Expression of p16, cyclin D<Subscript>1</Subscript> and RB protein in gastric carcinoma and premalignant lesions

Objective: To investigate the expression of p16, cyclin D₁ and Rb protein in gastric carcinoma and premalignant lesions including dysplastic gastric mucosa and intestinal metaplasia gastric mucosa. Methods: Using SP immunohistochemical methods, the expression of p16, cyclin D1 and Rb proteins was detected in 10 specimens of normal gastric mucosa, 15 specimens of dysplastic gastric mucosa, 15 specimens of intestinal metaplasia gastric mucosa, 30 specimens of gastric carcinoma. The clinical characteristics of the 30 patients with gastric carcinoma were analysed to explore the relationship between the parameter detected and biological action of gastric cancer. Results: Expression of p16 protein was detected in 90% of normal gastric mucosa, 86.67% of dysplastic gastric mucosa, 86.67% of intestinal metaplasia gastric mucosa, 36.67% of gastric carcinoma. The positive rate of p16 protein expression in gastric carcinoma is significantly lower than that in normal gastric mucosa and gastric premalignant lesions mucosa (P<0.01). Expression of cyclin D₁ protein was detected in 10% of normal gastric mucosa, 20% of dysplastic gastric mucosa, 20% of intestinal metaplasia gastric mucosa, 53.33% of gastric carcinoma. The positive rate of cyclin D₁, protein expression in gastric carcinoma is significantly higher than that in normal gastric mucosa and gastric premalignant lesions mucosa (P<0.05). Expression of Rb protein was detected in 90% of normal gastric mucosa, 80% of dysplastic gastric mucosa, 80% of intestinal metaplasia gastric mucosa, 50% of gastric carcinoma. The positive rate of Rb protein expression in gastric carcinoma is significantly lower than that in normal gastric mucosa (P<0.05). The expression of p16, cyclin D₁ gene were associated with the degree of differentiation of gastric carcinoma, lymphnodes metastasis and distant metastasis. Conclusion: p16, Cyclin D₁ and Rb gene play important role in gastric carcinoma genesis. The expression of p16, cyclin D₁ and Rb gene have some value to the diagnosis at earlier stage of gastric cancer. Detection of expression of p16, cyclin D₁ gene would be helpful to judge the prognosis of gastric cancer. Biography: MIAO Lin (1966–), male, master of medicine, associate professor, Second Affiliated Hospital, Nanjing Medical University, majors in gastroenterological cancer.     

人胃癌及癌前病变中NF-KappaB和c-myc蛋白的表达与意义

 目的　探讨胃癌及癌前病变中NF κB亚单位 p6 5蛋白和c myc蛋白的表达及相互关系。 方法　用免疫组化法检测 4 1例胃癌及 2 5例相应非癌组织的 p6 5和c myc蛋白。 结果　 (1)正常胃粘膜→肠型化生→不典型增生→胃癌中 ,两种蛋白的阳性表达率渐次升高 ,且增生组、胃癌组与正常组相比差异分别有显著性 ,肠化与胃癌组间也有显著性差异 (P <0 .0 5 ) ;(2 )胃癌中 ,两种蛋白的表达在低未分化、进展期、有淋巴结转移和浸润至浆膜层的肿瘤中显著增高 (P <0 .0 5 ) ;(3)肠化、增生和胃癌中 ,两者的表达分别具有中到强正相关 (rs=0 .6 12～ 0 .84 5 ,P <0 .0 1)。结论　NF κBp6 5蛋白活性表达的增加是胃癌发生中的早期事件 ,c myc基因产物可能作为其效应子 ,在胃癌的发生发展中发挥重要作用     

Expression and significance of p53 and mdm2 in atypical intestinal metaplasia and gastric carcinoma

