Abstract
ObjectivesIn view of the recent association of Brn-3 transcription factors with neuroblastomas, cervical, breast, and prostate cancers we examined the expression of Brn-3a(l) in normal ovaries and in different histological grades of ovarian tumors. The expression of Brn-3a(l) was also evaluated in normal ovarian and cancer cell lines and tumor cells isolated from the ascites of advanced-stage ovarian cancer patients.MethodsNormal ovaries, benign, borderline, grades 1, 2 and 3 ovarian tumors were analyzed by immunohistochemistry for Brn-3a(l) expression. A total of 46 ovarian specimens were included in the study. Immunofluorescence was used to investigate the expression of Brn-3a in normal ovarian and cancer cell lines. Brn-3a(l) expression was also evaluated by Western blot in tumor cells isolated from ascites of advanced-stage ovarian cancer patients and also in ovarian cancer cell lines.ResultsNearly 12% of normal and benign ovarian tissues and 57% of borderline ovarian tumors were positive for epithelial Brn-3a(l) expression. Stromal staining was higher and it constituted 40% of normal non-cancerous ovaries compared to 50 and 86% in benign and borderline tumors. On the other hand, 85-100% of grades 1, 2 & 3 ovarian tumors demonstrated nuclear and cytoplasmic Brn-3a(l) staining in the epithelium. Stromal staining in grades1, 2 and 3 tumors constituted 71-88% of total staining. Overall, immunoreactive Brn-3a was present in all grades of ovarian tumors. The extent of epithelial and stromal Brn-3a staining was significantly different between the normal and histological grades of tumors (epithelial-χ2 = 41.01, df = 20, P = 0.004, stromal-χ2 = 24.66. df = 15, P = 0.05). The extent of epithelial staining was significantly higher in grades 1 and 2 ovarian tumors compared to normal ovaries and benign ovarian tumors (p < 0.05). In parallel, stromal staining was significantly higher in grade 3 tumors compared to normal ovaries (p < 0.05). In addition, cytoplasmic and nuclear Brn-3a expression was evident in ovarian cancer cell lines while no such expression was observed in SV40 antigen immortalized normal ovarian cell lines.ConclusionThese data suggest that like other cancers, Brn-3a(l) expression is enhanced in ovarian tumors and its expression is consistent with its known role in inhibiting apoptosis and enhancing tumorigenesis. Specific targeting of Brn-3a may provide a useful strategy for regulating multiple tumor related genes involved with ovarian carcinomas.
Highlights
Epithelial ovarian cancer is the fourth major cause of cancer morbidity and mortality in women
In view of the evidence for the expression of Brn-3a transcription factor in non-neuronal cancer cell types of reproductive origin, we investigated the expression of Brn-3a(l) in normal ovaries and in different histological grades of ovarian carcinomas by immunohistochemistry
Tumor cell cultures were incubated at 37°C in 5% CO2 in growth medium containing 50% Dulbecco Modified Eagle’s Medium (DMEM) (Sigma-Aldrich, Sydney, Australia) and 50% MCDB131 (Invitrogen, CA, USA) supplemented with 10% (v/v) heat inactivated FBS and 2 mM glutamine (Invitrogen CA, USA)
Summary
Epithelial ovarian cancer is the fourth major cause of cancer morbidity and mortality in women. The majority of patients are diagnosed with Stage 3 or 4 disease, when the cancer has spread from the pelvis to the peritoneal cavity and the surrounding organs [2]. Under these circumstances aggressive local tumor growth involving invasion and metastasis occurs which often makes complete surgical removal of the cancer difficult. Better approaches are needed to treat the primary cancer and to inhibit the growth of recurrent disease This can be achieved through a better understanding of the alteration and expression of transcription factors that regulate cellular growth, differentiation and apoptosis
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