PTEN mutations in endometrial carcinomas: a molecular and clinicopathologic analysis of 38 cases

Molecular features for timely cancer diagnosis and treatment - tumors of the ovary, fallopian tube and endometrium

Gynecologic pathology has moved, within only a few years, from being a diagnostic area devoid of molecular testing into a diagnostic discipline in which such analyses are becoming routine. The direct relevance of molecular characterization to the choice of treatment of patients with carcinomas originating in both the uterus and adnexae makes it likely that such testing will only expand along with our understanding of the molecular make-up of these tumors. As a consequence, gynecologic pathologists have become an integral part of patient management, rather than lab personnel providing external services.In parallel, molecular testing is expanding as a tool for diagnosing rare tumors affecting these organs, including soft tissue tumors, sex cord-stromal tumors and germ cell tumors, as well as other rare entities. Increased knowledge in this area bears directly on the ability to diagnose these tumors in a reproducible manner, as well as recognize and consult on genetic diseases. Hopefully, despite the inherent difficulty in studying rare cancers, it will also translate into new therapeutic options for the malignant ones among these rare cancers.

Assessment of endometrial carcinoma on biopsy as a predictor of final surgical pathology: Are we doing it right? A completed audit cycle and recommendations

Background

Typing and grading of endometrial carcinomas (ECs) on small biopsy specimens is crucial to determine the need for full surgical staging. Histological subtype and grade are key factors available for risk stratification before surgery. However, this can be diagnostically challenging on small biopsy specimens, especially when morphologic features are subtle or overlapping.

Aims

The aims of this audit were to assess concordance of endometrial carcinomas on biopsy specimens with hysterectomy specimens and to determine if the immunohistochemistry (IHC) panel being used in our practice was adequately subtyping ECs.

Settings and Design

The audit was approved by the Clinical Effectiveness Team of the Royal College of Pathologists (UK) as meeting all the criteria and standards set out by the College.

Materials and Methods

Biopsies from 67 cases of EC were compared for histological subtype and grade of endometrioid carcinoma with resection specimens. A re-audit was carried out on 59 cases after implementation of changes recommended by the initial audit.

Results

Two of 35 (6%) tumours defined as G1 on biopsy were upgraded (to G2) on final pathology, as was one of 7 (14%) G2 tumours (to G3). One of these cases had solid areas just amounting to more than 6% on resection. In the second case, a comment was made that assessment had been difficult as the specimen was suboptimally fixed, but nuclei appeared atypical. Of seven G2 biopsies, one case was upgraded to grade 3 on final pathology based on proportion of solid areas. Our data show lower rates of discordance as compared to previous studies and on re-audit, the concordance between endometrioid and nonendometrioid serous carcinoma improved with the addition of immunohistochemistry (IHC) for Phosphatase and tensin homolog (PTEN) to biopsies.

Conclusions

PTEN IHC can complement other stains and aid in the distinction of grade 3 endometrioid carcinoma from serous carcinoma on endometrial biopsies.

Finding the junction between claudins and endometrial carcinoma

Endometrial carcinoma (EC) defines a heterogeneous group of neoplastic diseases originating from the transformation of endometrial cells that constitute the internal lining of the uterus. To date several molecular targets have been analysed to describe the natural course of the disease, claudins being among these. Claudins are the main components of tight junctions (TJs), and their main functions are ascribed to the compartmentalization of tissues and cell-cell communication by means of intracellular ions diffusion: these features are typical of epithelial cells. Their overexpression, mis-localization or loss contribute to the malignancy of EC cells. This review collected all available data regarding the expression, regulation and claudin-related signaling pathways to provide a comprehensive view on the influence of claudin in EC progression. Further, the translational potential of claudin differential expression was explored, indicating that their role in personalized medicine could also contribute to EC therapy besides their employment for diagnosis and prognosis.

MicroRNA 182, 183, 200a, and 200b exhibit strong correlations but no involvement in PTEN protein regulation in uterine endometrial carcinoma

OBJECTIVE

In this study, we focused on five microRNAs (miRNAs) that have been reported to regulate phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene expression, namely miR-182, miR-183, miR-200a, miR-200b, and miR-205, and examined their relationships with PTEN protein expression in endometrial cancer tissues.

METHODS

By utilizing paraffin-embedded blocks of normal endometrium (NE) and endometrial carcinoma (EC) tissue (40 cases each), we measured the expression of miRNAs by real-time PCR. Conversely, we examined PTEN protein expression by immunohistochemistry and computer-assisted image analysis.

RESULTS

The expression of all five miRNAs was significantly higher in the EC group than in the NE group (all P ≤ 0.0001). There was no inverse correlation between PTEN positivity in glandular and/or stromal areas and the expression of the five miRNAs in both groups. Conversely, miR-182, miR-183, miR-200a, and miR-200b displayed similar expression patterns in the EC group, whereas miR-205 displayed moderate correlations with the other four miRNAs.

CONCLUSION

Using endometrial cancer tissues, we found for the first time that miR-182, miR-183, miR-200a, and miR-200b were strongly correlated with each other, whereas miR-205 was not strongly correlated with the other four miRNAs. In addition, the five miRNAs examined in this study only had weak effects on PTEN protein expression based on the lack of clear inverse correlations.

Bone Marrow-Derived Cells in Endometrial Cancer Pathogenesis: Insights from Breast Cancer

Endometrial cancer is the most common gynecological cancer, representing 3.5% of all new cancer cases in the United States. Abnormal stem cell-like cells, referred to as cancer stem cells (CSCs), reside in the endometrium and possess the capacity to self-renew and differentiate into cancer progenitors, leading to tumor progression. Herein we review the role of the endometrial microenvironment and sex hormone signaling in sustaining EC progenitors and potentially promoting dormancy, a cellular state characterized by cell cycle quiescence and resistance to conventional treatments. We offer perspective on mechanisms by which bone marrow-derived cells (BMDCs) within the endometrial microenvironment could promote endometrial CSC (eCSC) survival and/or dormancy. Our perspective relies on the well-established example of another sex hormone-driven cancer, breast cancer, in which the BM microenvironment plays a crucial role in acquisition of CSC phenotype and dormancy. Our previous studies demonstrate that BMDCs migrate to the endometrium and express sex hormone (estrogen and progesterone) receptors. Whether the BM is a source of eCSCs is unknown; alternatively, crosstalk between BMDCs and CSCs within the endometrial microenvironment could be an additional mechanism supporting eCSCs and tumorigenesis. Elucidating these mechanisms will provide avenues to develop novel therapeutic interventions for EC.

