Molecular pathology of endometrial carcinoma: transcriptional signature in endometrioid tumors

A dualistic model, which has been established on a morphological basis and that differentiates type I endometrioid from type II non-endometrioid endometrial cancer, is widely accepted. Molecular genetics have provided us with data supporting the dualistic model of endometrial tumorigenesis and with some clues to speculate about the sequence of the molecular alterations defining the tumorigenesis pathways. In type I endometrioid endometrial cancer, PTEN gene silencing, microsatellite instability associated with defects in DNA mismatch repair genes, or mutations in the K-ras gene are the known major alterations defining the progression from normal endometrium to hyperplasia and then on to carcinoma. Recently, cDNA microarray technology for identifying the differences in gene expression patterns between the histological types of endometrial cancer have permitted the identification of differentially expressed genes that could help us to understand differences in the biology and the clinical outcome between histiotypes. Genes involved in the mitotic checkpoint as a major mechanism of carcinogenesis in non-endometrioid endometrial cancer, or altered genes associated with the initial steps of myometrial infiltration in endometrioid endometrial cancer, represent examples of how useful large genetic screenings can be for understanding the tumorigenesis process and the future directions in the molecular pathogenesis of endometrial cancer.     

Endometrial cancer

Endometrial cancer is the most common gynaecological malignancy in the developed world. The majority of cases can be divided into two broad categories based on clinico-pathological and molecular characteristics; Type I oestrogen-dependent with endometrioid morphology and Type II non-oestrogen-dependent with serous papillary or clear cell morphology. As has been described for other malignancies, such as colorectal carcinoma, the transition from normal endometrium to carcinoma is thought to involve a stepwise accumulation of alterations in cellular regulatory pathways leading to dysfunctional cell growth. This article reviews the current knowledge of the molecular changes commonly associated with endometrial cancer and presents possible progression models.     

Ⅰ型子宫内膜癌组织中HIF-1α、Snail与E-cadherin的表达及临床意义

目的探讨I型子宫内膜癌组织中HIF-1α的表达,以及调控Snail和E-cadherin对肿瘤侵袭性生物学行为的影响。方法采用免疫组化方法,结合组织芯片技术,检测124例I型子宫内膜癌、28例内膜不典型增生、35例正常内膜组织中HIF-1α、Snail和E-cadherin的表达水平,分析三种蛋白表达之间的相关性及与临床病理因素的关系。结果 I型子宫内膜癌组织中HIF-1α、Snail和E-cadherin的表达率分别为61.3%、46.8%、36.3%,与正常内膜和不典型增生内膜组织相比,有显著统计学差异(P<0.01)。HIF-1α表达与病理分级、肿瘤肌层浸润和淋巴结转移明显相关(P<0.05)。Snail表达与FIGO分期、淋巴结转移明显相关(P<0.05)。E-cadherin的缺失与肿瘤肌层浸润和淋巴结转移显著相关(P<0.01)。I型子宫内膜癌组织中HIF-1α和Snail的表达呈明显正相关(r=0.214,P=0.017),而Snail和E-cadherin的表达存在负相关关系(r=–0.203,P=0.024)。结论 HIF-1α可能通过上调Snail的表达和抑制E-cadherin的表达在I型子宫内膜癌发生、侵袭和转移中发挥重要作用。     

New insights on the pathogenesis of ovarian carcinoma: molecular basis and clinical implications

