Identification of novel variant, 1484delG in the 3'UTR of H3F3B, a member of the histone 3B replacement family, in ovarian tumors

Previous studies have implicated the chromosomal region at 17q25 as harboring tumor suppressor genes based on the frequent loss of heterozygosity (LOH) observed in epithelial ovarian cancers (EOC). RT-PCR validation of Affymetrix GeneChip expression of H3F3B, a member of the 3B histone family that maps to 17q25.1, revealed a doublet band in cDNA from one of four EOC cell lines, OV90. In contrast to three other EOC cell lines (TOV81D, TOV112D and TOV21G) and primary cultures derived from normal ovarian surface epithelial cells (NOSE), sequence analysis of the cDNA revealed a deletion of G at position 1484 of the transcribed sequence which is located within the 3'UTR of H3F3B. OV90 was derived from ascites fluid of an undifferentiated adenocarcinoma of ovarian origin. The variant allele was identified in 1 of 65 (2%) healthy women with no prior history of cancer and in 5 participants with ovarian tumors comprising of 4 of 79 (5%) malignant EOC, none of 10 low malignancy potential tumors, and 1 of 8 (13%) benign tumors. All carriers of the variant alleles were heterozygous and tumor samples did not exhibit preferential LOH of the normal allele. The variant allele was identified in EOC samples of clear cell (1 of 20), mucinous (1 of 8), mixed cell (1 of 3) and undifferentiated (1 of 2) histopathological subtypes but none of 34 serous or 12 endometrioid subtype tumors. One of 3 mucinous benign tumors also harbored the variant allele. The functional significance of the variant is unknown, however its presence in rare subtypes of ovarian epithelial tumors warrants further investigation.

Loss of heterozygosity and transcriptome analyses of a 1.2 Mb candidate ovarian cancer tumor suppressor locus region at 17q25.1-q25.2

Loss of heterozygosity (LOH) analysis was performed in epithelial ovarian cancers (EOC) to further characterize a previously identified candidate tumor suppressor gene (TSG) region encompassing D17S801 at chromosomal region 17q25.1. LOH of at least one informative marker was observed for 100 (71%) of 140 malignant EOC samples in an analysis of 6 polymorphic markers (cen-D17S1839-D17S785-D17S1817-D17S801-D17S751-D17S722-tel). The combined LOH analysis revealed a 453 kilobase (Kb) minimal region of deletion (MRD) bounded by D17S1817 and D17S751. Human and mouse genome assemblies were used to resolve marker inconsistencies in the D17S1839-D17S722 interval and identify candidates. The region contains 32 known and strongly predicted genes, 9 of which overlap the MRD. The reference genomic sequences share nearly identical gene structures and the organization of the region is highly collinear. Although, the region does not show any large internal duplications, a 1.5 Kb inverted duplicated sequence of 87% nucleotide identity was observed in a 13 Kb region surrounding D17S801. Transcriptome analysis by Affymetrix GeneChip and reverse transcription (RT)-polymerase chain reaction (PCR) methods of 3 well characterized EOC cell lines and primary cultures of normal ovarian surface epithelial (NOSE) cells was performed with 32 candidates spanning D17S1839-D17S722 interval. RT-PCR analysis of 8 known or strongly predicted genes residing in the MRD in 10 EOC samples, that exhibited LOH of the MRD, identified FLJ22341 as a strong candidate TSG. The proximal repeat sequence of D17S801 occurs 8 Kb upstream of the putative promoter region of FLJ22341. RT-PCR analysis of the EOC samples and cell lines identified DKFZP434P0316 that maps proximal to the MRD, as a candidate. While Affymetrix technology was useful for initially eliminating less promising candidates, subsequent RT-PCR analysis of well-characterized EOC samples was essential to prioritize TSG candidates for further study.