Histological and Somatic Mutational Profiles of Mismatch Repair Deficient Endometrial Tumours of Different Aetiologies

BACKGROUND

Mismatch repair deficient (MMRd) tumours may arise from somatic events acquired during carcinogenesis or in the context of Lynch syndrome (LS), an inherited cancer predisposition condition caused by germline MMR pathogenic variants. Our aim was to explore whether sporadic and hereditary MMRd endometrial cancers (EC) display distinctive tumour biology.

METHODS

Clinically annotated LS-EC were collected. Histological slide review was performed centrally by two specialist gynaecological pathologists. Mutational analysis was by a bespoke 75- gene next-generation sequencing panel. Comparisons were made with sporadic MMRd EC. Multiple correspondence analysis was used to explore similarities and differences between the cohorts.

RESULTS

After exclusions, 135 LS-EC underwent independent histological review, and 64 underwent mutational analysis. Comparisons were made with 59 sporadic MMRd EC. Most tumours were of endometrioid histological subtype (92% LS-EC and 100% sporadic MMRd EC, respectively, p = NS). Sporadic MMRd tumours had significantly fewer tumour infiltrating lymphocytes (p ≤ 0.0001) and showed more squamous/mucinous differentiation than LS-EC (p = 0.04/p = 0.05). PTEN mutations were found in 88% sporadic MMRd and 61% LS-EC, respectively (p < 0.001). Sporadic MMRd tumours had significantly more mutations in PDGFRA, ALK, IDH1, CARD11, CIC, MED12, CCND1, PTPN11, RB1 and KRAS, while LS-EC showed more mutations affecting SMAD4 and ARAF. LS-EC showed a propensity for TGF-β signalling disruption. Cluster analysis found that wild type PTEN associates predominantly with LS-EC, whilst co-occurring mutations in PTEN, PIK3CA and KRAS predict sporadic MMRd EC.

CONCLUSIONS

Whilst MMRd EC of hereditary and sporadic aetiology may be difficult to distinguish by histology alone, differences in infiltrating immune cell counts and mutational profile may predict heterogenous responses to novel targeted therapies and warrant further study.

Diagnosis and management of an endometrial cancer patient with Cowden syndrome

Somatic PTEN alterations are common in endometrial carcinoma (EC), but in rare cases PTEN mutations are associated with inherited syndromes. Here, we present a case of Cowden syndrome-associated EC. We discuss clinical, pathologic and molecular features of her tumor and PTEN-mutated EC, inherited syndromes predisposing to EC and PTEN-targeted therapies.

Does obesity modify the expression of cyclin D1 and pten in endometrial polyps in postmenopausal women?

To assess cyclin D1 and PTEN immunoexpression in benign endometrial polyps (EPs) in asymptomatic postmenopausal women and its correlation with obesity. Methods: This was a cross-sectional study based on data from a sample of 52 patients diagnosed with EP between February 2018 and January 2019. The women included in this study were amenorrheal for at least 1 year and were asymptomatic (no postmenopausal bleeding). Obesity defined by body mass index (BMI) was investigated for correlation with Cyclin-D1 and PTEN gene expression (immunohistochemistry) in glandular and stromal compartments of polyps. Results: No significant differences among groups were identified in any clinical and epidemiological parameter (age, age of menopause, time since menopause, number of gestations, polyp size, leucocyte count, fasting blood glucose and basic pathologies), except for BMI. Body mass index did not alter PTEN or Cyclin D1 immunoexpression. Conclusion: Our study shows that obesity does not appear to be a relevant factor in the immunoexpression of PTEN and Cyclin D1 in benign EP, in either the stromal or glandular compartments.

Expression of p53 and PTEN in human primary endometrial carcinomas: Clinicopathological and immunohistochemical analysis and study of their concomitant expression

Endometrial carcinoma is a common malignancy of the female genital tract. Alterations in the expression levels of various oncogenes and tumor suppressor genes serve important roles in the carcinogenesis and biological behavior of endometrial carcinoma. The aim of the present study was to evaluate the combination and individual expression of p53 and phosphatase and tensin homolog (PTEN) protein in human endometrial carcinoma. In addition, the correlation of these proteins with clinicopathological parameters was also assessed. Retrospective immunohistochemical analysis of the expression of p53 and PTEN tumor suppressor proteins was conducted in 99 women with endometrial carcinoma. The overall rate of p53 and PTEN positivity was 89 and 77%, respectively, according to the sum of stain intensity and scores of immunopositive cells. The sum of p53 positivity correlated strongly with PTEN expression (ρ=0.256; P=0.044). The concomitant sum of p53 and PTEN expression was identified in 45% of patients with endometrial adenocarcinoma. Notably, the sum of the immunohistochemical expression of p53 was significantly correlated with patient age (P=0.037), histologic type (P=0.008), histologic grade (P=0.002) and fallopian and/or ovarian invasion (P=0.014). Furthermore, PTEN expression was associated with myometrial invasion (ρ=−0.377; P=0.002) and clinical stage (P=0.019). In addition, concomitant p53 and PTEN expression was correlated with patient age (P=0.008) and histologic differentiation (P=0.028). The findings indicated a correlation between the expression of p53 and PTEN in endometrial adenocarcinoma, which suggested an intrinsic association between expression levels of these tumor suppressor genes. The study also suggested that concomitant p53 and PTEN expression contributed in characterizing the tumor behavior of endometrial carcinoma. Taken together, the present study suggested the combined expression of p53 and PTEN in the development of high-grade endometrial carcinoma in older patients. In addition, the findings indicated activation of different molecular pathways in the tumor progression between low-grade and high-grade endometrial carcinomas.

Estrogen affects the negative feedback loop of PTENP1-miR200c to inhibit PTEN expression in the development of endometrioid endometrial carcinoma

Endometrial carcinoma is one of the most common malignancies in the female reproductive system. It is well-known that estrogen plays an important role in the pathogenesis of endometrioid endometrial carcinoma (EEC), and induces the cancer suppressor gene PTEN deletion. However, how estrogen affects PTEN expression remains unknown. In the present study, we found in 40 EEC specimens, miR-200c level was higher in most cancer areas than that in the adjacent normal endometrium, while PTEN and PTENP1 were lower. Moreover, the expression of PTEN/PTENP1 and miR-200c also showed a converse relationship in EEC cell lines. In addition, we demonstrated that miR-200c bound directly to PTEN and PTENP1, and PTENP1 could reverse miR-200c inhibition function to PTEN using a dual-luciferase reporter and RNA binding protein immunoprecipitation (RIP) assays. Next, 17β-estradiol (E2) treatment could improve miR-200c and drop the PTEN level, which caused a consequential increase of the phospho-PI3K-AKT pathway genes. When we stably knocked down estrogen receptor α (ERα) expression in the EEC cell line, the effects of E2 on miR-200c and PTEN declined. In addition, it was demonstrated that E2 might modulate cell proliferation, migration and invasion relying on the expression of miR-200c. Taken together, it can be concluded that estrogen improves the miR-200c level by combining with ER, PTENP1 and PTEN could be inhibited by miR-200c, and then activate the PI3K-AKT pathway. This work provided a new mechanism of EEC development and a new potential therapeutic target.

