Deficiency of Adenomatous Polyposis Coli protein in sporadic colorectal adenomas and its associations with clinical phenotype and histology

AIM： To evaluate the frequency of the loss of the Adenomatous Polyposis Coil （APC） protein and to compare the APC status with the characteristics of colorectal adenomas. METHODS： Immunohistochemical analysis of the APC protein was performed on 118 adenomas and the results were compared with parameters of malignant potential, location of adenomas, macroscopic appearance and age of the patients. RESULTS： A complete loss of the APC protein was found in 28 （24%） adenomas, while 90 （76%） were APC positive. The mean size of adenomas was 13.5± 14.2 mm （95% CI 10.5-16.5） in APC-positive, and 13.8 ±15.5 mm （95% CI 7.8-19.8） in APC-negative adenomas （P = 0.364）. Statistical analysis revealed no difference between APC-positive and negative adenomas as to the histological type （P = 0.327） and grade of dysplasia （P =0.494）. We found that even advanced adenomas did not differ in their APC status from the non-advanced tumors （P = 0.414）. Finally, no difference was found when the location （P = 0.157）, macroscopic appearance （P = 0.571） and age of patients （P = 0.438） were analysed and compared between both APC positive and negative adenomas. CONCLUSION： Most adenomas expressed full-length APC protein, suggesting that protein expression is not a reliable marker for assessment of APC gene mutation. Complete loss of APC protein did not influence morphology, location, or appearance of adenomas, nor was it affected by the patient＇s age.

Aspirin-induced long-term tumor remission in hepatocellular carcinoma with adenomatous polyposis coli stop-gain mutation:A case report

BACKGROUND Targeted therapy based on pathway analysis of hepatitis B-related hepatocellular carcinoma(HCC)may be a promising remedy.CASE SUMMARY The present case involved an advanced hepatocellular carcinoma(HCC)patient who did not receive local regional therapy and was intolerant to sorafenib.Total RNA extracted from the patient’s tumor tissue was used to obtain the gene mutation profile.The c.3676A>T and c.4402A>T stop-gain mutations in adenomatous polyposis coli(APC)were the most prevalent(42.2%and 35.1%,respectively).MutationMapper analysis indicated that the functional domain of APC was lost in the two APC mutant genes.APC is a major suppressor of the Wnt signaling pathway.Thus,the Wnt pathway was exclusively activated due to APC dysfunction,as other elements of this pathway were not found to be mutated.Aspirin has been reported to suppress the Wnt pathway by inducingβ-catenin phosphorylation through the activation of glycogen synthase kinase 3 beta via cyclooxygenase-2 pathway inhibition.Therefore,aspirin was administered to the patient,which achieved four years of disease control.CONCLUSION Exclusive mutations of APC of all the Wnt pathway elements could be a therapeutic target in HCC,with aspirin as an effective treatment option.

Hepatocellular adenoma associated with familial adenomatous polyposis coli

Hepatocellular adenoma (HCA) is a benign liver tumor that most frequently occurs in young women using oral contraceptives. We report a rare case of HCA in a 29 years old female with familial adenomatous polyposis (FAP). The first proband was her sister, who under-went a total colectomy and was genetically diagnosed as FAP. A tumor, 3.0 cm in diameter, was detected in the right lobe of the liver during a screening study for FAP. A colonoscopy and gastroendoscopy revealed numerous adenomatous polyps without carcinoma. The patient underwent a total colectomy and ileoanal anastomosis and hepatic posterior sectoriectomy. The pathological findings of the liver tumor were compatible with HCA. The resected specimen of the colon revealed multiple colonic adenomatous polyps. Examination of genetic alteration revealed a germ-line mutation of the adenomatous polyposis coli (APC) gene. Inactivation of the second APC allele was not found. Other genetic alterations in the hepatocyte nuclear factor 1 alpha and β-catenin gene, which are reported to be associated with HCA, were not detected. Although FAP is reported to be complicated with various neoplasias in extracolic organs, only six cases of HCA associated with FAP, including the present case, have been reported. Additional reports will establish the precise mechanisms of HCA development in FAP patients.

