Cancer Research SABCS Telomeres
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Cancer Research Clinical Cancer Research
Cancer Epidemiology Biomarkers & Prevention Molecular Cancer Therapeutics
Molecular Cancer Research Cancer Prevention Research
Cancer Prevention Journals Portal Cancer Reviews Online
Annual Meeting Education Book Meeting Abstracts Online
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ramus, S. J.
Right arrow Articles by Gayther, S. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ramus, S. J.
Right arrow Articles by Gayther, S. A.
[Cancer Research 63, 417-423, January 15, 2003]
© 2003 American Association for Cancer Research

Molecular Biology and Genetics

BRCA1/2 Mutation Status Influences Somatic Genetic Progression in Inherited and Sporadic Epithelial Ovarian Cancer Cases1

Susan J. Ramus2, Paul D. P. Pharoah, Patricia Harrington, Carole Pye, Bruce Werness, Lynda Bobrow, Ayse Ayhan, Dagan Wells, Ami Fishman, Martin Gore, Richard A. DiCioccio, M. Steven Piver, Alice S. Whittemore, Bruce A. J. Ponder and Simon A. Gayther3

Department of Oncology, Strangeways Research Laboratories, Cambridge, United Kingdom [S. J. R., P. D. P. P., P. H., C. P., B. A. J. P.]; Department of Pathology, Inova Fair Oaks Hospital, Fairfax, Virginia [B. W.]; Department of Pathology, Addenbrookes Hospital, Cambridge, United Kingdom [L. B.]; Cancer Research United Kingdom Translational Oncology Laboratory, John Vane Science Centre, Charterhouse Square, London, United Kingdom [A. A., S. A. G.]; University College London, Department of Obstetrics and Gynaecology, London, United Kingdom [D. W.]; Department of Obstetrics and Gynaecology, Meir Hospital, Sapier Medical Centre, Meyir Hospital, Kfar-Saba, Israel [A. F.]; Department of Clinical Oncology, Royal Marsden Hospital, London, United Kingdom [M. G.]; Department of Cancer Genetics Roswell Park Cancer Institute Buffalo, New York [R. D., M. S. P.]; and Department of Health Research and Policy, Stanford University School of Medicine, Stanford, California [A. S. W.]


   ABSTRACT
Top
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Metaphase comparative genomic hybridization was used to analyze the spectrum of genetic alterations in 141 epithelial ovarian cancers from BRCA1 and BRCA2 mutation carriers, individuals with familial non-BRCA1/2 epithelial ovarian cancer, and women with nonfamilial epithelial ovarian cancer. Multiple genetic alterations were identified in almost all tumors. The high frequency with which some alterations were identified suggests the location of genes that are commonly altered during ovarian tumor development. In multiple chromosome regions, there were significant differences in alteration frequency between the four tumor types suggesting that BRCA1/2 mutation status and a family history of ovarian cancer influences the somatic genetic pathway of ovarian cancer progression. These findings were supported by hierarchical cluster analysis, which identified genetic events that tend to occur together during tumorigenesis and several alterations that were specific to tumors of a particular type. In addition, some genetic alterations were strongly associated with differences in tumor differentiation and disease stage. Taken together, these data provide molecular genetic evidence to support previous findings from histopathological studies, which suggest that clinical features of ovarian and breast tumors differ with respect to BRCA1/2 mutation status and/or cancer family history.


   INTRODUCTION
Top
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Mutations in the BRCA1 and BRCA2 genes are responsible for about half of all families containing two or more cases of epithelial ovarian cancer in close relatives and most families in which multiple cases of ovarian and breast cancer occur together (1, 2, 3, 4) . Ovarian and breast tumors from mutation carriers frequently show loss of the normal allele (detected by microsatellite analysis), suggesting that both genes behave as tumor suppressors (5 , 6) .

Several studies indicate that the histological and clinical features of ovarian and breast cancers vary with respect to BRCA1/2 mutation status and a family history of the disease. In breast cancer, histopathological characteristics such as grade, proliferation rate, S-phase fraction, and mitotic and aneuploid indices may differ either between BRCA1 and BRCA2 tumors or when compared with non-BRCA1/2 tumors (7, 8, 9) . In ovarian cancer, one study found a higher proportion of serous cystadenocarcinomas in familial ovarian cancers (89%) compared with nonfamilial tumors (49%; Ref. 10 ). Other reports also indicate that BRCA1 tumors are mostly serous adenocarcinomas (9 , 11) . Finally, some studies suggest that BRCA1/2 mutation status may influence patient survival, although there is disagreement between studies as to whether BRCA1 carriers have a better or worse survival than controls (10, 11, 12, 13) .

Taken together, these data suggest that BRCA1/2 mutation status may influence the clinical characteristics and outcome in breast and ovarian cancers. However, mutations in these genes alone are unlikely to account for all of the variation observed; tumor formation results from an accumulation of somatic genetic alterations in several different genes, of which many may influence tumor phenotype. In support of this, some studies have shown association between the clinical characteristics of tumors and multiple differences in gene expression (14) .

