RT Journal Article
SR Electronic
T1 Isolation of a Prostate Carcinoma Cell Proliferation-inhibiting Factor from Human Seminal Plasma and Its Similarity to Transforming Growth Factor β]fr1
JF Cancer Research
JO Cancer Res
FD American Association for Cancer Research
SP 5821
OP 5825
VO 52
IS 20
A1 Lokeshwar, Balakrishna L.
A1 Block, Norman L.
YR 1992
UL http://cancerres.aacrjournals.org/content/52/20/5821.abstract
AB Human seminal plasma (SP) has been known to contain both growth-inhibitory and -stimulatory factors. We attempted to identify a factor that inhibited DNA synthesis in some metastatic prostate cancer cell lines. The SP factor was sensitive to digestion by trypsin, but its activity increased after boiling or dialysis against 1 m acetic acid, by 3- to 4-fold. The SP factor was partially purified using a cation-exchange resin. Apparent molecular mass determination by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed it to be a Mr 25,000 protein, and Mr 13,000 after reduction. This protein strongly inhibited DNA synthesis in two metastatic androgen-independent human prostatic carcinoma cell lines (PC3 and DU145) and the Dunning R3327G rat prostatic adenocarcinoma. It was ineffective on androgen-dependent LNCaP cells. The proliferation-inhibiting activity of this SP protein was specifically and completely abolished by a neutralizing anti-transforming growth factor β (TGF-β) antiserum. Furthermore, immunoblot analysis using the anti-TGF-β antiserum showed the similarity of this protein to TGF-β. The maximum concentration of this protein in SP was 165 ± 11.7 ng/ml (mean ± SD), of which only one-fourth may be present in active form under normal conditions. Identification of a TGF-β-like protein in SP might also explain the variety of growth and immune modulation properties of human SP. ©1992 American Association for Cancer Research.