APC gene mutations in Chinese familial adenomatous polyposis patients

AIM:To study the characteristics of APC(adenomatous polyposis coli)gene germline mutation in Chinese patients with familial adenomatous polyposis(FAP).METHODS:APC gene from 14 FAP families was amplified by polymerase chain reaction(PCR)and underwent direct sequencing to determine the micromutation type.For the samples without micromutation,the large fragment deletion of APC gene was examined by multiplex ligation-dependent probe amplification(MLPA).RESULTS:There were gene micromutations in 9 families with a micromutation detection rate of 64.3%(9/14),including 6 frameshift mutations(66.7%),1 nonsense mutation(11.1%)and 2 splicing mutations(22.2%).Large fragment deletions were detected by MLPA in 2 families.The total mutation detection rate of micromutations and large fragment deletions was 78.6%(11/14).CONCLUSION:The detection rate of APC gene germline mutation can be improved by direct sequencing combined with MLPA large fragment deletion detection.

Attenuated adenomatous polyposis of the large bowel: Present and future

Attenuated adenomatous polyposis(AAP) is a poorly understood syndrome, that can be defined as the presence of 10-99 synchronous adenomas in the large bowel, and it is considered a phenotypic variant of familial adenomatous polyposis(FAP). This definition has the advantage of simplicity, but it may include sporadic multiple adenomas of the large bowel at an extreme, or FAP cases on the other side. AAP shows a milder phenotype than FAP, with an older age of onset of adenomas and cancer, and less frequent extracolonic manifestations. AAP may be diagnosed as a single case in a family or, less frequently, it may be present in other family members, and it shows distinct pattern of inheritance. In less than 50% of cases, it may be caused by adenomatous polyposis coli(APC) or MUTYH mutations, referred to as APC-associated polyposis, inherited as an autosomal dominant trait, or MUTYH-associated polyposis, which shows an autosomal recessive mechanism of inheritance, respectively. Surveillance should rely on colonoscopy at regular intervals, with removal of adenomas and careful histological examination. When removal of polyps is not possible or advanced lesions are observed, the surgical approach is mandatory, being subtotal colectomy with ileo-rectal anastomosis the treatment of choice. Studies on this syndrome are lacking, and controversies are still present on many issues, thus, other clinical and genetic studies are requested.

Rare combination of familial adenomatous polyposis and gallbladder polyps

Familial adenomatous polyposis is associated with a high incidence of malignancies in the upper gastrointestinal tract (particularly ampullary adenocarcinomas). However, few reports have described a correlation between familial adenomatous polyposis and gallbladder neoplasms. We present a case of a 60-year-old woman with familial adenomatous polyposis who presented with an elevated mass in the neck of the gallbladder (measuring 16 mm × 8 mm in diameter) and multiple small cholecystic polyps. She had undergone a total colectomy for ascending colon cancer associated with familial adenomatous polyposis 22 years previously. The patient underwent laparoscopic cholecystectomy under a preoperative diagnosis of multifocal gallbladder polyps. Pathologic examination of the resected gallbladder revealed more than 70 adenomatous lesions, a feature consistent with adenoma of the gallbladder. This case suggests a requirement for long-term surveillance of the biliary system in addition to the gastrointestinal tract in patients with familial adenomatous polyposis.

Cumulative incidence and risk factors for pouch adenomas associated with familial adenomatous polyposis following restorative proctocolectomy

