Targeted down-regulation of p53 gene expression by individual antisense RNA in vitro

Abstract

To investigate the effect of specific blockage of mutant p53 gene by individualized antisense RNA in vitro. Mutation status of p53 in human breast cancer cell lines was determined by immunocytochemical staining, PCR-SSCP and sequencing. Single strand antisense transcription system targeting specific p53 mutation site (mt-p53) was constructed, and corresponding antisense RNA was prepared. The hybridization of antisense RNA with its corresponding mt-p53 gene was confirmed by in-situ hybridization. Human breast cancer cells were transfected with antisense RNA by cationic liposome-mediated method. Time course of effects of antisense RNA was investigated by immunocytochemical staining and cell growth inhibiting assay. Expression of mt-p53 protein was examined by Western blot. Cell proliferation was evaluated by MTT assay and cell cycle distribution was determined by flow cytometry (FCM). Apoptosis was determined by TUNEL assay. Mutation of p53 exon 8 was found in MDA-MB-231 cells and antisense transcription system (pGEM3zf (+/-) p53exon8) was then constructed successfully. In transfected MDA-MB-231 cells, hybridization signals were observed in cytoplasm. Fourth-eight hours after transfection, the antisense RNA (ASp53exon8'RNA) had a significant retarding effect on p53 related proliferation inhibition, along with a decrease of p53 protein expression. ASp53exon8'RNA specifically blocks mt-p53 gene expression, resulting in an inhibition of MDA-MB-231 cell proliferation. Such an approach may be used as a therapeutic option against human malignancy.