Identification of allelic losses in benign, borderline, and invasive epithelial ovarian tumors and correlation with clinical outcome

Prevalence of S-methyl-5'-thioadenosine Phosphorylase (MTAP) Deficiency in Human Cancer: A Tissue Microarray Study on 13,067 Tumors From 149 Different Tumor Types

Loss of S-methyl-5'-thioadenosine phosphorylase (MTAP) expression is a common event in cancer leading to a critical vulnerability of cancer cells towards anti-cancer drugs. Homozygous MTAP deletions result in a complete expression loss that can be detected by immunohistochemistry (IHC). In this study, a tissue microarray containing 17,078 samples from 149 different tumor entities was analyzed by IHC, and complete MTAP loss was validated by fluorescence in situ hybridization. MTAP loss was observed in 83 of 149 tumor categories, including neuroendocrine neoplasms (up to 80%), Hodgkin lymphoma (50.0%), mesothelioma (32.0% to 36.8%), gastro-intestinal adenocarcinoma (4.0% to 40.5%), urothelial neoplasms (10.5% to 36.7%), squamous cell carcinomas (up to 38%), and various types of sarcomas (up to 20%) and non-Hodgkin lymphomas (up to 14%). Homozygous MTAP deletion was found in 90% to 100% of cases with MTAP expression loss in most tumor categories. However, neuroendocrine tumors, Hodgkin lymphomas, and other lymphomas lacked MTAP deletions. MTAP deficiency was significantly linked to unfavorable tumor phenotype in selected tumor entities and the presence of PD-L1 expression on tumor cells, absence of PD-L1 expression on immune cells, and a low density of CD8 + lymphocytes. In summary, MTAP deficiency can occur in various tumor entities and is linked to unfavorable tumor phenotype and noninflamed tumor microenvironment, but is not always related to deletions. MTAP IHC is of considerable diagnostic value for the detection of neoplastic transformation in multiple different applications.

Integrating network pharmacology and Mendelian randomization to explore potential targets of matrine against ovarian cancer

BACKGROUND

Matrine has been reported inhibitory effects on ovarian cancer (OC) cell progression, development, and apoptosis. However, the molecular targets of matrine against OC and the underlying mechanisms of action remain elusive.

OBJECTIVE

This study endeavors to unveil the potential targets of matrine against OC and to explore the intricate relationships between these targets and the pathogenesis of OC.

METHODS

The effects of matrine on the OC cells (A2780 and AKOV3) viability, apoptosis, migration, and invasion was investigated through CCK-8, flow cytometry, wound healing, and Transwell analyses, respectively. Next, Matrine-related targets, OC-related genes, and ribonucleic acid (RNA) sequence data were harnessed from publicly available databases. Differentially expressed analyses, protein-protein interaction (PPI) network, and Venn diagram were involved to unravel the core targets of matrine against OC. Leveraging the GEPIA database, we further validated the expression levels of these core targets between OC cases and controls. Mendelian randomization (MR) study was implemented to delve into potential causal associations between core targets and OC. The AutoDock software was used for molecular docking, and its results were further validated using RT-qPCR in OC cell lines.

RESULTS

Matrine reduced the cell viability, migration, invasion and increased the cell apoptosis of A2780 and AKOV3 cells (P< 0.01). A PPI network with 578 interactions among 105 candidate targets was developed. Finally, six core targets (TP53, CCND1, STAT3, LI1B, VEGFA, and CCL2) were derived, among which five core targets (TP53, CCND1, LI1B, VEGFA, and CCL2) differential expressed in OC and control samples were further picked for MR analysis. The results revealed that CCND1 and TP53 were risk factors for OC. Molecular docking analysis demonstrated that matrine had good potential to bind to TP53, CCND1, and IL1B. Moreover, matrine reduced the expression of CCND1 and IL1B while elevating P53 expression in OC cell lines.

CONCLUSIONS

We identified six matrine-related targets against OC, offering novel insights into the molecular mechanisms underlying the therapeutic effects of matrine against OC. These findings provide valuable guidance for developing more efficient and targeted therapeutic approaches for treating OC.

Deregulated Metabolic Pathways in Ovarian Cancer: Cause and Consequence

Ovarian cancers are tumors that originate from the different cells of the ovary and account for almost 4% of all the cancers in women globally. More than 30 types of tumors have been identified based on the cellular origins. Epithelial ovarian cancer (EOC) is the most common and lethal type of ovarian cancer which can be further divided into high-grade serous, low-grade serous, endometrioid, clear cell, and mucinous carcinoma. Ovarian carcinogenesis has been long attributed to endometriosis which is a chronic inflammation of the reproductive tract leading to progressive accumulation of mutations. Due to the advent of multi-omics datasets, the consequences of somatic mutations and their role in altered tumor metabolism has been well elucidated. Several oncogenes and tumor suppressor genes have been implicated in the progression of ovarian cancer. In this review, we highlight the genetic alterations undergone by the key oncogenes and tumor suppressor genes responsible for the development of ovarian cancer. We also summarize the role of these oncogenes and tumor suppressor genes and their association with a deregulated network of fatty acid, glycolysis, tricarboxylic acid and amino acid metabolism in ovarian cancers. Identification of genomic and metabolic circuits will be useful in clinical stratification of patients with complex etiologies and in identifying drug targets for personalized therapies against cancer.

TP53 Mutations in Breast and Ovarian Cancer

Breast and ovarian cancers are the second and fifth leading causes of cancer deaths among women. Both breast and ovarian cancers are highly heterogeneous and are presented with diverse morphology, natural history, and response to therapy. In recent years, international efforts have led to extensive molecular characterization of both breast and ovarian tumors and identified biologically and clinically relevant subtypes of the diseases based on these molecular features. The role of TP53 in tumor initiation and progression is context dependent, and abrogation of the TP53 pathway seems to be essential for the development of basal-like breast cancers and high-grade serous ovarian cancers. These subtypes of breast and ovarian cancer show several genomic similarities including high frequency of TP53 mutation, which seems to be an early, initiating, and driving alteration in these cancer subtypes.

