Search PubMed⌕ Search

Biomedical subjects

M G Muto

Publications and source records attributed to M G Muto.

At least 37 records · Page 2Linked to original sources

Clinical and pathological features of ovarian cancer in women with germ-line mutations of BRCA1.

BACKGROUND: We tested the hypothesis that ovarian cancers associated with germ-line mutations of BRCA1 have distinct clinical and pathological features as compared with sporadic ovarian cancers. METHODS: We reviewed clinical and pathological data on patients with primary epithelial ovarian cancer found to have germ-line mutations of BRCA1. Survival among patients with advanced-stage cancer and such mutations was compared with that in control patients matched stage, grade, and histologic subtype of the tumors. A combination of single-strand conformation and sequencing analyses was used to examine the 22 coding exons and intronic splice-donor and splice-acceptor regions of BRCA1 for mutations in pathological specimens. Alternatively, some patients were known to be obligate carriers of the mutant BRCA1 gene because of their parental relationships with documented mutant-gene carriers. RESULTS: We identified 53 patients with germ-line mutations of BRCA1. The average age at diagnosis was 48 years (range, 28 to 78). Histologic examination in 43 of the 53 patients showed serous adenocarcinoma. Thirty-seven tumors were of grade 3, 11 were of grade 2, 2 were of grade 1, and 3 were of low malignant potential. In 38 patients, the tumors were of stage III; 9 patients (including those with tumors of low malignant potential) had stage I disease, 5 had stage IV, and 1 had stage II. As of June 1996, with a median follow-up among survivors of 71 months from diagnosis, 20 patients had died of ovarian cancer, 27 had no evidence of the disease, 4 were alive with the disease, and 2 had died of other diseases. Actuarial median survival for the 43 patients with and advanced-stage disease was 77 months, as compared with 29 months for the matched controls (P<0.001). CONCLUSIONS: As compared with sporadic ovarian cancers, cancers associated with BRCA1 mutation appear to have a significantly more favorable clinical course.

Actuarial Analysis↗

Frequent microsatellite instability in epithelial borderline ovarian tumors.

To further define the genetic events that could lead to the development of borderline ovarian tumors (BOTs), we analyzed 13 microsatellite markers on chromosomes 3p and q in 18 BOTs and compared the results to 31 serous invasive epithelia] ovarian cancers (IEOCs). Five of the 18 BOTs showed microsatellite instability (MSI) at one or more loci, compared to only 2 of the 31 IEOCs studied (P < 0.04). In two of these five BOTs, MSI was found in multiple loci. All BOTs with MSI were serous, while none of the mucinous type showed any alteration. Loss of heterozygosity was found in only 1 of the 18 BOTs, but in 12 of the 31 IEOCs (P < 0.01). This first report of a relatively high percentage of MSI in BOTs opens a wide spectrum of new hypotheses for borderline ovarian tumorigenesis as well as several new research avenues.

Base Sequence↗

Loss of heterozygosity of chromosome 17 in human borderline and invasive epithelial ovarian tumors.

Polymerase chain reaction (PCR) analysis of microsatellite polymorphisms corresponding to four loci which map to chromosome 17p and 11 loci which map to chromosome 17q was performed to screen for loss of heterozygosity (LOH) in paired normal and tumor tissues from 27 cases of borderline epithelial ovarian tumors (BEOT) and 32 cases of invasive epithelial ovarian cancers (IOC). LOH was observed in six of 27 (22%) of the borderline tumors and in 29 of 32 (90%) of the invasive ovarian cancers (P<0.001). At all 15 loci studied, a lower percentage of allelic loss was detected in borderline tumors (0-14%) vs invasive cancer (8-93%). At eight loci this difference was statistically significant. For IOC, one common loss region was identified on chromosome 17p and four distinct common loss regions were on chromosome 17q, which supports the notion that multiple tumor suppressors may reside on chromosome 17 in IOC. These data suggest that LOH on chromosome 17 is an infrequent event in BEOT compared with IOC and therefore may not be important in the distinct pathogenesis of BEOT.

Alleles↗

SPARC, an extracellular matrix protein with tumor-suppressing activity in human ovarian epithelial cells.