Subtypes of intestinal metaplasia may have different manifestations in the carcinogenesis of gastric mucosa. The present study aimed to investigate expression of murine double minute gene 2 (mdm2) in atypical intestinal metaplasia (AIM) and its relationship to gastric carcinoma. Intestinal metaplasia (IM) specimens were obtained from 58 cases. Using a novel classification of IM, the specimens were classified according to morphological changes exhibited in the gastric mucosa; specifically, atypical intestinal metaplasia (AIM) and simple intestinal metaplasia (SIM). The gatric carcinoma specimens were then compared with types I, II and III IM based on different substances present in the mucous. Envision immunohistochemical technique was applied to the detection of the expression of p53 and mdm2 in 58 IM and 30 gastric carcinoma cases. Expression of both p53 and mdm2 proteins was found to be higher in gastric carcinomas (p53, 56.67%, 17/30 and mdm2, 53.33%, 16/30) and AIM (p53, 51.85%, 14/27 and mdm2, 51.85%, 14/27) as compared to SIM (p53, 25.81%, 8/31 and mdm2, 19.35%, 6/31) (P<0.05). A similar pattern of expression of mdm2 protein was found in type I (36.84%, 7/19), type II (38.46%, 10/26) and type III (23.08%, 3/13) IM and gastric carcinoma (53.33%, 16/30). p53 expression was higher in gastric carcinoma (56.67%) compared to type I IM (26.32%) (P<0.05). However, no differences were evident among type II (42.31%, 11/26), type III (46.15%, 6/13) IM and gastric carcinoma. AIM may reveal the precancerous nature of gastric carcinoma more clearly than SIM or the conventional IM subtypes. Additionally, AIM may be involved as a preneoplastic lesion and therefore be an effective indicator in the clinical follow-up of gastric carcinoma patients.     

Alterations of Rb, p16(INK4A) and cyclin D1 in the tumorigenesis of oral squamous cell carcinomas

Immunohistochemical analysis of Rb, p16(INK4A) and cyclin D1 expression was performed on 78 oral squamous cell carcinoma (SCC), 46 leukoplakia, and 20 normal mucosa. Rb and p16(INK4A) expression were observed in all normal mucosa and most of leukoplakia. Lack of Rb and p16(INK4A) was observed in 56.4 and 67.9% of SCC, respectively. The overexpression of cyclin D1 was not observed in normal mucosa and was observed in 35.9% of SCC. A strong reciprocal relationship between Rb and p16(INK4A) expression was observed in oral SCC, and all these SCC cases have at least one of the alterations in the Rb pathway.     

Cell cycle proteins and the development of oral squamous cell carcinoma

Expression of cell cycle regulatory proteins was evaluated in premalignant and malignant oral epithelial lesions, to test the hypothesis that protein regulation of the cell cycle may be altered in the development of oral squamous cell carcinoma. Archived paraffin-embedded specimens (n = 90) from 25 patients with recurrent or persistent lesions were evaluated in immunohistochemically stained sections for cell cycle regulatory proteins p53, Rb, Cyclin D1, p27, and p21. The cell cycle was also evaluated by expression of nuclear protein Ki 67. Sections were graded semiquantitatively using a 0-3 + scale to indicate the percentage of positively stained cells. The initial histologic diagnosis for 17/25 patients was either focal keratosis, mild dysplasia, or moderate dysplasia; the initial diagnosis for the remaining eight patients ranged from severe dysplasia to moderately differentiated squamous cell carcinoma. Thirty-three of 90 specimens showed positive p53 expression, 11 of which were dysplasias. Eighty-nine of 90 specimens, from all stages of disease, showed positive Rb expression. Twenty-three of 90 specimens showed positive Cyclin D1 expression, typically in the later stages (carcinoma) of a patient's disease. Eighty-four of 90 specimens showed positive p21 expression; while 55 of 90 specimens were positive for p27. In control mucosa, p27 was highly expressed, while Rb and p21 proteins were expressed at relatively low levels; p53 and Cyclin D1 proteins were largely absent. Generally, staining of p53, Rb, p21, and Ki 67 increased with time in serial biopsies, while p27 showed decreased staining with disease progression. These data show that cell cycle regulatory proteins are altered in both premalignant and malignant disease, and that protein phenotypes are heterogeneous. P53 expression is seen early, and Cyclin D1 expression is seen late in the development of oral premalignant and malignant disease. Expression of p53, Rb, p21 and Ki67 increased, while p27 decreased, with disease progression.     

