Low-grade and high-grade serous Mullerian carcinoma: review and analysis of publicly available gene expression profiles

Advances in precision therapy of low-grade serous ovarian cancer: A review

Low-grade serous ovarian carcinoma (LGSOC) is a rare subtype of ovarian cancer that accounts for approximately 6% to 10% of serous ovarian cancers. The clinical treatment of LGSOC is similar to that of high-grade serous ovarian carcinoma, however, its clinical and molecular characteristics are different from those of high-grade serous ovarian carcinoma. This article reviews the research on gene diagnosis, surgical treatment, chemotherapy, and biological therapy of LGSOC, providing reference for clinical diagnosis and treatment of LGSOC. Surgery is the cornerstone of LGSOC treatment and maximum effort must be made to achieve R0 removal. Although LGSOC is not sensitive to chemotherapy, postoperative platinum-based combination chemotherapy remains the first-line treatment option for LGSOC. Additional clinical trials are needed to confirm the clinical benefits of chemotherapy and explore new chemotherapy protocols. Hormone and targeted therapies may also play important roles. Some patients, particularly those with residual lesions after treatment, may benefit from hormone maintenance therapy after chemotherapy. Targeted therapies, such as MEKi, show good application prospects and are expected to change the treatment pattern of LGSOC. Continuing to further study the genomics of LGSOC, identify its specific gene changes, and combine traditional treatment methods with precision targeted therapy based on second-generation sequencing may be the direction for LGSOC to overcome the treatment bottleneck. In future clinical work, comprehensive genetic testing should be carried out for LGSOC patients to accumulate data for future scientific research, in order to find more effective methods and drugs for the treatment of LGSOC.

Secondary cytoreductive surgery for recurrent low-grade serous ovarian carcinoma: A systematic review and meta-analysis

OBJECTIVES

Low-grade serous ovarian cancer (LGSC) is a relatively chemo-resistant disease with limited effective treatment options for patients with recurrence. Secondary cytoreductive surgery (SCS) is commonly offered at recurrence, although any benefit this has on survival is not fully determined. This review evaluates the impact of SCS, including residual disease, on progression-free survival (PFS) and overall survival (OS) in recurrent LGSC.

METHODS

A comprehensive search of Medline ALL, Embase Classic + Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Web of Science was conducted to obtain studies evaluating optimal or complete SCS versus suboptimal SCS and the amount of residual disease in recurrent LGSC. Meta-analysis was performed and PFS and OS outcomes were calculated.

RESULTS

1Of 5296 studies screened, 350 progressed to full-text review, with 9 ultimately selected for inclusion in the systematic review. Two studies met criteria for meta-analysis of PFS and of OS. The presence of visible residual disease at the conclusion of SCS negatively impacted PFS (HR = 3.51, 95% CI = 1.72-7.14), whereas SCS with no residual disease significantly improved OS (HR = 0.4, 95% CI = 0.23-0.7) in patients with recurrent LGSC. Diffuse and extensive disease distribution was inversely linked to survival. In addition, SCS as an initial treatment for recurrent LGSC was associated with superior survival in comparison to chemotherapy. A short platinum-free interval was not associated with worse survival in this cohort.

CONCLUSIONS

Complete SCS, and to a lesser extent optimal SCS, are associated with improved PFS and OS in patients with recurrent LGSC. SCS may be a better initial treatment strategy than systemic chemotherapy for recurrent disease. Patients with recurrent LGSC should be evaluated for the role of SCS based on disease distribution and functional status, irrespective of the platinum-free interval. Prospective studies are needed to further study the role of SCS in patients with recurrent LGSC.

Low-grade serous ovarian carcinoma: an evolution toward targeted therapy

Low-grade serous ovarian carcinoma and its high-grade serous ovarian carcinoma counterpart differ in their precursor lesions, molecular profile, natural history, and response to therapies. As such, low-grade serous ovarian carcinoma needs to be studied separately from high-grade serous ovarian carcinoma, despite challenges stemming from its rarity. A deeper understanding of the pathogenesis of low-grade serous ovarian carcinoma and the most common molecular defects and pathways involved in the carcinogenesis of the ovarian epithelium from normal to serous borderline ovarian tumors to low-grade serous ovarian carcinoma will help develop better therapies. By adopting targeted approaches there may be an opportunity to integrate novel therapies without the need for robust numbers in clinical trials. This manuscript will discuss low-grade serous ovarian carcinoma and focus on the arising treatments being developed with an improved understanding of the pathogenesis of this disease.