SPARC, also termed osteonectin, BM-40 and 43K protein, is an acidic, cysteine-rich component of the extracellular matrix that has been shown to be directly regulated by progesterone and dexamethasone and indirectly by cytokines. By RNA fingerprinting technique, we cloned a SPARC homolog from the normal human ovarian surface epithelial (HOSE) cells and demonstrated that it is expressed at high levels in the normal HOSE cells but at much lower levels in ovarian carcinoma cells in vitro and in vivo. Subsequently, we transfected the full length SPARC cDNA into an ovarian carcinoma cell line SKOV3 and showed that it reduced the growth rate of the cancer cell line in culture and reduced the cell's ability to induce tumours in nude mice. These results suggest that SPARC may play an important role in growth and and differentiation of the HOSE cells and support the hypothesis that SPARC functions as a tumor suppressor.

Animals↗

Frequency of the BRCA1 185delAG mutation among Jewish women with ovarian cancer and matched population controls.

Among women of Ashkenazi Jewish origin, a frameshift mutation of the BRCA1 gene, designated 185delAG, occurs with a carrier frequency of approximately 1% and is estimated to account for about 39% of ovarian cancer cases occurring prior to age 50 years. To determine the actual frequency of this mutation among Jewish women with ovarian cancer, we tested DNA collected as part of an ongoing population-based case-control study of genetic and environmental factors for epithelial ovarian cancer in eastern Massachusetts. Using single-stranded conformational polymorphism analysis followed by direct sequencing, we found that 6 (19.4%) of 31 Jewish patients were carriers for a 185delAG mutation compared to 0 of 23 Jewish controls (P=0.03) Using empiric logic [correction of logits], the estimated relative risk for ovarian cancer associated with a 185delAG mutation is 12.0. The average age of the 6 patients with mutations was 48.3 years, significantly younger than the average of 57.4 years observed for the 25 patients without the mutation (P-0.05). For ovarian cancer diagnosed prior to age 50 years, three (37.5%) of eight patients carried the mutation. None of the six patients with the mutation had a history consistent with hereditary breast ovarian cancer syndrome, although two had a personal history of prior cancer. Our results provide empiric conformation of the estimated prevalence of 185delAG mutations among Jewish women with ovarian cancer.

BRCA1 Protein↗

A 400 kb novel deletion unit centromeric to the BRCA1 gene in sporadic epithelial ovarian cancer.

Allelic deletions on chromosome 17q21 in sporadic ovarian cancer are common, suggesting that inactivation of a tumor suppressor gene(s) in that region may be important for the etiology of these tumors. The recently identified BRCA1 gene on 17q21, involved in the development of familial breast/ovarian cancer, could be a candidate. However, inactivating mutations on BRCA1 in sporadic ovarian cancer has been rarely described. Furthermore, the potential relationship of BRCA1 gene to ovarian tumors of borderline malignancy remains also unclear. We constructed a highly detailed deletion map of chromosome 17q21 based on PCR amplification of eight polymorphic tandem repeat markers in a 650 kb area including three BRCA1 intragenic markers. DNA from 52 sporadic ovarian cancers and 26 borderline tumors, together with their corresponding normal control tissues were used. Only one borderline tumor showed loss of heterozygosity at one marker, whereas 65% of invasive ovarian cancers displayed allelic loss in at least one of the markers studied. A common deletion unit, located approximately 60kb centromeric to BRCA1, was revealed. These results suggest that inactivation of the BRCA1 gene may not be responsible for the development of borderline ovarian tumors and that another tumor suppressor gene, located centromeric to the BRCA1 gene, may play a role in sporadic ovarian cancer development.

Alleles↗

Monoclonal antibodies used in the detection and treatment of epithelial ovarian cancer.

Conventional therapy for epithelial ovarian cancer, including aggressive cytoreductive surgery followed by combination chemotherapy regimens, has failed to reduce the number of deaths caused by this disease, which remains the most lethal of gynecologic malignancies. Monoclonal antibodies, which offer the promise of high selectivity for detection and therapy, may be targeted to tumor-associated antigens, growth factors, receptors, or oncogenes. They may be used alone as immunotherapeutic agents or conjugated to chemotherapeutic drugs, toxins, or radionuclides. Radioimmunoconjugates may also be used for preoperative or intraoperative tumor localization. The authors focused on the clinical utility, technical limitations, and potential of monoclonal antibodies in the detection and treatment of epithelial ovarian cancer with emphasis on radioimmunodetection and radioimmunotherapy.

