Methylation and silencing of the retinoic acid receptor-β2 gene in breast cancer
Methylation and silencing of the retinoic acid receptor-β2 gene in breast cancer
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DOI：
10.1093/jnci/92.10.826
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发表时间：
2000-05-17
期刊：
影响因子：
--
通讯作者：
Marth, C
中科院分区：
文献类型：
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作者：
Widschwendter, M;Berger, J;Marth, C
背景：越来越多的证据支持视黄酸受体β 2 （rar - β 2）基因是肿瘤抑制基因的假设，类维甲酸的化学预防作用是：由于rar - β 2的诱导，在许多恶性肿瘤中rar - β 2的表达减少，我们研究了rar - β 2的甲基化是否可能是这种沉默的原因。方法：用逆转录聚合酶链反应（RT-PCR）分析了8株乳腺癌细胞系中rar - β 2的表达，这些细胞系分别用去甲基化剂5-aza-2'-脱氧胞苷和全反式维甲酸（ATRA）处理或不处理。亚硫酸氢钠基因组测序用于确定其中三个细胞系的rar - β 2基因中5-甲基胞嘧啶的位置。在16例乳腺癌活检标本和非肿瘤性乳腺组织中，采用甲基化特异性PCR检测rar - β 2的甲基化状态，并在其中13例标本中采用RT-PCR分析检测rar - β 2的表达。结果：细胞株SK-BR-3、T-47D、ZR-75-1和MCF7仅在去甲基化和ATRA处理后才表现出rar - β 2的表达，在细胞株ZR-75-1和SK-BR-3中，rar - β 2转录物中表达的第一个外显子被甲基化，6例乳腺癌标本在该基因的同一区域出现甲基化。在任何III级病变中均未发现rar - β 2表达。在所有II级病变中发现甲基化与基因表达呈负相关，来自非肿瘤性乳腺组织的par - β 2基因未甲基化并表达。结论：rar - β 2基因的甲基化可能是乳腺癌发生的第一步；用去甲基化药物治疗癌症患者后加维甲酸可能提供一种新的治疗方式。
Background: A growing body of evidence:supports the hypotheses that the retinoic acid: receptor beta 2 (RAR-beta 2) gene is a tumor suppressor gene and that the chemopreventive effects of retinoids are:due to induction of RAR-beta 2, RAR-beta 2 expression is reduced in many malignant tumors, and we examined whether methylation of RAR-beta 2 could be responsible for this silencing. Methods: RAR-beta 2 expression was studied by reverse transcription-polymerase chain reaction (RT-PCR) analysis in eight breast Cancer cell lines that were either treated-with the demethylating agent 5-aza-2'-deoxycytidine and subsequently with all-trans-retinoic acid (ATRA) or left untreated. Sodium bisulfite genomic sequencing was used to determine the locations 5-methylcytosines in the RAR-beta 2 genes of three of these cell lines. In 16 breast cancer biopsy specimens and non-neoplastic breast tissue, methylation-specific PCR was used to determine the methylation status of RAR-beta 2, and, in 13 of the specimens, RT-PCR analysis was used to detect RAR-beta 2 expression. Results: Cell lines SK-BR-3, T-47D, ZR-75-1, and MCF7 exhibited: expression of RAR-beta 2 only after demethylation and treatment with ATRA, The first exon expressed in the RAR-beta 2 transcript was methylated in cell lines ZR-75-1 and SK-BR-3, Six breast cancer specimens showed methylation in,the same region of the gene. No expression of RAR-beta 2 was found in any grade III lesion. An inverse association between methylation and gene expression was found in all grade II lesions, The PAR-beta 2 gene from nonneoplastic breast tissue was unmethylated and expressed. Conclusions: Methylation of the RAR-beta 2 gene may be an initial step in breast carcinogenesis; treatment of cancer patients with demethylating agents followed by retinoic acid may offer a new therapeutic modality.