Abstract. Rnf2 is a fundamental component of the polycomb repressive complex 1and acts as the really interesting new gene finger E3 ligase, which is responsible for histone 2A modification. Previous studies have shown that the ring finger protein 2 (Rnf2) is overexpressed in various types of tumor and has a close association with tumor development. However, few studies have been carried out into the expression and biological function of Rnf2 in gastric cancer cells. The present study measured the expression of Rnf2 in gastric cancer cells and normal epithelial gastric cells. The results demonstrate that Rnf2 is upregulated in gastric cancer cells. In addition, the knockdown of Rnf2 inhibited the cell viability and induced increased G1 phase followed by a substantial reduction of the G2/M phase. The expression levels of p21 and p27 were also significantly elevated by the knockdown of Rnf2. These results provide evidence of the oncogenic function of Rnf2 in gastric cancer, possibly through an inhibition of cellular proliferation and a delay of the G2/M phase. Therefore, Rnf2 may be a novel target for the prognosis and therapy of gastric cancer.
IntroductionPolycomb group (PcG) proteins are epigenetic regulators for gene silencing at the transcription level, acting as important regulators of DNA repair, proliferation, embryonic differentiation and cell-fate maintenance during development and in adult tissue homeostasis (1-3). These proteins exist in at least two biochemically and functionally distinct PcG core complexes referred to as polycomb repressive complex (PRC) 1 and 2. PRC2, which is involved in the initiation of gene repression, mediates the trimethylation of histone H3 at Lys27 (H3K27me3) and consists of histone methyltransferase enhancer of zeste homolog 2 (EZH2), the polycomb repressive complex and embryonic ectoderm development (4,5). The mammalian PRC1, which is an ubiquitin E3 ligase complex, consists of polycomb (PC), polyhomeotic (PH), BMI1, ring finger protein (Rnf) 1A and 2 (Rnf2) (6), among which Rnf2 has been identified as the catalytic subunit (7). Rnf2, acts as the RING finger E3 ligase responsible for H2A modification in the PRC1 complex and influences early development and embryonic stem cell maintenance as well as cancer development (8,9). Recent evidence showed that Rnf2 is highly expressed in various types of tumor in comparison to normal tissue counterparts (10). Knockdown of Rnf2 in HeLa cells resulted in morphological changes and an inhibition of cellularproliferation (7), suggesting an oncogenic function of Rnf2. Additionally, it has been reported that Rnf2 can either directly or indirectly target a distinct, specific pathway involved in cell cycle control (11,12). However, in order to acquire a complete understanding of the mechanisms through which cancer progression is regulated by Rnf2, additional investigation is required.Normal cell cycle progression is tightly controlled by a variety of molecular checkpoints, which supervise the biological processes that take place in different...