BACKGROUND The emergence of restorative total proctocolectomy has significantly reduced the lifetime colorectal cancer risk associated with familial adenomatous polyposis(FAP).However,adenomas may develop in the ileal pouch over time and may even progress to carcinoma.We evaluated the cumulative incidence,time to development,and risk factors associated with ileal pouch adenoma.AIM To evaluate the cumulative incidence,time to development,and risk factors associated with pouch adenoma.METHODS In this retrospective,observational study conducted at a tertiary center,95 patients with FAP who underwent restorative proctocolectomy at our center between 1989 and 2018 were consecutively included.The mean follow-up period was 88 mo.RESULTS Pouch adenomas were found in 24(25.3%)patients,with a median time of 52 mo to their first formation.Tubular adenomas were detected in most patients(95.9%).There were no high-grade dysplasia or malignancies.Of the 24 patients with pouch adenomas,13 had all detected adenomas removed.Among the 13 patients who underwent complete adenoma removal,four(38.5%)developed recurrence.Among 11(45.8%)patients with numerous polyps within the pouch,seven(63.6%)exhibited progression of pouch adenoma.The cumulative risks of pouch adenoma development at 5,10,and 15 years after pouch surgery were 15.2%,29.6%,and 44.1%,respectively.Severe colorectal polyposis(with more than 1000 polyps)was a significant risk factor for pouch adenoma development(hazard ratio,2.49;95% confidence interval:1.04-5.96;P=0.041).CONCLUSION Pouch adenomas occur at a fairly high rate in association with FAP after restorative proctocolectomy,and a high colorectal polyp count is associated with pouch adenoma development.

Three Novel Mutations of APC Gene Found in a Chinese Family with Familial Adenomatous Polyposis

Objective:To identify the causative adenomatous polyposis coli(APC)gene defects associated with a pedigree of familial adenomatous polyposis(FAP).Methods:FAP was diagnosed based on clinical manifestations,family history,as well as endoscopic and pathological examinations.The blood samples of the FAP pedigree members,colonic polyp patients,and normal individuals were collected.Genomic DNA was then extracted from those samples.APC mutation analysis was conducted via direct polymerase chain reaction(PCR)sequencing.Results:Three synonymous mutations and a missense mutation were found:c.5034G>A(p.Glyl678Gly),c.5465T>A(p.Vall 822Asp),c.5880G>A(p.Prol960Pro),and c.5274T>G(p.Serl758Ser)・Among them,the homozygous mutation on APC gene c.5034G>A has been reported,while the other three mutations have not been reported in the Chinese Han population.Individuals with c.5465T>A(p.Vall822ASP)missense mutation eventually suffer from colon cancer and have poor prognosis.We found no mutation in patients with simple intestinal polyp and in normal individuals.In addition,there were homozygous and heterozygous mutations in different patients from the same family.Conclusion:Three new mutations of APC gene were firstly reported in Han population.The missense mutation of c.5465T>A(p.Vall 822Asp)may be the cause of carcinogenesis in this FAP pedigree with poor prognosis.

Clinicopathological features of familial adenomatous polyposis in Korean patients

AIM: To identify prognostic factors and to correlate APC mutations with clinical features, including extracolic manifestations. METHODS: One hundred thirty-five patients who underwent surgical procedures for familial adenomatous polyposis(FAP) were included. FAP was diagnosed when the number of adenomatous polyps was > 100. Data related to patient, extracoloic manifestations, cancer characteristics, operative procedure, follow up and surveillance were collected. APC mutation testing was performed in the 30 most recent patients. DNA was extracted from peripheral blood and polymerase chain reaction products using 31 primer pairs on APC gene were sequenced. A retrospective study was performed to investigate a causal relationship between prognosis and feature of patient.RESULTS: The mean age of the 51 patients with colorectal cancer(CRC) was older than that of those without CRC(30.5 vs 36.9, P = 0.002). Older individuals were more likely to have colon cancer at the time of FAP diagnosis [odds ratio, 4.75(95%CI: 1.71-13.89) and 5.91(1.76-22.12) for 40-49 years and age > 50 vs age < 30). The number of confirmed deaths was 13 and the median age at death was 40 years(range, 27 to 85 years). Ten of the deaths(76.9%) were from CRC. Another cause of two cases of death were desmoid tumors(15.4%). Development of cancer on remnant rectal or ileal mucosa after surgery was not observed. The APC mutation testing revealed 23 pathogenic mutations and one likely pathogenic mutation, among which were four novel mutations. The correlation between mutational status and clinical manifestations was investigated. Mutations that could prodict poor prognosis were at codon 1309 which located on mutation cluster region, codon 1465 and codon 1507.CONCLUSION: Identification of APC mutations should aid in the diagnosis and counseling of family members in terms of early diagnosis and management of FAP.

