Rehman Ishtiaq, Cross Simon S, Catto James W F, Leiblich Aaron, Mukherjee Abir, Azzouzi Abdel-Rahmene, Leung Hing Y, Hamdy Freddie C
Academic Urology Unit, Division of Clinical Sciences South, University of Sheffield, United Kingdom, and Service d'Urologie, Groupe Hospitalier Pitié-Salpétrière, Paris, France.
Prostate. 2005 Dec 1;65(4):322-30. doi: 10.1002/pros.20302.
S100A6 and S100A2 are members of the S100 family of calcium binding proteins, which are down regulated in prostate cancer, however the molecular mechanism(s) underlying their loss of expression is unknown.
The promoter and exon 1 region of the S100A6 and S100A2 genes was sequenced in bisulfite modified DNA from non-malignant, benign prostatic hyperplasia (BPH), malignant and metastatic prostate tissues and in cell lines. Immunohistochemistry was performed to correlate S100A2 expression with methylation status.
S100A6 methylation was absent or occurred at isolated sites in 14/14 cases of non-malignant epithelium and 5/5 cases of BPH tissues, whereas methylation was seen in 14/27 (52%) cases of prostatic cancer (P<0.0001), 2/2 cases of metastatic cancer and in the CWR22 prostatic cancer xenograft. Critical CpG sites within the S100A2 promoter were methylated in LNCaP, LNCaP-LN3, and CWR22 cells but not in Du145, PC3 or BPH45 cells. In tissues, S100A2 methylation was seen in 32/34 (94%) cases of adenocarcinoma and 5/5 cases of metastatic cancer. However, S100A2 methylation was also seen in 9/12 (75%) cases of non-malignant tissues and in 5/5 cases of BPH. Immunostaining, showed absent S100A2 expression all 41 cases of prostatic cancer, whereas staining was seen in the basal cells of non-malignant epithelium.
Loss of S100A6 and S100A2 proteins is frequent in human prostatic cancer. A major mechanism underlying the loss of S100A6 expression appears to involve promoter hyper-methylation. However, mechanisms other than methylation of the known promoter are involved in silencing S100A2 in the prostate.
S100A6和S100A2是钙结合蛋白S100家族的成员，在前列腺癌中表达下调，但其表达缺失的分子机制尚不清楚。
对来自非恶性、良性前列腺增生（BPH）、恶性和转移性前列腺组织以及细胞系的亚硫酸氢盐修饰DNA中的S100A6和S100A2基因的启动子和外显子1区域进行测序。进行免疫组织化学以将S100A2表达与甲基化状态相关联。
在14/14例非恶性上皮和5/5例BPH组织中，S100A6甲基化不存在或发生在孤立位点，而在14/27（52%）例前列腺癌（P<0.0001）、2/2例转移性癌以及CWR22前列腺癌异种移植中可见甲基化。S100A2启动子内的关键CpG位点在LNCaP、LNCaP-LN3和CWR22细胞中甲基化，但在Du145、PC3或BPH45细胞中未甲基化。在组织中，32/34（94%）例腺癌和5/5例转移性癌中可见S100A2甲基化。然而，9/12（75%）例非恶性组织和5/5例BPH中也可见S100A2甲基化。免疫染色显示，41例前列腺癌中S100A2表达均缺失，而非恶性上皮的基底细胞中可见染色。
S100A6和S100A2蛋白缺失在人类前列腺癌中很常见。S100A6表达缺失的主要机制似乎涉及启动子高甲基化。然而，前列腺中S100A2沉默涉及已知启动子甲基化以外的机制。