Expression of phosphatase and tensin homologue in imprint smears of endometrial carcinoma

OBJECTIVE

The aims of this study were to determine the expression of phosphatase and tensin homologue (PTEN) in endometrial adenocarcinomas (as a potential prognostic indicator before treatment) in imprint smears and to correlate the results with clinicopathological parameters of primary untreated endometrial cancer patients.

METHODS

A total of 126 patients with endometrial carcinoma were evaluated with samples freshly resected after a total abdominal hysterectomy during a 29-month period. The expression of PTEN was assessed by immunocytochemistry.

RESULTS

In total, 102 cases were type I and 24 type II endometrial adenocarcinomas. High expression of PTEN was more frequent in type I (42/102) compared to type II (6/24) adenocarcinomas, to less advanced and aggressive clinical stage (stage I: 41/79, stage II: 5/13, stage III: 2/19, stage IV: 1/15) as well as in low grade (grade 1: 26/42, grade 2: 20/57) compared to high-grade (grade 3: 8/27) carcinomas. The nonaffected lymph nodes showed high expression of PTEN (in 43.3%) than the affected lymph nodes (in 5.9%). Also, in 45 out of 74 cases with myometrial invasion <50%, there was positive expression of PTEN in contrast to 12 out of 52 cases with depth of myometrial invasion >50%.

CONCLUSIONS

Immunocytochemical findings from PTEN stain, in addition to cytomorphological features, appeared to be a useful marker in the diagnosis and in the postoperative prognosis of endometrial carcinoma in endometrial cytology with imprint smears and that high PTEN expression is related to morphological features of less aggressiveness tumours.

Single nucleotide polymorphisms rs701848 and rs2735343 in PTEN increases cancer risks in an Asian population

We performed this meta-analysis to analyze the cancer risk to individuals carrying the rs701848 and rs2735343 single nucleotide polymorphisms (SNPs) in the phosphatase and tensin homolog (PTEN) gene. We searched the PubMed, EMBASE, Cochrane library and the national knowledge infrastructure of China (CNKI) databases and identified 18 eligible case-control studies with 5458 cases and 6003 controls for rs701848 as well as 5490 cases and 6209 controls for rs2735343. Our analyses demonstrated that cancer risk was associated with rs701848 in the recessive model (CC vs. CT+TT, OR=1.169, 95% CI: 1.061-1.288) and with rs2735343 in the dominant model (GC+CC vs. GG, OR=0.758, 95% CI: 0.590-0.972). Subgroup analysis showed that in Asian subjects, carrying the C allele of rs701848 or GG genotype of rs2735343 was associated with increased cancer risk. Moreover, Asian subjects carrying the TC/CC genotype or C allele of rs701848 were associated with increased risk of esophageal squamous cell cancer. This meta-analysis indicates that the PTEN rs701848 (CC) and rs2735343 (GG) polymorphisms are associated with increased cancer risk in Asian subjects.

Molecular Pathology: Predictive, Prognostic, and Diagnostic Markers in Uterine Tumors

This article focuses on the diagnostic, prognostic, and predictive molecular biomarkers in uterine malignancies, in the context of morphologic diagnoses. The histologic classification of endometrial carcinomas is reviewed first, followed by the description and molecular classification of endometrial epithelial malignancies in the context of histologic classification. Taken together, the molecular and histologic classifications help clinicians to approach troublesome areas encountered in clinical practice and evaluate the utility of molecular alterations in the diagnosis and subclassification of endometrial carcinomas. Putative prognostic markers are reviewed. The use of molecular alterations and surrogate immunohistochemistry as prognostic and predictive markers is also discussed.

Further insight into prognostic factors in endometrial cancer: the new serum biomarker HE4

INTRODUCTION

Endometrial cancer (EC) is one of the most common gynecological cancer worldwide. To date, no good markers are routinely used in clinical practice for prognosis and monitoring. Areas covered: During the last years, an increasing interest in literature has been growing on HE4 (Human epididimis 4). Therefore, we aimed to gather all the evidence reported in literature analysing the potential prognostic value of HE4, compared to the well know tumor's features (histological type and grade, stage of disease, depth of myometrial invasion, lymphovascular space involvement and cervical involvement). Expert commentary: The analysis of data suggests that HE4 seems to have a good performance in prognosis and monitoring of the disease, helping to schedule the appropriste timing of imaging and surgery in a more individualized fashion. However, these findings surely require a validation in a larger cohorts of patients. Probably, in the next five years, prospective randomized trials will be performed to confirm the prognostic role of HE4 in EC and to find a tailored EC management strategy.

Molecular Analysis of Single Tumor Glands Using the Crypt Isolation Method in Endometrial Carcinomas

OBJECTIVE

Endometrial adenocarcinomas are characterized by the presence of many single tumor glands in which multiple genetic changes have accumulated. To elucidate the differences in molecular abnormalities among single tumor glands, individual tumor glands were analyzed and microsatellite alterations (loss of heterozygosity (LOH) and microsatellite instability [MSI]) were examined using the crypt isolation method in glands from each tumor from patients with endometrial carcinoma.

METHODS

Twenty-five patients with endometrial adenocarcinoma who underwent surgery were included in this study. We obtained cancerous individual isolated tumor glands from each patient using the crypt isolation method. For LOH and MSI analyses, we used 15 microsatellite markers (3p, 5q, 10q, 13q, 17p, 18q, BAT25, and BAT26) and the promoter regions of 6 genes (transforming growth factor beta receptor II, BAX, insulin-like growth factor II receptor, E2F4, MutS homolog 3, and MSH6).