Current status of the genetic susceptibility in attenuated adenomatous polyposis

Adenomatous polyposis(AP)is classified according to cumulative adenoma number in classical AP(CAP)and attenuated AP(AAP).Genetic susceptibility is the major risk factor in CAP due to mutations in the known high predisposition genes APC and MUTYH.However,the contribution of genetic susceptibility to AAP is lower and less understood.New predisposition genes have been recently proposed,and some of them have been validated,but their scarcity hinders accurate risk estimations and prevalence calculations.AAP is a heterogeneous condition in terms of severity,clinical features and heritability.Therefore,clinicians do not have strong discriminating criteria for the recommendation of the genetic study of known predisposition genes,and the detection rate is low.Elucidation and knowledge of new AAP high predisposition genes are of great importance to offer accurate genetic counseling to the patient and family members.This review aims to update the genetic knowledge of AAP,and to expound the difficulties involved in the genetic analysis of a highly heterogeneous condition such as AAP.

Proton pump inhibitors and an emerging epidemic of gastric fundic gland polyposis

Fundic gland polyps are now commonly recognized during endoscopy. These polyps are benign, often multiple and usually detected in the gastric body and fundus. In the past, these polyps were sometimes associated with familial adenomatous polyposis. In recent years, it has become evident that increasing numbers of these polyps are being detected during endoscopic studies, particularly in patients treated with proton pump inhibitors for prolonged periods. In some, dysplastic changes in these polyps have also been reported. Recent studies have suggested that there may be no increase in risk of colon cancer with long-term proton pump inhibitor therapy. While temporarily reassuring, ongoing vigilance, particularly in those genetically predisposed to colon cancer, is still warranted.

家族性腺瘤性息肉病96例诊治分析

目的：总结家族性腺瘤性息肉病（familial adenomatous polyposis，FAP）的临床表现特征，探讨FAP的诊治经验。方法：回顾1985～2003年96例FAP患者临床资料，分析结肠镜表现特征；回顾2001-2003年22例FAP患者上消化道内镜及腹部影像学检查资料，分析其大肠外病变特征。结果：96例FAP患者中多数患者大肠内息肉呈密生型生长（52／96，54．2％），左半结肠及直肠息肉分布密度呈中至重度，直肠腺瘤癌变率高（23／41，56．1％）。22例FAP患者中伴胃窦部增生性息肉19例，占86．3％；十二指肠各段有息肉样病灶18例，占81．8％（其中腺瘤性息肉12例，无1例癌变）。22例中有3例分别在大肠切除术后5年内发生腹壁、腹盆腔和小肠系膜硬纤维瘤，仅1例手术完整切除治愈。结论：大肠内密集分布腺瘤性息肉是FAP特征性表现，直肠腺瘤性息肉癌变率高，结肠镜是安全、有效的早期诊断方法；上消化道息肉是FAP常见大肠外病变，国人十二指肠腺瘤癌变罕见；硬纤维瘤严重影响FAP患者大肠切除术后的生存质量。

应用组织芯片检测食管鳞状细胞癌中APC、β-catenin、E-cadherin与cyclin D1的表达及其意义

背景与目的:食管鳞状细胞癌(esophageal squamous cell carcinoma,ESCC)的发生是个多因素多阶段的演进过程。Wnt信号转导通路在肿瘤发生发展中起重要作用。本研究探讨4种Wnt通路上的蛋白在食管鳞癌发生中的作用及在早期诊断中的意义。方法:制作由199例食管鳞癌组织与其癌旁164例正常粘膜、34例基底细胞增生和30例不典型增生上皮组成的组织芯片,应用免疫组化方法检测APC、β-catenin、E-cadherin、cyclin D1的表达情况。结果:APC和E-cadherin在ESCC阳性率分别是69.6%、19.6%,均低于各自正常组(98.0%、96.3%,均为P<0.01),β-catenin和cyclinD1在ESCC的异常表达率分别是65.5%和70.9%,均高于各自正常组(1.2%,0.8%,均为P<0.01)。按正常粘膜→基底细胞增生→不典型增生→ESCC的顺序,APC低表达发生在ESCC,β-catenin和E-cadherin表达异常始于不典型增生,cyclin D1过表达始于基底细胞增生。随着ESCC分化程度由高到低的改变,APC、E-cadherin和cyclin D1阳性率逐渐减少,β-catenin逐渐增加。β-catenin的表达与APC无相关(r=-0.10,P>0.05),与E-cadherin呈负相关(r=-0.31,P<0.01),与cyclin D1呈正相关(r=0.49,P<0.01)。结论:APC、E-cadherin、β-catenin和cyclin D1可能在ESCC发生过程中起重要作用。β-catenin、E-cadherin和cyclin D1的表达检测有助于ESCC的早期诊断。