Previously, we have established the BRCA1 and BRCA2 mutation status in 288 epithelial ovarian cancer families (Ref. 3 ; unpublished data). The purpose of this study was to establish whether the spectrum of somatic genetic events, which may influence tumor phenotype during ovarian cancer development, differs with respect to BRCA1/2 mutation status and/or a family history of the disease. To do this, we have compared the frequencies of genomic alterations identified using metaphase CGH4 between ovarian tumors from BRCA1 and BRCA2 mutation carriers, familial cases in which no BRCA1/2 mutation could be identified and sporadic cases.


   MATERIALS AND METHODS
Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Patient Material.
Paraffin-embedded epithelial ovarian tumors from 141 individuals were analyzed in this study. Of these, 108 cases were from families containing two or more first-degree relatives with ovarian cancer, identified from the United Kingdom Coordinating Committee on Cancer Research (3) and United States Gilda Radner (15) familial ovarian cancer registries. All cases have been analyzed for germ-line mutations throughout the coding region and splice site boundaries of the BRCA1 and BRCA2 genes (Ref. 3 ; unpublished data). Mutations in BRCA1 were present in 46 individuals from 32 families and in BRCA2 in 18 individuals from 11 families. Also included in the study were five tumors from a hospital-based collection of ovarian cancer cases from Israel, which carried the Ashkenazi Jewish founder mutation (6174delT) in BRCA2 (13) . No identifiable BRCA1/2 mutation was present in 44 cases from 32 families. Sporadic tumors (i.e., cases with no reported first or second-degree relatives with ovarian cancer) from 28 individuals, who had taken part in a hospital-based collection of ovarian cancer cases at the Royal Marsden Hospital (London, United Kingdom) were also analyzed. These cases have previously been analyzed for germ-line mutations in the BRAC1 gene; none were identified (16) .

For each tumor, histological sub-type and tumor grade was established by specialist pathology review (B. W., L. B., A. A.). Information on disease stage, where available, was obtained from hospital records. Tumors from sporadic cases were selected so that the distribution of different histological subtypes was similar to those in familial cases. In total, 59.5% of tumors were of serous histology (ranging from 52–63% between the four groups), 10.5% of tumors were endometrioid histology (range, 5–14%), 18% were either undifferentiated tumors or carcinomas of unspecified histology (range, 14–26%), and the remainder (12%; range, 9–18%) were a mixture of rare histological subtypes, including tumors of mucinous, clear cell, and mixed histology.

Metaphase CGH Analysis.
Pathology examination of tissue sections identified areas of tumor epithelium, which were microdissected away from surrounding tissues. DNA was extracted after proteinase K digestion. To improve the sensitivity of metaphase CGH analysis, only regions of tissue containing >=70% tumor epithelium were dissected. The same normal DNA sample, which was extracted from normal archival tissue, was used as the reference for all of the CGH analyses.

Whole genome amplification was performed using degenerate oligonucleotide priming PCR; DNA fragments were labeled either with biotin 16-dUTP (normal DNA), or digoxigenin-11-dUTP (tumor DNA; Roche). After amplification, tumor and normal samples were combined with 20 µg of human CoT-1 DNA, denatured, and allowed to preanneal before hybridizing to normal, male metaphase chromosome spreads for 72 h at 37°C. After hybridization, biotin-labeled DNA was detected using avidin-Texas Red (Vector Laboratories) and digoxigenin-labeled DNA detected using antidigoxigenin-fluorescein Fab fragments (Roche). Slides were counterstained with 4',6-diamidino-2-phenylindole to identify the chromosomes. Slides were viewed on a Zeiss fluorescence microscope. Digital images of metaphase spreads were captured using Quips SmartCapture VP and analyzed using Quips CGH Kayotyper and Interpreter software (Vysis).

For each sample, at least 10 different metaphase chromosome spreads were examined and a mean value for the ratio of the green signal (tumor DNA) to red signal (normal DNA) calculated along the length of each chromosome. To establish threshold levels for the recording of loss and gain in tumors, we performed metaphase CGH analyses using two different normal DNA samples; this provided an indication of the normal variation in the ratios of the two fluorochromes for each chromosome. No genetic variation identified in normal-normal CGH comparisons reached the thresholds for loss or gain that were subsequently used for the analysis of tumor samples. The threshold for recording genomic gain was a green to red ratio > 1.2, for genomic loss a green to red ratio < 0.85, and for amplification a green to red ratio > 1.5.

Metaphase CGH Control Analyses.
The following controls were performed to test the efficacy of metaphase CGH data: (a) CGH was repeated on a random series of 10 samples to ensure that the spectrum of alterations detected in each tumor sample was reproducible. (b) CGH was repeated on 15 samples using reverse labeling (normal samples labeled with digoxigenin, tumor samples with biotin). In all cases, the data established for inverse and standard CGH analyses were concordant. (c) Thirty-five samples were analyzed by LOH microsatellite analysis to establish concordance/discordance with deletions identified by CGH. Microsatellite markers at nine regions on different chromosome arms were informative for 83/95 deletions identified by CGH; LOH and CGH data were concordant for 76/83 deletions.


