Nuclear size distinguishes low- from high-grade ovarian serous carcinoma and predicts outcome

A dualistic model for ovarian serous carcinogenesis based on morphological and molecular genetic studies has recently been proposed. This model divides serous carcinoma into low- and high-grade tumors, which develop along distinct molecular pathways. In this report, we evaluated computerized morphometry to determine its utility in distinguishing low- and high-grade serous carcinoma. The mean nuclear area (MNA) and the volume percentage of epithelium (VPE) in 93 high-grade serous carcinomas was measured and compared with 16 low-grade serous carcinomas and 21 serous borderline tumors, the putative precursor of low-grade serous carcinoma. We found that both MNA and VPE were significantly higher in high-grade serous carcinoma compared with low-grade serous carcinoma and serous borderline tumors (P < .001 and P = .02, respectively). There was no significant difference in MNA and VPE between low-grade carcinoma and serous borderline tumors (P > .3). Among high-grade serous carcinomas, those with an MNA of 46 microm2 or higher had a poorer survival (P = .035) than those with an MNA below 46 microm2. In contrast, VPE and tumor grade (moderately versus poorly differentiated) had no significant prognostic value. The morphometry findings lend further support to the dualistic model of ovarian serous carcinogenesis and suggest that MNA is an excellent adjunctive tool for distinguishing low- from high-grade serous carcinomas. In addition, MNA is an independent prognostic factor for high-grade serous carcinoma.     

Ovarian tumorigenesis: a proposed model based on morphological and molecular genetic analysis

The pathogenesis of ovarian carcinoma, the most lethal gynecological malignancy, is unknown because of the lack of a tumor progression model. Based on a review of recent clinicopathological and molecular studies, we propose a model for their development. In this model, surface epithelial tumors are divided into two broad categories designated type I and type II tumors that correspond to two main pathways of tumorigenesis. Type I tumors tend to be low-grade neoplasms that arise in a stepwise manner from borderline tumors whereas type II tumors are high-grade neoplasms for which morphologically recognizable precursor lesions have not been identified, so-called de novo development. As serous tumors are the most common surface epithelial tumors, low-grade serous carcinoma is the prototypic type I tumor and high-grade serous carcinoma is the prototypic type II tumor. In addition to low-grade serous carcinomas, type I tumors are composed of mucinous carcinomas, endometrioid carcinomas, malignant Brenner tumors, and clear cell carcinomas. Type I tumors are associated with distinct molecular changes that are rarely found in type II tumors, such as BRAF and KRAS mutations for serous tumors, KRAS mutations for mucinous tumors, and beta-catenin and PTEN mutations and microsatellite instability for endometrioid tumors. Type II tumors include high-grade serous carcinoma, malignant mixed mesodermal tumors (carcinosarcoma), and undifferentiated carcinoma. There are very limited data on the molecular alterations associated with type II tumors except frequent p53 mutations in high-grade serous carcinomas and malignant mixed mesodermal tumors (carcinosarcomas). This model of carcinogenesis reconciles the relationship of borderline tumors to invasive carcinoma and provides a morphological and molecular framework for studies aimed at elucidating the pathogenesis of ovarian cancer.     

In ovarian neoplasms, BRAF, but not KRAS, mutations are restricted to low-grade serous tumours

Genes of the RAF family, which mediate cellular responses to growth signals, encode kinases that are regulated by RAS and participate in the RAS/RAF/MEK/ERK/MAP-kinase pathway. Activating mutations in BRAF have recently been identified in melanomas, colorectal cancers, and thyroid and ovarian tumours. In the present study, an extensive characterization of BRAF and KRAS mutations has been performed in 264 epithelial and non-epithelial ovarian neoplasms. The epithelial tumours ranged from adenomas and borderline neoplasms to invasive carcinomas including serous, mucinous, clear cell, and endometrioid lesions. It is shown that BRAF mutations in ovarian tumours occur exclusively in low-grade serous neoplasms (33 of 91, 36%); these included serous borderline tumours (typical and micropapillary variants), an invasive micropapillary carcinoma and a psammocarcinoma. KRAS mutations were identified in 26 of 91 (29.5%) low-grade serous tumours, 7 of 49 (12%) high-grade serous carcinomas, 2 of 6 mucinous adenomas, 22 of 28 mucinous borderline tumours, and 10 of 18 mucinous carcinomas. Of note, two serous borderline tumours were found to harbour both BRAF and KRAS mutations. The finding that at least 60% of serous borderline tumours harbour mutations in two members of the ERK-MAP-kinase pathway (BRAF 36%, KRAS 30%) compared with 12% of high-grade serous carcinomas (BRAF 0%, KRAS 12%) indicates that the majority of serous borderline tumours do not progress to serous carcinomas. Furthermore, no BRAF mutations were detected in the other 173 ovarian tumours in this study.     

