APC mutations are common in adenomas but infrequent in adenocarcinomas of the non-ampullary duodenum.

BACKGROUND: Recent studies highlighted the clinicopathological heterogeneity of non-ampullary duodenal adenomas and adenocarcinomas, but the detailed process of the malignant transformation remains unclear. METHODS: We analyzed 144 adenomas and 54 adenocarcinomas of the non-ampullary duodenum for immunohistochemical phenotypes, genetic alterations, and mismatch repair (MMR) status to probe their histogenetic relationship. RESULTS: The median ages of patients with adenoma and adenocarcinoma were the same (66 years). Adenomas were histologically classified as intestinal-type adenoma (n = 124), pyloric gland adenoma (PGA, n = 10), gastric-type adenoma, not otherwise specified (n = 9), and foveolar-type adenoma (n = 1). Protein-truncating APC mutations were highly frequent in adenomas (85%), with the highest prevalence in intestinal-type adenomas (89%), but rare in adenocarcinomas (9%; P = 2.1 × 10-23). Close associations between phenotypic marker expression and genetic alterations were observed in adenomas, but not in adenocarcinomas, excluding the common association between GNAS mutations and MUC5AC expression. MMR deficiency was more frequent in adenocarcinomas (20%) than in adenomas (1%; P = 2.6 × 10-6). One MMR-deficient adenoma and three MMR-deficient adenocarcinomas occurred in patients with Lynch syndrome. Additionally, three other patients with an MMR-deficient adenocarcinoma fulfilled the revised Bethesda criteria. CONCLUSION: The discrepant APC mutation frequency between adenomas and adenocarcinomas suggests that APC-mutated adenomas, which constitute the large majority of non-ampullary duodenal adenomas, are less prone to malignant transformation. Non-ampullary duodenal adenocarcinomas frequently exhibit MMR deficiency and should be subject to MMR testing to determine appropriate clinical management, including the identification of patients with Lynch syndrome.

Morphological and functional abnormalities of hippocampus in APC1638T/1638T mice.

In the present study, we examined morphology and function of hippocampus in the APC1638T/1638T mouse. Expression levels of the APC mRNA and protein were both identical in the hippocampus of the APC+/+ and APC1638T/1638T mice. The dentate gyrus of the APC1638T/1638T hippocampus was thicker, and has more densely-populated granule cells in the APC1638T/1638T mouse hippocampus. Immunoelectron microscopy revealed co-localization of APC with alpha-amino-3- hydroxy-5-methyl- isoxazole-4-propionate receptor (AMPA-R) and with PSD-95 at post-synapse in the APC+/+ hippocampus, while APC1638T was co-localized with neither AMPA-R nor PSD-95 in the APC1638T/1638T hippocampus. By immunoprecipitation assay, full-length APC expressed in the APC +/+ mouse was co-immunoprecipitated with AMPA-R and PSD-95. In contrast, APC1638T expressed in the APC1638T/1638T mouse was not co-immunoprecipitated with AMPA-R and PSD-95. In the hippocampal CA1 region of the APC1638T/1638T mouse, c-Fos expression after electric foot shock was decreased compared with the APC+/+ mouse. The present study showed some abnormalities on morphology of the hippocampus caused by a truncated APC (APC1638T). Also, our findings suggest that failure in APC binding to AMPA-R and PSD-95 may bring about less activities of hippocampal neurons in the APC1638T/1638T mouse.

Effects of supplemental calcium and vitamin D on the APC/ß-catenin pathway in the normal colorectal mucosa of colorectal adenoma patients.