Ovarian carcinoma can be subdivided into two categories termed type I and type II. Type I tumours, usually having an indolent clinical behaviour, are often detected in early stage, and rarely harbour p53 gene mutations. Each histological type has a distinct molecular profile with mutations of genes involved in different signalling transduction pathways, such as KRAS, BRAF, CTNNB1, PTEN, PIK3CA and ARID1A. Type II tumours, accounting for 75% of the cases, have a very aggressive biological behaviour, are usually in advanced stage at presentation, harbour p53 gene mutations in 80% of the cases, and sometimes have alterations of homologous recombination (HR). Both type I and type II tumours arise from extra-ovarian precursors. Serous carcinomas derive from tubal epithelium, endometrioid and clear cell carcinomas from endometrial tissue, and mucinous and Brenner tumours from transitional epithelial cells located near the tubo-peritoneal junction. These new concepts on the pathogenesis of ovarian carcinoma could deeply modify both the preventive approach in women with germ-line BRCA(1) or BRCA(2) mutations and the treatment of patients with advanced or recurrent disease. For instance, BRAF inhibitors could be used in low-grade serous carcinomas, PIK3CA inhibitors could be employed in clear cell carcinoma, and poly (ADP-ribose) polymerase inhibitors could be used not only in hereditary ovarian carcinoma but also in non-hereditary, high-grade serous ovarian carcinoma which sometimes shows defective HR.     

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.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-868) contains supplementary material, which is available to authorized users.     

An approach to early genetic alterations in precancerous cells

To investigate the potential role of the PTEN tumor-suppressor gene in the carcinogenesis of ovarian endometrioid carcinoma and its related subtype, clear cell carcinoma, we examined 20 ovarian endometrioid carcinomas, 24 clear cell carcinomas and 34 solitary endometrial cysts of the ovary for LOH at 10q23.3 and point mutations of the PTEN gene, using a laser-assisted microdissection method. LOH was found in 8 of 19 ovarian endometrioid carcinomas (42.1%), 6 of 22 clear cell carcinomas (27.3%) and 13 of 23 solitary endometrial cysts (56.5%). Somatic mutations in the PTEN gene were identified in 4 of 20 ovarian endometrioid carcinomas (20.0%), 2 of 24 clear cell carcinomas (8.3%) and 7 of 34 solitary endometrial cysts (20.6%). In 5 endometrioid carcinomas with endometriosis, 3 displayed LOH events common to both the carcinoma and the endometriosis. In 7 clear cell carcinomas with endometriosis, 3 displayed LOH events common to both the carcinoma and the endometriosis. In no cases there were LOH events in the endometriosis only. These results indicate that inactivation of the PTEN gene is an early event in the development of both endometrioid and clear cell carcinoma of the ovary. A laser-assisted microdissection method enables us to collect target cells without contamination by non-tumor cells. We expect that this technique will be very useful for investigating genetic alterations in cancerous or precancerous lesions. Early genetic alterations in various precancerous cells detected by light microscopy can be readily identified by the tissue-microdissection method.     

Biomarkers as prognostic factors in endometrial cancer

Endometrial cancer is the most common gynecologic malignancy in more developed countries. Approximately 75% of cases are diagnosed at an early stage with a tumor confined to the uterine corpus. Although most patients are cured by surgery alone, about 15-20% with no signs of locally advanced or metastatic disease at primary treatment recurs, with limited responsiveness to systemic therapy. The most common basis for determining the risk of recurrent disease has been classification of endometrial cancers into two subtypes. Type I, associated with a good prognosis and endometrioid histology and type II, associated with a poor prognosis and non-endometrioid histology. This review will focus primarily on the molecular biomarkers that have supported the dualistic model of endometrial carcinoma and help determine which patients would benefit from either adjuvant therapy or more aggressive primary treatment.     

Aromatase and comparative response to its inhibitors in two types of endometrial cancer

