Expression of cell-cycle regulatory proteins in endometrial carcinomas: correlations with hormone receptor status and clinicopathologic parameters

Effect of active vitamin D on proliferation, cell cycle and apoptosis in endometriotic stromal cells

RESEARCH QUESTION

What is the effect of vitamin D3 (1,25(OH)₂D₃) on proliferation, cell cycle and apoptosis of endometrial stromal cells (ESC) in endometriotic patients?

DESIGN

ESC isolated from 10 women with endometriosis and 10 healthy controls were treated with 1,25(OH)₂D₃. The proliferation of control endometrial stromal cells (CESC), eutopic endometrial stromal cells (EuESC) and ectopic endometrial stromal cells (EESC) was analysed 72 h after the treatment using methyl thiazolyl tetrazolium assay. Propidium iodide staining and flow cytometry were used to determine the cell cycle distribution in ESC. Annexin V/propidium iodide double staining was used to evaluate apoptosis in ESC.

RESULTS

In the presence of oestrogen, 1,25(OH)₂D₃ treatment inhibited the proliferation of ESC from all three origins (P = 0.009 for CESC, P = 0.005 for EuESC and P < 0.001 for EESC). The percentage of S phase cells in EESC was higher than in EuESC and CESC (P = 0.002 and P = 0.001, respectively). The percentage of S phase cells in EuESC was higher than in CESC (P = 0.005). The percentage of G1 phase cells in EESC was lower than that of EuESC and CESC (P = 0.003 and P = 0.002, respectively) and the percentage of G1 phase cells in EuESC was lower than that of CESC (P = 0.007). Moreover, 1,25(OH)₂D₃ inhibited cell cycle regardless of cell type (P = 0.002 in EESC, P = 0.001 in EuESC and P = 0.014 in CESC), but in the absence of oestrogen, inhibited cell cycle only in EuESC (P = 0.012).

CONCLUSIONS

Although 1,25(OH)₂D₃ increased apoptotic and necrotic cells and decreased live cells in the EuESC and EESC, it did not affect apoptosis in CESC and only increased necrotic cells. These findings indicate that 1,25(OH)₂D₃ potentially has a growth-inhibiting and pro-apoptotic effect on ESC from endometriotic patients.

Role of Nucleolin in Endometrial Precancerous Hyperplasia and Carcinogenesis: Ex Vivo and In Silico Study

Endometrial cancer (EC) is the most common gynaecological malignancy. Nucleolin (NCL) is involved in rDNA transcription, cell proliferation, and apoptosis, with high expression associated with worse overall survival (OS) in other adenocarcinomas. Our aims were to assess NCL gene and protein expression and explore the differential expression of NCL-associated genes (NAGs) in endometrial carcinogenesis. Endometrial samples were obtained from 157 women to include healthy, hyperplastic (EH), EC, and metastatic groups. RT-qPCR and immunohistochemistry were employed to assess NCL gene and protein levels. In silico analysis of NAGs in TCGA and GEO datasets was performed, with the prognostic value determined via Human Protein Atlas. NCL mRNA level of EC was lower than in healthy post-menopausal endometrium (p < 0.01). EH samples had lower NCL immuno-expression scores than healthy pre-menopausal (p < 0.001), benign post-menopausal (p < 0.01), and EC (p < 0.0001) samples. Metastatic lesions demonstrated higher NCL quick scores than primary tissue (p = 0.04). Higher NCL Immuno quick scores carried a worse OS in high-grade EC (p = 0.01). Interrogating Uterine Corpus Endometrial Carcinoma (TCGA-UCEC) and Uterine Carcinosarcoma (TCGA-UCS) cohorts revealed NCL to be the most highly upregulated gene in carcinosarcoma, with S100A11, LMNB2, RERG, E2F1 and CCNA2 representing key dysregulated NAGs in EC. Since NCL is implicated in transforming hyperplastic glands into cancer, with further involvement in metastasis, it is suggested to be a promising target for better-informed diagnosis, risk stratification, and management of EC.

Clinicopathologic and protein markers distinguishing the “polymerase epsilon exonuclease” from the “copy number low” subtype of endometrial cancer

Objective

The need to perform genetic sequencing to diagnose the polymerase epsilon exonuclease (POLE) subtype of endometrial cancer (EC) hinders the adoption of molecular classification. We investigated clinicopathologic and protein markers that distinguish the POLE from the copy number (CN)-low subtype in EC.

Methods

Ninety-one samples (15 POLE, 76 CN-low) were selected from The Cancer Genome Atlas EC dataset. Clinicopathologic and normalized reverse phase protein array expression data were analyzed for associations with the subtypes. A logistic model including selected markers was constructed by stepwise selection using area under the curve (AUC) from 5-fold cross-validation (CV). The selected markers were validated using immunohistochemistry (IHC) in a separate cohort.

Results

Body mass index (BMI) and tumor grade were significantly associated with the POLE subtype. With BMI and tumor grade as covariates, 5 proteins were associated with the EC subtypes. The stepwise selection method identified BMI, cyclin B1, caspase 8, and X-box binding protein 1 (XBP1) as markers distinguishing the POLE from the CN-low subtype. The mean of CV AUC, sensitivity, specificity, and balanced accuracy of the selected model were 0.97, 0.91, 0.87, and 0.89, respectively. IHC validation showed that cyclin B1 expression was significantly higher in the POLE than in the CN-low subtype and receiver operating characteristic curve of cyclin B1 expression in IHC revealed AUC of 0.683.

Conclusion

BMI and expression of cyclin B1, caspase 8, and XBP1 are candidate markers distinguishing the POLE from the CN-low subtype. Cyclin B1 IHC may replace POLE sequencing in molecular classification of EC.

Body mass index and cyclin B1, caspase 8, and X-box binding protein 1 are candidate markers distinguishing between the polymerase epsilon exonuclease (POLE) and copy number (CN)-low subtypes of endometrial cancer. Cyclin B1 immunohistochemistry expression was significantly higher in the POLE than in the CN-low subtype and may substitute POLE sequencing.