APC/ß-catenin pathway malfunction is a common and early event in colorectal carcinogenesis. To assess calcium and vitamin D effects on the APC/ß-catenin pathway in the normal-appearing colorectal mucosa of sporadic colorectal adenoma patients, nested within a larger randomized, double-blind, placebo-controlled, partial 2 × 2 factorial chemoprevention clinical trial of supplemental calcium (1200 mg daily) and vitamin D (1000 IU daily), alone and in combination versus placebo, we assessed APC, ß-catenin, and E-cadherin expression in colon crypts in normal-appearing rectal mucosa biopsies from 104 participants at baseline and 1-yr follow up using standardized, automated immunohistochemistry and quantitative image analysis. For vitamin D versus no vitamin D, the ratio of APC expression to ß-catenin expression in the upper 40% (differentiation zone) of crypts (APC/ß-catenin score) increased by 28% (P = 0.02), for calcium versus no calcium it increased by 1% (P = 0.88), and for vitamin D + calcium versus calcium by 35% (P = 0.01). Total E-cadherin expression increased by 7% (P = 0.35) for vitamin D versus no vitamin D, 8% (P = 0.31) for calcium versus no calcium, and 12% (P = 0.21) for vitamin D + calcium versus calcium. These results support (i) that vitamin D, alone or in combination with calcium, may modify APC, ß-catenin, and E-cadherin expression in humans in directions hypothesized to reduce risk for colorectal neoplasms; (ii) vitamin D as a potential chemopreventive agent against colorectal neoplasms; and (iii) the potential of APC, ß-catenin, and E-cadherin expression as treatable, pre-neoplastic risk biomarkers for colorectal neoplasms. © 2016 Wiley Periodicals, Inc.

Molecular mechanism of adenomatous polyposis coli-induced blockade of base excision repair pathway in colorectal carcinogenesis.

Colorectal cancer (CRC) is the third leading cause of death in both men and women in North America. Despite chemotherapeutic efforts, CRC is associated with a high degree of morbidity and mortality. Thus, to develop effective treatment strategies for CRC, one needs knowledge of the pathogenesis of cancer development and cancer resistance. It is suggested that colonic tumors or cell lines harbor truncated adenomatous polyposis coli (APC) without DNA repair inhibitory (DRI)-domain. It is also thought that the product of the APC gene can modulate base excision repair (BER) pathway through an interaction with DNA polymerase ß (Pol-ß) and flap endonuclease 1 (Fen-1) to mediate CRC cell apoptosis. The proposed therapy with temozolomide (TMZ) exploits this particular pathway; however, a high percentage of colorectal tumors continue to develop resistance to chemotherapy due to mismatch repair (MMR)-deficiency. In the present communication, we have comprehensively reviewed a critical issue that has not been addressed previously: a novel mechanism by which APC-induced blockage of single nucleotide (SN)- and long-patch (LP)-BER play role in DNA-alkylation damage-induced colorectal carcinogenesis.

Prevalence and molecular characterisation of the sessile serrated adenoma in a subset of the Chinese population.

AIMS: The incidence and mortality rates from right-sided colorectal cancers (CRCs) have not decreased in recent years. It is very likely that a significant proportion of these cancers evolve from undetected sessile serrated adenomas (SSAs). The prevalence and molecular features of the SSAs in the Chinese population have seldom been investigated. METHODS: We retrospectively reviewed the colonoscopy database and pathology archives in our medical centre. Adenomatous polyposis coli (APC) and ß-catenin expressions were examined in 28 right hyperplastic polyps (RHPs) and 21 SSAs by immunohistochemical staining. The mutations of BRAF, KRAS, APC and ß-CATENIN were analysed by direct sequencing. The methylation status of APC promoter in these polyps was analysed by methylation-specific PCR and bisulfite sequencing. Samples of left hyperplastic polyps, traditional adenomas and CRC were used as controls. RESULTS: SSAs accounted for 4.9% of serrated polyps and 1.0% of all colorectal polyps. BRAF((V600E)) mutations were found in 14.3% of SSAs and 7.1% of RHPs. Nuclear accumulation of ß-catenin was seen in 28.6% of SSAs and 17.9% of RHPs. APC mutations were detected in 57.1% of SSAs and 67.9% of RHPs. APC methylation was detected in 14.3% of RHPs and 23.8% of SSAs. CONCLUSIONS: The prevalence of SSAs in a subset of the Chinese population is much lower than that in the Western population. BRAF((V600E)) mutation is not a frequent event in right colon serrated polyps in a subset of the Chinese population. APC mutation is possibly the main cause for the Wnt signalling activation in right colon serrated polyps.

Utilization of liquid chromatography mass spectrometry analyses to identify LKB1-APC interaction in modulating Wnt/ß-catenin pathway of lung cancer cells.

