C-terminal binding protein-2 regulates response of epithelial ovarian cancer cells to histone deacetylase inhibitors.

Ovarian cancer survival rates have stagnated in the last 20 years despite the development of novel chemotherapeutic agents. Modulators of gene expression, such as histone deacetylase (HDAC) inhibitors, are among the new agents being used in clinical trials. Predictors of sensitivity to chemotherapy have remained elusive. In this study, we show that the expression of the transcriptional corepressor C-terminal binding protein-2 (CtBP2) is elevated in human ovarian tumors. Downregulation of CtBP2 expression in ovarian cancer cell lines using short-hairpin RNA strategy suppressed the growth rate and migration of the resultant cancer cells. The knockdown cell lines also showed upregulation of HDAC activity and increased sensitivity to selected HDAC inhibitors. Conversely, forced expression of wild-type CtBP2 in the knockdown cell lines reversed HDAC activity and partially rescued cellular sensitivity to the HDAC inhibitors. We propose that CtBP2 is an ovarian cancer oncogene that regulates gene expression program by modulating HDAC activity. CtBP2 expression may be a surrogate indicator of cellular sensitivity to HDAC inhibitors.

Effect of a c-Met-specific, ATP-competitive small-molecule inhibitor SU11274 on human ovarian carcinoma cell growth, motility, and invasion.

Increased expression of the receptor tyrosine kinase c-Met has been shown to correlate with enhanced cell proliferation, motility, and invasion. The objectives of this study were to characterize total and activated c-Met expression in both normal and malignant human ovarian epithelial cells and to determine the effects of inhibiting the activation of c-Met on ovarian epithelial cell growth, motility, and invasion. Total c-Met was overexpressed in 82 (68%) of 119 ovarian carcinomas, as shown by immunohistochemistry. Quantitative reverse transcription-polymerase chain reaction and Western blot analyses revealed that ovarian carcinoma cell lines had higher levels of c-Met messenger RNA, total protein, and activated protein expression compared to normal ovarian epithelial cell cultures. Using a specific adenosine triphosphate-competitive small-molecule inhibitor, SU11274, activated c-Met was decreased in normal and ovarian carcinoma cell lines. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays showed that cell growth inhibition directly correlated to the level of activated c-Met detected in each cell line (r =-0.87, P = 0.012). Using modified Boyden chamber assays, ovarian carcinoma cells treated with SU11274 demonstrated significantly decreased cell motility and invasion compared to untreated cells (P = 0.003 and P < 0.001, respectively). These data indicate that c-Met is overexpressed in the majority of malignant ovarian epithelial cells both in vivo and in vitro and that decreasing activated c-Met in vitro can significantly decrease ovarian carcinoma cell growth, motility, and invasion. Developing therapies that specifically inhibit the activation of c-Met may represent a novel therapeutic modality for patients with ovarian carcinomas expressing high levels of c-Met.

Large calcifications in ovaries otherwise normal on ultrasound.

OBJECTIVE: To evaluate calcifications >or= 5 mm in length in ovaries that are otherwise normal on ultrasound, and to determine whether such large ovarian calcifications are an indicator of ovarian neoplasm. METHODS: This was a retrospective study reviewing pelvic ultrasound results at our unit between October 1994 and April 2002 to identify patients with ovarian calcifications that were >or= 5 mm in maximum length in otherwise normal ovaries, and who also had follow-up imaging studies. Patient medical histories were reviewed, calcification characteristics, including number, size, shape and laterality of calcifications, were recorded and follow-up imaging studies were reviewed to assess change in size of the calcification and to see if a neoplasm had developed. RESULTS: The study group consisted of 28 patients. The mean length of imaging follow-up was 35.2 +/- 30.7 months. The mean size of the calcifications was 7.4 +/- 2.3 (range, 5-13) mm. The calcification remained stable in all 28 patients and no ovarian neoplasms developed in any of the patients. Histological confirmation was available in one patient and this revealed dystrophic calcification in a corpus albicans. CONCLUSION: Calcifications ranging from 5 to 13 mm in length in otherwise normal ovaries remain stable on follow-up imaging and are not an indicator of current or future ovarian neoplasm. Published by John Wiley & Sons, Ltd.

Distinct allelic loss patterns in papillary serous carcinoma of the peritoneum.