Genomic aberrations in borderline ovarian tumors

Background

According to the scientific literature, less than 30 borderline ovarian tumors have been karyotyped and less than 100 analyzed for genomic imbalances by CGH.

Methods

We report a series of borderline ovarian tumors (n = 23) analyzed by G-banding and karyotyping as well as high resolution CGH; in addition, the tumors were analyzed for microsatellite stability status and by FISH for possible 6q deletion.

Results

All informative tumors were microsatellite stable and none had a deletion in 6q27. All cases with an abnormal karyotype had simple chromosomal aberrations with +7 and +12 as the most common. In three tumors with single structural rearrangements, a common breakpoint in 3q13 was detected. The major copy number changes detected in the borderline tumors were gains from chromosome arms 2q, 6q, 8q, 9p, and 13q and losses from 1p, 12q, 14q, 15q, 16p, 17p, 17q, 19p, 19q, and 22q. The series included five pairs of bilateral tumors and, in two of these pairs, informative data were obtained as to their clonal relationship. In both pairs, similarities were found between the tumors from the right and left side, strongly indicating that bilaterality had occurred via a metastatic process. The bilateral tumors as a group showed more aberrations than did the unilateral ones, consistent with the view that bilaterality is a sign of more advanced disease.

Conclusion

Because some of the imbalances found in borderline ovarian tumors seem to be similar to imbalances already known from the more extensively studied overt ovarian carcinomas, we speculate that the subset of borderline tumors with detectable imbalances or karyotypic aberrations may contain a smaller subset of tumors with a tendency to develop a more malignant phenotype. The group of borderline tumors with no imbalances would, in this line of thinking, have less or no propensity for clonal evolution and development to full-blown carcinomas.

Tumor spreading to the contralateral ovary in bilateral ovarian carcinoma is a late event in clonal evolution

Cancer of the ovary is bilateral in 25%. Cytogenetic analysis could determine whether the disease in bilateral cases is metastatic or two separately occurring primary tumors, but karyotypic information comparing the two cancerous ovaries is limited to a single report with 11 informative cases. We present a series of 32 bilateral ovarian carcinoma cases, analyzed by karyotyping and high-resolution CGH. Our karyotypic findings showed that spreading to the contralateral ovary had occurred in bilateral ovarian cancer cases and that it was a late event in the clonal evolution of the tumors. This was confirmed by the large number of similar changes detected by HR-CGH in the different lesions from the same patient. The chromosomal bands most frequently involved in structural rearrangements were 19p13 (n = 12) and 19q13 (n = 11). The chromosomal bands most frequently gained by both tumorous ovaries were 5p14 (70%), 8q23-24 (65%), 1q23-24 (57%), and 12p12 (48%), whereas the most frequently lost bands were 17p11 (78%), 17p13 (74%), 17p12 (70%), 22q13 (61%), 8p21 and 19q13 (52%), and 8p22-23 (48%). This is the first time that 5p14 is seen gained at such a high frequency in cancer of the ovary; possibly oncogene(s) involved in bilateral ovarian carcinogenesis or tumor progression may reside in this band.

Construction of a chromosome 17 transcriptome in serous ovarian cancer identifies differentially expressed genes

Cytogenetic, molecular genetic, and functional analyses have implicated chromosome 17 genes in epithelial ovarian cancer (EOC). To further characterize the contribution of chromosome 17 genes in EOC, the Affymetrix U133A GeneChip was used to perform transcriptome analyses of 15 primary cultures of normal ovarian surface epithelial (NOSE) cells and 17 malignant ovarian tumor (TOV) samples of the serous histopathologic subtype. A two-way comparative analysis of 776 known genes and expressed sequences identified 253 genes that exhibited at least a threefold difference in expression in at least one TOV sample compared to the mean of NOSE samples. Within this data set, 99 of the 253 (39.1%) genes exhibited similar patterns of expression across all tested samples, suggesting a high degree of concordance in the chromosome 17 transcriptome. This observation was supported by hierarchical clustering analysis that segregated the TOV and NOSE samples into two separate groups. There were 77 genes that were differentially expressed in at least 50% of the TOV samples. Five genes (AdoRA(2B)at 17p12, CCL2 at 17q12, ACLY at 17q21.2, WIPI1 at 17q24.2, and SLC16A3 at 17q25.3) were significantly (P < 5.13E-11) differentially expressed at least threefold in all serous TOV samples, and all five genes were underexpressed in these TOV samples as compared to the NOSE samples. Interestingly, several of these differentially expressed genes have been previously associated with response to hypoxia.

Pigment epithelium-derived factor is estrogen sensitive and inhibits the growth of human ovarian cancer and ovarian surface epithelial cells

Epithelial ovarian carcinoma is the most lethal gynecological cancer. However, little is known about the molecular mechanisms underlying the disease development and progression. In this study, we found that the expression of pigment epithelium-derived factor (PEDF) was greatly reduced in ovarian tumors and in ovarian cancer cell lines when compared with their normal precursor, ovarian surface epithelium (OSE). In addition, we showed that exogenous PEDF inhibited the growth of cultured human OSE as well as ovarian cancer cell lines, whereas targeted inhibition of endogenous PEDF using small interfering RNA or neutralizing PEDF antibody promoted the growth of these cells, confirming that the growth-inhibitory effect was PEDF specific. We also report for the first time that estrogen is an important upstream regulator of PEDF in human OSE. Treatment of the cultured cells with 17 beta-estradiol (E2) inhibited the expression of PEDF protein and mRNA in a dose- and time-dependent manner, which could be reversed by the specific estrogen receptor antagonist, ICI 182,780, indicating that the regulation was estrogen receptor-mediated. We further showed that this down-regulation of PEDF gene transcription was a direct, primary effect of E2. E2 promoted OSE and ovarian cancer cell growth, whereas simultaneous treatment with E2 and PEDF abrogated the estrogenic growth stimulation of these cells. This study is the first to demonstrate a role of PEDF in OSE biology and ovarian cancer and suggests that the loss of PEDF may e of relevance in carcinogenesis.

