Liu Jun-Wei, Nagpal Jatin K, Sun Wenyue, Lee Juna, Kim Myoung Sook, Ostrow Kimberly L, Zhou Shaoyu, Jeronimo Carmen, Henrique Rui, Van Criekinge Wim, Moon Chu So, Califano Joseph A, Trink Barry, Sidransky David
Division of Head and Neck Cancer Research, Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Clin Cancer Res. 2008 Jun 15;14(12):3754-60. doi: 10.1158/1078-0432.CCR-07-4763.
Prostate cancer is a major cause of cancer death among men and the development of new biomarkers is important to augment current detection approaches.
We identified hypermethylation of the ssDNA-binding protein 2 (SSBP2) promoter as a potential DNA marker for human prostate cancer based on previous bioinformatics results and pharmacologic unmasking microarray. We then did quantitative methylation-specific PCR in primary prostate cancer tissues to confirm hypermethylation of the SSBP2 promoter, and analyzed its correlation with clinicopathologic data. We further examined SSBP2 expression in primary prostate cancer and studied its role in cell growth.
Quantitative methylation-specific PCR results showed that the SSBP2 promoter was hypermethylated in 54 of 88 (61.4%) primary prostate cancers versus 0 of 23 (0%) in benign prostatic hyperplasia using a cutoff value of 120. Furthermore, we found that expression of SSBP2 was down-regulated in primary prostate cancers and cancer cell lines. Hypermethylation of the SSBP2 promoter and its expression were closely associated with higher stages of prostate cancer. Reactivation of SSBP2 expression by the demethylating agent 5-aza-2'-deoxycytidine in prostate cancer cell lines confirmed epigenetic inactivation as one major mechanism of SSBP2 regulation. Moreover, forced expression of SSBP2 inhibited prostate cancer cell proliferation in the colony formation assay and caused cell cycle arrest.
SSBP2 inhibits prostate cancer cell proliferation and seems to represent a novel prostate cancer-specific DNA marker, especially in high stages of human prostate cancer.
前列腺癌是男性癌症死亡的主要原因之一，开发新的生物标志物对于增强当前的检测方法很重要。
基于先前的生物信息学结果和药物去掩蔽微阵列，我们将单链DNA结合蛋白2（SSBP2）启动子的高甲基化鉴定为人类前列腺癌的潜在DNA标志物。然后，我们在原发性前列腺癌组织中进行了定量甲基化特异性PCR，以确认SSBP2启动子的高甲基化，并分析其与临床病理数据的相关性。我们进一步检测了原发性前列腺癌中SSBP2的表达，并研究了其在细胞生长中的作用。
定量甲基化特异性PCR结果显示，在88例原发性前列腺癌中有54例（61.4%）的SSBP2启动子发生高甲基化，而在23例良性前列腺增生中为0例（0%），临界值为120。此外，我们发现原发性前列腺癌和癌细胞系中SSBP2的表达下调。SSBP2启动子的高甲基化及其表达与前列腺癌的更高分期密切相关。在前列腺癌细胞系中，去甲基化剂5-氮杂-2'-脱氧胞苷使SSBP2表达重新激活，证实表观遗传失活是SSBP2调控的主要机制之一。此外，在集落形成试验中，强制表达SSBP2可抑制前列腺癌细胞增殖并导致细胞周期停滞。
SSBP2抑制前列腺癌细胞增殖，似乎代表一种新的前列腺癌特异性DNA标志物，尤其是在人类前列腺癌的高分期中。