Antibodies, Monoclonal↗

Evidence for a multifocal origin of papillary serous carcinoma of the peritoneum.

Histopathological evidence suggests that papillary serous carcinoma of the peritoneum (PSCP) may be multifocal in origin. Utilizing a PCR based method to detect tandem repeat polymorphisms in formalin fixed tissue, loss of heterozygosity at eight loci on chromosomes 1, 3, 4, and 17 was studied in six cases of PSCP. Loss of heterozygosity was assessed at between 5 and 11 tumor sites/patient. Allelic losses at 4 loci (1q32-qter, 3p14.3-21.1, 17q12, 17q21.3-23) were noted. Three cases demonstrated a different pattern of allelic loss at various anatomic sites within the same patient. In an additional case, a mutation of the p53 gene, detected by quantitative PCR followed by single-strand conformation polymorphism analysis, was detected in only 2 of 5 tumor sites. The pattern of allelic loss and the mutational pattern of the p53 gene varied at tumor sites within the same patient in 4 of 6 cases of PSCP. These findings are consistent with histopathological evidence that PSCP is multifocal in origin.

Base Sequence↗

Characterization of human ovarian surface epithelial cells immortalized by human papilloma viral oncogenes (HPV-E6E7 ORFs).

Primary human ovarian surface epithelial (HOSE) cells were immortalized by a retroviral vector (LXSN-16E6E7) expressing HPV-E6E7 open reading frames (ORF). Immortalizations of primary ovarian epithelial cells were achieved in three of three attempts. Detailed analysis was carried out in one line, HOSE 6-3, selected on the basis of its epithelial morphology. The immortalized line (HOSE 6-3) was nontumorigenic in nude mice when examined at subculture number 20. Cytogenetic analysis confirmed its human origin and detailed karyotypic analysis revealed a mixed karyotype made up of about 60% of diploid and 40% of near-tetraploid cells. Clonal chromosomal aberration was observed in a subpopulation of cells involving a ring chromosome number 9. Immunofluorescence and two-dimensional gel electrophoresis revealed the presence of vimentin and several species of cytokeratin (K7, K8, K18, K19). The profile of the cytoskeletal filaments of HOSE 6-3 cells is largely identical with that of normal ovarian epithelial cells before immortalization. The immortalized ovarian epithelial cells have a lower sensitivity to TGF-beta 1 inhibition compared to normal ovarian epithelial cells. The immortalized line, HOSE 6-3, has altered growth properties including a higher proliferation rate, plating efficiency, and saturation density. The establishment of a continuous line of human ovarian epithelial cells may provide an in vitro model for study of carcinogenesis in human ovarian cancers.

Cell Division↗

Characteristics of women with a family history of ovarian cancer. I. Galactose consumption and metabolism.

BACKGROUND: Galactose metabolism may be a risk factor for ovarian cancer based upon evidence that galactose causes ovarian failure and that ovarian cancer arises from premature ovarian failure. This study examines galactose-1-phosphate uridyl transferase (GALT) activity in women with a family history of ovarian cancer (FOC) to determine if low GALT activity occurs in women who are at risk for but in whom ovarian cancer has not yet developed. METHODS: The authors studied 106 premenopausal women (FOC patients) with one primary or two second-degree relatives with ovarian cancer compared with 116 age matched control subjects without a family history of ovarian cancer (FOC controls). All women completed questionnaires and had blood drawn to measure GALT activity and genotype. RESULTS: Mean erythrocyte GALT activity, in micromoles of hexose conversion per hour per gram of hemoglobin was 21.5 in FOC patients, significantly lower than the mean of 23.1 observed in FOC control subjects, (P = 0.001). FOC patients more frequently displayed the Duarte variant of galactosemia as detected by electrophoresis. In a subset of 87 patients and 113 control subjects for whom DNA was available, the allelelic frequency of the Duarte variant based upon molecular genetic detection of the N314D mutation that is associated with the Duarte variant was 15.5% among FOC cases compared with 7.5% among control subjects (P < 0.02). Galactose consumption did not differ between FOC patients and control subjects. CONCLUSION: Galactose metabolism differs between women with and without a family history of ovarian cancer, suggesting that it may be a genetic risk factor for ovarian cancer, possibly mediated through oocyte toxicity from galactose.