Inhibitory role of prohibitin in human ovarian epithelial cancer

Objectives: To characterize the exact individual roles of gonadotropins on ovarian epithelial carcinogenesis, an earlier study showed that prohibitin was significantly up-regulated by luteinizing hormone (LH). To further clarify the role of prohibitin in ovarian carcinogenesis and its association with LH, herein we studied the expression of prohibitin in various ovarian tissues including different developmental stages of ovarian epithelial tumors. Methods: A total of 135 samples were studied by immunohistochemistry. These included benign ovarian cases with follicles, ovarian surface epithelia and ovarian epithelial inclusions (OEI) (n=30), serous cystadenoma (n=14), serous borderline tumor (n=12), serous carcinoma (n=20), mucinous cystadenoma (n=10), mucinous borderline tumor (n=10), mucinous carcinomas (n=10), endometrioid carcinomas (n=12), poorly/undifferentiated carcinomas (n=5), and fallopian tube (n=12). Results: Strong and diffuse staining of prohibitin was detected in luteinized ovarian stromal cells, follicular cells, fallopian tube, and OEI with serous differentiation. A significantly higher prohibitin expression in luteinized stromal cells than in non-luteinized stromal cells was observed (P<.01). Within the ovarian epithelium, the level of prohibitin expression was basically negative in ovarian surface epithelia, but highly expressed in OEI. However, compared to the level of prohibitin expression in OEI, it showed a trend of gradual loss from benign ovarian tumors, to borderline tumors and to carcinomas (P<.0001). Compared to the serous tumors, epithelial tumors with mucinous differentiation showed a significant lower level of prohibitin (P<.0001). An inverse correlation was noted between prohibitin expression and cancer grade. It is interesting to note that a high prohibitin expression level was seen in the fallopian tube, which is similar to OEI. Conclusions: These data further suggest that prohibitin plays a tumor suppressing role, which is probably associated with LH mediated protection role against ovarian epithelial carcinoma. In addition to the tumor suppressive role of prohibitin, it also plays a role in cellular differentiation, which may be helpful to differentiate ovarian mucinous tumors from the tumors with serous differentiation in clinical settings. More importantly, our findings are supportive that the ovarian epithelial cancers, particularly the serous cancers including those precursors with serous differentiation are likely to be derived from fallopian tube instead of ovarian surface epithelia.     

A multistep model for ovarian tumorigenesis: the value of mutation analysis in the KRAS and BRAF genes

Epithelial ovarian tumours represent a complex group of histological subtypes and there has long been controversy over the question of a precursor lesion for these neoplasms. The application of mutation analysis of the KRAS and BRAF genes (members of the RAS-RAF-MEK-ERK-MAP kinase pathway) is consistent with the model for progression of mucinous carcinomas and a subset of serous carcinomas (the so-called low-grade serous carcinomas) through benign and borderline lesions. The relatively high incidence of BRAF and KRAS mutations in serous borderline tumours and low-grade serous carcinomas, and their extremely low incidence/absence in high-grade serous carcinomas, provide strong evidence that high-grade carcinomas do not arise through this intermediate step.     

