Analysis of oncogene alterations in human endometrial carcinoma: prevalence of ras mutations

Ornithine decarboxylase as a therapeutic target for endometrial cancer

Ornithine Decarboxylase (ODC) a key enzyme in polyamine biosynthesis is often overexpressed in cancers and contributes to polyamine-induced cell proliferation. We noted ubiquitous expression of ODC1 in our published endometrial cancer gene array data and confirmed this in the cancer genome atlas (TCGA) with highest expression in non-endometrioid, high grade, and copy number high cancers, which have the worst clinical outcomes. ODC1 expression was associated with worse overall survival and increased recurrence in three endometrial cancer gene expression datasets. Importantly, we confirmed these findings using quantitative real-time polymerase chain reaction (qRT-PCR) in a validation cohort of 60 endometrial cancers and found that endometrial cancers with elevated ODC1 had significantly shorter recurrence-free intervals (KM log-rank p = 0.0312, Wald test p = 5.59e-05). Difluoromethylornithine (DFMO) a specific inhibitor of ODC significantly reduced cell proliferation, cell viability, and colony formation in cell line models derived from undifferentiated, endometrioid, serous, carcinosarcoma (mixed mesodermal tumor; MMT) and clear cell endometrial cancers. DFMO also significantly reduced human endometrial cancer ACI-98 tumor burden in mice compared to controls (p = 0.0023). ODC-regulated polyamines (putrescine [Put] and/or spermidine [Spd]) known activators of cell proliferation were strongly decreased in response to DFMO, in both tumor tissue ([Put] (p = 0.0006), [Spd] (p<0.0001)) and blood plasma ([Put] (p<0.0001), [Spd] (p = 0.0049)) of treated mice. Our study indicates that some endometrial cancers appear particularly sensitive to DFMO and that the polyamine pathway in endometrial cancers in general and specifically those most likely to suffer adverse clinical outcomes could be targeted for effective treatment, chemoprevention or chemoprevention of recurrence.

The genomics and genetics of endometrial cancer

Most sporadic endometrial cancers (ECs) can be histologically classified as endometrioid, serous, or clear cell. Each histotype has a distinct natural history, clinical behavior, and genetic etiology. Endometrioid ECs have an overall favorable prognosis. They are typified by high frequency genomic alterations affecting PIK3CA, PIK3R1, PTEN, KRAS, FGFR2, ARID1A (BAF250a), and CTNNB1 (β-catenin), as well as epigenetic silencing of MLH1 resulting in microsatellite instability. Serous and clear cell ECs are clinically aggressive tumors that are rare at presentation but account for a disproportionate fraction of all endometrial cancer deaths. Serous ECs tend to be aneuploid and are typified by frequent genomic alterations affecting TP53 (p53), PPP2R1A, HER-2/ERBB2, PIK3CA, and PTEN; additionally, they display dysregulation of E-cadherin, p16, cyclin E, and BAF250a. The genetic etiology of clear cell ECs resembles that of serous ECs, but it remains relatively poorly defined. A detailed discussion of the characteristic patterns of genomic alterations that distinguish the three major histotypes of endometrial cancer is reviewed herein.

Syndecan-1, a key regulator of cell viability in endometrial cancer

Syndecan-1 is one of the major proteoglycans on cell surfaces involved in major biological processes. Although loss of syndecan-1 correlates well with the gain of cancerous characteristics in a wide range of cancers, increased expression of syndecan-1 also coincides with adverse outcomes in some cancers, including breast, ovarian and pancreatic cancers. For this Janus-faced attitude of syndecan-1, we sought to examine expression patterns of syndecan-1 in endometrial carcinoma (EC) and gain insight into the roles of syndecan-1. Immunohistochemical examinations of 109 endometrial tissue samples from myoma, hyperplasia and EC uteri revealed that syndecan-1 expression was significantly upregulated in EC compared with hyperplasia (p < 0.001). To evaluate pathophysiological functions of syndecan-1, its expression level was altered, and subsequent outcomes were examined using human endometrial cancer cell lines such as HEC-1A, AN3CA and KLE cells. Overexpression of syndecan-1 increased the growth of HEC-1A cells regardless of anchorage dependence while silencing syndecan-1 by antisense RNAs caused apoptotic cell death. Consistent with decreased viability, the loss of syndecan-1 was also accompanied by a decrease in the activation of Erk and Akt and a concomitant decrease in the phosphorylation of PTEN and PDK1, which are known as negative and positive regulators of Akt activation, respectively. These down-regulatory effects were reversed upon overexpression of syndecan-1. Collectively together, the aforementioned findings lend support to the notion that upregulation of syndecan-1 may be a critical element for endometrial cancers in maintaining their viability and thus can serve as a cancer specific therapeutic and diagnostic marker.

TRAIL mediates apoptosis in cancerous but not normal primary cultured cells of the human reproductive tract

Cancer of the reproductive tract encompasses malignancies of the uterine corpus, cervix, ovary, Fallopian tube, among others and accounts for 15% of female cancer mortalities. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) mediates apoptosis by binding to death receptors and offers a promising cancer treatment. The goal of this study was to investigate and characterize the effect of TRAIL in endometrial cancer cell lines and normal (non-cancerous) epithelial cells of endometrial origin. We also examined the effect of TRAIL in other primary cultured cancers and normal cells of the human female reproductive tract and evaluated if TRAIL mediated apoptosis correlated with death receptors and decoy receptors 1 and 2.Herein, we demonstrate that TRAIL at concentrations which kill cancerous cells, does not mediate apoptosis or alter cell viability in normal human endometrium, ovary, cervix or Fallopian tube. The partial inhibition by a caspase 9 inhibitor and the total inhibition by a caspase 8 inhibitor demonstrates the dependency on the extrinsic apoptotic pathway. The selective mortality does not correlate with the presence of death or decoy receptors. These results suggest that TRAIL may be an effective treatment for endometrial cancer and other female reproductive cancers, with minimal secondary effects on healthy tissue.

