hMLH1 promoter hypermethylation is an early event in human endometrial tumorigenesis

Fluorimetric detection of DNA methylation by cerium oxide nanoparticles for early cancer diagnosis

In this study, a very sensitive fluorescence nano-biosensor was developed using CeO2 nanoparticles for the rapid detection of DNA methylation. The characteristics of CeO2 nanoparticles were determined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) spectroscopy, UV-visible spectroscopy, and fluorescence spectroscopy. The CeO2 nanoparticles were reacted with a single-stranded DNA (ssDNA) probe, and then methylated and unmethylated target DNAs hybridized with an ssDNA probe, and the fluorescence emission was measured. Upon adding the target unmethylated and methylated ssDNA, the fluorescence intensity increased in the linear range of concentration from 2 × 10-13 - 10-18 M. The limit of detection (LOD) was 1.597 × 10-6 M for methylated DNA and 1.043 × 10-6 M for unmethylated DNA. The fluorescence emission intensity of methylated sequences was higher than of that unmethylated sequences. The fabricated DNA nanobiosensor showed a fluorescence emission at 420 nm with an excitation wavelength of 280 nm. The impact of CeO2 binding on methylated and unmethylated DNA was further demonstrated by agarose gel electrophoresis. Finally, the actual sample analysis suggested that the nanobiosensor could have practical applications for detecting methylation in the human plasma samples.

MLH1-methylated endometrial cancer under 60 years of age as the "sentinel" cancer in female carriers of high-risk constitutional MLH1 epimutation

OBJECTIVE

Universal screening of endometrial carcinoma (EC) for mismatch repair deficiency (MMRd) and Lynch syndrome uses presence of MLH1 methylation to omit common sporadic cases from follow-up germline testing. However, this overlooks rare cases with high-risk constitutional MLH1 methylation (epimutation), a poorly-recognized mechanism that predisposes to Lynch-type cancers with MLH1 methylation. We aimed to determine the role and frequency of constitutional MLH1 methylation among EC cases with MMRd, MLH1-methylated tumors.

METHODS

We screened blood for constitutional MLH1 methylation using pyrosequencing and real-time methylation-specific PCR in patients with MMRd, MLH1-methylated EC ascertained from (i) cancer clinics (n = 4, <60 years), and (ii) two population-based cohorts; "Columbus-area" (n = 68, all ages) and "Ohio Colorectal Cancer Prevention Initiative (OCCPI)" (n = 24, <60 years).

RESULTS

Constitutional MLH1 methylation was identified in three out of four patients diagnosed between 36 and 59 years from cancer clinics. Two had mono-/hemiallelic epimutation (∼50% alleles methylated). One with multiple primaries had low-level mosaicism in normal tissues and somatic "second-hits" affecting the unmethylated allele in all tumors, demonstrating causation. In the population-based cohorts, all 68 cases from the Columbus-area cohort were negative and low-level mosaic constitutional MLH1 methylation was identified in one patient aged 36 years out of 24 from the OCCPI cohort, representing one of six (∼17%) patients <50 years and one of 45 patients (∼2%) <60 years in the combined cohorts. EC was the first/dual-first cancer in three patients with underlying constitutional MLH1 methylation.

CONCLUSIONS

A correct diagnosis at first presentation of cancer is important as it will significantly alter clinical management. Screening for constitutional MLH1 methylation is warranted in patients with early-onset EC or synchronous/metachronous tumors (any age) displaying MLH1 methylation.

Excavation of Molecular Subtypes of Endometrial Cancer Based on DNA Methylation

Tumor heterogeneity makes the diagnosis and treatment of endometrial cancer difficult. As an important modulator of gene expression, DNA methylation can affect tumor heterogeneity and, therefore, provide effective information for clinical treatment. In this study, we explored specific prognostic clusters based on 482 examples of endometrial cancer methylation data in the TCGA database. By analyzing 4870 CpG clusters, we distinguished three clusters with different prognostics. Differences in DNA methylation levels are associated with differences in age, grade, clinical pathological staging, and prognosis. Subsequently, we screened out 264 specific hypermethylation and hypomethylation sites and constructed a prognostic model for Bayesian network classification, which corresponded to the classification of the test set to the classification results of the train set. Since the tumor microenvironment plays a key role in determining immunotherapy responses, we conducted relevant analyses based on clusters separated from DNA methylation data to determine the immune function of each cluster. We also predicted their sensitivity to chemotherapy drugs. Specific classifications of DNA methylation may help to address the heterogeneity of previously existing molecular clusters of endometrial cancer, as well as to develop more effective, individualized treatments.

Research Progress of DNA Methylation in Endometrial Cancer

Endometrial cancer (EC)) is one of the most common malignant tumors of the female genital system, with an increasing incidence and mortality, worldwide. Although the therapeutic strategy of EC is still complicated and challenging, further understanding of carcinogenesis from a gene perspective would allow an effort to improve therapeutic precision in this complex malignancy. DNA methylation is the most widely studied epigenetic alteration in human tumors. Aberrant DNA methylation events, resulting in altered gene expression, are features of many tumor types. In this review, we provide an update on evidence about the roles of aberrant DNA methylation within some classical tumor suppressor genes and oncogenes in endometrial carcinogenesis, and report on recent advances in the understanding of the contribution of aberrant DNA methylation to EC, as well as opportunities and challenges of DNA methylation in EC management and prevention.

Improving the Diagnosis of Endometrial Hyperplasia Using Computerized Analysis and Immunohistochemical Biomarkers

Endometrial hyperplasia (EH) is a precursor lesion to endometrial carcinoma (EC). Risks for EC include genetic, hormonal and metabolic factors most notably those associated with obesity: rates are rising and there is concern that cases in pre-menopausal women may remain undetected. Making an accurate distinction between benign and pre-malignant disease is both a challenge for the pathologist and important to the gynecologist who wants to deliver the most appropriate care to meet the needs of the patient. Premalignant change may be recognized by histological changes of endometrial hyperplasia (which may occur with or without atypia) and endometrial intraepithelial neoplasia (EIN). In this study we created a tissue resource of EH samples diagnosed between 2004 and 2009 (n = 125) and used this to address key questions: 1. Are the EIN/WHO2014 diagnostic criteria able to consistently identify premalignant endometrium? 2. Can computer aided image analysis inform identification of EIN? 3. Can we improve diagnosis by incorporating analysis of protein expression using immunohistochemistry. Our findings confirmed the inclusion of EIN in diagnostic criteria resulted in a better agreement between expert pathologists compared with the previous WHO94 criteria used for the original diagnosis of our sample set. A computer model based on assessment of stromal:epithelial ratio appeared most accurate in classification of areas of tissue without EIN. From an extensive panel of putative endometrial protein tissue biomarkers a score based on assessment of HAND2, PTEN, and PAX2 was able to identify four clusters one of which appeared to be more likely to be benign. In summary, our study has highlighted new opportunities to improve diagnosis of pre-malignant disease in endometrium and provide a platform for further research on this important topic.