The extent of cyclin D1 expression in endometrial pathologies and relevance of cyclin D1 with the clinicopathological features of endometrioid endometrial carcinoma

Background

Cyclin D1, a member of the cyclin protein family, is instrumental in the cell cycle due to its influence on the progression from G1 to the S phase. Its overexpression causes reduced doubling time and is also associated with clonogenic growth. The purpose of the present study was to assess cyclin D1 expression in patients with simple hyperplasia (SH), endometrial intraepithelial neoplasia (EIN) and endometrioid endometrial carcinoma, and to evaluate whether there was an association between cyclin D1 expression and the clinicopathological features of endometrioid endometrial carcinoma.

Methods

Retrospective data were available for 193 patients (30 SH, 40 EIN, and 123 endometrioid endometrial carcinoma cases). To detect cyclin D1 expression, immunohistochemistry staining was performed with tissue microarrays.

Results

The percentage of cases with positive cyclin D1 staining were 30%, 60% and 78%, for SH, EIN and endometrioid endometrial carcinoma, respectively (P < 0.001). Carcinomas with higher nuclear grade, histological grade, and FIGO grade displayed higher mean cyclin D1 expression compared to lower grade carcinomas. In addition, patients with lymphovascular invasion (P = 0.006), myometrial invasion (P < 0.001) and lymph node invasion (P < 0.001) had higher mean cyclin D1 expression compared to those without invasion. There was a significant correlation between cyclin D1 expression and clinicopathological features of endometrioid endometrial carcinoma including tumor grade, FIGO grade, lymphovascular invasion, lymph node invasion and myometrial invasion (P < 0.05 for each).

Conclusion

Cyclin D1 expression is significantly higher in patients with endometrioid endometrial carcinoma compared to that of the SH and EIN. The extent of cyclin D1 expression is strongly correlated with nuclear and histological grade, myometrial invasion, lymphovascular invasion and lymph node invasion in patients with endometrioid endometrial carcinoma. These findings contribute in several ways to our understanding of cyclin D1 expression and provide a basis for future research on this topic.

Role of Cyclin-Dependent Kinase Inhibitors in Endometrial Cancer

Endometrial Cancer (EC) is an important cause of death in women worldwide. Despite early diagnosis and optimal treatment of localized disease, relapsed patients have few therapeutic options because after first line therapy, currently no standard of care exists. On the basis of endocrine positivity of most endometrioid ECs, Endocrine Therapy (ET) is a reasonable and widely accepted option. Better knowledge of molecular mechanisms involved in cancer highlighted the deregulated activity of Cyclin-Dependent Kinases (CDKs) in the cell cycle as a hallmark of carcinogenesis supporting the development of a new class of drugs: CDK inhibitors (CDKis). The aim of this review is to give an overview on CDKis preclinical, early clinical activity and future development in EC. Use of CDKis has a strong preclinical rationale but we have poor clinical data. Similar to breast cancer, most ongoing trials are investigating synergistic associations between CDKis and ET. These trials will probably help in defining the best clinical setting of CDKis in ECs, which are the best partner drugs, and how to manage CDKis toxicities with a focus on potential biomarkers of response.

Endometrial Carcinoma: Specific Targeted Pathways

Endometrial cancer (EC) is the most common gynecologic malignancy in the western world with more than 280,000 cases per year worldwide. Prognosis for EC at early stages, when primary surgical resection is the most common initial treatment, is excellent. Five-year survival rate is around 70 %.Several molecular alterations have been described in the different types of EC. They occur in genes involved in important signaling pathways. In this chapter, we will review the most relevant altered pathways in EC, including PI3K/AKT/mTOR, RAS-RAF-MEK-ERK, Tyrosine kinase, WNT/β-Catenin, cell cycle, and TGF-β signaling pathways. At the end of the chapter, the most significant clinical trials will be briefly discussed.This information is important to identify specific targets for therapy.

Cyclin D1 is significantly associated with stage of tumor and predicts poor survival in endometrial carcinoma patients

Cyclin D1 overexpression has been described to have oncogenic role and association with diagnosis, prognosis and survival in various tumors. This study will describe the immunohistochemical phenotype of cyclin D1, and investigate the correlation between these patterns of expression and clinicopathological parameters of endometrial carcinomas, to conclude the clinical relevance of cyclin D1 expression in the evolution of endometrial neoplasms. This study employed 101 endometrial tissue samples which include 71 endometrial carcinomas and thirty normal and benign endometrium cases. All these tissue samples were used in the assembly of tissue microarrays which have been utilized afterward in immunohistochemistry staining to detect cyclin D1 expression. Forty (56.3%) cases of endometrial carcinomas showed brown nuclear expression of cyclin D1 including 36 (61%) cases of endometrioid carcinomas, and 3 (33.3%) cases of serous carcinomas. Twenty three (76.6%) cases of control group demonstrated nuclear expression. High score cyclin D1 immunohistochemical staining has been significantly linked with patient age (P=0.0001). Large proportion of high score cyclin D1 immunohistochemical staining was observed in females who are <40years of age while high proportions of negative staining were observed in older age groups. Histologic type of tissue was also significantly related to cyclin D1 immunohistochemical staining (P-value=0.0001), high staining is more common in normal proliferative and secretory endometrium while serous carcinoma is more prevalent with negative staining. Stage of tumor was significantly associated with cyclin D1 immunohistochemical staining (P-value=0.029), proportion of stage III and IV are higher in negative cyclin D1 immunostaining. Significantly higher proportion of high score cyclin D1 immunostaining is observed in controls while higher proportion of negative cyclin D1 immunostaining is observed among carcinoma cases (P-value=0.0001). No significant associations between cyclin D1 immunohistochemical staining and grade, recurrence and alive status were observed. Significant different survival distributions were observed (P-value=0.011) and poor survival behavior was correlated with negative cyclin D1 immunohistochemical staining. In conclusion, greater frequency of cyclin D1 expression was revealed in normal endometrial tissues in comparison with carcinomas. The distribution pattern of cyclin D1 immunoexpression suggests poor prognoses in endometrial carcinoma patients.

Analysis of differentially expressed genes between endometrial carcinosarcomas and endometrioid endometrial carcinoma by bioinformatics

PURPOSE

This study aimed to explore the underlying molecular mechanisms of endometrial carcinosarcomas (ECS) and endometrioid endometrial carcinoma (EEC) by bioinformatics analysis.

METHODS

Gene expression profile GSE33723 was downloaded from the Gene Expression Omnibus. A total of 15 ECS and 23 EEC samples were used to identify the differentially expressed genes (DEGs) by significance analysis of microarrays. After construction of protein-protein interaction (PPI) network, Gene Ontology (GO) functional and pathway enrichment analyses of DEGs were performed, followed by network module analysis.