Ten-year results of a prospective study on the prognostic role of ploidy in endometrial carcinoma

BACKGROUND

To improve the outcome of endometrial cancer patients, a more accurate prognostic assessment is mandatory. The aims of the study were to evaluate the role of flow cytometric DNA ploidy as an independent prognostic factor in patients with endometrial cancer and to verify if ploidy was able to distinguish patients with different prognosis into homogeneous subgroups for grade of differentiation and stage.

METHODS

In a prospective study, DNA ploidy was evaluated from fresh tumor samples in 174 endometrial cancer patients who underwent surgery as the first treatment. Ploidy, as well as classical parameters, were analyzed in relation to the length of disease-free survival and disease-specific survival.

RESULTS

DNA aneuploidy was found in 49 patients (28.2%). Patients with DNA-aneuploid tumors had a significantly reduced disease-free interval and disease-specific survival (P < .0001). The 10-year survival probability was 53.2% for DNA-aneuploid patients and 91.0% for patients with DNA-diploid tumors. By multivariate analysis DNA-aneuploid type was the strongest independent predictor of poor outcome, followed by age and stage. Patients with DNA-aneuploid tumor had a significantly higher risk ratio for recurrence (5.03) and death due to disease (6.50) than patients with DNA-diploid tumors. Stratification by DNA-ploidy within each group by grade of differentiation allowed identification of patients with significantly different outcome. In grade 2 tumors, 10-year survival was 45.0% in aneuploid cases and 91.9% in diploid cases (P < .0001). Patients with advanced-stage (>I) diploid tumor did significantly better than patients with stage I aneuploid tumor (P = .04).

CONCLUSIONS

The presence of DNA-aneuploid type in endometrial cancer identifies high-risk cases among the patients considered 'low risk' according to stage and grade of differentiation.

Molecular pathogenesis and prognostic factors in endometrial carcinoma

Endometrial carcinoma is today among the most common gynecologic malignancies in industrialized countries. In order to improve the treatment and follow-up of these patients, various prognostic factors have been extensively studied. Patient age, stage of disease, histologic type and histologic grade have been shown to influence survival significantly, and the prognostic impact of these traditional clinicopathologic variables is well established. In addition, parity, hormone receptor concentration in the tumor, DNA ploidy and morphometric nuclear grade have all been found to influence prognosis. Information about DNA ploidy has especially been used in the clinical situation to determine individualized treatment. The prognostic significance of markers for tumor cell proliferation, cell cycle regulation (p53, p21 and p16) and angiogenesis is discussed as well as the molecular basis of endometrial carcinoma. In conclusion, several prognostic markers have been identified. It is likely that the information derived from these tumor biomarkers will reduce the need for extensive surgical staging and adjuvant treatment in endometrial carcinoma.

HEC-1 cells

HEC-1 cell line was the first in vitro cell line of a human endometrial adenocarcinoma which enabled us to perform research work on the endometrium and endometrial carcinoma at a simplified cellular system, contributing cell and molecular biological studies on endometrial carcinoma. Once a cell line is established, it provides a stable experimental system that facilitates and progresses in the study of the tissues and/or neoplasias from which they are derived. In this article we report how HEC-1 cells have been established and cleared the proposed requirements to characterize the established cell line. Also to show the usefulness of the cell line for research work, once it was established, we illustrate these concepts by recalling results obtained with HEC-1 cells and reviewing the literature on what has been achieved by using these cells.

Overexpression of mitogen-activated protein kinase superfamily proteins unrelated to Ras and AF-1 of estrogen receptor alpha mutation in advanced stage human breast cancer

Transactivation of the activation function-1 (AF-1) region of the estrogen receptor alpha (ER-alpha) gene is regulated by pathway "cross-talk" from Ras mitogen-activated protein kinase (MAPK). An analysis of this system is important for solving the problem of resistance to anti-estrogen agents used in the treatment of human breast cancer. We investigated the ER-alpha and Ras gene mutations and the MAPK-related protein status in 103 cases of breast carcinoma. None of the cases showed mutations in the AF-1 region of the ER-alpha gene. Despite the extremely low frequency of K- and H-Ras mutations in codon 12 (2/103 and 0/103), Ras p21 overexpression was identified in 29.1% (30/103), suggesting that the Ras activation in almost all cases we studied was not caused by point mutations but by enhanced expression. Our immunohistochemical analysis showed that the cases with overexpression of Ras and MAPK proteins (Ras p21, ERK-1, JNK-1, and p38) had a progressive tendency towards invasive growth, advanced-stage cancer, and decreased levels of ER-alpha protein. These results suggest that enhanced MAPK activity could be one of the characteristics of advanced breast cancer and that it could be involved in the transformation into estrogen-independent growth.

Expression of c-kit (CD117) in benign and malignant human endometrial epithelium

BACKGROUND

The proto-oncogene c-kit encodes a tyrosine kinase receptor (CD117) with a molecular weight of 145 kd. Previous studies, predominantly utilizing immunohistochemistry, have led to contradictory findings regarding the expression of CD117 in the endometrium. To help resolve this issue, we analyzed a series of benign and malignant endometrial tissues using both immunohistochemistry and Western blot analysis.

OBJECTIVE

To examine the expression of CD117 in benign and malignant human endometrial tissues.