p21~(WAF1)基因在胃癌及癌前病变中表达的临床病理意义

 目的 探讨ｐ２１ＷＡＦ１蛋白表达与胃癌发生、发展、浸润转移及临床分期的关系。方法 采用 Ｓ－Ｐ免疫组化法，分别检测２０例正常胃粘膜、４０例不典型增生胃粘膜和１０８例胃癌ｐ２１ＷＡＦ１蛋白表达。结果ｐ２１ＷＡＦ１阳性表达率：正常与不典型增生胃粘膜分别为 １００％、９２％，显著高于胃癌 ３９％（Ｐ ＜０．０５）；高分化腺癌６３％，分别与低分化腺癌３５％、未分化癌２６％、粘液癌３０％及印戒细胞癌２０％比较，皆具有显著性差异（Ｐ＜０．０５）；临床Ⅰ期６０％和Ⅱ期５６％显著高于Ⅲ期２７％和Ⅳ期２２％（Ｐ＜０．０５）；伴淋巴结转移３５％与未转移６２％有显著差异（Ｐ＜ ０．０５）；浸润浅肌层 ６０％较浸润深肌层 ３５％差异有显著性意义（Ｐ＜ ０．０５）而与性别、年龄无关。结论ｐ２１ＷＡＦ１蛋白失表达与胃癌发生、分化程度、浸润、淋巴结转移及临床分期相关。     

p16,Cyclin D1在胃癌发生过程中的表达

研究ｐ１６，ＣｙｃｌｉｎＤ１在胃癌发生过程中的表达。方法：采用免疫组化ＡＢＣ法，检测胃癌、不典型增生、萎缩性胃炎及正常胃粘膜组织Ｐ１６和ＣｙｃｌｉｎＤ１的表达。结论：Ｐ１６和ＣｈｃｌｉｎＤ１在胃上皮癌变过程中起着重要作用，其在胃癌中的反向表达趋势提人才是可能存在相互抑制机制。     

Expression of Human Telomerase RNA Is an Early Event of Stomach Carcinogenesis

Expression of human telomerase RNA (hTR) and telomerase activity in gastric cancer and corresponding non-cancerous mucosa were studied. Telomerase activity was detected in 23 (88%) of 26 carcinoma tissues. Although all tumor specimens and non-cancerous mucosa expressed various levels of hTR, 21 (81%) of 26 cases expressed hTR at a higher level in the tumor than that in the corresponding mucosa. All 8 gastric carcinoma cell lines also expressed hTR at high levels. Nine (35%) of 26 non-cancerous mucosa showed telomerase activity and all of them contained intestinal metaplasia. The incidence of telomerase-positive mucosa in grade 2 intestinal metaplasia was significantly higher than that in grade 0 or grade 1 intestinal metaplasia, whereas hTR overexpression was found in grade 0 or grade 1 intestinal metaplasia as well as grade 2 intestinal metaplasia. The degree of Heticobacter pylori infection increased in parallel with the level of hTR expression and telomerase positivity. These results overall suggest that Helicobacter pylori infection may he a strong trigger for hTR overexpression in intestinal metaplasia, and this may lead to telomerase reactivation.     

Distinctive patterns of gene expression in premalignant gastric mucosa and gastric cancer

Current epidemiological evidence supports a pathogenetic model of gastric cancer involving intermediate stages that include chronic gastritis and intestinal metaplasia. This study explores the molecular features of gastric cancer and premalignant stages using DNA microarray-based gene expression profiling and relates these findings to clinical, pathological, and ethnic parameters. A total of 124 tumor and adjacent mucosa samples were analyzed using spotted cDNA microarrays containing 9381 nonredundant gene elements. Tumor specimens were diffuse, intestinal, or mixed gastric cancer and adjacent mucosa, which generally displayed signs of chronic gastritis or intestinal metaplasia. Expression patterns could be discerned that readily defined premalignant and tumor subtypes. Chronic gastritis exhibits a pronounced mitochondrial gene expression signature, which may be linked to Helicobacter pylori pathogenesis. Intestinal metaplasia was associated with increased expression of many intestinal differentiation genes, many of which were not overexpressed in tumors. Samples were obtained from 91 Australian and 33 Chinese patients to explore potential variation in gene expression between these populations. Despite differences in the incidence, and potentially the etiology, of gastric cancer between these ethnic groups, we found the tumors to be molecularly similar. The identification of molecular signatures that are characteristic of subtypes of gastric cancer and associated premalignant changes should enable further analysis of the steps involved in the initiation and progression of this disease.     