RESULTS

Loss of heterozygosity was detected in 8 (32%) of 25 patients, and MSI was detected in 9 (36%) of 25 patients. Some MSI-positive carcinomas had LOH in single tumor gland samples, and the coexistence of LOH and MSI was confirmed. In 16 (64%) of 25 cases, intratumoral genetic heterogeneity among single tumor gland samples was detected.

CONCLUSIONS

By analyzing multiple single tumor glands within the same tumor, we found that endometrial adenocarcinoma was composed of various tumor glands with different molecular abnormalities, even in a limited region within the same tumor.

Structural mutation analysis of PTEN and its genotype-phenotype correlations in endometriosis and cancer

The phosphatase and tensin homolog deleted on chromosome ten (PTEN) gene encodes a tumor suppressor phosphatase that has recently been found to be frequently mutated in patients with endometriosis, endometrial cancer and ovarian cancer. Here, we present the first computational analysis of 13 somatic missense PTEN mutations associated with these phenotypes. We found that a majority of the mutations are associated in conserved positions within the active site and are clustered within the signature motif, which contain residues that play a crucial role in loop conformation and are essential for catalysis. In silico analyses were utilized to identify the putative effects of these mutations. In addition, coarse-grained models of both wild-type (WT) PTEN and mutants were constructed using elastic network models to explore the interplay of the structural and global dynamic effects that the mutations have on the relationship between genotype and phenotype. The effects of the mutations reveal that the local structure and interactions affect polarity, protein structure stability, electrostatic surface potential, and global dynamics of the protein. Our results offer new insight into the role in which PTEN missense mutations contribute to the molecular mechanism and genotypic-phenotypic correlation of endometriosis, endometrial cancer, and ovarian cancer. Proteins 2016; 84:1625-1643. © 2016 Wiley Periodicals, Inc.

Differential vimentin expression in ovarian and uterine corpus endometrioid adenocarcinomas: diagnostic utility in distinguishing double primaries from metastatic tumors

This study aimed to assess the diagnostic value of vimentin expression in differentiating endometrioid adenocarcinoma of primary uterine corpus and ovarian origin. Immunohistochemical analyses for the expression of vimentin in tumoral epithelial cells were performed on 149 endometrioid adenocarcinomas wherein the primary sites were not in question, including whole tissue sections of 27 carcinomas of uterine corpus origin (and no synchronous ovarian tumor), 7 carcinomas of ovarian origin (and no synchronous uterine corpus tumor) and a tissue microarray (TMA) containing 91 primary uterine corpus and 24 primary ovarian carcinomas. We also assessed 15 cases that synchronously involved the uterine corpus and ovary, 15 cases of metastasis to organs/tissues other than uterine corpus or ovary as well as 7 lymph node metastases. Vimentin was negative in 97% (30/31) of primary ovarian carcinomas. In contrast, 82% (97/118) of primary uterine corpus carcinomas were vimentin-positive. Vimentin expression was discordant in 53% of synchronous tumors. The sensitivity and specificity of negative vimentin staining in predicting an ovarian primary were 97% and 82%, respectively, whereas parallel values for positive vimentin staining in predicting a primary uterine tumor were 82% and 97%, respectively. The pattern of vimentin expression in all cases was maintained in their respective regional lymph nodes and distant metastases. In conclusion, ovarian and uterine corpus endometrioid adenocarcinomas have different patterns of vimentin expression. If validated in larger and/or different data sets, these findings may have diagnostic value in distinguishing metastatic lesions from double primary tumors involving both sites.

4-hydroxy estrogen induces DNA damage on codon 130/131 of PTEN in endometrial carcinoma cells

Catechol estrogens, such as 4-hydroxyestradiol (4-OHE2), are estrogen metabolites that form DNA adducts and may induce mutations and subsequent cell transformation in mammary cells; however, little is known about their roles in endometrial carcinogenesis. Furthermore, it remains unclear whether 4-OHE2 is able to induce DNA damage on specific genes involved in carcinogenesis or a 'pro'-mutation status such as microsatellite instability (MSI). Therefore, we modified terminal transferase-dependent PCR by the application of a capillary sequencer to detect DNA damage at the single base level. Using this method, we demonstrated that 4-OHE2 directly induced DNA damage on codon 130/131 in exon 5 of PTEN, which is a mutation hot spot for PTEN in endometrial carcinoma. Whereas, both estradiol and 4-OHE2 treatment did not affect MSI status in immortalized endometrial glandular cells. 4-OHE2 might contribute to endometrial carcinogenesis by inducing PTEN mutation on codon 130/131.

Modeling glands with PTEN deficient cells and microscopic methods for assessing PTEN loss: endometrial cancer as a model

PTEN is an important tumor suppressor gene. Interpreting PTEN deficiency in the appropriate microscopic context of cancer may be important to understand its role in tumor development and progression. This may be particularly relevant in heterogeneous tumors. Here, we discuss the usefulness of 3D cultures in understanding the consequences of PTEN inactivation in tissue architecture. Afterwards, we discuss the role of immunohistochemistry and fluorescent in situ hybridization in assessing PTEN loss in tumors. In this review, endometrial carcinoma is used as a model.

Immunohistochemical characterization of endometrial carcinomas: endometrioid, serous and clear cell adenocarcinomas in association with genetic analysis

Developments in immunohistochemistry, which are closely linked with the advances in the analyses of genetic abnormalities and their associated molecular disorders as early and late histogenetic events, have contributed greatly to the improvement of pathological diagnostic confirmation and validation. Immunohistochemistry has also generated great benefit to the innovation of therapeutic strategies for various kinds of cancers. In this article, the three representative histological types of corpus cancer, namely, endometrioid adenocarcinoma, serous adenocarcinoma and clear cell adenocarcinoma, will be histologically approached in association with their immunohistochemical profiles as well as genetic disorders. First, the focus will be on 'Conventional/prototypic features,' followed by 'Controversy over conventional histological subclassification,' and subsequently 'Tumorigenesis and re-subclassification'.

Pathologic scoring of PTEN immunohistochemistry in endometrial carcinoma is highly reproducible

Endometrial carcinomas show frequent PTEN-PI3K pathway abnormalities, and there are currently multiple trials focused on PI3K pathway inhibitors in patients with endometrial carcinoma. PTEN immunohistochemistry may help to select patients with potential for response to targeted therapy, making it important to develop and validate this stain in formalin-fixed, paraffin-embedded tissue. Immunohistochemistry for PTEN was performed and scored independently on 118 cases of endometrial carcinomas from 2 cancer centers using monoclonal DAKO 6H2.1 antibody. Cases were scored as positive, negative, or heterogeneous; reproducibility of PTEN staining and interpretation was assessed. Overall interobserver agreement was good (weighted κ=0.80), with 82% concordance, similar for nonendometrioid (81%) and endometrioid carcinomas (85%). Twenty-one of 118 cases showed discrepant results (17%) that resulted from differences in interpretation and not staining. Our study shows that evaluation of PTEN loss by immunohistochemistry is highly reproducible with the application of standard immunohistochemical techniques and simple scoring criteria.