Tumor and normal tissues from 55 patients with papillary serous carcinoma of the peritoneum (PSCP) were analyzed. Polymerase chain reaction amplification of tandem repeat polymorphism was used to screen for loss of heterozygosity (LOH). We mapped 22 oligonucleotide primers to chromosomes 1p, 3p, 6q, 7q, 9p, 11p, 17p, 17q, and Xq. Germline BRCA1 mutation status of 43 patients was determined previously. High frequencies (> 30%) of LOH in PSCP were observed on 6q, 9p, 17p, 17q, and Xq. Compared with allelic loss of serous epithelial ovarian carcinoma (SEOC), the frequency of LOH was significantly lower in PSCP on 1p, 7q, 11p, 17p, and 17q. Of 43 cases screened for germline BRCA1 mutations, 9 cases were identified with mutations. The frequencies of LOH were not significantly different among the BRCA1-related and BRCA1-unrelated PSCP cases. The high LOH rate identified on 6q, 9p, 17p, 17q, and Xq in PSCP suggests that candidate tumor suppressor genes residing in these regions may be important for the development of the tumor. Compared with allelic loss of SEOC, PSCP exhibits a significantly lower frequency of LOH on chromosomes 1p36, 7q31.3, 11p15.1, 17p13.1, and 17q21. An increase in susceptibility to the acquisition of allelic loss in BRCA1-related PSCP cannot be identified.

Occult ovarian tumors in women with BRCA1 or BRCA2 mutations undergoing prophylactic oophorectomy.

PURPOSE: To review the findings at prophylactic oophorectomy of a series of women who presented to a familial breast and ovarian cancer clinic. MATERIALS AND METHODS: Data from medical charts, operative notes, and pathology reports were collected on women who had undergone prophylactic oophorectomies because of the elevated risk of ovarian cancer. Because only a subset of patients underwent BRCA1 and BRCA2 testing, each patient's risk of hereditary predisposition was calculated using the Berry-Parmigiani model and family history data. RESULTS: From June 1989 to December 1998, 50 women seen at our clinic underwent prophylactic oophorectomy, 33 of whom had a calculated risk of carrying a germline BRCA1 or BRCA2 mutation greater than 25%. Among this group, four incidental tumors were found (four of 33, or 12%); one tumor was noted at the time of surgery and three were noted only in the final pathology. Two patients had microscopic, poorly differentiated serous adenocarcinomas in multiple sites on both ovaries. A third patient had a bilateral serous borderline tumor with micropapillary features. The fourth patient had a microscopic serous borderline ovarian tumor. All four patients had germline BRCA1 or BRCA2 mutations, and three had unremarkable transvaginal ultrasonography examinations within 6 months before prophylactic surgery. CONCLUSION: Foci of malignant tumor are not uncommon in prophylactic oophorectomies performed in women at very high risk for ovarian cancer and may not be detected on ultrasonograms. Surgeons should have a high suspicion of finding cancer in these women at the time of prophylactic surgery, and careful pathologic assessment of the specimens should be conducted.

Differential expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 protein and mRNA in epithelial ovarian tumors.

OBJECTIVE: Matrix metalloproteinase-9 (MMP-9) can degrade gelatin and type IV collagen and is known to play an important role in tumor cell invasion across the basement membrane. The tissue inhibitor of metalloproteinase-1 (TIMP-1) is able to prevent activation of pro-MMP-9 and forms a 1:1 complex with the active form of MMP-9. The aim of the present study was to investigate the expression of MMP-9 and TIMP-1 in benign, borderline, and invasive epithelial ovarian tumors. MATERIALS AND METHODS: A total of 90 patients with epithelial ovarian tumor were treated at the Brigham and Women's Hospital and were used as the study population. Immunohistochemistry and in situ hybridization were performed to detect protein and mRNA expression of MMP-9 and TIMP-1. RESULTS: In the 90 epithelial ovarian tumors tested, MMP-9 expression in tumor cells was found to be significantly enhanced in serous and mucinous ovarian carcinomas compared with benign and borderline tumors. We also observed the immunostaining of MMP-9 in stromal cells of benign, borderline, and invasive epithelial ovarian tumors. Moreover, the expression levels of TIMP-1 in tumor cells were significantly higher in borderline and invasive ovarian tumors than in benign tumors. CONCLUSION: Using an in situ hybridization technique, we disclosed a direct correlation between the presence of mRNA and protein expression for both MMP-9 and TIMP-1. The present data suggest that high levels of MMP-9 protein in invasive epithelial ovarian carcinoma are strongly associated with tumor cell invasion. Enhanced expression of TIMP-1 protein in borderline and invasive tumors indicates that endogenous TIMP-1 protein may play a paradoxical role in ovarian tumor progression.