Villin蛋白的表达及其与贲门腺癌的关系

目的 探讨Villin蛋白在贲门肠化中的作用及其与贲门腺癌(GCA)发生、发展的关系.方法 采用免疫组织化学S-P法检测128例胃镜活检及手术切除的GCA及癌旁肠化组织中Villin蛋白的表达,其中贲门肠化组织25例、肠化伴不典型增生组织48例,GCA组织55例,并选取15例胃镜普查正常贲门组织作为对照.结果 Villin蛋白在正常贲门组织中无阳性表达,在贲门肠化组织中的阳性表达率为76.0%(19/25),肠化伴不典型增生组织中的阳性表达率为60.4%(29/48),GCA组织中的阳性表达率为36.4%(20/55),比较差异有统计学意义(P<0.05).Villin蛋白的表达与GCA的分化程度有关(P<0.05).结论 Villin蛋白参与了贲门组织早期肠化和GCA的发生,并在GCA的细胞分化中起重要作用.     

胃癌、癌前病变组织中p53蛋白表达的临床意义

目的探讨胃癌及癌前病变组织中p53蛋白表达的临床意义.方法采用间接免疫荧光标记染色和流式细胞术,检测并比较10例正常胃粘膜、13例浅表性胃炎、10例肠上皮化生、11例不典型增生及16例胃癌组织中p53蛋白的表达水平.以DNA指数、增殖指数(PI)、荧光指数(FI)为分析指标.结果胃癌、不典型增生及肠上皮化生的FI值分别为1.866±0.096、1.143±0.060、1.050±0.074,与正常胃粘膜(0.602±0.077)比较,均有显著性差异(P＜0.05),与浅表性胃炎(0.898±0.052)比较,也有显著性差异(P＜0.05).胃癌组织的FI值高于不典型增生及肠上皮化生(P＜0.05).不典型增生组织p53蛋白阳性率为25.0%(2/8),胃癌为68.4%(13/19),在不典型增生及胃癌组织中,其异倍体的FI值、PI值和p53蛋白阳性率与二倍体者比较,均有显著性差异(P＜0.05).结论胃癌组织p53蛋白的表达水平高于癌前病变及正常胃粘膜组织;随病变向恶性转化,p53蛋白表达水平、PI值及异倍体率均增高.因此,检测p53蛋白表达水平对胃癌的诊断具有一定意义.     

p27蛋白及cyclin B1在慢性胃病及胃癌患者胃粘膜中的表达及其临床意义

目的 研究p27蛋白及cyclin B1在慢性胃病及胃癌患者胃粘膜组织中的表达水平,探讨p27蛋白及cyc-lin B1的表达与胃癌演变的关系.方法 采用免疫组织化学SP法,检测慢性非萎缩性胃炎、慢性萎缩性胃炎、肠上皮化生、非典型增生及胃癌患者胃粘膜组织中p27与cyclin B1的表达水平,并进行临床分析.结果 在慢性非萎缩性胃炎、慢性萎缩性胃炎、肠上皮化生、非典型增生、胃癌的演变过程中,p27蛋白表达水平呈现逐级降低的变化规律,cyclin B1表达水平呈现逐级升高的变化规律,两者的变化呈负相关.结论 p27蛋白及cyclin B1在胃粘膜中的表达水平与慢性胃病、胃癌前病变、胃癌的发生发展有关,其在胃癌的演变过程中起着重要的作用.     

