环氧合酶-2和血管内皮生长因子-C与胃癌淋巴管转移

目的　研究环氧合酶 2 (COX 2 )和血管内皮生长因子 (VEGF) C在胃癌组织中的表达及相关性 ,探讨二者在胃癌淋巴管生成和转移中的作用。方法　采用免疫组化方法和逆转录 PCR技术 ,分别检测了 6 4例胃癌石蜡组织中COX 2和VEGF C的表达及其中 2 2例胃癌新鲜组织中二者mRNA的表达。结果　 2 2例胃癌新鲜组织中COX 2和VEGF CmRNA表达阳性率分别为 82 %和73% ,其表达均高于相应的癌旁正常组织 (P <0 0 0 1) ,与 6 4例胃癌石蜡标本COX 2和VEGF C的表达结果较一致。且COX 2和VEGF C表达之间存在明显关联性 (P <0 0 5 )。二者在癌组织中的高表达与肿瘤浸润深度、淋巴结转移等密切相关 (P <0 0 5 )。结论　胃癌组织中有COX 2和VEGF C的高表达 ,而COX 2可能参与VEGF C淋巴管生成通路 ,它们的表达可能在胃癌淋巴管浸润和转移中发挥重要作用     

Notch1及COX2在人胃癌组织中的表达及意义

[目的]探讨Notch1及COX2在胃癌组织中的表达及意义。[方法]收集我院胃癌及癌旁正常胃组织标本115例,采用免疫组化EnVision法测定Notch1和COX2在胃癌和癌旁正常胃组织中的表达,分析其表达水平与胃癌各临床病理指标之间的关系。[结果]Notch1在胃癌和癌旁正常胃组织中的表达分别为73.91%(85/115)和3.48%(4/115),COX2在胃癌和癌旁正常胃组织中的表达分别为89.57%(103/115)和6.96%(8/115),两者差异有统计学意义(P0.01)。Notch1和COX2在胃癌组织中的表达与胃癌的淋巴结转移及TNM分期有关(P0.05)。[结论]Notch1-COX2信号轴可能参与了胃癌的发生、发展和转移。     

TGF-β1和Smad2在胃癌中的表达及意义

目的:检测TGF-β1和Smad2信号在胃癌中的表达,探讨TGF-β1和Smad2在胃癌发生、发展中的作用.方法:采用免疫蛋白印迹(Westernblot)和实时定量PCR检测45例胃癌组织及相应正常组织TGF-β1、Smad2蛋白及mRNA的表达,比较正常对照、癌组织中上述二者表达的差异,并进行统计学分析.结果:TGF-β1在胃癌组织中阳性表达率为77.8%(35/45),在正常组织中为33.3%(15/45),二者比较差异显著(P<0.05);Smd2蛋白在胃癌组织中阳性表达率为73.3%(33/45),在正常组织中为26.7%(12/45),二者比较有显著差异(P<0.05);TGF-β1、Smad2mRNA在胃组织中阳性表达率分别为88.9%(40/45)、84.4%(38/45),均显著高于正常组织(P<0.05).胃癌组织中TGF-β1、Smad2蛋白的表达与病理分级、浸润深度、淋巴结转移、脉管侵犯相关(P<0.05).结论:TGF-β1和Smad2可能在胃癌的发生、发展中发挥作用,并与胃癌的侵袭、转移相关.     