   RESULTS
Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Frequency of Somatic Alterations.
Metaphase CGH identified multiple somatic alterations in 137 of the 141 tumors. On average, 21.4 alterations (95% confidence interval, 19.9–22.9) were identified per tumor. No significant differences were observed in the number of genetic alterations identified between BRCA1, BRCA2, familial non-BRCA1/2, and sporadic tumors.

Table 1Citation summarizes the frequencies with which genetic alterations were identified for each chromosome arm. Several alterations occurred with a particularly high frequency (in 42–76% of all tumors); these were loss on chromosomes 4q, 5q, 6q 13q, 18q, and X and gain on chromosomes 1, 3q, 6p, 7q, 8q, 19q, and 20q. Several regions of relatively frequent loss or gain (in >30% of all tumors) were also identified. For most alterations, we were able to define single, critical regions in common between tumors. In some cases it was possible to define more than one region of interest (Table 1)Citation . Seemingly, some alterations extend for most of the length of a chromosome suggesting a change in chromosome number rather than an interstitial alteration; these include loss of chromosomes 4, 13, 14, 15, and X and gain of chromosomes 1, 12, 19, and 20. We cannot say whether changes in chromosome number and interstitial alterations on the same chromosome represent the same gene targets.


View this table:
[in this window]
[in a new window]

  		Table 1 Frequencies of loss and gain for each chromosome arma

 
High levels of amplifications were identified at several sites throughout the genome. In some instances, the same region of high-level amplification was common to multiple tumors, which possibly indicates the location of a single gene target. In general, high-level amplifications were not frequent events. However, they tended to occur in regions that also showed frequent gain, which may suggest a shared target (Table 2)Citation . The most frequent region of high-level amplification, which was identified in 40% of tumors, occurred on chromosome 8q22-qter. Putative candidate genes in regions of amplification and in regions of frequent loss and gain (occurring in >50% of tumors) are listed in Table 2Citation . These genes were selected because they have all previously been shown to have a role in cancer.


View this table:
[in this window]
[in a new window]

  		Table 2 Cancer-associated genes and putative targets of located within the most frequent regions of loss, gain and amplification identified in this studya

 
Different Patterns of Somatic Alteration Associated with BRCA1/2 Mutation Status and a Family History of Ovarian Cancer.
We used two different approaches to determine whether the pattern of somatic genetic alterations during tumor development differs between BRCA1, BRCA2, familial non-BRCA1/2, and sporadic ovarian cancers. Firstly, we performed a systematic comparison of the frequency of genetic alterations between the four tumor groups. Secondly, we performed hierarchical cluster analysis to identify alterations that tended to occur together during tumor development. For the purpose of these analyses, we divided the genome into 100 nonoverlapping regions of similar size based on the 4',6-diamidino-2-phenylindole-banding on the CGH profile and recorded the presence of loss or gain at every region for each tumor.

We compared the frequency of alteration at all regions by tumor type using an overall {chi}2 test on 3 degrees of freedom. Where the statistical significance of the overall {chi}2 was P < 0.2 and the frequency of the alteration was >=15% for at least one tumor group, we carried out pair-wise comparisons of the frequency of the change; each tumor group was compared against each other and against the other tumor groups combined (see Table 3Citation ).


View this table:
[in this window]
[in a new window]

  		Table 3 Comparison between the frequencies of somatic alteration identified at 20 different regions in BRCA1 and BRCA2-associated, familial non-BRCA1/2, and sporadic ovarian cancersa

 
Significant differences in the frequency of loss or gain between one or more groups of tumor were identified at 20 different chromosome regions; in total, 41 significant differences were observed between the four groups (Table 3)Citation . Notably, deletions of the region containing the BRCA1 gene (17q12-21) were significantly more frequent in tumors from BRCA1 mutation carriers than in non-BRCA1 tumors (P = 0.014). Similarly, deletions of the region containing the BRCA2 gene (13q12-13) were significantly more frequent in tumors from BRCA2 mutation carriers than in non-BRCA2 tumors (P = 0.006). This is consistent with data from LOH studies, which indicates that deletion of the wild-type BRCA1 or BRCA2 allele is a frequent and nonrandom event in tumors from mutation carriers.

We performed a hierarchical clustering algorithm, implemented in the program Cluster (17) to distinguish the most critical changes of tumor progression for each of the four tumor types. Cluster analysis was performed separately for each tumor type; this was necessary because many of the more frequent genetic alterations were common to all four groups and a cluster analysis of all tumors grouped together could not differentiate between the groups. These data are illustrated in Fig. 1Citation . For each group, two clusters representing regions of loss and gain were prominent. As expected, there was a tendency for some of the more frequent somatic alterations to cluster together, regardless of BRCA1/2 mutation status or family history. Regions of loss that were common to clusters from three or more groups occurred on chromosomes 4q, 5q, 6q, 13q, and 18q; common regions of gain occurred on chromosomes 1p, 3q, 6p, 8q, 19, and 20.