幽门螺旋杆菌感染胃黏膜COX-2和P-gp表达与胃癌发生

背景与目的通过检测幽门螺旋杆菌(Helicobacter Pylori,H.pylori)感染胃粘膜组织环氧合酶-2(Cyclooxygenase-2,COX-2)和多药耐药-1(Multidrug resistance-1,MDR-1)基因表达产物P糖蛋白(P-glycoprotein,P-gp)表达,探讨幽门螺旋杆菌相关胃癌的发生机制,以及P-gp高表达的机制。材料与方法慢性胃炎155例(30例慢性浅表性、40例慢性萎缩性、45例肠化、40例非典型增生)及胃癌80例(肠型40例,弥漫型40例),COX-2和P-gp表达检测选择免疫组化S-P法,H.pylori感染检测采用快速脲素酶及改良Giemsa染色方法。结果H.pylori阳性感染率、COX-2和P-gp的阳性表达率,肠型胃癌均明显高于弥漫型胃癌(P<0.01)。慢性萎缩性胃炎、肠化、非典型增生及肠型胃癌中H.pylori感染与COX-2的表达呈正相关(P<0.01)。H.pylori感染的慢性浅表性胃炎、慢性萎缩性胃炎、肠化、非典型增生及肠型胃癌中COX-2的表达与P-gp的表达也均呈正相关(P<0.01)。结论H.pylori依赖的COX-2表达与P-gp表达有关,可能有助于胃癌形成以及胃癌对化疗抵制。     

Alterations of Rb pathway (Rb-p16INK4-cyclin D1) in preinvasive bronchial lesions.

Lung cancer results from a stepwise accumulation of genetic and molecular abnormalities with unknown temporal relationships to precursor bronchial lesions. In a search for biomarkers of malignant progression, we analyzed the expression of the tumor suppressor gene Rb and of the proteins regulating its phosphorylation and function in G1 arrest, p16INK4A and cyclin D1, in preinvasive bronchial lesions accompanying cancer in 75 patients, in comparison with similar lesions in 22 patients with no cancer history. Rb was constantly expressed in preinvasive lesions, including carcinoma in situ (CIS). In contrast, p16 expression was lost in moderate dysplasia (12%) and in CIS (30%) in patients with lung cancer. p16 loss occurred exclusively in patients who displayed loss of p16 expression in their related invasive carcinoma. Loss of p16 expression was not seen in nine patients with dysplasia but no cancer progression. Cyclin D1 overexpression was seen in hyperplasia and metaplasia (6%), mild dysplasia (17%), moderate dysplasia (46%), and CIS (38%) in patients with cancer but was lost in 5% of the patients during the process of invasion; it was also observed in patients with no cancer progression (14%). Our results indicate that Rb protein function can be invalidated before invasion through alteration of the Rb phosphorylation pathway, by p16 inhibition, and/or by cyclin D1 overexpression and suggest a role for p16 and cyclin D1 deregulation in progression of preinvasive bronchial lesions to invasive carcinoma.     

Significance of Skp2 expression in human gastric carcinoma and the relationship between Skp2, p27 and PTEN expression

Objective： S-phase kinase-associated protein 2 （Skp2） is a positive regulator of G1-S transition and promotes ubiquitin-mediated proteolysis of the cyclin-dependent kinase inhibitor p27. Its overexpression has been implicated in cell transformation and oncogenesis. In this study, we investigated significance of Skp2 expression in human gastric carcinoma and the relationship between Skp2, p27 and PTEN expression. Methods： Immunohistochemical analysis was performed on 138 surgical resected primary gastric carcinoma specimens, 102 paired metastasis carcinoma tissue specimens in lymph node from the same set of 138 surgical resected primary gastric carcinoma specimens, 30 dysplasia specimens, 30 intestinal metaplasia specimens, and 20 normal gastric mucosa specimens for Skp2 and performed on the same set of 138 surgical resected primary gastric carcinoma specimens for p27 and PTEN. Results： Skp2 labeling frequency % was increased dramatically in intestinal metaplasia, dysplasia, and primary gastric carcinoma compared with normal gastric mucosa （P=0.000, all the same）. Skp2 labeling frequency % in metastasis gastric carcinoma in lymph node was significantly higher than primary gastric carcinoma （P=0.037）. Skp2 labeling frequency % was positively associated with differentiated degree （rho=0.315, P=0.000）, vessel invasion （rho=0.303, P=0.000） and lymph node metastasis （rho=0.254, P=0.000） respectively. An inverse correlation of Skp2 was observed with both its biochemical target p27 expression in gastric carcinoma （rho=-0.451, P=0.000） and with its putative negative regulator, the PTEN tumor suppressor protein （rho=-0.480, P=0.000）. p27 expression had positive relationship with PTEN expression in gastric carcinoma （rho=0.642, P=0.000）. Conclusion： Skp2 overexpression is correlated with carcinogenesis and progression of gastric carcinoma： elevated Skp2 expression is correlated with decreased p27 and PTEN in gastric carcinoma, and p27 expression is parallel with PTEN expression. These suggest that PTEN may regulate expression of p27 through the Skp2 pathway, and the effects of Skp2, p27 and PTEN together play an important role in carcinogenesis and progression of gastric carcinoma.     

