卵巢上皮性肿瘤中FKBP38 蛋白的表达研究

目的:探讨卵巢上皮性肿瘤中FK506结合蛋白38(FK506-binding protein 38,FKBP38)蛋白的表达及潜在的临床意义。方法:采用免疫组化的方法检测20例正常输卵管组织,30例卵巢上皮性良性肿瘤,27例卵巢交界性肿瘤组织,130例卵巢上皮性癌(epithelial ovarian carcinoma,EOC)组织中FKBP38蛋白的表达,并分析其表达水平与临床病理参数的关系。结果:FKBP38蛋白在卵巢上皮性癌中的表达明显低于正常输卵管组织、卵巢上皮性良性和交界性肿瘤组织,差异有统计学意义(P0.05)。FKBP38蛋白表达在根据国际妇产科联盟(International Federation of Gynecology and Obstetrics,FIGO)标准定义的不同分期的卵巢上皮性癌组织中具有统计学差异(P0.05)。FKBP38蛋白在卵巢高级别浆液性癌的表达比低级别浆液性癌中的表达显著性降低(P0.05)。但把卵巢上皮性癌按照不同年龄及不同组织学分型分层后,FKBP38蛋白表达差异无统计学意义(P0.05)。结论:FKBP38蛋白表达的下调可能与卵巢上皮性癌的发生和分化密切相关,提示FKBP38蛋白作为卵巢恶性肿瘤诊断和治疗的潜在性生物靶点需进一步探索和研究。     

Eotaxin-1在浆液性卵巢癌组织中的表达及临床意义研究

目的:研究嗜酸性粒细胞趋化因子1(Eotaxin-1)在浆液性卵巢癌组织中的表达及临床病理意义。方法:收集2013年4月至2014年5月于我院妇产科手术切除的60例浆液性卵巢癌及对应癌旁组织,采用免疫组织化学染色检测Eotaxin-1表达,分析Eotaxin-1蛋白与肿瘤临床病理资料之间的相关性。结果:浆液性卵巢癌组织中Eotaxin-1蛋白表达水平较对应癌旁组织显著升高(P0.05),浆液性卵巢癌组织中高表达Eotaxin-1蛋白与恶性组织病理分级、淋巴结转移及高TNM分期呈显著正相关(P0.05)。结论:Eotaxin-1蛋白在浆液性卵巢癌组织中表达上调,并与肿瘤恶性临床病理特征有关;Eotaxin-1可能成为浆液性卵巢癌早期诊断的重要标志物和生物靶向治疗的有效靶点之一,具有广阔的临床应用前景。     

ER/PR阳性和阴性乳腺癌的定量蛋白质组学和生物信息学比较研究

目的:建立雌/孕激素受体(ER/PR)阴性和阳性乳腺癌的蛋白质表达谱,寻找ER/PR阴性和阳性乳腺癌中差异表达蛋白,为乳腺癌患者提供新的预后预测指标和治疗新靶点。方法:应用蛋白质组学i TRAQ技术建立ER/PR阳性和阴性乳腺癌的蛋白质差异表达谱,鉴定两组乳腺癌的差异表达蛋白,对部分差异表达蛋白进行生物信息学分析,包括蛋白功能注释和分类GO分析和KEGG通路分析。结果:应用i TRAQ蛋白质组学技术对乳腺癌组织进行了蛋白组学分析,鉴定出ER/PR阳性和阴性组间有差异表达的蛋白4999种,以ER/PR阳性:ER/PR阴性≥3为上调标准,确定ER/PR阳性组上调蛋白101种。以ER/PR阳性:ER/PR阴性≤0.5为下调标准,ER/PR阳性组下调蛋白122种。GO分析结果显示ER/PR受体阴性和阳性乳腺癌的差异表达蛋白的分子功能、生物过程、细胞定位较为复杂,并且在上调蛋白和下调蛋白上存在分布差异。KEGG通路分析发现部分差异表达蛋白涉及201条信号通路。结论:ER/PR阳性和阴性乳腺癌间存在差异表达蛋白,这些蛋白涉及复杂的分子功能、生物过程和信号通路。     