Chromosome 2q24.2 is lost in sporadic but not in BRCA1-associated ovarian carcinomas

AIMS

Comparison between BRCA1-associated and sporadic ovarian carcinomas is a potential method to identify candidate modifier gene/s involved in the carcinogenic pathway of either or both groups. A previous study identified a significant difference in the frequency of copy number gain at 2q24-q32 by comparing BRCA1-associated and sporadic ovarian tumour specimens using comparative genomic hybridisation (CGH). The present study aimed to investigate the reported allelic imbalance at 2q24-32 by amplification of several microsatellite markers at the region by quantitative microsatellite analysis (QuMA) using Taqman at the same region identified as a site of allelic imbalance.

METHODS

The copy number of the genomic region in 2q24-32 was established in 21 BRCA1-associated ovarian carcinomas and 14 sporadic cases using quantitative microsatellite polymerase chain reaction (PCR). Statistical analysis was performed using permutation test analysis.

RESULTS

A significant loss at D2S156 marker (2q24.2) (p = 0.026) compared with the other three markers at 2q24-32 was found in the sporadic cohort but not in the BRCA1-associated group (p = 0.385).

CONCLUSIONS

Our data do not support the association between copy number gain at 2q24-32 and BRCA1 mutation status in ovarian cancers reported previously. The novel finding of the present study was significant loss at 2q24.2 in sporadic ovarian cancers.

Molecular mechanisms and biological plausibility underlying the malignant transformation of endometriosis: a critical analysis

Although population-based studies have unequivocally reported an increased risk of ovarian cancer in women with endometriosis, the biological evidence supporting the idea of endometriosis as a preneoplastic condition is scanty and not well substantiated. The fundamental features of human neoplasms (monoclonal growth, genetic changes, mutations in tumour suppressor genes and replicative advantage) have been evaluated in endometriotic lesions but results obtained are discordant. It is plausible that ectopic glands may expand monoclonally but the entity of this phenomenon is debated. According to some allelotyping studies, from one-third to one-half of endometriosis lesions would harbour somatic genetic changes in chromosomal regions supposed to contain genes involved in ovarian tumourigenesis, especially for the endometrioid histotype. These findings would be consistent with the progression model for carcinogenesis from the benign precursor to ovarian cancer but they could not be unequivocally replicated. Gene mutational studies are rare in this context. A single group has found missense mutations and deletions of PTEN gene in about 20% of ovarian endometriotic cysts. Moreover, in a model of genetically engineered mice harbouring an oncogenic allele of K-ras resulting in benign lesions reminiscent of endometriosis, a conditional deletion of PTEN caused the progression towards the endometrioid tumour. Based on these data, the causal link between endometriosis and ovarian endometrioid/clear cell carcinomas remains to be defined both in terms of entity of association and of underlying molecular mechanisms.

Serous and mucinous borderline (low malignant potential) tumors of the ovary

The prognosis for stage I serous borderline ovarian tumors (SBOTs) is thought to be excellent, despite rare, late recurrences. The behavior of advanced-stage SBOTs primarily depends on the invasiveness vs noninvasiveness of associated extraovarian implants. Pelvic and abdominal lymph node involvement and foci of microinvasion do not seem to adversely affect prognosis. Serous tumors with a micropapillary and/or cribriform growth pattern seem to be more frequently bilateral and exophytic and manifest at an advanced stage with a higher incidence of invasive implants than typical SBOTs. Molecular data suggest that such tumors may represent an intermediate stage in the typical SBOT-invasive low-grade serous carcinoma progression. Limited experience with endocervical (müllerian)-type mucinous borderline tumors shows a possible relation to SBOTs in clinicopathologic features and biologic behavior Intestinal-type mucinous borderline ovarian tumors (I-MBOTs) and well-differentiated mucinous carcinomas manifest at stage I in most cases; the prognosis is excellent. Mucinous tumors associated with pseudomyxoma peritonei are almost always secondary to similar tumors of the appendix or other gastrointestinal sites and should not be diagnosed as high-stage I-MBOTs. Rare primary ovarian mucinous tumors associated with pseudomyxoma peritonei are those arising in mature cystic teratomas. Advanced-stage ovarian mucinous carcinomas typically show frank, infiltrative-type invasion; the prognosis is poor.

Emerging role of RAB GTPases in cancer and human disease

Emerging evidence implicates alterations in the RAB small GTPases and their associated regulatory proteins and effectors in multiple human diseases including cancer. We have recently shown that RAB25, located at chromosome 1q22, is amplified at the DNA level and overexpressed at the RNA level in ovarian and breast cancer. These changes correlated with a worsened outcome in both diseases. In addition, enforced expression of RAB25 in both breast and ovarian cancer cells decreased apoptosis and increased proliferation and aggressiveness in vivo, potentially explaining the worsened prognosis. A better understanding of genetic alterations as well as the physiologic and pathophysiologic roles of RAB GTPases may open new opportunities for therapeutic intervention and better outcomes.

Mutational spectrum of p53 mutations in primary breast and ovarian tumors

Breast and ovarian cancers, like other cancers, occur due to genetic damage. Research aimed to determine the specific genes involved in the development of breast and ovarian cancers will help to understand how normal breast and ovarian epithelial cells escape regulation of proliferation, apoptosis and senescence. It was determined that approximately 10% of ovarian cancers and 20-30% of breast cancers arise in women who have inherited mutations in cancer susceptibility genes such as BRCA1, BRCA2 and other DNA repair genes. The ability to perform genetic testing permits the identification of women at increased risk who can then be offered preventive strategies. The vast majority of ovarian and breast cancers are sporadic, presumably resulting from the accumulation of genetic damage over lifetime. Several genes involved in breast and ovarian carcinogenesis have been identified, most notably the p53 tumor suppressor. The recent availability of expression microarrays has facilitated the simultaneous screening of thousands of genes and this will extend further the understanding of molecular events involved in the dynamic development of ovarian and breast cancers. Then, all this knowledge could be translated into effective screening, surveillance, prevention, and treatment strategies in the future.