Aromatase activity (AA) was evaluated totally in 80 tumors collected from primary endometrial cancer (EC) patients. All patients were divided into cases belonging to the types I or II of EC (respectively, 50 and 30 observations). Samples of malignant endometrium from type II demonstrated inclination to the higher AA in comparison with type I samples; the difference reached level of statistical significance in non-smoking patients (p = 0.02). Although no positive correlation was revealed between AA in EC tissue and percentage of cells with DNA damage in normal endometrium from the same patients, the rate of DNA damage (percent of comets, comet's tail average length, etc.) was higher in intact endometrium collected from patients with type II of the disease. In 19 tumor samples, CYP19 gene expression was evaluated by RT-PCR and level of mRNA signal demonstrated positive correlation with AA (R_s = +0.63, p = 0.05) in the whole this material. Of note, though, CYP19 mRNA expression was not revealed in six cases, and all of them belonged to the type I of disease. Finally, in 23 EC patients (15 with type I and 8 with type II of the disease) effects of 2 weeks treatment with letrozole (10 pts) and exemestane (13 pts) were evaluated in neoadjuvant setting. Although diminishing of endometrial M-echo signal and the increases in FSH and LH concentration after treatment were more pronounced in type I patients, decrease in tumor PR content (p = 0.04) was more revealing in patients with type II of EC; besides, the decreases in AA in tumor tissue by the end of treatment were noted predominantly in patients with lower body weight (BMI <27.5). Thus, although type II of EC is frequently considered as hormone-independent, increased ability of this type of the tumor to estrogen biosynthesis (at CYP19 gene and protein level) may lead to the reconsideration of such conclusion and warrants further investigation. The search of possible ethnic differences in AA and in the biologic response to aromatase inhibitors in EC can be of importance too.     

Repression of endometrial tumor growth by targeting SREBP1 and lipogenesis

The aberrantly increased lipogenesis is a universal metabolic feature of proliferating tumor cells. Although most normal cells acquire the bulk of their fatty acids from circulation, tumor cells synthesize more than 90% of required lipids de novo. The sterol regulatory element-binding protein 1 (SREBP1), encoded by SREBF1 gene, is a master regulator of lipogenic gene expression. SREBP1 and its target genes are overexpressed in a variety of cancers; however, the role of SREBP1 in endometrial cancer is largely unknown. We have screened a cohort of endometrial cancer (EC) specimen for their lipogenic gene expression and observed a significant increase of SREBP1 target gene expression in cancer cells compared with normal endometrium. By using immunohistochemical staining, we confirmed SREBP1 protein overexpression and demonstrated increased nuclear distribution of SREBP1 in EC. In addition, we found that knockdown of SREBP1 expression in EC cells suppressed cell growth, reduced colonigenic capacity and slowed tumor growth in vivo. Furthermore, we observed that knockdown of SREBP1 induced significant cell death in cultured EC cells. Taken together, our results show that SREBP1 is essential for EC cell growth both in vitro and in vivo, suggesting that SREBP1 activity may be a novel therapeutic target for endometrial cancers.     

Repression of endometrial tumor growth by targeting SREBP1 and lipogenesis

The aberrantly increased lipogenesis is a universal metabolic feature of proliferating tumor cells. Although most normal cells acquire the bulk of their fatty acids from circulation, tumor cells synthesize more than 90% of required lipids de novo. The sterol regulatory element-binding protein 1 (SREBP1), encoded by SREBF1 gene, is a master regulator of lipogenic gene expression. SREBP1 and its target genes are overexpressed in a variety of cancers; however, the role of SREBP1 in endometrial cancer is largely unknown. We have screened a cohort of endometrial cancer (EC) specimen for their lipogenic gene expression and observed a significant increase of SREBP1 target gene expression in cancer cells compared with normal endometrium. By using immunohistochemical staining, we confirmed SREBP1 protein overexpression and demonstrated increased nuclear distribution of SREBP1 in EC. In addition, we found that knockdown of SREBP1 expression in EC cells suppressed cell growth, reduced colonigenic capacity and slowed tumor growth in vivo. Furthermore, we observed that knockdown of SREBP1 induced significant cell death in cultured EC cells. Taken together, our results show that SREBP1 is essential for EC cell growth both in vitro and in vivo, suggesting that SREBP1 activity may be a novel therapeutic target for endometrial cancers.     

