The effects of CYP1A1 gene polymorphism and p16 gene methylation on the risk of lung cancer in a Chinese population

Objective： To investigate the relationship between the genetic polymorphism of CYP1A1 and the genetic susceptibility to lung cancer as well as to study the effects of the methyiation in p16 gene on the risk of lung cancer in a Chinese population. Methods： A case control study was conducted among 47 cases of lung cancer and 94 controls. The genetic polymorphism of CYP1A1 was tested with method of PCR-RFLP, and a methylation-specific PCR （MSP） was performed to detect p16 methylation. Results： It showed that there was no significant difference in frequencies of the genotypes of CYP1A1 between the two groups （P 〉 0.05）. Synergistic effects were not found between smoking and CYP1AI. Methylated p16 gene was found in 44.7% （21/47） of lung cancer tissues and in 17.0% （8/47） of normal lung tissues with significant difference （P 〈 0.05）. Conclusion： The genetic polymorphism of CYP1A1 does not increase the risk of lung cancer in a Chinese population. The methylation in p16 gene may be the most common mechanism to inactivate p16 gene in lung cancer, and is not significantly associated with genotype of CYP1A1,

p16 gene methylation in colorectal cancers associated with Duke's staging

AIM: To explore the association of methylation of the CpG island in the promotor of the p16 tumor suppressor gene with the clinicopathological characteristics of the colorectal cancers. METHODS: Methylation-specific PCR (MSP) was used to detect p16 methylation of 62 sporadic colorectal cancer specimens. RESULTS: p16 methylation was detected in 42% of the tumors.Dukes'staging was associated with p16 methylation status.p16 methylation occurred more frequently in Dukes'C and D patients (75.9%) than in Dukes'A and B patients (12.1%). CONCLUSION: p16 methylation plays a role in the carcinogenesis of a subset of colorectal cancer, and it might be linked to poor prognosis.

HYPERMETHYLATION OF p14^(ARF) PROMOTER REGION AND EXPRESION OF p14^(ARF) GENE PRODUCT IN NON-SMALL CELL LUNG CANCER

Objective： This study was designed to investigate promoter methylation status and protein expression of p14^ARF gene in non-small cell lung cancer, and value the role of p14^ARF promoter methylation in carcinogenesis of non-small cell lung cancer. Methods： Promoter methylation status and protein expression of p14^ARF gene in 40 cases of non-small cell lung cancer were analyzed by methylation specific polymerase china reaction （MSP）, restriction enzyme-related polymerase chain reaction （RE-PCR） and immunohistochemistry （IHC）. Results： The positive rates of p14^ARF promoter methylation in tumor tissues and normal tissues adjacent to cancer were 17.5% （7/40） and 2.5% （1/40） respectively. There were statistically significant differences between them, P〈0.05. The results of RE-PCR were consistent with that of MSP. The expression rate of p14^ARF protein in tumor tissues was significantly lower than that in normal tissues adjacent to cancer, p〈0.01. Promoter methylation status and protein expression of p14^ARF gene in non-small cell lung cancer showed significantly an inverse correlation （r=-0.56, P〈0.01）, and both of them did not relate statistically with the clinicopathologic characteristics of patients such as histological classification, clinical stage, differentiation grade and lymph node involvement. Conclusion： Promoter methylation is a crucial mechanism of inactivation of p14^ARF gene. Promoter methylation of p14^ARF gene might he involved in carcinogenesis of non-small cell lung cancer, and is an early event in development process of non-small cell lung cancer. It might be used as a new target in gene treatments in the future.

PROMOTER HYPERMETHYLATION OF p16 GENE IN PRE- AND POST-OPERATIVE PLASMA OF PATIENTS WITH GASTRIC ADENOCARCINOMA

Objective: To detect promoter hypermethylation of p16 gene in matched pre- and post-operative plasma of patients with gastric adenocarcinoma for evaluating the effectiveness of therapeutic intervention. Methods: Tissue samples, pre- and post-operative plasma of 84 patients were collected. Plasma of 15 healthy people was collected as control. After sodium-bisulfite treatment, extracted DNA was amplified for p16 promoter by methylation-specific polymerase chain reaction (MSP). The PCR products were detected by both gel-ethidium bromide electrophoresis and high performance liquid chromatogram (HPLC). Results: Among 84 patients, p16 hypermethylation was detected in 26 (31.0%) cancer tissues and 2 (0.02%) tumor-adjacent tissues and 12 (14.3%) pre-operative plasma, while negative in plasma of healthy people. For positive plasma cases, the paired tumor tissues were confirmed to be methylated. Within available 30 pairs of matched pre- and post-operative plasma, 6 pre-operative plasma was positive, and only 1 of 6 plasma remained hypermethylated after surgery. The results detected by HPLC exactly matched those by gel-electrophoresis. Conclusion: The alteration of status of p16 hypermethylation in post-operative plasma is considered the consequences of surgical intervention. Although p16 hypermethylation has no role in pre-operative staging of gastric cancer, detecting hypermethylated p16 in plasma could be utilized in monitoring patients after surgery.