Gene expression microarray analysis and genome databases facilitate the characterization of a chromosome 22 derived homogeneously staining region

Karyotype and fluorescence in situ hybridization (FISH) analyses previously identified a homogeneously staining region (HSR) derived from chromosome 22 in OV90, an epithelial ovarian cancer (EOC) cell line. Affymetrix expression microarrays in combination with the UniGene and Human Genome Browser databases were used to identify the candidate genes comprising the amplicon of the HSR, based on comparison of expression profiles of OV90, EOC cell lines lacking HSRs and primary cultures of normal ovarian surface epithelial (NOSE) cells. A group of probe sets displaying a minimum 3-fold overexpression with a high reliability score (P-call) in OV90 were identified which represented genes that mapped within a 1-2 Mb interval on chromosome 22. A large number of probe sets, some of which represent the same genes, displayed no evidence of overexpression and/or low reliability scores (A-call). An investigation of the probe set sequences with the Affymetrix and Sanger Institute Chromosome 22 Group databases revealed that some of the probe sets displaying discordant results for the same gene were complementary to intronic sequences and/or the antisense strand. Microarray results were validated by RT-PCR. Genomic analysis suggests that the HSR was derived from the amplification of a 1.1 Mb interval defined by the chromosomal map positions of ZNF74 and Hs.372662, at 22q11.21. The deduced amplicon is derived from a complex region of chromosome 22 that harbors low-copy repeats (LCRs). The amplicon contains 18 genes as likely targets for gene amplification. This study illustrates that large-scale expression microarray analysis in combination with genome databases is sufficient for deducing target genes associated with amplicons and stresses the importance of investigating probe set design before engaging in validation studies.

Signature of a silent killer: expression profiling in epithelial ovarian cancer

With the sequencing of the human genome and the simultaneous development of high-throughput strategies, cancer biologists have entered an exciting new area for gene expression analysis, with the ability to glimpse higher order patterns of genetic and epigenetic alterations in complex diseases. Ovarian cancer biologists are rising to the challenge of applying these new technologies to this silent killer, with the eventual goal of improving the quality of life and long-term survival of patients. This review provides a summary of the disease, a description of available technologies and their application to the ovarian cancer problem, as well as a discussion on the challenges and opportunities related to DNA microarray expression profiling-based research, including downstream clinical applications.

Signature of a silent killer: expression profiling in epithelial ovarian cancer

With the sequencing of the human genome and the simultaneous development of high-throughput strategies, cancer biologists have entered an exciting new area for gene expression analysis, with the ability to glimpse higher order patterns of genetic and epigenetic alterations in complex diseases. Ovarian cancer biologists are rising to the challenge of applying these new technologies to this silent killer, with the eventual goal of improving the quality of life and long-term survival of patients. This review provides a summary of the disease, a description of available technologies and their application to the ovarian cancer problem, as well as a discussion on the challenges and opportunities related to DNA microarray expression profiling-based research, including downstream clinical applications.

The Effect of Music on the Neurohormonal Stress Response to Surgery Under General Anesthesia

Several pharmacological interventions reduce perioperative stress hormone release during surgery under general anesthesia. Listening to music and therapeutic suggestions were also studied, but mostly in awake patients, and these have a positive effect on postoperative recovery and the need for analgesia. In this study, we evaluated the effect of listening to music under general anesthesia on the neurohormonal response to surgical stress as measured by epinephrine, norepinephrine, cortisol, and adrenocorticotropic hormone (ACTH) blood levels. Thirty female patients scheduled for abdominal gynecological procedures were enrolled and randomly divided into two groups: group NM (no music) and group M (music). In group M, music was played from after the induction of anesthesia until the end of surgery. In the NM group, the patients wore the headphones but no music was played. We established three sample times for hormonal dosage during the procedure and one in the recovery room. Hemodynamic data were recorded at all times, and postoperative consumption of morphine in the first 24 h was noted. There was no group difference at any sample time or in the postoperative period in terms of mean arterial blood pressure, heart rate, isoflurane end-tidal concentration, time of the day at which the surgery was performed, bispectral index (BIS) value, doses of fentanyl, or consumption of postoperative morphine. There was no difference between the two groups with regard to plasmatic levels of norepinephrine, epinephrine, cortisol, or ACTH at any sample time, although the blood level of these hormones significantly increased in each group with surgical stimulation. In conclusion, we could not demonstrate a significant effect of intraoperative music on surgical stress when used under general anesthesia.

IMPLICATIONS

Listening to music under general anesthesia did not reduce perioperative stress hormone release or opioid consumption in patients undergoing gynecological surgery.