Comparing the genetic changes detected in the primary and secondary tumor sites of ovarian cancer using comparative genomic hybridization

Our objective was to compare the genetic abnormalities in the primary tumors of epithelial ovarian cancer and their associated secondary peritoneal implants using comparative genomic hybridization (CGH). CGH was performed on seven apparent stage III ovarian serous cancer cases. Dissected tissue samples from the primary tumor and from the metastatic peritoneal implant were obtained at initial surgical staging and analyzed in each case. We used CGH as this technique allows the entire genome of the tumor to be examined simultaneously for chromosomal imbalances without the need for tissue culture or targeting of specific loci. The chromosomal abnormalities detected in the distinct sites were then reviewed and compared. CGH studies were successful in all 14 samples from the seven patients. The analysis revealed chromosomal aberrations in six patients with certain repeated changes as amplification of 1q, 2p, 2q, 3q, 6q, 8q, and 12p and underrepresentation of 18q and X chromosomes. Comparing the genomes of the primary tumors with the metastatic samples showed four cases with a balanced metastatic CGH profile while the primary site was aberrant. Greater chromosomal complexity associated with the primary site was detected in two other patients. In one case, both primary and secondary sites had no detectable chromosomal imbalances. The cytogenetic patterns in six of the seven primary tumors showed complex karyotypic changes, unlike the inconsistent findings that were associated with the secondary sites. The chromosomes of the secondary sites expressed either normal genomes or fewer genetic aberrations. Such genomic heterogeneity between the primary and secondary sites may indicate that the secondary peritoneal implants are de novo carcinogenesis occurrences. The results may support the concept that at least part of advanced ovarian cancer is a multicentric disease in the early stages. Further genetic studies are needed to reassess this assumption.

Analysis of Molecular Aberrations in Ovarian Cancer Allows Novel Target Identification

The completion of the Human Genome Project and recent advances in functional genomic, proteomic, and high-throughput screening methodologies have provided powerful tools for determining the mechanisms of human diseases, including complex polygenic diseases such as ovarian cancer. These developments may eventually lead to individualized molecular medicine, which is the treatment of patients based on the underlying genetic defects in their tumours and their own genetic makeup. A plethora of novel therapeutic agents that act on specific molecular targets defined by cancer genetics are under development. There is thus a great deal of interest in determining how specific genes and proteins function in cancers, in order to further the understanding of cancer initiation and progression; to aid in identifying biomarkers, therapeutic targets, and determinants of drug responsiveness; and to progress the development of novel antitumour agents.

FISH analysis of BRCA1 copy number in paraffin-embedded ovarian cancer tissue samples

We investigated the BRCA1 gene copy number in unselected ovarian malignancies. Both additional genes (amplification) as well as deletion (loss of heterozygosity, LOH) are often thought to have a role in the initiation or progression of cancer. In addition, if there were little change, deletion studies might help identify BRCA1 mutation carriers. Forty-seven paraffin-embedded ovarian tissue blocks obtained between 1984 and 1997 were used for this study. A sample was "deletion-positive" when BRCA1-deleted cells in the tumor area were significantly different from the benign area. Twenty-five (53%) cases were found to be "deletion-positive". The average age of onset of "deletion-positive" patients was 50.8 years and of "deletion-negative" 57.8 years (P < 0.05). There was no statistical difference between groups in the staging, histology, or prognosis. A Kaplan-Meier study did show a trend towards poorer survival for "deletion-positive" patients. FISH permits unique molecular characterization of malignancies at a cellular level. Double amplification of HER-2 and c-myc predicts poor ovarian cancer survival. There appears to be a definite role for BRCA1 deletion in reducing the age of ovarian cancer onset and possibly in overall survival. Further FISH studies of this and other patient sets using additional molecular markers are needed.

Peritoneal carcinoma in women with genetic susceptibility: implications for Jewish populations

Women from families with multiple cases of breast and ovarian cancer, specifically those who carry cancer-associated mutations of BRCA1 or BRCA2 are at increased life-time risk for peritoneal carcinoma, even after previous surgery to remove the ovaries, fallopian tubes and uterus. Hereditary breast-ovarian cancer (HBOC) syndrome and the associated BRCA1 and BRCA2 mutations are particularly prevalent in women of Jewish lineage, and specific BRCA1 and BRCA2 germline mutations have been linked with peritoneal carcinoma and HBOC syndrome in Jewish populations, especially those of Ashkenazi descent. This review presents the currently available data and looks forward toward further and better understanding of peritoneal carcinoma in women with inherited susceptibility. Over 90% of peritoneal cancer in patients from HBOC syndrome kindreds and associated with BRCA1 and BRCA2 mutations are serous carcinomas, which is equivalent with the proportion of ovarian cancers that are serous carcinomas in similar patients. The best indications are that while many peritoneal carcinomas in genetically susceptible women may arise directly from malignant transformation of the peritoneum, others might represent metastases from primary ovarian or fallopian tube carcinomas. Although the incidence of borderline ovarian tumors may not be increased in HBOC syndrome kindreds and those who carry cancer-associated BRCA1 and BRCA2 mutations, these individuals could be susceptible to malignant transformation of borderline lesions of the ovaries and peritoneum. Moreover, recent reports raise the question of possibly increased risk in Jewish carriers of germline BRCA1 mutations for uterine papillary serous carcinoma, which could be the source of metastasis to the peritoneum in some cases. The penetrance of cancer-associated BRCA1 mutations for ovarian cancer is estimated to be 11%-54%, and for BRCA2 mutations the penetrance for ovarian cancer is 11%-23%. So far, available screening methods appear to be insufficient for early detection of many ovarian cancers. Prophylactic oophorectomy has been found to reduce the risk for ovarian cancer in women from HBOC kindreds and those who carry cancer-associated BRCA1 and BRCA2 mutations, leaving a residual risk for peritoneal carcinomatosis of well less than 5%. Therefore, surgical removal of the ovaries, fallopian tubes and uterus, after child-bearing has been completed and by early in the fifth decade of life, are appropriate prophylactic procedures in women whose genetic susceptibility puts them at increased risk for cancers of mullerian tract origin, including ovarian and fallopian tube carcinomas and possibly serous carcinoma of the uterus. Hysterectomy, as well as salpingo-oophorectomy, removes the gynecologic organs targeted for malignant transformation in genetically susceptible women and simplifies decisions regarding hormone replacement therapy and chemical prophylaxis and treatment of breast cancer. Unless a transabdominal operative approach is otherwise indicated, laparoscopic-assisted transvaginal techniques are well suited for intra-abdominal exploration, cytology, biopsies and prophylactic salpingo-oophorectomy and hysterectomy in women with hereditary susceptibility to gynecologic cancer.