Molekularpathologie der epithelialen Ovarialneoplasien

Despite the fact that ovarian carcinomas are phenotypically heterogeneous, they can be divided into two main groups with common pathogenetic mechanisms. Based on clinical, pathological and molecular parameters, a relatively large group of tumors can be distinguished with stepwise development from benign precursors and borderline tumors to invasive carcinomas (type I). Depending on the morphological phenotype, characteristic genetic changes can be observed, such as mutations in KRAS and BRAF in serous borderline tumors and low-grade serous carcinomas. Mutations in KRAS are also frequently detected in mucinous borderline tumors and mucinous carcinomas. The group of endometrioid tumors is characterized by mutations in components of the Wnt-signal transduction pathway and PTEN or microsatellite instability. The second large group of tumors (type II) includes tumors with "de novo" development of highly malignant carcinomas such as the conventional (moderately to poorly differentiated) high-grade serous carcinomas, undifferentiated carcinomas and malignant mixed mesodermal tumors. These tumors are associated with frequent mutations in p53 and complex chromosomal alterations. In the future, the combined analysis of morphological parameters, genetic changes, gene-expression profiling and protein data will reveal possible diagnostic and therapeutic targets for ovarian carcinomas.     

Genomic imbalances in ovarian borderline serous and mucinous tumors

We analyzed 25 ovarian borderline tumors (13 serous and 12 mucinous tumors) by comparative genomic hybridization (CGH). Genomic imbalance was detected in 85% of serous tumors and 75% of mucinous tumors. Different patterns of genomic alterations were identified in serous and mucinous tumors. Gain of the X chromosome was common in both serous (30%) and mucinous (42%) tumors. However, gain of chromosome 8 was detected exclusively in 38% of serous and mixed sero-mucinous tumors, but not in any pure mucinous tumors. According to the present and previous studies, gain of chromosome 8 is the most common abnormality in borderline serous tumors. Gain of the same chromosome is also common in high grade and advanced stage serous carcinomas, but uncommon in early stage serous carcinomas. In addition gain of chromosome X is common in borderline serous and mucinous tumors, while loss of chromosome X is predominant in invasive carcinomas. These findings do not support the multi-step progression theory from borderline tumor to high-grade, advanced stage carcinoma, but indicate that the borderline ovarian tumor is a distinct entity. Genes in chromosome 8 may be critical for the development and the differentiation of borderline serous tumors.     

Expression of Tn and sialyl-Tn antigens in tumor tissues of the ovary.

The expression of sialyl-Tn and Tn antigens in various benign, borderline, and malignant ovarian tumors was examined immunohistochemically using newly developed antibodies specific for sialyl-Tn and Tn antigens. Sialyl-Tn antigen was detected in only one benign tumor, a mucinous adenoma that showed faint cytoplasmic staining in a few cells. However, sialyl-Tn was present in 5 of 12 serous borderline tumors, 10 of 19 mucinous borderline tumors, 10 of 13 serous adenocarcinomas, 15 of 16 mucinous adenocarcinomas, 14 of 15 endometrioid adenocarcinomas, and 7 of 7 clear cell carcinomas of the ovary. The antigen expression was observed throughout the cytoplasm of cancer cells and in the apical cytoplasm and luminal contents of some glands. The incidence and intensity of staining for sialyl-Tn antigen were higher in malignant tumors than in borderline tumors, but these results did not correlate with the histologic classification or differentiation. Coexpression of sialyl-Tn antigen and Tn antigen was observed in two serous adenocarcinomas, six mucinous borderline tumors, five mucinous adenocarcinomas, eight endometrioid, and seven clear cell carcinomas. In no case was Tn antigen expressed without concomitant sialyl-Tn antigen expression. Accumulation of sialyl-Tn antigen seems to be an early event of carcinogenesis of the ovary.     

Expression of Rsf-1, a chromatin-remodeling gene, in ovarian and breast carcinoma