Significant proportion of breast and/or ovarian cancer families of French Canadian descent harbor 1 of 5BRCA1 andBRCA2 mutations

In 1998, we reported that a significant proportion of breast and/or ovarian cancer families of French Canadian descent harbor specific germline mutations in BRCA1 or BRCA2 attributed to common founders. Here we report the frequency of previously described mutations (n = 7) and 13 mutations identified in French Canadian families since 1998, in a new group of families (n = 88). Four of the previously described mutations, 4446C>T, 2953delGTAinsC, 8765delAG and 6085C>T, account for 72% and 69% of mutation-positive families in previously (n = 81) and recently ascertained groups, respectively. Only 2 of 13 recently identified mutations were found in more than 1 family: 3875delGTCT (n = 2) and 3398delAAAAG (n = 4). The 2 groups (ascertained pre- and post-gene discovery) did not differ significantly when distribution of mutations based on cancer syndrome phenotype and age of diagnosis or number of breast cancer cases were compared. Five common mutations accounted for a significant proportion (84%) of all mutation-positive families. The age of diagnosis of female breast cancer in mutation-negative families was significantly higher than that of the mutation-positive families (p<0.0001). The total number of cases of cancer per family was significantly lower in mutation-negative than mutation-positive families (p<0.001). Our results define a new mutation panel for screening BRCA1/2 mutations and the phenotype of mutation-positive families harboring the common mutations in the French Canadian population.

Use of hormonal replacement therapy after treatment of breast cancer

OBJECTIVE

To review the use of hormonal replacement therapy (HRT) after treatment of breast cancer.

OPTIONS

The effect and role of estrogens on breast cancer.

OUTCOME

Improved health and quality of life for women with breast cancer.

VALUES

References were collected through MEDLINE searches up to 2002.

EVIDENCE

The level of evidence and quality of recommendations have been determined using the criteria described by the Canadian Task Force on the Periodic Health Examination.

BENEFITS, HARMS, AND COSTS

Utilization of the information to make a proper risk-benefit assessment of HRT use in women with breast cancer.

RECOMMENDATIONS

1. HRT after treatment of breast cancer has not been demonstrated to have an adverse impact on recurrence and mortality.(II-2B) 2. HRT is an option in postmenopausal women with previously treated breast cancer.(II-2B) 3. Prospective, randomized clinical trial results are needed.(III-A) VALIDATION: Recommendations were reviewed and revised by the Breast Disease Committee of the Society of Obstetricians and Gynaecologists of Canada (SOGC) and approved by the Executive and Council of the SOGC.

SPONSOR

The Society of Obstetricians and Gynaecologists of Canada.

Patterns of expression of chromosome 17 genes in primary cultures of normal ovarian surface epithelia and epithelial ovarian cancer cell lines

Oligonucleotide microarray analysis was applied to assess the expression profile of 332 probe sets representing 308 genes or expressed sequence tags (ESTs) that map to chromosome 17 in order to address epigenetic events that result in alterations in gene expression in epithelial ovarian cancer (EOC). Expression profiles were generated from 12 primary cultures derived from normal ovarian surface epithelium (NOSE) and four long-term cultures (TOV-81D, TOV-112D, TOV-21G and OV-90) derived from EOCs that have been previously characterized and shown to mimic features of the tumoral cells from which they were derived. The expression values of all 332 probe sets is highly correlated across the 12 NOSEs (89% correlation coefficients >0.90). In two-way comparisons, differential patterns of gene expression were observed for 157 probe sets for which the expression value of at least one EOC cell line fell outside the limits of the range of expression of the 12 NOSEs. When compared to NOSEs, four genes displayed similar differential patterns of gene expression across all four EOC cell lines, and 26 genes displayed similar differential patterns of gene expression across the three EOC cell lines (TOV-112D, TOV-21G and OV-90) representing tumoral cells derived from the most aggressive disease. A total of 17 genes displayed differential patterns of gene expression greater than threefold in at least one EOC cell line in comparison to NOSE, and three genes were differentially expressed greater than threefold across all aggressive cell lines. The analysis of a selected number of genes by RT-PCR revealed patterns of gene expression comparable to those observed by microarray analysis in the majority of samples tested. Comparison of expression profiles of differentially expressed genes identified by microarray analysis in two-way comparisons of the EOC cell lines and the NOSEs with published reports revealed 10 genes previously implicated in ovarian tumorigenesis and 18 in tumorigenesis of other types of cancer. The differential pattern of gene expression of genes that map to both the p and q arm of chromosome 17 is consistent with the hypothesis that a number of genes that map to this chromosome are implicated in the etiology of ovarian cancer.