Genetic analysis of benign ovarian tumors

Ovarian cancer represents a major cause of cancer death among women and yet remarkably little is known about its etiology. The paradigm established by the colorectal carcinogenesis model would suggest that ovarian cancers are likely to arise through malignant transformation of benign ovarian tumors. However, molecular genetic data that could answer this important question is lacking. In our study, we analyzed 80 benign ovarian tumors for TP53 and K-ras mutations and for LOH on chromosomes 6, 7, 9, 11 and 17 using 56 microsatellite markers. Twenty-five percent (5/20) of non-epithelial tumors and 73% (44/60) of epithelial tumors exhibited LOH on at least 1 chromosome arm. A particularly high frequency of LOH was detected among the epithelial tumors on chromosome arms 6q (17%), 7p (17%), 7q (27%) and 11p (18%), which are also regions of frequent LOH among ovarian carcinomas. No K-ras mutations were detected in any tumor but somatic TP53 mutations were detected in 2/34 (6%) serous and 1/26 (4%) mucinous epithelial tumors. In contrast to most previous studies our data is derived from a relatively large number of microdissected tumors and is likely to represent a more accurate picture of the frequency of alterations in these tumors. We conclude that LOH is common in benign ovarian tumors, suggesting that inactivation of tumor suppressor genes are pivotal in their development. The high frequency of alterations is consistent with their being precursors to malignant disease but does not unequivocally prove this continuum. It does however provide a framework for future analysis of the molecular genetic etiology of ovarian tumorigenesis.

Molecular genetic evidence for monoclonal origin of bilateral ovarian serous borderline tumors

Patients with serous borderline tumors of the ovary often present with multiple tumors at different sites in the abdominal cavity. Whether different foci of ovarian serous borderline tumors are monoclonal in origin, arising as a consequence of spread from a single ovarian site, or whether such deposits are polyclonal and explained by independent molecular genetic alterations on the background of a field defect, is unknown. So far, only X-chromosome inactivation studies were performed to study this issue. We used a genome-wide allelotyping to assess clonality in 47 metachronous and/or synchronous multifocal tumors from 22 patients, using 59 microsatellite markers. Loss of heterozygosity (LOH) was observed in only 34 of 1969 informative markers in 9 of 22 serous borderline cases studied. Of these cases, 7 showed concordant LOH for at least one polymorphic marker in more than one tumor site. Flanking microsatellite markers enabled identification of identical chromosomal breakpoints in 6 of 7 cases. The LOH results strongly favor a common origin indicated by a likelihood ratio (possibility common origin/possibility independent origin) ranging from 39 to 14,163. Strong additional evidence for monoclonality is provided by the finding of identical microsatellite alterations in all three-tumor sites in one case.

TP53 and ovarian cancer

Ovarian cancer represents the fourth most frequent type of cancer among females and is the leading cause of death from gynecological cancer in the western world. This review describes gene alterations in ovarian cancer. Specific emphasis is placed on genetic alterations and the prevalence of TP53 (p53) gene alterations in the distinct biological ovarian tumors (benign, borderline, and malignant) and histological subtypes (serous, mucinous, endometrioid, clear cell), as well as in BRCA1-associated hereditary ovarian cancer. Although multi-modality treatment regimens, including cytoreductive surgery and cisplatin-containing combination chemotherapy, have usefully prolonged survival, the overall cure rate of the disease has not changed dramatically. Ovarian cancer is difficult to eradicate completely by surgery and many patients have only a partial response to postoperative chemotherapy and/or many will develop chemotherapy resistance. All these important factors contribute to the poor prognosis of ovarian cancer patients. In this review, the putative prognostic or predictive value of TP53 in ovarian cancer is addressed.

Muscarinic receptors in cell lines from ovarian carcinoma: negative correlation with survival of patients

OBJECTIVES

Tumor cells are similar in many respects to embryonic cells, indicating that embryonic genes are reactivated during malignant growth. In previous studies, we observed muscarinic acetylcholine receptors, which are expressed in embryonic cells during morphogenesis and are also found in human melanomas and melanoma cell lines. We determined the presence of muscarinic receptors in a collection of ovarian tumor cell lines for which clinical data were available.

METHODS

Muscarinic receptor status of 39 cell lines derived from 34 patients was determined by Western blotting.

RESULTS

Twenty-three cell lines were receptor positive, and 16, receptor negative. Kaplan-Meier analysis of receptor status of the tumor cell lines and survival time of patients from which the cell lines were established showed that expression of muscarinic receptors was associated with a reduced probability (P = 0.025) of survival: This is within the range of other established prognostic factors reported in the literature.

CONCLUSIONS

A large percentage of ovarian tumor cell lines express muscarinic receptors. Muscarinic receptor expression is an embryonic trait and is correlated with reduced survival of patients. The results from this study provide further evidence of the involvement of muscarinic receptors in the progression of malignant carcinomas.

Activins and inhibins in endocrine and other tumors

Inhibin and activin are members of the TGF beta superfamily of growth and differentiation factors. They were first identified as gonadal-derived regulators of pituitary FSH and were subsequently assigned multiple actions in a wide range of tissues. More recently, the inhibin alpha subunit was considered as a tumor suppressor based on functional studies employing transgenic mouse models. This review evaluates the functional and molecular evidence that the inhibin alpha subunit is a tumor suppressor in endocrine cancers. The evaluation highlights the discrepant results from the human and mouse studies, as well as the differences between endocrine tumor types. In addition, we examine the evidence that the activin-signaling pathway is tumor suppressive and identify organ-specific differences in the actions and putative roles of this pathway in endocrine tumors. In summary, there is a considerable body of evidence to support the role of inhibins and activins in endocrine-related tumors. Future studies will define the mechanisms by which inhibins and activins contribute to the process of initiation, promotion, or progression of endocrine-related cancers.