RESULTS

A total of 49 DEGs were identified between EEC and ECS samples. In the PPI network, TP53 (tumor protein p53) was selected as the highest degree, hub centrality and betweenness. The top 10 enriched GO terms including regulation of cell death and top 10 significant pathways including cell cycle were selected. After network module analysis, PIK3R1 (phosphoinositide-3-kinase, regulatory subunit 1) and AKT2 (v-akt murine thymoma viral oncogene homolog 2) were selected as the co-expressed genes in the states of ECS while STAT3 (signal transducer and activator of transcription 3) and JAZF (JAZF zinc finger 1) were selected as the co-expressed genes in the states of EEC.

CONCLUSIONS

The DEGs, such as TP53, PIK3R1 and AKT2 may be used for targeted diagnosis and treatment of ECS while STAT3 and JAZF1 may be served as a target for EEC.

Prognostic impact of transcription factor Fra-1 in ER-positive breast cancer: contribution to a metastatic phenotype through modulation of tumor cell adhesive properties

PURPOSE

The transcription factor Fos-related antigen-1 (Fra-1) has been described to affect the morphology, motility and invasive potential of breast cancer cells. Since tumor cell adhesion plays an essential role in the metastatic process, especially for extravasation from blood vessels, we investigated the influence of Fra-1 on breast cancer cell interactions with the endothelium.

METHODS

Using Fra-1-overexpressing MCF7 [weakly invasive, estrogen receptor (ER)-positive] and MDA MB231 (strongly invasive, ER-negative) cells, we performed dynamic cell flow adhesion assays on surfaces coated with E-selectin or with human pulmonary microvascular endothelial cells.

RESULTS

We found a significant increased adhesion of Fra-1-overexpressing MCF7 cells to E-selectin but also to activate endothelial cells, whereas the MDA MB231 cell line showed moderate enhanced cell rolling and tethering on both coated surfaces. These different adhesion behaviors corresponded to an up-regulation of various adhesion-related proteins such as CD44 and integrin α5 in Fra-1-overexpressing MCF7 cells measured by microarray analysis and flow cytometry in comparison with no deregulation of key adhesion molecules observed in Fra-1-overexpressing MDA MB231 cells. In line with these results and based on cDNA microarray data of breast cancer patients (n = 197), high Fra-1 expression significantly correlates with shorter overall survival and higher rate of lung metastasis in ER-positive breast cancer patients (n = 130), but has no impact on the prognosis of patients with ER-negative tumors.

CONCLUSION

Thus, in addition to its pro-invasive and pro-migratory effect, Fra-1 might influence the metastatic potential of breast cancer cells by changing the expression of adhesion molecules, resulting in increased adherence to endothelial cells under flow conditions.

Cell-cycle protein expression in a population-based study of ovarian and endometrial cancers

Aberrant expression of cyclin-dependent kinase (CDK) inhibitors is implicated in the carcinogenesis of many cancers, including ovarian and endometrial cancers. We examined associations between CDK inhibitor expression, cancer risk factors, tumor characteristics, and survival outcomes among ovarian and endometrial cancer patients enrolled in a population-based case-control study. Expression (negative vs. positive) of three CDK inhibitors (p16, p21, and p27) and ki67 was examined with immunohistochemical staining of tissue microarrays. Logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for associations between biomarkers, risk factors, and tumor characteristics. Survival outcomes were only available for ovarian cancer patients and examined using Kaplan-Meier plots and Cox proportional hazards regression. Among ovarian cancer patients (n = 175), positive p21 expression was associated with endometrioid tumors (OR = 12.22, 95% CI = 1.45-102.78) and higher overall survival (log-rank p = 0.002). In Cox models adjusted for stage, grade, and histology, the association between p21 expression and overall survival was borderline significant (hazard ratio = 0.65, 95% CI = 0.42-1.05). Among endometrial cancer patients (n = 289), positive p21 expression was inversely associated with age (OR ≥ 65 years of age = 0.25, 95% CI = 0.07-0.84) and current smoking status (OR: 0.33, 95% CI 0.15, 0.72) compared to negative expression. Our study showed heterogeneity in expression of cell-cycle proteins associated with risk factors and tumor characteristics of gynecologic cancers. Future studies to assess these markers of etiological classification and behavior may be warranted.

Prognostic value of cyclin B in endometrial endometrioid adenocarcinoma

Cyclins are a group of cell cycle regulatory proteins. Cyclin B acts as an activator to cyclin-dependent kinase 1 (CDK1), a protein kinase essential for G2/M phase transition. Deregulation of cyclins has been linked to a number of malignant neoplasms, but the impact on clinicopathological parameters seems to be cancer-specific. Overexpression of cyclin B has been shown to affect survival in some malignant tumors, including breast and esophageal cancer, but its impact on endometrial cancer has not been extensively studied. For this study, 211 endometrial endometrioid adenocarcinoma samples were obtained from patients surgically treated at the Oulu University Hospital. The samples were immunohistochemically stained and analyzed for cyclin B expression. The relationships between cyclin B expression and conventional prognostic factors were analyzed. A discrimination threshold for survival analyses was calculated by utilizing the receiver operator characteristic (ROC) method. Cyclin B expression correlated with grade and advanced stage. Survival analyses showed that cyclin B expression affects cancer-specific survival in univariate analysis. In multivariate analysis, the results were indicative that cyclin B may hold independent prognostic significance, but further studies are required to assess this.

Prognostic role of cell cycle and proliferative biomarkers in patients with clear cell renal cell carcinoma

PURPOSE

Cell cycle regulatory molecules are implicated in various stages of carcinogenesis. In this proof of principle study we systematically evaluate the association of aberrant expression of cell cycle regulators and proliferative markers and their effect on oncologic outcomes of patients with clear cell renal carcinoma.

MATERIALS AND METHODS

Immunohistochemistry for Cyclin D, Cyclin E, p16, p21, p27, p53, p57 and Ki67 was performed on tissue microarray constructs of 452 patients treated with extirpative therapy for clear cell renal cell carcinoma between 1997 and 2010. Clinical and pathological data elements were collected. A prognostic marker score was defined as unfavorable if more than 4 biomarkers were altered. The relationship between marker score and pathological features and oncologic outcomes was evaluated.