Identification of modules and hub genes associated with platinum-based chemotherapy resistance and treatment response in ovarian cancer by weighted gene co-expression network analysis

High-grade serous ovarian carcinoma (HGSOC) is the most prevalent and malignant ovarian tumor.To identify co-expression modules and hub genes correlated with platinum-based chemotherapy resistant and sensitive HGSOC, we performed weighted gene co-expression network analysis (WGCNA) on microarray data of HGSOC with 12 resistant samples and 16 sensitive samples of GSE51373 dataset.A total of 5122 genes were included in WGCNA, and 16 modules were identified. Module-trait analysis identified that the module salmon (cor = 0.50), magenta (cor = 0.49), and black (cor = 0.45) were discovered associated with chemotherapy resistant, and the significance for these platinum-resistant modules were validated in the GSE63885 dataset. Given that the black module was validated to be the most related one, hub genes of this module, alcohol dehydrogenase 1B, cadherin 11, and vestigial like family member 3were revealed to be expressional related with platinum resistance, and could serve as prognostic markers for ovarian cancer.Our analysis might provide insight for molecular mechanisms of platinum-based chemotherapy resistance and treatment response in ovarian cancer.

Algorithms Used in Ovarian Cancer Detection: A Minireview on Current and Future Applications

BACKGROUND

Ovarian cancer is the 5th most common cause of cancer death among women in the US. Currently, there is no screening algorithm for asymptomatic women that has been shown to lower mortality rates. Screening is currently not recommended and has been shown to increase harm. Epithelial ovarian cancer (EOC) detection is reviewed, with a focus on high-grade serous, clear-cell, and endometrioid histotypes.

CONTENT

A review of current literature surrounding tools used in detection of ovarian cancer will be presented. CA 125, HE4, risk of ovarian cancer algorithm (ROCA), risk of malignancy algorithm (ROMA), risk of malignancy (RMI), OVA1, and future potential biomarkers are reviewed.

SUMMARY

Screening and early identification of EOC is currently managed as a single disease entity. However, recent evidence has shown ovarian cancer varies with relation to cellular origin, pathogenesis, molecular alterations, and prognosis, depending on histotype. There is a clear need for future studies identifying histotype-specific preclinical tumor markers to aid in detection and improvement of survival rates.

Exploring the Role of Fallopian Ciliated Cells in the Pathogenesis of High-Grade Serous Ovarian Cancer

High-grade serous epithelial ovarian cancer (HGSOC) is the fifth leading cause of cancer death in women and the first among gynecological malignancies. Despite an initial response to standard chemotherapy, most HGSOC patients relapse. To improve treatment options, we must continue investigating tumor biology. Tumor characteristics (e.g., risk factors and epidemiology) are valuable clues to accomplish this task. The two most frequent risk factors for HGSOC are the lifetime number of ovulations, which is associated with increased oxidative stress in the pelvic area caused by ovulation fluid, and a positive family history due to genetic factors. In the attempt to identify novel genetic factors (i.e., genes) associated with HGSOC, we observed that several genes in linkage with HGSOC are expressed in the ciliated cells of the fallopian tube. This finding made us hypothesize that ciliated cells, despite not being the cell of origin for HGSOC, may take part in HGSOC tumor initiation. Specifically, malfunction of the ciliary beat impairs the laminar fluid flow above the fallopian tube epithelia, thus likely reducing the clearance of oxidative stress caused by follicular fluid. Herein, we review the up-to-date findings dealing with HGSOC predisposition with the hypothesis that fallopian ciliated cells take part in HGSOC onset. Finally, we review the up-to-date literature concerning genes that are located in genomic loci associated with epithelial ovarian cancer (EOC) predisposition that are expressed by the fallopian ciliated cells.

Combination of TP53 and AGR3 to distinguish ovarian high-grade serous carcinoma from low-grade serous carcinoma

