Immunoreactivity, ultrastructural localization, and transcript expression of prostate-specific antigen in human neuroblastoma cell lines

Prostate-specific antigen (PSA) is considered a highly specific biochemical marker of the human prostate gland, and it currently is used for prostate cancer diagnosis and monitoring. Recently, PSA production and secretion wer e found in nondiseased and diseased cells, tissues, and fluids from women. In this study, we characterized the presence of PSA in two human neuroblast oma cell lines with biochemical, ultrastructural, and molecular approaches. Using reverse transcription-PCR, we identified PSA mRNA, and Western blott ing revealed a substantial amount of complexed form of PSA protein, which i s localized mainly in free ribosomes. Although the role of PSA in human neu roblastoma cell lines is still unknown, our study supports the hypothesis t hat this serine protease may be involved in controlling the growth of human brain tumor cells, adding more support to the notion that PSA is a widespr ead kallikrein-like protease with biological functions much more complex th an recently thought.