ANDROGEN-SENSITIVE HUMAN PROSTATE-CANCER CELLS, LNCAP, PRODUCE BOTH N-TERMINALLY MATURE AND TRUNCATED PROSTATE-SPECIFIC ANTIGEN ISOFORMS

To characterize prostate-specific antigen (PSA) produced by cancer cel ls, different isoforms of PSA secreted by the human prostate cancer ce lls, LNCaP, were purified. LNCaP-PSA production was induced by synthet ic androgen, R1881. LNCaP-PSA was separated into four pools. The molec ular mass of LNCaP-PSA isoforms in these pools was 34 kDa under reduci ng conditions and 29 kDa under nonreducing conditions on SDS/PAGE. pI of LNCaP-PSA isoforms varied from 6.8 to 8.2. Pool A had the highest s pecific activity, 37 nmol/(minxmg). All the pools formed stable comple xes with alpha 1-antichymotrypsin and alpha 2-macroglobulin. The Fools contained 10-60% of N-terminally correctly processed LNCaP-PSA isofor ms. According to the molecular modelling, the addition or deletion of two or four N-terminal amino acids could affect the three-dimensional structure and thereby remarkably reduce the enzyme activity of LNCaP-P SA.