EZH2 Expression Correlates with Increased Angiogenesis in Ovarian Carcinoma.
Bassam Albashiti, Anil Sood, Sudeshna Bandyopadhyay, Asaad Semaan, Adnan Munkarah, Yaser Hussein, Quratulain Ahmed, Robert Morris, Rouba Ali-Fehmi. Wayne State Universty, Detroit, MI; Henry Ford Hospital, Detroit; MD Anderson Cancer Center, Houston, TX
Background: We recently discovered EZH2, a polycomb repressor, to have substantially increased expression in tumor endothelial cells. In this study, we examined the clinical and functional significance of EZH2 and its correlation with VEGF and angiogenesis in ovarian carcinoma.
Design: Cell lines: Mouse ovarian endothelial cells (MOEC) were transfected with the Renilla luciferase plasmid either with or without the EZH2 promoter construct. Cells were then treated with VEGF [conditioned media from SKOV3 ovarian cancer cells (SKOV3-CM)]. EZH2 mRNA was quantified using real time RT-PCR. EZH2 protein levels were evaluated by western blot.
(IHC): 180 paraffin-embedded epithelial ovarian cancer specimens (collected between 1985 – 2004) with available clinical outcome data were identified. IHC for EZH2, CD34, and VEGF was performed. For EZH2 and VEGF, the stained slides were scored based on intensity and percentage of cells stained and categorized as high and low expressors. To quantify micro vessel density (MVD), the number of blood vessels staining positive for CD34 was recorded in 10 high power fields and mean calculated.
Also, clinical parameters and survival data was obtained on these patients from the clinical information system and SEER registry.
Results: In the MOEC cell lines, there was a significant increase in EZH2 promoter activity and EZH2 mRNA expression levels in endothelial cells in response to VEGF (SKOV3-CM). This increases in EZH2 promoter activity and mRNA was blocked with the VEGFR2 specific antibody DC101. Similarly, increased EZH2 protein levels in response to VEGF was blocked by the anti-VEGFR2 antibody.By IHC, EZH2 expression was evaluated in 180 cases in both tumor and endothelial compartments (EZH2-Tand EZH2-E). 66% and 67% of the samples showed high EZH-2 expression in the tumor and endothelial compartments respectively. High expression of EZH2-T and EZH2-E was significantly associated with high-stage (p < 0.001) and high-grade (p < 0.05) disease. High EZH2-T and EZH2-E was also significantly associated with decreased overall survival (median 2.5 years vs. 7.33 years, p < 0.001) and (2.33 vs. 8.33 years, p < 0.001) respectively.Tumors with high VEGF expression had significantly correlation with high EZH2-E expression (p < 0.001). Moreover, tumors with high EZH2-E expression also had significantly greater MVD (p < 0.001).
Conclusions: These findings suggest that EZH2 may be a regulator of tumor angiogenesis and supports the possibility of this being a therapeutic target in ovarian carcinoma.
Category: Gynecologic & Obstetrics
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 105, Tuesday Afternoon