Characterization of the gene structure, functional significance, and clinical application of RNF180, a novel gene in gastric cancer

Abstract

BACKGROUND: By using genome‐wide methylation screening, the authors identified ring finger protein 180 (RNF180) as preferentially methylated in cancer. This study was undertaken to clarify its structure and functional role in gastric cancer. METHODS: The transcription start site and core functional promoter region of RNF180 were revealed by 5′ rapid amplification of cDNA ends and luciferase activity assays. Promoter methylation was detected by combined bisulfite restriction analysis and bisulfite genomic sequencing. Cell growth was detected by colony formation assay, apoptosis by annexin V assay, and RNF180 target genes by cDNA microarray. RESULTS: The authors revealed the transcription start site of RNF180 gene and identified the functional core promoter region (−202/+372) in the CpG island, which could be silenced by in vitro methylation assay. RNF180 was silenced in 6 of 7 gastric cancer cell lines and significantly down‐regulated in primary gastric cancers compared with adjacent normal tissues (P = .001). Loss of gene expression was associated with promoter methylation. Re‐expression of RNF180 suppressed cell growth (P < .001) and induced apoptosis (P < .05), which were mediated by up‐regulating the antiproliferation regulators MTSS1 and CDKN2A and the proapoptotic mediator TIMP3. Promoter methylation of RNF180 was detected in 76% (150 of 198) of primary gastric cancers and 55% (11 of 20) of intestinal metaplasia, but in none of 23 normal gastric tissues. Methylated RNF180 DNA was detected in the plasma of 56% of gastric cancer patients, but not in healthy controls (P = .003). Patients with low or loss of RNF180 expression had significantly poorer overall survival. CONCLUSIONS: RNF180 is a novel potential tumor suppressor in gastric carcinogenesis and has potential clinical utility as a biomarker for gastric cancer patients. Cancer 2012;. © 2011 American Cancer Society.

Epigenetic silencing of GDF1 disrupts SMAD signaling to reinforce gastric cancer development

“…To this end, we have previously conducted extensive research and discovered an array of molecular regulators associated with stomach cancer development. [13][14][15][23][24][25] In particular, we recently demonstrated a causal relationship between H. pylori infection and aberrant DNA methylation in the host genome by cross-species epigenomics analysis, and revealed that epigenetic silencing of the antitumorigenic transcriptional regulator FOXD3 is a major mechanism responsible for the H. pylori-induced gastric carcinogenesis. 16,17 Here we provide new evidence that GDF1, which functions to protect gastric epithelial cells against malignant transformation by upholding SMAD signaling (Figures 3 and 4), is also susceptible to epigenetic silencing in the majority of mouse and human gastric cancers (Figures 1, 2 and 5).…”

DNA Methylation as a Molecular Biomarker in Gastric Cancer

“…A number of studies have investigated the utility of measuring serum or plasma DNA methylation to detect DNA methylation from tumor-derived circulating DNA as a potential molecular diagnostic marker for GC. Methylation of p16, CDH1, MGMT, RARB and RNF180 are significantly higher in DNA from serum or plasma from GC subjects than in that from control subjects [81][82][83][84]. Methylation of the CDH1 promoter in preoperative peritoneal washes is also significantly associated with more aggressive clinicopathological subtypes of GC, including larger tumors, infiltration type, lymphatic and venal invasion, higher T stage, lymph node and distant metastasis and worse disease-free survival [85].…”

Targeting ribonucleotide reductase M2 subunit by small interfering RNA exerts anti-oncogenic effects in gastric adenocarcinoma

“…Enhancing our understanding of the carcinogenetic process (4) and exploring new treatment options are important to improve the outlook of gastric cancer patients. Gastric carcinogenesis is a multistep process involving genetic and epigenetic alterations of protein-coding proto-oncogenes (5) and tumor-suppressor genes (6)(7). In addition, recent studies have demonstrated the involvement of microRNAs (8) and emerging evidence underscores the importance of signaling pathways such as NF-κB, Wnt/β-catenin signaling and Notch signaling involved in the gastric cancer development (9).…”