Identification of a novel 9 cM deletion unit on chromosome 6q23-24 in papillary serous carcinoma of the peritoneum.

To define regions of deletion on chromosome 6q in papillary serous carcinoma of the peritoneum (PSCP), we analyzed 103 tumor tissues from 53 patients by using 11 polymorphic microsatellite markers spanning loci from 6q23 to 6q27. Allelic losses on 6q were observed in 42 of 53 (79.2%) cases. We identified 3 distinct regions with a high percentage (>40%) of loss of heterozygosity. The first region is located at 6q23-24 and defined by D6S311 (15 of 35 informative cases, 42.9%). Detailed deletion mapping of chromosome 6q23-24 in these tumor samples identified a novel 9 cM minimal deletion region flanked by D6S250 and ESR. The second one is located at 6q25.1-25.2 and defined by D6S448 (17 of 36 informative cases, 47.2%). A second minimal deletion region of 4 cM was flanked by D6S420 and D6S442. The third region is located at 6q27 and defined by D6S297 (9 of 19 informative cases, 47.4%). Comparing these results with our cases of advanced staged invasive serous epithelial ovarian carcinoma (SEOC), we observed that allelic losses at D6S311 (6q23) and D6S149 (6q27) were significantly higher for PSCP than for SEOC. The pattern of allelic loss at each tumor site within an individual patient was also studied. A total of 36 cases displayed allelic loss for at least 1 of multiple tumor sites, and 35 of these patients exhibited nonidentical patterns of allelic loss at various tumor sites of the same patient. Furthermore, an alternating pattern of allelic loss in the same patient was identified in 3 of 53 patients studied. These results show that allelic losses on 6q are very frequent in PSCP, and we show 2 discrete minimal deletion regions on 6q, suggesting the existence of at least 2 tumor suppressor genes within 6q that may be involved in the pathogenesis of PSCP. In addition, the finding of different patterns of allelic loss at different tumor sites within the same patient indicate a mutifocal origin in some PSCP cases. These results provide strong evidence to support our previous reports that PSCP is a multifocal disease entity.

BRCA1-related papillary serous carcinoma of the peritoneum has a unique molecular pathogenesis.

Papillary serous carcinoma of the peritoneum (PSCP) is believed to develop de novo from the peritoneal lining of the pelvis and abdomen. Although it is histologically indistinguishable from serous ovarian carcinoma, PSCP exhibits minimal or absent ovarian involvement and may even develop in a woman years after prophylactic oophorectomy. We have shown previously that patients with germ-line BRCA1 mutations who develop PSCP are more likely to have disease originating from multiple peritoneal sites compared with patients with wild-type BRCA1. In this study, we tested the hypothesis that BRCA1-related PSCP has a unique molecular pathogenesis. DNA was extracted from normal tissue and multiple tumor sites in patients with PSCP. BRCA1 and p53 gene mutations were screened for using single-strand conformation polymorphism. Loss of heterozygosity was determined at the BRCA1 and p53 loci. Immunohistochemical analyses of p53, epidermal growth factor receptor, erbB-2, erbB-3, erbB-4, and Bcl-2 expression were performed. We detected germ-line BRCA1 mutations in 11 (26%) of 43 PSCP patients. BRCA1 mutation carriers had a higher overall incidence of p53 mutations (89% versus 47%; P = 0.052), were more likely to exhibit multifocal or null p53 mutations (63% versus 7%; P = 0.014), and were less likely to exhibit erbB-2 overexpression (P = 0.013) than wild-type BRCA1 case subjects. We propose that the unique molecular pathogenesis of BRCA1-related PSCP may affect the ability of current methods to reliably prevent or detect this disease prior to metastasis.

ras gene activation and infrequent mutation in papillary serous carcinoma of the peritoneum.