RESULTS

Median age was 57 years (range 17 to 85) and median followup was 24 months (range 6 to 150). An unfavorable marker score was found in 55 (12.2%) patients and was associated with adverse pathological features. A significant correlation between unfavorable marker score and disease-free survival (HR 26.62, 95% CI 43.38-100.04, p=0.000) and with cancer specific survival (HR 8.15, 95% CI 74.42-101.56, p=0.004) was demonstrated on Kaplan-Meier survival analysis. On multivariate analysis an unfavorable marker score was an independent predictor of disease-free survival (HR 2.63, 95% CI 1.08-6.38, p=0.033).

CONCLUSIONS

The cumulative number of aberrantly expressed cell cycle and proliferative biomarkers correlates with aggressive pathological features and inferior oncologic outcomes in patients with clear cell renal cell carcinoma. Our findings indicate that interrogation of cell cycle and proliferative markers is feasible, and further prospective pathway based exploration of biomarkers is needed.

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.

Briefly bound to activate: transient binding of a second catalytic magnesium activates the structure and dynamics of CDK2 kinase for catalysis

We have determined high-resolution crystal structures of a CDK2/Cyclin A transition state complex bound to ADP, substrate peptide, and MgF(3)(-). Compared to previous structures of active CDK2, the catalytic subunit of the kinase adopts a more closed conformation around the active site and now allows observation of a second Mg(2+) ion in the active site. Coupled with a strong [Mg(2+)] effect on in vitro kinase activity, the structures suggest that the transient binding of the second Mg(2+) ion is necessary to achieve maximum rate enhancement of the chemical reaction, and Mg(2+) concentration could represent an important regulator of CDK2 activity in vivo. Molecular dynamics simulations illustrate how the simultaneous binding of substrate peptide, ATP, and two Mg(2+) ions is able to induce a more rigid and closed organization of the active site that functions to orient the phosphates, stabilize the buildup of negative charge, and shield the subsequently activated γ-phosphate from solvent.

Involvement of cyclin B1 in progesterone-mediated cell growth inhibition, G2/M cell cycle arrest, and apoptosis in human endometrial cell

BACKGROUND

Progesterone plays an important role in the proliferation and differentiation of human endometrial cells (hECs). Large-dose treatment with progesterone has been used for treatment of endometrial proliferative disorders. However, the mechanisms behind remain unknown.

METHODS

To investigate the role of cyclin B1 in proliferation and differentiation of hECs in menstrual cycle, the expression of cyclin B1 throughout the menstrual cycle was evaluated in hECs. To determine the effects of progesterone on the proliferation, cell cycle progression and apoptosis of hECs and to test if cyclin B1 is involved in these effects, progesterone and/or Alsterpaullone (Alp, a specific inhibitor of Cyclin B1/Cdc2) were added to primary hECs. Cellular proliferation was evaluated with MTT test, cell cycle with propidium iodide (PI) staining and flow cytometry, apoptosis with FITC-Annexin V and the expression of cyclin B1 with Western blotting.

RESULTS

The expression level of cyclin B1 in secretory endometria was significantly lower than in proliferative endometria (p < 0.01). Progesterone significantly inhibited the growth of hECs in a concentration-dependent manner (P < 0.01). The treatment with progesterone significantly decreased the expression of cyclin B1, increased the proportions of cell in G2/M phase, and apoptotic cells (P < 0.05 for all). The presence of Alp significantly enhanced the effects of progesterone on cyclin B1 down-regulation, G2/M cell cycle arrest and induction of apoptosis (P < 0.01 for all).

CONCLUSION

Our findings suggest that cyclin B1 is a critical factor in proliferation and differentiation of hECs. Progesterone may inhibit cell proliferation, mediate G2/M cell cycle arrest and induce apoptosis in hECs via down-regulating Cyclin B1.

Involvement of Akt, Ras and cell cycle regulators in the potential development of endometrial hyperplasia in women with polycystic ovarian syndrome

OBJECTIVE

To examine whether the abundance, localization, and/or activity of cell cycle regulators CDK2, Cyclin E, p27, and survival proteins AKT and Ras in PCOS-associated endometria (with and without hyperplasia) differ from non-PCOS endometria.

METHODS

The expression of CDK2, Cyclin E, p27, AKT and Ras was measured by immunohistochemistry and/or Western blot in 9 normal endometria (NE), 12 endometria from PCOS patients without endometrial hyperplasia (PCOSE), 7 endometria from PCOS women with endometrial hyperplasia (HPCOSE), and 9 endometria from patients with endometrial hyperplasia (HE). The activity of CDK2 was assessed by an in vitro kinase assay.

RESULTS

CDK2, Cyclin E and p27 proteins were expressed mainly in the endometrial epithelial cells of the studied groups. No change in the activity of CDK2 was observed in total extracts obtained from the tissue samples. However, the nuclear expression of CDK2 in epithelial cells was slightly elevated in PCOSE and significantly increased in HPCOSE when compared to NE. Higher expression of p27 was detected in the cytoplasm of epithelial cells of PCOSE and HPCOSE when compared to NE. Also, we found an increment in Ser473-AKT phosphorylation and an over-expression of the Ras oncogene in endometria of patients with PCOS.

CONCLUSION

The PCOS condition is associated with increased Ser473-AKT phosphorylation, elevated expression of Ras, increased cytoplasmic abundance of p27, and increased nuclear abundance of CDK2 in the endometrial epithelial cells. These biological events could potentially provide a chance for endometrial cells from PCOS patients to exit the controlled cell cycle and become hyperplastic at a later stage.

A natural histone deacetylase inhibitor, Psammaplin A, induces cell cycle arrest and apoptosis in human endometrial cancer cells

OBJECTIVE

Histone deacetylase (HDAC) inhibitors are promising new class of anticancer agents that act by inhibiting cell proliferation and inducing cell cycle arrest of various cancer cells. Psammaplin A (PsA) is a phenolic natural product that has been isolated from marine sponges, and has been suggested to be a promising novel HDAC inhibitor. However, the precise mechanism of PsA as a HDAC inhibitor is poorly understood. This study investigated the anti-tumor effect of PsA on endometrial human cancer cells.

METHODS

The cell proliferation, cell cycle, and apoptosis were measured in Ishikawa endometrial cancer cells after PsA treatment.