Oestrogen receptor‐mediated expression of Olfactomedin 4 regulates the progression of endometrial adenocarcinoma

Endometrial adenocarcinoma is the most common tumour of the female genital tract in developed countries, and oestrogen receptor (ER) signalling plays a pivotal role in its pathogenesis. When we used bioinformatics tools to search for the genes contributing to gynecological cancers, the expression of Olfactomedin 4 (OLFM4) was found by digital differential display to be associated with differentiation of endometrial adenocarcinoma. Aberrant expression of OLFM4 has been primarily reported in tumours of the digestive system. The mechanism of OLFM4 in tumuorigenesis is elusive. We investigated OLFM4 expression in endometrium, analysed the association of OLFM4 with ER signalling in endometrial adenocarcinoma, and examined the roles of OLFM4 in endometrial adenocarcinoma. Expression of OLFM4 was increased during endometrial carcinogenesis, linked to the differentiation of endometrioid adenocarcinoma, and positively related to the expression of oestrogen receptor‐α (ERα) and progesterone receptor. Moreover, ERα‐mediated signalling regulated expression of OLFM4, and knockdown of OLFM4 enhanced proliferation, migration and invasion of endometrial carcinoma cells. Down‐regulation of OLFM4 was associated with decreased cumulative survival rate of patients with endometrioid adenocarcinoma. Our data suggested that impairment of ERα signal‐mediated OLFM4 expression promoted the malignant progression of endometrioid adenocarcinoma, which may have significance for the therapy of this carcinoma.     

Carcinoma of the Lower Uterine Segment (LUS): Clinicopathological Characteristics and Association with Lynch Syndrome

Endometrial cancer arises from the uterine body and fundus in many cases, but can also originate from the lower region of the uterine body through the upper region of the cervix. Such tumors are referred to as carcinoma of the lower uterine segment (LUS) or isthmus, and account for 3-6.3% of all cases of endometrial cancer. This relatively low incidence has permitted performance of only small-scale studies, but the clinical and pathological characteristics of carcinoma of the LUS in all these reports have differed from those of other endometrial cancers. Generally, endometrial cancer is classified into estrogen-dependent endometrioid adenocarcinoma (designated as type I), and non-endometrioid types that are less associated with estrogen and include poorly differentiated adenocarcinoma (type II). In some reports, carcinoma of the LUS has been found to have type II characteristics. Carcinoma of the LUS has also been associated with Lynch syndrome, a hereditary disease with frequent development of colorectal, endometrial, and ovarian cancers. Lynch syndrome is thought to be induced by mismatch repair gene mutation. The frequency of Lynch syndrome in cases of general endometrial cancer is 1-2%. In contrast, the frequency in patients with carcinoma of the LUS is much higher, with up to 29% of cases diagnosable with Lynch syndrome and a high frequency of hMSH2 mutation found in one study. This suggests that further investigation of the clinical and pathological characteristics of carcinoma of the LUS and the association with Lynch syndrome is required through performance of a large-scale survey.     

子宫内膜癌发生分子机制研究进展

子宫内膜癌（Endometrial cancer,EC）是子宫内膜上皮的恶性肿瘤,可分为I型EC和II型EC。最近的分子遗传学证据表明EC是由基因表达异常改变及突变引起的,例如I型EC中常伴随着pten、k-mS、ctnnbl（β-CATENIN）、mnx、etv5／erm、hgf／met、cyr16等基因的异常;II型EC通常与p53、erbb2（her2／neu）等基因异常有关,这些异常包括基因突变、缺失、扩增、过量表达等。本文就其相关分子机制的研究进展进行综述。     