Inferring primary tumor sites from mutation spectra: a meta-analysis of histology-specific aberrations in cancer-derived cell lines

Next-generation sequencing technologies have led to profound characterization of mutation spectra for several cancer types. Hence, we sought to systematically compare genomic aberrations between primary tumors and cancer lines. For this, we compiled publically available sequencing data of 1651 genes across 905 cell lines. We used them to characterize 23 distinct primary tumor sites by a novel approach that is based on Bayesian spam-filtering techniques. Thereby, we confirmed the strong overall similarity of alterations between patient samples and cell culture. However, we also identified several suspicious mutations, which had not been associated with their cancer types before. Based on these characterizations, we developed the inferring cancer origins from mutation spectra (ICOMS) tool. On our cell line collection, the algorithm reached a prediction specificity rate of 79%, which strongly variegated between primary cancer sites. On an independent validation cohort of 431 primary tumor samples, we observed a similar accuracy of 71%. Additionally, we found that ICOMS could be employed to deduce further attributes from mutation spectra, including sub-histology and compound sensitivity. Thus, thorough classification of site-specific mutation spectra for cell lines may decipher further genome-phenotype associations in cancer.

Relationship between PTEN, DNA mismatch repair, and tumor histotype in endometrial carcinoma: retained positive expression of PTEN preferentially identifies sporadic non-endometrioid carcinomas

Loss of PTEN (phosphatase and tensin homolog) expression and microsatellite instability are two of the more common molecular alterations in endometrial carcinoma. From the published literature, it is controversial as to whether there is a relationship between these different molecular mechanisms. Therefore, a cohort of 187 pure endometrioid and non-endometrioid endometrial carcinomas, carefully characterized as to clinical and pathological features, was examined for PTEN sequence abnormalities and the immunohistochemical expression of PTEN and the DNA mismatch repair proteins MLH1, MSH2, MSH6, and PMS2. MLH1 methylation analysis was performed when tumors had loss of MLH1 protein. Mismatch repair protein loss was more frequent in endometrioid carcinomas compared with non-endometrioid carcinomas, a difference primarily attributable to the presence of MLH1 methylation in a greater proportion of endometrioid tumors. Among the non-endometrioid group, mixed endometrioid/non-endometrioid carcinomas were the histotype that most commonly had loss of a mismatch repair protein. In endometrioid tumors, the frequency of PTEN loss measured by immunohistochemistry and mutation did not differ significantly between the mismatch repair protein intact or mismatch repair protein loss groups, suggesting that PTEN loss is independent of mismatch protein repair status in this group. However, in non-endometrioid carcinomas, both intact positive PTEN immunohistochemical expression and PTEN wild type were highly associated with retained positive expression of mismatch repair proteins in the tumor. Relevant to screening endometrial cancers for Lynch Syndrome, an initial PTEN immunohistochemistry determination may be able to replace the use of four mismatch repair immunohistochemical markers in 63% of patients with non-endometrioid endometrial carcinoma. Therefore, PTEN immunohistochemistry, in combination with tumor histotype, is a useful adjunct in the clinical evaluation of endometrial carcinomas for Lynch Syndrome.

Molecular pathology of endometrial carcinoma

This review paper discusses the main molecular alterations of endometrial carcinoma, the most common cancer of the female genital tract. Two clinicopathological variants are recognized: the oestrogen-related (type I, endometrioid carcinoma) and the non-oestrogen-related (type II, non-endometrioid carcinoma). Whereas type I shows microsatellite instability and mutations in PTEN, PIK3CA, K-RAS and CTNNB1 (beta-catenin), type II exhibits TP53 mutations and chromosomal instability. Recent investigations regarding the role of non-coding RNA have provided important information regarding tumour progression. Understanding pathogenesis at the molecular level is essential for identifying biomarkers of potential use in targeted therapies.

Primary squamous cell carcinoma of the endometrium unrelated to human papilloma virus: a molecular study

In this paper we report a molecular study of a case of Primary Endometrial Squamous Carcinoma (PESC), in which a Human Papilloma Virus (HPV) infection had been previously excluded by Polymerase Chain Reaction (PCR). The studies performed in an effort to explain the carcinogenesis included immunohistochemical over-expression of p53 and p16 proteins as previously observed in our own papers, plus microsatellite analysis of D10S1765 at 10q23.3 (PTEN) and TP53 at 17p13.1 (P53) as well as the methylation status of the of BRCA1 and p16 promoters using specific PCRs. In this rare malignancy, we found allelic imbalance (AI) at 17p13.1 (P53). Instead, AI at D10S1765 (PTEN) gene was absent. The genetic alteration of p53, with hyper-expression of p53 protein and an absence of abnormalities in the PTEN gene are consistent with the similarities between Uterine Serous Carcinoma (USC) and our case of PESC. The aberrant methylation of both p16 and BCAR1 promoters was not detected in our case. This finding too could imply that ESC is more similar to Uterine Serous Carcinoma than Uterine Endometrioid Carcinoma (UEC). Moreover, the lack of aberrant methylation of p16, which is in accordance with over-expression of p16 immunoreactivity, in the absence of HPV infection may be related to other unknown genetic alterations. In our opinion, it is hard to reach any definite conclusion concerning the carcinogenesis of PESC, because of its rarity and the very few molecular studies reported in the literature. Further studies with more numerous cases and larger molecular analyses are mandatory for this malignancy, to confirm whether it is more closely related to papillary endometrial cancer than to endometrioid carcinoma.

Application of Immunohistochemistry and Molecular Diagnostics to Clinically Relevant Problems in Endometrial Cancer Bojana Djordjevic, Shannon Westin, Russell R. Broaddus

A number of different clinical scenarios are presented in which lab-based analyses beyond the usual diagnosis based on light microscopic examination of H&E stained slides - immunohistochemistry and PCR-based assays such as sequencing, mutation testing, microsatellite instability analysis, and determination of MLH1 methylation - are most helpful for guiding diagnosis and treatment of endometrial cancer. The central goal of this information is to provide a practical guide of key current and emerging issues in diagnostic endometrial cancer pathology that require the use of ancillary laboratory techniques, such as immunohistochemistry and molecular testing. The authors present the common diagnostic problems in endometrial carcinoma pathology, types of endometrial carcinoma, description of tissue testing and markers, pathological features, and targeted therapy.