RESULTS

PsA significantly inhibited the proliferation of Ishikawa cells in a dose-dependent manner. PsA markedly induced the expression of acetylated H3 and H4 histone proteins. In addition, PsA markedly up-regulated the expression of cyclin-dependent kinase inhibitor, p21(WAF1), and down-regulated the expression of pRb, cyclins, and CDKs, which lead to induce cell cycle arrest. Cell cycle analysis indicated that PsA treatment increased the proportion of cells in the G0/G1 and G2/M phases, and decreased the ratio of cells in the S phase.

CONCLUSION

The PsA treatment resulted in the significant induction of apoptosis, which was associated with p53 independent p21(WAF1) expression. These results suggest that PsA exhibits the antiproliferative effects on endometrial cancer cells through selective induction of genes related to cell cycle arrest and apoptosis.

P16INK4a overexpression independent of Human Papilloma Virus (HPV) infection in rare subtypes of endometrial carcinomas

In the current study, we evaluated p16 expression in rare subtypes of endometrial carcinomas, whose HPV status has been previously examined in order to establish the role of this protein in their pathogenesis. These rare subtypes of endometrial carcinomas are primary squamous endometrial carcinoma (ESCC), endometrial mucinous microglandular adenocarcinoma (EMMA), and endometrial transitional cell carcinoma (ETCC). All tissues, obtained at the time of hysterectomy, were fixed in 10% phosphate-buffered formalin and embedded in paraffin. Serial sections were made for hematoxylin and eosin staining and for immunohistochemistry. Although a previous PCR study has demonstrated that none of these neoplasms showed any signal for HPV DNA, these malignancies did display immunoreactivity for P16(INK4a). In ESCC, P16(INK4a) immunoreactivity was diffuse in 100% of neoplastic cells. In two cases of EMMA, positivity for P16INK4a was zonal. In ETCC, scattered cells were positive for P16INK4a protein. These findings suggest that alteration of p16 could play an etiologic role, without any association to HPV infections, in these rare endometrial carcinomas. However, in our view, other cases of these rare malignancies should be investigated in order to confirm this hypothesis.

Immunohistochemical features of a papillary squamous cell carcinoma of the endometrium with transitional cell differentiation

An 84-year-old woman underwent hysterectomy due to a friable endometrial mass infiltrating almost half way through the myometrial wall. The tumor consisted of papillary structures with thin fibrovascular cores covered by several layers of pleomorphic cells. The deeply located neoplastic cells were ovoid with a pale eosinophilic cytoplasm resembling urothelial cells. A diagnosis of papillary squamous cell carcinoma of the endometrium with transitional cell differentiation was made. Although she recovered well after surgery, she died one year later because of disseminated disease. In an attempt to obtain new insights into the physiopathology of this very rare tumor, an immunohistochemical panel with 32 markers was performed. The neoplastic cells were positive for cytokeratin 5, vimentin, p63, p21, VEGF, Ki67, BAG1, and bcl-2. The expression of BAG-1 and bcl-2 may suggest that anti-apoptotic stimuli are preponderant in this neoplasm.

Role of Fra-2 in breast cancer: influence on tumor cell invasion and motility

Fra-2 (Fos-related antigen 2) is a member of the Fos family of AP-1 transcription factors which is often up-regulated in mammary carcinomas. Previous results suggested that it might be involved in the regulation of breast cancer invasion and metastasis. In order to analyze the role of Fra-2 in breast cancer cells, it was silenced in the highly invasive MDA-MB231 cells using RNA interference. On the other hand, stable transfectants of the weakly invasive MCF7 cell line were established in order to analyze the effects of Fra-2 overexpression. In both approaches, cell proliferation was not or only weakly influenced by Fra-2. In contrast, the invasive potential of the cells was increased, and a weaker effect on motility was observed. By cDNA microarray analysis of the MCF7 transfectants followed by validation on a protein level, we identified several Fra-2 target genes which might be involved in cell invasion and migration, i.e., ALCAM and connexin 43. Additionally, mRNA expression levels of various genes which are associated with a more malignant behavior of the tumors in vivo were up- or downregulated, i.e., members of the MAGE family, S100P, TIMP2, IL24 etc. These results show that Fra-2 overexpression is associated with a more aggressive tumor phenotype and is probably involved in breast cancer progression in vivo.

Identification of molecular markers and signaling pathway in endometrial cancer in Hong Kong Chinese women by genome-wide gene expression profiling

Endometrial cancer is the third most common gynecologic malignancy and the ninth most common malignancy for females overall in Hong Kong. Approximately 80% or more of these cancers are endometrioid endometrial adenocarcinomas. The aim of this study was to reveal genes contributing to the development of endometrioid endometrial cancer, which may impact diagnosis, prognosis and treatment of the disease. Whole-genome gene expression analysis was completed for a set of 55 microdissected sporadic endometrioid endometrial adenocarcinomas and 29 microdissected normal endometrium specimens using the Affymetrix Human U133 Plus 2.0 oligonucleotide microarray. Selected genes of interest were validated by quantitative real-time-polymerase chain reaction (qRT-PCR). Pathway analysis was performed to reveal gene interactions involved in endometrial tumorigenesis. Unsupervised hierarchical clustering displayed a distinct separation between the endometrioid adenocarcinomas and normal endometrium samples. Supervised analysis identified 117 highly differentially regulated genes (>or=4.0-fold change), which distinguished the endometrial cancer specimens from normal endometrium. Twelve novel genes including DKK4, ZIC1, KIF1A, SAA2, LOC16378, ALPP2, CCL20, CXCL5, BST2, OLFM1, KLRC1 and MBC45780 were deregulated in the endometrial cancer, and further validated in an independent set of 56 cancer and 29 normal samples using qRT-PCR. In addition, 10 genes were differentially regulated in late-stage cancer, as compared to early-stage disease, and may be involved in tumor progression. Pathway analysis of the expression data from this tumor revealed an interconnected network consisting of 21 aberrantly regulated genes involved in angiogenesis, cell proliferation and chromosomal instability. The results of this study highlight the molecular features of endometrioid endometrial cancer and provide insight into the events underlying the development and progression of endometrioid endometrial cancer.

