might by synergistic with taxol. MDA-MB-435 human breast cancer cells were grown in monolayer in flasks. In the growth inhibition assay for tiazofurin, methotrexate and taxol the IC50s were 12.5, 0.5 and 0.016 microM, respectively, and in the clonogenic assay 4.5, 0.065 and 0.004 microM. When taxol was given 6 hr before tiazofurin, antagonism was observed and summation was seen when drugs were given simultaneously. Synergism was obtained in both growth inhibitory and clonogenic assays when tiazofurin was followed 12 hr later by taxol. Methotrexate and taxol had an antagonistic effect when they were added simultaneously or when taxol was given 6 hr before methotrexate; summation was observed when taxol was followed 12 hr later by methotrexate. Synergistic action was obtained in the clonogenic assay when methotrexate was followed 12 hr later by taxol. The protocols yielding synergism should be of value in the design of taxol-based clinical trials for breast cancer.

Inhibition by tiazofurin of inosine 5′-phosphate dehydrogenase (IMP DH) activity in extracts of ovarian carcinomas

Cancer cells have an increased ability to synthesize GTP (guanosine triphosphate) because of increased activity of IMP DH (inosine 5'-phosphate dehydrogenase, EC 1.1.1.205). Because IMP DH activity is rate limiting for de novo biosynthesis of GTP, this enzyme was suggested as a sensitive target for chemotherapy. Tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide) is converted in the cells into the active metabolite, TAD, (thiazole-4-carboxamide adenine dinucleotide) which potently inhibits IMP DH activity. By adding TAD to tissue extracts one can determine the extent of inhibition of IMP DH. We applied the IMP DH assay method to extracts of normal ovaries (N = 11) and epithelial ovarian carcinomas (N = 10). The IMP DH activity (mean +/- SE) in ovarian carcinoma was 21.1 +/- 5.8 which was markedly higher than that observed in normal ovaries (2.9 +/- 0.7 nmol/hr/mg protein) (P < 0.05%). The inhibition by TAD of IMP DH activity in ovarian carcinomas (N = 4) was 81%. The results indicate that IMP DH activity is elevated sevenfold in ovarian carcinomas as compared to normal ovary and can be inhibited by exposure to tiazofurin (TAD). Similar high IMP DH activity and inhibition of the activity by TAD was observed in patients with chronic granulocytic leukemia in blast crisis among whom 70 to 80% remissions were reported. Since there is increased IMP DH activity in human ovarian carcinomas and in OVCAR-5 cells and tiazofurin and TAD inhibit IMP DH activity of these cells and the proliferation of human ovarian carcinoma xenografts in the mouse, tiazofurin may merit serious consideration for a Phase II trial for patients with recurrent/refractory epithelial ovarian carcinoma.

AZT: a biochemical response modifier of methotrexate and 5-fluorouracil cytotoxicity in human ovarian and pancreatic carcinoma cells

In ovarian and pancreatic carcinoma cell lines, the activity of the salvage enzyme, thymidine kinase (EC 2.7.1.21), was 2- to 13-fold higher than that of the key enzyme of thymidylate de novo biosynthesis, thymidylate synthase (dTMP synthase, EC 2.1.1.45). AZT (3'-azido-3'-deoxythymidine, zidovudine) competitively inhibited thymidine kinase activity in extracts of human ovarian and pancreatic carcinoma cells, with Dixon plots yielding Ki = 1.1 microM in both cell lines. AZT (20 microM) yielded synergistic cytotoxicity with methotrexate (0.4 microM) in human pancreatic carcinoma cells in clonogenic assay and also with methotrexate (0.02 microM) in human ovarian carcinoma cells, as measured by cell counts. Thymidine (10 microM) and hypoxanthine (100 microM) reversed these inhibitions. AZT (20 or 40 microM) also provided synergistic cytotoxicity with 5-fluorouracil (0.5 and 1.0 microM) in human pancreatic carcinoma cells in clonogenic assay. These studies suggest a new role for AZT, which, as an inhibitor of thymidine salvage, should be useful as a biochemical response modifier to provide a synergistic clinical anticancer impact on de novo biosynthesis of thymidylates in conjunction with methotrexate or 5-fluorouracil.

Cytogenetic analyses of three papillary carcinomas and a follicular adenoma of the thyroid

Cytogenetic data of three papillary carcinomas and a follicular adenoma using direct preparations or cell cultures or both after 7 to 60 days in vitro are presented. Although karyotype of the follicular adenoma proved completely normal, in each of the three papillary carcinomas a modal chromosome number in the diploid range and a deleted 11q were observed. In case 1 the del(11)(q23) was associated with rearrangement of chromosome 1 and other marker chromosomes. Our results suggest that 11q deletion may be specific for papillary carcinoma of the thyroid.