Adult↗

Characteristics of women with a family history of ovarian cancer. II. Follicular phase hormone levels.

BACKGROUND: Although there is a basis for linking pituitary or ovarian hormones with experimentally induced ovarian cancer, establishing their role in women is complicated because the usual case-control methods cannot be applied. In this study, hormonal levels in women with a family history of ovarian cancer (FOC) and who are at higher risk for the disease are compared with women without such a history. METHODS: The authors studied 106 unrelated women (FOC patients) with at least one primary or two second-degree relatives with ovarian cancer compared with 116 age- and residence-matched controls without a family history of ovarian cancer (FOC control subjects). All women were premenopausal, between the ages of 25 and 49 years, not currently using oral contraceptives, and had blood drawn during the early follicular phase for gonadotropins, estradiol (E2), and CA-125. RESULTS: Women with a family history of ovarian cancer and control subjects did not differ significantly in follicle stimulating hormone (FSH) levels, E2, or CA-125. Patients with a family history of ovarian cancer had significantly lower luteinizing hormone (LH) levels compared with control subjects and produced more E2 and FSH relative to their level of LH. The ratios of LH to E2 and LH to FSH were correlated with the enzymatic activity of galactose-1-phosphate uridyl transferase, which was shown previously to differ between FOC patients and control subjects. CONCLUSION: Lower LH and higher E2 are reported in women with breast, endometrial, and ovarian cancer (before surgery). The authors speculate that these observations reflect greater LH binding and estradiol production in ovaries at risk for these cancers--the ovarian cortical hyperplasia postulated in older gynecologic literature as the precursor to estrogen dependent neoplasia.

Adult↗

Ovarian masses: can benign and malignant lesions be differentiated with color and pulsed Doppler US?

PURPOSE: To determine whether color and pulsed Doppler ultrasound (US) can be used to differentiate benign from malignant ovarian masses. MATERIALS AND METHODS: Forty-four ovarian masses identified with sonography in 40 patients were confirmed at surgery (n = 35) or followed up to resolution with US (n = 9). Color and pulsed Doppler US were used to calculate the lowest pulsatility index (PI) and resistance index (RI) for each mass. RESULTS: Color Doppler US enabled detection of arterial flow in 24 of 36 benign masses and six of eight malignant masses. PI was lower in malignant masses than in benign masses (P = .002), as was RI (P = .001). Both indexes demonstrated overlap between benign and malignant masses; therefore, no cutoff value for either index had both high sensitivity and high specificity for malignancy: For PI cutoff of 1.0, sensitivity and specificity were 100% and 46%, respectively; for RI cutoff of 0.4, 50% and 96%. CONCLUSIONS: While PI and RI tend to be lower in malignant ovarian masses, neither index can be used reliably to differentiate benign from malignant lesions. In addition, lack of detectable flow by means of color Doppler US does not exclude ovarian malignancy.

Adult↗

Mutation of K-ras protooncogene in human ovarian epithelial tumors of borderline malignancy.

The mutation of K-ras protooncogene was examined in 44 cases of borderline ovarian epithelial tumors and 18 cases of invasive ovarian carcinomas. In borderline tumors, K-ras mutations are a common feature, having been found in 21 of 44 cases (48%). Twenty of the 21 mutations were identified at codon 12, and one was identified at codon 13. A detailed analysis of the mutation pattern of K-ras revealed a close association with the histological cell types of the tumor. Mutation of K-ras was detected at a higher frequency in mucinous borderline tumor (identified in 12 of 19 cases) compared to serous borderline tumor (identified in 9 of 25 cases). K-ras mutation was also detected in invasive mucinous and serous ovarian carcinomas, hence supporting the notion that borderline ovarian tumors may represent a pathological continuum between benign and frankly invasive diseases.

Adenocarcinoma, Mucinous↗

Molecular genetic evidence of a unifocal origin for human serous ovarian carcinomas.