Rsf-1 protein is a member of a chromatin-remodeling complex that plays an important role in regulating gene expression and cell proliferation. Our previous study showed that Rsf-1 was an amplified gene that participated in the development of ovarian serous carcinoma. To further elucidate the role of Rsf-1 in ovarian cancer, we studied Rsf-1 immunoreactivity in 294 ovarian tumors of various histologic types. Because the Rsf-1 amplicon overlaps an amplified region reported in breast cancer, we included 782 neoplastic and normal breast tissues for comparison. Immunohistochemistry was performed on tissue microarrays using a 4-tiered scoring system. Overexpression of Rsf-1 was defined as a nuclear immunointensity of 3+ to 4+ because of a strong correlation between 3+ and 4+ immunointensity and Rsf-1 gene amplification, based on our previous fluorescence in situ hybridization analysis. Rsf-1 overexpression was observed in 25% of high-grade ovarian serous carcinomas and in only rare cases (<7%) of low-grade ovarian serous, ovarian endometrioid, and invasive breast carcinomas but not in any ovarian serous borderline tumors, ovarian clear cell carcinomas, ovarian mucinous carcinomas, intraductal carcinomas of the breast, and normal ovaries and breast tissues. Thus, overexpression of Rsf-1 was significantly associated with high-grade ovarian serous carcinoma (P < .05), as compared with other types of ovarian tumors and breast carcinomas. Our results provide evidence that Rsf-1 expression is primarily confined to high-grade serous carcinoma, the most aggressive ovarian cancer. Because Rsf-1 overexpression occurs in only a small number of breast carcinomas, it is unlikely that Rsf-1 is a critical gene in the development of breast carcinoma.     

High-grade ovarian serous carcinoma exhibits significantly higher p16 expression than low-grade serous carcinoma and serous borderline tumour

AIMS: A dualistic pathway of ovarian serous carcinogenesis is now well established whereby high-grade serous carcinoma and low-grade serous carcinoma represent two distinct tumour types with a different underlying pathogenesis. The aim of this study was to compare expression of p16 INK4A (p16) in these two tumour types. We also included cases of serous borderline tumour, since these are considered to represent a precursor lesion of low-grade serous carcinoma. METHODS AND RESULTS: Cases of serous borderline tumour (n = 18), low-grade ovarian serous carcinoma (n = 22) and high-grade ovarian serous carcinoma (n = 24) were stained with a monoclonal antibody against p16. Cases were scored both with respect to intensity of immunoreactivity (weak, 1+; moderate, 2+; or strong, 3+) and distribution (0, negative or occasional positive cells; 1+, < 10% cells positive; 2+, 10-25% cells positive; 3+, 26-50% cells positive; 4+, 51-75% cells positive; or 5+, 76-100% cells positive). An immunohistochemical composite score was also calculated (0-15) by multiplying the intensity and distribution scores. There was a statistically significant difference in p16 immunoreactivity with respect to intensity, distribution and composite score between high-grade serous carcinoma and each of the other two groups, with the high-grade neoplasms exhibiting stronger and more diffuse positivity. Most high-grade serous carcinomas exhibited positivity of close to 100% of tumour cells. There was no significant difference in p16 expression between the borderline tumours and low-grade serous carcinomas. CONCLUSIONS: The increased expression of p16 in high-grade serous carcinoma compared with low-grade serous carcinoma and serous borderline tumour is in keeping with a different underlying pathogenesis. p16 may be implicated in the development of high-grade serous neoplasia within the ovary and elsewhere within the female genital tract.     

Ovarian carcinoma: current diagnostic principles

Ovarian cancer is the most common cause of death from a gynecologic cancer. The most common types of ovarian cancer are carcinomas of surface epithelial-stromal origin. Ovarian carcinomas are a heterogeneous group of neoplasms. Based on proposed different pathways of tumorigenesis, these tumors are divided into two broad subgroups (type I and II) with different biologic behaviour, prognosis and response to therapy. Type I tumors include low-grade serous adenocarcinoma, low-grade endometrioid adenocarcinoma, mucinous adenocarcinoma, malignant Brenner tumor and some clear cell carcinomas. These tumors are low-grade neoplasms evolving from a defined precursor lesion. Type II tumors are high-grade neoplasms including undifferentiated carcinoma, high-grade serous adenocarcinoma, high-grade endometrioid adenocarcinoma, malignant mixed Müllerian tumor and probably some clear cell carcinomas. At present, the histological type of ovarian carcinoma has only limited impact on the management of these tumors. However, with progress towards the type-specific treatment of ovarian carcinoma, accurate histopathological diagnosis of ovarian carcinoma becomes increasingly important. In this review we summarize recent advances in the histopathological diagnosis of ovarian carcinoma. Moreover, we mention genetic changes in different types of ovarian carcinoma.     

