Expression of Stem Cell Markers in Preinvasive Tubal Lesions of Ovarian Carcinoma

SOX2 is a promising predictor of relapse and death in advanced stage high-grade serous ovarian cancer patients with residual disease after debulking surgery

The transcription factor SOX2 is a well-established and important stem cell marker. Its role in cancer biology remains unclear, but it has been proposed to also be a marker of cancer stem cells. We investigated the role of SOX2 protein expression in women with high-grade serous ovarian cancer (HGSOC) to determine its potential prognostic and treatment predictive value. We constructed a tissue microarray of 130 advanced stage HGSOC tumors with an average of 6 cores each, stained for SOX2 protein expression and evaluated survival outcomes. We also treated two HGSOC cell lines with carboplatin and paclitaxel and measured SOX2 expression by RT-PCR and immunoblotting at different doses and time-points. Among patients with non-radical debulking surgery overall and progression-free survival were shorter for patients with SOX2 positive tumors (mean 26 vs. 39 months, log-rank test: p = .0076, and mean 14 vs. 19 months, p = .055, respectively). Knockdown of SOX2 in cell lines did not affect growth inhibition following chemotherapy treatment. Our results show that SOX2 has a strong prognostic potential among HGSOC patients with residual tumor tissue after debulking surgery and suggest that SOX2 expressing cells remaining after non-radical debulking surgery may constitute a subpopulation of cancer stem cells with greater tumor-initiating potential.

Novel protein and immune response markers of human serous tubal intraepithelial carcinoma of the ovary

Ovarian cancer is the leading cause of death among gynecologic diseases in the USA and Europe. High-grade serous carcinoma (HGSC) of the ovary, the most aggressive type of ovarian cancer, is typically diagnosed at advanced stages when the 5-year survival is dismal. Since the cure rate for stage I HGSC is high, early detection of localized initial disease may improve patient outcomes. Serous tubal intraepithelial carcinoma (STIC) is considered to be a precursor lesion of HGSC. Discovery of biomarkers associated with STIC could aid in the development of an HGSC screening algorithm. Using immunohistochemical staining, we have demonstrated overexpression of UCHL1, ADAMTS13, and GAPDH in patients' STIC lesions, but not in cancer-free fallopian tubes. We additionally demonstrated a marked increase of T cells in perineoplastic stroma surrounding STIC lesions (largely CD4 + cells), but not in normal fallopian tubes and HGSC. FOXP3 + T regulatory cells are absent in STIC lesions but are present in HGSC. These observations indicate the microenvironment surrounding a STIC lesion may be immune promoting in contrast to the immune suppressive microenvironment of invasive carcinoma. In summary, we have identified UCHL1, ADAMTS13, and GAPDH as novel potentially useful markers associated with early stages of HGSC tumorigenesis and possibly contribute to STIC immunogenicity. The lack of immune suppression in the STIC microenvironment indicates that the immune system can still recognize and keep STIC controlled at this stage of the tumor development.

PAX2 maintains the differentiation of mouse oviductal epithelium and inhibits the transition to a stem cell-like state

Recent studies have provided evidence that the secretory cells of the fallopian tube (oviduct) are a probable origin for high-grade serous ovarian carcinoma. In addition to secretory cells, the fallopian tube epithelium consists of ciliated cells and CD44+ undifferentiated stem-like cells. Loss of PAX2 expression is recognized as an early event in epithelial transformation, but the specific role of PAX2 in this transition is unknown. The aim of this study was to define the role of PAX2 in oviductal epithelial (OVE) cells and its response to transforming growth factor β1 (TGFβ), characterizing specifically its potential involvement in regulating stem cell-like behaviors that may contribute to formation of cancer-initiating cells. Treatment of primary cultures of mouse OVE cells with TGFβ induced an epithelial-mesenchymal transition (EMT) associated with decreased expression of PAX2 and an increase in the fraction of cells expressing CD44. PAX2 knockdown in OVE cells and overexpression in ovarian epithelial cells confirmed that PAX2 inhibits stem cell characteristics and regulates the degree of epithelial differentiation of OVE cells. These results suggest that loss of PAX2, as occurs in serous tubal intraepithelial carcinomas, may shift secretory cells to a more mesenchymal phenotype associated with stem-like features.

Overexpression of the cancer stem cell marker CD117 predicts poor prognosis in epithelial ovarian cancer patients: evidence from meta-analysis

Purpose

Cancer stem cells have recently been identified as a key driving factor for tumor metastasis and chemoresistance. CD117 is a well-established cancer stem cell marker, but its clinical significance in epithelial ovarian cancer (EOC) remains controversial. Therefore, we aimed to identify correlations between CD117 expression and clinical features and outcomes in EOC patients in this meta-analysis.

Materials and methods

A literature search was performed in the PubMed, Cochrane Library, Web of Science, EMBASE, and OVID databases to identify eligible studies. Correlations between CD117 expression and clinicopathological parameters and overall survival or disease-free survival were analyzed. A subgroup analysis was then performed, which was classified by patient ethnicity and age at diagnosis, study sample size, and tumor histological type.

Results

A total of seven studies enrolling 1,247 EOC patients were included in this meta-analysis. Our results demonstrated that CD117 expression was significantly correlated with age (pooled odds ratio [OR] =1.67, 95% confidence interval [CI] =1.05–2.66), International Federation of Gynecology and Obstetrics stage (pooled OR =1.99, 95% CI =1.31–3.02), tumor differentiation grade (pooled OR =2.46, 95% CI =1.48–4.10), and histological type (pooled OR =1.85, 95% CI =1.05–3.26). EOC patients with high CD117 expression had significantly worse OS (hazard ratio [HR] =1.39, 95% CI =1.03–1.90) than patients with low CD117 expression. However, no significant correlation was found between CD117 expression and disease-free survival (HR =1.31, 95% CI =0.79–2.17). In subgroup analysis, CD117 was identified as a significant prognostic factor for overall survival in European patients (HR =1.59, 95% CI =1.13–2.23), younger patients (<60 years) (HR =1.59, 95% CI =1.10–2.30), studies with sample sizes >200 (HR =1.84, 95% CI =1.32–2.56), and the mixed histological types (HR =1.47; 95% CI =1.08–2.00).

Conclusion

Our meta-analysis suggests that CD117 is associated with EOC progression and can serve as a promising prognostic predictor for EOC patients. However, larger scale multicenter clinical trials are still needed to further validate our results.