View larger version (81K):
[in this window]
[in a new window]
[Download PPT slide]
  		Fig. 1. Hierarchical clustering of metaphase CGH data. Analysis was performed separately for BRCA1, BRCA2, familial non-BRCA1, and sporadic tumors. The presence of loss (red), gain (green), or no loss/gain (black) was recorded throughout the genome divided into 100 nonoverlapping regions of similar size. These data are displayed in a matrix format; each column within the matrix represents the spectrum of genetic alterations for a single tumor. For each matrix, the most densely grouped hierarchical cluster of loss and gain has been highlighted and the regions within the cluster described: red typeface refers to regions of loss that occur in clusters from three or more tumor groups; green typeface refers to regions of gain that occur in clusters from three or more tumor groups; black typeface refers to regions of loss or gain that occur in the clusters of only one or two tumor groups.

 
In addition to the frequently occurring alterations, there were several changes that were not common in the clusters of all tumor types, which may indicate differences in the molecular genetic pathways of tumor progression between different tumor types. Significantly, loss of the BRCA1 region appeared in the most prominent cluster in BRCA1 tumors but not in familial non-BRCA1/2 or sporadic tumors. Interestingly, loss at BRCA1 also appears in the most prominent cluster in BRCA2 tumors, even though loss at this locus occurred in only 18% of this tumor type. Other alterations identified in the clusters of one or two, but not all, tumor groups include gains on chromosome 5p and 7q (in BRCA1 and familial non-BRCA1/2 tumor clusters only), loss on X (BRCA2 and sporadic tumors), loss on 17p (BRCA1 and BRCA2 tumors), loss on 3p and gain on 11q (BRCA2 tumors), gain on 2p (familial non-BRCA1/2 tumors), and loss on 9q and gain on 21q (sporadic tumors).

Association between Somatic Alterations and Clinical Characteristics of Ovarian Tumors.
To assess the clinical significance of somatic changes in ovarian cancer, we classified tumors according to histopathological grade and disease stage. Information on grade was available for all except three clear cell carcinomas (138 tumors in total) and on disease stage for 65 tumors. In general, there were fewer genetic alterations in grade 1 tumors (mean, 15.5) than in grade 2 or grade 3 tumors (mean, 22.6 and 21.6 respectively), but this difference was not statistically significant. Neither was there a significant difference in the number of genetic alterations identified in stage I/II (21.1) compared with stage III/IV (21.9) tumors.

We used {chi}2 tests to compare the frequencies of loss and gain throughout the genome with tumors of different grade and stage. In addition, a {chi}2 test for trend was used to assess whether there was a tendency for somatic alterations either to increase or decrease in frequency from grade 1 to grade 3 tumors. These data are summarized in Table 4Citation . Several alterations differed in frequency between tumors of different grade and/or stage. For example, loss at Xcen-q13 was more common in grade 3 tumors compared with grade 1 and 2 tumors (P = 0.002). Loss at 5q14-q22 was more common in grade 2 and 3 tumors compared with grade 1 tumors (P = 0.045), but an increasing trend in frequency from grade 1 to grade 3 tumors was more significant (P = 0.018). Loss on chromosome 5q14-q22 was also associated with later stage disease (P = 0.032) as were gains on chromosomes 21q22-qter (P = 0.027) and 1p32-p34.3 (P = 0.04). Surprisingly, two alterations showed a decrease in frequency with higher grade or later stage; a gain on 22q12-qter was more frequent in tumors of lower grade (P = 0.029; {chi}2 trend P = 0.005), and a loss on 4p15.1-pter was associated with earlier stage (P = 0.005).


View this table:
[in this window]
[in a new window]

  		Table 4 Somatic genetic events in ovarian tumors that are significantly associated with changes in disease stage and tumor grade

 

   DISCUSSION
Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
In this study, metaphase CGH analysis of 141 epithelial ovarian cancers identified multiple, frequently occurring somatic alterations. It is likely that many of these changes represent the location of genes that are critical for ovarian tumor development, although some may simply reflect an accumulation of genetic damage that occurs during tumor progression.

Some of the data from this study are consistent with previous metaphase CGH and LOH studies in ovarian cancer (18, 19, 20) ; for example, regions of common deletion on chromosomes 4p, 6q, 9p, 13q, 18q, and Xp have frequently been identified using LOH analysis (18) . Similarly, a previous study in which metaphase CGH was used to analyze 100 sporadic ovarian tumors identified multiple regions of loss and gain that are consistent with our findings (19) .

However, some of our data differ from previous studies (18, 19, 20) ; for example, there are notable differences in the frequency with which alterations on chromosomes 3q, 5q, 6p, 12q, 17, 19p, 22q, and Xq were detected between this and other studies. Some of the disparity between CGH and LOH data may be explained by differences between the two methods in their ability to resolve genetic alterations; metaphase CGH paints a picture of gross genomic alterations, including changes in chromosome copy number, whereas LOH analysis produces better, locus-specific resolution. However, LOH analysis is limited as a genome wide screen because it requires high-density microsatellite mapping, which is both time consuming to perform and a considerably greater drain on DNA resources compared with CGH. Another reason for some of the differences between this and other metaphase CGH studies could be that whereas most previously published CGH data are from sporadic ovarian cancers only, approximately half of all tumors in this study were from BRCA1/2 mutation carriers and only a fifth from sporadic cases; previous studies in breast cancer suggest that the presence of germ-line BRCA1/2 mutation can influence the pattern of somatic genetic alterations during tumor development (21 , 22) .