METHODS

The expression of CD117 in 35 benign endometrial tissues (7 hyperplastic, 14 proliferative, 14 secretory) and 10 endometrioid carcinomas was investigated by immunohistochemistry (clone K45 monoclonal antibody). Immunoprecipitation (clone K69 monoclonal antibody) followed by Western blotting (clone K45 monoclonal antibody and clone 1.D9.3D6 monoclonal antibody) was performed to confirm CD117 expression.

RESULTS

Fifty-seven percent of the hyperplasias, 93% of proliferative endometria, and 79% of secretory endometria immunostained positively for CD117. In benign endometria, epithelial staining tended to be more intense in the hyperplastic and proliferative endometria as compared to the secretory endometria, whereas endometrial stromal cells were not immunoreactive. Of the 10 frozen endometrial tissues analyzed by immunohistochemistry, 4 of 9 endometrioid carcinomas and a single case of an endometrioid polyp developing in association with a carcinoma expressed CD117. Immunoprecipitation followed by Western blot analysis confirmed expression of full-length CD117 in an endometrial polyp and carcinoma, and revealed a correlation between levels of immunoprecipitated CD117 and immunohistochemical staining intensity.

CONCLUSIONS

Benign and malignant endometrial tissues express CD117. Our data suggest (a) a possible relationship between estrogen and CD117 expression in benign endometrium and (b) potential involvement of this growth factor receptor in endometrial carcinogenesis.

Theories of endometrial carcinogenesis: a multidisciplinary approach

Historical observations have suggested that endometrial carcinomas vary in histopathologic appearance and clinical features. More recent, systematic studies have provided epidemiologic, clinicopathologic, and molecular support for these observations. Specifically, studies suggest that the most common type of endometrial carcinoma, endometrioid adenocarcinoma, develops from endometrial hyperplasia in the setting of excess estrogen exposure and usually pursues an indolent clinical course. In contrast, a minority of endometrial carcinomas, best represented by serous carcinoma, do not seem to be related to estrogenic risk factors or elevated serum hormone levels, and these tumors seem to develop from atrophic rather than hyperplastic epithelium. We have proposed that serous carcinomas develop from "endometrial intraepithelial carcinoma," a lesion representing malignant transformation of the endometrial surface epithelium. Whereas endometrioid carcinoma and endometrial hyperplasia are associated with microsatellite instability and ras and PTEN mutations, serous carcinoma and endometrial intraepithelial carcinoma are associated with p53 mutations and abnormal accumulation of p53 protein. Based on these data regarding the pathogenesis of endometrioid and serous carcinoma, we have proposed a dualistic model of endometrial carcinogenesis incorporating a "classic" estrogen-driven pathway and an "alternative" pathway seemingly unrelated to hormones. It is hoped that further studies may permit the extension and modification of this model and that these advances will lead to improved diagnosis, management, and prevention.

Predominant p53 G-->A transition mutation and enhanced cell proliferation in uterine sarcomas of CBA mice treated with 1,2-dimethylhydrazine

Mouse uterine tumors were examined for genetic alterations in the ras proto-oncogene and p53 tumor suppressor gene and for other biologically relevant immunohistochemical markers that may increase our understanding of the events that occur in uterine cancer. Fourteen dimethylhydrazine (DMH)-induced uterine sarcomas, including 3 primary malignant fibrous histiocytomas (MFH), 7 transplanted MFH, 3 stromal sarcomas, and 1 undifferentiated sarcoma, were first screened by immunohistochemistry for p53 missense mutations, followed by single strand conformation polymorphism analysis and DNA sequencing for the identification of point mutations. There was 100% correlation between p53 protein immunopositivity and subsequent detection of p53 mutations in DMH-induced malignant fibrous histiocytomas. All MFH had a characteristic p53 G:C-->A:T transition mutation, consistent with O6-methylguanine mispairing with thymine, the most common DNA lesion caused by alkylating agents. DMH-induced uterine MFH with p53 mutations also had a higher proliferative rate (qualitatively evaluated by immunohistochemical detection of proliferating cell nuclear antigen) when compared with other DMH-induced sarcomas. Uterine sarcomas were further evaluated for biological end points, such as estrogen receptor and desmin. Neoplastic cells from stromal sarcomas (SS), undifferentiated sarcomas (US), and MFH did not stain for desmin. The estrogen receptor was detected in normal uteri and a small portion of MFH, SS, and US. Our data suggest that DMH-induced uterine sarcomas are not consistent with smooth muscle cell origin and that a subset of these tumors, specifically DMH-induced malignant fibrous histiocytomas, have unique p53 G:C-->A:T transitions and a high proliferative rate.

Oncogenic Ras modulates epidermal growth factor responsiveness in endometrial carcinomas

Since the majority of endometrial carcinomas do not contain any detectable ras mutations, the precise contribution of aberrant Ras function, if any, to endometrial carcinoma development remains to be determined. Since there is considerable evidence that Ras transformation is associated with a decreased requirement for growth factors, we compared the growth response of endometrial carcinoma cells harbouring wild-type (Ishikawa cells) or mutated (HHUA cells) K-ras to epidermal growth factor (EGF). K-ras mutation did not significantly affect the level of the EGF receptor (EGFR) expressed in these carcinoma cells. EGF could stimulate the growth of Ishikawa, but not HHUA cells. Furthermore, EGF caused elevation of Ras-GTP levels in Ishikawa, but not HHUA cells. However, the introduction of mutated, but not normal, K-ras into Ishikawa cells rendered them non-responsive to EGF growth stimulation. Thus, the presence of mutated K-ras alone modulated the growth response of endometrial carcinoma cells to EGF. An inhibitor of the EGFR tyrosine kinase activity could prevent soft agar colony formation of Ishikawa cells, but not HHUA or mutant K-ras(12V)-transfected Ishikawa cells. Taken together, these results suggest that mutated K-ras causes a loss of responsiveness to EGF stimulation and that EGFR function is dispensable for the growth of mutant Ras-positive endometrial carcinoma cells.