A tumor association to be aware: endometrial cancer and colon cancer in relation to Lynch syndrome

lynch syndrome (LS) is an autosomal dominant genetic disorder with incomplete penetration caused by a germline mutation in one of the genes of the deoxyribonucleic acid (DNA) mismatch repair system (MMR) namely: mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), mutS homolog 6 (MHS6), post-meiotic segregation increased 1 homolog 2 (PMS2) or the EpCAM (Epithelial CellAdhesionMolecule) gene, which causes the inactivation of MSH2. Patients with this syndrome have a high relative risk of developing cancers at a young age, led by colorectal cancer (CRC) and endometrial cancer in females. The diagnosis is suspected when the patient’s personal and family history meets the Amsterdam or Bethesda criteria. It is guided by immunohistochemistry (IHC) and/or molecular biology that show loss of expression of one or more proteins of the MMR system and microsatellite instability on tumor DNA. In case of positive IHC and/or molecular biology, the patient should be referred to an oncogenetic consultation for a definitive diagnosis. We present the case of a 49-year-old patient who presented an anamic syndrome in metrorrhagia. After a clinical, imaging, biological and anatomopathological examination, the diagnosis of LS was made.

Atypical Endometrial Hyperplasia, Low-grade: "Much ADO About Nothing"

Atypical endometrial hyperplasia (AEH) is considered a precursor of endometrioid carcinoma. The 2020 World Health Organization (WHO) classification divides endometrial hyperplasia into 2 categories: hyperplasia without atypia and atypical hyperplasia/endometrioid intraepithelial neoplasia (EIN); however, this classification does not consider the degree of nuclear atypia. We graded nuclear atypia for estimating the risk of finding carcinoma at hysterectomy. Also, we investigated genes involved in endometrial carcinogenesis including mismatch repair (MMR) genes and ARID1A, PIK3CA, PTEN, KRAS, and CTNNB1. We reviewed 79 biopsies of AEH from 79 patients who underwent hysterectomy within a 1-year interval. Intraobserver and interobserver agreement of grading nuclear atypia and the relationship between the grade of nuclear atypia at biopsy and the findings at hysterectomy were evaluated. Immunohistochemistry for MMR status was performed in all cases and targeted sequencing in 11. Using low-grade versus high-grade nuclear atypia, κ values ranged from 0.74 to 0.91 (89% to 96%) and from 0.72 to 0.81 (87% to 91%) for the intraobserver and the interobserver agreement, respectively. The degree of nuclear atypia at biopsy was highly predictive of the findings at hysterectomy (P=1.6×10-15). Of 53 patients with low-grade AEH, none had carcinoma at hysterectomy, whereas 6 (6/26; 23%) with high-grade AEH in the biopsy also had high-grade AEH in the uterus and 16 (16/26; 61%) had FIGO grade 1 carcinoma. MMR deficiency was found in 3 of the 79 patients. None of the genes showed a mutational load significantly associated with the degree of nuclear atypia. In summary, our data show high reproducibility within and between observers for the diagnosis of low-grade and high-grade AEH. Most cases of AEH had low-grade nuclear atypia and neither high-grade AEH nor carcinoma was encountered in the corresponding hysterectomy specimens.

Discriminating miRNA Profiles between Endometrioid Well- and Poorly-Differentiated Tumours and Endometrioid and Serous Subtypes of Endometrial Cancers

The discrimination of different subtypes of endometrial carcinoma (EC) is frequently problematic when using the current histomorphological classification; therefore, new markers for this differentiation are needed. Here, we examined differences in miRNA expression between well- and poorly-differentiated (grades 1 and 3) endometrioid endometrial carcinoma (EEC) and between EEC and serous endometrial carcinoma (SEC). The expression of 84 tumour-suppressor miRNAs was analysed by real-time polymerase chain reactions in 62 EC and 20 non-neoplastic endometrial specimens. The potential functions of the differentially expressed miRNAs were determined by bioinformatics analyses. The expression of let-7c-5p, miR-125b-5p, miR-23b-3p, and miR-99a-5p in grade 3 EEC was decreased compared to grade 1 EEC. To discriminate between EEC and SEC, let-7g-5p, miR-195-5p, miR-34a-5p, and miR-497-5p expression was significantly downregulated in SEC. In bioinformatic analyses, miRNAs that could discriminate grade 1 from grade 3 mainly targeted genes involved in PI3K-AKT signaling, whereas miRNAs that could discriminate EEC from SEC targeted genes involved in several signaling pathways, but mainly MAPK signaling. Taken collectively, our results indicate that the activation of certain signaling pathways can be useful in the molecular characterization of EEC and SEC.

Prognostic and therapeutic molecular markers in the clinical management of esophageal cancer

Introduction: Esophageal cancer is a deadly disease with high mortality. Treatment with chemotherapy, radiation, and surgery continues to leave many patients with disease progression and recurrence. Novel treatments are needed for this patient population. The development of molecular markers are important for identifying therapeutic targets, as well as prognosis.Areas covered: This review evaluates three molecular markers in esophageal cancer: HER2, PD-L1, and MSI. The fundamentals of these markers, diagnosis, and rates of occurrence in esophageal cancer are explored. The prognostic potential of these markers is based on existing literature as well as application in clinical trials. Key trial findings pertaining to the therapeutic targets for HER2 and PD-1 as well as the role of MSI are discussed.Expert commentary: Molecular markers are changing the practice for esophageal cancer. Therapeutic targeting for HER2 and PD-L1 have shown positive results in recent clinical trials. Trials evaluating immunotherapy as first-line agents are currently underway.

Quantitative next-generation sequencing-based analysis indicates progressive accumulation of microsatellite instability between atypical hyperplasia/endometrial intraepithelial neoplasia and paired endometrioid endometrial carcinoma

Atypical hyperplasia/endometrial intraepithelial neoplasia is an accepted precursor to endometrioid-type endometrial carcinoma. Mismatch repair-deficient endometrial carcinomas are also known to be a biologically and clinically distinct subset of tumors. However, the development of microsatellite instability in endometrial carcinogenesis has not yet been evaluated by novel next-generation sequencing-based methods. We examined 17 mismatch repair-deficient endometrioid endometrial carcinomas and their paired atypical hyperplasia/endometrial intraepithelial neoplasia precursors using a next-generation sequencing panel with quantitative microsatellite instability detection at 336 loci. Findings were compared to histological features, polymerase chain reaction-based microsatellite instability testing, immunohistochemical expression of mismatch repair proteins, and tumor mutational burden calculations. All 17 endometrial carcinomas and 8/17 atypical hyperplasia/endometrial intraepithelial neoplasia showed microsatellite instability by next-generation sequencing-based testing. Endometrial carcinoma specimens showed significantly more unstable microsatellite loci than paired atypical hyperplasia/endometrial intraepithelial neoplasia (mean: 40.0% vs 19.9 unstable loci, respectively). Out of nine microsatellite-stable atypical hyperplasia/endometrial intraepithelial neoplasia specimens, four showed mismatch repair loss by immunohistochemistry. All atypical hyperplasia/endometrial intraepithelial neoplasia and endometrial carcinoma specimens with microsatellite instability were also mismatch repair-deficient by immunohistochemistry. Tumor mutational burden was significantly greater in endometrial carcinoma than in paired atypical hyperplasia/endometrial intraepithelial neoplasia specimens, and tumor mutational burden was significantly correlated with percent unstable microsatellite loci. Paired atypical hyperplasia/endometrial intraepithelial neoplasia and endometrial carcinoma specimens show progressive accumulation of unstable microsatellite loci following loss of mismatch repair protein expression. Comprehensive next-generation sequencing-based testing of endometrial carcinomas offers new insights into endometrial carcinogenesis and opportunities for improved tumor surveillance, diagnosis, and management.

