Hypermethylation of the RASSF1A gene promoter as the tumor DNA marker for nasopharyngeal carcinoma

Background RASSF1A is a tumor suppressor gene. The methylation of RASSF1A has been reported to be associated with nasopharyngeal tumorigenesis. However, the heterogeneity was high among different studies. A meta-analysis was performed to evaluate the value of RASSF1A methylation for the diagnosis and early screening of nasopharyngeal carcinoma. Methods Relevant articles were identified by searching the MEDLINE database. Frequency and odds ratio (OR) were applied to estimate the effect of CDH-1 methylation based on random-/fixed-effect models. The meta-analysis was performed by using MedCalc® software. Subgroup analyses were performed by test method, ethnicity, and source of nasopharyngeal carcinoma samples to determine likely sources of heterogeneity. Results A total of 17 studies, including 1688 samples (1165 nasopharyngeal carcinoma samples, and 523 from non-cancerous samples) were used for the meta-analysis. The overall frequencies of RASSF1A methylation were 59.68% and 2.65% in case-group and control-group, respectively. By removing the poor relative studies, the heterogeneity was not observed among the studies included. The association between RASSF1A gene methylation and the risk of nasopharyngeal carcinoma was also confirmed by calculating the OR value of 30.32 (95%CI = 18.22–50.47) in the fixed-effect model (Q = 16.41, p = 0.36,I 2 = 8.62, 95% CI = 0.00–45.27). Additionally, the significant association was also found between the methylation of the RASSF1A gene and the subgroups. Conclusions This is the first meta-analysis that has provided scientific evidence that the methylation of RASSF1A is the potential diagnosis, prognosis, and early screening biomarker for nasopharyngeal carcinoma.

Epigenetic Regulation of the Tumour Suppressor RASSF1A in Bone Cancer Cells: DNA Methylation Study

Objective: Osteosarcoma is a bone cancer that affects children and adolescents. The RASSF1A is a tumor suppressor capable of mediating the regulation of cell cycle arrest, migration, including apoptosis. It is the most continually silenced gene that contributes to human cancer. Furthermore, RASSF1A functions as a scaffold protein that can regulate microtubules network and bind apoptotic kinases MST1 and MST2 via the Sav-RASSF-Hippo domain. Epigenetic inactivation of genes by DNA methylation is a key factor regulating gene expression and genomic stability. Our aim was to study the RASSF1A gene promoter methylation in three osteosarcomas (U2OS, Saos-2, and MG-63), two Ewing Sarcoma (A-673 and SK-ES-1), and one-fibrosarcoma (HT-1080) cell lines. Materials and Methods: Three osteosarcomas (U2OS, Saos-2, and MG-63), two Ewing Sarcoma (A-673 and SK-ES-1), and one-fibrosarcoma (HT-1080) cell lines were used to study RASSF1A gene promoter methylation, using bisulphite conversion of DNA, followed by methylation-specific polymerase chain reaction (PCR) Results: The RASSFIA’s gene promoter methylation was established as a frequent event. Hypermethylation of RASSF1A promoter, was detected in five out of six studied cell lines. Conclusions: These results demonstrated that altering the Sav-RASSF1-Hippo may be accomplished through hypermethylation of RASSF1A and may play an essential role in Ewing’s sarcoma and Osteosarcoma. The methylation pattern of Sav-RASSF1-Hippo tumor suppressor pathway in human bone cancer along with RASSF1A expression with its effector proteins merits further investigation. This may reveal how the RASSFIA has a physiological signal transduction, including how the process of its deregulation can contribute to transformation of the cell, eventually leading to the incorporation of novel therapeutic options with improved prognosis for bone cancer.

Extracellular Superoxide Dismutase (EC-SOD) Regulates Gene Methylation and Cardiac Fibrosis During Chronic Hypoxic Stress

BackgroundChronic hypoxic stress induces epigenetic modifications in cardiac fibroblasts, such as inactivation of tumor suppressor genes (RASSF1A), and activation of kinases (ERK1/2). The effects of the antioxidant enzyme, extracellular superoxide dismutase (EC-SOD), on these epigenetic changes has not been fully explored.ObjectivesTo define the effect of EC-SOD overexpression on cardiac fibrosis induced by chronic hypoxia.MethodsWild type C57B6 male mice (WT) and transgenic males with an extra copy of human hEC-SOD (TG) were housed in hypoxia (10% O2) for 21 days. Right ventricular tissue was studied for cardiac fibrosis markers using RT-PCR and Western Blot analyses. Downstream effects were studied, for both RASSF-1 expression and methylation and its relation to ERK1/2, using in-vivo & in-vitro modelsResultsThere were significant increases in markers of cardiac fibrosis : Collagen 1, Alpha Smooth Muscle Actin (ASMA) and SNAIL, in the WT hypoxic animals as compared to the TG hypoxic group (p< 0.05). Expression of DNA methylation enzymes (DNMT 1,2) was significantly increased in the WT hypoxic mice as compared to the hypoxic TG mice (p<0.001). RASSF1A expression was significantly lower and ERK1/2 was significantly higher in hypoxia WT compared to the hypoxic TG group (p<0.05). Use of SiRNA to block RASSF1A gene expression in murine cardiac fibroblast tissue culture led to increased fibroblast proliferation (p<0.05). Methylation of RASSF1A promoter region showed a significant reduction in the TG hypoxic group compared to the WT hypoxic group (0.59 vs 0.75 respectively).ConclusionsEC-SOD significantly attenuates RASSF1A gene methylation, and plays a pivotal role cardiac fibrosis induced by hypoxia.

Jianpi-Huayu Formula Inhibits Development of Hepatocellular Carcinoma by Regulating Expression of miR-602, Which Targets the RASSF1A Gene

The traditional Chinese medicine formula Jianpi-Huayu (JPHY) has been reported to be effective in the treatment of hepatocellular carcinoma (HCC). However, its underlying mechanism remains unclear. In this article, we employed an orthotopic transplantation model in nude mice to explore whether JPHY could inhibit the development of HCC by regulating miR-602, which targets the Ras association domain-containing protein 1A (RASSF1A) pathway. HCC SMMC-7721 cells were treated with JPHY to test whether the RASSF1A gene as mediated by miR-602 affected the proliferation and apoptosis of tumor cells. We subsequently detected miR-602, RASSF1A, and tumor cell apoptosis–related markers in cells and liver tumor tissues. We observed that mice treated with JPHY had smaller tumors and higher survival rates than untreated ones. Similarly, JPHY-treated SMMC-7721 cells exhibited alterations in morphology and higher cytotoxicity compared with the control group. Furthermore, we found that JPHY decreased overexpression of miR-602 and increased protein expression levels of the RASS1A gene, which in turn altered protein expression levels of tumor cell apoptosis–related genes in the cells and liver tumor tissues of drug-treated mice. These results indicated that JPHY could potentially be used to treat HCC by targeting miR-602, which targets the RASSF1A gene, which in turn plays a major role in HCC pathogenesis.