Relationship of nonstaging pathological risk factors to lymph node metastasis and recurrence in clinical stage I endometrial carcinoma

OBJECTIVE

To determine if DNA ploidy, hormone receptors, vascular space invasion (VSI), perivascular lymphocytes (PVL), and the oncogenes HER-2/neu, p53, and bcl-2 are independent prognostic indicators for lymph node metastasis and cancer recurrence in clinical stage I endometrial carcinoma.

METHODS

Among 349 patients with clinical stage I endometrial cancer 31 patients either had lymph node metastases when surgically staged or developed recurrent cancer. Using a case-control matched-pair technique, controls were selected for each of 24 cases by matching for age, histological grade, depth of myometrial invasion, performance of node dissection, and use of adjuvant radiation therapy. In a blinded fashion a pathologist reviewed all histopathology, and all molecular tests were performed on paraffin-embedded tissue samples. Statistical analysis was performed by chi2 and McNemar's tests.

RESULTS

VSI was the only histopathological factor significantly related to positive lymph nodes and cancer recurrence (P = 0.01), independent of grade and myometrial invasion. Aneuploidy, oncogene expression (p53, HER-2/neu, bcl-2), and hormone receptors were not significantly related to lymph node metastasis and cancer recurrence.

CONCLUSIONS

The presence of vascular space invasion is a pathological factor independently associated with a risk of nodal metastasis and cancer recurrence in clinical stage I endometrial cancer. DNA ploidy, oncogene expression, and hormone receptor status do not have more predictive value than standard staging pathological criteria.

The clinicopathological significance of K-RAS point mutation and gene amplification in endometrial cancer

The aim of this study was to examine the prevalence and clinicopathological significance of K-RAS oncogene activation in endometrial carcinoma and atypical hyperplasia. We analysed K-RAS point mutation and gene amplification in 55 endometrial carcinomas using polymerase chain reaction associated with restriction fragment length polymorphism and genomic differential polymerase chain reaction. Point mutations at codon 12 of K-RAS oncogene were identified in 8 of 55 (14.5%) tumour specimens. In addition, we were unable to detect any K-RAS gene amplification in any of the endometrial carcinomas studied. No correlation was found between K-RAS gene mutation and age at onset, histological subtype, grade of differentiation, clinical stage or current patient status. We conclude that K-RAS mutation is a relatively common event in endometrial carcinomas, but with no clear prognostic value.

Loss of heterozygosity in usual and special variant carcinomas of the endometrium

Endometrial carcinoma is the most common invasive malignancy of the female genital tract, and it exists as two different clinicopathologic forms: an estrogen-dependent, "usual" type and an estrogen-independent "special variant" type. Despite the frequency of endometrial cancer, little is known about the molecular genetic events that contribute to its pathogenesis. The accumulation of genetic alterations identified through the study of loss of heterozygosity (LOH), gene mutation, and gene activation in tumor DNA has been associated with the establishment and progression of a variety of human malignancies. A relatively low incidence of LOH has been reported in usual type endometrial cancers; however, special variant tumors have rarely been included in the reported studies. To understand the molecular events that contribute to both forms of endometrial cancer, 31 tumors have been surveyed for events of LOH on all chromosomes. The study groups included 18 tumors of the usual type and 13 special variant tumors. Polymorphic loci were studied by Southern blot analysis and polymerase chain reaction (PCR) of microsatellite loci. Normal tissue in each case served as a control. Both frequency and patterns of LOH differed greatly between the two tumor types. Although LOH was frequently detected in the special variant tumors, it was rare in the usual type tumors. LOH was detected in only 8 of the 18 usual tumors, with chromosomes 17, 13, and 2 being the most frequently affected (22%, 20%, and 19%, respectively). In contrast, LOH was detected in all cases of special variant tumors, with chromosomes 17p, 14, and 12 showing the highest LOH (83%, 77%, and 40%, respectively). Two cases of microsatellite instability (MI) were detected among the usual type tumors. These findings suggest that the clinicopathologic phenotypes observed in these tumor types are likely caused by different tumorigenic pathways that reflect alterations of different cancer-controlling genes.

Aberrant FGF-2, FGF-3, FGF-4 and C-erb-B2 gene copy number in human ovarian, breast and endometrial tumours

The important role of oncogene amplification and tumour suppressor gene deletion in human tumours is becoming increasingly apparent. However, extensive screening of human tumours is required before the prognostic significance of such genetic abnormalities can be fully appreciated. The present investigation describes a rapid non-radioactive and largely automated procedure for the analysis of aberrant gene copy number in large numbers of tissue samples of different human tumours. This procedure is based on the sequential use of the polymerase chain reaction (PCR) and high performance ion exchange liquid chromatography (HPIEX). Using this rapid PCR/HPIEX technique, we have identified amplification and deletion of the FGF-2 gene and the FGF-3, FGF-4 and c-erb-B2 oncogenes in human tumours of the breast, ovary and endometrium. Comparison of the data with tumour pathology has revealed possible associations between aberrant gene copy number and tumour type, invasiveness and metastases.