环氧合酶-2表达与幽门螺杆菌相关性胃十二指肠疾病的研究

目的　探讨环氧合酶 2表达与幽门螺杆菌Helicobacterpylori ,H .pylori相关性胃十二指肠疾病的关系 ,并通过抗菌治疗评价根除H pylori感染对胃窦黏膜中COX 2表达的影响。方法　用免疫组化方法半定量检测 2 64例经胃镜和组织病理学检查患有十二指肠球部溃疡、胃溃疡、复合性溃疡、胃癌、单纯性慢性胃炎及胃黏膜正常者的胃窦黏膜COX 2蛋白的表达 ,比较H pylori感染与非感染者之间的差异。对检出的 3 5例H pylori的单纯慢性胃炎进行H pylori抗菌根除治疗 ,比较根除前后胃窦黏膜COX 2蛋白的表达变化。根据 2 0 0 0年 5月全国慢性胃炎研讨会共识意见 (江西 井冈山 )对胃黏膜炎症、活动性、异型增生、肠化生和H pylori密 ,度进行半定量测定。结果　胃黏膜表面上皮、腺上皮细胞和固有层间质细胞的浆中可见COX 2蛋白表达 ,但阳性染色细胞多集中在表层上皮。 2 53例中 ,14 3例H pylori者 (56 52 % )COX 2平均阳性细胞率显著高于 110例H pylori者 (43 48% ) ,(P =0 ) ,各疾病组H pylori患者的COX 2平均阳性细胞率均显著高于H pylori者 (P =0 ) ,各疾病组H pylori患者COX 2平均阳性细胞率也均显著高于正常对照组 (P <0 0 5)。 2 7例H pylori根除后的胃黏膜COX 2平均阳性细胞率明显下降 (P =0 ) ,但仍明显高于正     

不同胃组织中bcl-2蛋白的亚细胞定位及意义

目的　探讨 bcl- 2蛋白在胃癌、癌旁组织中的不同亚细胞定位及其意义。方法　采用 SP免疫组化法检测 4 6例胃癌和 2 5例癌旁组织中 bcl- 2的表达。结果　胃癌、癌旁组织中 bcl- 2表达率分别为 6 0 .87% (2 8/4 6 )、4 8.0 0 % (12 / 2 5 ) ,两者比较无显著差异 (P >0 .0 5 )。癌旁组 bcl- 2在胞浆定位 2例 (8.0 0 % ) ,核膜及混合定位10例 (40 .0 0 % )。胃癌组在胞浆定位 16例 (34.78% ) ,核膜和混合定位 12例 (2 6 .0 9% ) ,两组比较差异有显著性 (P <0 .0 5 )。bcl- 2蛋白在胃癌不同分化程度、病理分期及淋巴结转移中的阳性表达和定位均无统计学意义 (P >0 .0 5 )。结论　 bcl- 2蛋白超表达定位于核膜或混合定位是胃良性病变的标志 ,而单一胞浆定位是引起细胞恶变的一个可能机制     

胃癌雌激素受体与PCNA的关系

目的探讨雌激素在胃癌发生、发展中的作用及临床意义.方法应用流式细胞术检测31例胃癌组织、10例正常胃组织雌激素受体(estrogen receptor,ER)和细胞周期蛋白D1(cyclinD1)表达量;应用免疫组织化学法检测31例胃肠癌组织、10例正常胃肠组织中ER和增殖细胞核抗原(proliferatingcell nuclear,PCNA)蛋白表达.结果流式细胞术定量检测结果表明,胃癌组织ER表达量(FI,1.19±0.23)明显高于正常胃组织(FI,1.00±0.04,P＜0.01);胃癌组织cyclinD1表达量(FI,1.33±0.17)明显高于正常胃组织(FI,1.00±0.09,P＜0.01).胃癌组织ER表达量与cyclinD1表达量存在正相关关系(rs=0.40,P＜0.05).免疫组织化学染色结果表明,胃癌组织ER表达阳性率为45%(14/31),明显高于正常胃组织0%(0/10,P＜0.01);胃癌组织PCNA蛋白表达阳性率为97%(30/31),明显高于正常胃组织0%(0/10,P＜0.01),且胃癌组织ER表达等级与PCNA蛋白表达等级间存在正相关关系(rs=0.44,P＜0.05).结论雌激素在胃癌发生、发展中有促进细胞增殖的作用,部分胃癌很有可能是雌激素依赖性肿瘤.     