Clinical epigenetics: seizing opportunities for translation

Biomarker discovery and validation are necessary for improving the prediction of clinical outcomes and patient monitoring. Despite considerable interest in biomarker discovery and development, improvements in the range and quality of biomarkers are still needed. The main challenge is how to integrate preclinical data to obtain a reliable biomarker that can be measured with acceptable costs in routine clinical practice. Epigenetic alterations are already being incorporated as valuable candidates in the biomarker field. Furthermore, their reversible nature offers a promising opportunity to ameliorate disease symptoms by using epigenetic-based therapy. Thus, beyond helping to understand disease biology, clinical epigenetics is being incorporated into patient management in oncology, as well as being explored for clinical applicability for other human pathologies such as neurological and infectious diseases and immune system disorders.

New perspectives on screening and early detection of endometrial cancer

Due to the anatomical continuity of the uterine cavity with the cervix, genomic exploitation of material from routine Pap smears and other noninvasive sampling methods represent a unique opportunity to detect signs of disease using biological material shed from the upper genital tract. Recent research findings offer a promising perspective in the detection of endometrial cancer, but certain questions need to be addressed in order to accelerate the implementation of novel technologies in a routine screening or clinical setting. We discuss here new perspectives on detection of endometrial cancer using genomic and other biomarkers in minimally invasive sampling methods with a special focus on public health classic screening criteria, highlighting current gaps in knowledge.

Aberrant expression of genes associated with stemness and cancer in endometria and endometrioma in a subset of women with endometriosis

STUDY QUESTION

Is there molecular evidence for a link between endometriosis and endometriosis-associated ovarian cancers (EAOC)?

STUDY ANSWER

We identified aberrant gene expression signatures associated with malignant transformation in a small subgroup of women with ovarian endometriosis.

WHAT IS KNOWN ALREADY

Epidemiological studies have shown an increased risk of EAOC in women with ovarian endometriosis. However, the cellular and molecular changes leading to EAOC are largely unexplored.

STUDY DESIGN, SIZE, DURATION

CD73+CD90+CD105+ multipotent stem cells/progenitors (SC cohort) were isolated from endometrium (n = 18) and endometrioma (n = 11) of endometriosis patients as well as from the endometrium of healthy women (n = 14). Extensive phenotypic and functional analyses were performed in vitro on expanded multipotent stem cells/progenitors to confirm their altered characteristics. Aberrant gene signatures were also validated in paired-endometrium and -endometrioma tissue samples from another cohort (Tissue cohort, n = 19) of endometriosis patients.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Paired-endometrial and -endometriotic biopsies were obtained from women with endometriosis (ASRM stage III-IV) undergoing laparoscopic surgery. Control endometria were obtained from healthy volunteers. Isolated CD73+CD90+CD105+ SC were evaluated for the presence of known endometrial surface markers, colony forming efficiency, multi-lineage differentiation, cell cycle distribution and 3D-spheroid formation capacity. Targeted RT-PCR arrays, along with hierarchical and multivariate clustering tools, were used to determine both intergroup and intragroup gene expression variability for stem cell and cancer-associated markers, in both SC+ and tissue cohorts.

MAIN RESULTS AND THE ROLE OF CHANCE

Isolated and expanded SC+ from both control and patient groups showed significantly higher surface expression of W5C5+, clonal expansion and 3D-spheroid formation capacity (P < 0.05) compared with SC-. The SC+ cells also undergo mesenchymal lineage differentiation, unlike SC-. Gene expression from paired-endometriosis samples showed significant downregulation of PTEN, ARID1A and TNFα (P < 0.05) in endometrioma compared with paired-endometrium SC+ samples. Hierarchical and multivariate clustering from both SC+ and tissue cohorts together identified 4 out of 30 endometrioma samples with aberrant expression of stem cell and cancer-associated genes, such as KIT, HIF2α and E-cadherin, altered expression ratio of ER-β/ER-α and downregulation of tumour suppressor genes (PTEN and ARID1A). Thus, we speculate that above changes may be potentially relevant to the development of EAOC.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASON FOR CAUTION

As the reported frequency of EAOC is very low, we did not have access to those samples in our study. Moreover, by adopting a targeted gene array approach, we might have missed several other potentially-relevant genes associated with EAOC pathogenesis. The above panel of markers should be further validated in archived tissue samples from women with endometriosis who later in life developed EAOC.

WIDER IMPLICATIONS OF THE FINDINGS

Knowledge gained from this study, with further confirmation on EAOC cases, may help in developing screening methods to identify women with increased risk of EAOC.

STUDY FUNDING/COMPETING INTEREST(S)

The study is funded by the Swedish Research Council (2012-2844), a joint grant from Stockholm County and Karolinska Institutet (ALF), RGD network at Karolinska Institutet, Karolinska Institutet for doctoral education (KID), Estonian Ministry of Education and Research (IUT34-16), Enterprise Estonia (EU48695), Horizon 2020 innovation program (WIDENLIFE, 692065), European Union's FP7 Marie Curie Industry-Academia Partnerships and Pathways funding (IAPP, SARM, EU324509) and MSCA-RISE-2015 project MOMENDO (691058). All authors have no competing interest.

DNA repair in personalized brain cancer therapy with temozolomide and nitrosoureas

Alkylating agents have been used since the 60ties in brain cancer chemotherapy. Their target is the DNA and, although the DNA of normal and cancer cells is damaged unselectively, they exert tumor-specific killing effects because of downregulation of some DNA repair activities in cancer cells. Agents exhibiting methylating properties (temozolomide, procarbazine, dacarbazine, streptozotocine) induce at least 12 different DNA lesions. These are repaired by damage reversal mechanisms involving the alkyltransferase MGMT and the alkB homologous protein ALKBH2, and through base excision repair (BER). There is a strong correlation between the MGMT expression level and therapeutic response in high-grade malignant glioma, supporting the notion that O⁶-methylguanine and, for nitrosoureas, O⁶-chloroethylguanine are the most relevant toxic damages at therapeutically relevant doses. Since MGMT has a significant impact on the outcome of anti-cancer therapy, it is a predictive marker of the effectiveness of methylating anticancer drugs, and clinical trials are underway aimed at assessing the influence of MGMT inhibition on the therapeutic success. Other DNA repair factors involved in methylating drug resistance are mismatch repair, DNA double-strand break (DSB) repair by homologous recombination (HR) and DSB signaling. Base excision repair and ALKBH2 might also contribute to alkylating drug resistance and their downregulation may have an impact on drug sensitivity notably in cells expressing a high amount of MGMT and at high doses of temozolomide, but the importance in a therapeutic setting remains to be shown. MGMT is frequently downregulated in cancer cells (up to 40% in glioblastomas), which is due to CpG promoter methylation. Astrocytoma (grade III) are frequently mutated in isocitrate dehydrogenase (IDH1). These tumors show a surprisingly good therapeutic response. IDH1 mutation has an impact on ALKBH2 activity thus influencing DNA repair. A master switch between survival and death is p53, which often retains transactivation activity (wildtype) in malignant glioma. The role of p53 in regulating survival via DNA repair and the routes of death are discussed and conclusions as to cancer therapeutic options were drawn.