Regulation of microfilament organization and anchorage-independent growth by tropomyosin 1

Variants of chemically immortalized Syrian hamster embryo cells that had either retained (supB+) or lost (supB-) the ability to suppress tumorigenicity when hybridized with a fibrosarcoma cell line were subcloned. Both supB cell types are nontumorigenic; however, the supB- but not supB+ cells exhibit conditional anchorage-independent growth. Alterations of actin microfilament organization were observed in supB- but not supB+ cells that corresponded to a significant reduction of the actin-binding protein tropomyosin 1 (TM-1) in subB- cells. To examine the possibility of a direct relationship between TM-1 expression and the subB- phenotype, subB+ cells were transfected with an expression vector containing the TM-1 cDNA in an antisense orientation. The antisense-induced reduction of TM-1 levels in supB+ clones caused a microfilament reorganization and conferred anchorage-independent growth potential that were indistinguishable from those characteristic of supB- cells. These data provide direct evidence that TM-1 regulates both microfilament organization and anchorage-independent growth and suggest that microfilament alterations are sufficient for anchorage-independent growth.

Molecular basis of endometrial cancer

BACKGROUND

Most human cancers are thought to arise from alterations in oncogenes and tumor suppressor genes.

METHODS

Molecular techniques have been used to identify specific genetic alterations in endometrial cancers.

RESULTS

Overexpression of the HER-2/neu oncogene occurs in 10% of endometrial cancers and correlates with poor survival. Alterations in other receptor tyrosine kinases (c-fms and epidermal growth factor receptor) also occur in some cases. The c-myc oncogene, which encodes a nuclear transcription factor, also may be overexpressed in some invasive cancers. Mutations in the K-ras oncogene occur in 10% and in 20-30% of American and Japanese endometrial cancers, respectively. K-ras mutations also have been observed in endometrial hyperplasias, and this may represent an early event in the development of some cancers. Mutation of the p53 tumor suppressor gene, with resultant overexpression of mutant p53 protein, occurs in 20% of endometrial adenocarcinomas. Overexpression of p53 is associated with advanced stage and poor survival. Because p53 mutations do not occur frequently in endometrial hyperplasias, this may be a relatively late event in endometrial carcinogenesis. Recent studies have shown that mutations occur in microsatellite sequences in some endometrial cancers. Because microsatellite instability in hereditary nonpolyposis colon cancer has been found to be caused by mutations in DNA repair genes, similar mutations are being sought in endometrial cancers.

CONCLUSIONS

Although several molecular alterations have been identified, the molecular pathogenesis of endometrial cancer remains poorly understood.

p53 in endometrial cancer and its putative precursors: evidence for diverse pathways of tumorigenesis

To elucidate the role of p53 abnormalities in endometrial tumorigenesis, a diverse group of endometrial neoplasms and their putative precursors, atypical endometrial hyperplasia, and endometrial intraepithelial carcinoma (EIC) were studied using a conventional immunohistochemical technique. Immunostaining for p53 protein was detected in 24 (86%) of 28 serous carcinomas compared with nine (20%) of 45 endometrioid carcinomas (P < .001). Immunoreactivity was also detected in two (100%) of two clear cell carcinomas, five (83%) of six mixed endometrioid/serous carcinomas, and seven (70%) of 10 malignant mixed mesodermal tumors. Benign endometrial tissue and 12 examples of atypical endometrial hyperplasia were nonreactive. In 27 (79%) of 34 tumors containing EIC, both the tumor and EIC were immunoreactive for p53, whereas in 7 (21%) both were negative. Immunostaining for p53 highlighted small foci of EIC and showed the extent and distribution of the lesions. The strong association and similar p53 immunostaining pattern of EIC and serous carcinoma support the hypothesis that serous carcinomas develop from endometrial surface epithelium that demonstrates abnormal p53 protein expression in conjunction with transformation to EIC. Mutation of p53 seems unrelated to the development of endometrioid carcinoma from atypical endometrial hyperplasia but may be related to dedifferentiation in some of these neoplasms.

Human endometrial carcinoma cells release factors which inhibit the growth of normal epithelial cells in culture

Autocrine and paracrine interactions between cells are important homeostatic mediators in normal tissues. Alterations to growth factor signalling pathways are likely to play a role in multistep carcinogenesis. In this study normal human endometrial epithelial cells (NHEC) after 3 days in culture were treated with serum-free medium conditioned for 24 h by log phase or confluent cultures of established RL95-2, HEC1A, or AN3CA endometrial carcinoma (EC) cell lines. By day 4, NHEC treated with either log phase or confluent conditioned medium (CM) showed a significant decrease (approximately 50-90% of control) in [3H]thymidine ([3H]TdR) incorporation. DNA synthesis was inhibited more by confluent than by log phase CM. By day 7, NHEC treated with CM exhibited fewer colonies per culture, fewer cells per colony, and an increased percentage of single cells. Several growth-regulatory gene products found in the nucleus or at the cell membrane have been shown to be expressed differently in normal and transformed cells. We selected the p53 and c-Ha-ras p21 proteins to further investigate the mechanism of alteration of proliferation in cells treated with carcinoma CM. Thus, by day 7, the percentage of NHEC with nuclear localization of wild type p53 (wt p53) was elevated by treatment with CM. In contrast, CM-treated EC cells continued to proliferate, and showed a decrease in the percentage of cells expressing nuclear wt p53 and an increase in the cytoplasmic expression of c-Ha-ras p21. Our studies show that EC cell lines release factors which inhibit the proliferation of NHEC, thus favoring the proliferation of EC cells.

Expression and mutation analysis of the p53 gene in uterine papillary serous carcinoma

BACKGROUND

The status of p53 protein expression was determined by immunohistochemistry and correlated with genetic analysis and clinical outcome in patients with uterine papillary serous carcinoma (UPSC).

