Expression, Mutation, And Methylation Of P33～(ING1b) In Sporadic Colorectal Carcinoma

Purpose:ING1 has been identified as a novel tumor suppressor gene, and proved to be involved in the modulation of cell cycle. Its expression can inhibit cell growth, control celluar aging, and induce cell apotosis. It has more than 3 different splices at transcription, and becomes three subtypes (p33^ING1b, p47^ING1a 和 p24^ING1c) at least. P33^ING1b is a 'molecular partner' of wild type p53. Decreased expression of p33^ING1b mRNA has been found in some human tumors, but mutation of p33^ING1b was rarely found. It suggests that p33^ING1b exploits the effect on the genesis and progression of cancer by decreased expression, not by mutation. Decreased expression of EphA7, CDX2, E2F are caused by their promoter methylaion in colorectal cancer. There are seldom reports about p33^ING1b in colorectal cancer, and no report about its methylaion by now. Our study was to explore the effect and siginificance of p33^ING1b on the genesis and progression of sporadic colorectal cancer by detecting mRNA expression, mutation and promoter methylaion of p33^ING1b. Methods:mRNA expression, mutation and promoter methylaion of p33^ING1b in 46 specimens of sporadic colorectal cancerous tissues and matched normal tissues were detected by semi-quantitative RT-PCR, PCR-SSCP and MSP, respectively. Results:(1) All 46 samples of tumor tissues and matched normal mucosae tissues express p33^ING1b mRNA. The average ratios of light density of P33^ING1b mRNA in the cancerous and normal tissues were 0.52 and 1.28, significant difference between...