A gene expression assay for simultaneous measurement of microsatellite instability and anti-tumor immune activity

Background

Clinical benefit from checkpoint inhibitors has been associated in a tumor-agnostic manner with two main tumor traits. The first is tumor antigenicity, which is typically measured by tumor mutation burden, microsatellite instability (MSI), or Mismatch Repair Deficiency using gene sequence platforms and/or immunohistochemistry. The second is the presence of a pre-existing adaptive immune response, typically measured by immunohistochemistry (e.g. single analyte PD-L1 expression) and/or gene expression signatures (e.g. tumor “inflamed” phenotype). These two traits have been shown to provide independent predictive information. Here we investigated the potential of using gene expression to predict tumor MSI, thus enabling the measurement of both tumor antigenicity and the level of tumor inflammation in a single assay, possibly reducing sample requirement, turn-around time, and overall cost.

Methods

Using The Cancer Genome Atlas RNA-seq datasets with the greatest MSI-H incidence, i.e. those from colon (n = 208), stomach (n = 269), and endometrial (n = 241) cancers, we trained an algorithm to predict tumor MSI from under-expression of the mismatch repair genes MLH1, PMS2, MSH2, and MSH6 and from 10 additional genes with strong pan-cancer associations with tumor hypermutation. The algorithms were validated on the NanoString nCounter™ platform in independent cohorts of colorectal (n = 52), endometrial (n = 11), and neuroendocrine (n = 4) tumors pre-characterized using the MMR immunohistochemistry assay.

Results

In the validation cohorts, the algorithm showed high prediction accuracy of tumor MSI status, with sensitivity of at least 88% attained at thresholds chosen to achieve 100% specificity. Furthermore, MSI status was compared to the Tumor Inflammation Signature (TIS), an analytically validated diagnostic assay which measures a suppressed adaptive immune response in the tumor and enriches for response to immune checkpoint blockade. TIS score was largely independent of MSI status, suggesting that measuring both parameters may identify more patients that would respond to immune checkpoint blockade than either assay alone.

Conclusions

Development of a gene expression signature of MSI status raises the possibility of a combined diagnostic assay on a single platform which measures both tumor antigenicity and presence of a suppressed adaptive immune response. Such an assay would have significant advantages over multi-platform assays for both ease of use and turnaround time and could lead to a diagnostic test with improved clinical performance.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0472-1) contains supplementary material, which is available to authorized users.

The therapeutic significance of mutational signatures from DNA repair deficiency in cancer

Cancer is fundamentally a disease of the genome and inherited deficiencies in DNA repair pathways are well established to increase lifetime cancer risk. Computational analysis of pan-cancer data has identified signatures of mutational processes thought to be responsible for the pattern of mutations in any given cancer. These analyses identified altered DNA repair pathways in a much broader spectrum of cancers than previously appreciated with significant therapeutic implications. The development of DNA repair deficiency biomarkers is critical to the implementation of therapeutic targeting of repair-deficient tumors, using either DNA damaging agents or immunotherapy for the personalization of cancer therapy.

Targeting DNA repair-deficient tumors is one of the most promising therapeutic strategies in cancer research; however, accurately predicting which tumors will respond can be a challenge. Here the authors present a review of the current state of knowledge in DNA repair deficiency across human cancers.

Inherent and toxicant-provoked reduction in DNA repair capacity: A key mechanism for personalized risk assessment, cancer prevention and intervention, and response to therapy

Genomic investigations reveal novel evidence which indicates that genetic predisposition and inherent drug response are key factors for development of cancer and for poor response to therapy. However, mechanisms for these outcomes and interactions with environmental factors have not been well-characterized. Therefore, cancer risk, prevention, intervention and prognosis determinations have still mainly been based on population, rather than on individualized, evaluations. The objective of this review was to demonstrate that a key mechanism which contributes to the determination is inherent and/or toxicant-provoked reduction in DNA repair capacity. In addition, functional and quantitative determination of DNA repair capacity on an individual basis would dramatically change the evaluation and management of health problems from a population to a personalized basis. In this review, justifications for the scenario were delineated. Topics to be presented include assays for detection of functional DNA repair deficiency, mechanisms for DNA repair defects, toxicant-perturbed DNA repair capacity, epigenetic mechanisms (methylation and miRNA expression) for alteration of DNA repair function, and bioinformatics approach to analyze large amount of genomic data. Information from these topics has recently been and will be used for better understanding of cancer causation and of response to therapeutic interventions. Consequently, innovative genomic- and mechanism-based evidence can be increasingly used to develop more precise cancer risk assessment, and target-specific and personalized medicine.

Diagnostic immunohistochemistry in gynaecological neoplasia: a brief survey of the most common scenarios

Immunohistochemistry is a valuable adjunct in routine gynaecological pathology. The molecular revolution has redesigned knowledge of gynaecological cancers and refined histological classification. The direct consequence has been the progressive introduction of new immunostainings for diagnostic and classification purposes. Hence, we review the routine diagnostic use of immunohistochemistry in the field of gynaecological neoplasia. We reviewed the immunomarkers useful in gynaecological pathology according to literature revision, our personal experience and research findings. We discuss the application of immunohistochemistry to reach the most accurate diagnosis in morphologically equivocal cases of gynaecological pathology and present the appropriate panel of immunomarkers in the most common scenarios of gynaecological pathology. This short review provides an updated overview of the essential immunohistochemical markers currently used in the diagnostics of gynaecological malignancies along with their molecular rationale.

Epigenetic regulation of DNA repair genes and implications for tumor therapy

DNA repair represents the first barrier against genotoxic stress causing metabolic changes, inflammation and cancer. Besides its role in preventing cancer, DNA repair needs also to be considered during cancer treatment with radiation and DNA damaging drugs as it impacts therapy outcome. The DNA repair capacity is mainly governed by the expression level of repair genes. Alterations in the expression of repair genes can occur due to mutations in their coding or promoter region, changes in the expression of transcription factors activating or repressing these genes, and/or epigenetic factors changing histone modifications and CpG promoter methylation or demethylation levels. In this review we provide an overview on the epigenetic regulation of DNA repair genes. We summarize the mechanisms underlying CpG methylation and demethylation, with de novo methyltransferases and DNA repair involved in gain and loss of CpG methylation, respectively. We discuss the role of components of the DNA damage response, p53, PARP-1 and GADD45a on the regulation of the DNA (cytosine-5)-methyltransferase DNMT1, the key enzyme responsible for gene silencing. We stress the relevance of epigenetic silencing of DNA repair genes for tumor formation and tumor therapy. A paradigmatic example is provided by the DNA repair protein O⁶-methylguanine-DNA methyltransferase (MGMT), which is silenced in up to 40% of various cancers through CpG promoter methylation. The CpG methylation status of the MGMT promoter strongly correlates with clinical outcome and, therefore, is used as prognostic marker during glioblastoma therapy. Mismatch repair genes are also subject of epigenetic silencing, which was shown to correlate with colorectal cancer formation. For many other repair genes shown to be epigenetically regulated the clinical outcome is not yet clear. We also address the question of whether genotoxic stress itself can lead to epigenetic alterations of genes encoding proteins involved in the defense against genotoxic stress.