浆液性卵巢癌铁死亡关键基因的筛选及[]生物信息学分析

利用生物信息学方法筛选浆液性卵巢癌相关铁死亡关键基因,并预测其生物学功能。从GEO数据库中获得有关浆液性卵巢癌的数据集GSE54388和GSE12470,采用R语言中的“Limma”包分析挑选浆液性卵巢癌上皮组织与正常卵巢上皮组织中差异表达基因,绘制火山图、热图。利用Venn软件在线工具绘制GSE54388,GSE12470,FerrDb三个数据集韦恩图。对相关基因进行功能富集分析、蛋白互作分析、生存分析,对关键基因绘制ROC曲线进行诊断分析。采用GEPIA2 数据库对筛选基因进行验证,并进行免疫浸润分析。结果发现:从GSE54388中筛选出2458个差异基因,其中上调1309个,下调1149个。从GSE12470中筛选出3534个差异基因,其中上调1 837个,下调1 697个。与铁死亡基因数据集取交集,共得到16个差异基因,蛋白互作网络筛选出7个基因构建的关键模块,绘制生存曲线发现浆液性卵巢癌患者中5个基因与患者总生存率不良相关,其中NRAS,PSAT1,CDKN2A,GDF15这4个基因高表达,CAV1低表达。ROC曲线显示这5个基因中CAV1,NRAS,PSAT1的AUC诊断曲线面积大于0.95,有较高的诊断价值。GEPIA2 数据库验证发现5个基因的表达情况与预测相符,仅NRAS基因表达在浆液性卵巢癌患者Ⅱ期、Ⅲ期、Ⅳ期有显著差异(P<0.05)。免疫浸润分析发现CDKN2A表达与aDC细胞浸润水平呈正相关(P<0.05,spearman相关系数0.353);CAV1表达与Mast细胞浸润正向关(P<0.05,spearman相关系数0.327);NRAS与T helper细胞浸呈正向关(P<0.05,spearman相关系数0.362)。通过生物信息学方法筛选出与浆液性卵巢癌铁死亡相关的5个基因CAV1,NRAS,PSAT1,CDKN2A,GDF15,可能在浆液性卵巢癌的发生发展中起重要作用,有望成为该病诊断、治疗和预后的潜在分子生物标志物。     

联合检测血清糖类抗原标志物在女性绝经前后卵巢浆液性癌诊断中的价值

目的:探讨联合检测血清糖类抗原标志物在女性绝经前后卵巢浆液性癌诊断中的价值。方法:采用回顾性研究方法,选择2016年8月到至2018年2月在我院肿瘤科进行检测的绝经前后卵巢浆液性癌患者60例(癌变组)与绝经前后健康体检者60例(健康对照组),检测其血清癌胚抗原(carcino-embryonic antigen,CEA)、人附睾蛋白4(human epididymis protein 4,HE4)和糖链抗原125(carbohydrate antigen 125,CA125)的水平,并分析其与患者的临床病理特征与随访预后的相关性。结果:癌变组血清CEA、HE4、CA125水平及阳性表达率都均显著高于健康对照组(P0.05)。在癌变组60例患者中,随着病理分期增加、分化程度的减少、淋巴结转移与死亡情况的发生,血清CEA、HE4、CA125的阳性表达率显著升高,对比差异有统计学意义(P0.05)。同时在120例人群中,联合诊断为卵巢浆液性癌者54例,联合诊断的敏感性与特异性分别为90.0%和100.0%。结论:绝经前后女性卵巢浆液性癌患者血清糖类抗原标志物-CEA、HE4、CA12水平均呈现高表达,可能作为绝经前后女性卵巢浆液性癌诊断与预后预测的参考指标。     

