Human Genetics Lab, Jamia Millia Islamia, New Delhi-110025, India.
Transl Oncol. 2009 Dec;2(4):264-70. doi: 10.1593/tlo.09148.
Aberrant DNA methylation has been recognized in human breast carcinogenesis as a common molecular alteration associated with the loss of expression of a number of key regulatory genes. The present study was undertaken to determine whether methylation and expression of p16 and FHIT genes would correlate with the estrogen receptor (ER) and progesterone receptor (PR) status.
Methylation-specific polymerase chain reaction, messenger RNA (mRNA) expression analysis, immunohistochemistry, and Western blot analysis were performed to study the methylation of p16 and FHIT genes in 351 pairs of malignant/normal breast tissues. We examined the expression of ER and PR in those specimens by immunohistochemistry. Mutations of p16 and FHIT genes in tumors were detected by direct sequencing.
The frequency of hypermethylation was 31.9% and 36.8% in p16 and FHIT genes, respectively, and showed significant harmony in concordant hypermethylation (P < .0001). In postmenopausal patients, methylation frequency in both genes is significantly higher in poorly and moderately differentiated tumors. Loss of protein expression of p16 and FHIT in 77 and 74 tumors, respectively, is associated with their methylation status in premenopausal women.
We did not find any significant differences in tumor-related gene methylation patterns relevant to both ER and PR status of breast tumors.
异常的 DNA 甲基化已在人类乳腺癌发生中被认识到，是与许多关键调控基因表达缺失相关的一种常见分子改变。本研究旨在确定 p16 和 FHIT 基因的甲基化和表达是否与雌激素受体 (ER) 和孕激素受体 (PR) 状态相关。
采用甲基化特异性聚合酶链反应、信使 RNA (mRNA) 表达分析、免疫组织化学和 Western blot 分析方法，研究了 351 对恶性/正常乳腺组织中 p16 和 FHIT 基因的甲基化。我们通过免疫组织化学检测了这些标本中 ER 和 PR 的表达。通过直接测序检测肿瘤中 p16 和 FHIT 基因的突变。
p16 和 FHIT 基因的高甲基化频率分别为 31.9%和 36.8%，在一致的高甲基化中显示出显著的一致性（P<0.0001）。在绝经后患者中，这两个基因的甲基化频率在低分化和中分化肿瘤中显著较高。在 77 例和 74 例肿瘤中，p16 和 FHIT 的蛋白表达缺失分别与它们在绝经前妇女中的甲基化状态相关。
我们没有发现与乳腺癌肿瘤的 ER 和 PR 状态相关的肿瘤相关基因甲基化模式有任何显著差异。
