The Expression Of Prostate Stem Cell Antigen In Different Prostatic Tissues Detected By In Situ Hybridization

[Background] Prostate stem cell antigen (PSCA) is a recently-found tumor antigen related to prostate cancer with 30% homology to stem cell antigen-2 (SCA-2), a member of the Thy-1/Ly-6 family cell surface antigens. The biological function of PSCA is still unknown. PSCA is predominantly prostate-specific in normal male tissues and the expression of PSCA mRNA localizes in normal prostate to the basal cell epithelium. Some studies have demonstrated that PSCA is overexpressed in greater than 80ï¼… of prostate cancer tissues and there are no differences between androgen-dependent and androgen-independent prostate tumors. The PSCA mRNA in lesions of bone metastasis is 100% overexpressed and the expression level is higher than that of primary tumor. As we know, the systemic control study of the expression differences of PSCA among different prostatic tissuses has not been done yet. [Objective] The thesis was conducted to assess the differences of PSCA mRNA expression among nomal prostate, benign prostatic hyperpalsia and prostate cancer by in situ nucleic acid hybridization technique. The goal is to explore the meaning of PSCA expression in prostate tissue and to provide a useful tumor-specific antigen for diagnosis and immunotherapy of prostate cancer.[Methods] According to the full-length PSCA mRNA offered by Reiter, the first researcher of PSCA, we layout two primers to be used to amplify a 339bp fragment of open reading frame sequence in total RNA isolated from PC3 cells. In vitro transcription method was used to produce the digoxigenin-labeled antisence cRNA probe. The expression of PSCA were analyzed by in situ nucleic acid hybridization in a group of prostate specimens in which 9 normal prostate, 20 BPH and 26 prostate cancer samples were included. [Results] The positive rate of PSCA mRNA expression in normal prostate, BPH and prostate cancer is 66.7%, 70.0% and 84.6%, and the strong positive rate of which is 0%, 10% and 57.7% respectively. The expression in normal prostate and the great majority of BPH are located to the basal cell epithelium. Two cases of BPH specimens are overexpressed both in basal cells and in secretory cells. As to prostate cancer, PSCA mRNA is predominantly expressed in tumor cells. No stroma and muscle were stained in prostate cancer. The PSCA mRNA expression level has no statistical difference between normal prostate and BPH tissues. As compared to normal prostate and BPH tissues, the PSCA mRNA expression level of prostate cancer has significant statistical differences. Both clinic stage and cell grade of prostate cancer are not statistically correlation to the expression level. [Conclusions] PSCA is a predominantly prostate-specific antigen. Its expression located to the basal cell epithelium. BPH have no influence on the expression level of PSCA. PSCA is characteristic overexpressed in prostate cancer, and all sorts of prostate cancer expressed nearly at the same level. The results imply that PSCA may be an attrative target of prostate cancer diagnosis and immunotherapy.