Purpose: The WT p53 gene appears to have a broad role in suppressing prostatic tumorigenesis. We identified the mechanisms responsible for the effect of p53 on prostate specific antigen (PSA) expression by prostate cancer cell lines in vitro and investigated the role of a putative p53 response element in the PSA promoter region in prostate cancer cells.
Materials and methods: LNCaP cells were used to determine the effect of doxorubicin on p53 and PSA expression. The putative p53 response element in the human PSA promoter was identified by transient gene expression with site direct mutagenesis assays using a PSA reporter vector. Quantitative PSA secretions were assessed using enzyme-linked immunosorbent assays.
Results: Enzyme-linked immunosorbent and immunoblot assays indicated that doxorubicin treatment increased p53 expression but inhibited PSA levels in LNCaP cells. Transient gene expression assays showed that human PSA promoter activity was blocked by doxorubicin treatment. Mutation of the p53 response element GGGCATGTCT to GGGAGGATCT abolished the blocking effects of doxorubicin on PSA gene promoter activity.
Conclusions: Results demonstrate that p53 regulates PSA gene expression through a putative p53 response element in the PSA promoter within human prostate cancer cells.