UNLABELLED: STK11/LKB1, a serine/threonine protein kinase and tumor suppressor, is a key upstream kinase of adenine monophosphate-activated protein kinase, which is a kinase involved in controlling cell polarity and maintaining cellular energy homeostasis. LKB1 is mutated in a significant number of Peutz-Jeghers syndrome (PJS) cases and sporadic cancers, and is most frequently mutated in lung adenocarcinomas; however, little is known about how LKB1 is involved in lung cancer progression. In this study, immunoprecipitation-HPLC tandem mass spectrometry (IP-LC-MS/MS) was performed to identify novel proteins interacting with LKB1 in lung cancer. Interestingly, many LKB1-interacting proteins acquired from the LC-MS/MS approach were mapped, using MetaCore pathway analysis, to the cystic fibrosis transmembrane conductance regulator activation pathway. Moreover, it was determined that LKB1 directly interacts with APC, and this LKB1-APC interaction was further confirmed by reverse immunoprecipitation assays, but GSK3ß was dispensable for the association of LKB1 and APC. Importantly, LKB1 binds to APC to suppress the Wnt/ß-catenin signaling pathway, which is known to be involved in cell proliferation and migration. Subsequent analysis of the downstream targets of the Wnt/TCF pathway led to the identification of several Wnt-regulated genes, such as CD44, COX-2, survivin, and c-Myc, whose expression levels are downregulated by LKB1. In summary, these results demonstrate that LKB1 regulates the Wnt pathway through a direct interaction with APC to suppress the tumorigenic/metastatic potential of lung tumors. IMPLICATIONS: LKB1 status influences the molecular circuitry (Wnt/ß-catenin pathway), cellular biology, and may serve as a potential therapeutic node in genetically defined subsets of lung cancer.

Barrett's esophagus in the patients with familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is caused by germ line mutations in the APC gene. Barrett's esophagus (BE) and Barrett's adenocarcinoma are intestinal type lesions of the esophagus characterized by an early loss of heterozygosity at the APC locus. We hypothesized that patients with FAP are at risk for the early development of BE due to the inherited mutations in the APC gene (haploinsufficiency). Upper gastrointestinal (UGI) tract biopsies from 36 patients with FAP were reviewed to determine the incidence and characteristics of BE in these patients. Twenty-four patients were confirmed carriers of a deleterious germline APC mutation. The other 12 patients were from FAP families with known APC gene mutations and had clinical manifestations of FAP. The control group consisted of patients who did not have a personal or family history of FAP undergoing UGI endoscopic examination in our institution over a 30 month period of time. The difference in expression of Wnt pathway proteins (APC, ß-catenin, E-cadherin and cyclin D1) in BE between BE(+)/FAP(+), BE(-)/FAP(+) and age-matched BE(+)/FAP(-) groups was studied using immunohistochemistry. BE was found in 6 of 36 (6/36 or 16%) patients with FAP and in 266 of 1662 patients (16%) in the control group of symptomatic patients. The average age at the first diagnosis of BE in FAP patients was 37.8 versus 57.5 years in the control group (sporadic BE). When compared to age matched BE(+)/FAP- group (7/334), patients with FAP had a significantly (p = 0.005843, odds ratio 9.2; Fisher exact test) higher incidence of BE. Both classic FAP and attenuated FAP phenotypes were associated with BE .Two types of germ line mutations in APC gene were identified in BE(+)/FAP(+) patients: Five patients had 2-base deletion in exon 4 (426delAT) and one patient had 4-base deletion in exon 15 (3202del4). No difference in Wnt signaling pathway proteins expression was detected between BE(+)/FAP(+) and the age matched group of patients with sporadic BE (BE(+)/FAP(-)). Patients with FAP appear to have increased risk for the development of BE, which on average develops some 20 years earlier than in patients without FAP. This association needs to be taken in account when caring for the patients with FAP.

Expression of APC, ß-catenin and E-cadherin in Tunisian patients with gastric adenocarcinoma: clinical significance.