E-cadherin,β-catenin,N-cadherin在卵巢浆液性癌中的表达及意义

目的研究浆液性卵巢癌中E-钙粘蛋白(E-cadherin,E-cad),β-连环蛋白(β-catenin,β-cat),N-钙粘蛋白(N-cadherin,N-cad)的表达,探讨其相关性及临床意义。方法采用免疫组织化学法检测60例卵巢浆液性癌中E-cadherin,β-catenin and N-cadherin的表达。结果 E-cadherin,β-catenin在卵巢浆液性癌、卵巢浆液性良性肿瘤和卵巢交界性肿瘤及正常卵巢组织间差异有统计学意义(P0.05),而在卵巢良性肿瘤和卵巢交界性肿瘤间,差异不大,无统计学意义(P0.05)。N-cadherin在卵巢浆液性癌与卵巢交界性肿瘤,卵巢浆液性良性瘤及正常卵巢组织间差异有统计学意义(P0.05),而在正常卵巢组织、卵巢良性肿瘤和卵巢交界性肿瘤间,无差异,无统计学意义。结论 E-钙粘蛋白(E-cadherin),β-连环蛋白(β-catenin),N-钙粘蛋白(N-cadherin)在浆液性卵巢癌中均存在异常表达。提示三种因子可能造成肿瘤的发生、发展、侵袭及转移。三者同时检测,可能为早期诊断上皮性卵巢癌及针对上皮性卵巢癌的靶向治疗提供分子依据及新的思路。     

EGFR和KRAS在上皮性卵巢癌组织中的表达及临床意义

目的:探讨表皮生长因子受体(EGFR)和鼠Kirsten肉瘤病毒致癌基因(KRAS)蛋白在上皮性卵巢癌组织中的表达水平及临床意义。方法:利用免疫组化SP法对上皮性卵巢癌组织(病例组,n=57)、卵巢良性肿瘤组织(良性组,n=50)以及正常卵巢组织(对照组,n=50)中的EGFR、KRAS蛋白水平进行检测,并分析其在上皮性卵巢癌发生发展中的作用。结果:病例组的EGFR、KRAS蛋白阳性率高于良性组和对照组(P0.05),良性组和对照组的EGFR、KRAS蛋白阳性率差异无统计学意义(P0.05)。浆液性腺癌组EGFR、KRAS蛋白的阳性表达率高于非浆液性腺癌组,Ⅲ~Ⅳ期的上皮性卵巢癌组织中EGFR、KRAS蛋白阳性表达率高于Ⅰ~Ⅱ期,中、低分化组中EGFR、KRAS蛋白阳性表达率高于高分化组,差异均具有统计学意义(P0.05)。上皮性卵巢癌组织中EGFR与KRAS的蛋白的阳性表达率呈正相关关系(r=0.469,P0.05)。结论:EGFR及KRAS蛋白在上皮性卵巢癌组织中的表达水平明显升高,可能参与了上皮性卵巢癌的发生发展过程,且两者之间呈正相关关系,联合检测可作为早期诊断上皮性卵巢癌的重要指标。     

膜联蛋白A4表达与卵巢浆液性囊腺癌化疗耐药性相关

目的:了解膜联蛋白A4(Annexin A4)在不同卵巢组织中的表达及其与卵巢浆液性囊腺癌患者临床病理因素之间的关系,明确Annexin A4表达与卵巢浆液性囊腺癌患者化疗敏感性是否有关。方法:通过免疫组化SP法检测58例卵巢浆液性囊腺癌组织和30例良性卵巢肿瘤中Annexin A4表达水平,对卵巢浆液性囊腺癌病人进行随访,了解其化疗敏感性,进行统计分析。结果:Annexin A4在卵巢浆液性囊腺癌组织中(74.1%)表达明显高于良性卵巢肿瘤(26.7%)(P0.05),且其表达在有无淋巴结转移及有无绝经的卵巢浆液性囊腺癌患者中无显著性差异(P0.05),而与患者组织分化程度、手术病理分期有关(P0.05)。Annexin A4蛋白在化疗耐药组(92.0%)的表达明显高于化疗敏感组(60.6%)(P0.05)。结论:Annexin A4在卵巢浆液性乳头状囊腺癌的发生发展中可能起重要作用,且与患者化疗耐药性有关,有望成为预测化疗敏感性的生物学指标。     