胃癌组织Skp2表达的意义及其与P27、PTEN表达的关系

背景与目的:S期激酶相关蛋白2(S-phaseKinase-associatedProtein2,Skp2)促进泛素介导的细胞周期素依赖激酶抑制剂P27蛋白降解,是细胞G1-S期转化所必需。研究发现Skp2过表达参与细胞转化和肿瘤的形成。本研究旨在探讨人胃癌Skp2表达的意义及Skp2与P27和PTEN表达的关系。方法:采用免疫组化法检测胃癌组织及配对癌旁胃粘膜138例、配对淋巴结转移癌组织102例、非典型增生30例、肠上皮化生30例、慢性浅表性胃炎10例和正常胃粘膜5例Skp2表达及138例胃癌P27和PTEN的表达。结果:Skp2的标记率(%)在肠化(12.68±0.86)及癌旁胃粘膜(19.32±1.22)均明显高于慢性浅表性胃炎(0.53±0.13)及正常胃粘膜(0.47±0.19)(P<0.001),后两者无显著性差异(P﹥0.05);非典型增生(16.74±0.82)明显高于肠化(P<0.001);原发胃癌(31.34±2.17)明显高于非典型增生及癌旁胃粘膜(P<0.001);淋巴结转移胃癌组织(39.76±2.00)明显高于原发胃癌(P=0.037)。胃癌Skp2标记率与分化程度(rs=0.315,P=0.000)、脉管内瘤栓(rs=0.303,P=0.000)及淋巴结转移(rs=0.254,P=0.000)呈正相关。胃癌Skp2表达与靶蛋白P27表达(rs=-0.451,P=0.000)和肿瘤抑制蛋白PTEN(rs=-0.480,P=0.000)表达呈负相关;胃癌PTEN表达与P27表达呈正相关(rs=0.642,P=0.000)。结论:胃癌Skp2蛋白过表达与P27蛋白降解及PTEN蛋白低表达有关,提示Skp2蛋白过表达可能是胃癌发生和发展的一个重要原因。     

Carcinogenesis of intestinal-type gastric cancer and colorectal cancer is commonly accompanied by expression of brain (fetal)-type glycogen phosphorylase.

Our previous studies have demonstrated the significant enzymatic activity of glycogen phosphorylase (GP) in the gastric carcinoma and proliferating cells of particular intestinal metaplasia (IM). This paper reviewed the identification of the GP isoform in the gastrointestinal carcinoma, and the investigation on the role of this molecule in the gastrointestinal carcinogenesis. The only isoform expressed in gastric cancer was brain-type GP (BGP) using polymerase chain reaction (PCR) analysis. The expression of BGP, oncogene products and proliferating cell nuclear antigen in the gastric and colorectal carcinomas, their premalignant lesions, and the normal mucosa were examined using 136 gastric and 96 colorectal surgically resected specimens, and 55 endoscopically resected colorectal adenomas. The BGP visualized by immunohistochemistry was commonly present in intestinal-type gastric (80.6%) and colorectal (83.3%) carcinomas, whereas no BGP expression was seen in the normal human gastric and large intestinal mucosa except in the BGP foci described below. IMs with BGP had close correlation with intestinal-type gastric carcinoma, and some of them coexpressed accumulated p53 protein. The expression of BGP during 'adenoma carcinoma sequence' (ACS) showed excellent correlation with the increased dysplasia and was found prior to p53 expression. Positive staining in overtly normal looking colonic mucosa (BGP foci) was observed mainly around carcinomas without any adenoma component, and frequent p53 mutation (41.2%) was detected in the BGP foci using PCR-single strand conformation polymorphism analysis. It is suggested that BGP is a novel biomarker for carcinogenesis in the intestinal-type gastric carcinoma and in both of the pathways of ACS and the 'de novo' colorectal carcinoma.     