Diverse tumorigenic pathways in ovarian serous carcinoma

This study was undertaken to analyze genetic alterations in 108 sporadic serous ovarian neoplasms to elucidate ovarian serous carcinogenesis. Our results demonstrate that K-ras mutations occur in approximately 50% of serous borderline tumors (SBTs), non-invasive micropapillary serous carcinomas (MPSCs), and invasive micropapillary serous carcinomas, which represent a morphological continuum of tumor progression. Moreover, progressive increase in the degree of allelic imbalance of chromosomes 1p, 5q, 8p, 18q, 22q, and Xp was observed comparing serous borderline tumors to noninvasive and invasive micropapillary serous carcinomas. In contrast, high-grade (conventional serous carcinoma) tumors contained wild-type K-ras in all 23 cases studied and a high frequency of allelic imbalance even in small (early) primary tumors similar to that found in advanced stage tumors. Based on these findings, we propose a dualistic model for ovarian serous carcinogenesis. One pathway involves a stepwise progression from SBT to noninvasive and then invasive MPSC. The other pathway is characterized by rapid progression from the ovarian surface epithelium or inclusion cysts to a conventional (high-grade) serous carcinoma.     

Molecular pathogenesis and extraovarian origin of epithelial ovarian cancer--shifting the paradigm

Recent morphologic, immunohistochemical, and molecular genetic studies have led to the development of a new paradigm for the pathogenesis and origin of epithelial ovarian cancer based on a dualistic model of carcinogenesis that divides epithelial ovarian cancer into 2 broad categories designated types I and II. Type I tumors comprise low-grade serous, low-grade endometrioid, clear cell and mucinous carcinomas, and Brenner tumors. They are generally indolent, present in stage I (tumor confined to the ovary), and are characterized by specific mutations, including KRAS, BRAF, ERBB2, CTNNB1, PTEN, PIK3CA, ARID1A, and PPP2R1A, which target specific cell signaling pathways. Type I tumors rarely harbor TP53 mutations and are relatively stable genetically. Type II tumors comprise high-grade serous, high-grade endometrioid, malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated carcinomas. They are aggressive, present in advanced stage, and have a very high frequency of TP53 mutations but rarely harbor the mutations detected in type I tumors. In addition, type II tumors have molecular alterations that perturb expression of BRCA either by mutation of the gene or by promoter methylation. A hallmark of these tumors is that they are genetically highly unstable. Recent studies strongly suggest that fallopian tube epithelium (benign or malignant) that implants on the ovary is the source of low-grade and high-grade serous carcinoma rather than the ovarian surface epithelium as previously believed. Similarly, it is widely accepted that endometriosis is the precursor of endometrioid and clear cell carcinomas and, as endometriosis, is thought to develop from retrograde menstruation; these tumors can also be regarded as involving the ovary secondarily. The origin of mucinous and transitional cell (Brenner) tumors is still not well established, although recent data suggest a possible origin from transitional epithelial nests located in paraovarian locations at the tuboperitoneal junction. Thus, it now appears that type I and type II ovarian tumors develop independently along different molecular pathways and that both types develop outside the ovary and involve it secondarily. If this concept is confirmed, it leads to the conclusion that the only true primary ovarian neoplasms are gonadal stromal and germ cell tumors analogous to testicular tumors. This new paradigm of ovarian carcinogenesis has important clinical implications. By shifting the early events of ovarian carcinogenesis to the fallopian tube and endometrium instead of the ovary, prevention approaches, for example, salpingectomy with ovarian conservation, may play an important role in reducing the burden of ovarian cancer while preserving hormonal function and fertility.     