Epigenetic Regulation of ZBTB18 Promotes Glioblastoma Progression

Glioblastoma (GBM) comprises distinct subtypes characterized by their molecular profile. Mesenchymal identity in GBM has been associated with a comparatively unfavorable prognosis, primarily due to inherent resistance of these tumors to current therapies. The identification of molecular determinants of mesenchymal transformation could potentially allow for the discovery of new therapeutic targets. Zinc Finger and BTB Domain Containing 18 (ZBTB18/ZNF238/RP58) is a zinc finger transcriptional repressor with a crucial role in brain development and neuronal differentiation. Here, ZBTB18 is primarily silenced in the mesenchymal subtype of GBM through aberrant promoter methylation. Loss of ZBTB18 contributes to the aggressive phenotype of glioblastoma through regulation of poor prognosis-associated signatures. Restitution of ZBTB18 expression reverses the phenotype and impairs tumor-forming ability. These results indicate that ZBTB18 functions as a tumor suppressor in GBM through the regulation of genes associated with phenotypically aggressive properties.Implications: This study characterizes the role of the putative tumor suppressor ZBTB18 and its regulation by promoter hypermethylation, which appears to be a common mechanism to silence ZBTB18 in the mesenchymal subtype of GBM and provides a new mechanistic opportunity to specifically target this tumor subclass. Mol Cancer Res; 15(8); 998-1011. ©2017 AACR.

Epigenetics in endometrial carcinogenesis - part 1: DNA methylation

Carcinogenesis is a multistep multifactorial process that involves the accumulation of genetic and epigenetic alterations. In the past two decades, there has been an exponential growth of knowledge establishing the importance of epigenetic changes in cancer. Our work focused on reviewing the main role of epigenetics in the pathogenesis of endometrial carcinoma, highlighting the reported results concerning each epigenetic mechanistic layer. The present review is the first part of this work, in which we examined the contribution of DNA methylation alterations for endometrial carcinogenesis.

New concepts for an old problem: the diagnosis of endometrial hyperplasia

BACKGROUND

Endometrial hyperplasia (EH) is a uterine pathology representing a spectrum of morphological endometrial alterations. It is predominantly characterized by an increase in the endometrial gland-to-stroma ratio when compared to normal proliferative endometrium. The clinical significance of EH lies in the associated risk of progression to endometrioid endometrial cancer (EC) and 'atypical' forms of EH are regarded as premalignant lesions. Traditional histopathological classification systems for EH exhibit wide and varying degrees of diagnostic reproducibility and, as a consequence, standardized patient management can be challenging.

OBJECTIVE AND RATIONALE

EC is the most common gynaecological malignancy in developed countries. The incidence of EC is rising, with alarming increases described in the 40-44-year-old age group. This review appraises the current EH classification systems used to stratify women at risk of malignant progression to EC. In addition, we summarize the evidence base regarding the use of immunohistochemical biomarkers for EH and discuss an emerging role for genomic analysis.

SEARCH METHODS

PubMed, Medline and the Cochrane Database were searched for original peer-reviewed primary and review articles, from January 2000 to January 2016. The following search terms were used: 'endometrial hyperplasia', 'endometrial intraepithelial neoplasia', 'atypical hyperplasia', 'complex atypical hyperplasia', 'biomarker', 'immunohistochemistry', 'progression', 'genomic', 'classification' and 'stratification'.

OUTCOMES

Recent changes to EH classification reflect our current understanding of the genesis of endometrioid ECs. The concept of endometrial intraepithelial neoplasia (EIN) as a mutationally activated, monoclonal pre-malignancy represents a fundamental shift from the previously held notion that unopposed oestrogenic stimulation causes ever-increasing hyperplastic proliferation, with accumulating cytological atypia that imperceptibly leads to the development of endometrioid EC. Our review highlights several key biomarker candidates that have been described as both diagnostic tools for EH and markers of progression to EC. We propose that, moving forwards, a 'panel' approach of combinations of the immunohistochemical biomarkers described in this review may be more informative since no single candidate can currently fill the entire role.

WIDER IMPLICATIONS

EC has historically been considered a predominantly postmenopausal disease. Owing in part to the current unprecedented rates of obesity, we are starting to see signs of a shift towards a rising incidence of EC amongst pre- and peri-menopausal woman. This creates unique challenges both diagnostically and therapeutically. Furthering our understanding of the premalignant stages of EC development will allow us to pursue earlier diagnosis and facilitate appropriate stratification of women at risk of developing EC, permitting timely and appropriate therapeutic interventions.

Chemoresistance and targeted therapies in ovarian and endometrial cancers

Gynecological cancers are known for being very aggressive at their advanced stages. Indeed, the survival rate of both ovarian and endometrial cancers is very low when diagnosed lately and the success rate of current chemotherapy regimens is not very efficient. One of the main reasons for this low success rate is the acquired chemoresistance of these cancers during their progression. The mechanisms responsible for this acquired chemoresistance are numerous, including efflux pumps, repair mechanisms, survival pathways (PI3K/AKT, MAPK, EGFR, mTOR, estrogen signaling) and tumor suppressors (P53 and Par-4). To overcome these resistances, a new type of therapy has emerged named targeted therapy. The principle of targeted therapy is simple, taking advantage of changes acquired in malignant cancer cells (receptors, proteins, mechanisms) by using compounds specifically targeting these, thus limiting their action on healthy cells. Targeted therapies are emerging and many clinical trials targeting these pathways, frequently involved in chemoresistance, have been tested on gynecological cancers. Despite some targets being less efficient than expected as mono-therapies, the combination of compounds seems to be the promising avenue. For instance, we demonstrate using ChIP-seq analysis that estrogen downregulate tumor suppressor Par-4 in hormone-dependent cells by directly binding to its DNA regulatory elements and inhibiting estrogen signaling could reinstate Par-4 apoptosis-inducing abilities. This review will focus on the chemoresistance mechanisms and the clinical trials of targeted therapies associated with these, specifically for endometrial and ovarian cancers.

Loss of Mismatch Repair Protein Expression in Unselected Endometrial Adenocarcinoma Precursor Lesions

OBJECTIVE

The benefit of evaluating the precursor of endometrial carcinoma, endometrial hyperplasia (intraepithelial neoplasia [EIN]), for loss of mismatch repair (MMR) protein expression and Lynch syndrome has yet to be determined. The present study aims to establish the incidence and type of loss of MMR protein expression in unselected premalignant lesions of endometrial adenocarcinoma, as well as the agreement of immunohistochemical staining in pretreatment endometrial biopsy (EMB) specimens with subsequent uterine resections.

METHODS

A retrospective review identified 112 endometrial biopsies meeting criteria for endometrial EIN. Slides made from tissue microarray blocks were evaluated using antibodies against MLH1, PMS2, MSH2, and MSH6. Cases with a deficit in MLH1 were evaluated for gene promoter hypermethylation by polymerase chain reaction analysis. Fifty-four subsequent hysterectomy specimens were retrieved and assessed for MMR protein expression.

RESULTS

Of the 112 endometrial biopsies with EIN, 4.5% (5/112) exhibited loss of MMR protein expression. The majority (4/5) demonstrated a deficit of MLH1, of which all exhibited inactivation via promoter hypermethylation. A single case displayed an absence of MSH6. Age was not significantly associated with MMR deficiency. There was no significant association between MMR status in the EMB and a subsequent diagnosis of cancer. Immunohistochemical staining in all successive hysterectomy cases was concordant with the pattern observed in the EMB specimen.

CONCLUSIONS

Sporadic hypermethylation of MLH1 seems to be the primary mechanism underlying defective MMR protein expression in EIN. Among our cohort, only 1 patient (<1%) had a mutation suggestive of a hereditary inheritance. Hence, the utility of evaluating EIN for MMR protein expression as a screen for Lynch syndrome is limited, regardless of age.