多组学分析揭示Grb2介导α-硫辛酸抑制肝癌细胞增殖研究

目的:为更深入了解α-硫辛酸如何影响复杂信号通路间的相互作用抑制细胞增殖。方法:我们凭借RNA-Seq与同位素相对标记与绝对定量技术,对α-LA处理24 h HepG2细胞在转录和蛋白表达水平的变化差异进行分析,并借助实时定量PCR免疫印迹技术对组学数据进行了鉴定。结果:转录组学提示共有4,446个基因(2,097个基因表达下调,2,349个基因表达上调)的表达在α-LA处理24 h后呈现显著性改变。GO分析提示,编码肿瘤相关细胞膜蛋白的基因是受α-LA影响最为显著的一类mRNA;蛋白质组学进一步提示Grb2可能是受α-LA调控的膜受体信号通路中关键的靶分子。结论:α-LA抑制HCC细胞增殖是通过下调Grb2介导的相关通路而实现。     

miR-450a-5p在浆液性卵巢癌中的表达及临床意义

目的:检测miR-450a-5p在浆液性卵巢癌中的表达情况,并分析miR-450a-5p的表达与浆液性卵巢癌临床病理特征之间的关系,探讨其在浆液性卵巢癌发生、发展中的意义。方法:采用实时荧光定量PCR技术,检测101例浆液性卵巢癌组织及对照50例正常输卵管伞端组织中miR-450a-5p的表达情况,并分析miR-450a-5p表达水平与临床病理特征之间的关系。实验数据采用统计学软件进行分析。结果:miR-450a-5p在浆液性卵巢癌组织中的表达量显著低于正常输卵管组织对照组(P0.01)。miR-450a-5p的表达水平与浆液性卵巢癌临床病理特征之间差异均无统计学意义(P0.05)。结论:miR-450a-5p可能作为抑癌基因,在卵巢癌的发生、发展中发挥重要作用,进一步的研究有望为浆液性卵巢癌的早期诊断及个体化治疗提供新的理论依据。     

N-cadherin在卵巢癌中的表达及其临床病理意义

目的:探讨N-cadherin在人类卵巢癌组织中的表达及其临床-病理意义。方法:采用免疫组织化学染色法检测281例卵巢癌患者肿瘤组织中N-cadherin的表达,并分析其与患者临床病理特征之间的关系。结果:N-cadherin在卵巢癌原发灶中的表达显著低于配对的转移灶(P=0.018);卵巢癌组织中N-cadherin的表达与患者FIGO分期(P=0.034)、组织学类型(P0.001)、肿瘤分级(P=0.004)均显著相关。结论:N-cadherin高表达更多见于进展期(FIGOⅡ-Ⅳ)卵巢癌、高级别浆液性癌及高级别卵巢癌,可能与卵巢癌细胞的侵袭及迁移能力呈正相关,对判断卵巢癌的生物学行为具有重要的参考价值。     

Gene expression signatures differentiate ovarian/peritoneal serous carcinoma from breast carcinoma in effusions

Ovarian/primary peritoneal carcinoma and breast carcinoma are the gynaecological cancers that most frequently involve the serosal cavities. With the objective of improving on the limited diagnostic panel currently available for the differential diagnosis of these two malignancies, as well as to define tumour‐specific biological targets, we compared their global gene expression patterns. Gene expression profiles of 10 serous ovarian/peritoneal and eight ductal breast carcinoma effusions were analysed using the HumanRef‐8 BeadChip from Illumina. Differentially expressed candidate genes were validated using quantitative real‐time PCR and immunohistochemistry. Unsupervised hierarchical clustering using all 54,675 genes in the array separated ovarian from breast carcinoma samples. We identified 288 unique probes that were significantly differentially expressed in the two cancers by greater than 3.5‐fold, of which 81 and 207 were overexpressed in breast and ovarian/peritoneal carcinoma, respectively. SAM analysis identified 1078 differentially expressed probes with false discovery rate less than 0.05. Genes overexpressed in breast carcinoma included TFF1, TFF3, FOXA1, CA12, GATA3, SDC1, PITX1, TH, EHFD1, EFEMP1, TOB1 and KLF2. Genes overexpressed in ovarian/peritoneal carcinoma included SPON1, RBP1, MFGE8, TM4SF12, MMP7, KLK5/6/7, FOLR1/3, PAX8, APOL2 and NRCAM. The differential expression of 14 genes was validated by quantitative real‐time PCR, and differences in 5 gene products were confirmed by immunohistochemistry. Expression profiling distinguishes ovarian/peritoneal carcinoma from breast carcinoma and identifies genes that are differentially expressed in these two tumour types. The molecular signatures unique to these cancers may facilitate their differential diagnosis and may provide a molecular basis for therapeutic target discovery.     

