Our research intends to obtain extra-cellular proteinogram of cell lines representing different advancement stages of prostate cancer and to test whether screened differential expression proteins can be secreted and used as serum biomarkers for prostate cancer. By examining differential expression spots in two extra-cellular protein 2D-PAGE gels and mass spectrum, candidate molecules were obtained. The expressions of these candidate molecules in eight cell lines and response to androgen stimulus in LNCaP were analyzed by RT-PCR. By constructing eukaryotic expression vectors and western-blotting with anti tags antibodies, the candidate molecules were tested to understand whether they can be expressed in transfected 293T cell culture fluid. Two overexpressed molecules-triosephosphate isomerase 1 (TPI1) and syndecan bind-ing protein, syntenin (ST1)-in extra-cellular proteinogram of C4-2 were screened out; both of them are secretary proteins. On transcriptional level, both proteins were up-regulated with the malignancy of prostate cancer cell lines and ST1 was dose-dependently inhibited by androgen. Considering cellular level results, both TPI1 and ST1 have their potential as serum biomarkers for indicating the developmental stage of prostate cancer.