METHODS

Twenty-two patients with UPSC were identified and immunohistochemical staining of p53 protein was performed. Staining was analyzed by quantitating nuclear reactivity in 500 randomly counted cells per specimen. DNA analysis was performed on the tumors using single-strand conformation polymorphism (SSCP) analysis of exons 4-10 of the p53 gene, followed by DNA sequencing of all variants. Clinical data and patient status were ascertained from chart reviews.

RESULTS

Sixteen of the 22 (73%) tumors were scored as p53-overexpressing as determined by immunohistochemical analysis. Patients whose tumors overexpressed p53 had a statistically significant shorter survival than those whose tumors did not (P < 0.022). DNA analysis of the 22 tumors revealed five with mutations of the p53 gene. Only three of these mutations were observed in tumors that overexpressed p53.

CONCLUSIONS

A relatively large percentage of UPSC tumors exhibited high p53 immunoreactivity. Overexpression is correlated with poor prognosis. Positive immunohistochemistry for p53 protein in UPSC is not necessarily indicative of a genetic mutation.

Biomarkers in the endometrium

A number of oncogenes and tumor suppressor genes that may serves as surrogate biomarkers of transformation are altered during the process of endometrial carcinogenesis. Overexpression of HER-2/neu occurs in 10% of endometrial adenocarcinomas and correlates with intraperitoneal spread of disease and poor survival. The c-myc oncogene is amplified in 10% of cases. Point mutations in codon 12 of the K-ras oncogene have been reported to occur in 10-20% of endometrial cancers. K-ras mutations also have been noted in some endometrial hyperplasias, which may represent an early event in the development of some endometrial cancers. Mutation of the p53 tumor suppressor gene, with resultant overexpression of mutant p53 protein, occurs in 20% of endometrial adenocarcinomas. Overexpression of p53 is associated with advanced stage and poor survival. Because p53 mutations have not been observed in endometrial hyperplasias, this is thought to be a relatively late event in endometrial carcinogenesis. Microsatellite instability has also been noted in approximately 15% of sporadic endometrial cancers, but mutations in DNA repair genes have not yet been reported. Chemoprevention trials in endometrial cancer may be feasible due to the existence of a premalignant lesion and surrogate biomarkers.

Endometrial cancer chemoprevention: implications of diverse pathways of carcinogenesis

Endometrial cancers may be divided into two groups, reflecting differences in clinical behavior and pathogenesis. Endometrioid adenocarcinoma, which accounts for the majority of endometrial cancers, typifies the group of endometrial carcinomas that develop from atypical endometrial hyperplasia in the setting of excess estrogenic stimulation. In contrast, serous carcinomas are representative of endometrial tumors that occur in older women who have endometrial atrophy and lack the typical endometrial cancer risk factors reflecting unopposed estrogen exposure. Serous carcinomas are frequently associated with p53 abnormalities and appear to develop from a surface lesion termed endometrial intraepithelial carcinoma. Although serous carcinomas are rare, these highly aggressive tumors account for a disproportionate number of endometrial cancer deaths. Further delineation of the estrogen-dependent and estrogen-independent pathways of endometrial carcinogenesis may be useful in developing comprehensive chemopreventive approaches for endometrial cancer.

Estrogen resistance caused by a mutation in the estrogen-receptor gene in a man

BACKGROUND AND METHODS

Mutations in the estrogen-receptor gene have been thought to be lethal. A 28-year-old man whose estrogen resistance was caused by a disruptive mutation in the estrogen-receptor gene underwent studies of pituitary-gonadal function and bone density and received transdermal estrogen for six months. Estrogen-receptor DNA, extracted from lymphocytes, was evaluated by analysis of single-strand-conformation polymorphisms and by direct sequencing.

RESULTS

The patient was tall (204 cm [80.3 in.]) and had incomplete epiphyseal closure, with a history of continued linear growth into adulthood despite otherwise normal pubertal development. He was normally masculinized and had bilateral axillary acanthosis nigricans. Serum estradiol and estrone concentrations were elevated, and serum testosterone concentrations were normal. Serum follicle-stimulating hormone and luteinizing hormone concentrations were increased. Glucose tolerance was impaired, and hyperinsulinemia was present. The bone mineral density of the lumbar spine was 0.745 g per square centimeter, 3.1 SD below the mean for age-matched normal women; there was biochemical evidence of increased bone turnover. The patient had no detectable response to estrogen administration, despite a 10-fold increase in the serum free estradiol concentration. Conformation analysis of his estrogen-receptor gene revealed a variant banding pattern in exon 2. Direct sequencing of exon 2 revealed a cytosine-to-thymine transition at codon 157 of both alleles, resulting in a premature stop codon. The patient's parents were heterozygous carriers of this mutation, and pedigree analysis revealed consanguinity.

CONCLUSIONS

Disruption of the estrogen receptor in humans need not be lethal. Estrogen is important for bone maturation and mineralization in men as well as women.

Cytogenetic analysis of murine cell lines from diethylstilbestrol-induced uterine endometrial adenocarcinomas

Treatment of female CD-1 mice with the synthetic estrogen diethylstilbestrol (DES) on days 1 through 5 after birth results in a 90% incidence of endometrial adenocarcinomas by 18 months of age Three cell lines were established from DES-induced uterine carcinomas and studied for specific chromosomal changes. Each cell line exhibited numerical decreases in chromosomes 9, 11, 13, and X as common abnormalities. Structural alterations involving chromosomes 3, 6, 11, and 19 occurred nonrandomly among the three cell lines. Every cell line showed a rearrangement in the long arm of chromosome 3 (3q+), a translocation between chromosomes 3 and 19 [t(3;19)], isochromosome of chromosome 11 [i(11)], and a marker chromosome (M2) either as common abnormalities or recurrent abnormalities. t(3;19), i(11), and M2 were observed also in the primary colonies from which the cell lines arose. The changes were not observed in a cell line derived from the uterus of one untreated control mouse, suggesting that these chromosomal alterations may have occurred during DES-induced neoplastic transformation. The chromosomal alterations found in the present study may prove useful in investigating the genetic changes involved in DES carcinogenesis.