OBJECTIVE: The ras genes are a well-studied family of proto-oncogenes whose involvement in many cancers has been delineated. However, K-ras mutations have not previously been examined in papillary serous carcinoma of the peritoneum (PSCP), a tumor which resembles serous epithelial ovarian carcinoma (SEOC) both in histology and epidemiology. In this study we examine the role of the K-ras oncogene in PSCP compared to SEOC. METHODS: Using single-strand conformational polymorphism analysis and cycle sequencing protocols, we evaluated our collection of 51 cases of PSCP for K-ras mutations and compared these findings with the experience in SEOC. We then examined 5 cases of PSCP for activation of ras proteins and MAP kinase to evaluate the potential involvement of the ras pathway in PSCP tumorigenesis. RESULTS: We found only one K-ras mutation in our 51 cases (2%) of PSCP compared to three mutations in 46 cases (6.5%) of high-grade, late-stage SEOC. This was not significantly different (P > 0.10). In the single PSCP case with a K-ras mutation, the mutation was found in only one of five tumor sites tested. All four mutations involved a single nucleotide alteration in codon 12 (GGT to GTT, Gly to Val). To evaluate the ras pathway in PSCP, we used the known activated ras binding domain on Raf-1 to perform an assay to test for activated ras. We identified ras activation in 4 of 5 PSCP cases tested and, to confirm that the activation was functional, we tested and found similar activation of MAP kinase, a downstream mediator for K-ras expression. CONCLUSIONS: K-ras mutations occur at low rates in both PSCP and high-grade, late-stage SEOC, and therefore K-ras mutations are not involved in the development of these two diseases. Finding the mutation in only one of multiple tumor sites in the PSCP case supports growing evidence for a multifocal origin of PSCP. Our findings of ras activation in four of five cases of PSCP suggest that ras activation by mechanisms other than genetic mutation is important for PSCP tumorigenesis.

A case-control study of galactose consumption and metabolism in relation to ovarian cancer.

Consumption or metabolism of dairy sugar and ovarian cancer have been linked based on evidence that galactose may be toxic to ovarian germ cells and that ovarian cancer is induced in animals by depletion of oocytes. We assessed consumption of dairy products and obtained blood for biochemical and molecular genetic assessment of galactose metabolism in 563 women with newly diagnosed epithelial ovarian cancer and 523 control women selected either by random digit dialing or through lists of residents in eastern Massachusetts and New Hampshire. We observed no significant differences between cases and controls in usual consumption of various types of dairy products or total daily lactose (the principal source of galactose in the diet); nor did we find that RBC activity of either galactose-1-phosphate uridyl transferase (GALT) or galactokinase differed. The mean (and SE) activity of uridine diphospho-galactose 4'-epimerase (in micromoles per hour per gram of hemoglobin) was, however, significantly lower (P < 0.005) in cases compared with controls, 20.32 (0.31) versus 21.64 (0.36). Ovarian cancer cases were also more likely to carry the N314D polymorphism of the GALT gene, generally predisposing to lower GALT activity. The difference was most evident for endometrioid and clear cell types of ovarian cancer, in which 3.9% of cases were found to be homozygous for N314D compared with 0.4% of controls, yielding an odds ratio and 95% confidence interval of 14.17 (2.62-76.60). We conclude that, whereas adult consumption of lactose carries no clear risk for the disease, certain genetic or biochemical features of galactose metabolism may influence disease risk for particular types of ovarian cancer.

Genetic alterations of the WT1 gene in papillary serous carcinoma of the peritoneum.

OBJECTIVE: The Wilms' tumor (WT1) gene product is consistently detectable in both normal ovarian germinal epithelium and human mesothelium. Ovarian carcinomas frequently exhibit alterations in WT1 function. Papillary serous carcinoma of the peritoneum (PSCP) is believed to develop de novo from the peritoneal lining (mesothelium) of the pelvis and abdomen. The purpose of this study was to determine if genetic alterations of the WT1 gene are associated with the development of PSCP. METHODS: Normal and tumor tissue specimens were retrieved from patients with stage III and IV PSCP (n = 38) and serous epithelial ovarian carcinoma (n = 38). Immunohistochemistry was performed using the anti-WT1 (C-19) antibody. Loss of heterozygosity (LOH) was performed at the WT1 locus. Clinical data were obtained and correlated with molecular findings. RESULTS: Loss of normal WT1 expression was detected in 18 (51%) of 35 PSCP specimens and 18 (53%) of 34 ovarian carcinoma specimens. Six (27%) of 22 PSCP specimens and 3 (13%) of 24 ovarian carcinoma specimens had LOH at the WT1 locus (P = 0.27). Normal WT1 gene expression was maintained in 86% of tumors exhibiting LOH. Genetic alterations of the WT1 gene were not predictive of survival, nor were they associated with other clinical or molecular factors. CONCLUSIONS: Genetic alterations of the WT1 gene are associated with the development of PSCP. The loss of normal WT1 gene expression is a common event in both PSCP and advanced ovarian carcinoma, likely resulting from down-regulation by other regulatory factors-not from inactivating gene mutation and subsequent allelic loss.