BRAF Mutation Is Rare in Advanced-Stage Low-Grade Ovarian Serous Carcinomas

Low-grade ovarian serous carcinomas are believed to arise via an adenoma-serous borderline tumor-serous carcinoma sequence. In this study, we found that advanced-stage, low-grade ovarian serous carcinomas both with and without adjacent serous borderline tumor shared similar regions of loss of heterozygosity. We then analyzed 91 ovarian tumor samples for mutations in TP53, BRAF, and KRAS. TP53 mutations were not detected in any serous borderline tumors (n = 30) or low-grade serous carcinomas (n = 43) but were found in 73% of high-grade serous carcinomas (n = 18). BRAF (n = 9) or KRAS (n = 5) mutation was detected in 47% of serous borderline tumors, but among the low-grade serous carcinomas (39 stage III, 2 stage II, and 2 stage I), only one (2%) had a BRAF mutation and eight (19%) had a KRAS mutation. The low frequency of BRAF mutations in advanced-stage, low-grade serous carcinomas, which contrasts with previous findings, suggests that aggressive, low-grade serous carcinomas are more likely derived from serous borderline tumors without BRAF mutation. In addition, advanced-stage, low-grade carcinoma patients with BRAF or KRAS mutation have a better apparent clinical outcome. However, further investigation is needed.Serous carcinoma is the most common histological subtype of epithelial ovarian cancer. Recent evidence strongly suggests that a two-tier system stratifying serous carcinoma into low-grade and high-grade categories is biologically and clinically relevant.^1–12 Low-grade serous carcinomas are believed to arise via an adenoma–serous borderline tumor–carcinoma sequence, whereas high-grade serous carcinomas develop from an unknown precursor.^6,7 While previous reports indicate that low-grade serous carcinomas may develop from either recurrence of a serous borderline tumor or de novo, the mechanism associated with the former type of development is not fully understood.^13–15 Almost all serous borderline tumors that recur are associated with noninvasive or invasive peritoneal implants (stages II–IV) at initial diagnosis of the serous borderline tumor.^13–17According to the World Health Organization, the pattern of serous borderline tumors may be classified as either typical or micropapillary.^15,18–21 The micropapillary pattern was initially described in 1996; accounts for 8% to 18% of serous borderline tumors; and is associated with a greater frequency of bilaterality, a greater association with peritoneal implants (particularly invasive implants), and a higher risk of relapse than the typical pattern of serous borderline tumor.^15,18–21 For all serous borderline tumors, regardless of the pattern, the risk of relapsing as low-grade ovarian serous carcinoma increases over time.²²Mutation analysis could provide insight into how low-grade serous carcinoma develops. The initial report on BRAF and KRAS mutations in low-grade serous carcinomas, which were believed to be derived from serous borderline tumors with micropapillary pattern, indicated a rate of BRAF or KRAS mutation of 68%.²³ Similarly, in serous borderline tumors, a rate of BRAF or KRAS mutation of 61% was reported.²³ However, in invasive high-grade serous carcinomas, BRAF and KRAS mutations were not found.^23–25 Conversely, TP53 mutations are quite common in high-grade serous carcinomas but exceedingly rare in serous borderline tumors and low-grade serous carcinomas.²⁶ However, the correlation of BRAF/KRAS with patient outcome in low-grade ovarian serous carcinomas has not been explored. In this study, we investigated the BRAF and KRAS mutation status of advanced-stage low-grade serous carcinomas with and without a background of serous borderline tumor at initial diagnosis.     

p73基因在卵巢上皮性肿瘤中的表达及甲基化研究

目的 探讨卵巢上皮性肿瘤中p73蛋白的表达和基因启动子的甲基化情况,并观察其与临床病理学特征的关系.方法 制备包括68例卵巢癌、37例卵巢交界性肿瘤和21例卵巢良性肿瘤的组织芯片,用免疫组织化学EnVision法检测上述组织中p73蛋白表达情况,用亚硫酸氧盐修饰后测序法检测13例新鲜卵巢癌组织及5例新鲜卵巢交界性肿瘤组织的p73基因启动子甲基化情况.结果 92.6％ (63/68)的卵巢癌表达p73,p73蛋白总体表达率均值为32％(p73表达率指p73阳性细胞数所占的百分比),其中浆液性癌( 26/26)的表达率均值为40％,高于其他组织类型的癌(P=0.006).按照卵巢癌发病模式区分,Ⅱ型卵巢癌p73表达率均值(40％)高于Ⅰ型卵巢癌(24％),P=0.010.卵巢癌中p73的表达与临床分期及组织学分级无相关性(均P＞0.05).卵巢交界性肿瘤组(30/37)和良性肿瘤组(12/21)p73的总体表达率均值分别为16％和15％,该两组肿瘤中浆液性肿瘤表达率均值均高于黏液性肿瘤(P-0.003,P=0.026).卵巢癌组的p73阳性表达率均值明显高于交界性肿瘤组和良性肿瘤组(均P ＜0.05),交界性肿瘤组与良性肿瘤组比较差异无统计学意义(P＞0.05).浆液性肿瘤( 49/53)中,卵巢癌组(26/26) p73阳性表达率均值明显高于交界性肿瘤组(12/14)和良性肿瘤组(11/13;P =0.024和P=0.002),而卵巢交界性肿瘤组和良性肿瘤组比较差异无统计学意义(P=0.428).黏液性肿瘤(15/27)中,卵巢癌组(6/7)p73阳性表达率均值高于良性肿瘤组( 1/8;p=0.032),而卵巢癌组与卵巢交界性肿瘤组(8/12)、交界性肿瘤组与良性肿瘤组比较,差异均无统计学意义(P=0.234和P=0.201).p73启动子的甲基化结果显示,13例卵巢癌有8例发生甲基化,但每例样本甲基化频率有所不同,总体甲基化频率均值为8.0％.5例交界性肿瘤有2例发生甲基化,总体甲基化频率均值为9.0％,两组比较差异无统计学意义(P＞0.05).卵巢癌组p73甲基化额率与组织类型、发病模式、组织学分级及临床分期均无相关性(均P＞0.05).结论 卵巢上皮性肿瘤多数表达p73,卵巢癌p73的表达率均值明显高于交界性肿瘤和良性肿瘤,浆液性肿瘤高于其他组织类型;p73蛋白表达率与p73基因甲基化程度不存在简单线性相关关系.     