The hypothesis that ovarian cancer is multifocal in origin was examined using molecular genetic techniques. Patterns of allelic deletion on chromosome 17 were studied in 16 informative cases of Stage III serous epithelial ovarian carcinoma. DNA was extracted from specimens collected from the omentum and both ovaries, and the specific alleles and chromosomal loci involved in the deletion were identified and compared. In all cases, the patterns of allelic deletion were identical for the tumors that had been collected from different sites in the same patients. In addition, 4 of the 16 cases were heterozygous for the hypoxanthine phosphoribosyl transferase (HPRT) gene on the X-chromosome and were examined for methylation status. In all 4, the same parental allele of the HPRT gene was methylated in tumor cells collected from both ovarian and omental sites, suggesting that the patterns of inactivation of the X-chromosome are identical. This pattern of allelic deletion and HPRT-gene methylation in tumor samples collected from different sites implies that ovarian carcinomas have a unifocal origin.

Alleles↗

Screening for ovarian cancer: the preliminary experience of a familial ovarian cancer center.

Women with a family history of ovarian cancer represent a high-risk group for the development of epithelial ovarian cancer. From July 1990 through December 1992, 386 women with a first-degree or multiple second-degree relatives with confirmed ovarian cancer were enrolled in a study to assess the utility of screening with transvaginal sonography, color flow doppler, and CA125. The mean age of the group was 41; 85% were premenopausal and 89/384 (23%) had 2 or more relatives with ovarian cancer. An initial ultrasound examination was abnormal in 89/384 (23%), 89% of whom were premenopausal. A persistent ovarian mass was detected in 15 patients and all were surgically proven to be benign. Mean CA125 levels were significantly higher and more variable in pre- vs postmenopausal women. CA125 was > or = 35 U/ml in 42/386 (11%) (36-232 U/ml). All but one of these women were premenopausal and 50% subsequently normalized. Two patients who were surgically explored for a rising CA125 had normal ovaries. An additional 19 patients have undergone prophylactic oophorectomy with no consistent histopathologic abnormality identified. These data demonstrate the difficulty inherent in screening a predominantly premenopausal population and do not clearly establish the efficacy of these modalities in the early detection of ovarian cancer.

Adult↗

The role of cytoreductive surgery in the management of stage IV epithelial ovarian carcinoma.

Patients with Stage IV epithelial ovarian carcinoma are generally treated in the same manner as are patients with disease confined to the abdomen--cytoreductive surgery followed by combination chemotherapy. Between 1980 and 1990, 35 women with histologically or cytologically documented Stage IV ovarian carcinoma were treated in this fashion. Sixteen women (45%) underwent optimal initial cytoreductive surgery, defined as less than 2 cm maximum residual disease. Eleven of the 19 women undergoing suboptimal initial procedures underwent interval cytoreduction after two to four cycles of chemotherapy, with 7 achieving an optimal status after the interval procedure. Overall, 23 of 35 patients (66%) were successfully cytoreduced to less than 2 cm either initially or at an interval procedure. Thirty-one of the 35 patients received combination regimens containing platinum as part of their initial therapy. Kaplan-Meier survival curves demonstrated no significant difference in survival between those groups of women cytoreduced intervally or initially, or between those groups of women optimally cytoreduced at some point during their initial therapy and those who were not. The 5-year survival for the entire group was less than 5%, with no significantly prolonged survival seen in those patients undergoing successful cytoreduction.

Chemotherapy, Adjuvant↗

Preoperative serum CA-125 levels in borderline tumors of the ovary.

Preoperative serum CA-125 levels were evaluated in 38 patients who underwent primary surgery for epithelial ovarian tumors of borderline malignancy at the Brigham and Women's Hospital and Massachusetts General Hospital between 1981 and 1990. Surgical staging was Stage I in 25 (66%) patients, Stage II in 2 (5%) patients, Stage III in 10 (26%) patients, and Stage IV in 1 (3%) patient. The mean sizes of mucinous and serous ovarian tumors were 21.9 and 10.3 cm, respectively (P = 0.0002). All 13 patients (100%) with mucinous tumors had Stage I disease, while 12 (50%) of 24 patients with serous tumors were Stage I. Combining all cell types, 10 (40%) of 25 patients with Stage I disease had an elevated preoperative CA-125 level, while 2 (100%) of 2, 9 (90%) of 10, and 1 (100%) of 1 patient with Stage II, III, and IV disease, respectively, had increased preoperative levels. Among patients with serous tumors, 3 (25%) of 12 Stage I patients had an elevated preoperative CA-125 level, while 11 (92%) of 12 Stage II-IV tumors had elevated levels (P less than 0.001). These data suggest that preoperative CA-125 level correlates with stage of disease in patients with serous borderline ovarian tumors.

Adult↗