MicroRNA Profiling of BRCA1/2 Mutation-Carrying and Non-Mutation-Carrying High-Grade Serous Carcinomas of Ovary

Background

MicroRNAs (miRNA) are 20∼25 nucleotide non-coding RNAs that inhibit the translation of targeted mRNA, and they have been implicated in the development of human malignancies. High grade serous ovarian carcinomas, the most common and lethal subtype of ovarian cancer, can occur sporadically or in the setting of BRCA1/2 syndromes. Little is known regarding the miRNA expression profiles of high grade serous carcinoma in relation to BRCA1/2 status, and compared to normal tubal epithelium, the putative tissue of origin for high grade serous carcinomas.

Methodology/Principal Findings

Global miRNA expression profiling was performed on a series of 33 high grade serous carcinomas, characterized with respect to BRCA1/2 status (mutation, epigenetic silencing with loss of expression or normal), and with clinical follow-up, together with 2 low grade serous carcinomas, 2 serous borderline tumors, and 3 normal fallopian tube samples, using miRNA microarrays (328 human miRNA). Unsupervised hierarchical clustering based on miRNA expression profiles showed no clear separation between the groups of carcinomas with different BRCA1/2 status. There were relatively few miRNAs that were differentially expressed between the genotypic subgroups. Comparison of 33 high grade serous carcinomas to 3 normal fallopian tube samples identified several dysregulated miRNAs (false discovery rate <5%), including miR-422b and miR-34c. Quantitative RT-PCR analysis performed on selected miRNAs confirmed the pattern of differential expression shown by microarray analysis. Prognostically, lower level miR-422b and miR-34c in high grade serous carcinomas were both associated with decreased disease-specific survival by Kaplan-Meier analysis (p<0.05).

Conclusions/Significance

High grade serous ovarian carcinomas with and without BRCA1/2 abnormalities demonstrate very similar miRNA expression profiles. High grade serous carcinomas as a group exhibit significant miRNA dysregulation in comparison to tubal epithelium and the levels of miR-34c and miR-422b appear to be prognostically important.     

Apoptosis and cell proliferation correlated with tumour grade in peritoneal fluids of patients with serous ovarian cancer

A. Kalogeraki, I. Karvela‐Kalogeraki, P. E. Petraki, I. Zois, D. Tamiolakis and E. N. Stathopoulos
Apoptosis and cell proliferation correlated with tumour grade in peritoneal fluids of patients with serous ovarian cancer Objective: Apoptosis and cell proliferation in peritoneal fluids of patients with ovarian serous adenocarcinoma have not been well described in cytology. To investigate the contribution of cell death to the growth of this tumour we analysed both apoptosis and cell proliferation in peritoneal fluids of patients with ovarian serous adenocarcinoma. Methods: We studied 40 tumours from 40 patients with ovarian serous adenocarcinoma. Twelve tumours were high grade, 13 were moderately differentiated and 15 were poorly differentiated. The detection of DNA fragments in situ using the terminal deoxyribonucleotidy transferase (TDT)‐mediated dUTP‐digoxigenin nick‐end labelling (TUNEL) assay was applied to investigate active cell death (apoptosis), and the MIB‐1 antigen was used to investigate cell proliferation. Results: The TUNEL indices were 0.29 ± 0.05, 0.79 ± 0.10 and 2.1 ± 0.90 in Grade I, Grade II and Grade III ovary carcinomas, respectively. The MIB‐1 antigen labelling indices were 6.5 ± 0.09, 12.9 ± 3 and 25.8 ± 6.2, respectively, in the same order of tumour differentiation. The differences in both TUNEL and MIB‐1 labelling indices were statistically significant between Grade I, Grade II and Grade III carcinomas and there was a positive correlation between the two indices (P < 0.001). Conclusions: Apoptosis and cell proliferation increased as the grade of tumour increased in ovarian serous adenocarcinoma, suggesting a rapid turnover of the tumour cells in tumours of higher grade, and may play an important role in the growth and the extension of such cancer cells in the peritoneal cavity.     