大肠癌和大肠腺瘤COX-2和Bcl-2的基因表达及其意义

目的　探讨COX 2及Bcl 2基因在大肠癌和大肠腺瘤组织中的表达及其意义。方法　应用免疫组化ABC法检测 2 8例大肠癌、2 8例大肠腺瘤和 10例正常黏膜中COX 2及Bcl 2表达 ,应用TUNEL法检测细胞凋亡。结果　在大肠癌、大肠腺瘤及正常黏膜中COX 2的阳性表达分别为 82 1%、85 7%和 0 0 %。Bcl 2的阳性表达分别为 75 0 %、78 6%和 2 0 0 %。大肠癌与腺瘤的COX 2及Bcl 2表达均无显著性差异 (P >0 0 5) ,但均显著高于正常黏膜 (P <0 0 1)。大肠癌中凋亡指数明显高于大肠腺瘤 (χ2 =8 80 ,P <0 0 5) ,COX 2和Bcl 2的表达均与大肠腺瘤及大肠癌的细胞凋亡指数呈显著负相关 (腺瘤P <0 0 1;癌P <0 0 5) ,两者均与临床病理特征无相关性 (P >0 0 5) ,大肠癌高、中、低分化各组间及不同Dukles分期 (A、B期和C、D期 )各组间凋亡指数无显著性差异 (P>0 0 5)。结论　COX 2和Bcl 2在大肠腺瘤及大肠癌中表达增强 ,从而抑制了细胞凋亡 ,在大肠腺瘤恶变及大肠癌的发生和发展过程中起到重要作用     

胃癌临床特征与TβRⅡ、COX-2表达的关系

目的 :研究在胃癌与非癌组中转化生长因子 β受体Ⅱ (TβRⅡ )、环氧合酶 2 (COX 2 )的表达 ,以探求胃癌临床特征与TβRⅡ、COX 2表达的关系。方法 :对 1 997～ 2 0 0 2年底经手术病理诊断为胃癌早期 2 9例 ,中期 1 3例及晚期 2 0例进行随访调查。存档蜡块重新制片、读片 ,免疫组织化学S P法染色。检测TβRⅡ、COX 2和与微血管密度 (MVD)在胃癌和非癌组织中的表达情况 ,分析它们与胃癌临床特征的关系。结果 :TβRⅡ表达在不典型增生组与早期胃癌组间 (P <0 .0 5) ,早中期与晚期胃癌组间 (P <0 .0 1 ) ,肿瘤组织不同浸润深度 (P <0 .0 5) ,分化程度 (P <0 .0 5)及有无淋巴结转移 (P <0 .0 1 ) ,各组间差异有显著性。COX 2表达在早期胃癌组与非癌组织相比(P <0 .0 1 ) ,有无淋巴结转移组间 (P <0 .0 5) ,早中期与晚期胃癌组间 (P <0 .0 1 )表达的差异有显著性。TβRⅡ不同表达 (P <0 .0 5)和COX 2不同表达 (P <0 .0 1 )的MVD差异有显著性。COX回归分析显示 ,TβRⅡ是胃癌患者有价值的预后因素。结论 :TβRⅡ、COX 2的表达与MVD有明显的关系 ,与浸润深度、淋巴结转移和预后等胃癌的临床特征有关。TβRⅡ与术后生存率有密切关系 ,可作为胃癌预后的参考指标     

胃癌组织中核因子-κB和环氧合酶-2的表达及其临床意义

背景:有关核因子(NF)-κB和环氧合酶(COX)-2在肿瘤组织中表达的研究虽然较多,但其临床意义和相互关系尚无定论.目的:研究NF-κB和COX-2在胃癌组织中的表达及其关系.方法:采用免疫组化SP法检测142例胃癌组织中NF-κB和COX-2蛋白的表达,以相应的癌旁正常组织(30例)作对照.结果:NF-κB在胃癌组织中的阳性表达率为62.0%,显著高于对照组(P＜0.01);NF-κB的表达与组织学类型、淋巴结转移和远处转移的临床指标呈显著相关(P＜0.05).COX-2在胃癌组织中的阳性率为64.1%,在对照组中无表达,两者比较有显著性差异(P＜0.01),且在淋巴结转移组阳性率显著高于无转移组(P＜0.01).胃癌组织中NF-κB和COX-2的表达呈显著正相关(r=0.380,P＜0.01).结论:NF-κB和COX-2在胃癌的发生、发展中起重要作用,NF-κB可能促进了COX-2的表达.     