Growth regulation and transcriptional activities of estrogen and progesterone in human endometrial cancer cells

Estrogen-stimulated growth of the malignant human endometrium can be balanced by the differentiating properties of progesterone. To study the molecular basis behind this, gene expression profiling was performed using complementary DNA microarray analysis. In this study, the human endometrial cancer cell lines ECC-1 and PRAB-36 were used as models. The ECC-1 cell line, which expresses high levels of estrogen receptor alpha and is stimulated in growth by estrogens, was used to study estrogen regulation of gene expression. The Ishikawa sub-cell line PRAB-36, expressing both PRA and PRB, progesterone receptor isoforms, and inhibited in growth by progestagens, was used to study progesterone regulation of gene expression. Using these two well-differentiated human endometrial cancer cell lines, 148 estrogen- and 148 progesterone-regulated genes were identified. After functional classification, the estrogen- and progesterone-regulated genes could be categorized in different biologically relevant groups. Within the group of "cell growth and/or maintenance," 81 genes were clustered, from which a number of genes could be involved in arranging the cross talk that exists between estrogen and progesterone signaling. On the basis of analysis of the current findings, it is hypothesized that cross talk between estrogen and progestagen signaling does not occur by counterregulation of single genes, but rather at the level of differential regulation of different genes within the same functional families.

Expression of cyclin H in normal and cancerous endometrium, its correlation with other cyclins, and association with clinicopathologic parameters

Cyclins are known as regulatory proteins in cell cycle. Cyclin H is a part of cyclin H/Cdk7/Mat1 complex, which is necessary for cellular proliferation. This study was designed to investigate the correlation of cyclin H expression with tumorigenesis of the endometrium and clinicopathologic variables. Immunohistochemical staining using labeled streptavidin-biotin complex was performed on formalin-fixed, paraffin-embedded endometrial tissues of the proliferative, hyperplastic, and carcinomatous types. Immunostaining for cyclins A, B1, D1, D3, E, H, and cyclin dependent kinase 2 were evaluated. The expression of cyclins A, D1, D3, and H in hyperplasia was significantly more frequent than those of proliferative phase and less than those of endometrioid adenocarcinoma. The expression of cyclin H was correlated with lymphvascular space invasion and clinical stage in carcinoma but not with myometrial invasion, lymph node metastasis, and menopause status. The expression of cyclin H could be involved in the transformation of the endometrium into malignancy and might be a marker for more proliferative and malignant features. It might be one of the biomarkers for determining proliferative activity in endometrial hyperplasia and endometrioid adenocarcinoma.

p16, retinoblastoma (pRb), and cyclin D1 protein expression in human endometriotic and adenomyotic lesions

OBJECTIVE

To investigate the expression of p16, retinoblastoma (pRb), and cyclin D1 oncoproteins in endometriomas and adenomyosis.

DESIGN

Immunohistochemical study for p16, pRb, and cyclin D1 proteins in formalin-fixed paraffin-embedded endometriotic and adenomyotic tissues.

SETTING

University hospital.

PATIENT(S)

Tissues from 25 women with endometriomas and 31 women with adenomyosis were evaluated.

INTERVENTION(S)

Tissue samples were collected during gynecologic surgery and confirmed by histology to have endometriosis or adenomyosis. Nuclear expression of p16, pRb, and cyclin D1 proteins was examined by immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Distribution and intensity of immunostaining.

RESULT(S)

In the proliferative phase of the cycle, p16 was detected in 77% of adenomyosis tissues but in only 15% of endometriosis tissues. Moreover, in adenomyosis samples positive for p16, 100% of the adenomyotic cells expressed p16, whereas only 10%-20% of endometriosis cells from positive cases expressed p16. In contrast, pRb was detected in 28% of endometriosis cases but not in any adenomyotic tissues. Cyclin D1 was absent in both endometriotic and adenomyotic tissue samples.

CONCLUSION(S)

Differences in oncoprotein expression between endometriotic and adenomyotic tissues provide further evidence that the pathogenesis of endometriosis is different from that of adenomyosis.

Cell cycle regulators and apoptosis-associated proteins in relation to proliferative activity and degree of apoptosis in HNPCC versus sporadic endometrial carcinoma

AIMS

Mismatch repair gene malfunction occurs early in the carcinogenesis of hereditary non-polyposis colorectal cancers (HNPCCs), leading to an accelerated accumulation of mutations and possibly to change in expression of cell cycle proteins. There is strong evidence that tumorigenesis in HNPCCs differs from sporadic ones. HNPCC-related endometrial cancers are less well studied. Our aim was to compare expression of cell cycle and apoptosis-related proteins in relation to proliferation and apoptosis in HNPCC-related and sporadic endometrial cancers to identify differences in their carcinogenetic pathways.

METHODS AND RESULTS

Eighteen HNPCC-related endometrial cancers, each matched by tumour type, stage and grade with two sporadic endometrial cancers, were examined for proliferation, apoptosis and the expression of oestrogen and progesterone receptors, cyclin B1, D3 and E, p21, p27, bcl-2, bax, p53 and COX-2. No differences in proliferation or apoptotic indices were detected between HNPCC-related and sporadic endometrial cancers. Cyclin B1 expression was significantly higher in HNPCC-related cancers than in sporadic endometrial cancers. More HNPCC-related endometrial cancers had total loss of bax expression.

CONCLUSIONS

Apart from differences in cyclin B1 and bax expression, HNPCC-related and sporadic endometrial cancers are comparable. The subtle differences detected are consistent with the minor clinical diversity between HNPCC-related and sporadic endometrial cancers.

T cell-dependent antibody responses against aberrantly expressed cyclin B1 protein in patients with cancer and premalignant disease

PURPOSE

Cyclin B1-derived peptides were shown by us to be targets of tumor-specific CD8(+) T cells in patients with breast and head and neck cancer. We obtained further evidence of cyclin B1 immunogenicity and its potential to serve as a tumor-specific antigen by analyzing its ability to elicit T cell-dependent humoral immune responses in vivo in patients with different types of tumors.

EXPERIMENTAL DESIGN

Recombinant cyclin B1 protein from two different sources was purified and used as antigen in ELISA assays to test sera from patients with breast, pancreatic, colon, and lung cancer for the presence of anti-cyclin B1 antibody. We also analyzed patients with benign lung disease, premalignant disease, and a known history of heavy smoking.

