前列腺跨膜上皮抗原在前列腺癌组织中的表达及与PSA的关系

Expression of six-transmembrane epithelial antigen of the prostate in prostate cancer and its correlation with prostate specific antigen

目的探讨前列腺癌组织中前列腺跨膜上皮抗原（STEAP）表达及与前列腺特异性抗原（PSA）的关系。方法采用免疫组织化学染色法检测65例前列腺癌（其中T19例、T214例、T317例、T425例，高分化癌37例、中分化癌12例、低分化癌16例）组织标本中STEAP的表达，引入阳性灰度值概念判定染色强度；分析STEAP表达水平与肿瘤分期、分级、血清PSA及游离PSA／总PSA（f／tPSA）比值的关系。结果65例患者血清PSA值为（27．65±8．34）ng／ml，f／tPSA为0．15±0．04。STEAP阳性表达63例，其中T17例、T214例、T317例、T425例，高分化癌37例、中分化癌11例、低分化癌15例。T1、T2、T3、T4前列腺癌组织中STEAP表达平均阳性灰度值（Gs）分别为26．8％、45．6％、62．3％、76．5％，高、中、低分化癌组织中STEAP表达平均Gs分别为71．2％、52．8％、34．4％。STEAP表达与肿瘤分期呈正相关（r=0．67，P〈O．01）；随着Gleason评分的增高，STEAP表达逐渐降低（P〈O．01）；STEAP表达与患者血清PSA无明显相关性（r=0．21，P〉0．05），而与f／tPSA比值呈负相关（r=-0．83，P〈0．01）。结论STEAP可作为判断前列腺癌浸润深度、分化程度的指标之一。

Objective To investigate the expression of six-transmembrane epithelial antigen of the prostate （STEAP） in prostate cancer and its relationship with prostate specific antigen （PSA）. Methods A retrospective analysis was performed of 65 consecutive patients verified for prostate cancer by prostate biopsy or post-operational pathological examination. The clinical stage was classified according to TNM system and the pathological grade was classified according to Gleason score. STEAP expression in 65 prostate cancer samples （ T1 9, T2 14, T3 17, T4 25;high differentiation 37, moderate differentiation 12 and low differentiation 16） was studied by using STEAP monoclonal antibody （Santa Cruz Biotech, USA） and SP immunohistochemical staining. Positive staining gray values were introduced to describe the intensity of STEAP expression. STEAP expression level was analyzed with respect to stage, grade, serum total PSA and free/total PSA （f/t PSA） ratio respectively. Results The serum total PSA concentration and f/t PSA ratio in all cases was （27. 65±8. 34） ng/ml and 0.15±0.04 respectively. STEAP was positively stained in 63 patients （T1 7, T2 14, Ta 17, T4 25; high differentiation 37, moderate differentiation 11 and low differentiation 15）. The mean STEAP- positive staining gray values in stage T1 , T2, T3 and T4 of prostate cancer were 26. 8%, 45. 6%, 62.3% and 76.5%, respectively and in high, moderate and low differentiation group were 71.2%, 52.8%, and 34.4% respectively. The positive staining gray values of STEAP expression was posi tively correlated to the clinical stage of cancer and negatively correlated to the Gleason score and the ratio of f/t PSA （P〈0.01, respectively）. There was no significant relationship between STEAP ex pression and serum total PSA concentration （P〉0.05）. Conclusion STEAP expression may act as one of new markers to the invasion degree and pathological grade of prostate cancer.