Department of Gastroenterology, Hepatology, and Infectious Diseases, Otto-von-Guericke University, 39120 Magdeburg, Germany.
BMC Cancer. 2010 Jun 22;10:317. doi: 10.1186/1471-2407-10-317.
The product of CDKN2A, p16 is an essential regulator of the cell cycle controlling the entry into the S-phase. Herein, we evaluated CDKN2A promoter methylation and p16 protein expression for the differentiation of hepatocellular carcinoma (HCC) from other liver tumors.
Tumor and corresponding non-tumor liver tissue samples were obtained from 85 patients with liver tumors. CDKN2A promoter methylation was studied using MethyLight technique and methylation-specific PCR (MSP). In the MethyLight analysis, samples with > or = 4% of PMR (percentage of methylated reference) were regarded as hypermethylated. p16 expression was evaluated by immunohistochemistry in tissue sections (n = 148) obtained from 81 patients using an immunoreactivity score (IRS) ranging from 0 (no expression) to 6 (strong expression).
Hypermethylation of the CDKN2A promoter was found in 23 HCCs (69.7%; mean PMR = 42.34 +/- 27.8%), six (20.7%; mean PMR = 31.85 +/- 18%) liver metastases and in the extralesional tissue of only one patient. Using MSP, 32% of the non-tumor (n = 85), 70% of the HCCs, 40% of the CCCs and 24% of the liver metastases were hypermethylated. Correspondingly, nuclear p16 expression was found immunohistochemically in five (10.9%, mean IRS = 0.5) HCCs, 23 (92%; mean IRS = 4.9) metastases and only occasionally in hepatocytes of non-lesional liver tissues (mean IRS = 1.2). The difference of CDKN2A-methylation and p16 protein expression between HCCs and liver metastases was statistically significant (p < 0.01, respectively).
Promoter methylation of CDKN2A gene and lack of p16 expression characterize patients with HCC.
CDKN2A 基因的产物 p16 是细胞周期的重要调节因子，控制细胞进入 S 期。在此，我们评估了 CDKN2A 启动子甲基化和 p16 蛋白表达在肝细胞癌 (HCC) 与其他肝脏肿瘤的鉴别诊断中的作用。
从 85 例肝脏肿瘤患者中获取肿瘤和相应的非肿瘤肝组织样本。采用 MethyLight 技术和甲基化特异性 PCR（MSP）检测 CDKN2A 启动子甲基化。在 MethyLight 分析中，PMR（甲基化参考百分比）≥4%的样本被视为高甲基化。采用免疫组织化学方法在 81 例患者的组织切片（n=148）中检测 p16 表达，免疫反应性评分（IRS）范围为 0（无表达）至 6（强表达）。
23 例 HCC（69.7%；平均 PMR=42.34±27.8%）、6 例（20.7%；平均 PMR=31.85±18%）肝转移和 1 例非肿瘤肝组织中存在 CDKN2A 启动子高甲基化。MSP 检测结果显示，85 例非肿瘤组织（n=85）、70%的 HCC、40%的 CCC 和 24%的肝转移存在高甲基化。相应地，免疫组化检测到 5 例（10.9%，平均 IRS=0.5）HCC、23 例（92%，平均 IRS=4.9）转移瘤中存在核 p16 表达，而非病变肝组织的肝细胞中偶尔出现（平均 IRS=1.2）。HCC 和肝转移中 CDKN2A 甲基化和 p16 蛋白表达的差异具有统计学意义（分别为 p<0.01）。
CDKN2A 基因启动子甲基化和 p16 蛋白缺失是 HCC 的特征。