CpG island methylation in premalignant stages of gastric carcinoma

There are limited reports on methylation analysis of the premalignant lesions of gastric carcinoma thus far. This is despite the fact that gastric carcinoma is one of the tumors with a high frequency of CpG island hypermethylation. To determine the frequency and timing of hypermethylation during multistep gastric carcinogenesis, non-neoplastic gastric mucosa (n = 118), adenomas (n = 61), and carcinomas (n = 64) were analyzed for their p16, human Mut L homologue 1 (hMLH1), death-associated protein (DAP)-kinase, thromobospondin-1 (THBS1), and tissue inhibitor of metalloproteinase 3 (TIMP-3) methylation status using methylation-specific PCR. Three different classes of methylation behaviors were found in the five tested genes. DAP-kinase was methylated at a similar frequency in all four stages, whereas hMLH1 and p16 were methylated in cancer samples (20.3% and 42.2%, respectively) more frequently than in intestinal metaplasia (6.3% and 2.1%, respectively) or adenomas (9.8% and 11.5%, respectively). However, hMLH1 and p16 were not methylated in chronic gastritis. THBS-1 and TIMP-3 were methylated in all stages but showed a marked increase in hypermethylation frequency from chronic gastritis (10.1% and 14.5%, respectively) to intestinal metaplasia (34.7% and 36.7%, respectively; P < 0.05) and from adenomas (28.3% and 26.7%, respectively) to carcinomas (48.4% and 57.4%, respectively: P < 0.05). The hMLH1, THBS1, and TIMP-3 hypermethylation frequencies were similar in both intestinal metaplasia and adenomas, but the p16 hypermethylation frequency tended to be higher in adenomas (11.5%) than in intestinal metaplasia (2.1%; P = 0.073). The average number of methylated genes was 0.6, 1.1, 1.1, and 2.0 per five genes per sample in chronic gastritis, intestinal metaplasia, adenomas, and carcinomas, respectively. This shows a marked increase in methylated genes from non-metaplastic mucosa to intestinal metaplasia (P = 0.001) as well as from premalignant lesions to carcinomas (P = 0.002). These results suggest that CpG island hypermethylation occur early in multistep gastric carcinogenesis and tend to accumulate along the multistep carcinogenesis.     

Mucin gene expression and cell differentiation in human normal, premalignant and malignant esophagus

Esophageal carcinoma includes squamous cell carcinoma and Barrett's adenocarcinoma. The latter usually develops from a premalignant lesion named Barrett's esophagus. MUC genes are known to be specifically expressed in the normal, premalignant and malignant epithelia of various tissues. The aim of this study was to establish the pattern of MUC gene expression in the esophageal mucosa under normal conditions, and under pathological conditions such as squamous cell carcinoma, Barrett's esophagus and adenocarcinoma. Samples of esophageal control mucosa, metaplastic and malignant tissues were obtained from 40 patients undergoing esophagectomy for squamous cell carcinoma (n = 17), or Barrett's esophagus with adenocarcinoma (n = 23). In situ hybridization and northern blot were used with probes specific for the MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7 genes to assess their expression in these samples. Submucosal glands of control esophageal mucosa expressed MUC5B, whereas MUC1 and MUC4 were found in both control epithelium and squamous cell carcinoma. MUC4 expression correlated with squamous cell differentiation. Barrett's adenocarcinoma exhibited various patterns of MUC gene expression, the strongest being in the well-differentiated mucinous adenocarcinomas. Barrett's metaplasia was also associated with a specific MUC gene expression pattern, since the gastric apomucin mRNAs, MUC5AC and MUC6, were expressed in gastric metaplasia, and the intestinal apomucin mRNAs, MUC3, MUC4 and mostly MUC2, in intestinal metaplasia. Residual expression of gastric apomucin mRNAs was found in intestinal metaplasia. From these results, we conclude that MUC genes can be considered reliable phenotypic markers of the esophageal cell differentiation, thus providing new insight into the development of Barrett's esophagus.