不同类型胃息肉及胃癌中环氧化酶-2和P16蛋白的表达及相关性

目的:研究不同类型胃息肉及胃癌中COX-2(环氧化酶-2)和P16蛋白的表达,探讨COX-2、P16蛋白在胃癌发生、发展中的作用及其相互关系.方法:采用S-P免疫组织化学方法检测10例正常胃黏膜,30例非肿瘤性胃息肉(炎性及增生性胃息肉),20例肿瘤性胃息肉(腺瘤性胃息肉)和40例胃癌组织中,COX-2和P16蛋白的表达情况.结果:COX-2表达,在正常胃黏膜、非肿瘤性胃息肉、肿瘤性胃息肉及胃癌中分别为10%,13.33%,45%,75%,胃癌组阳性率与其他三组差异有显著性(P<0.05);P16蛋白表达,在正常胃黏膜、非肿瘤性胃息肉、肿瘤性胃息肉及胃癌中分别为90%,86.67%,60%,32.5%,胃癌组阳性率与其他三组差异有显著性(P<0.05).COX-2、P16蛋白表达与胃癌分化程度、淋巴结转移、呈一定相关性.COX-2与P16蛋白的表达呈负性相关(P<0.05).结论:COX-2、P16蛋白在胃癌发生、发展中起一定作用,可作为判定胃癌生物学行为的有用指标.     

Relationship between expression and distribution of cyclooxygenase-2 and bcl-2 in human gastric adenocarcinoma

AIM: To explore expression and distribution features of COX-2 and bcl-2 in human gastric adenocarcinoma tissues and to study its biological significance. METHODS: Totally 36 human gastric carcinoma samples were enrolled in this study (cardiac adenocarcinoma 16 cases, distal gastric adenocarcinoma 20 cases). The expressions of COX-2 and bcl-2 in cancerous tissues and corresponding para-cancerous tissues were investigated by immunohistochemistry using COX-2 polyclonal antibody and bcl-2 monoclonal antibody. The normal gastric mucosa tissues were used as control. RESULTS: The expressions of COX-2 and bcl-2 in gastric carcinoma were significantly higher than that in the para-cancerous tissues (77.8% vs 47.2%, P<0.01, 80.56% vs 58.33%, P<0.05). The expression of COX-2 in cardiac adenocarcinoma was remarkably higher than that in the distal gastric carcinoma (93.8% vs 65.0%, P<0.01). The expression of COX-2 was mainly localized in the cytoplasm of tumor cells and partly in the nucleus. There is a transition of the COX-2 cytoplasmic positivity to nucleic in tumor cells with the increase of gastric carcinoma pathological grade. Interstitial macrophages, fibroblasts and vascular endothelial cells also expressed COX-2. The tissues with higher expression of COX-2 also expressed high level of bcl-2 protein. CONCLUSION: Abnormal expression pattern of COX-2 within the tissues of human gastric cancer is correlated with tumor location and lymph node metastasis. COX-2 may regulate expression of apoptosis suppressor gene (bcl-2) through interaction of tumor cells and stromal cells and play an important role in the generation and development of tumors, which will be of great help in developing new methods for antitumor therapy.     