胰腺癌中p16基因甲基化改变及其蛋白表达分析

目的探讨胰腺癌与癌旁组织中p16基因启动子区异常甲基化的改变及其蛋白表达的特点,以及其与胰腺癌发生发展的关系。方法分别采用免疫组化SP法及甲基化特异PCR(MSP)检测46例人胰腺癌和癌旁组织中p16基因表达及其甲基化的水平,并结合临床资料进行分析。结果胰腺癌中p16蛋白表达率为41.3%(19/46),而癌旁组织表达率为95.7%(44/46),两者有差异显著性(P<0.01)。p16蛋白阳性的19例胰腺癌标本中均未检出基因甲基化;p16蛋白缺失的27例标本中有18例检出基因甲基化,甲基化率为39.1%。p16基因甲基化与蛋白缺失有明显关系(P<0.05)。p16基因表达及其启动子区甲基化的发生率与胰腺癌的大小,患者性别?年龄的差异无显著意义(P>0.05),但与组织分化程度?淋巴结转移?PTNM分期有显著意义(P<0.05)。结论p16基因启动子的异常甲基化可影响p16蛋白的表达,它们与胰腺癌的发生发展有关;p16甲基化和蛋白表达可能成为胰腺癌诊断及预后的候选标志物之一。

低剂量螺旋CT扫描联合血清p16基因甲基化检测在肺癌早期诊断中的应用

目的研究在无症状的肺癌高危人群中利用低剂量CT（LDCT）联合血清p16基因甲基化检测进行肺癌早期诊断的可行性。方法肺癌高危人群入组标准：男性，年龄55～75岁；吸烟指数≥400支／年，目前仍在吸烟或戒烟不超过10年。共893例受检者被随机分为两组。一组为447例（LDCT—p16组），平均年龄66岁，进行LDCT联合血清p16基因甲基化检测；另一组为446例（CXR组），平均年龄67岁，接受后前位胸片检查。两组检查阳性病例将接受进一步组织病理学检查。并分别统计两组阳性结节检出率及肺癌检出率，并行X2检验。结果LDCT—p16组与CXR组分别有96．8％和92．8％的受检者完成了检查。LDCT—p16组中1113％病人可疑肺癌，明显高于CXR组的6．5％（P〈0．05）。其中LDCT—p16组中有7例，CXR组中有2例确诊为肺癌。LDCT—p16组肺癌检出率高于CXR组，但无统计学意义（P〉0．05）。结论低剂量CT联合血清p16基因甲基化检测是一种敏感、安全、可行的筛查早期肺癌的方法，能够取代胸片筛查早期肺癌。

p16基因异常甲基化检测对周围型肺癌的诊断价值

目的:了解周围型肺癌患者外周血血浆中p16基因异常甲基化发生情况及其在周围型肺癌临床辅助诊断中的应用价值。方法:选取56例肺周围型结节手术患者的血浆和组织标本,其中31例为周围型肺癌,25例为肺部良性结节,采用甲基化特异性聚合酶链反应方法检测p16基因启动子的异常甲基化情况。结果:在周围型肺癌患者的血浆和肿瘤组织中,p16基因甲基化检出率分别为64.5%(20/31)和70.9%(22/31);周围型肺癌患者血清、肿瘤组织中p16基因的甲基化异常事件与肿瘤分期、分型无明显相关性。在25例良性肺部疾病患者中,3例血浆和手术切除标本检测出p16基因启动子的异常甲基化存在;良、恶性肺周围型结节的p16基因异常甲基化发生情况差异存在显著性。结论:检测周围型肺癌患者血浆中p16基因异常甲基化情况有可能成为有价值的临床辅助诊断手段。

p16基因甲基化对肺癌早期诊断的临床研究

目的检测肺癌患者支气管灌洗液及全DNA中p16基因甲基化,并探讨其在肺癌早期诊断中的作用。方法利用半巢式甲基化特异性PCR技术,检测26例肺癌患者支气管灌洗液及相应全血中DNA p16基因的异常甲基化状态。结果34.6%(9/26)肺癌组织出现p16基因甲基化,出现甲基化组织对应的血液标本中88.9%(8/9)出现p16基因甲基化。支气管灌洗液中p16基因的甲基化状况与全血中是否出现p16基因甲基化关系密切(P<0.01)。结论肺癌患者支气管灌洗液及血液标本中p16基因甲基化的检测可能有助于肺癌的早期诊断。

