Gross Mitchell, Top Irina, Laux Isett, Katz Jonathan, Curran John, Tindell Charles, Agus David
Louis Warschaw Prostate Cancer Center, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA.
Clin Cancer Res. 2007 Apr 1;13(7):1979-86. doi: 10.1158/1078-0432.CCR-06-1156.
A better understanding of secreted proteins may lead to the discovery of new biomarkers, which, along with prostate-specific antigen (PSA), may be useful in the diagnosis and treatment of prostate cancer patients.
Conditioned medium was collected from LNCaP cells following stimulation with methyltrienolone (R1881), 17beta-estradiol (estradiol), or interleukin-6 and analyzed for differential protein expression with surface-enhanced laser desorption/ionization-time of flight mass spectrometry. Quantitative reverse transcription-PCR, immunoblots, and ELISA were used to measure beta-2-microglobulin (B2M) message and protein levels in cells, conditioned medium, and serum.
Surface-enhanced laser desorption/ionization-time of flight revealed that many peaks were induced or repressed following stimulation with R1881 or estradiol. A peak of interest centered at 11.8 kDa was chosen for additional analysis. Immunodepletion identified the peak of interest as B2M. Reverse transcription-PCR and immunoblots confirmed that PSA and B2M were induced by R1881. However, unlike PSA, B2M was not increased on stimulation with estradiol or interleukin-6. Human B2M is identified in the serum of mice bearing human prostate cancer xenograft. B2M is expressed in human prostate cancer cell lines and tissues. Serum B2M levels are elevated in patients with metastatic, androgen-independent prostate cancer.
B2M is a secreted protein expressed in prostate cancer, which is more specific for androgen stimulation than PSA under the conditions tested. Additional studies are warranted to explore if B2M is as useful marker for prostate cancer. Identification of proteins secreted from cancer cells in preclinical models may be a useful strategy for biomarker discovery.
更好地了解分泌蛋白可能会促成新生物标志物的发现，这些标志物与前列腺特异性抗原（PSA）一起，可能有助于前列腺癌患者的诊断和治疗。
用甲基三烯醇酮（R1881）、17β-雌二醇（雌二醇）或白细胞介素-6刺激LNCaP细胞后收集条件培养基，并用表面增强激光解吸/电离飞行时间质谱分析差异蛋白表达。采用定量逆转录PCR、免疫印迹和酶联免疫吸附测定法测量细胞、条件培养基和血清中β-2-微球蛋白（B2M）的信使核糖核酸和蛋白水平。
表面增强激光解吸/电离飞行时间质谱显示，用R1881或雌二醇刺激后，许多峰被诱导或抑制。选择了一个以11.8 kDa为中心的感兴趣峰进行进一步分析。免疫去除鉴定该感兴趣峰为B2M。逆转录PCR和免疫印迹证实R1881可诱导PSA和B2M。然而，与PSA不同，用雌二醇或白细胞介素-6刺激时B2M并未增加。在携带人前列腺癌异种移植瘤的小鼠血清中鉴定出了人B2M。B2M在人前列腺癌细胞系和组织中表达。转移性雄激素非依赖性前列腺癌患者的血清B2M水平升高。
B2M是一种在前列腺癌中表达的分泌蛋白，在所测试的条件下，它对雄激素刺激比PSA更具特异性。有必要进行更多研究以探索B2M是否可作为前列腺癌的有用标志物。在临床前模型中鉴定癌细胞分泌的蛋白可能是发现生物标志物的一种有用策略。