Clinical and molecular impact of inhibition of IMP dehydrogenase activity by tiazofurin

The impact of tiazofurin on inhibition of IMP dehydrogenase was discussed at the clinical and molecular levels. 1. Evidence was provided for the role of IMP dehydrogenase and guanylates in the expression of the neoplastic program in cancer cells with particular relevance to human leukemic cells. 2. The argument for expecting an impact of tiazofurin in human myelocytic cells was provided. 3. Similarity of the kinetics of human leukemic cell IMP dehydrogenase to the rat hepatoma enzyme was documented. 4. New evidence was provided for the role of salvage in chemotherapy and the function of hypoxanthine in inhibiting guanine salvage. 5. The action of tiazofurin and retinoic acid was reported in HL-60 leukemic cells. 6. The effect of tiazofurin and retinoic acid on proliferation and cytotoxicity was outlined for hepatoma 3924A cells. 7. The effect of guanine on induced differentiation by tiazofurin and retinoic acid was examined. 8. Biochemical basis was provided for the lack of development of resistance in patients treated with tiazofurin. 9. Presumptive evidence was provided that tiazofurin treatment induced differentiation of leukemic cells in the patients. 10. The molecular biology of tiazofurin-induced differentiation in K-562 cells was reviewed with the possible relevance to clinical treatment that tiazofurin might also act through down-regulation of ras oncogene.

Significance of purine salvage in circumventing the action of antimetabolites in rat hepatoma cells

The flux activities of de novo and salvage purine synthesis were compared in rat hepatoma 3924A cells in various growth phases. The initial rate assays of [14C]adenine, [14C]hypoxanthine, and [14C]guanine incorporation yielded Michaelis-Menten kinetics with Kms of 5, 7, and 7 microM, respectively. After replating plateau phase cells in lag and log phases the activity of purine de novo pathway increased 4.5- to 8-fold with a preferential rise in guanylate synthesis, whereas purine salvage activities increased only 1.6- to 2.1-fold. However, for the syntheses of IMP, AMP, and GMP, the activities of purine salvage pathways were 2- to 7-fold, 5- to 28-fold, and 2- to 32-fold higher than those of the de novo purine pathway. Treatment of cells with acivicin, an inhibitor of the activity of amidophosphoribosyltransferase, phosphoribosylformylglycinamidine synthase, and GMP synthase, inhibited the flux activities of de novo purine, adenylate, and guanylate syntheses to 37, 73, and 3% of the controls and decreased the concentration of GTP to 42%; the concentration of ATP did not change and that of 5-phosphoribosyl 1-pyrophosphate increased 3.1-fold. Under these conditions the activities of salvage synthesis from hypoxanthine and guanine were enhanced 2.5-fold. Treatment of hepatoma cells with IMP dehydrogenase inhibitors, tiazofurin, ribavirin, and 4-carbamoylimidazolium 5-olate, to block de novo guanylate synthesis accelerated the flux activity of guanine salvage pathway. The higher capacity of purine salvage pathway than that of the de novo one and the further rise of the activity in response to the drugs targeted against the de novo pathway highlight the important role salvage synthesis might play in circumventing the impact of antimetabolites of de novo purine synthesis in cancer chemotherapy.

Induction of erythroid differentiation and modulation of gene expression by tiazofurin in K-562 leukemia cells

Tiazofurin (2-beta-D-ribofuranosyl-4-thiazole-carboxamide; NSC 286193), an antitumor carbon-linked nucleoside that inhibits IMP dehydrogenase (IMP:NAD+ oxidoreductase; EC 1.1.1.205) and depletes guanylate levels, can activate the erythroid differentiation program of K-562 human leukemia cells. Tiazofurin-mediated cell differentiation is a multistep process. The inducer initiates early (less than 6 hr) metabolic changes that precede commitment to differentiation; among these early changes are decreases in IMP dehydrogenase activity and in GTP concentration, as well as alterations in the expression of certain protooncogenes (c-Ki-ras). K-562 cells do express commitment-i.e., cells exhibit differentiation without tiazofurin. Guanosine was effective in preventing the action of tiazofurin, thus providing evidence that the guanine nucleotides are critically involved in tiazofurin-initiated differentiation. Activation of transcription of the erythroid-specific gene that encodes A gamma-globin is a late (48 hr) but striking effect of tiazofurin. Down-regulation of the c-ras gene appears to be part of the complex process associated with tiazofurin-induced erythroid differentiation and relates to the perturbations of GTP metabolism.

Aggressive infantile myofibromatosis: report of a case of a clinically progressive congenital multiple fibromatosis

We report a case of congenital multiple fibromatosis (infantile myofibromatosis) showing the typical spindle-cellular proliferation with prominent vascularity on light microscopical observations. Electron microscopy showed the abundance of fibroblasts with conspicuous collagen and reticulin fibers together with numerous cells sharing the characteristics of both fibroblasts and smooth muscle cells (myofibroblasts). Neither visceral involvement nor ossification has been detected during the 4-year-long follow-up period. However, the clinical course has shown a slow, continuous, protracted though destructive proliferation of subcutaneous myofibroblastic nodules. These findings are contrasted with previous reports that claimed that the presence of myofibroblasts indicates benign behavior and results in the regression of fibromatous lesions.