Observations on tumor and metastatic suppressor gene status in endometrial carcinoma with particular emphasis on p53

BACKGROUND

Genetic changes in the development of endometrial carcinoma have not been characterized, and little is known of tumor or metastatic suppressor gene status in these malignancies. The current study on endometrioid carcinoma was undertaken to examine the status of two tumor suppressor genes that frequently have been found to be altered in human malignancies (the p53 gene and the retinoblastoma [Rb] gene) and to examine the status of the candidate metastatic suppressor gene, nm23-H1.

METHODS

The status of the p53 gene was studied by immunohistochemistry of formalin-fixed paraffin-embedded biopsy samples from 72 patients with atypical endometrial hyperplasia or endometrioid carcinoma who underwent hysterectomy immediately after biopsy and from 5 patients with benign endometria. A search for loss of heterozygosity (LOH) of the nm23 gene after DNA extraction from frozen tissues and hybridization with nm23-H1 cDNA specific probe was made in 10 endometrial carcinomas. Rb gene status was evaluated by image analysis quantification of immunoreactive retinoblastoma protein in frozen sections of 10 carcinomas and 2 benign endometria.

RESULTS

p53 expression was low in all benign endometria, but high expression was found in 2 (15%) of 13 atypical hyperplasias and in 23 (39%) of 59 carcinomas. High levels of p53 expression in endometrioid carcinoma correlated with the spread of disease outside of the uterus and by logistic regression, the presence of squamous differentiation, nuclear grade, and high p53 expression in the biopsy all independently correlated with spread of disease outside of the uterus. Although 7 of the 10 carcinomas studied were informative, LOH for the nm23 gene was not seen in any, including a site of metastasis. Rb protein expression in endometrial carcinoma was similar to expression in benign endometria.

CONCLUSIONS

Although this study found no evidence of nm23-H1 gene alteration or alterations in Rb protein levels in endometrial carcinoma, high expression of p53 protein was sporadically identified in biopsy specimens of atypical hyperplasia and frequently found in endometrioid carcinomas. Determination of p53 expression in combination with the presence or absence of squamous differentiation and nuclear grade in biopsy material may help predict spread of endometrioid carcinoma outside the uterus and facilitate therapeutic planning before hysterectomy.

Low incidence of c-Ha-ras gene mutations in benign and malignant cutaneous lesions from transplant recipients

Transplant recipients successively develop benign, premalignant and malignant skin lesions on sun-exposed areas. It has been suggested that UV radiations might induce mutations in ras oncogenes and p53 tumour-suppressor gene, responsible for skin cancers. With PCR and oligoprobe hybridization, we investigated c-Ha-ras gene mutations at codons 12 and 61 in 120 cutaneous lesions from grafted patients, since they could represent a marker of the evolution of benign skin lesions towards malignancy in this population; 29 similar skin biopsies from non-immunosuppressed patients were also analyzed. In transplant recipients, we detected mutations at codon 12 only in 1/42 non-melanoma skin cancers and 2/29 pre-cancerous keratoses. No mutation was detected in 11 cases of cutaneous Bowen's disease from grafted patients and in pre-malignant and malignant skin samples from control patients. Benign warts exhibited an overall incidence of 18% and 15% of mutations at codon 12 of c-Ha-ras gene in grafted and control patients respectively. We detected only one mutation at codon 61 in a plantar wart. Human papillomaviruses (HPV) are thought to be involved in the malignant evolution of cutaneous disorders in transplant recipients and cooperate with a ras oncogene to induce malignancy in vitro. The presence of HPV DNA in our series of skin samples from grafted patients showed no correlation with the occurrence of c-Ha-ras mutations. Our findings indicate that c-Ha-ras-gene activation by mutations is rare in cutaneous lesions from transplant recipients, and is unlikely to play a crucial role in transformation towards malignancy in skin carcinogenesis among grafted patients.

Activities of antioxidant enzymes and lipid peroxidation in endometrial cancer

Antioxidant enzyme activities and lipid peroxidation were analysed in normal endometrium and endometrial cancer tissues from Finnish and Japanese patients. The catalase and glutathione peroxidase activities of normal endometrium were significantly lower in Finns than in Japanese. Lipid peroxidation was slightly higher in endometrial cancer as compared with normal endometrium both in the Finns and in the Japanese. When cancer tissues were compared with normal endometrium both in Finns and Japanese the activity of superoxide dismutase was significantly lower in cancer tissue than in normal endometrium. In Finns glutathione S-transferase activity was also lower in endometrial cancer tissue than in normal endometrium, and a similar tendency was also found in Japanese. This study suggests that endometrial cancer tissue is associated with an impaired enzymic antioxidant defence system.

Alterations of the Rb gene and its association with Ki-ras activation and p53 inactivation in endometrial adenocarcinoma

Alterations of the retinoblastoma (Rb) gene were evaluated in nine primary endometrial adenocarcinomas that we had previously analyzed for the presence of Ki-ras activations and p53 alterations and in three endometrial carcinoma cell lines. Loss of mRNA expression in the Rb gene was detected in two of the 12 tumors. Internal deletions of Rb cDNA were observed in two tumors; one was a deletion of exon 21 in a primary carcinoma, and the other was a deletion of exon 8 in one allele in one cell line. Loss of heterozygosity of the Rb gene, which was detectable by polymorphisms in introns 1 and 17, was analyzed using polymerase chain reaction-restriction fragment length polymorphism analysis in 29 endometrial carcinomas. Of 13 heterozygous cases, two cases (15%) showed loss of heterozygosity. We therefore suggest that alteration of the Rb gene, as well as activation of the Ki-ras gene and alterations of the p53 gene, plays a significant role in the etiology of endometrial adenocarcinoma.