Herpes simplex virus type II is not a cofactor to human papillomavirus in cancer of the uterine cervix

OBJECTIVE

Cells that were cotransfected with herpes simplex virus-16 and the herpes simplex virus type 2 Xho -2 DNA induce tumors in nude mice. In a cross-sectional study, we investigated the role of herpes simplex virus type 2 as a cofactor to human papillomavirus in cervical cancer.

STUDY DESIGN

Cervical cells that were obtained with an endocervical Cytobrush brush (Medscand) from 439 women (50 women with cancer lesions, 65 women with high-grade squamous intraepithelial lesions, 80 women with low-grade squamous intraepithelial lesions, 244 healthy subjects) and DNA that was extracted from 150 cervical cancer biopsy specimens were analyzed with polymerase chain reaction for herpes simplex virus type 2 Xho -2 and Bgl IIC transforming DNA sequences.

RESULTS

All 439 cervical samples and 150 cervical cancer biopsy specimens tested negative for herpes simplex virus type 2 Xho -2 and Bgl IIC DNA by polymerase chain reaction. Overall, none of 200 samples (0%) from women with invasive cervical cancer contained herpes simplex virus type 2 Xho -2 or Bgl IIC DNA (95% CI, 0.0-1.8).

CONCLUSION

Although herpes simplex virus type 2 Bgl IIN transforms epithelial cells in vitro, it was not detected in cervical cancer specimens.

Oral contraceptives and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

BACKGROUND

Oral contraceptive use has been associated with an increase in the risk of breast cancer in young women. We examined whether this association is seen in women at high risk of breast cancer because they carry a mutation in one of two breast cancer susceptibility genes, BRCA1 and BRCA2.

METHODS

We performed a matched case-control study on 1311 pairs of women with known deleterious BRCA1 and/or BRCA2 mutations recruited from 52 centers in 11 countries. Women who had been diagnosed with breast cancer were matched to control subjects by year of birth, country of residence, mutation (BRCA1 or BRCA2), and history of ovarian cancer. All study subjects completed a questionnaire about oral contraceptive use. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived by conditional logistic regression. All statistical tests were two-sided.

RESULTS

Among BRCA2 mutation carriers, ever use of oral contraceptives was not associated with an increased risk of breast cancer (OR = 0.94, 95% CI = 0.72 to 1.24). For BRCA1 mutation carriers, ever use of oral contraceptives was associated with a modestly increased risk of breast cancer (OR = 1.20, 95% CI = 1.02 to 1.40). However, compared with BRCA1 mutation carriers who never used oral contraceptives, those who used oral contraceptives for at least 5 years had an increased risk of breast cancer (OR = 1.33, 95% CI = 1.11 to 1.60), as did those who used oral contraceptives before age 30 (OR = 1.29, 95% CI = 1.09 to 1.52), those who were diagnosed with breast cancer before age 40 (OR = 1.38, 95% CI = 1.11 to 1.72), and those who first used oral contraceptives before 1975 (OR = 1.42, 95% CI = 1.17 to 1.75).

CONCLUSIONS

Among BRCA1 mutation carriers, women who first used oral contraceptives before 1975, who used them before age 30, or who used them for 5 or more years may have an increased risk of early-onset breast cancer. Oral contraceptives do not appear to be associated with risk of breast cancer in BRCA2 carriers, but data for BRCA2 carriers are limited.

Detection of human herpes virus type 6 DNA in precancerous lesions of the uterine cervix

Human herpes virus type 6 (HHV-6) DNA has been suggested to be a cofactor to human papillomavirus (HPV) in cervical cancer. In a cross-sectional study, we investigated the association between HHV-6 DNA detected in cervical brushings and high-grade squamous intraepithelial lesions (HSIL), while controlling for genital infection with 27 genotypes of HPV. Of the 320 women recruited from an oncologic gynecology clinic, 50 had invasive cervical cancer, 65 had HSIL, 80 had low-grade squamous intraepithelial lesions (LSIL), and 125 were normal. Four of the seven HHV-6-positive women had HSIL. HHV-6 was associated with HSIL after adjusting for age and socioeconomic status (odds ratio [OR] of 10.9, 95% confidence interval [CI]: 1.1-107.1). This association was no longer significant after controlling for HPV (OR = 6.4, 95% CI = 0.3-128.5). HHV-6 was detected in cervical samples from women with precancerous and cancerous lesions of the cervix, but not significantly more frequently than in normal women.