Clinical assessment of PTEN loss in endometrial carcinoma: immunohistochemistry outperforms gene sequencing

PTEN (phosphatase and tensin homolog) is a tumor suppressor that negatively regulates the PI3K-AKT signaling pathway, which is implicated in the pathogenesis of endometrial carcinoma. Sanger sequencing has been considered to be the gold standard for detection of PTEN sequence abnormalities. However, this approach fails to address the epigenetic mechanisms that contribute to functional PTEN loss. Using a study cohort of 154 endometrioid and non-endometrioid endometrial carcinomas, we performed full-length PTEN sequencing and PTEN immunohistochemistry on each tumor. PTEN sequence abnormalities were detected in a significantly lower proportion of cases (43%) than PTEN protein loss (64%, P=0.0004). Endometrioid tumors had a significantly higher proportion of PTEN sequence abnormalities and PTEN protein loss than non-endometrioid tumors. Within the latter group, PTEN sequence abnormalities and PTEN protein loss were most frequent in undifferentiated carcinomas, followed by mixed carcinomas; they were least frequent in carcinosarcomas. Overall, at least one PTEN sequence abnormality was detected in each exon, and the greatest number of sequence abnormalities was detected in exon 8. Pure-endometrioid tumors had a significantly higher frequency of sequence abnormalities in exon 7 than did the non-endometrioid tumors (P=0.0199). Importantly, no mutational hotspots were identified. While PTEN protein loss by immunohistochemistry was identified in 89% of cases with a PTEN sequence abnormality, PTEN protein loss was detected by immunohistochemistry in 44% of cases classified as PTEN wild type by sequencing. For the first time, we demonstrate that PTEN immunohistochemistry is able to identify the majority of cases with functional PTEN loss. However, PTEN immunohistochemistry also detects additional cases with PTEN protein loss that would otherwise be undetected by gene sequencing. Therefore, for clinical purposes, immunohistochemistry appears to be a preferable technique for identifying endometrial tumors with loss of PTEN function.

Increased signalling of EGFR and IGF1R, and deregulation of PTEN/PI3K/Akt pathway are related with trastuzumab resistance in HER2 breast carcinomas

Background:

Trastuzumab resistance hampers its well-known efficacy to control HER2-positive breast cancer. The involvement of PI3K/Akt pathway in this mechanism is still not definitively confirmed.

Methods:

We selected 155 patients treated with trastuzumab after development of metastasis or as adjuvant/neoadjuvant therapy. We performed immunohistochemistry for HER2, ER/PR, epidermal growth factor 1-receptor (EGFR), α-insulin-like growth factor 1-receptor (IGF1R), phosphatase and tensin homologue (PTEN), p110α, pAkt, pBad, pmTOR, pMAPK, MUC1, Ki67, p53 and p27; mutational analysis of PIK3CA and PTEN, and PTEN promoter hypermethylation.

Results:

We found 46% ER/PR-positive tumours, overexpression of EGFR (15%), α-IGF1R (25%), p110α (19%), pAkt (28%), pBad (22%), pmTOR (23%), pMAPK (24%), MUC1 (80%), PTEN loss (20%), and PTEN promoter hypermethylation (20%). PIK3CA and PTEN mutations were detected in 17% and 26% tumours, respectively. Patients receiving adjuvant trastuzumab with α-IGF1R or pBad overexpressing tumours presented shorter progression-free survival (PFS) (all P⩽0.043). Also, p110α and mTOR overexpression, liver and brain relapses implied poor overall survival (OS) (all P⩽0.041). In patients with metastatic disease, decreased PFS correlated with p110α expression (P=0.024), whereas for OS were the presence of vascular invasion and EGFR expression (P⩽0.019; Cox analysis).

Conclusion:

Our results support that trastuzumab resistance mechanisms are related with deregulation of PTEN/PI3K/Akt/mTOR pathway, and/or EGFR and IGF1R overexpression in a subset of HER2-positive breast carcinomas.

Endometrial carcinoma: molecular alterations involved in tumor development and progression

In the western world, endometrial carcinoma (EC) is the most common cancer of the female genital tract. The annual incidence has been estimated at 10-20 per 100,000 women. Two clinicopathological variants are recognized: the estrogen related (type I, endometrioid) and the non-estrogen related (type II, non-endometrioid).The clinicopathological differences are paralleled by specific genetic alterations, with type I showing microsatellite instability and mutations in phosphatase and tensin homologue deleted on chromosome 10, PIK3CA, K-RAS and CTNNB1 (β-catenin), and type II exhibiting TP53 mutations and chromosomal instability. Some non-endometrioid carcinomas probably arise from pre-existing endometrioid carcinomas as a result of tumor progression and, not surprisingly, some tumors exhibit combined or mixed features at the clinical, pathological and molecular levels. In EC, apoptosis resistance may have a role in tumor progression. Understanding pathogenesis at the molecular level is essential in identifying biomarkers for successful targeted therapies. In this review, the genetic changes of endometrial carcinogenesis are discussed in the light of the morphological features of the tumors and their precursors.

ERα-mediated repression of pro-inflammatory cytokine expression by glucocorticoids reveals a crucial role for TNFα and IL1α in lumen formation and maintenance

Most glandular tissues comprise polarized epithelial cells organized around a single central lumen. Although there is active research investigating the molecular networks involved in the regulation of lumenogenesis, little is known about the extracellular factors that influence lumen formation and maintenance. Using a three-dimensional culture system of epithelial endometrial cells, we have revealed a new role for pro-inflammatory cytokines such as TNFα and IL1α in the formation and, more importantly, maintenance of a single central lumen. We also studied the mechanism by which glucocorticoids repress TNFα and IL1α expression. Interestingly, regulation of pro-inflammatory cytokine expression and subsequent lumen formation is mediated by estrogen receptor α (ERα) but not by the glucocorticoid receptor. Finally, we investigated the signaling pathways involved in the regulation of lumen formation by pro-inflammatory cytokines. Our results demonstrate that activation of the ERK/MAPK signaling pathway, but not the PI3K/Akt signaling pathway, is important for the formation and maintenance of a single central lumen. In summary, our results suggest a novel role for ERα-regulated pro-inflammatory cytokine expression in lumen formation and maintenance.