Allelic imbalance is not restricted to numerically abnormal chromosomes in epithelial ovarian tumours

In this study, 23 low malignant potential (LMP) and 27 invasive epithelial ovarian tumours have been examined by microdissection and microsatellite polymerase chain reaction (PCR) for allelic imbalance (AI) at loci on the p and q arms of chromosomes 1, 11, 17, and X, and the data have been compared with interphase cytogenetics for numerical abnormalities (aneusomy) of these chromosomes. AI was uncommon in LMP tumours (5 of 23 at 9 of 146 informative loci) but was significantly more common (p<0.001) in invasive carcinomas (21 of 27 at 47 of 168 informative loci). This difference remained when LMP tumours were compared specifically with stage I carcinomas (p<0.001). A greater number of loci were involved in AI amongst serous than amongst mucinous carcinomas (p=0.015). AI was present at significantly more loci in carcinomas showing aneusomy by interphase cytogenetics than in those showing no numerical chromosome abnormalities (p<0.001). However, amongst the carcinomas showing aneusomy, AI was as frequent at loci on chromosomes with no numerical abnormality as at those with the numerical changes. These data demonstrate that aneusomy and AI are interrelated phenomena but that AI does not occur simply as a consequence of numerical chromosome changes.

Chromosome 7 monosomy and deletions in myeloproliferative diseases

We studied deletion and monosomy of chromosome 7 in 150 patients with myeloproliferative diseases. We found 8/150 patients with monosomy 7 by cytogenetics and 4/150 with deletions of the long arm of chromosome 7 by restriction fragment length polymorphism (RFLP) analysis performed with Southern and polymerase chain reaction. To overcome limitation of RFLP analysis, we restricted loss of heterozygosity study with microsatellites to 45 patients, observing deletion 7q31.1 in 7/45 patients. In all patients with molecular alterations the deletion was observed only in myeloid cells, while the monosomy was detected in both myeloid precursor and lymphocytes. This finding suggests a CD34-totipotent stem cell origin for the monosomy and a colony forming unit - granulocyte, erythrocyte, monocyte, megakaryocytes (CFU-GEMM) stem cell origin for the deletions.

Localization of a susceptibility gene for familial nonmedullary thyroid carcinoma to chromosome 2q21

The familial form of nonmedullary thyroid carcinoma (NMTC) is a complex genetic disorder characterized by multifocal neoplasia and a higher degree of aggressiveness than its sporadic counterpart. In a large Tasmanian pedigree (Tas1) with recurrence of papillary thyroid carcinoma (PTC), the most common form of NMTC, an extensive genomewide scan revealed a common haplotype on chromosome 2q21 in seven of the eight patients with PTC. To verify the significance of the 2q21 locus, we performed linkage analysis in an independent sample set of 80 pedigrees, yielding a multipoint heterogeneity LOD score (HLOD) of 3.07 (alpha=0.42), nonparametric linkage (NPL) 3.19, (P=.001) at marker D2S2271. Stratification based on the presence of at least one case of the follicular variant of PTC, the phenotype observed in the Tas1 family, identified 17 such pedigrees, yielding a maximal HLOD score of 4.17 (alpha=0.80) and NPL=4.99 (P=.00002) at markers AFMa272zg9 and D2S2271, respectively. These results indicate the existence of a susceptibility locus for familial NMTC on chromosome 2q21.

Detection of loss of heterozygosity at chromosome 3p25-26 in primary and metastatic ovarian clear-cell carcinoma: utilization of microdissection and polymerase chain reaction in archival tissues

Loss of heterozygosity (LOH) at the 3p region is found in up to 50% of epithelial ovarian neoplasms. The von Hippel-Lindau (VHL) gene at the 3p25 locus is one of the tumor-suppressor genes located at 3p. The role, if any, of the VHL gene locus is not clear in ovarian carcinogenesis. We analyzed primary and metastatic ovarian clear-cell carcinomas (OCCC) for LOH at 3p25 to determine its frequency and its diagnostic utility as an adjunctive tool in the differential diagnosis of metastatic clear-cell carcinomas. Microdissection followed by single-step DNA extraction and polymerase chain reaction (PCR) amplification, using two polymorphic markers flanking the VHL gene locus, was done on archival histology and cytology samples from 9 patients with metastatic OCCC. Of the informative cases, 43% of the metastatic and 50% of the primary OCCC showed LOH. LOH at the VHL gene locus is not uncommon in clear-cell ovarian carcinoma. LOH at 3p25 in cytologic specimens may be a valuable adjunct in the diagnosis of OCCC metastasis in cytologically equivocal cases. OCCC should enter the differential in clear-cell carcinomas of unknown primary that show LOH at 3p25. Published 2001 Wiley-Liss, Inc.

Multiple chromosomal underrepresentations detected by interphase cytogenetics - possible prognostic markers in head and neck tumors?

Relevant prognostic factors for head and neck squamous cell carcinoma are tumor extension (pT), occurrence of lymph node metastases (pN) and grade of differentiation (G). We tried to correlate these histological characteristics with numerical aberrations of whole chromosomes as demonstrated by fluorescence in situ hybridization techniques (FISH). Therefore, we investigated isolated interphase cells from paraffin sections of squamous cell carcinomas of the head and neck region from 46 patients with centromeric DNA probes for chromosomes 1, 3, 4, 6, 7, 9, 10, 11, 12, 15, 17, 18, X and Y. The majority of tumor samples showed aneuploidy for most chromosomes analyzed. The main chromosomal abnormality was loss of chromosomal material, predominantly of chromosomes 3 (28%), 6 (20%), 9 (26%), 10 (24%) and 18 (33%). Multiple deletions could be demonstrated more frequently in poorly differentiated carcinomas (88% G3-tumors with more than one deletion in contrast to 66% G2-tumors). The occurrence of multiple deletions may also correlate with progression in lymph node metastasis (66% in pN0-tumors vs. 85% in pN2-tumors), whereas the differences between the stages of primary tumor extension were not so obvious. Despite of a some-what disproportionate distribution of tumors in the different pT- and pN-stages and the rather low number of cases, our results suggest a relationship between the quantity of chromosomal underrepresentation, grade of differentiation and higher lymph node stage. Therefore, they underline the importance of chromosomal deletions as a possible additional prognostic marker in head and neck squamous cell carcinoma.