Bcl-2 and p53 protein expression, apoptosis, and p53 mutation in human epithelial ovarian cancers.

Bcl-2 and p53 gene products have been both linked to cell death by apoptosis. In the present study, we examined the relationship of Bcl-2 and p53 protein expression, p53 mutation and apoptosis in normal human ovaries and different types of human ovarian epithelial tumors by immunohistochemical localization, in situ terminal transferase-mediated dUTP nick end labeling and polymerase chain reaction-single strand conformation polymorphism. It was found that Bcl-2 expressed strongly in the surface epithelium of normal ovaries and benign and borderline ovarian tumors but weakly in the malignant tumors. On the contrary, strong protein expression of p53 was found in 54% (25/46) of the malignant epithelial tumors examined but similar expression of p53 was not observed in borderline and benign tumors and normal ovarian surface epithelium. A significant inverse correlation between Bcl-2 and p53 expression was found in the malignant ovarian tumors examined. p53 gene mutation at exons 5-11 was however not a pre-requisite for p53 expression in both borderline and malignant tumors. Apoptotic activities, as reflected by apoptotic indices, were low in normal ovarian surface epithelium and benign tumors but were increased in borderline and malignant tumors, with the highest average apoptotic index found in grade III malignant tumors. Statistical analyses showed a positive correlation between apoptosis and p53 expression, but similar correlation was not found between apoptosis and Bcl-2 expression. Our results also indicate that although expression of Bcl-2 is important during ovarian carcinogenesis, the Bcl-2 protein may have other roles to play apart from being a modulator of apoptosis in human ovarian epithelial cancers.

Genital talc exposure and risk of ovarian cancer.

Epidemiologic studies have suggested an increased risk for ovarian cancer associated with the use of talcum powder in genital hygiene, but the biologic credibility of the association has been questioned. We conducted a population-based case-control study in eastern Massachusetts and New Hampshire involving 563 women with newly diagnosed epithelial ovarian cancer and 523 control women selected either by random digit dialing or through lists of residents. Use of body powders was assessed through personal interview and the exposure odds ratio (OR) for the use of talc in genital hygiene was calculated. Cases were more likely than controls (45% vs. 36%) to have used talc as a body powder in some manner, and the excess was confined to patients who used talc on the perineum directly or as a dusting powder to underwear or sanitary napkins. Relative to women who never used body powder or used it only in non-genital areas, the OR (and 95% confidence interval) associated with genital exposure to talc was 1.60 (1.18 and 2. 15) after adjustment for age, study location, parity, oral contraceptive use, body mass index and family history of breast or ovarian cancer. Exposure prior to rather than after a first livebirth appeared to be more harmful, and the association was most apparent for women with invasive serous cancers and least apparent for those with mucinous tumors. We conclude that there is a significant association between the use of talc in genital hygiene and risk of epithelial ovarian cancer that, when viewed in perspective of published data on this association, warrants more formal public health warnings.

Differential expression of NF1 type I and type II isoforms in sporadic borderline and invasive epithelial ovarian tumors.

The NF1 gene, a putative tumor suppressor gene, contains a GAP related domain (GRD) which accelerates hydrolysis of ras-bound GTP to GDP, thereby converting the ras oncogene from its active to inactive form. Two forms of the NF1 GRD transcript (Type I and Type II) are differentially expressed in neuroectodermal tumor tissue relative to differentiated neural cells, and in gastric cancer cell lines relative to normal stomach mucosa. We measured relative expression of NF1 Type II and Type I isoforms in cultured normal and malignant human ovarian surface epithelial cells(HOSE) and in invasive and borderline ovarian tumor tissue. We demonstrated an 11-fold increase in Type II:Type I ratio in 7 HOSE cultures relative to eight ovarian cancer cell lines. Our findings indicate a significant decrease in Type II isoform expression and increase in Type I expression in ovarian cancer cells and tumor tissue relative to HOSE cells. We also demonstrate an increase in Type II:Type I ratio, and a decrease in cell proliferation rate in three ovarian cancer cell lines on treatment with retinoic acid. We propose that differential expression of the NF1 Type I and Type II isoforms is related to cellular differentiation in ovarian epithelial cancer and strategies based on alteration in NF1 isoform expression may have therapeutic potential in ovarian malignancies.