Comparative analysis of loss of heterozygosity of specific chromosome 3, 13, 17, and X loci and TP53 mutations in human epithelial ovarian cancer

We previously reported the identification of three minimal regions of deletion on the short arm of chromosome 3 (3p) in epithelial ovarian tumor specimens, suggesting that the inactivation of tumor-suppressor genes in these regions may be important in terms of ovarian tumorigenesis. Another previous study of ovarian cancer observed that allele loss of chromosome 179 was frequently found in ovarian tumors that also showed loss of heterozygosity (LOH) of chromosomes 3p, 13q, 17p, and Xp. In an independent study, we also reported a high frequency of LOH for selected chromosome 17 loci in high-grade and late-stage ovarian tumors. We have extended our LOH analysis of chromosome 3p to include 102 ovarian tumor specimens (29 and 73 samples were previously examined for LOH of chromosome 3p and 17 markers, respectively), using additional polymorphic markers, to assess the coordinate LOH of loci representing the three chromosome 3p minimal regions of deletions [von Hippel-Lindau syndrome (VHL), thyroid hormone receptor beta, and fragile histidine triad (FHIT)] and LOH of other important loci [tumor protein 53 (TP53), breast cancer 1 early onset (BRCA1), breast cancer 2 early onset, retinoblastoma 1, ornithine carbamoyltransferase, and androgen receptor] or somatic mutations in TP53. There was a significant association between LOH of any chromosome 3p marker and LOH of any chromosome 17 marker (P = 0.026). The frequency of LOH at the TP53 locus was higher in the group of samples that displayed LOH of a 3p marker (P = 0.019), as was the frequency of LOH at the BRCA1 locus (P = 0.014). LOH of chromosome 3p was noted in four specimens that did not display LOH of either the BRCA1 or the TP53 locus, indicating that LOH of these loci need not precede LOH of the chromosome 3p loci. We found a significant association between LOH of the VHL (3p25) locus and LOH of any chromosome 17 marker (P = 0.005), suggesting that there may be an important relationship, in the tumorigenesis of epithelial ovarian cancer, between a gene at 3p25 and a gene located on chromosome 17. Our results indicate that inactivation of p53 by somatic mutation is unlikely to be a prerequisite to chromosome 3p LOH, because we found no significant association between mutations in TP53 and LOH of the three chromosome 3p loci. The frequency of LOH at the FHIT locus at 3p14 increased significantly with advancing age at diagnosis (P = 0.018), as did the frequency of somatic TP53 mutations (P = 0.008).

Breast cancer, pregnancy, and breastfeeding

OBJECTIVE

The primary objective of this guideline is to provide Canadian physicians up-to-date, accurate information and recommendations regarding: i) impact of pregnancy and lactation on risk of breast cancer; ii) prognosis of breast cancer diagnosed during pregnancy and lactation; iii) risk of recurrence of breast cancer with the occurrence of subsequent pregnancies; iv) feasibility of breastfeeding and its impact on the prognosis of women with breast cancer.

OPTIONS

This guideline reviews evidence on whether pregnancy and breastfeeding change the lifetime risk for breast cancer in women, and whether breast cancer diagnosed during pregnancy or during lactation has a different prognosis. It offers the clinician advice on the diagnostic options to help identify breast cancer in pregnancy and/or during lactation, and offers evidence-based recommendations in managing an ongoing pregnancy and/or lactation when treatment for breast cancer is being planned. It also offers recommendations to clinicians in counselling their patients regarding future pregnancy and future breastfeeding for women who have been treated for breast cancer.

OUTCOMES

These guidelines should help physicians counsel patients using evidence-based recommendations. These recommendations may also improve the prognosis of patients diagnosed with breast cancer during pregnancy and lactation, or of those patients who had breast cancer and are contemplating future pregnancies.