Coexisting atypical polypoid adenomyoma and endometrioid endometrial carcinoma in a young woman with Cowden Syndrome: Case report and implications for screening and prevention

► Cowden Syndrome is a rare hereditary cancer syndrome, which confers an increased risk of breast, thyroid, endometrial and colon cancer. ► Atypical polypoid adenomyoma does not generally represent a premalignant lesion, but must be carefully screened for foci of malignancy. ► Cancer screening must be intensified for patients who meet the diagnostic criteria for Cowden Syndrome.

Strategies for distinguishing low-grade endometrioid and serous carcinomas of endometrium

Distinction between endometrioid and serous carcinomas of the endometrium has important prognostic and therapeutic implications. Misdiagnosing a serous carcinoma as endometrioid can have significant consequences for the patient and pathologist. Although many cases are straightforward and easy to classify, there are occasional problematic cases. This review focuses on strategies that help differentiate between low-grade endometrioid carcinoma and serous carcinoma of the endometrium. We will discuss clinical, morphologic, and immunohistochemical differences between the 2 entities and provide practical tips for practicing pathologists when confronted with this differential diagnosis.

Personalized therapy in endometrial cancer: challenges and opportunities

Early stage endometrial cancer is generally curable. However, progress in the treatment of advanced and recurrent endometrial cancer has been limited. This has led to a shift from the use of traditional chemotherapeutic agents and radiotherapy regimens to the promising area of targeted therapy, given the large number of druggable molecular alterations found in endometrial cancer. To maximize the effects of directed targeted therapy, careful molecular characterization of the endometrial tumor is necessary. This represents an important difference in the use of targeted therapy vs. traditional chemotherapy or radiation treatment. This review will discuss relevant pathways to target in endometrial cancer as well as the challenges that arise during development of a personalized oncology approach.

FGFR2 alterations in endometrial carcinoma

Fibroblast growth factor receptor 2 (FGFR2) is a tyrosine kinase receptor involved in many biological processes such as embryogenesis, adult tissue homeostasis and cell proliferation. Mutations in FGFR2 have been reported in up to 10-12% of endometrial carcinomas identical to those found in congenital craniofacial disorders. Inhibition of FGFR2 could be a new therapeutic target in endometrial carcinoma. FGFR2 immunostaining was assessed in three tissue microarrays: one constructed from paraffin-embedded blocks of 60 samples of normal endometrium in different phases of menstrual cycle, and two tissue microarrays containing endometrial carcinoma samples (95 and 62 cases). FGFR2 expression was correlated with stage, histological type and grade as well as with immunostaining of PTEN, RASSF1A, estrogen and progesterone receptors, KI67, Cyclin D1, STAT-3 and SPRY2. FGFR2 mutations were assessed by PCR and direct sequencing, with DNA obtained from 31 paraffin-embedded endometrial carcinoma samples. In normal endometrium, FGFR2 expression was higher in the secretory than in the proliferative phase (P=0.001), with an inverse correlation with Ki67 (P=0.00032), suggesting a tumor-suppressor role for FGFR2 in normal endometrium. Cytoplasmic expression of FGFR2 was higher in endometrial carcinoma when compared with the atrophic endometrium from the same patients (P=0.0283), but was lower in comparison with normal endometrium from women in the menstrual cycle. Interestingly, nuclear staining was observed in some cases, and it was less frequent in endometrial carcinoma when compared with the adjacent atrophic endometrium (P=0.0465). There were no statistical differences when comparing superficial and myoinvasive endometrial carcinoma samples. Endometrioid endometrial carcinomas showed higher expression of FGFR2 than nonendometrioid endometrial carcinomas (fold change 2.56; P=0.0015). Grade III endometrioid endometrial carcinomas showed decreased FGFR2 expression when compared with grade II endometrioid endometrial carcinomas (P=0.0055). No differences were found regarding pathological stage. Two missense mutations of FGFR2 gene were detected in exons 6 and 11 (S252W and N549K, respectively; 6.45%). Results support the hypothesis that FGFR2 has a dual role in the endometrium, by inhibiting cell proliferation in normal endometrium during the menstrual cycle, but acting as an oncogene in endometrial carcinoma.

Endometrial carcinomas: a review emphasizing overlapping and distinctive morphological and immunohistochemical features

This review focuses on the most common diagnostic pitfalls and helpful morphologic and immunohistochemical markers in the differential diagnosis between the different subtypes of endometrial carcinomas, including: (1) endometrioid versus serous glandular carcinoma, (2) papillary endometrioid (not otherwise specified, villoglandular and nonvillous variants) versus serous carcinoma, (3) endometrioid carcinoma with spindle cells, hyalinization, and heterologous components versus malignant mixed müllerian tumor, (4) high-grade endometrioid versus serous carcinoma, (5) high-grade endometrioid carcinoma versus dedifferentiated or undifferentiated carcinoma, (6) endometrioid carcinoma with clear cells versus clear cell carcinoma, (7) clear cell versus serous carcinoma, (8) undifferentiated versus neuroendocrine carcinoma, (9) carcinoma of mixed cell types versus carcinoma with ambiguous features or variant morphology, (10) Lynch syndrome-related endometrial carcinomas, (11) high-grade or undifferentiated carcinoma versus nonepithelial uterine tumors. As carcinomas in the endometrium are not always primary, this review also discusses the differential diagnosis between endometrial carcinomas and other gynecological malignancies such as endocervical (glandular) and ovarian/peritoneal serous carcinoma, as well as with extra-gynecologic metastases (mainly breast and colon).

Phase II study of temsirolimus in women with recurrent or metastatic endometrial cancer: a trial of the NCIC Clinical Trials Group

PURPOSE

Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene, and loss of function mutations are common and appear to be important in the pathogenesis of endometrial carcinomas. Loss of PTEN causes deregulated phosphatidylinositol-3 kinase/serine-threonine kinase/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling which may provide neoplastic cells with a selective survival advantage by enhancing angiogenesis, protein translation, and cell cycle progression. Temsirolimus, an ester derivative of rapamycin that inhibits mTOR, was evaluated in this setting.

PATIENTS AND METHODS

Sequential phase II studies evaluated single-agent activity of temsirolimus in women with recurrent or metastatic chemotherapy-naive or chemotherapy-treated endometrial cancer. Temsirolimus 25 mg intravenously was administered weekly in 4-week cycles.