Increased expression of cyclooxygenase-2 in first-degree relatives of gastric cancer patients

AIM: To study the expression of cydooxygenase-2 (COX-2) in human gastric cancer tissues and their paired adjacent mucosa, as well as mucosa from gastric antrum and corpus of the first-degree relatives of the recruited cancer patients. METHODS: The expression of COX-2 mRNA in 38 patients with gastric cancer and their 29 first-degree relatives and 18 healthy controls was assessed by the real time RT-PCR. The expression of COX-2 protein was determined by Western blot. RESULTS: A marked increase in COX-2 mRNA expression was found in 20 of 37 (54%) cancerous tissues compared to their respective paired normal mucosa (P<0.001). Interestingly, increased COX-2 mRNA expression was also found in mucosa of the corpus (6/29) and antrum (13/29) of their first-degree relatives. Increased COX-2 mRNA expression was more frequently observed in the antrum biopsies from cancer patients than in the antrum biopsies from healthy controls (P<0.05). In addition, 3 of 23 (13%) patients with atrophic mucosa and 6 of 35 (17%) patients with intestinal metaplasia showed increased COX-2 mRNA expression. Furthermore, COX-2 expression increased in H pylori-positive tissues, especially in antrum mucosa. CONCLUSION: Increased COX-2 expression is involved in gastric carcinogenesis, and may be necessary for maintenance of the malignant phenotype and contribute to Helicobacter pylori-associated malignant transformation.     

Mechanism and clinical significance of cyclooxygenase-2 expression in gastric cancer

AIM: To determine the correlation between methylation status of 5' CpG island of cyclooxygenase-2 (COX-2) gene and protein expression in gastric cancer tissues for distinguishing the molecular characters of gastric cancers. METHODS: Methylation status of 5' CpG island of COX-2 gene was studied by PCR amplification after HpaⅡ and Hha I restrictive enzyme digestion;COX-2 expression was evaluated by immunohistochemical method. RESULTS: Hpa Ⅱ and HhaI site were all methylated in 12 normal gastric mucosa tissues, whereas they were demethylated in 77.27% (34/44) and 84.09% (37/44) gastric cancer tissues,respectively.Expression of COX-2 was detected in 68.18% (30/44) gastric cancer tissues, but no expression was found in normal gastric mucosa tissues. In gastric cancer tissues, COX-2 expression was correlated significantly with HpaⅡ site demethylation (29/30 vs 5/14, P<0.001 and HhaI site demethylation (28/30 vs 9/14,P<0.05). CONCLUSION: The demethylation of 5' CpG island of gene is necessary for COX-2 expression in human gastric cancer. The expression status of COX-2 may provide theoretical basis for COX-2 targeting gastric cancer treatments.     

COX-2, MMP-7 expression in oral lichen planus and oral squamous cell carcinoma

ObjectiveTo observe cyclooxygenase (COX)-2 expression in normal oral mucosa (NOM), oral lichen planus (OLP) and oral squamous cell carcinoma (OSCC) and explore its significance in the incidence of oral cancer.MethodsThe immunohistochemical method and RT-PCR method were applied to detect the expression of COX-2 and MMP-7 in 10 cases with NOM, 33 cases of with OLP and 38 cases with OSCC.ResultsThe expression of COX-2 mRNA in OSCC tissues (68.4%, 26/38) was significantly higher than in the OLP (24.2%, 8/33) and NOM (0.0%, 0/10) (P<0.01). The expression of MMP-7 mRNA in OSCC tissues (65.8%, 25/38) was significantly higher than in the OLP (30.3%, 10/33) and NOM (0.0%, 0/10) (P<0.01). The expression of MMP-7 in OLP was significantly higher than in the NOM (P<0.05). There was no significant expression of COX-2 protein in NOM, and the positive rate was 42.4% (14/33) and 89.5% (34/38) in OLP and OSCC group, respectively. The COX-2 expression in cancer tissues was significantly higher than in NOM and OLP (P<0.05). The MMP-7 protein expression in cancer tissues (84.2%, 32/38) was significantly higher than in NOM (10.0%, 1/10) and in OLP (42.4%, 14/33), and the positive rate in OLP was significantly higher than in NOM (P< 0.01). The COX-2 expression was associated with clinical stage (P<0.05), the MMP-7 expression was associated with clinical stage and lymph node metastasis (P<0.05). The expressions of COX-2 and MMP-7 mRNA were positively correlated with OSCC.ConclusionsThe abnormal expressions of COX-2 and MMP-7 are closely related to the biological behavior of OSCC, the MMP-7 may be induced by COX-2, and further lead to the invasion and metastasis of OSCC.     