子宫内膜癌组织中生长抑素受体、VEGF的表达及其与血管形成的关系

目的探讨生长抑素受体（somatostatin receptor,SSTR）、血管内皮生长因子（vascular endothelial growth factor,VEGF）在子宫内膜癌组织中的表达及其与肿瘤血管形成的关系。方法应用免疫组织化学方法检测60例子宫内膜癌组织中SSTR各亚型、VEGF及CD34标记的微血管密度（microvessel denisity,MVD）的表达情况,探讨其与子宫内膜癌临床病理学特征及肿瘤血管形成的关系。结果在60例子宫内膜癌组织中,SSTR各亚型（SSTR1、SSTR2、SSTR3、SSTR4及SSTR5）的阳性表达率分别为70．0％,15．0％。21．7％,23．3％及18．3％;SSTR3、SSTR4在中高分化组表达阳性率明显高于低分化组（P〈0．05）。VEGF的阳性表达率为83．3％,VEGF在低分化组表达阳性率明显高于中高分化组、深肌层浸润组表达阳性率明显高于浅肌层浸润组、FIGO分期≥II期组表达阳性率明显高于I期组（P〈0．05）。子宫内膜癌组MVD（44．85±15．78）明显高于正常子宫内膜组MVD（18．96±4．30）（P〈0．01）。SSTR5的表达与VEGF呈负相关,VEGF阳性表达组子宫内膜癌组织MVD高于VEGF阴性组。结论联合检测SSTR和VEGF对子宫内膜癌预后的评估有一定临床意义。生长抑素类似物（somatostatin analogs,SSTA）可能为子宫内膜癌的诊治提供新的靶点。     

凋亡抑制蛋白Survivin在增生性子宫内膜及子宫内膜癌中的表达

目的　研究凋亡抑制蛋白Survivin在正常子宫内膜、增生性子宫内膜及子宫内膜癌中的表达 ,探讨Survivin蛋白在子宫内膜癌发生发展中的作用及其作为预后判断因子的可行性。方法　应用免疫组织化学S P法 ,检测 15例正常子宫内膜、 2 6例增生性子宫内膜及 33例子宫内膜腺癌中Survivin蛋白的表达 ,并结合临床病理特点进行分析。结果　Sur vivin蛋白的阳性表达率在正常子宫内膜 ,增生性子宫内膜及子宫内膜癌中呈上升趋势。正常子宫内膜仅在增生期有微弱的表达 ,而分泌期及绝经期子宫内膜表达全为阴性 ;而Survivin在子宫内膜癌中及不典型增生中的阳性表达率分别为87 88%和 70 0 % ,均明显高于正常内膜 (P <0 0 5 ) ,且两者的过表达率均高于单纯和复合型增生及正常内膜 (P <0 0 5 ) ,但子宫内膜癌中与不典型增生中的Survivin表达率及过表达率均无明显差异。子宫内膜癌中Survivin的表达强度与组织学分级及手术病理分期明显相关 (P <0 0 5 ) ,但与肌层浸润无关。结论　Survivin作为凋亡相关因子和细胞周期调节因子 ,可能参与了与子宫内膜癌的发生发展 ,其过度表达与预后不良相关 ,其检测可为子宫内膜癌的早期诊断、辅助治疗及预后判断提供理论依据。     

Serum levels of VEGF and VEGF-C in patients with endometrial cancer

Endometrial cancer (EC) is the most common type of uterine cancer. A dualistic model of endometrial tumorigenesis serves as a useful way of categorizing these cancers in terms of both etiology and clinical behavior. There are two types of EC: type I and type II. Type I is so-called estrogen-dependent, and appears mostly in pre- and perimenopausal women, it is well differentiated and therefore has a better prognosis. Type II EC is estrogen-independent, diagnosed mostly in postmenopausal women, thin and fertile women, or in women with normal menstrual cycles. It is aggressive and has a worse prognosis than type I. The aim of this study was to evaluate the relationship between the pretreatment serum levels of VEGF and VEGF-C and the outcome of EC patients. A total of 98 patients treated between 1999 and 2003 were included in this study. Circulating VEGF and VEGF-C levels were determined using ELISA kits. VEGF levels among the 76 patients with type I, and the 22 patients with type II EC were significantly higher than those found in the healthy control subjects (p?相似文献