Epigenetic therapy in gastrointestinal cancer: the right combination

Epigenetics is a relatively recent field of molecular biology that has arisen over the past 25 years. Cancer is now understood to be a disease of widespread epigenetic dysregulation that interacts extensively with underlying genetic mutations. The development of drugs targeting these processes has rapidly progressed; with several drugs already FDA approved as first-line therapy in hematological malignancies. Gastrointestinal (GI) cancers possess high degrees of epigenetic dysregulation, exemplified by subtypes such as CpG island methylator phenotype (CIMP), and the potential benefit of epigenetic therapy in these cancers is evident. The application of epigenetic drugs in solid tumors, including GI cancers, is just emerging, with increased understanding of the cancer epigenome. In this review, we provide a brief overview of cancer epigenetics and the epigenetic targets of therapy including deoxyribonucleic acid (DNA) methylation, histone modifications, and chromatin remodeling. We discuss the epigenetic drugs currently in use, with a focus on DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, and explain the pharmacokinetic and mechanistic challenges in their application. We present the strategies employed in incorporating these drugs into the treatment of GI cancers, and explain the concept of the cancer stem cell in epigenetic reprogramming and reversal of chemo resistance. We discuss the most promising combination strategies in GI cancers including: (1) epigenetic sensitization to radiotherapy, (2) epigenetic sensitization to cytotoxic chemotherapy, and (3) epigenetic immune modulation and priming for immune therapy. Finally, we present preclinical and clinical trial data employing these strategies thus far in various GI cancers including colorectal, esophageal, gastric, and pancreatic cancer.

Endometriosis-associated Malignancy

Endometriosis is a common condition in women of reproductive age. According to several epidemiological studies endometriosis may be associated with increased risk of various malignancies. However, endometriosis-associated malignancy (EAM) is defined by certain histological criteria. About 80 % of EAM have been found in the ovary, whereas 20 % are localized in extragonadal sites like intestine, rectovaginal septum, abdominal wall, pleura and others. Some authors suggest that EAM arise from atypical endometriosis as an intermediate lesion between endometriosis and cancer. Moreover, a number of genetic alterations, like loss of heterozygosity (LOH), PTEN, ARID1 A and p53 mutations have been found in both endometriosis and EAM. Endometriosis-associated ovarian cancer (EAOC) is mostly a well or intermediately differentiated tumor of endometrioid or clear cell histological sub-type. Women affected by EAOC are on average five to ten years younger than non-EAOC patients; in most of the cases EAOC is a low stage disease with favorable clinical outcome. Since EAM is a rare condition systematic data on EAM are still missing. A systematic retrospective study on endometriosis-associated malignancies (EAM study) is currently being conducted by the Endometriosis Research Foundation together with the study groups on ovarian and uterine tumors of the working group for gynecological oncology (AGO) (gyn@mlk-berlin.de).

DNA methylation analysis of cancer-related genes in oral epithelial cells of healthy smokers

AIM

The aim of this study was to investigate the smoking habit influence on DNA methylation status in the promoters of the cancer related-genes MLH1, hTERT and TP53 in oral epithelial cells of healthy subjects.

MATERIALS AND METHODS

DNA methylation analysis was performed using methylation-sensitive restriction enzymes (MSRE) in oral epithelial cells from non-smokers, smokers and ex-smokers.

RESULTS

The investigated CpG dinucleotides located at HhaI and HpaII sites in the MLH1 gene promoter were observed to be fully methylated in the majority of DNA samples from the smoker group and statistical differences were found between non-smokers and smokers and between smokers and ex-smokers (p<0.05). The same was observed in the hTERT gene promoter at HhaI sites (p<0.05) and for HpaII sites the unmethylated condition was more frequent in smokers in comparison to non-smokers (p<0.05). For TP53, no differences were found among groups (p>0.05), with the fully methylated condition found to be a common event in healthy oral epithelial cells.

CONCLUSION

We conclude that smoking may induce changes in DNA methylation status in cancer-related genes of oral epithelial cells and that the cessation of smoking is capable of reversing this process. Based on our data, we suggest that DNA methylation status of the hTERT and MLH1 gene promoters are promising markers for screening a set of smoking-related alterations in oral cells.

Epigenetic alterations in cancer and personalized cancer treatment

ABSTRACT 

Based on the pivotal importance of epigenetics for transcription regulation, it is not surprising that cancer is characterized by several epigenetic abnormalities. Conversely to genetic alterations, epigenetic changes are not permanent, thus represent opportunities for therapeutic strategies designed to reverse transcriptional abnormalities, and cancer is the first disease in which epigenetic therapies with chromatin remodeling agents were introduced. The role of miRNAs in gene regulation supports their potential as innovative therapeutic strategy. Recent evidences have proven that the environment can profoundly influence the epigenome: diet, smoking and alcohol consumption can negatively impact the expression profile. Given the plasticity of epigenetic marks, it is challenging the idea that the epigenetic alterations are ‘druggable’ sites using specific food components.

Ovarian and endometrial endometrioid adenocarcinomas have distinct profiles of microsatellite instability, PTEN expression, and ARID1A expression

AIMS

To understand the role of and differences in molecular alterations between endometrial and ovarian endometrioid adenocarcinomas.

METHODS AND RESULTS

We investigated the microsatellite status of 26 ovarian endometrioid adenocarcinomas (OVEMs), 42 endometrial endometrioid adenocarcinomas (EMCAs), and 19 concurrent (endometrial and ovarian) endometrioid adenocarcinomas. We evaluated the expression of the mismatch repair proteins, PTEN and ARID1A, and mutations of PTEN, KRAS, CTNNB1, and PIK3CA. High levels of microsatellite instability (MSI-H) were present in one of 26 OVEMs, 12 of 42 EMCAs, and four of 19 concurrent endometrioid adenocarcinomas. Only four of 19 concurrent endometrioid adenocarcinomas showed identical molecular alterations in their endometrial and ovarian components. Loss of ARID1A or loss of PTEN expression, and MSI-H, were more common in EMCAs than OVEMs (P = 0.044, P = 0.004, and P = 0.012, respectively). MSI-H in endometrial endometrioid adenocarcinomas was also related to loss of ARID1A expression (P < 0.001). In the cohort of MSI-H endometrioid adenocarcinomas involving the endometrium (n = 16), MSH6-deficient cases showed higher frequencies of CTNNB1 and PIK3CA mutations (P = 0.008 and P = 0.036, respectively), but lower frequencies of KRAS mutation (P = 0.011), than PMS2-deficient cases.

CONCLUSIONS

The different frequencies of molecular genetic alterations between endometrial endometrioid adenocarcinomas and ovarian endometrioid adenocarcinomas imply that distinct processes may be involved in their tumorigenesis or tumour progression.

Comparative DNA methylome analysis of endometrial carcinoma reveals complex and distinct deregulation of cancer promoters and enhancers

BACKGROUND

Aberrant DNA methylation is a hallmark of many cancers. Classically there are two types of endometrial cancer, endometrioid adenocarcinoma (EAC), or Type I, and uterine papillary serous carcinoma (UPSC), or Type II. However, the whole genome DNA methylation changes in these two classical types of endometrial cancer is still unknown.