Modulation of IMP dehydrogenase activity and guanylate metabolism by tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide)

Tiazofurin, a C-nucleoside, was cytotoxic in hepatoma 3924A cells grown in culture with an LC50 = 7.5 microM. In the culture, a closely linked dose-related response of tumor cell-kill and depletion of GTP pools was observed after tiazofurin treatment. In rats carrying subcutaneously transplanted hepatoma 3924A solid tumors, a single intraperitoneal injection of tiazofurin (200 mg/kg) caused a rapid inhibition of IMP dehydrogenase (EC 1.2.1.14) activity and depleted GDP, GTP, and dGTP pools in the tumor; concurrently, the 5-phosphoribosyl 1-pyrophosphate (PRPP) and IMP pools expanded 8- and 15-fold, respectively. Tiazofurin decreased tumoral IMP dehydrogenase activity and dGTP pools in a dose-dependent manner over a range of 50-200 mg/kg; by contrast, the depletion of GTP and the accumulation of IMP and PRPP pools were near maximum at 50 mg/kg. The increase in PRPP pools may be attributed to an inhibition by IMP of the activity of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8). The IMP dehydrogenase activity and the pools of ribonucleotides returned to the normal range by 24-48 h after the single injection of tiazofurin. However, the markedly depleted dGTP pools remained low for 72 h. Tiazofurin treatment resulted in significant anti-tumor activity in rats inoculated with hepatoma 3924A. The decrease in GTP levels and particularly the sustained depletion in the dGTP pools may explain, in part at least, the chemo-therapeutic action of tiazofurin on hepatoma 3924A. This is the first report showing that a marked therapeutic response was achieved against rapidly growing hepatoma 3924A by treatment with a single anti-metabolite.

Utilization of dietary urea in rainbow trout

Experiments were conducted to examine the potential utilization of dietary urea by rainbow trout. A control diet and two diets supplemented with 1 and 3% of urea were fed to fish. Postprandial levels of urea and ammonia in blood plasma, and postprandial excretion of these metabolites were followed during 24 h. Apparent digestibility of urea in rainbow trout was very high (greater than 98%). Maximum values of urea levels in plasma were reached 6 h (32.3 +/- 10.2 micrograms/ml) after a meal in the control fish and respectively 6 h (83.4 +/- 18.4 micrograms/ml) and 8 h (250.3 +/- 96.1 micrograms/ml) after a meal in trout fed 1 and 3% urea diets. Peaks of urea excretion rates appeared 7-9 h after meal, coinciding with the highest circulating urea concentration. Total daily urea excretion amounted to 5.53, 10.43 and 33.80 mg urea N/100 mg N intake in trout fed the control, 1 and 3% urea diets, respectively. It is concluded that the dietary urea is readily absorbed in the digestive tract of trout but is totally excreted thus leading to no beneficial effect on nitrogen balance. This excretion of urea also takes place passively without any increase in energy demands.

Cytotoxic and cell kinetic effects of 3,4,5-trihydroxybenzohydroxamic acid (VF 122) in hepatoma 3924A cells

3, 4, 5-Trihydroxybenzohydroxamic acid (VF 122), an inhibitor of ribonucleotide reductase, killed rat hepatoma 3924A cells in tissue cultured after 7 days of incubation. A concentration of 15 microM caused 50% inhibition of colony-forming ability (IC50). Under the same conditions, hydroxyurea, also an inhibitor of ribonucleotide reductase, had an IC50 of 52 microM. Treatment for 1 hr with VF 122 of exponentially growing culture resulted in a biphasic exponential dose-response curve (Do = 0.5 mM, IC50 = 0.75 mM, and Do = 1.8 mM, IP = 0.8 mM). In plateau-phase cells, a threshold exponential curve was obtained (Do = 2.2 mM, Dq = 1.7 mM, and IC50 = 2.7 mM). Exponentially growing hepatoma 3924A cells were more sensitive to VF 122 than were plateau-phase cultures. In contrast, hydroxyurea killed only exponentially growing 3924A hepatoma cells, exhibiting an exponential plateau dose-response curve without achieving achieving an IC50 value at concentrations from 1 to 200 mM. In synchronized cultures, VF 122 (1 MM for 1 hr) was toxic for cells in mid and late G1 phase, in early and mid S phase, and, to a lesser degree, in G2 phase, Hydroxyurea (10 mM for 1 hr) killed cells only in S phase. Proliferating and resting hepatoma 3924A cells recovered from sublethal and potentially lethal damage induced by VF 122.