EVIDENCE

A Medline search was carried out for all publications from 1990 through 2000, in the English language, related to breast cancer and pregnancy in terms of diagnosis, prognosis, and treatment, as well as for breast cancer and breastfeeding, with particular focus on impact of treatment of breast cancer on lactation and prognosis of breast cancer after lactation. The authors submitted the manuscript for review to members of the Breast Disease Committee, who also validated the levels of evidence. The final manuscript was submitted to the SOGC Council for approval and dissemination. The levels of evidence for recommendations have been determined using the criteria described by the Canadian Task Force on the Periodic Health Examination.

BENEFITS, HARMS, AND COSTS

Canadian physicians will be able to counsel their patients on the impact of pregnancy and lactation on a woman's lifetime risk for breast cancer. Physicians and patients will be empowered to decide how to manage pregnancy and lactation when breast cancer is diagnosed in pregnancy, and to appreciate the ramifications of reproduction and breastfeeding after breast cancer. This guideline identifies areas where good evidence is lacking and advocates research in those areas.

RECOMMENDATIONS

Women should be counselled regarding their risk for breast cancer and be informed that: 1. There is good evidence that there is a transient increase in risk of breast cancer in the first three to four years after delivery of a singleton baby (II-2B). Subsequently, their lifetime risk seems lower than that of women who remain nulliparous (II-2B). 2. There is good evidence that the risk for premenopausal breast cancer is reduced with lactation (II-2A). This protective effect seems to be best for women who had extended periods of breastfeeding during their lifetime (ll-2B). Women with familial risks could potentially benefit most from breastfeeding (II-2C). Since breast milk is the ideal nutrient for the newborn, and since breastfeeding is a modifiable risk factor, all women should be encouraged to breastfeed their children (II-2A). 3. All women should be encouraged to practice breast self-examination in pregnancy and during lactation (II-2B). Clinicians should screen all pregnant patients for breast cancer with thorough breast examination early in pregnancy (III-B). The clinician is advised to examine the breast in the postpartum period if the woman is not breastfeeding. The obstetrician is advised to examine the breast at any time in the postpartum period if the woman presents with breast symptoms (III-B). 4. Physicians should be encouraged to use ultrasltrasonography, mammography, needle aspiration, or breast biopsies to assess suspicious breast masses in pregnancy and during lactation, in the same timely fashion as for non-pregnant or non-lactating women (II-2A). Interruption of lactation during investigation is not necessary, nor is it recommended unless nuclear studies are entertained (III-B). 5. Once breast cancer is diagnosed, a multidisciplinary approach should be taken. This includes the obstetrician, surgeons, medical and radiation oncologists, and breast cancer counsellors (II-2A). 6. In early pregnancy, the patient should be counselled regarding the effect of proposed therapy on the fetus and on overall maternal prognosis. Termination of pregnancy should be discussed, but the patient should be counselled that prognosis is not altered by termination of pregnancy. Women should be advised that premature menopause may result from breast cancer treatments, especially if chemotherapy is given to patients who are past the age of 30. (II-2C) 7. Up until now, modified radical mastectomy was the cornerstone of surgical treatment of breast cancer during pregnancy. Adjuvant chemotherapy should be entertained and, if required, administered without delay. The patient should be counselled regarding the effect of chemotherapy on the fetus and/or the future reproductive potential of the patient (II-2B). In the third trimester, the risks and benefits of early delivery versus continuation of pregnancy, and the effect of chemotherapy on the fetus, should be addressed (II-2B). Women undergoing chemotherapy or tamoxifen treatment should not breastfeed (III-B). 8. Women treated for breast cancer and who wish to become pregnant should be counselled that pregnancy is possible and does not seem to be associated with a worse prognosis for their breast cancer (II-3C). However, they should be made aware that the evidence to support such advice is relatively poor. 9. Since most breast cancer recurrences appear within two to three years after initial diagnosis, patients should be advised to postpone pregnancy for three years (III-C). If a patient has axillary node involvement, the recommendation to defer pregnancy should be extended to five years, but this recommendation is based on opinion only (III-C). Prior to attempting pregnancy, a breast cancer survivor should be referred for a full oncologic evaluation. 10. There is no evidence that breastfeeding increases the risk of breast cancer recurring or of a second breast cancer developing, nor that it carries any health risk to the child. Women previously treated for breast cancer, who do not show any evidence of residual tumour, should be encouraged to breastfeed their children (III-B).

VALIDATION

Level of evidence, quality of research in the recruited publications, and ensuing recommendations were reviewed and discussed by members of the SOGC Breast Disease Committee as well as by a member of the Gynaecological Oncology Committee. External reviewers with expertise in the area were also solicited for comments and criticism.

