Ovarian Cancer Biomarker Screening: Still Too Early to Tell

Discovery of potential serum and urine-based microRNA as minimally-invasive biomarkers for breast and gynecological cancer

BACKGROUND

Deregulated microRNAs (miRNAs) in breast and gynecological cancer might contribute to improve early detection of female malignancies.

OBJECTIVE

Specification of miRNA types in serum and urine as minimally-invasive biomarkers for breast (BC), endometrial (EC) and ovarian cancer (OC).

METHODS

In a discovery phase, serum and urine samples from 17 BC, five EC and five OC patients vs. ten healthy controls (CTRL) were analyzed with Agilent human miRNA microarray chip. Selected miRNA types were further investigated by RT-qPCR in serum (31 BC, 13 EC, 15 OC patients, 32 CTRL) and urine (25 BC, 10 EC, 10 OC patients, 30 CTRL) applying two-sample t-tests.

RESULTS

Several miRNA biomarker candidates exhibited diagnostic features due to distinctive expression levels (serum: 26; urine: 22). Among these, miR-518b, -4719 and -6757-3p were found specifically deregulated in BC serum. Four, non-entity-specific, novel biomarker candidates with unknown functional roles were identified in urine (miR-3973; -4426; -5089-5p and -6841). RT-qPCR identified miR-484/-23a (all p⩽ 0.001) in serum as potential diagnostic markers for EC and OC while miR-23a may also serve as an endogenous control in BC diagnosis.

CONCLUSIONS

Promising miRNAs as liquid biopsy-based tools in the detection of BC, EC and OC qualified for external validation in larger cohorts.

The expression of FAS-associated factor 1 and heat shock protein 70 in ovarian cancer

OBJECTIVE

In this study, we evaluated the expression of FAS-associated factor 1 (FAF1) and heat shock protein 70 (HSP70) in normal ovary and ovarian cancer, and also analyzed the correlation between FAF1 and HSP70 in ovarian cancer.

METHODS

The patient group consisted of 29 unrelated Korean women diagnosed as ovarian cancers and control samples were obtained from 7 patients who underwent oophorectomy for benign disease of uterus, and normal ovary was confirmed histologically from biopsy. We examined FAF1 and HSP70 expression by western blot analysis and immunohistochemical staining in normal ovary and ovarian cancer. Furthermore, we examined a correlation between FAF1 and HSP70 in ovarian cancer.

RESULTS

The expression of FAF1 was lower in ovarian cancer than that in normal ovary (P=0.02), and the expression of HSP70 was increased in ovarian cancer in comparison to that in normal ovary (P=0.03). The expression of FAF1 was decreased in advanced stages (stage III or stage IV) as compared with early stages (stage I or stage II) (P=0.01). The expression of HSP70 was not significantly related with ovarian cancer histology (P=0.10), but the expression of HSP70 was most increased with papillary serous carcinomas and undifferentiated ovarian cancer. The expression of FAF1 was inversely correlated with the expression of HSP70 in ovarian cancer (Spearman correlation coefficience=-0.47).

CONCLUSION

We concluded that the expression of FAF1 or HSP70 each seems to have a meaning as a biomarker for early detection of ovarian cancer. The expressions of FAF1 and HSP70 seem to be more valuable in predicting ovarian cancer when used together because of their inverse correlation. This is the first study about the expression of FAF1 in ovarian cancer and the correlation between FAF1 and HSP70 expression in ovarian cancer.

Expression and clinical significance of BIRC6 in human epithelial ovarian cancer

Baculoviral IAP repeat containing 6 (BIRC6), an unusually large member of the IAP family, may play an important role in oncogenesis. The aim of this study was to assess the value of BIRC6 in predicting tumor recurrence after curative resection in epithelial ovarian cancer (EOC) patients. In this study, the differences of BIRC6 expression in four paired EOC and normal tissue were performed by Western blot, and expression of BIRC6 protein was analyzed in 100 clinicopathologically characterized EOC cases from those who underwent curative resection between 2003 and 2011 by immunohistochemistry. Kaplan-Meier survival estimates and log-rank tests were used to assess the prognostic significance. It was found that BIRC6 expression was higher in the carcinoma tissue than in normal control tissue at protein level by Western blot. There was a significant difference of BIRC6 expression in patients categorized according to tumor differentiation (p = 0.016). Univariate analyses and multivariate analyses revealed that BIRC6 was an independent significant predictor for overall survival and disease-free survival. A prognostic significance of BIRC6 was also found by Kaplan-Meier method. The expression of BIRC6 in the cytoplasm is associated with EOC differentiation and may be a novel predictor for poor prognosis of EOC patients after curative resection.

Microvesicles as potential ovarian cancer biomarkers

Although the incidence of ovarian cancer is low (i.e., less than 5% in European countries), it is the most lethal gynecologic malignancy and typically has a poor prognosis. To ensure optimal survival, it is important to diagnose this condition when the pathology is confined to the ovary. However, this is difficult to achieve because the first specific symptoms appear only during advanced disease stages. To date, the biomarker mainly used for the diagnosis and prognosis of ovarian cancer is CA125; however, this marker has a low sensitivity and specificity and is associated with several other physiological and pathological conditions. No other serum ovarian cancer markers appear to be able to replace or complement CA125, and the current challenge is therefore to identify novel markers for the early diagnosis of this disease. For this purpose, studies have focused on the microvesicles (MVs) released from tumor cells. MVs may represent an ideal biomarker because they can be easily isolated from blood, and they have particular features (mainly regarding microRNA profiles) that strongly correlate with ovarian cancer stage and may be effective for early diagnosis.

Prognostic biomarkers in ovarian cancer

Epithelial ovarian cancer (EOC) remains the most lethal gynecological malignancy despite several decades of progress in diagnosis and treatment. Taking advantage of the robust development of discovery and utility of prognostic biomarkers, clinicians and researchers are developing personalized and targeted treatment strategies. This review encompasses recently discovered biomarkers of ovarian cancer, the utility of published prognostic biomarkers for EOC (especially biomarkers related to angiogenesis and key signaling pathways), and their integration into clinical practice.

Proteomics and biomarkers for ovarian cancer diagnosis

Ovarian cancer remains a leading cause of death from gynecological malignancy. Early diagnosis is the most important determinant of survival. Current diagnostic tools have had very limited success in early detection. In recent years, the advancing techniques for proteomics have accelerated the discovery of ovarian cancer biomarkers. Numerous proteomics-based molecular biomarkers/panels have been identified and hold great potential for diagnostic applications, but they need further development and validation. This article reviews recently published data on the diagnosis of ovarian cancer with proteomics, including the major proteomics technologies and promising strategies for biomarker discovery and development.