Abnormal promoter methylation of p14(ARF), p16(INK4a)and BUB3 genes in malignant transformed cells induced by radiation

Abstract

The methylation of tumor suppressor genes is believed to be one of the most important mechanisms of oncogenesis. In order to research the malignant transformed mechanism induced by radiation, the abnormal promoter methylation of p14(ARF) , p16(INK4a) and BUB3 genes are detected in the transformed human bronchial epithelial cells (BEP2D) induced by α-particles. Abnormal promoter methylations were detected with methylation specific PCR (MSP). The level of p14 ARF gene transcription was analyzed by using RT-PCR. DNA was purified and transformed and sequenced. p14(ARF) gene was not methylated in BEP2D cells, but was methylated in the malignant transformed BERP35T-1 cells, and the level of its transcription was depressed remarkably in the latter. However p16(INK4a) gene, which shares two exons with p14 (ARF) gene, was not methylated. BUB3 gene was not methylated in BEP2D as well as BERP35T-1 cells and this was further proved by sequencing analysis. The methylation of two tumor suppressor genes (p14(ARF) and p16(INK4a)) that share two exons and controll cell cycle are not synchronous in the transformed human bronchial epithelial cells induced by α-particles, and the methylated one (p14(ARF)) is repressed in transcription. The gene of mitosis spindle check-point (BUB3) is unmethylated.