Expression profiles of 290 ESTs mapped to chromosome 3 in human epithelial ovarian cancer cell lines using DNA expression oligonucleotide microarrays

We have investigated previously the utility of oligonucleotide expression microarray technology in an analysis of four spontaneously transformed epithelial ovarian cancer (EOC) cell lines, TOV-21G, TOV-81D, OV-90, and TOV-112D. Here, we examine the expression of 290 expressed sequence tags (ESTs) that map to human chromosome 3 in a primary culture derived from normal ovarian surface epithelium (NOSE), NOV-31, and the four spontaneously transformed EOC cell lines. One of these cell lines, OV-90, harbors a deletion of an entire chromosome 3p arm. Whereas the most aggressive cell lines (OV-90, TOV-112D, and TOV-21G) exhibited the highest levels of expression, assessed by the mean of expression values of all ESTs, OV-90 showed the lowest mean of expression of ESTs that map to the 3p arm in comparison with TOV-112D and TOV-21G. This difference in expression profile of 3p ESTs in OV-90 is also reflected in the ratio of expression of ESTs on 3p versus the 3q arm and in that the expression values of ESTs that map to 3p were more often lower than higher in OV-90 in two-way comparisons with NOV-31, TOV-21G, and TOV-112D. The loss of a 3p arm does not affect the pattern of differential expression in analyses based on the range of numeric expression values of each EST or fold differences in expression for each EST in comparison with NOV-31. However, 25 differentially expressed ESTs were identified on the basis of threefold differences in expression values between NOV-31 and any EOC cell line; and six of these ESTs were differentially expressed uniquely in OV-90. The investigation of these ESTs could facilitate the identification of novel chromosome 3 genes implicated in ovarian tumorigenesis.

Microarray analysis of gene expression mirrors the biology of an ovarian cancer model

We have previously described an ovarian cancer model based on four independent spontaneously immortalized epithelial ovarian cancer cell lines (TOV-21G, TOV-81D, TOV-112D and OV-90) from patients who were never exposed to chemotherapy or radiation therapy. These cell lines are particularly interesting since they retain characteristics of the original epithelial ovarian cancers (EOC) from which they were derived. Here we report the characterization of this model system using high-density DNA microarrays in order to assess gene expression. Expression profiles were generated from total RNAs extracted from the four EOC cell lines. For comparison, expression profiling is also provided for a primary culture of normal ovarian surface epithelium (NOV-31) and a fresh EOC sample (TOV-578G). Comparison of expression profiles revealed patterns of expression that distinguish NOV-31 from that of all tumor derived samples. The expression pattern of TOV-81D, an EOC cell line that was derived from a patient with indolent disease, most closely resembles NOV-31 while profiles of samples derived from patients with more aggressive disease (TOV-21G, OV-90, TOV-112D and TOV-578G) showed more divergent patterns of expression. The microarray analysis (http://genome.mcgill.ca) results confirm the usefulness of an ovarian cancer model based on the characterization of these EOC cell lines.

Haplotype analysis of BRCA2 8765delAG mutation carriers in French Canadian and Yemenite Jewish hereditary breast cancer families

The BRCA2 8765delAG mutation was previously reported in hereditary breast cancer families of French Canadian and Yemenite Jewish descent. Haplotype analysis, using six microsatellite markers that span BRCA2 and two intragenic polymorphisms, was performed on 8765delAG mutation carriers to determine if there was evidence that the mutations were identical by descent. The alleles of the microsatellite markers most closely flanking BRCA2 (D13S1697 and D13S1701) were found to be identical in state in all the mutation carriers. However, the disease-associated allele of one of the intragenic markers differed between the Yemenite Jews and French Canadian families, indicating that the 8765delAG mutation has independent origins in these two geographically and ethnically distinct populations.

Trisomy of chromosome 10 in two cases of ovarian carcinoma

Simple numerical chromosome aberrations have been observed in tumorigenesis and may point to indicative initiating or early events in tumorigenesis. We have identified two cases of ovarian carcinomas with trisomy of chromosome 10 using conventional GTG-banding and fluorescence in situ hybridization. This is, to our knowledge, the first report of trisomy 10 as a simple karyotypic abnormality observed in ovarian carcinoma. These results suggest that further studies investigating whether chromosome 10 genes are associated with the pathogenesis of some ovarian tumors are warranted.