Perineural invasion in prostate needle biopsy specimens. Correlation with extraprostatic extension at resection.

The significance of perineural invasion in prostate needle biopsy specimens for predicting extraprostatic extension is controversial. We correlated the presence of perineural invasion in needle biopsy specimens from 340 men with the presence of extraprostatic extension in corresponding radical prostatectomy specimens. Perineural invasion was present in 57 biopsy specimens. The sensitivity of perineural invasion for predicting extraprostatic extension was 32%, the specificity 88%, and the positive predictive value 42%. Biopsy specimens with perineural invasion had significantly more core specimens involved with tumor and higher biopsy-determined Gleason scores than those without invasion. Biopsy specimens with perineural invasion were significantly more likely to show extraprostatic extension and Gleason scores were higher in the resection specimens than those without perineural invasion. Multivariate logistic regression analysis showed that perineural invasion remained an independent predictor of extraprostatic extension. However, in multivariate analysis, including preoperative serum prostate-specific antigen (PSA) for 173 of the patients, the only independent predictor of extraprostatic extension was PSA. While perineural invasion in biopsy specimens is a predictor of extraprostatic extension at resection that is independent of other histologic features, the positive predictive value is low and it is not an independent predictor when serum PSA is included.

Genetic imbalance on chromosome 17 in papillary serous carcinoma of the peritoneum.

We extend the evaluation of allelic loss patterns on chromosome 17 to papillary serous carcinoma of the peritoneum (PSCP) which is histologically identical to papillary serous ovarian carcinoma (PSOC). DNA was obtained from 11 archival cases of PSCP, with 1-11 tumor sites per case. Using ten loci spanning chromosome 17, loss of heterozygosity (LOH) was identified in all 11 cases (100%). Furthermore, 75-100% of informative cases exhibited LOH at the loci p53, D17S1322 (intragenic to the tumor suppressor gene BRCA1), D17S1327 and MPO. PSCP cases exhibit a higher rate of LOH at most loci when compared with PSOC. Alternating allelic loss at different tumor sites was identified in three cases supporting a multifocal origin of PSCP. Microsatellite instability (MI) is an uncommon event which was identified in four cases. These data implicate chromosome 17 as a potential location of genetic events important in the pathogenesis of PSCP as well as ovarian cancer.

Paraovarian cystadenomas and cystadenofibromas: sonographic characteristics in 14 cases.

PURPOSE: To describe the sonographic features of paraovarian cystadenomas. MATERIALS AND METHODS: We searched the computerized pathology and radiology databases for cases of histopathologically proved paraovarian cystadenomas from January 1993 through December 1996 in which preoperative sonography had also been performed. Fourteen paraovarian cystadenomas or cystadenofibromas were identified in 14 patients aged 20-57 years. Sonographic and pathologic findings were correlated. RESULTS: Three of the masses appeared as simple cysts sonographically. Of the remaining 11 masses, nine had solid nodular areas within the cyst; three had septations; and four had a thick wall, an irregular wall, or both at sonography. At sonography, four masses were thought to arise outside the ovary, four were erroneously thought to arise in the ovary, and the location was uncertain in six. CONCLUSION: Paraovarian cystadenomas are cystic masses that usually contain one or more small solid nodules and occasionally contain septations.

Molecular evidence for multifocal papillary serous carcinoma of the peritoneum in patients with germline BRCA1 mutations.