RESULTS AND CONCLUSIONS

Cyclin B1 elicits helper T cell-dependent antibody responses in vivo. Tumors with higher level of cyclin B1 expression elicit higher anti-cyclin B1 antibody levels. Antibodies in patients with breast and colon cancer are primarily of the IgG isotype whereas patients with pancreatic and lung cancer have in addition anti-cyclin B1 IgA. Cyclin B1-specific IgG was also detected in long-term smokers and in patients with preneoplastic lung disease. Immune responses to aberrantly expressed cyclin B1 in tumors and premalignant lesions should be further explored as diagnostic and prognostic markers, in addition to their immunotherapeutic potential.

Clinicoprognostic significance of pRb1 pathway alterations in uterine endometrial adenocarcinoma

Components of the pRb1 pathway play a pivotal role in regulating the G1/S transition in the cell cycle. This study investigated the association between pRb1-cyclin D1-cdk4-p16INK4A pathway alterations and the clinical and prognostic utility for women affected by primary uterine endometrial adenocarcinoma (EC). The study population consisted of 50 cases of EC patients who were investigated for RB1 and CDKN2A (alias p16INK4A) gene alterations, as well as for the expression pattern of pathway proteins. Altogether, pRb1 pathway alterations were noted in 54% (27 of 50) of ECs, and more frequently in advanced-stage uterine carcinomas (P=0.024, Fisher exact test). Loss of heterozygosity abnormalities in RB1 and CKDN2A coexisted with altered cyclin D1-cdk4 complex immunoreactivity only in 2 patients, both less than 50 years of age. With respect to pRb1 pathway alterations, however, the recurrence rate was not significantly different (P=0.477; log-rank test). Our results suggest that the progression of uterine endometrial adenocarcinoma is generally accompanied by increased frequency of pRb1 pathway alterations. Alterations of the retinoblastoma pathway may not be necessarily associated with the recurrence of EC.

Alterations of pRb1-cyclin D1-cdk4/6-p16(INK4A) pathway in endometrial carcinogenesis

The retinoblastoma protein pathway (pRb1-cyclin D1-cdk4/6-p16(INK4A)) participates in the regulation of the cellular processes at the transition of G1/S phases of the cell-cycle. Derailments of this pathway, caused either by lack of pRb1 or p16(INK4A) expression or overexpression of cyclin D1 and/or cdk4/6, are implicated in the deregulation of the cell-cycle machinery, resulting in uncontrolled cell proliferation, tumor heterogeneity, invasion and metastasis. Several studies conducted so far have assessed the deregulation of the pRb1-pathway components in various human tumors and cell-lines, provided these pathway alterations play an obligatory role in tumorigenesis. This review briefly summarizes the current information on the pRb1-cyclin D1-cdk4/6-p16(INK4A) alterations in sporadic uterine cancer, placing emphasis on the influence on the dualistic model of endometrial carcinogenesis.

Distinction of Endocervical and Endometrial Adenocarcinomas

Determining the origin of uterine adenocarcinomas can be difficult in biopsy and curettage specimens because the morphologic spectrum of endocervical and endometrial adenocarcinomas overlaps. In hysterectomy specimens, the primary site is often equivocal for tumors that involve the lower uterine segment and endocervix and lack identifiable precursor lesions. Most endocervical adenocarcinomas (ECAs) contain high-risk human papillomavirus (HPV) DNA, whereas endometrial adenocarcinomas (EMAs) rarely do. p16 is an inhibitor ofcyclin-dependent kinases, and overexpression of p16 has been observed in cervical intraepithelial lesions and invasive carcinomas associated with high-risk HPV types. We evaluated the utility of immunohistochemistry for p16 in the distinction of ECAs and EMAs. p16 expression was assessed in 24 unequivocal EMAs and 19 unequivocal ECAs and correlated with HPV DNA detection by in situ hybridization and polymerase chain reaction. These assays were then used to assist in the classification of four lower uterine segment/upper endocervical adenocarcinomas (LUS/EC-A) of equivocal origin. p16 expression was moderate-strong and diffuse in 18 ECAs (median 90% of tumor cells positive, range 90%-100%), and weak and diffuse in one. Fourteen of these were positive for HPV DNA, whereas 5 lacked detectable HPV DNA by in situ hybridization; one of these 5 was positive by polymerase chain reaction. In contrast, EMAs displayed weaker staining with patchy distribution (median 30% of tumor cells positive, range 5%-70%) and none contained HPV DNA by in situ hybridization. Two LUS/EC-As, which were positive for HPV, exhibited strong, diffuse p16 expression, consistent with endocervical origin of the tumors. The remaining 2 LUS/EC-As showed patchy p16 staining and did not contain detectable HPV DNA, consistent with the endometrial origin of the tumors. The p16 expression pattern can distinguish ECAs from EMAs. Compared with HPV DNA detection by in situ hybridization, p16 immunohistochemistry appears to be a more sensitive and easier to perform method for distinguishing ECAs from EMAs, can be used to assist in the classification of LUS/EC-As of equivocal origin, and should be evaluated for its utility in the prospective classification of uterine adenocarcinomas in curettage specimens prior to hysterectomy.

p16INK4A alterations are accompanied by aberrant protein immunostaining in endometrial carcinomas

PURPOSE

To date, the significance of p16INK4A tumor suppressor gene inactivation in sporadic endometrial cancer (EC) has only rarely been described. In this study, we examined the alteration type and frequency of gene alterations [point mutations, aberrant promoter methylation and loss of heterozygosity (LOH)] in 50 sporadic ECs, and correlated the genetic findings with the immunohistochemical expression of the p16INK4A protein and the classical clinicopathological features.

METHODS

Gene mutations were detected by PCR-SSCP-sequencing analysis, promoter hypermethylation by methylation-specific PCR (MSP), and LOH by PCR of the STS-marker c5.1.

RESULTS

In total, p16INK4A alterations were found in 14 of 50 (28%) sporadic ECs. In six (12%) cases, two alterations occurred simultaneously. Partial p16INK4A deletions were found in four of 50 (8%) samples. There was one missense mutation (codon 70; CCC-->GCC) and one frameshift mutation (1-bp deletion in exon 2). Only 2 of 47 (4.2%) tumors exhibited aberrant promoter methylation. An allelic loss was detected in 12 of 50 (24%) carcinomas with a higher incidence in advanced endometrial carcinomas than in early-stage uterine tumors. p16INK4A alterations were generally accompanied by gene silencing, confirmed by aberrant protein immunostaining ( r=-0.442; P=0.001). There was a significant difference in the frequency of p16INK4A alterations between early (stage I; 18%) and advanced (stages II-IV; 58%) ECs ( P=0.022). One case showed complete protein loss, but absence of genetic alterations.

