A new model of ovarian carcinogenesis may influence early detection strategies

Cancerous inhibitor of protein phosphatase 2A regulates cisplatin resistance in ovarian cancer

Ovarian cancer is the most aggressive type of gynecological cancer. The cause of the poor survival rate is the development of chemotherapy resistance to platinum-based therapies, including cisplatin. The present study aimed to investigate the mechanism of cancerous inhibitor of protein phosphatase 2A (CIP2A)-induced chemoresistance in ovarian cancer. The present study initially investigated the expression of CIP2A in the ovarian tumor tissue, cisplatin-sensitive SKOV-3 cell line, and cisplatin-resistant ovarian carcinoma SKOV-3CDDP/R cell line. In addition, CIP2A was knocked down using small interference RNA in ovarian cancer cells and the chemosensitivity of these cells was analyzed. The results demonstrated that CIP2A expression was significantly higher in patients with ovarian cancer and in the cisplatin-resistant ovarian carcinoma SKOV-3CDDP/R cell line at the mRNA and protein levels. The proliferation and chemosensitivity were decreased and enhanced, respectively, when CIP2A was knocked down. CIP2A silencing significantly promoted the apoptosis induced by cisplatin in SKOV-3CDDP/R cells, suggesting that CIP2A participated in the cisplatin resistance of ovarian cancer cells and that CIP2A silencing enhanced the apoptosis induced by cisplatin. CIP2A may be considered as a potential candidate for modulating cisplatin therapy in ovarian cancer.

Time to diagnosis of Type I or II invasive epithelial ovarian cancers: a multicentre observational study using patient questionnaire and primary care records

OBJECTIVE

To compare time to diagnosis of the typically slow-growing Type I (low-grade serous, low-grade endometrioid, mucinous, clear cell) and the more aggressive Type II (high-grade serous, high-grade endometrioid, undifferentiated, carcinosarcoma) invasive epithelial ovarian cancer (iEOC).

DESIGN

Multicentre observational study.

SETTING

Ten UK gynaecological oncology centres.

POPULATION

Women diagnosed with primary EOC between 2006 and 2008.

METHODS

Symptom data were collected before diagnosis using patient questionnaire and primary-care records. We estimated patient interval (first symptom to presentation) using questionnaire data and diagnostic interval (presentation to diagnosis) using primary-care records. We considered the impact of first symptom, referral and stage on intervals for Type I and Type II iEOC.

MAIN OUTCOME MEASURES

Patient and diagnostic intervals.

RESULTS

In all, 78% of 60 Type I and 21% of 134 Type II iEOC were early-stage. Intervals were comparable and independent of stage [e.g. median patient interval for Type I: early-stage 0.3 months (interquartile range 0.3-3.0) versus late-stage 0.3 months (interquartile range 0.3-4.5), P = 0.8]. Twenty-seven percent of women with Type I and Type II had diagnostic intervals of at least 9 months. First symptom (questionnaire) was also similar, except for the infrequent abnormal bleeding (Type I 15% versus Type II 4%, P = 0.01). More women with Type I disease (57% versus 41%, P = 0.04) had been referred for suspected gynaecological cancer. Median time from referral to diagnosis was 1.4 months for women with iEOC referred via a 2-week cancer referral to any specialty compared with 2.6 months (interquartile range 2.0-3.7) for women who were referred routinely to gynaecology.

CONCLUSION

Overall, shorter diagnostic delays were seen when a cancer was suspected, even if the primary tumour site was not recognised to be ovarian. Despite differences in carcinogenesis and stage for Type I and Type II iEOC, time to diagnosis and symptoms were similar. Referral patterns were different, implying subtle symptom differences. If symptom-based interventions are to impact on ovarian cancer survival, it is likely to be through reduced volume rather than stage-shift. Further research on histological subtypes is needed.

TWEETABLE ABSTRACT

No difference in time to diagnosis for Type I versus Type II invasive epithelial ovarian cancers.

Overexpression of forkhead box protein M1 (FOXM1) in ovarian cancer correlates with poor patient survival and contributes to paclitaxel resistance

Aim

Deregulation of FOXM1 has been documented in various cancers. The aim of this study was to evaluate the role of FOXM1 in ovarian cancer tumorigenesis and paclitaxel resistance.

Experimental Design

Expression of FOXM1 was examined in 119 clinical samples by immunohistochemistry and correlated with clinicopathological parameters. Effects of FOXM1 knockdown on ovarian cancer cell migration, invasion and mitotic catastrophe were also studied. qPCR and ChIP-qPCR were used to establish KIF2C as a novel FOXM1 target gene implicated in chemoresistance.