抑癌基因APC启动子甲基化检测及其在肺癌诊断中的应用

目的 建立抑癌基因APC启动子部位甲基化的检测方法 ,并对肺癌临床样品进行初步检测研究。方法 :对肺癌组织提取的DNA及转甲基后的脐带血DNA进行化学修饰 ,以甲基化特异性引物进行基因扩增 (methylationspecificPCR ,MSP)和甲基化序列分析 (methylationsequencing ,MS)。结果 :经转甲基的人脐带血DNA样品MSP检测为阳性 ,其序列与预期相符 ,未经转甲基样品为阴性。 17例肺癌患者的肿瘤及其正常肺组织APC甲基化检测阳性率分别为 4 7% (8/ 17)和 18% (3/ 17) ,1例肺部良性肿瘤及其正常肺组织的检测结果均为阴性 ;对MSP检测为阴性的 9例肺癌患者肿瘤及其正常肺组织进行MS检测分析 ,有 4例APC启动子部位存在CpG甲基化。结论 :利用MSP和MS两种甲基化检测分析手段 ,对 17例临床确诊肺癌组织的检测总阳性率可达 71% (12 / 17)。MSP操作简便 ,价格低廉 ,可适合于大规模肿瘤患者样本的筛查 ;而对于MSP检测为阴性的临床样品 ,可以利用MS进行进一步的确认 ,为临床肺癌诊断提供更准确的信息。

APC不同功能区域对结肠癌细胞株HT-29中β-连环蛋白表达的影响

目的:探讨含有APC蛋白不同功能区域的pEGFP-N3-APC重组质粒对结肠癌细胞株HT-29中β-连环蛋白表达的影响。方法:脂质体介导重组质粒pEGFP-N3-APC1～5转染HT-29,采用绿色荧光及RT-PCR验证重组质粒在细胞中的表达。以Western免疫印迹检测转染后HT-29细胞中β-连环蛋白的表达,以SPSS13.0软件分析电泳条带的灰度值。结果:重组质粒转染HT-29细胞后,绿色荧光及RT-PCR结果显示5个APC蛋白不同功能区域多肽可在细胞中表达。Western免疫印迹结果显示,重组质粒pEGFP-N3-APC1,pEGFP-N3-APC2和pEGFP-N3-APC3对β-连环蛋白表达无影响,而pEGFP-N3-APC4和pEGFP-N3-APC5均可降低结肠癌细胞株HT-29中β-连环蛋白的表达水平,其中以pEGFP-N3-APC5的抑制程度最强。结论:含有APC蛋白中15氨基重复序列+SAMP重复序列的APC5基因片段既可有效降低β-连环蛋白的表达,同时又是相对长度较短的可用于基因治疗的最优片段。

