Downregulated mRNA expression of ASPP and the hypermethylation of the 5'-untranslated region in cancer cell lines retaining wild-type p53.

The p53 protein is one of the best-known tumour suppressors. Recently discovered ASPP1 and ASPP2 are specific activators of p53. To understand, if apoptosis-stimulating protein of p53 (ASPP) inactivation offers a selective advantage to tumors that have wild-type p53, we measured the mRNA expression of ASPP1 and ASPP2 in tumor cell lines retaining wide-type p53. In addition, the CpG island methylation status of ASPP1 gene and ASPP2 gene in the 5'-untranslated region was also investigated in order to understand the possible cause of abnormal expression of ASPP1 and ASPP2 in the tumor cell lines retaining wide-type p53. The data showed that mRNA expression of ASPP1 and ASPP2 is downregulated and CpG island tested is hypermethylated. These results indicated that ASPP CpG island aberrant methylation could be one molecular and genetic alteration in wild-type p53 tumours.