MP92-18 GOLPH3 IS OVEREXPRESSED AND CONTRIBUTES TO APOPTOTIC-RESISTANCE AND METASTASIS IN RENAL CELL CARCINOMA

Abstract

INTRODUCTION AND OBJECTIVES: The enhancer of zeste homolog 2 (EZH2) gene has been recognized as a proto-oncogene and linked to human malignancies. Here, we determined EZH2 expression in primary renal cell carcinoma (RCC) specimens and explored its potential role in prosurvival and metastasis of RCC. METHODS: EZH2 protein expression in RCC specimens was determined by immunohistochemistry. siRNA targeting EZH2 were transfected into RCC CaKi-2, 786-O, and 769-P cells. Cell cycle and apoptosis were detected by flow cytometry following EZH2 knockdown. Transwell assay were used to determine invasive potential in response to EZH2 inhibition. Western blot was performed to detect the expression of cell cycle and apoptosis associated proteins. RESULTS: EZH2 was higher expressed in RCC sample than in paired adjacent nontumorous tissue. 76.5% of RCC sample showed dense staining of EZH2, whereas the neighboring unaffected cells stained at the normal level. After RCC cells were transfected with siRNA targeting to EZH2, all three cells were arrested in G1/S phase (P 0.05, compared to control siRNA transfected cells). In addition, significant increased apoptosis were observed in the three cell lines following EZH2 silencing (P 0.05, compared to control cells). Furthermore, inhibition of EZH2 resulted in decreased invasive capability of RCC cells in vitro. Mechanically, EZH2 knockdown led to upregulation of p21, cleaved caspase-9, -3, and PARP. Downregulation of PCNA and MMP-2 was also observed following EZH2 silencing. CONCLUSIONS: EZH2 is overexpressed in RCC. Moreover, it plays a critical role in both proliferation and apoptotic-resistance in RCC cell lines. In addition, EZH2 can enhance invasive potential of RCC cell in vitro. These data suggest that inhibition of EZH2 could provide an advantage in improving therapeutic effect of RCC.