Results

High nuclear FOXM1 expression in ovarian cancer patient samples was significantly associated with advanced stages (P = 0.035), shorter overall (P = 0.019) and disease-free (P = 0.014) survival. Multivariate analysis confirmed FOXM1 expression as an independent prognostic factor for ovarian cancer. FOXM1 knockdown significantly inhibited migration and invasion of ovarian cancer cells and enhanced paclitaxel-mediated cell death and mitotic catastrophe in a p53-independent manner. Bioinformatics analysis suggested a number of potential transcription targets of FOXM1. One of the potential targets, KIF2C, exhibited similar expression pattern to FOXM1 in chemosensitive and chemoresistant cells in response to paclitaxel treatment. FOXM1 could be detected at the promoter of KIF2C and FOXM1 silencing significantly down-regulated KIF2C.

Conclusion

Our findings suggest that FOXM1 is associated with poor patient outcome and contributes to paclitaxel resistance by blocking mitotic catastrophe. KIF2C is identified as a novel FOXM1 transcriptional target that may be implicated in the acquisition of chemoresistance. FOXM1 should be further investigated as a potential prognostic marker and therapeutic target for ovarian cancer.

Assessment of symptomatic women for early diagnosis of ovarian cancer: results from the prospective DOvE pilot project

BACKGROUND

Around 90% of deaths from ovarian cancer are due to high-grade serous cancer (HGSC), which is frequently diagnosed at an advanced stage. Several cancer organisations made a joint recommendation that all women with specified symptoms of ovarian cancer should be tested with the aim of making an early diagnosis. In the Diagnosing Ovarian Cancer Early (DOvE) study we investigated whether open-access assessment would increase the rate of early-stage diagnosis.

METHODS

Between May 1, 2008, and April 30, 2011, we enrolled women who were aged 50 years or older and who had symptoms of ovarian cancer. They were offered diagnostic testing with cancer antigen (CA-125) blood test and transvaginal ultrasonography (TVUS) at a central and a satellite open-access centre in Montreal, QC, Canada. We compared demographic characteristics of DOvE patients with those of women in the same age-group in the general population of the area, and compared indicators of disease burden with those in patients with ovarian cancer referred through the usual route to our gynaecological oncology clinic (clinic patients).

FINDINGS

Among 1455 women assessed, 402 (27·6%) were in the highest-risk age group (≥ 65 years). 239 (16·4%) of 1455 required additional investigations. 22 gynaecological cancers were diagnosed, 11 (50%) of which were invasive ovarian cancers, including nine HGSC. The prevalence of invasive ovarian cancer, therefore, was one per 132 women (0·76%), which is ten times higher than that reported in screening studies. DOvE patients were significantly younger, more educated, and more frequently English speakers than were women in the general population. They also presented with less tumour burden than did the 75 clinic patients (median CA-125 concentration 72 U/mL, 95% CI 12-1190 vs 888 U/mL, 440-1936; p=0·010); Eight (73%) tumours were completely resectable in DOvE patients, compared with 33 (44%) in clinic patients (p=0·075). Seven (78%) of the HGSC in the DOvE group originated outside the ovaries and five were associated with only slightly raised CA-125 concentrations and minimal or no ovarian abnormalities on TVUS.

INTERPRETATION

The proportion of HGSC that originated outside the ovaries in this study suggests that early diagnosis programmes should aim to identify low-volume disease rather than early-stage disease, and that diagnostic approaches should be modified accordingly. Although testing symptomatic women may result in earlier diagnosis of invasive ovarian cancer, large-scale implementation of this approach is premature.

FUNDING

Canadian Institutes of Health Research, Montreal General Hospital Foundation, Royal Victoria Hospital Foundation, Cedar's Cancer Institute, and La Fondation du Cancer Monique Malenfant-Pinizzotto.

Ovarian cancer development and metastasis

The biology of ovarian carcinoma differs from that of hematogenously metastasizing tumors because ovarian cancer cells primarily disseminate within the peritoneal cavity and are only superficially invasive. However, since the rapidly proliferating tumors compress visceral organs and are only temporarily chemosensitive, ovarian carcinoma is a deadly disease, with a cure rate of only 30%. There are a number of genetic and epigenetic changes that lead to ovarian carcinoma cell transformation. Ovarian carcinoma could originate from any of three potential sites: the surfaces of the ovary, the fallopian tube, or the mesothelium-lined peritoneal cavity. Ovarian cacinoma tumorigenesis then either progresses along a stepwise mutation process from a slow growing borderline tumor to a well-differentiated carcinoma (type I) or involves a genetically unstable high-grade serous carcinoma that metastasizes rapidly (type II). During initial tumorigenesis, ovarian carcinoma cells undergo an epithelial-to-mesenchymal transition, which involves a change in cadherin and integrin expression and up-regulation of proteolytic pathways. Carried by the peritoneal fluid, cancer cell spheroids overcome anoikis and attach preferentially on the abdominal peritoneum or omentum, where the cancer cells revert to their epithelial phenotype. The initial steps of metastasis are regulated by a controlled interaction of adhesion receptors and proteases, and late metastasis is characterized by the oncogene-driven fast growth of tumor nodules on mesothelium covered surfaces, causing ascites, bowel obstruction, and tumor cachexia.