Aberrant activation of the Wnt signalling pathway is a key feature of many cancers. ß-Catenin, adenomatous polyposis coli (APC) and E-cadherin are major players in this pathway. The aim of this study is to examine the expression of ß-catenin, APC and E-cadherin in tumour tissues of 80 Tunisian patients with gastric carcinoma and to determine the methylation status of the APC promoter in tumour tissues. Associations between protein expression and clinico-pathological parameters, including prognosis, were performed. Positive expression of ß-catenin, APC and E-cadherin was observed in 77.5, 68.7 and 60% of cases, respectively. Tumours lacking membranous expression of ß-catenin had greater extent of lymph node metastasis, poor differentiation and advanced T-stage. The expression of E-cadherin correlated with poor differentiation (P = 0.05) and ß-catenin expression (P = 0.004). With regards to prognosis, the overall survival time was significantly prolonged for patients showing normal ß-catenin expression (exclusively or predominantly membranous staining) alone or combined with positive APC expression (P log rank = 0.008 and 0.003, respectively). The methylated pattern of APC promoter 1A was detected in 43.8% of cases and correlated with T-stage (P = 0.046) and distant metastasis (P = 0.037). No correlation was found between the methylated profile of APC promoter 1A and the expression of APC protein in tumour tissues. Our findings suggest that deregulation of the Wnt pathway via abnormal expression of ß-catenin and E-cadherin occurred frequently in gastric carcinoma and correlated with worse clinical behaviour.

Relationship among expression of basic-fibroblast growth factor, MTDH/astrocyte elevated gene-1, adenomatous polyposis coli, matrix metalloproteinase 9,and COX-2 markers with prognostic factors in prostate carcinomas.

BACKGROUND: The etiopathogenesis of prostate cancer (PC) is still not clear, but hormonal, genetic, and environmental factors are thought to play a role in the tumor pathogenesis. Astrocyte elevated gene-1(AEG-1) as a novel transmembrane protein is predominantly located in the perinuclear region and endoplasmic reticulum. It has been found that AEG-1 upregulation increases the invasive ability of glioma and prostate cancer. Basic fibroblast growth factor (bFGF), matrix metalloproteinase-9 (MMP-9), cyclooxygenases-2 (COX-2), and adenomatous polyposis coli (APC) are very important in tumor progression as well. MATERIALS AND METHODS: This study included 97 radical prostatectomy specimens. IHC stains for bFGF, MMP-9, COX-2, APC, and AEG-1 were performed on the tissue microarray using standard procedures. For each patient, the age, Gleason score, tumor volume, lymphovascular invasion, lymph node metastasis, surgical margin, and the invasion of vesiculoseminalis areas were assessed. Analyses were performed using the statistical PASW (ver. 18). RESULTS: Statistically significant positive relationships were found MMP-9 and COX-2 (r = 0.242 and P = 0.017), between MMP-9 and APC (r = 0.207 and P = 0.043), and between bFGF and AEG-1 (r = 0.295 and P = 0.004). However, the relationships between age and staining results and tumor volume and staining results were not found to be significant. Although a positive correlation was found between the Gleason score and tumor volume and the Gleason score and age (r = 0.415 and P = 0.0001; r = 0.246 and P = 0.015, respectively), we did not find a statistically significant relationship between other stains and other prognostic parameters (lymphovascular invasion, lymph node metastasis, surgical margin, or vesiculoseminalis invasion). CONCLUSION: The relationships we found between MMP-9 and COX-2, between MMP-9, and APC and between bFGF and AEG-1 as independent prognostic parameters could be helpful in the development of new therapeutic procedures.

CTNNB1, AXIN1 and APC expression analysis of different medulloblastoma variants.