We find evidence of a similar influence when the frequencies with which somatic genetic changes in tumors from BRCA1, BRCA2, familial non-BRCA1/2, and sporadic cases are compared. We identified multiple differences between the four tumor groups, which suggests that they differ in some aspects of tumor development. However, we carried out a large number of significance tests, and it is likely that some of these differences are chance occurrences. There were 200 individual comparisons between the four tumor groups and 32 alterations with a P <0.2 were selected for additional analyses in which an additional 320 pair-wise comparisons was performed. Applying the Bonferroni correction to the results of these analyses would require a P of <0.00016 to achieve a conventional level of significance of P < 0.05. The sample size of this study was not large enough to generate such a small P, and indeed the smallest observed P was 0.001. However, we observed 41 pair-wise comparisons with significant differences at the 0.05 level compared with 16 expected if there were no true differences in frequency of alteration between tumor types, and 8 significant differences at the 0.01 level compared with 3 expected. This suggests that a substantial proportion of these differences are real.

This assertion is supported by the observation, as expected, of significant increases in the frequencies of loss at the BRCA1 and BRCA2 loci in tumors from BRCA1 and BRCA2 carriers, respectively. To provide a better indication of the most critical events, we used a hierarchical cluster algorithm to group alterations that tended to occur together. The apparent clustering of a limited number of regions of loss and gain indicates a select series of targets for future studies aimed at identifying genes in ovarian cancer.

Our findings in epithelial ovarian tumors are consistent with similar studies in breast cancer (21 , 22) . In particular, the study of Tirkkonen et al. (21) , which describes metaphase CGH analysis of 21 BRCA1, 12 BRCA2, and 55 sporadic breast tumors, identified 17 significant (P < 0.05) differences in the frequencies of loss or gain between the three groups. As with this study, loss of the BRCA2 region was more frequent in BRCA2 tumors than in BRCA1 and especially sporadic tumors. However, in contrast to our findings, Tirkkonen et al. (21) identified no losses of the BRCA1 region on chromosome 17q but did detect frequent gain on this chromosome arm.

The findings of a previous, similar study in epithelial ovarian cancer (23) are in contrast to those of this study. Trapper et al. (23) analyzed 16 BRCA1, 4 BRCA2, and 20 sporadic ovarian tumors and found only one alteration, a gain on chromosome 2q24-q32, to be more frequent in BRCA1 tumors compared with non-BRCA1 tumors. Our study also identified a higher frequency of gain at 2q24-q32 in BRCA1 tumors compared with other tumor groups, although this did not reach statistical significance. One explanation for the dissimilarity in findings between the two studies could be that the limited statistical power resulting from the smaller number of tumors analyzed by Trapper et al. (23) precluded the identification of additional significant differences.

Moderate or highly penetrant ovarian cancer susceptibility genes, besides BRCA1 and BRCA2, that are responsible for familial clustering of ovarian cancer cases may exist. In the past, CGH analysis has been successfully used for the localization and subsequent identification of a gene associated with the cancer susceptibility syndrome Peutz-Jeghers (24) . More recently, CGH was used to identify a putative breast cancer susceptibility locus on chromosome 13q21-22 in a subset of predominantly Scandinavian non-BRCA1/2-associated breast cancer families (25) , although subsequent studies suggest that if a susceptibility gene does exist at this locus, it is unlikely to be responsible for a substantial proportion of breast cancer families (26) . We have used metaphase CGH to identify somatic genetic alterations in ovarian tumors from families in which no BRCA1 or BRCA2 mutation could be identified. Somatic genetic alterations that are frequent and/or specific to this group of tumors may represent the location of genes associated with inherited susceptibility to ovarian cancer. However, a degree of insensitivity in detecting BRCA1/2 mutations and the possible existence of several rare high to moderate and/or low penetrant ovarian cancer susceptibility genes (genetic heterogeneity) in non-BRCA1/2 families mean that we are unable to suggest with confidence specific candidate susceptibility loci using the current data alone.

Some studies indicate that there are differences in the clinical and/or histopathological characteristics of breast and ovarian tumors between tumors from BRCA1, BRCA2, and non-BRCA1/2 mutation carriers (7, 8, 9, 10, 11, 12, 13) . The reasons for this variation are unknown; BRCA1 and BRCA2 may have a direct effect on the behavior of breast and ovarian epithelial cells, which could vary depending on germ-line BRCA1/2 mutation status. Alternatively, BRCA1/2 mutation status might influence subsequent somatic genetic events in tumorigenesis with these events being responsible for the observed variation in tumor phenotype. The somatic genetic differences that we observed between BRCA1, BRCA2, non-BRCA1/2, and sporadic ovarian tumors provides support for the latter of these hypotheses. A more detailed comparison of the histopathological characteristics of ovarian tumors in BRCA1/2 mutation and nonmutation carriers will be required to obtain a better understanding of this association.