CONCLUSIONS

Our data indicate that p16INK4A inactivation plays a role in the tumorigenesis of the subset of sporadic ECs, particularly in cases exhibiting an aggressive clinical behavior. We demonstrate that p16INK4A methylation can act efficiently and similarly to other genetic alterations as one of the two necessary hits according to the Knudson two-hit hypothesis of tumor suppressor gene inactivation.

Role of cell-cycle regulatory proteins in gynecological cancer

Human malignant tumors are characterized by abnormal proliferation resulting from alterations in cell-cycle regulatory mechanisms. This review summarizes the current knowledge about these aberrations in malignant tumors of the ovary, endometrium, cervix uteri, and vulva. The data indicate that analysis of single cell cycle stimulating or inhibiting proteins partly produces unexpected, apparently paradoxical results, and cell-cycle regulatory pathways should be regarded as a whole in order to identify the molecular mechanisms leading to abnormal tumor cell proliferation. For the papillomavirus (HPV)- associated cervical and vulvar carcinomas, the manifold effects of the viral oncogenes E6 and E7 on cell-cycle control are described.

Improved endometrial assessment using cyclin E and p27

OBJECTIVE

To evaluate endometrial expression of cyclin E and p27 in fertile and infertile women.

DESIGN

Retrospective clinical study.

SETTING

University medical center and private practice.

PATIENT(S)

Thirty-three fertile volunteers, 83 women seeking infertility treatment, and 23 women undergoing mock cycles.

INTERVENTION(S)

Endometrial biopsy.

MAIN OUTCOME MEASURE(S)

Cyclin E and p27 immunohistochemistry.

RESULT(S)

Glandular cyclin E and p27 expression dramatically changed in intensity and subcellular localization throughout the menstrual cycle. In normal control biopsies, glandular cyclin E progressed from the basal to the lateral cytoplasm (midproliferative phase) to the nucleus (days 18 to 19) and was absent in biopsies after day 20. First appearing on days 17 to 19, p27 was found only in the nuclei. Cyclin E was more frequently seen after day 20 in infertility patients. In the hyperstimulated cycles, staining for cycle E in proliferative samples was more intense than in the natural cycles, but p27 staining was unchanged.

CONCLUSION(S)

Cyclin E and p27 may be clinically useful markers of development in the endometrium. As cell cycle regulators, cyclins reveal underlying biochemical processes driving endometrial progression and may partly represent the means by which estrogen and progesterone regulate this dynamic tissue.

Selective interactions of Kruppel-like factor 9/basic transcription element-binding protein with progesterone receptor isoforms A and B determine transcriptional activity of progesterone-responsive genes in endometrial epithelial cells

The Sp/KLF transcription factor basic transcription element-binding protein (BTEB1) regulates gene transcription by binding to GC-rich sequence motifs present in the promoters of numerous tissue-specific as well as housekeeping genes. Similar to other members of this family, BTEB1 can act as a transactivator or transrepressor depending on cell and promoter context, although the molecular mechanism underlying these distinct activities remains unclear. Here we report that BTEB1 can mediate signaling pathways involving the nuclear receptor for the steroid hormone progesterone in endometrial epithelial cells by its selective interaction with the progesterone receptor (PR) isoforms, PR-A and PR-B. Functional interaction with ligand-activated PR-B resulted in superactivation of PR-B transactivity, facilitated the recruitment of the transcriptional integrator CREB-binding protein within the PR-dimer, and was dependent on the structure of the ligand bound by PR-B. By contrast, BTEB1 did not influence agonist-bound PR-A transactivity, although it augmented PR-A inhibition of PR-B-mediated transactivation as well as potentiated ligand-independent PR-A transcriptional activity in the presence of CREB-binding protein. We also demonstrate similar positive modulatory actions of BTEB1-related family members Krüppel-like family (KLF) 13/FKLF2/BTEB3 and Sp1 on PR-B transactivity. Further, we provide support for the potential significance of the selective functional interactions of PR isoforms with BTEB1 in the peri-implantation uterus using mouse and pig models and in the breast cancer cell lines MCF-7 and T47D. Our results suggest a novel mechanism for the divergent physiological consequences of PR-A and PR-B on progesterone-dependent gene transcription in the uterus involving select KLF members.

Immunohistochemical expression of cyclin E in endometrial adenocarcinoma (endometrioid type) and its clinicopathological significance

PURPOSE

Cyclin E is known as a G1-S phase regulatory protein and its abnormal expression has been implicated in cellular proliferation. This study aimed to investigate the correlation of cyclin E expression with tumorigenesis of the endometrium, proliferative activity, and clinicopathological features of endometrial adenocarcinoma.

METHODS

Immunohistochemical staining for cyclin E in addition to cyclin-dependent kinase 2 (cdk2), Ki67, p27, and p53 was performed by the labeled streptavidin-biotin method on formalin-fixed, paraffin-embedded tissues of normal endometria (20 cases), endometrial hyperplasias (20 cases), and endometrial adenocarcinomas (endometrioid type) (127 cases). Positive staining was expressed as a labeling index (LI) based on percentages of positive nuclei in tumor cells.

RESULTS

Immunohistochemistry showed that the nuclei of the cells were positive for cyclin E. Both proliferative and secretory endometria, and endometrial hyperplasia regardless of type were negligible for cyclin E expression. The expression in normal endometrium and hyperplasia was significantly less than that in endometrial adenocarcinomas (P<0.0001). LIs of cyclin E in well-differentiated, moderately differentiated, and poorly differentiated endometrial adenocarcinomas were 31.5+/-33.3%, 37.8+/-31.9%, and 51.1+/-30.8%, respectively. Cyclin E expression increased significantly more in histological grades. The LI of cyclin E in carcinoma was positively correlated with that of cdk2, Ki67, and p53 but not with p27. The cyclin E expression was correlated with myometrial invasion and lymph-vascular space involvement, but not with FIGO stage, lymph node metastasis, coexisting endometrial hyperplasia, estrogen receptor, progesterone receptor, and menopause.

CONCLUSION

Cyclin E as a complex with cdk2 is associated with carcinogenesis and disease progression in endometrial adenocarcinoma, and might be a prognostic indicator of endometrial adenocarcinoma.