Sørensen Karina Dalsgaard, Wild Peter Johannes, Mortezavi Ashkan, Adolf Katja, Tørring Niels, Heebøll Sara, Ulhøi Benedicte Parm, Ottosen Peter, Sulser Tullio, Hermanns Thomas, Moch Holger, Borre Michael, Ørntoft Torben Falck, Dyrskjøt Lars
Molecular Diagnostics Laboratory, Department of Clinical Biochemistry, Institute of Pathology, Aarhus University Hospital, Aarhus, Denmark.
Clin Cancer Res. 2009 Feb 15;15(4):1400-10. doi: 10.1158/1078-0432.CCR-08-2268.
This study investigates SLC18A2 (vesicular monoamine transporter 2) expression in prostate adenocarcinoma and examines its potential as a predictive marker for prostate cancer patient outcome after radical prostatectomy.
Expression and single nucleotide polymorphism microarray analyses identified SLC18A2 as both down-regulated and subject to common loss-of-heterozygosity in prostate cancer. Down-regulated SLC18A2 expression was validated on tissue microarrays containing benign and malignant prostate specimens from an independent patient group (n=738). Furthermore, SLC18A2 immunoreactivity in radical prostatectomy tumor specimens (n=506) was correlated to clinicopathologic characteristics and recurrence-free survival. The possibility of SLC18A2 silencing by aberrant DNA methylation in prostate cancer cells was investigated by bisulfite sequencing.
Tissue microarray analysis revealed markedly lower cytoplasmic SLC18A2 staining in cancer compared with nonmalignant prostate tissue samples, confirming RNA expression profiling results. Furthermore, multivariate analysis identified cytoplasmic SLC18A2 immunoreactivity as a novel predictor of biochemical recurrence following prostatectomy (hazard ratio, 0.485; 95% confidence interval, 0.333-0.709; P<0.001) independent of prostate-specific antigen, Gleason score, tumor stage, and surgical margin status. SLC18A2 showed loss-of-heterozygosity in 23% of the tumors and was densely hypermethylated in 15 of 17 (88%) prostate cancer samples plus 6 of 6 prostate cancer cell lines. In contrast, SLC18A2 was unmethylated in 4 of 4 adjacent nonmalignant prostate and 3 of 5 benign prostatic hyperplasia tissue samples, whereas 2 of 5 benign prostatic hyperplasia samples had monoallelic hypermethylation. Methylation and histone deacetylase inhibitory agents rescued SLC18A2 expression in three prostate cancer cell lines.
SLC18A2 silencing by DNA hypermethylation and/or allelic loss is a frequent event in prostate cancer and a novel independent predictor of biochemical recurrence after prostatectomy.
本研究调查SLC18A2（囊泡单胺转运体2）在前列腺腺癌中的表达，并检验其作为前列腺癌患者根治性前列腺切除术后预后预测标志物的潜力。
表达和单核苷酸多态性微阵列分析确定SLC18A2在前列腺癌中既下调又存在常见的杂合性缺失。在包含来自一个独立患者组（n = 738）的良性和恶性前列腺标本的组织微阵列上验证了SLC18A2表达下调。此外，在根治性前列腺切除肿瘤标本（n = 506）中，SLC18A2免疫反应性与临床病理特征和无复发生存相关。通过亚硫酸氢盐测序研究了前列腺癌细胞中异常DNA甲基化导致SLC18A2沉默的可能性。
组织微阵列分析显示，与非恶性前列腺组织样本相比，癌组织中细胞质SLC18A2染色明显较低，证实了RNA表达谱分析结果。此外，多变量分析确定细胞质SLC18A2免疫反应性是前列腺切除术后生化复发的一个新的预测指标（风险比，0.485；95%置信区间，0.333 - 0.709；P < 0.001），独立于前列腺特异性抗原、Gleason评分、肿瘤分期和手术切缘状态。23%的肿瘤中SLC18A2显示杂合性缺失，在17个前列腺癌样本中的15个（88%）以及6个前列腺癌细胞系中的6个中，SLC18A2高度甲基化。相比之下，4个相邻非恶性前列腺组织样本中的4个以及5个良性前列腺增生组织样本中的3个中，SLC18A2未甲基化，而5个良性前列腺增生样本中的2个有单等位基因高甲基化。甲基化和组蛋白去乙酰化酶抑制剂挽救了三种前列腺癌细胞系中SLC18A2的表达。
DNA高甲基化和/或等位基因缺失导致SLC