Ovarian high-grade serous carcinoma (HGSC) and low-grade serous carcinoma (LGSC) are distinct gynecologic neoplasms with diverse pathogenesis and characteristic features. They respond differently to same modalities of treatment protocol and have dissimilar prognosis. Thus, it is essential to obtain accurate differential diagnosis of HGSC and LGSC prior to clinical treatment. In the present study, mRNA expression profiles were generated from 5 HGSC and 6 LGSC specimen using HTSeq, and 699 differentially expressed genes (>2-fold difference) were identified using the DESeq R package. Dendrograms produced by unsupervised hierarchical clustering completely distinguished HGSC from LGSC. Among differentially expressed genes between HGSC and LGSC, anterior gradient homolog 3 (AGR3) was highly upregulated in LGSC compared to HGSC, which was validated by reverse transcription‑quantitative polymerase chain reaction and western blotting. Then, anti‑tumor protein 53 (TP53) and anti-AGR3 immunohistochemistry were performed on 145 HGSC and 30 LGSC samples. Consistent with previous studies, abnormal expression of TP53 (0 or ≥75% positive expression) was observed in 87.6% of HGSC and 13.3% of LGSC samples. Positive staining of AGR3 had a sensitivity of 80.0% and specificity of 89.7% for LGSC. TP53 and AGR3 were both efficient in distinguishing HGSC from LGSC (P<0.001). Receiver operating characteristic analysis revealed a similar area under the curve for AGR3 (0.848) and TP53 (0.871). Through combination of the two markers (TP53 wild‑type pattern and AGR3‑positive expression), the accuracy of differential diagnosis was up to 93.1%. These findings provide compelling evidence that differential diagnosis of HGSC and LGSC can be improved by combined application of these two markers on the basis of conventional histopathological diagnosis.

Epithelial ovarian cancer: the molecular genetics of epithelial ovarian cancer

BACKGROUND

Epithelial ovarian cancer (EOC) remains one of the leading causes of cancer-related deaths among women worldwide, despite gains in diagnostics and treatments made over the last three decades. Existing markers of ovarian cancer possess very limited clinical relevance highlighting the emerging need for identification of novel prognostic biomarkers as well as better predictive factors that might allow the stratification of patients who could benefit from a more targeted approach.

PATIENTS AND METHODS

A summary of molecular genetics of EOC.

RESULTS

Large-scale high-throughput genomic technologies appear to be powerful tools for investigations into the genetic abnormalities in ovarian tumors, including studies on dysregulated genes and aberrantly activated signaling pathways. Such technologies can complement well-established clinical histopathology analysis and tumor grading and will hope to result in better, more tailored treatments in the future. Genomic signatures obtained by gene expression profiling of EOC may be able to predict survival outcomes and other important clinical outcomes, such as the success of surgical treatment. Finally, genomic analyses may allow for the identification of novel predictive biomarkers for purposes of treatment planning. These data combined suggest a pathway to progress in the treatment of advanced ovarian cancer and the promise of fulfilling the objective of providing personalized medicine to women with ovarian cancer.

CONCLUSIONS

The understanding of basic molecular events in the tumorigenesis and chemoresistance of EOC together with discovery of potential biomarkers may be greatly enhanced through large-scale genomic studies. In order to maximize the impact of these technologies, however, extensive validation studies are required.

TXNDC17 promotes paclitaxel resistance via inducing autophagy in ovarian cancer

Paclitaxel is recommended as a first-line chemotherapeutic agent against ovarian cancer, but drug resistance becomes a major limitation of its success clinically. The key molecule or mechanism associated with paclitaxel resistance in ovarian cancer still remains unclear. Here, we showed that TXNDC17 screened from 356 differentially expressed proteins by LC-MS/MS label-free quantitative proteomics was more highly expressed in paclitaxel-resistant ovarian cancer cells and tissues, and the high expression of TXNDC17 was associated with poorer prognostic factors and exhibited shortened survival in 157 ovarian cancer patients. Moreover, paclitaxel exposure induced upregulation of TXNDC17 and BECN1 expression, increase of autophagosome formation, and autophagic flux that conferred cytoprotection for ovarian cancer cells from paclitaxel. TXNDC17 inhibition by siRNA or enforced overexpression by a pcDNA3.1(+)-TXNDC17 plasmid correspondingly decreased or increased the autophagy response and paclitaxel resistance. Additionally, the downregulation of BECN1 by siRNA attenuated the activation of autophagy and cytoprotection from paclitaxel induced by TXNDC17 overexpression in ovarian cancer cells. Thus, our findings suggest that TXNDC17, through participation of BECN1, induces autophagy and consequently results in paclitaxel resistance in ovarian cancer. TXNDC17 may be a potential predictor or target in ovarian cancer therapeutics.