大肠癌APC、β-catenin、E-cadherin和c-myc的表达及意义

目的探讨腺瘤性息肉蛋白(APC)、β-catenin、E-cadherin和c-myc在大肠癌发生、发展中的作用。方法采用免疫组化法检测正常大肠黏膜、大肠腺瘤、大肠腺瘤恶变及大肠癌组织中上述4种蛋白的表达情况。结果大肠癌和大肠腺瘤恶变APC阳性率显著低于大肠腺瘤和正常大肠黏膜(P<0.01)。大肠癌、大肠腺瘤恶变和大肠腺瘤β-catenin胞质/胞核异位表达率、c-myc阳性率显著高于正常大肠黏膜(P<0.01),大肠癌的β-catenin异位表达率显著高于大肠腺瘤(P<0.01)。大肠癌中β-catenin、E-cadherin膜表达缺失率显著高于大肠腺瘤和正常大肠黏膜(P<0.01)。大肠癌中β-catenin异位表达与c-myc阳性表达、E-cadherin阳性表达呈正相关,与APC阳性表达呈负相关。结论APC失表达和(或)β-catenin异位表达、c-myc过表达与大肠癌的发生相关,β-catenin、E-cadherin膜表达缺失与大肠癌的侵袭、转移有关。

散发性结直肠癌组织APC突变的研究

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糖原合酶激酶3β和腺瘤性结肠息肉病蛋白在气道上皮细胞机械损伤修复过程的时空分布

为了探讨糖原合酶激酶3β(glycogen synthase kinase 3β,GSK3β)和腺瘤性结肠息肉病(adenomatous polyposis coli, APC)蛋白在气道上皮细胞(airway epithelial cells,AECs)损伤和修复中的作用,我们采用机械划线损伤的方法建立体外气道上皮损伤修复模型,采用Western blot、免疫荧光双标共聚焦成像和免疫沉淀的方法观察损伤修复过程中APC蛋白和GSK3β在AECs中表达及分布的动态变化。结果显示:(1)用Western blot方法观察到划线损伤0．5 h后即有GSK3β磷酸化增强(P< 0．05),6 h达到高峰(P<0．05),持续到12 h(P<0．05),24 h开始下降,而GSK3β总量大致保持一致。(2)在免疫荧光双标共聚焦成像实验中,划线损伤0 h组APC蛋白主要表达于胞浆,而划线损伤6 h后APC蛋白主要聚集于损伤前沿区的迁移活跃细胞。(3)免疫共沉淀的实验结果显示,划线损伤0 h时GSK3B和APC蛋白能共同沉淀,但在划线损伤6 h之后,两者发生了分离。以上结果表明:划线损伤后AECs立即启动修复过程,此时GSK3B的活性被抑制,促使APC蛋白游离出来;游离出来的APC蛋白则与微管正极结合,增加了微管的稳定性,从而调节细胞骨架运动,促进气道上皮的损伤修复。

Wnt信号通路在肿瘤调控方面的研究进展

Wnt信号通路是一条进化上十分保守的信号通路,控制着细胞的生长、分化、凋亡和自我更新。在肿瘤的发生发展中,该通路常常异常激活,并能够和其他信号通路协同或拮抗调节肿瘤的增殖、迁移和侵袭。该文主要对Wnt信号通路的研究进展及其在各类肿瘤生长调控中的作用进行简要综述。

子宫内膜样腺癌APC基因表达和甲基化的初步研究

背景与目的:子宫内膜癌是女性生殖系统常见的恶性肿瘤之一。在我国,近年来其发病率亦显著上升。APC基因是一种抑癌基因,在很多组织中都有表达,其表达与卵巢癌有一定的关系。本实验探讨APC基因的甲基化和表达与子宫内膜样腺癌的发生发展的关系。方法:运用甲基化特异性PCR、RT-PCR、免疫组化方法检测了30例正常的增生期子宫内膜组织、30例不典型增生的子宫内膜组织、60例子宫内膜样腺癌组织中APC基因的甲基化情况以及mRNA和蛋白的表达情况。结果:子宫内膜样腺癌组织中APC基因的甲基化率(65.0%)、mRNA表达率(33.3%)及APC蛋白表达率(30.0%)与不典型增生子宫内膜组织(33.3%、63.3%、50.0%)及正常子宫内膜(23.3%、73.3%、66.7%)相比,差异均具有显著性(P<0.05);而不典型增生子宫内膜组织和正常子宫内膜组织中,APC的甲基化率、mRNA表达率及APC蛋白表达率差异无统计学意义(P>0.05)。在这3种组织中,APC基因的甲基化和mRNA的失表达呈正相关关系。结论:APC的甲基化和表达与子宫内膜样腺癌的发生发展相关。