Overexpression of p21WAF1/CIP1 and MDM2 characterizes serous borderline ovarian tumors

Ovarian epithelial tumors are classically divided into benign, malignant, and borderline or of low malignant potential. It is controversial whether this last group of tumors should be considered benign or malignant. Expression of cell cycle markers has recently been linked to tumor behavior and response to treatment. It has been shown that one of the pathways through which the p53 gene controls the cell cycle is by transactivating p21WAF1/CIP1, a cyclin-dependent kinase (cdk) inhibitor. By inhibiting cdks, p21WAF1/CIP1 blocks the G-1 to S-phase transition in the cell cycle. p53 can be regulated by MDM2 (murine double minute-2) through direct inactivation or promotion of its cytoplasmic degradation. In an attempt to investigate the cell cycle checkpoint mechanisms of these tumors, we studied the expression of p53, Ki-67, MDM2, and p21WAF1/CIP1 by immunohistochemistry. We analyzed the expression of these proteins in 19 cystadenomas (8 serous and 11 mucinous), 40 borderline tumors (31 serous and 9 mucinous), and 18 serous carcinomas of the ovary. p21WAF1/CIP1 was expressed in 7 of 19 (37%) benign cystadenomas, 32 of 40 (80%) borderline tumors (93.5% of serous and 33% of mucinous), and in 9 of 18 (50%) serous carcinomas. Ki-67 was only weakly expressed in 8 of 19 (42%) benign cystadenomas, all borderline tumors showed Ki-67 staining in less than 50% of the cells, and 55% of serous carcinomas stained in more than 50% of tumor cells. p53 was absent in all but 1 of the cystadenomas, was expressed in 9 of 40 (22.5%) borderline tumors (25.8% of serous and 11% of mucinous), and in 10 of 18 (55%) carcinomas. All 11 implants of serous borderline tumors expressed p21WAF1/CIP1. Most serous borderline tumors expressed higher levels of MDM2 compared with the benign cystadenomas and carcinomas. Four of the serous borderline implants (40%) expressed MDM2. Coexpression of p21WAF1/CIP1 and MDM2 characterizes serous borderline tumors of the ovary and their implants, which suggests that these cell cycle control proteins are important in these tumors and may be related to tumor progression. Low expression of p53 protein in serous borderline tumors might be in part mediated by MDM2. This suggests that the p53 pathway is intact in most of these tumors, in contrast with carcinomas, in which high expression of p53 has been related to mutations of this gene.     