BACKGROUND: Papillary serous carcinoma of the peritoneum (PSCP) diffusely involves peritoneal surfaces, while it spares or only superficially involves the ovaries. PSCP is histologically indistinguishable from serous epithelial ovarian carcinoma, and it may develop years after oophorectomy. The molecular pathogenesis of PSCP remains unresolved, although preliminary data suggest a multifocal origin in some cases. Patients with germline BRCA1 mutations may develop PSCP in addition to breast and ovarian carcinomas. The purpose of this study was to utilize the androgen receptor (AR) gene locus to test the hypothesis that some cases of PSCP have a multifocal origin and to determine if patients with germline BRCA1 mutations develop multifocal PSCP. METHODS: Specimens of normal and tumor tissues from 22 women with PSCP were obtained, and DNA was extracted. The AR gene locus was evaluated for patterns of loss of heterozygosity (LOH) and X-chromosome inactivation. The methylation-sensitive Hpa II restriction enzyme was used to differentiate the active and inactive X chromosomes. Germline BRCA1 mutation status of the patients was determined previously. RESULTS: Genetic analysis of tumor specimens indicated that five (23%) of 22 case subjects had patterns of selective LOH at the AR locus, consistent with multifocal, polyclonal disease origin. Two patients with selective LOH also had alternating X-chromosome inactivation patterns. Patients with germline BRCA1 mutations were more likely to have evidence of multifocal disease (two-sided Fisher's exact test, P = .01). CONCLUSIONS: Our results show that PSCP has a multifocal origin in at least some cases. Furthermore, patients with germline BRCA1 mutations are more likely to develop multifocal PSCP than are patients without BRCA1 mutations.

Evidence for the multifocal origin of bilateral and advanced human serous borderline ovarian tumors.

Borderline ovarian tumors (BOTs), or ovarian tumors of low malignant potential, represent a distinct category of epithelial ovarian neoplasms that have a clinically more favorable outcome than invasive epithelial ovarian cancer. Histologically, BOTs and invasive ovarian carcinomas both show cellular proliferation and pleomorphism, but unlike invasive ovarian carcinomas, BOTs lack stromal invasion. Although serous BOTs are frequently confined to a single ovary at the time of diagnosis, bilateral or extra-ovarian spread occurs in 30-40% of cases. The purpose of this study is to determine whether bilateral or extraovarian serous borderline lesions are metastatic sites from the original tumor, or represent separate primary tumors. DNA specimens from multiple tumor sites and normal tissue controls were obtained in eight women with bilateral or extra-ovarian serous borderline tumors. The pattern of loss of heterozygosity at the androgen receptor locus on the X chromosome was evaluated in the multiple tumor sites. In addition, the pattern of X-chromosome inactivation was determined using HpaII restriction endonuclease digestion, followed by PCR amplification of the androgen receptor locus. Multifocality was determined when alternate patterns of X-chromosome inactivation occurred. In two of the eight patients, the left and right ovarian tumor sites had different androgen receptor alleles inactivated, indicating that the bilateral tumors derived independently. In a third patient, the X inactivation pattern in the left ovarian tumor differed from the two peritoneal implants, suggesting that the implants were separate primary tumors, and not metastatic, from the left ovarian tumor. The remaining five patients had the same pattern of loss of heterozygosity and X inactivation in the tumor sites studied. These results suggest that bilateral and advanced stage serous BOTs may be multifocal in origin. This result is in contrast to invasive epithelial ovarian cancer, which has been shown to be unifocal in origin.

A novel 4 cM minimal deletion unit on chromosome 6q25.1-q25.2 associated with high grade invasive epithelial ovarian carcinomas.

Detailed deletion mapping of chromosome 6q has shown that the highest percentage of loss of heterozygosity (LOH) is located at 6q25-q27 and suggested that an ovarian cancer associated tumor suppressor gene may reside in this region. To further define the smallest region of common loss, we used 12 tandem repeat markers spanning a region no more than 18 cM, located between 6q25.1 and 6q26, to examine allelic loss in 54 fresh and paraffin embedded invasive ovarian epithelial tumor tissues. Loss of heterozygosity was observed more frequently at the loci defined by marker D6S473 (14 of 32 informative cases, 44%) and marker D6S448 (17 of 40 informative cases, 43%). Detailed mapping of chromosome 6q25-q26 in these tumor samples identified a 4 cM minimal region of LOH between markers D6S473 and D6S448 (6q25.1-q25.2). Loss of heterozygosity at D6S473 correlated significantly both with serous versus non-serous ovarian tumors (P=0.040) and with high grade versus low grade specimens (P=0.023). The results suggest that a 4 cM deletion unit located at 6q25.1-q25.2 may contain the putative tumor suppressor gene which may play a role in the development and progression of human invasive epithelial ovarian carcinomas (IEOC).