甲状腺肿瘤细胞中p16基因的表达和突变

目的:研究抑癌基因p16在甲状腺肿瘤中的表达及突变。方法:采用免疫组织化学法检测60例甲状腺肿瘤细胞中p16蛋白的表达;采用聚合酶链式反应检测甲状腺肿瘤细胞中p16基因的缺失及外显子_15′CpG岛异常甲基化。结果:60例甲状腺肿瘤中p16蛋白阳性表达为46.7%(28/60);30例腺瘤中p16蛋白阳性表达分别为60.0%(18/30);30例腺癌中则为33.3%(10/30)。60例甲状腺肿瘤中p16基因缺失为13.3%(8/60),30例腺癌中p16基因缺失为26.7%(8/30);30例腺瘤中无缺失(0/30),组间比较差异有显著性(P<0.05)。60例甲状腺肿瘤中p16基因外显子_15′CpG岛异常甲基化为15.0%(9/60);30例腺癌中为30.0%(9/30);30例腺瘤中无外显子_15′CpG岛异常甲基化(0/30),组间比较差异有显著性(P<0.001)。结论:抑癌基因p16参与了甲状腺肿瘤的发生发展,p16基因的缺失和外显子_15′CpG岛异常甲基化在甲状腺恶性肿瘤中起一定的作用,并可能是甲状腺肿瘤中p16基因失活的主要机制。

炭末沉着症和p16^(ink4a)基因异常甲基化对小型肺腺癌发生进展的影响

背景与目的炭末沉着症系长期吸入非生产性粉尘而导致各级支气管壁粘膜和肺膜内有炭末斑形成,可致支气管变形及破坏。有研究表明,炭末沉着症与小型肺腺癌的发生和进展密切相关。本研究旨在探讨炭末沉着症与p16ink4a基因异常甲基化修饰程度在小型肺腺癌发生和进展过程中的影响。方法应用Methylation Specific PCR技术检测68例原发性小型肺腺癌患者的癌组织、癌周正常组织中的p16ink4a基因启动子区域的异常甲基化修饰程度;炭末定量分析法来检测患者肺内的炭末沉着量;采用野口氏病理分型。结果重度吸烟者(吸烟指数>600)的平均炭末沉着量明显高于轻度吸烟者(吸烟指数<600)和非吸烟者(P=0.005);重度吸烟者的p16ink4a基因异常甲基化检出率为60%,也明显高于轻度吸烟者和非吸烟者的27%(P=0.023);早期小型肺腺癌的p16ink4a基因异常甲基化检出率低于进展期和低分化小型腺癌,但无统计学意义;p16ink4a基因调控产物表达早期小型腺癌高于低分化小型腺癌(P=0.032)。结论炭末沉着定量分析与p16ink4a基因异常甲基化检测二者结合,有可能应用于对吸烟人群的肺腺癌早期发现和早期诊断。

Effect of 5-Aza-2'-deoxycytidine on the P16 tumor suppressor gene in hepatocellular carcinoma cell line HepG2

INTRODUCTIONHepatocellular carcinoma (HCC) is one of the mostcommon human malignancies worldwide[1,2], and isclosely associated with infection of HBV and HCVand contamination of aflatoxin B1[3-6]. Althoughthe molecular mechanisms of hepatocarcinogenesisremain poorly understood, an increasing number ofgenetic abnormalities have been recognized[7-10],for example, the p16 gene[11,12] the p53gene[13-18], the E-cadherin gene[19], and the c-mycgene[20].

Aberrant p16 promoter hypermethylation in bronchial mucosae as a biomarker for the early detection of lung cancer

Lung cancer is the leading cause of cancer related death in the world and its mortality could be greatly reduced by diagnosis and treatment in its early stages. Effective tools for the early detection of lung cancer and its high risk factors remain a major challenge. Biomarkers that detect lung cancer in its early stages or identify its pretumour lesions, enabling early therapeutic intervention, would be invaluable to improve its dismal prognosis.

控制正常细胞对肺癌细胞P^(16)基因缺失的污染的方法的建立及其应用

目的建立一种能有效提高从混有正常细胞的肿瘤组织中检测Ｐ１６基因纯合缺失的灵敏度的方法，以及探讨该基因的状态与肺癌临床病理的关系。方法将野生型ＤＮＡ与Ｐ１６基因纯合缺失的ＤＮＡ按一定比例混合，并将其有限稀释，以不同量的ＤＮＡ为模板，用聚合酶链反应（ＰＣＲ）扩增Ｐ１６基因第二外显子及内对照基因片断，在此基础上，以特定量肺癌ＤＮＡ为模板，用相同的ＰＣＲ条件对上述片断进行扩增，对扩增出的第二外显子行单链构型多态性（ＳＳＣＰ）分析。结果ＤＮＡ模板为５ｎｇ，野生型ＤＮＡ不超过总ＤＮＡ４０％时，不掩盖Ｐ１６基因纯合缺失。小细胞肺癌，癌旁肺无Ｐ１６基因纯合缺失及突变，５２例非小细胞肺癌中有２１例Ｐ１６基因纯合缺失，３例第二外显子ＳＳＣＰ异常，其中伴淋巴结转移的非小细胞肺癌Ｐ１６基因的纯合缺失率（７２％）显著高于无淋巴结转移者（１６．６％）。同时还发现Ｐ１６基因的异常与非小细胞肺癌的临床病理分级及预后明显相关。Ｐ１６基因缺失的患者术后存活时间显著低于无Ｐ１６基因缺失者。结论控制ＰＣＲ中模板的量有助于提高检测Ｐ１６基因缺失的灵敏度。Ｐ１６基因异常可能参与非小细胞肺癌的恶性进展。