In conclusion, we have used metaphase CGH to characterize the spectrum of somatic genetic events that occur in the development of epithelial ovarian cancer in tumors from BRCA1 and BRCA2 mutation carriers, familial non-BRCA1/2, and sporadic cases. In doing so, we have identified molecular genetic differences between these four tumor groups that suggest there are different mechanisms for tumor development, which may influence the phenotype and clinical outcome of ovarian cancers.


   ACKNOWLEDGMENTS
 
The United Kingdom Coordinating Committee on Cancer Research Familial Ovarian Cancer Register is overseen by a steering committee, including the following members: D. Timothy Bishop, William Collins, Douglas F. Easton, Gordon Fraser, Ian T. Jacobs, David Lowe, James Mackay, Bruce A. J. Ponder, John Shepherd, and C. Mike Steel.


   FOOTNOTES
 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1 This research was supported by a program grant from Cancer Research United Kingdom, National Cancer Institute Research Grants R01CA66190 and 16056, and a BRIEF Award from Brunel University. B. A. J. P. is a Glibb Fellow of Cancer Research United Kingdom Back

2 Present address: Department of Pathology, The University of Melbourne, Victoria, Australia. Back

3 To whom requests for reprints should be addressed, at Cancer Research United Kingdom Translational Oncology Laboratory, Barts and the Royal London, Queen Mary School of Medicine and Dentistry, John Vane Science Centre, Charterhouse Square London EC1M 6BQ, United Kingdom. Phone: 44-20-7882-5795; Fax: 44-20-7882-6110; E-mail: S.A.Gayther{at}qmul.ac.uk Back

4 The abbreviations used are: CGH, comparative genomic hybridization; LOH, loss of heterozygosity. Back

Received 6/ 6/02. Accepted 11/13/02.


