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

Abstract

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.