叶酸受体α在卵巢上皮性肿瘤中的表达

目的 探讨卵巢上皮性肿瘤中叶酸受体(FR)α的表达及其临床病理学意义.方法 制备包括86例卵巢癌及29例卵巢交界性肿瘤的组织芯片,采用免疫组织化学EnVision法检测上述肿瘤组织中FRα的表达情况,同时采用即时PCR检测40例新鲜冷冻卵巢癌组织以及14例卵巢交界性肿瘤组织中FRα mRNA的表达情况.分析卵巢上皮性肿瘤中FRα表达水平与肿瘤的组织类型、不同发病模式以及临床分期的关系.结果 免疫组织化学染色结果显示,86例卵巢癌中有40例(46.5%)对FRα呈明确阳性反应,其中浆液性癌阳性表达率最高,为62.7%(32/51),高于其他组织类型的癌(P=0.000).按照卵巢癌发病模式区分,Ⅱ型卵巢癌FRα的表达明显高于Ⅰ型卵巢癌,差异具有统计学意义(P=0.001).卵巢癌组FRα表达阳性率高于交界性肿瘤(46.5%∶27.6%),但差异无统计学意义(P=0.074).卵巢癌组FRα的表达与临床分期无相关性(P=0.498).相似的结果也见于采用即时PCR检测FRα mRNA的表达情况:卵巢癌组FRα mRNA表达值高于交界性肿瘤组(P=0.000),在交界性肿瘤中,浆液型mRNA表达值高于黏液型,差异具有统计学意义(P=0.007).结论 卵巢上皮性肿瘤中FRα呈高表达,特别是在恶性肿瘤和浆液性肿瘤中.     

My approach to and thoughts on the typing of ovarian carcinomas

Ovarian carcinomas of epithelial type comprise a heterogeneous group of neoplasms, each with a different underlying pathogenesis and natural behaviour. Accurate classification of ovarian carcinomas is important since each type may be associated with a different behaviour, natural history and outcome. Precise classification is also critical to determine whether alternative therapeutic strategies are appropriate for different tumour types. Previous studies have shown significant interobserver variation in the typing of ovarian carcinomas. There are several areas where there are particular difficulties; these include the distinction between high-grade serous and endometrioid adenocarcinomas and the distinction between a true clear cell carcinoma and clear cell areas within other adenocarcinomas. This review details my approach to the typing of ovarian carcinomas. Morphological assessment, which remains the mainstay in diagnosis, can be supplemented by immunohistochemistry which, for example, is useful in the distinction between serous carcinomas (WT1 positive) and other carcinomas (generally WT1 negative). In recent years, there has been emerging new information regarding the major underlying molecular events in several types of ovarian carcinoma. This has resulted in the acceptance that there are two distinct types of ovarian serous carcinoma. These are termed low-grade and high-grade serous carcinoma, but represent two distinct tumour types rather than low-grade and high-grade variants of the same neoplasm. The integration of clinical, morphological and molecular data has resulted in a more precise classification of ovarian carcinomas and has resulted in the proposal for a broad dualistic pathway of ovarian epithelial carcinogenesis with, in general, low-grade type 1 tumours evolving from benign and borderline neoplasms through a well-defined adenoma-carcinoma sequence, and high-grade type 2 neoplasms arising from an, as yet, undefined precursor lesion.     

Neuroendocrine cells in cystic mucinous tumours of the ovary

This histogenesis of cystic mucinous ovarian tumours is still controversial. It has been proposed that these neoplasms may arise from metaplastic ovarian surface epithelium. Others have suggested that these tumours represent monophyletic (intestinal) types of teratoma. Against this background we have studied the presence of different types of neuroendocrine cells in a series of cystic mucinous ovarian tumours. Argyrophil neuroendocrine cells were found almost exclusively in tumours which were histologically classified as borderline or low-grade mucinous carcinomas, whereas these cells were very rare in mucinous cystadenomas and in grade III and IV carcinomas. Several gut peptide hormones could be demonstrated in these cells, but only in borderline tumours and low-grade mucinous carcinomas. Mucin histochemistry did not reveal characteristic patterns in these neoplasms. The results confirm that with regard to the presence of endocrine cells the epithelium of borderline mucinous cystadenomas and mucinous cystadenocarcinomas bears strong resemblance to intestinal epithelium. These findings do not rule out the possibility that these tumours arise by metaplasia from ovarian germinal epithelium but are equally compatible with a teratomatous origin. The epithelium of most benign mucinous cystadenomas resembles that of ovarian inclusion cysts.