   REFERENCES
Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Miki Y., Swensen J., Shattuckeidens D., Futreal P. A., Harshman K., Tavtigian S., Liu Q. Y., Cochran C., Bennett L. M., Ding W., Bell R., Rosenthal J., Hussey C., Tran T., Mcclure M., Frye C., Hattier T., Phelps R., Haugenstrano A., Katcher H., Yakumo K., Gholami Z., Shaffer D., Stone S., Bayer S., Wray C., Bogden R., Dayananth P., Ward J., Tonin P., Narod S., Bristow P. K., Norris F. H., Helvering L., Morrison P., Rosteck P., Lai M., Barrett J. C., Lewis C., Neuhausen S., Cannonalbright L., Goldgar D., Wiseman R., Kamb A., Skolnick M. H. A strong candidate for the breast and ovarian-cancer susceptibility gene BRCA1. Science (Wash. DC), 266: 66-71, 1994.[Abstract/Free Full Text]
  2. Wooster R., Bignell G., Lancaster J., Swift S., Seal S., Mangion J., Collins N., Gregory S., Gumbs C., Micklem G., Barfoot R., Hamoudi R., Patel S., Rice C., Biggs P., Hashim Y., Smith A., Connor F., Arason A., Gudmundsson J., Ficenec D., Kelsell D., Ford D., Tonin P., Bishop D. T., Spurr N. K., Ponder B. A. J., Eeles R., Peto J., Devilee P., Cornelisse C., Lynch H., Narod S., Lenoir G., Egilsson V., Barkadottir R. B., Easton D. F., Bentley D. R., Futreal P. A., Ashworth A., Stratton M. R. Identification of the breast-cancer susceptibility gene BRCA2. Nature (Lond.), 378: 789-792, 1995.[Medline]
  3. Gayther S. A., Russell P., Harrington P., Antoniou A. C., Easton D. F., Ponder B. A. J. The contribution of germline BRCA1 and BRCA2 mutations to familial ovarian cancer: no evidence for other ovarian cancer susceptibility genes. Am. J. Hum. Genet., 65: 1021-1029, 1999.[Medline]
  4. Ford D., Easton D. F., Stratton M., Narod S., Goldgar D., Devilee P., Bishop D. T., Weber B., Lenoir G., ChangClaude J., Sobol H., Teare M. D., Struewing J. A., Scherneck S., Peto J., Rebbeck T. R., Tonin P., Neuhausen S. R., Eyfjord J., Lynch H., Ponder B. A. J., Gayther S. A., Birch J. M., Lindblom A., Stoppa-Lyonnet D., Bignon Y., Borg A., Hamann U., Haites N., Scott R. J., Maugard C. M., Vasen H. Genetic heterogeneity and penetrance analysis of the BRCA1 and BRCA2 in breast cancer families. Am. J. Hum. Genet., 62: 3: 676-689, 1998.[Medline]
  5. Smith S. A., Easton D. F., Evans D. G. R., Ponder B. A. J. Allele losses in the region 17q12-21 in familial breast and ovarian-cancer involve the wild-type chromosome. Nat. Genet., 2: 128-131, 1992.[Medline]
  6. Collins N., McManus R., Wooster R., Mangion J., Seal S., Lakhani S. R., Ormiston W., Daly P. A., Ford D., Easton D. F., Stratton M. R. Consistent loss of the wild-type allele in breast cancers from a family linked to the BRCA2 gene on chromosome 13q12-13. Oncogene, 10: 1673-1675, 1995.[Medline]
  7. Marcus J. N., Watson P., Page D. L., Narod S. A., Lenoir G. M., Tonin P., LinderStephenson L., Salerno G., Conway T. A., Lynch H. T. Hereditary breast cancer, pathobiology, prognosis, and BRCA1 and BRCA2 gene linkage. Cancer (Phila.), 77: 697-709, 1996.[Medline]
  8. Breast Cancer Linkage Consortium Pathology of familial breast cancer: differences between breast cancers in carriers of BRCA1 or BRCA2 mutations and sporadic cases. Lancet, 349: 1505-1510, 1997.[Medline]
  9. Johannsson O. T., Idvall I., Anderson C., Borg A., Barkardottir R. B., Egilsson V., Olsson H. Tumour biological features of BRCA1-induced breast and ovarian cancer. Eur. J. Cancer, 33: 362-371, 1997.
  10. Chang J., Fryatt I., Ponder B., Fisher C., Gore M. E. A matched control study of familial epithelial ovarian cancer: patient characteristics, response to chemotherapy and outcome. Ann. Oncol., 6: 80-82, 1995.[Abstract/Free Full Text]
  11. Rubin S. C., Benjamin I., Behbakht K., Takahashi H., Morgan M. A., LiVolsi V. A., Berchuck A., Muto M. G., Garber J. E., Weber B. L., Lynch H. T., Boyd J. Clinical and pathological features of ovarian cancer in women with germ-line mutations of BRCA1. N. Engl. J. Med., 335: 1413-1416, 1996.[Abstract/Free Full Text]
  12. Pharoah P. D. P., Easton D. F., Stockton D. L., Gayther S. A., Ponder B. A. J. Survival in BRCA1 and BRCA2 associated epithelial ovarian cancer. Cancer Res., 59: 868-871, 1999.[Abstract/Free Full Text]
  13. Ramus S. J., Fishman A., Pharoah P. D. P., Yarkoni S., Alturas M., Ponder B. A. J. Ovarian cancer survival in Ashkenazi Jewish patients with BRCA1 and BRCA2 mutations. Eur. J. Surg. Oncol., 27: 278-281, 2001.[Medline]
  14. van’t Veer L. J., Dai H. Y., van de Vijver M. J., He Y. D. D., Hart A. A. M., Mao M., Peterse H. L., van der Kooy K., Marton M. J., Witteveen A. T., Schreiber G. J., Kerkhoven R. M., Roberts C., Linsley P. S., Bernards R., Friend S. H. Gene expression profiling predicts clinical outcome of breast cancer. Nature (Lond.), 415: 530-536, 2002.[Medline]
  15. Piver M. S., Baker T. R., Jishi M. F., Sandecki A. M., Tsukada Y., Natarajan N., Mettlin C. J., Blake C. A. Familial ovarian cancer. A report of 658 families from the Gilda Radner Familial Ovarian Cancer Registry 1981–1991. Cancer (Phila.), 71: 582-588, 1993.[Medline]
  16. Stratton J., Gayther S. A., Russell P., Dearden J., Gore M., Blake P., Easton D., Ponder B. A. J. The contribution of BRCA1 to ovarian cancer in a British population. N. Engl. J. Med., 336: 1125-1130, 1997.[Abstract/Free Full Text]
  17. Eisen M. B., Spellman P. T., Brown P. O., Botstein D. Cluster analysis and display of genome-wide expression patterns. Proc. Natl. Acad. Sci. USA, 95: 14863-14868, 1998.[Abstract/Free Full Text]
  18. Jacobs I., Lancaster J. The molecular genetics of sporadic and familial epithelial ovarian cancer. Int. J. Gynaecol. Cancer, 6: 337-355, 1996.
  19. Kiechle M., Jacobsen A., Schwarz-Boeger U., Hedderich J., Pfisterer J., Arnold N. Comparative genomic hybridization detects genetic imbalances in primary ovarian carcinomas as correlated with grade of differentiation. Cancer (Phila.), 91: 534-540, 2001.[Medline]
  20. Zweemer R. P., Ryan A., Snijders A. M., Hermsen M. A. J. A., Meijer G. A., Beller U., Menko F. H., Jacobs I. J., Baak J. P. A., Verheijen R. H. M., Kenemans P., van Diest P. J. Comparative genomic hybridization of microdissected familial ovarian carcinoma: two deleted regions on chromosome 15q not previously identified in sporadic ovarian carcinoma. Lab. Investig., 81: 1363-1370, 2001.[Medline]
  21. Tirkkonen M., Johannsson O., Agnarsson B. A., Olsson H., Ingvarsson S., Karhu R., Tanner M., Isola J., Barkardottir R. B., Borg A., Kallioniemi O. P. Distinct somatic genetic changes associated with tumour progression in carriers of BRCA1 and BRCA2 germ-line mutations. Cancer Res., 57: 1222-1227, 1997.[Abstract/Free Full Text]
  22. Hedenfalk I., Duggan D., Chen Y. D., Radmacher M., Bittner M., Simon R., Meltzer P., Gusterson B., Esteller M., Kallioniemi O. P., Wilfond B., Borg A., Trent J. Gene-expression profiles in hereditary breast cancer. N. Engl. J. Med., 344: 539-548, 2001.[Abstract/Free Full Text]
  23. Tapper J., Sarantaus L., Vahteristo P., Nevanlinna H., Hemmer S., Seppala M., Knuutila S., Butzow R. Genetic changes in inherited and sporadic ovarian carcinomas by comparative genomic hybridization: extensive similarity except for a difference at chromosome 2q24–q32. Cancer Res., 58: 2715-2719, 1998.[Abstract/Free Full Text]
  24. Hemminki A., Tomlinson I., Markie D., Jarvinen H., Sistonen P., Bjorkqvist A. M., Knuutila S., Salovaara R., Bodmer W., Shibata, de la Chapelle A., Aaltonen L. A. Localization of a susceptibility locus for Peutz-Jeghers syndrome to 19p using comparative genomic hybridization and targeted linkage analysis. Nat. Genet., 15: 87-90, 1997.[Medline]
  25. Kainu T., Juo S. H. H., Desper R., Schaffer A. A., Gillanders E., Rozenblum E., Freas-Lutz D., Weaver D., Stephan D., Bailey-Wilson J., Kallioniemi O. P., Tirkkonen M., Syrjakoski K., Kuukasjarvi T., Koivisto P. R., Holli K., Arason A., Johannesdottir G., Bergthorsson J. T., Johannsdottir H., Egilsson V., Barkardottir R. B., Johannsson O., Haraldsson K., Sandberg T., Holmberg E., Gronberg H., Olsson H., Borg A., Vehmanen P., Eerola H., Heikkila P., Pyrhonen S., Nevanlinna H. Somatic deletions in hereditary breast cancers implicate 13q21 as a putative novel breast cancer susceptibility locus. Proc. Natl. Acad. Sci. USA, 97: 9603-9608, 2000.[Abstract/Free Full Text]
  26. Thompson D., Szabo C. I., Mangion J., Oldenburg R. A., Odefrey F., Seal S., Barfoot R., Kroeze-Jansema K., Teare D., Rahman N., Renard H., Mann G., Hopper J. L., Buys S. S., Andrulis I. L., Senie R., Daly M. B., West D., Ostrander E. A., Offit K., Peretz T., Osorio A., Benitez J., Nathanson K. L., Sinilnikova O. M., Olah E., Bignon Y. J., Ruiz P., Badzioch M. D., Vasen H. F. A., Futreal A. P., Phelan C. M., Narod S. A., Lynch H. T., Ponder B. A. J., Eeles R. A., Meijers-Heijboer H., Stoppa-Lyonnet D., Couch F. J., Eccles D. M., Evans D. G., Chang-Claude J., Lenoir G., Weber B. L., Devilee P., Easton D. F., Goldgar D. E., Stratton M. R. Evaluation of linkage of breast cancer to the putative BRCA3 locus on chromosome 13q21 in 128 multiple case families from the Breast Cancer Linkage Consortium. Proc Natl Acad Sci USA, 99: 827-831, 2002.[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 Hum Mol GenetHome page
L. Quaye, D. Dafou, S. J. Ramus, H. Song, A. G. Maharaj, M. Notaridou, E. Hogdall, S. K. Kjaer, L. Christensen, C. Hogdall, et al.
Functional complementation studies identify candidate genes and common genetic variants associated with ovarian cancer survival
Hum. Mol. Genet., May 15, 2009; 18(10): 1869 - 1878.
[Abstract] [Full Text] [PDF]