The O-Linked Glycome and Blood Group Antigens ABO on Mucin-Type Glycoproteins in Mucinous and Serous Epithelial Ovarian Tumors

Background

Mucins are heavily O-glycosylated proteins where the glycosylation has been shown to play an important role in cancer. Normal epithelial ovarian cells do not express secreted mucins, but their abnormal expression has previously been described in epithelial ovarian cancer and may relate to tumor formation and progression. The cyst fluids were shown to be a rich source for acidic glycoproteins. The study of these proteins can potentially lead to the identification of more effective biomarkers for ovarian cancer.

Methods

In this study, we analyzed the expression of the MUC5AC and the O-glycosylation of acidic glycoproteins secreted into ovarian cyst fluids. The samples were obtained from patients with serous and mucinous ovarian tumors of different stages (benign, borderline, malignant) and grades. The O-linked oligosaccharides were released and analyzed by negative-ion graphitized carbon Liquid Chromatography (LC) coupled to Electrospray Ionization tandem Mass Spectrometry (ESI-MSⁿ). The LC-ESI-MSⁿ of the oligosaccharides from ovarian cyst fluids displayed differences in expression of fucose containing structures such as blood group ABO antigens and Lewis-type epitopes.

Results

The obtained data showed that serous and mucinous benign adenomas, mucinous low malignant potential carcinomas (LMPs, borderline) and mucinous low-grade carcinomas have a high level of blood groups and Lewis type epitopes. In contrast, this type of fucosylated structures were low abundant in the high-grade mucinous carcinomas or in serous carcinomas. In addition, the ovarian tumors that showed a high level of expression of blood group antigens also revealed a strong reactivity towards the MUC5AC antibody. To visualize the differences between serous and mucinous ovarian tumors based on the O-glycosylation, a hierarchical cluster analysis was performed using mass spectrometry average compositions (MSAC).

Conclusion

Mucinous benign and LMPs along with mucinous low-grade carcinomas appear to be different from serous and high-grade mucinous carcinomas based on their O-glycan profiles.     

Proteomics advances for precision therapy in ovarian cancer

ABSTRACT

Introduction: Due to the relatively low mutation rate and high frequency of copy number variation, finding actionable genetic drivers of high-grade serous carcinoma (HGSC) is a challenging task. Furthermore, emerging studies show that genetic alterations are frequently poorly represented at the protein level adding a layer of complexity. With improvements in large-scale proteomic technologies, proteomics studies have the potential to provide robust analysis of the pathways driving high HGSC behavior.

Areas covered: This review summarizes recent large-scale proteomics findings across adequately sized ovarian cancer sample sets. Key words combined with ‘ovarian cancer’ including ‘proteomics’, ‘proteogenomic’, ‘reverse-phase protein array’, ‘mass spectrometry’, and ‘adaptive response’, were used to search PubMed.

Expert opinion: Proteomics analysis of HGSC as well as their adaptive responses to therapy can uncover new therapeutic liabilities, which can reduce the emergence of drug resistance and potentially improve patient outcomes. There is a pressing need to better understand how the genomic and epigenomic heterogeneity intrinsic to ovarian cancer is reflected at the protein level and how this information could be used to improve patient outcomes.     

Epigenetic analysis of sporadic and Lynch-associated ovarian cancers reveals histology-specific patterns of DNA methylation