OBJECTIVES: We investigated four components of the Wnt signaling pathway in medulloblastomas. Medulloblastoma is the most common type of malignant pediatric brain tumor, and the Wnt signaling pathway has been shown to be activated in this type of tumor. METHODS: Sixty-one medulloblastoma cases were analyzed for ß-catenin gene (CTNNB1) mutations, ß-catenin protein expression via immunostaining and Wnt signaling pathway-related gene expression. All data were correlated with histological subtypes and patient clinical information. RESULTS: CTNNB1 sequencing analysis revealed that 11 out of 61 medulloblastomas harbored missense mutations in residues 32, 33, 34 and 37, which are located in exon 3. These mutations alter the glycogen synthase kinase-3ß phosphorylation sites, which participate in ß-catenin degradation. No significant differences were observed between mutation status and histological medulloblastoma type, patient age and overall or progression-free survival times. Nuclear ß-catenin accumulation, which was observed in 27.9% of the cases, was not associated with the histological type, CTNNB1 mutation status or tumor cell dissemination. The relative expression levels of genes that code for proteins involved in the Wnt signaling pathway (CTNNB1, APC, AXIN1 and WNT1) were also analyzed, but no significant correlations were found. In addition, large-cell variant medulloblastomas presented lower relative CTNNB1 expression as compared to the other tumor variants. CONCLUSIONS: A small subset of medulloblastomas carry CTNNB1 mutations with consequent nuclear accumulation of ß-catenin. The Wnt signaling pathway plays a role in classic, desmoplastic and extensive nodularity medulloblastoma variants but not in large-cell medulloblastomas.

CTNNB1, AXIN1 and APC expression analysis of different medulloblastoma variants

OBJECTIVES: We investigated four components of the Wnt signaling pathway in medulloblastomas. Medulloblastoma is the most common type of malignant pediatric brain tumor, and the Wnt signaling pathway has been shown to be activated in this type of tumor. METHODS: Sixty-one medulloblastoma cases were analyzed for β-catenin gene (CTNNB1) mutations, β-catenin protein expression via immunostaining and Wnt signaling pathway-related gene expression. All data were correlated with histological subtypes and patient clinical information. RESULTS: CTNNB1 sequencing analysis revealed that 11 out of 61 medulloblastomas harbored missense mutations in residues 32, 33, 34 and 37, which are located in exon 3. These mutations alter the glycogen synthase kinase-3β phosphorylation sites, which participate in β-catenin degradation. No significant differences were observed between mutation status and histological medulloblastoma type, patient age and overall or progression-free survival times. Nuclear β-catenin accumulation, which was observed in 27.9% of the cases, was not associated with the histological type, CTNNB1 mutation status or tumor cell dissemination. The relative expression levels of genes that code for proteins involved in the Wnt signaling pathway (CTNNB1, APC, AXIN1 and WNT1) were also analyzed, but no significant correlations were found. In addition, large-cell variant medulloblastomas presented lower relative CTNNB1 expression as compared to the other tumor variants. CONCLUSIONS: A small subset of medulloblastomas carry CTNNB1 mutations with consequent nuclear accumulation of β-catenin. The Wnt signaling pathway plays a role in classic, desmoplastic and extensive nodularity medulloblastoma variants but not in large-cell medulloblastomas.

Hypermethylation of adenomatous polyposis coli gene promoter is associated with novel Wnt signaling pathway in gastric adenomas.

BACKGROUND AND AIM: Gastric adenomas (GAs) are considered as premalignant lesions of gastric adenocarcinoma. The role of Wnt signaling pathway in GAs is rarely identified. In the present study, we aimed to determine whether Wnt signaling plays a role in the pathogenesis of GAs, and to clarify the mechanism of Wnt signaling in GAs. METHODS: The study investigated the relationship between clinicopathological characteristics, Helicobacter pylori (Hp) infection, adenomatous polyposis coli (APC) promoter methylation, APC and ß-catenin immunohistochemistry expression and mutation status, compared with 38 gastric adenoma and periadenomatous tissues (PTs). RESULTS: The abnormal expression of ß-catenin in PTs, low-grade adenomas (LGAs) and high-grade adenomas (HGAs) was 0%, 9.09% and 81.25%. For APC, immunoreactive score (IRS) was 5.50 ± 0.5 in PTs, 3.59 ± 1.4 in LGAs and 1.8 ± 2.0 in HGAs. The scores in LGAs and HGAs were significantly lower than those in PTs (P = 0.000). IRS reflected significantly reduced expression of APC in HGAs (P = 0.002). The absent expression of APC had a correlation with the expression of ß-catenin (P = 0.000). Four LGAs (18.18%) and nine HGAs (56.25%) had methylation of APC. APC promoter methylation correlated with the grade (P = 0.014) and the expression of ß-catenin and APC (P = 0.000). Genes mutation was detected in only two adenomas (5.3%). The presence of Hp in HGAs (43.8%) was significantly higher than in LGAs (13.6%) (P = 0.038). But there was no statistical correlation to growth pattern, size, APC hypermethylation and gene mutation. CONCLUSION: Hypermethylation of APC promoter, instead of mutations involving APC and ß-catenin, may play a role in the development and progression of GAs contributing to moderate activation of Wnt signaling. Helicobacter pylori may accelerate the progress of gastric adenoma, but the pathogenesis needs further research.