Home page
 Clin. Cancer Res.Home page
S. J. Ramus, K. Elmasry, Z. Luo, A. Gammerman, K. Lu, A. Ayhan, N. Singh, W. G. McCluggage, I. J. Jacobs, J. C. Whittaker, et al.
Predicting Clinical Outcome in Patients Diagnosed with Synchronous Ovarian and Endometrial Cancer
Clin. Cancer Res., September 15, 2008; 14(18): 5840 - 5848.
[Abstract] [Full Text] [PDF]

Home page
 Cancer Res.Home page
E. H. van Beers, T. van Welsem, L. F.A. Wessels, Y. Li, R. A. Oldenburg, P. Devilee, C. J. Cornelisse, S. Verhoef, F. B.L. Hogervorst, L. J. van't Veer, et al.
Comparative Genomic Hybridization Profiles in Human BRCA1 and BRCA2 Breast Tumors Highlight Differential Sets of Genomic Aberrations
Cancer Res., February 1, 2005; 65(3): 822 - 827.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ramus, S. J.
Right arrow Articles by Gayther, S. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ramus, S. J.
Right arrow Articles by Gayther, S. A.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Cancer Research Clinical Cancer Research
Cancer Epidemiology Biomarkers & Prevention Molecular Cancer Therapeutics
Molecular Cancer Research Cancer Prevention Research
Cancer Prevention Journals Portal Cancer Reviews Online
Annual Meeting Education Book Meeting Abstracts Online