Monoclonal origin of peritoneal implants and lymph node deposits in serous borderline ovarian tumors (s-BOT) with high intratumoral homogeneity

Molecular studies have shown that the most prevalent mutations in serous ovarian borderline tumors (s-BOT) are BRAF and/or KRAS alterations. About one third of s-BOT represent peritoneal implants and/or lymph node involvement. These extraovarian deposits may be monoclonal or polyclonal in origin. To test both the hypotheses, mutational analyses using pyrosequencing for BRAF codon 600 and KRAS codon 12/13 and 61 of microdissected tissue was performed in 15 s-BOT and their invasive and noninvasive peritoneal implants. Two to 6 implants from different peritoneal sites were examined in 13 cases. Lymph node deposits were available for the analysis in 3 cases. Six s-BOT showed mutation in exon 2 codon 12 of the KRAS proto-oncogen. Five additional cases showed BRAF p.V600E mutation representing an overall mutation rate of 73.3%. Multiple (2-6) peritoneal implants were analyzed after microdissection in 13 of 15 cases. All showed identical mutational results when compared with the ovarian site of the disease. All lymph node deposits, including those with multiple deposits in different nodes, showed identical results, suggesting high intratumoral mutational homogeneity. The evidence presented in this study and the majority of data reported in the literature support the hypothesis that s-BOT with their peritoneal implants and lymph node deposits show identical mutational status of BRAF and KRAS suggesting a monoclonal rather than a polyclonal disease regarding these both tested genetic loci. In addition, a high intratumoral genetic homogeneity can be suggested. In conclusion, the results of the present study support the monoclonal origin of s-BOT and their peritoneal implants and lymph node deposits.

BRAF mutation is associated with a specific cell type with features suggestive of senescence in ovarian serous borderline (atypical proliferative) tumors

Serous borderline tumor also known as atypical proliferative serous tumor (APST) is the precursor of ovarian low-grade serous carcinoma (LGSC). In this study, we correlated the morphologic and immunohistochemical phenotypes of 71 APSTs and 18 LGSCs with the mutational status of KRAS and BRAF, the most common molecular genetic changes in these neoplasms. A subset of cells characterized by abundant eosinophilic cytoplasm (EC), discrete cell borders, and bland nuclei was identified in all (100%) 25 BRAF-mutated APSTs but in only 5 (10%) of 46 APSTs without BRAF mutations (P<0.0001). Among the 18 LGSCs, EC cells were found in only 2, and both contained BRAF mutations. The EC cells were present admixed with cuboidal and columnar cells lining the papillae and appeared to be budding from the surface, resulting in individual cells and clusters of detached cells "floating" above the papillae. Immunohistochemistry showed that the EC cells always expressed p16, a senescence-associated marker, and had a significantly lower Ki-67 labeling index than adjacent cuboidal and columnar cells (P=0.02). In vitro studies supported the interpretation that these cells were undergoing senescence, as the same morphologic features could be reproduced in cultured epithelial cells by ectopic expression of BRAF(V600E). Senescence was further established by markers such as SA-β-gal staining, expression of p16 and p21, and reduction in DNA synthesis. In conclusion, this study sheds light on the pathogenesis of this unique group of ovarian tumors by showing that BRAF mutation is associated with cellular senescence and the presence of a specific cell type characterized by abundant EC. This "oncogene-induced senescence" phenotype may represent a mechanism that impedes progression of APSTs to LGSC.

A survival analysis comparing women with ovarian low-grade serous carcinoma to those with high-grade histology

Ovarian low-grade serous carcinoma (LGSC) and high-grade serous carcinoma have distinct molecular profiles, clinical behaviors, and treatment responses. The survival advantage for patients with low-grade carcinoma compared with patients with high-grade histology remains controversial. We retrospectively reviewed the medical charts of 381 patients with ovarian serous carcinoma at Peking Union Medical College Hospital from 2007 to 2010. Patients were classified into two groups according to MD Anderson two-tier system: 35 (9.2%) cases with LGSC and 346 with high-grade serous carcinoma. Patients with low-grade serous ovarian cancer had a significantly younger age at diagnosis (46 versus 56 years, P=0.046), and their median progression-free survival (PFS) and overall survival values were 35.0 and 54.0 months, respectively. A multivariate analysis showed that, for serous ovarian cancer, the histological grade was a significant prognostic factor for PFS but not for overall survival (P=0.022 and P=0.0566, respectively). When stratified by the existence of a residual disease, patients with low-grade disease who underwent cytoreductive surgery without macroscopic residual disease (>1 cm) had a significantly improved median PFS time (36.0 months) compared with that of patients with high-grade carcinoma who received optimal cytoreductive surgery (16.0 months, P=0.017). Conversely, patients with low-grade and high-grade carcinoma who were left with macroscopic residue (>1 cm) experienced a similarly shorter median PFS (10.0 and 13.0 months, respectively, P=0.871). The International Federation of Gynecology and Obstetrics stage and residual disease were significant prognostic factors of low-grade carcinoma, while positive ascites was associated with a worse PFS value. Our data showed that LGSC is a different entity from high-grade carcinoma and that LGSC was associated with improved PFS after optimal cytoreductive surgery but not suboptimal operation.