Proto-oncogene erbA expression and increased abundance of progesterone receptors in the mouse uterus after passive immunisation against progesterone before implantation

Passive immunisation with a monoclonal anti-progesterone antibody (DB3) prevents pregnancy in the mouse, and antibody is localised in the endometrium before the onset of implantation. BALB/c female mice were injected intraperitoneally with 9 nmol of DB3 (a dose known to cause 100% infertility) 32 h post coitum, and the uterus was removed at various times after injection. Using a monoclonal anti-progesterone receptor antibody (PR6), expression of progesterone receptors was found to be abundant in uterine tissue of DB3-treated mice; this was associated with substantial progesterone receptor mRNA levels and with maximum localisation of DB3 antibody as detected by anti-idiotype antibody. Control animals treated with an equal amount of the mouse myeloma protein P3 showed very low levels of progesterone receptor in the uterus. DB3 treatment also affected uterine expression of the proto-oncogene erbA product (which shows primary sequence homology with the progesterone receptor) as revealed by specific antiserum to the ERBA protein and by in situ hybridisation with a cDNA probe to v-erbA. Time-course studies indicated that the erbA gene was expressed at a high level before progesterone receptor expression increased, that its expression was dependent on the presence of the embryo and that erbA expression persisted longer in DB3-treated females. The observations suggest that anti-progesterone immunisation has a direct effect within the uterus, involving persistence of proto-oncogene erbA expression (which itself may represent an early maternal response to pregnancy) and increased progesterone receptor levels resulting from an unopposed oestrogen effect derived from local ligand withdrawal.

Mutations of the Ki-ras oncogene in endometrial carcinoma

OBJECTIVE

The purpose of this study was to assess the extent of involvement of the ras oncogene in endometrial carcinoma.

STUDY DESIGN

Genomic deoxyribonucleic acid from 30 samples of endometrial carcinoma was examined for point mutations in codons 12, 13, and 61 from the Ha-ras, Ki-ras, and N-ras genes by means of the polymerase chain reaction, slot-blotting, and deoxyribonucleic acid sequencing procedures.

RESULTS

An apparent somatic mutation of Ki-ras codon 12 in one of 10 paraffin-embedded tumors was confirmed by deoxyribonucleic acid sequence analysis. Two of 20 frozen endometrial carcinoma specimens were also shown to contain a point mutation in Ki-ras codon 12. No correlation between ras mutation and a number of histologic or clinical parameters was observed.

CONCLUSIONS

These data suggest a potential role for Ki-ras codon 12 mutations in the development of some (10%) endometrial cancers.

Characterization of murine cell lines from diethylstilbestrol-induced uterine endometrial adenocarcinomas

Neonatal treatment with estrogens is associated with development of uterine adenocarcinomas in CD-1 mice. Treatment with the synthetic estrogen diethylstilbestrol (DES) on Days 1 to 5 after birth results in 90% incidence of these hormone-dependent lesions in 18-mo.-old mice. Three cell lines were established from these DES-associated tumors. Each of these cell lines exhibited morphologic and ultrastructural characteristics of transformed epithelial cells, including an increased nuclear:cytoplasmic ratio, enlarged and irregular nuclei with multiple nucleoli and areas of chromatin condensation, positive staining for cytokeratin, desmosomes, and microvilli. After subcutaneous injection into nude mice, all three cell lines formed solid tumors within 4 wk. Although the primary uterine tumors and tumor transplants in nude mice had been shown to be estrogen-dependent and estrogen-receptor positive, neither the monolayer growth nor the tumorigenicity of any of the three cell lines in this study was enhanced by or dependent on estrogen. Estrogen receptor levels were low in early and intermediate passage cells. Allele-specific oligonucleotide hybridization analysis of PCR-amplified cell line DNA revealed no point mutations in the 12th, 13th, or 61st codons of the K-ras or H-ras protooncogenes. Southern analysis revealed no changes in genomic organization of the putative tumor suppressor gene DCC, but demonstrated a three- to four-fold amplification of the c-myc gene in one cell line. Expression of c-myc RNA was concomitantly increased in the same cell line. These three transformed cell lines represent the end point in the process of hormone-associated tumorigenesis and as such should prove useful in investigating the molecular changes and the mechanisms involved in hormonal carcinogenesis.

p53 gene mutations in human endometrial carcinoma

Although carcinoma of the uterine endometrium is the most frequently diagnosed malignancy of the female reproductive tract, the molecular genetic features of this tumor have yet to be described in significant detail. Since mutations of the p53 tumor suppressor gene are the single most common genetic alteration found in human malignancies, we examined the hypothesis that p53 mutations occur in human endometrial carcinoma. Sequencing analysis of exons 5-8 revealed point mutations in 3 of 21 (14%) tumors; one mutation was an unusual single-base insertion at codons 176-177, resulting in a premature stop codon, whereas the other two were CGG----TGG transitions at codon 248. Two of these tumors showed reduction to homozygosity at the p53 allele, but one tumor apparently retained heterozygosity. These data indicate that p53 mutations occur in human endometrial carcinoma, although relatively infrequently, and that loss of the normal p53 allele does not necessarily occur with point mutation of the p53 gene in this tumor type.