RESULTS

In the chemotherapy-naive group, 33 patients received a median of four cycles (range, one to 23 cycles). Of the 29 patients evaluable for response, four (14%) had an independently confirmed partial response and 20 (69%) had stable disease as best response, with a median duration of 5.1 months (range, 3.7 to 18.4 months) and 9.7 months (range, 2.1 to 14.6 months). Only five patients (18%) had progressive disease. In the chemotherapy-treated group, 27 patients received a median of three cycles (range, one to six cycles). Of the 25 patients evaluable for response, one (4%) had an independently confirmed partial response, and 12 patients (48%) had stable disease, with a median duration of 4.3 months (range, 3.6 to 4.9 months) and 3.7 months (range, 2.4 to 23.2 months). PTEN loss (immunohistochemistry and mutational analysis) and molecular markers of PI3K/Akt/mTOR pathway did not correlate with the clinical outcome.

CONCLUSION

mTOR inhibition with temsirolimus has encouraging single-agent activity in endometrial cancer which is higher in chemotherapy-naive patients than in chemotherapy-treated patients and is independent of PTEN status. The difference in activity according to prior therapy should be factored into future clinical trial designs.

Adenovirus mediated homozygous endometrial epithelial Pten deletion results in aggressive endometrial carcinoma

Pten is the most frequently mutated gene in uterine endometriod carcinoma (UEC) and its precursor complex atypical hyperplasia (CAH). Because the mutation frequency is similar in CAH and UEC, Pten mutations are thought to occur relatively early in endometrial tumorigenesis. Previous work from our laboratory using the Pten(+/-) mouse model has demonstrated somatic inactivation of the wild type allele of Pten in both CAH and UEC. In the present study, we injected adenoviruses expressing Cre into the uterine lumen of adult Pten floxed mice in an attempt to somatically delete both alleles of Pten specifically in the endometrium. Our results demonstrate that biallelic inactivation of Pten results in an increased incidence of carcinoma as compared to the Pten(+/-) mouse model. In addition, the carcinomas were more aggressive with extension beyond the uterus into adjacent tissues and were associated with decreased expression of nuclear ERα as compared to associated CAH. Primary cultures of epithelial and stromal cells were prepared from uteri of Pten floxed mice and Pten was deleted in vitro using Cre expressing adenovirus. Pten deletion was evident in both the epithelial and stromal cells and the treatment of the primary cultures with estrogen had different effects on Akt activation as well as Cyclin D3 expression in the two purified components. This study demonstrates that somatic biallelic inactivation of Pten in endometrial epithelium in vivo results in an increased incidence and aggressiveness of endometrial carcinoma compared to mice carrying a germline deletion of one allele and provides an important in vivo and in vitro model system for understanding the genetic underpinnings of endometrial carcinoma.

Selected Topics in the Molecular Pathology of Endometrial Carcinoma

In the developed world, endometrial carcinoma is the most common malignant tumor of the female gynecologic tract. Numerous epidemiologic studies indicate that exposure to unopposed estrogen is a significant risk factor for developing endometrial cancer, particularly endometrioid-type endometrial carcinoma; however, a number of other molecular pathways and mechanisms are also important in endometrial cancer. In this review, the authors highlight some of the more interesting molecular pathways in endometrial cancer, such as the PTEN/PI3K/AKT pathway, microsatellite instability, and molecular mediators of epithelial-to-mesenchymal transition.

IMP3 distinguishes uterine serous carcinoma from endometrial endometrioid adenocarcinoma

Differentiating uterine serous carcinoma (USC) from endometrioid adenocarcinoma (EAC) could be problematic, especially in high-grade EACs and tumors exhibiting architectural variations. To address this issue, we evaluated 103 endometrial carcinoma cases using 4 immunomarkers, beta-catenin, IMP3, PTEN, and p53. Cases included 31 USCs, 57 EACs, and 15 mixed EAC-USCs. Of 31 USCs and 57 EACs, 8 and 9, respectively, were considered diagnostically difficult and challenging. beta-catenin was more frequently expressed in EAC (P = .001); p53, PTEN, and IMP3 were more frequently found in USC (P < .001 for each). IMP3 was the best independent predictive marker for USCs. The best marker combination for predicting USCs was PTEN+/IMP3+ (exact odds ratio, 163.87; 95% confidence interval, 19.62 to infinity; P < .001). IMP3 was consistently negative in all 9 challenging EAC cases and consistently positive in all 8 challenging USC cases. None of the markers or their combinations demonstrated any value in making the diagnosis of serous component in mixed EAC-USC tumors. IMP3 immunoexpression and the IMP3+/PTEN+ pattern are the best independent and combination markers, respectively, to predict USCs. We strongly recommend using them in difficult and challenging cases.

Expression profiling of 22 genes involved in the PI3K-AKT pathway identifies two subgroups of high-grade endometrial carcinomas with different molecular alterations

Previously, we showed that PIK3CA and p53 alterations in uterine endometrial carcinomas correlate with poor prognosis. However, the contribution of phosphatidylinositol 3-kinase (PI3K) -AKT deregulation to endometrial carcinogenesis is not completely understood. The purpose of this study was to analyze alterations of this pathway in endometrial carcinomas and correlate them with the most common genetic abnormalities. Expression profiling of 22 genes involved in PI3K-AKT signaling pathway was analyzed in 38 endometrial carcinomas using TaqMan low-density array (TLDA) analysis. The gene expression pattern was analyzed by hierarchical clustering analysis. Unsupervised clustering divided the high-grade endometrial carcinomas into two clusters. One cluster identified tumors with alterations in the PI3K-AKT signaling pathway (exon 20 PIK3CA mutations and/or PTEN mutations 9/15; 60%), and p16 protein overexpression (8/13; 62%). Almost all non-endometrioid adenocarcinomas (serous and clear cell adenocarcinomas) were segregated into this cluster. In contrast, the other cluster identified tumors with p53 alterations (6/6; 100%), p16 protein overexpression (5/5; 100%), and exon 9 PIK3CA mutations (2/6; 33%). Exon 20 PIK3CA and PTEN mutations were not found in this subgroup. Low-grade endometrial carcinomas clustered in a third subgroup characterized by high frequency of PTEN mutations (10/17; 59%) and microsatellite instability (6/17; 35%). Our results show that gene expression profile differences in the PI3K-AKT signaling pathway identify two subgroups of high-grade endometrial carcinomas with different molecular alterations (PI3K-AKT pathway vs p53 alterations) that may have distinct roles in endometrial carcinogenesis. Identification of these subgroups can provide insight into the biology of these tumors and may facilitate the development of future treatments.