DNA ploidy analysis and expression of MMP-9, TIMP-2, and E-cadherin in gastric carcinoma

AIM: To investigate DNA ploidy and expression of MMP-9, TIMP-2, and E-cadherin in gastric carcinoma and to explore the mechanism of invasion and metastasis of gastric carcinoma. METHODS: Immunohistochemical methods were used to detect the expressions of MMP-9, TIMP-2, and E-cadherin in 156 cases, including 99 cases of gastric carcinoma, 16 cases of adjacent noncancerous mucosa, 16 cases of distant metastases and 25 cases of metastatic lymph node (LN) from gastric carcinoma. Flow cytometry DNA ploidy and S-phase fraction (SPF) analysis were performed on 57 cases, including 47 cases of gastric cancer, 6 cases of adjacent noncancerous mucosa, and 4 cases of distant metastatic cancer. RESULTS: The expression of MMP-9 was significantly correlated with Lauren's classification, Borrmann's classification, LN metastasis, tumor metastasis, and TNM stage, as well as depth of invasion (all P<0.05). The positive rate was lower in noncarcinoma than in carcinoma (31.3% vs66.7%, P<0.01). The expression of TIMP-2 was significantly correlated with Borrmann's classification, LN metastasis, and the depth of invasion (all P<0.05), The expression of E-cadherin was significantly correlated with differentiation, Lauren's classification, Borrmann's classification, and LN metastasis, as well as the depth of invasion (P<0,01 or P<0.05). E-cadherin was less expressed in carcinoma than in noncarcinoma (42.4% vs87.5%, P<0.01). There was a positive correlation between MMP-9 and TIMP-2 and a negative correlation between MMP-9 and E-cadherin, but no correlation between TIMP-2 and E-cadherin. Also there was a positive correlation between DNA aneuploid rate and differentiation and LN metastasis. SPF that was higher than 15% was positively correlated with tumor size, differentiation and LN metastasis. And there was a significant difference between carcinoma and noncarcinoma in DNA aneuploid rate and SPF. CONCLUSION: With tumor progression and development of heterogeneity, the abnormal expressions of MMP-9, TIMP-2, and E-cadherin or DNA aneuploid rate or high SPF gradually increases, suggesting that they play a crucial role in gastric carcinoma progression.     

塞来昔布干预对人胃癌细胞E-钙黏蛋白和基质金属蛋白酶-2表达的影响

目的探讨COX-2与E-cadherin、MMP-2之间的相互关系及其参与胃癌细胞侵袭迁移的可能机制。方法应用塞来昔布(celecoxib)对体外培养的人胃癌细胞SGC7901进行干预,采用实时荧光定量反转录PCR检测COX-2、E-cadherin、MMP-2 mRNA的表达;运用免疫荧光标记法结合激光共聚焦荧光显微镜分析E-cadherin的蛋白表达量;应用Transwell法检测细胞侵袭及迁移能力的变化。结果塞来昔布明显抑制体外培养的人胃癌细胞SGC-7901中COX-2 mRNA的表达,E-cadherin mRNA的表达随着COX-2的表达下降而呈浓度与时间依赖性升高,MMP-2 mRNA的表达随着COX-2的表达下降而呈浓度与时间依赖性降低。塞来昔布30μmol/L干预人胃癌细胞SGC7901 24、36、48 h后,激光共聚焦荧光显微镜检测E-cadherin的蛋白表达量明显升高。塞来昔布干预组细胞穿过Transwell小室的细胞数明显少于对照组。结论 COX-2特异性抑制剂塞来昔布通过抑制COX-2的表达,上调E-cadherin的表达,下调MMP-2的表达,抑制体外培养的胃癌细胞SGC7901的侵袭迁移能力。     