Diagnosis and treatment of epithelial ovarian cancer is challenging due to the poor understanding of the pathogenesis of the disease. Our aim was to investigate epigenetic mechanisms in ovarian tumorigenesis and, especially, whether tumors with different histological subtypes or hereditary background (Lynch syndrome) exhibit differential susceptibility to epigenetic inactivation of growth regulatory genes. Gene candidates for epigenetic regulation were identified from the literature and by expression profiling of ovarian and endometrial cancer cell lines treated with demethylating agents. Thirteen genes were chosen for methylation-specific multiplex ligation-dependent probe amplification assays on 104 (85 sporadic and 19 Lynch syndrome-associated) ovarian carcinomas. Increased methylation (i.e., hypermethylation) of variable degree was characteristic of ovarian carcinomas relative to the corresponding normal tissues, and hypermethylation was consistently more prominent in non-serous than serous tumors for individual genes and gene sets investigated. Lynch syndrome-associated clear cell carcinomas showed the highest frequencies of hypermethylation. Among endometrioid ovarian carcinomas, lower levels of promoter methylation of RSK4, SPARC, and HOXA9 were significantly associated with higher tumor grade; thus, the methylation patterns showed a shift to the direction of high-grade serous tumors. In conclusion, we provide evidence of a frequent epigenetic inactivation of RSK4, SPARC, PROM1, HOXA10, HOXA9, WT1-AS, SFRP2, SFRP5, OPCML, and MIR34B in the development of non-serous ovarian carcinomas of Lynch and sporadic origin, as compared to serous tumors. Our findings shed light on the role of epigenetic mechanisms in ovarian tumorigenesis and identify potential targets for translational applications.     

Epigenetic analysis of sporadic and Lynch-associated ovarian cancers reveals histology-specific patterns of DNA methylation

Diagnosis and treatment of epithelial ovarian cancer is challenging due to the poor understanding of the pathogenesis of the disease. Our aim was to investigate epigenetic mechanisms in ovarian tumorigenesis and, especially, whether tumors with different histological subtypes or hereditary background (Lynch syndrome) exhibit differential susceptibility to epigenetic inactivation of growth regulatory genes. Gene candidates for epigenetic regulation were identified from the literature and by expression profiling of ovarian and endometrial cancer cell lines treated with demethylating agents. Thirteen genes were chosen for methylation-specific multiplex ligation-dependent probe amplification assays on 104 (85 sporadic and 19 Lynch syndrome-associated) ovarian carcinomas. Increased methylation (i.e., hypermethylation) of variable degree was characteristic of ovarian carcinomas relative to the corresponding normal tissues, and hypermethylation was consistently more prominent in non-serous than serous tumors for individual genes and gene sets investigated. Lynch syndrome-associated clear cell carcinomas showed the highest frequencies of hypermethylation. Among endometrioid ovarian carcinomas, lower levels of promoter methylation of RSK4, SPARC, and HOXA9 were significantly associated with higher tumor grade; thus, the methylation patterns showed a shift to the direction of high-grade serous tumors. In conclusion, we provide evidence of a frequent epigenetic inactivation of RSK4, SPARC, PROM1, HOXA10, HOXA9, WT1-AS, SFRP2, SFRP5, OPCML, and MIR34B in the development of non-serous ovarian carcinomas of Lynch and sporadic origin, as compared to serous tumors. Our findings shed light on the role of epigenetic mechanisms in ovarian tumorigenesis and identify potential targets for translational applications.     

Gene expression patterns in ovarian carcinomas

We used DNA microarrays to characterize the global gene expression patterns in surface epithelial cancers of the ovary. We identified groups of genes that distinguished the clear cell subtype from other ovarian carcinomas, grade I and II from grade III serous papillary carcinomas, and ovarian from breast carcinomas. Six clear cell carcinomas were distinguished from 36 other ovarian carcinomas (predominantly serous papillary) based on their gene expression patterns. The differences may yield insights into the worse prognosis and therapeutic resistance associated with clear cell carcinomas. A comparison of the gene expression patterns in the ovarian cancers to published data of gene expression in breast cancers revealed a large number of differentially expressed genes. We identified a group of 62 genes that correctly classified all 125 breast and ovarian cancer specimens. Among the best discriminators more highly expressed in the ovarian carcinomas were PAX8 (paired box gene 8), mesothelin, and ephrin-B1 (EFNB1). Although estrogen receptor was expressed in both the ovarian and breast cancers, genes that are coregulated with the estrogen receptor in breast cancers, including GATA-3, LIV-1, and X-box binding protein 1, did not show a similar pattern of coexpression in the ovarian cancers.