Expression of semenogelins I and II and its prognostic significance in human prostate cancer.

BACKGROUND: Little is known about the role of semenogelins, seminal plasma proteins that play critical roles in semen clotting and subsequent liquefaction in the presence of zinc and prostate-specific antigen, in human malignancies.
METHODS: We investigated the expression of semenogelins in four human prostate cancer lines by RT-PCR and Western blotting as well as in 70 radical prostatectomy specimens by immunohistochemistry. Effects of semenogelin overexpression on prostate cancer cell proliferation were also assessed.
RESULTS: mRNA/protein signals for semenogelins I (SgI) and II (SgII) were detected only in androgen-sensitive LNCaP cells cultured with zinc. Transfection of SgI/SgII increased/decreased cell growth of androgen receptor (AR)-positive/semenogelin-negative CWR22Rv1 in the presence of zinc, whereas it showed marginal effects in AR-negative/semenogelin-negative PC-3 and DU145. Immunohistochemical studies showed that SgI and SgII stain positively in 55 (79%) and 31 (44%) cancer tissues, respectively, which was significantly higher than in corresponding benign tissues [SgI-positive in 13 (19%) cases (P < 0.0001) and SgII-positive in 15 (21%) cases (P = 0.0066)]. Among the histopathological parameters available for our patient cohort, there was an inverse association only between Gleason score (GS) and SgII expression (GS ≤ 7 vs. GS ≥ 8: P = 0.0150; GS7 vs. GS ≥ 8: P = 0.0111). Kaplan-Meier and log-rank tests further revealed that patients with SgI-positive/SgII-negative tumor have the highest risk for biochemical recurrence (P = 0.0242).
CONCLUSIONS: These results suggest the involvement of semenogelins in prostate cancer and their prognostic values in predicting cancer progression after radical prostatectomy. Additional functional analyses of semenogelins are necessary to determine their biological significance in prostate cancer.