Roles of Helicobacter pylori infection and cyclooxygenase-2 expression in gastric carcinogenesis

AIM: Cyclooxygenase (COX)-2 is over expressed in gastrointestinal neoplasm. Helicobacter pylori (H pylori) infection is causally linked to gastric cancer. However, the expression of COX-2 in various stages of H pylori-associated gastric carcinogenesis pathway has not been elucidated. Therefore, the aim of this study was to clarify the role of H pylori induced COX-2 expression during carcinogenesis in the stomach. METHODS: Gastric biopsies from 138 subjects (30 cases of chronic superficial gastritis (CSG), 28 cases of gastric glandular atrophy (GA), 45 cases of gastric mucosal intestinal metaplasia (IM), 12 cases of moderate gastric epithelial dysplasia and 23 cases of gastric cancer) were enrolled. H pylori infection was assessed by a rapid urease test and histological examination (modified Giemsa staining). The expression of COX-1 and COX-2 in human gastric mucosa was detected by immunohistochemical staining. RESULTS: H pylori infection rate was 64.3% in GA and 69.5% in gastric cancer, which was significantly higher than that (36.7%) in CSG (P<0.05). The positive expression rates of COX-2 were 10.0%, 35.7%, 37.8%, 41.7% and 69.5% in CSG, GA, IM, dysplasia and gastric cancer, respectively. From CSG to GA, IM, dysplasia and finally to gastric cancer, expression of COX-2 showed an ascending tendency, whereas COX-1 expression did not change significantly in the gastric mucosa. The level of COX-2 expression in IM and dysplasia was significantly higher in H pylori-positive than in H pylori-negative subjects (P<0.01). CONCLUSION: COX-2 expression induced by H pylori infection is a relatively early event during carcinogenesis in the stomach.     

Expression of nitric oxide synthase in human gastric carcinoma and its relation to p53, PCNA

AIM: To investigate the expression of NOS in gastric carcinoma, and to explore the relationship between the expression of nitric oxide synthases (NOS) and p53, PCNA, pathological features and clinical staging of gastric cancer. METHODS: The activity of NOS protein was investigated in 85 samples of human gastric carcinoma and 25 samples of normal gastric mucosal tissue by biochemical assay. We then examined the expression of NOS, p53, PCNA in 85 samples of human gastric cancer was examined by immunohistochemistry, and NOS mRNA expression in 85 gastric cancer tissue specimens by In situ hybridization. RESULTS: Biochemical assay showed that the activity of NOS was significantly higher in gastric carcinoma than in normal gastric mucosal tissues (t=0.4161, P＜0.01). Immunohistochemistry revealed that endothelial nitric oxide synthase (eNOS) expressed in all samples of normal gastric mucosa, but only 6 cases of 85 gastric cancer specimens showed weak positive immunohistochemical reactions to eNOS (20%). Inducible nitric oxide synthase (iNOS) was expressed strongly in human gastric carcinoma (81.2%). In situ hybridization analysis showed that iNOS mRNA expression was significantly stronger than eNOS mRNA expression in gastric cancer tissue (X~2 = 10.23, P＜0.01). The expression of iNOS in gastric cancer was associated with differentiation, clinical stages or lymph node metastases (r=0.3426,P＜0.05). However, iNOS expression did not correlate with histological classifications and morphological types. The expression of iNOS was significantly correlated with p53 or PCNA expression (r=0.3612, P＜0.05). The expression of neuronal nitric oxide synthase (nNOS) was not examined by immunohistochemistry and in situ hybridization in gastric cancer specimens and normal gastric mucosa. CONCLUSION: In human gastric cancer, there is an enhanced expression of iNOS, but not of eNOS. NOS promotes the proliferation of tumor cells and plays an important role in gastric cancer spread. Inactivation of antioncogene p53 and overexpression of iNOS might play a synergetic role in the process of carcinogenesis of human gastric carcinoma.