Histology of prophylactically removed ovaries from BRCA1 and BRCA2 mutation carriers compared with noncarriers in hereditary breast ovarian cancer syndrome kindreds

OBJECTIVE

The literature reports conflicting studies claiming premalignant histological features in benign ovaries from women who may have hereditary predilections for ovarian carcinoma. To test the veracity of these claims, this investigation studied ovaries prophylactically removed from members of hereditary breast ovarian cancer (HBOC) syndrome families who carry BRCA1 and BRCA2 mutations and compared these with the ovaries of mutation-negative women from the same HBOC syndrome kindred.

METHODS

Sixty cases of women from HBOC syndrome families who had undergone prophylactic oophorectomies and whose BRCA1 and BRCA2 mutation status had been tested were selected from our database. Thirty had tested positive for BRCA1 mutations, 3 carried BRCA2 mutations, and 27 were negative for both BRCA1 and BRCA2 germline mutations. Histologic material from each case was examined by light microscopy blinded to the mutation status. Histologic features, previously reported to be possible precursor lesions for ovarian cancer, were quantified. Data from BRCA1 and BRCA2 mutation carriers were compared with those from mutation-negative cases in the direct line of genetic inheritance from the same HBOC syndrome families.

RESULTS

Statistical analysis found that a more frequent occurrence of ovarian surface micropapillae in 87% of mutation carriers compared with just 55% of mutation-negative cases was the only histologic feature which was significantly different between the two groups (P = 0.39). Cortical clefts tended to be deeper in the ovaries of mutation carriers, but this did not reach significance (P = 0.051). There were no other significant histologic differences between the ovaries removed from mutation carriers and those from noncarriers.

CONCLUSIONS

The results of our large and prospectively controlled, blinded study contrast with those reported from smaller, unblinded investigations. Except for the possible biological significance of surface micropapillae on ovaries from BRCA1 and BRCA2 mutation carriers, we found no histologic evidence for a genetically determined ovarian carcinoma precursor lesion.

Loss of heterozygosity on 10q and microsatellite instability in advanced stages of primary cutaneous T-cell lymphoma and possible association with homozygous deletion of PTEN

Previous cytogenetic studies of primary cutaneous T-cell lymphoma (CTCL) were based on limited numbers of patients and seldom showed consistent nonrandom chromosomal abnormalities. In this study, 54 tumor DNA samples from patients with CTCL were analyzed for loss of heterozygosity on 10q. Allelic loss was identified in 10 samples, all of which were from the 44 patients with mycosis fungoides (10/44 patients; 23%). Of the patients with allelic loss, 3 were among the 29 patients with early-stage myosis fungoides (T1 or T2) (3/29 patients; 10%), whereas the other 7 were among the 15 patients with advanced cutaneous disease (T3 or T4) (7/15 patients; 47%). The overlapping region of deletion was between 10q23 and 10q24. In addition, microsatellite instability (MSI) was present in 13 of the 54 samples (24%), 12 from patients with mycosis fungoides and 1 from a patient with Sezary syndrome. There was also an association between MSI and disease progression in patients with mycosis fungoides, with 6 of 15 (40%) patients with MSI having advanced cutaneous disease and only 6 of 29 (21%) having early-stage disease. Samples with allelic loss on 10q were analyzed for abnormalities of the tumor suppressor genePTEN (10q23.3). No tumor-specific mutations were detected, but homozygous deletion was found in 2 patients. Thus, we found loss of heterozygosity on 10q and MSI in advanced cutaneous stages of mycosis fungoides. These findings indicate that a tumor suppressor gene or genes in this region may be associated with disease progression. Furthermore, abnormalities of PTEN may be important in the pathogenesis of mycosis fungoides, but our data imply that this gene is rarely inactivated by small deletions or point mutations.

Ovarian serous borderline tumors: a critical review of the literature with emphasis on prognostic indicators

BACKGROUND

The behavior of ovarian serous borderline tumors (SBTs) and significance of various prognostic factors are unclear and difficult to evaluate because of inconsistencies and confusion in the literature. Recent studies have suggested that the morphological features of the primary tumor (presence or absence of micropapillary features) and the peritoneal "implants" (presence or absence of invasive features) can reliably subclassify SBTs into benign and malignant types. The aim of the current review was to test two hypotheses. First, that the alleged malignant behavior of SBTs is poorly documented, and second, that the morphological features of the primary ovarian tumors and the associated peritoneal implants are sufficient to separate SBTs into benign and malignant types, thereby obviating the need for the category.

METHODS

245 studies reporting approximately 18,000 patients with borderline ovarian tumors were reviewed. After excluding series that lacked clinical follow-up or were not analyzable for other reasons, there remained 97 reports that included 4,129 patients. In addition to recurrences and survival, we evaluated the type of peritoneal implants, microinvasion, lymph node involvement, late recurrences, and progression to carcinoma, as these features have served as the underpinning of the concept of "borderline malignancy" or "low malignant potential."

RESULTS

Among 4,129 patients with SBTs reviewed, the recurrence rate after a mean follow-up of 6.7 years was 0.27% per year for stage I tumors, the disease-free survival was 98.2%, and the overall disease-specific survival rate was 99.5%. For patients with advanced-stage tumors, the recurrence rate was 2.4% per year. However, the majority (69%) of reported recurrences were not pathologically documented, and only 26 cases (8.4% of all recurrences) were documented to have recurred from an adequately sampled ovarian tumor. The most reliable prognostic indicator for advanced stage tumors was the type of peritoneal implant. After 7.4 years of follow-up, the survival of patients with noninvasive peritoneal inplants was 95.3%, as compared with 66% for invasive implants (P < .0001). Microinvasion in the primary ovarian tumor was associated with a 100% survival rate at 6.7 years, and lymph node involvement was associated with a 98% survival rate at 6.5 years. The few reported cases of stage IV disease, progression to invasive carcinoma, and very late (>20 years) recurrences were poorly documented. The survival for all stages among approximately 373 patients in 6 prospective randomized trials followed for a mean of 6.7 years was 100%.

