Aberrant CpG island methylation of the p16INK4a and estrogen receptor genes in rat lung tumors induced by particulate carcinogens
Aberrant CpG island methylation of the p16INK4a and estrogen receptor genes in rat lung tumors induced by particulate carcinogens
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DOI：
10.1093/carcin/23.2.335
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发表时间：
2002-02-01
期刊：
影响因子：
4.7
通讯作者：
Palmisano, WA
中科院分区：
文献类型：
--
作者：
Belinsky, SA;Snow, SS;Palmisano, WA
我们实验室最近的研究表明，p16（INKa）基因在遗传毒性致癌物诱导的肺肿瘤中经常甲基化，并且雌激素受体a （ER）基因甲基化的频率随致癌物暴露而变化。本研究的目的是确定这两个基因在微粒致癌物炭黑（CB）、柴油废气（DE）或金属铍诱发的肺肿瘤中的作用。在59%的DE和46%的CB肿瘤中分别观察到p16甲基化。相比之下，只有15%的DE或CB肿瘤中ER基因失活。p16和ER基因甲基化在铍诱导的肺肿瘤中非常常见（分别为80%和50%）；在40%的肿瘤中，这两个基因都甲基化了。亚硫酸氢盐测序显示ER基因外显子1的密集甲基化。通过RT-PCR表达研究证实了甲基化对基因转录的抑制作用，其中p16基因在甲基化肿瘤中的表达比未甲基化肿瘤低30-60倍。甲基化肿瘤中的残留表达与基质细胞和炎症细胞的污染一致。结果表明，这些微粒致癌物诱发的肿瘤部分是通过p16和ER基因失活而产生的。此外，这些致癌暴露导致p16基因失活，支持了氧化应激和炎症在人类肺癌病因学中的可能作用。
Recent studies by our laboratory indicate that the p16(INKa) gene is frequently methylated in lung tumors induced by genotoxic carcinogens and that the frequency for methylation of the estrogen receptor a (ER) gene varies as a function of carcinogenic exposure. The purpose of the current investigation was to define the role of these two genes in lung tumors induced by the particulate carcinogens carbon black (CB), diesel exhaust (DE) or beryllium metal. Methylation of p16 was observed in 59 and 46% of DE and CB tumors, respectively. In contrast, the ER gene was inactivated in only 15% of DE or CB tumors. Methylation of the p16 and ER genes was very common (80 and 50%, respectively) in beryllium-induced lung tumors; both genes were methylated in 40% of the tumors. Bisulfite sequencing revealed dense methylation throughout exon 1 of the ER gene. The inhibitory effect of methylation on gene transcription was confirmed through RT-PCR expression studies in which p16 gene expression was 30-60-fold lower in methylated than unmethylated tumors. Residual expression in methylated tumors was consistent with contamination by stromal and inflammatory cells. Results indicate that tumors induced by these particulate carcinogens arise, in part, through inactivation of the p16 and ER genes. Furthermore, the inactivation of the p16 gene by these carcinogenic exposures supports a possible role for oxidative stress and inflammation in the etiology of human lung cancer.