Allelotyping defines minimal imbalance at chromosomal region 17q25 in non-serous epithelial ovarian cancers

Allelic deletions of multiple chromosome 17q loci in sporadic ovarian cancer of epithelial origin suggest that inactivation of tumor suppressor gene(s) in these regions may be important for ovarian tumorigenesis. To further define the pattern of allelic imbalance in epithelial ovarian tumors of different histologies, a PCR-based assay was used to assess loss of heterozygosity (LOH) of polymorphic markers representative of TP53, BRCA1, NME1 and GH1, and region 17q23-25. LOH was observed for at least one marker in 68% of malignant tumors (n=60) and in 18% tumors of borderline malignancy (n=11), but not in benign tumors (n=5). The highest frequency of LOH in malignant tumors (64%) was observed with D17S801 on 17q25. Ten of 39 malignant ovarian tumors displaying LOH of at least one 17q marker, displayed a LOH pattern enabling the determination of a minimal region of overlapping deletion defined by D17S795 and D17S801. One borderline tumor also displayed an interstitial LOH pattern that overlapped this 17q25 minimal region of deletion. The histologies of malignant tumors displaying a pattern indicative of interstitial 17q deletions were of the endometrioid, clear cell and mucinous epithelial types. As the minimal region of overlap defined by these tumors overlap regions deleted in malignant tumors of all histologic types, and in a tumor of borderline malignancy, the 17q25-tumor suppressor may be implicated in the development of all types of epithelial ovarian tumors.

Founder BRCA1 and BRCA2 mutations in French Canadian ovarian cancer cases unselected for family history

The breast cancer susceptibility genes, BRCA1 and BRCA2, differ in their contribution to ovarian cancer. Recently, founder mutations in each of these genes were identified in Canadian breast cancer and breast ovarian cancer families of French ancestry. We have examined the prevalence of the founder mutations in a series of 113 French Canadian women with ovarian cancer unselected for family history. Germline mutations were found in eight of 99 invasive carcinomas and in none of the 14 tumors of borderline malignancy. Five cases carried the BRCA1 C4446T mutation and two cases carried the BRCA2 8765delAG mutation which are the most common mutations that have been described in French Canadian breast cancer and breast ovarian cancer families. All of these cases reported a family history of at least one first-degree relative with breast cancer, diagnosed below age 60 years, or with ovarian cancer. The identification of founder BRCA1 and BRCA2 mutations in ovarian cancer cases unselected for family history can facilitate carrier detection when the expected yield of a comprehensive screen may be low.

Mapping of chromosome 3p deletions in human epithelial ovarian tumors

Epithelial ovarian tumors frequently display deletions on the short arm of chromosome 3 suggesting the existence of tumor suppressor genes within the deleted regions. We have recently established a primary tissue culture system as a model to investigate the genetic events associated with ovarian cancer. The frequencies of loss of heterozygosity (LOH) at 16 loci representative of chromosome 3p in 33 tumor biopsies and 47 ovarian primary cultures derived from unselected ovarian cancers were examined. This repertoire also included benign and borderline tumors as well as malignant ovarian ascites. LOH was observed in 25 (31%) samples for at least one marker: 21 of 58 malignant, two of 12 borderline and two of 10 benign specimens. Chromosome 3p loss was not restricted to ovarian tumors of high grade and stage. LOH was observed in both cultured and non cultured tumors and ascites. A spontaneously immortalized cell line derived from a malignant ovarian ascites, OV-90, displayed LOH of the majority of markers suggesting loss of one homolog of chromosome 3p. The pattern of deletion displayed by these 25 samples enabled the determination of at least two distinct regions of overlapping deletions on chromosome 3p extending from D3S1270 to D3S1597 and from D3S1293 to D3S1283. In addition, a region proximal to D3S1300 was deleted in a subset of samples. Although loss of loci overlapping these three regions (Regions I, II and III) were observed in malignant and benign tumors, in borderline tumors loss was observed of markers representative of Region III only. While RARbeta is presently included in Region II, the minimal regions of deletion exclude VHL, TGFBR2, PTPase(gamma) and FHIT as candidate tumor suppressors in ovarian tumorigenesis.