CONCLUSION

Surgical pathological stage and subclassification of extraovarian disease into invasive and noninvasive implants are the most important prognostic indicators for SBTs. Survival for stage I tumors is virtually 100%. Survival for advanced stage tumors with noninvasive implants is 95.3%, whereas survival for tumors with invasive implants is 66%. Invasive implants behave as carcinomas and are most likely metastatic. The precise nature of so-called noninvasive implants is not clear, but they behave in a benign fashion. The presence of a micropapillary architecture in the primary ovarian tumor is a strong predictor of invasive implants. These data support the recommendation that ovarian tumors with a micropapillary architecture be designated "micropapillary serous carcinomas," and those lacking these features, "atypical proliferative serous tumors."

Loss of heterozygosity in P53, BRCA1, and estrogen receptor genes and correlation to expression of p53 protein in ovarian epithelial tumors of different cell types and biological behavior

Loss of heterozygosity (LOH) of tumor suppressor genes (TSGs) in ovarian epithelial tumors of differing cell types and biological behavior has not been thoroughly investigated. Moreover, there have been conflicting reports correlating LOH of the p53 gene to overexpression of p53 protein. This study evaluated 34 formalin-fixed, paraffin-embedded ovarian epithelial tumors for LOH by polymerase chain reaction (PCR) for the following microsatellite markers: TP53(17p13.1/p53 gene), D17S579(17q/BRCA1 gene), and ESR (6q24-27/estrogen receptor gene). LOH of the TP53 marker was detected in 4 (44%) of 9 informative serous cystadenocarcinomas (SCa) but in 0 of 4 informative clear cell carcinomas (CCa) and 0 of 5 informative serous tumors of low malignant potential (SLMP). LOH of the BRCA1 marker was detected in 5 (83%) of 6 informative SCa, but in 1 (13%) of 8 informative CCa and 1 (14%) of 7 informative SLMP. LOH of the ESR marker was detected in 4 (50%) of 8 informative SCa, but in 0 of 4 informative CCa and 1 (16%) of 6 informative SLMP. p53 protein overexpression was present in 8 of 12 SCa but did not correlate to TP53 LOH. LOH for TP53, D17S579/ BRCA1, and ESR is common in ovarian SCa, and is observed in primary tumors as well as metastases. In contrast, these genetic alterations are less common in CCa and in the biologically less aggressive SLMP tumors. These data suggest different mechanisms of oncogenesis in ovarian epithelial tumors of different cell types and biological behavior.

Somatic mutations of the PPP2R1B candidate tumor suppressor gene at chromosome 11q23 are infrequent in ovarian carcinomas

Previous studies have demonstrated frequent allelic losses of distal chromosome 11q in ovarian carcinomas. The tumor suppressor gene(s) presumably targeted by these losses have not yet been identified. PPP2R1B is a candidate tumor suppressor gene at 11q23 that has recently been shown to be mutated in a subset of colorectal and lung cancers. We evaluated 5 ovarian carcinoma cell lines and 27 primary ovarian carcinomas for allelic losses of 11q23 and for mutations in the open reading frame of PPP2R1B. We also evaluated the primary tumors for allelic losses at 17p13, another chromosomal region frequently affected by losses of heterozygosity (LOH) in ovarian cancers. 11q23 and 17p13 allelic losses were identified in 25% and 74% of the carcinomas, respectively. No mutations within PPP2R1B coding sequences were found. These findings indicate that mutations of the PPP2R1B gene are infrequent in ovarian cancer and that deletions affecting the distal portion of chromosome 11q in ovarian cancer likely target inactivation of other genes.

Is TP53 dysfunction required for BRCA1-associated carcinogenesis?

The identification of the breast/ovarian susceptibility genes, BRCA1 and BRCA2 was an important advancement in the field of breast and ovarian cancer research. About 40-50% of site specific hereditary breast cancers and up to 80% of hereditary breast-ovarian cancers result from mutations in the BRCA1 gene. Although BRCA1 mediates multiple functions in the cell, including a role in DNA damage repair and gene transcription, the role of BRCA1 has not completely been elucidated yet. It has been suggested that mutational inactivation of TP53 may be required for BRCA1-associated tumorigenesis. Several studies have shown that TP53 is more frequently inactivated in BRCA1-associated tumors than in sporadic breast or ovarian cancer. Up to 90% of BRCA1-associated tumors harbor either a TP53 mutation and/or TP53 protein accumulation. The remaining tumors may well have other alterations affecting the cell cycle checkpoint. Loss of this checkpoint may be obligatory for BRCA1-tumorigenesis. In this review, we discuss recent advances in BRCA1-research and stress the pivotal role TP53 may play in BRCA1-associated carcinogenesis.

Allelic loss on chromosome arm 8p: analysis of sporadic epithelial ovarian tumors

OBJECTIVE

Our objective was to determine the frequency of allelic loss at 8p21 in sporadic epithelial ovarian cancer. We recently described allelic loss at this locus in 7/9 ovarian cancers from patients with BRCA1 gene mutations.

METHODS

We anonymously obtained and examined 40 unselected invasive epithelial ovarian cancers and 5 low-malignant-potential (LMP) ovarian tumors for loss of heterozygosity (LOH) at 8p12-22. Pure epithelial and stromal cell populations were procured selectively by laser capture microdissection and extracted DNA was amplified with polymorphic microsatellite markers spanning the region of interest.

RESULTS

LOH was highest (50%) at marker D8S136 located at 8p21 with 15 of 30 informative cases exhibiting an allelic deletion. None of the LMP tumors evaluated showed LOH at 8p12-22. A trend toward more frequent LOH at 8p12-22 was identified with increasing disease aggressiveness from LMP to early stage invasive ovarian cancer to advanced stage invasive ovarian cancer (Lehman's test, P2 < 0.024).

CONCLUSIONS

Fifty percent allelic loss at the distal portion of 8p21 has not been reported to date for sporadic epithelial ovarian carcinomas. The higher rate of loss in our cohort, in contrast to previous allelotyping studies, is due likely to analysis from homogenous cell populations. These results, in concert with our previous study of BRCA1 mutation-positive patients, suggest a tumor suppressor gene locus at 8p21 for epithelial ovarian cancer.