RESULTS

Here we described complete genome-wide DNA methylome maps of EAC, UPSC, and normal endometrium by applying a combined strategy of methylated DNA immunoprecipitation sequencing (MeDIP-seq) and methylation-sensitive restriction enzyme digestion sequencing (MRE-seq). We discovered distinct genome-wide DNA methylation patterns in EAC and UPSC: 27,009 and 15,676 recurrent differentially methylated regions (DMRs) were identified respectively, compared with normal endometrium. Over 80% of DMRs were in intergenic and intronic regions. The majority of these DMRs were not interrogated on the commonly used Infinium 450K array platform. Large-scale demethylation of chromosome X was detected in UPSC, accompanied by decreased XIST expression. Importantly, we discovered that the majority of the DMRs harbored promoter or enhancer functions and are specifically associated with genes related to uterine development and disease. Among these, abnormal methylation of transposable elements (TEs) may provide a novel mechanism to deregulate normal endometrium-specific enhancers derived from specific TEs.

CONCLUSIONS

DNA methylation changes are an important signature of endometrial cancer and regulate gene expression by affecting not only proximal promoters but also distal enhancers.

HER2/neu in Endometrial Cancer: A Promising Therapeutic Target With Diagnostic Challenges

CONTEXT

In the era of targeted cancer therapy, there is growing interest in developing novel therapeutic strategies against endometrial carcinoma, especially its most biologically aggressive variant, serous adenocarcinoma. Several publications have demonstrated that a significant proportion of uterine serous carcinomas show HER2 overexpression and/or amplification, suggesting that HER2 may be a promising therapeutic target. Case reports have already shown clinical response to trastuzumab, a humanized monoclonal immunoglobulin (Ig) G1 antibody against HER2, and patients are currently being enrolled in a multi-institutional prospective randomized trial to evaluate the therapeutic efficacy of trastuzumab.

OBJECTIVE

To review current data on HER2 testing and targeted therapy against HER2/neu in endometrial carcinoma.

DATA SOURCES

Review of the literature and personal experience of the authors.

CONCLUSIONS

Parallel to the clinical studies, there is a need to develop standardized criteria for HER2 testing in endometrial carcinoma that reflect the unique biological and pathogenetic features of these tumors and correlate with clinical response to therapy. This article presents a comprehensive review of the current state of HER2-based therapy and HER2 testing in endometrial carcinoma.

Vitamin D and the epigenome

Epigenetic mechanisms play a crucial role in regulating gene expression. The main mechanisms involve methylation of DNA and covalent modifications of histones by methylation, acetylation, phosphorylation, or ubiquitination. The complex interplay of different epigenetic mechanisms is mediated by enzymes acting in the nucleus. Modifications in DNA methylation are performed mainly by DNA methyltransferases (DNMTs) and ten-eleven translocation (TET) proteins, while a plethora of enzymes, such as histone acetyltransferases (HATs), histone deacetylases (HDACs), histone methyltransferases (HMTs), and histone demethylases (HDMs) regulate covalent histone modifications. In many diseases, such as cancer, the epigenetic regulatory system is often disturbed. Vitamin D interacts with the epigenome on multiple levels. Firstly, critical genes in the vitamin D signaling system, such as those coding for vitamin D receptor (VDR) and the enzymes 25-hydroxylase (CYP2R1), 1α-hydroxylase (CYP27B1), and 24-hydroxylase (CYP24A1) have large CpG islands in their promoter regions and therefore can be silenced by DNA methylation. Secondly, VDR protein physically interacts with coactivator and corepressor proteins, which in turn are in contact with chromatin modifiers, such as HATs, HDACs, HMTs, and with chromatin remodelers. Thirdly, a number of genes encoding for chromatin modifiers and remodelers, such as HDMs of the Jumonji C (JmjC)-domain containing proteins and lysine-specific demethylase (LSD) families are primary targets of VDR and its ligands. Finally, there is evidence that certain VDR ligands have DNA demethylating effects. In this review we will discuss regulation of the vitamin D system by epigenetic modifications and how vitamin D contributes to the maintenance of the epigenome, and evaluate its impact in health and disease.

Role of the clinical pathology laboratory in the evaluation of endometrial carcinomas for Lynch syndrome

Molecular diagnostic testing of endometrial carcinomas in the pathology laboratory has recently emerged as a key component of the clinical evaluation of Lynch syndrome in many centers. Testing modalities involve immunohistochemical and PCR-based analyses. This article outlines the routine application of these analyses, provides a practical guide for troubleshooting some of the common technical issues related to their performance, and reviews common pitfalls in their interpretation. Discrepancies between tissue testing and genetic testing results are discussed in the context of the current understanding of endometrial cancer biology. The merits of universal versus targeted tissue testing based on clinical patient history and histological tumor appearance are also addressed.

Epigenetic alterations in sporadic basal cell carcinomas

Basal cell carcinoma (BCC) is the most common malignant human neoplasm characterized by slow growth and virtual absence of metastases. Recently, it has become evident that along with genetic mutations epigenetic alterations play a key role in the pathogenesis of human cancer. We searched for promoter methylation of hMLH1, RASSF1A, DAPK, APC, DCR1 and DCR2 genes and BRAF mutations in BCCs in association with the clinicopathological parameters and the histological subtypes of the tumours. Fifty-two BCCs, 17 FFPE along with 35 fresh tissue samples with matching normal tissues for 26 cases were analyzed by methylation-specific PCR to assess the methylation status of hMLH1, RASSF1A, DAPK, APC, DCR1 and DCR2 genes after sodium bisulfite treatment of the tumour and normal DNA. hMLH1 and DCR1 gene expression was investigated by immunohistochemistry. BRAF mutations were studied by high resolution melting analysis. Methylation was detected at a variable frequency of 44, 33, 32.5, 32 and 14 % of DCR2, APC, DCR1, RASSF1 and DAPK promoters, respectively, whereas methylation of hMLH1 promoter was absent. No BRAF mutations were found. There was no correlation between the frequency of the promoter methylation of the above-mentioned genes and the clinicopathological features or the histological subtypes of the tumours. The relatively high frequency of RASSF1A, DCR1, DCR2 and APC promoter methylation may imply that methylation constitutes an important pathway in the tumourigenesis of BCC that could provide new opportunities in developing epigenetic therapies for BCC patients. Nevertheless, further studies are needed to establish the above-mentioned hypothesis.

The emerging genomic landscape of endometrial cancer

BACKGROUND

Endometrial cancer is responsible for approximately 74 000 deaths annually among women worldwide. It is a heterogeneous disease comprising multiple histologic subtypes. In the US, the majority of deaths from endometrial carcinoma are attributed to the serous and endometrioid subtypes. An understanding of the fundamental genomic alterations that drive serous and endometrioid endometrial carcinomas lays the foundation for the identification of molecular markers that could improve the clinical management of patients presenting with these tumors.

CONTENT

We review the current state of knowledge regarding somatic genomic alterations that occur in serous and endometrioid endometrial tumors. We present this knowledge in a historical context by reviewing the genomic alterations that studies of individual genes and proteins have identified over the past 2 decades or so. We then review very recent comprehensive and systematic surveys of genomic, exomic, transcriptomic, epigenomic, and proteomic alterations in serous and endometrioid endometrial carcinomas.

SUMMARY

The recent mapping of the genomic landscape of serous and endometrioid endometrial carcinomas has produced the first comprehensive molecular classification of these tumors, which has distinguished 4 molecular subgroups: a POLE [polymerase (DNA directed), ε, catalytic subunit] ultramutated subgroup, a hypermutated/microsatellite-unstable subgroup, a copy number-low/microsatellite-stable subgroup, and a copy number-high subgroup. This molecular classification may ultimately serve to refine the diagnosis and treatment of women with endometrioid and serous endometrial tumors.

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.

Sequencing of candidate chromosome instability genes in endometrial cancers reveals somatic mutations in ESCO1, CHTF18, and MRE11A

Most endometrial cancers can be classified histologically as endometrioid, serous, or clear cell. Non-endometrioid endometrial cancers (NEECs; serous and clear cell) are the most clinically aggressive of the three major histotypes and are characterized by aneuploidy, a feature of chromosome instability. The genetic alterations that underlie chromosome instability in endometrial cancer are poorly understood. In the present study, we used Sanger sequencing to search for nucleotide variants in the coding exons and splice junctions of 21 candidate chromosome instability genes, including 19 genes implicated in sister chromatid cohesion, from 24 primary, microsatellite-stable NEECs. Somatic mutations were verified by sequencing matched normal DNAs. We subsequently resequenced mutated genes from 41 additional NEECs as well as 42 endometrioid ECs (EECs). We uncovered nonsynonymous somatic mutations in ESCO1, CHTF18, and MRE11A in, respectively, 3.7% (4 of 107), 1.9% (2 of 107), and 1.9% (2 of 107) of endometrial tumors. Overall, 7.7% (5 of 65) of NEECs and 2.4% (1 of 42) of EECs had somatically mutated one or more of the three genes. A subset of mutations are predicted to impact protein function. The co-occurrence of somatic mutations in ESCO1 and CHTF18 was statistically significant (P = 0.0011, two-tailed Fisher's exact test). This is the first report of somatic mutations within ESCO1 and CHTF18 in endometrial tumors and of MRE11A mutations in microsatellite-stable endometrial tumors. Our findings warrant future studies to determine whether these mutations are driver events that contribute to the pathogenesis of endometrial cancer.

Analysis of the role of hMLH1 hypermethylation and microsatellite instability in meningioma progression

We investigated a possible role of hMLH1 hypermethylation and microsatellite instability in meningioma progression. Fifty meningomas were examined for methylation of hMLH1 using a methylation-specific PCR; 43 of them were analyzed for microsatellite instability using nine microsatellite markers. Loss of heterozygosity on chromosome 22q was detected using two markers. Two atypical meningiomas showed microsatellite instability at four loci; one was methylated on hMLH1 and the other was unmethylated. Nine meningiomas were found to have methylated hMLH1; the frequencies in the different grades of meningioma were one of 20, two of 16, and six of 14, respectively. We concluded that the methylation status of hMLH1 is associated with the meningioma grade but not with microsatellite instability. Loss of heterozygosity was detected in 22 cases in at least one marker. The frequency of loss of heterozygosity increased with meningioma grade, but the tendency was not significant. The correlation between loss of heterozygosity and methylation of the hMLH1 gene was also not significant. We conclude that hypermethylation of the promoter of hMLH1 is an epigenetic change in meningiomas and is associated with the tumor grade, while microsatellite instability is an uncommon event in meningiomas.

Predicting the Coexistence of an Endometrial Adenocarcinoma in the Presence of Atypical Complex Hyperplasia: Immunohistochemical Analysis of Endometrial Samples

Objective

This study aimed to determine whether immunohistochemical markers in complex atypical endometrial hyperplasia could predict the presence of a concurrent endometrial carcinoma.

Methods

Endometrial biopsies of 39 patients with complex atypical hyperplasia were selected retrospectively between 1999 and 2006. Only patients who underwent a hysterectomy were included. A coexisting endometrial carcinoma was present in 25 patients (64%). Immunohistochemical analysis was performed on formalin-fixed paraffin-embedded sections of the endometrial biopsies, using antibodies for MIB-1, β-catenin, E-cadherin, p53, PTEN, CD44, HER2-neu, survivin, COX-2, tenascin, and bcl-2. To evaluate the potential utility of these markers, a prediction model was constructed.

Results

In the univariate analysis, expressions of both PTEN and HER2-neu were significantly different between the groups with and without a coexisting endometrial carcinoma (P < 0.05). Loss of PTEN staining was found in 13 (54%) and 1 (7%) of the patients with and without a coexistent carcinoma, respectively (odds ratio, 16.55; 95% confidence interval [CI], 1.87–146.65). HER2-neu expression was found in only 2 (8.6%) and 6 (43%) patients with and without a coexistent carcinoma, respectively, and was excluded from further analysis because of its low expression. A prediction model containing PTEN expression only showed an area under the curve of 73.4% (95% CI, 57.3%–89.6%). After adding MIB-1 and p53, discriminative power improved to 87.2% (95% CI, 75.1%–99.3%).

Conclusions

This study showed that PTEN expression in complex endometrial hyperplasia is a promising factor for the prediction of the presence of a coexisting endometrial carcinoma, and prediction may even better when MIB-1 and p53 expressions are considered simultaneously.

Molecular links between endometriosis and cancer

Endometriosis is the leading cause of morbidity among premenopausal women affecting about 1 in 10 females. The features shared by endometriosis and cancer include the ability to evade apoptosis, the stem cell-like ability and angiogenic potential. As such characteristics are encoded by the cell's genetic constitution, acquired mutations are responsible for the malignant transformation of endometriosis. Indeed, a number of tumour-suppressor genes and proto-oncogenes, such as protein 53 (P53) and B-cell lymphoma 2 (BCL-2) respectively, are mutated and as a result differentially expressed between endometriotic and malignant tissue associated with endometriosis. Moreover, cytokines and macrophages, both of which are inflammatory mediators have been implicated in the transformation process. The angiogenic properties possessed by cancer arising from endometriosis signifies a bad prognosis, while the stem cell-like activity possessed by both endometriosis and cancer has been attributed to the effect of oestrogen. A number of differences between endometriosis and cancer are found at the molecular level. Considering the link between these two pathologies, the three components which fuel the malignant transformation of endometriosis can be embodied in the endometriosis-induced carcinoma (EIC) triangle which shows the intricate relationship between endocrinologic, immunologic and genetic components.

14-3-3σ mediates G2-M arrest produced by 5-aza-2'-deoxycytidine and possesses a tumor suppressor role in endometrial carcinoma cells

OBJECTIVES

To determine the effect of 5-aza-2'-deoxycytidine (DAC) on human endometrial carcinoma cell (HECC) oncogenicity and demonstrate a molecular mechanism by which DAC modulates HECC oncogenicity.

METHODS

The effect of DAC was tested on HECC RL95-2, AN3, Ishikawa and ECC1 cells. The role of 14-3-3σ on HECC oncogenicity in response to DAC treatment was evaluated in RL95-2 and AN3 cells after forced expression or silencing of 14-3-3σ gene expression.

RESULTS

Treatment of HECC with DAC produced non-cytotoxic cell growth inhibition and G2/M cell cycle arrest. This effect was strongly correlated with increased expression of p21 and 14-3-3σ. Silencing of 14-3-3σ induced cellular proliferation and reduced the effect of DAC on cell cycle arrest in G2/M phases. Conversely, forced expression of 14-3-3σ showed the opposite effect. Furthermore, forced expression of 14-3-3σ in human endometrial cell lines reduced cell growth and colony formation.

CONCLUSIONS

We suggest that 14-3-3σ in HECC suppresses cell proliferation and mediates DAC induced G2/M arrest and inhibition of cell proliferation in HECC.