Double recognition of oligonucleotide and protein in the detection of DNA methylation with surface plasmon resonance biosensors.

DNA methylation plays an essential role in maintenance of cellular function. A growing number of human diseases have been found to be associated with aberrant DNA methylation, especially cancer. However, current technologies used in DNA methylation detection are complicated and time consuming. A promotor of the Adenomatous polyposis coli (APC) gene, a well-studied tumor suppressor gene, was used as the detection target DNA sequence. The double recognition mechanism was realized with oligonucleotide probe hybridization and specific protein binding. First, complementary target DNA was captured by the probe immobilized onto a surface plasmon resonance (SPR) sensor chip. Then, the recombinant methyl-CpG binding domain (MBD) protein was passed over the surface to recognize and bind to methylated CpG sites. Binding resulted in an increase in the refractive index, and a detectable optical signal was generated. Five picomoles of methylated APC promotor DNA could be easily detected with this method. The entire detection could be completed within 1h. This work represents the first SPR based biosensor technology, which achieves simple and specific DNA methylation detection and avoids complicated bisulfite treatment and methylation-sensitive restriction digestion. It will improve our ability to detect DNA methylation specifically and rapidly, and promote our understanding of the role of DNA methylation in gene regulation and diseases.

Cell type-specific expression of adenomatous polyposis coli in lung development, injury, and repair.

Adenomatous polyposis coli (Apc) is critical for Wnt signaling and cell migration. The current study examined Apc expression during lung development, injury, and repair. Apc was first detectable in smooth muscle layers in early lung morphogenesis, and was highly expressed in ciliated and neuroendocrine cells in the advanced stages. No Apc immunoreactivity was detected in Clara or basal cells, which function as stem/progenitor cell in adult lung. In ciliated cells, Apc is associated mainly with apical cytoplasmic domain. In response to naphthalene-induced injury, Apc(positive) cells underwent squamous metaplasia, accompanied by changes in Apc subcellular distribution. In conclusion, both spatial and temporal expression of Apc is dynamically regulated during lung development and injury repair. Differential expression of Apc in progenitor vs. nonprogenitor cells suggests a functional role in cell-type specification. Subcellular localization changes of Apc in response to naphthalene injury suggest a role in cell shape and cell migration.

Expression and significance of adenomatous polyposis coli, beta-catenin, E-cadherin and cyclin D1 in esophageal squamous cell carcinoma assessed by tissue microarray.

BACKGROUND AND OBJECTIVE: The genesis of esophageal squamous cell carcinoma(ESCC)is a multifactor and multistage process, in which Wnt signaling transduction pathway plays an important role in tumorigenesis and tumor progression. This study was to investigate the roles of four proteins in the Wnt pathway in tumorigenesis of ESCC, and their significances in the early diagnosis of ESCC. METHODS: The expression of adenomatous polyposis coli (APC), beta-catenin, E-cadherin and cyclinD1 was detected by immunohistochemistry using tissue microarrays consisting of 199 specimens of ESCC, 164 specimens of normal mucosa, 34 specimens of basal cell hyperplasia and 30 specimens of dysplasia adjacent to cancer tissues. RESULTS: The positive rates of APC and E-cadherin in ESCC were lower than those in the normal group (69.6% vs. 98.0%, p < 0.01; 19.6% vs. 96.3%, p < 0.01). The abnormal expression rates of beta-catenin and cyclin D1 in ESCC were higher than those in the normal group (65.5% vs. 1.2%,p < 0.01; 70.9% vs. 0.8%, p < 0.01). In accordance with the following order, normal epithelia --> basal cell hyperplasia --> dysplasia --> ESCC, hypoexpression of APC proteins occurred in ESCC, abnormalities of beta-catenin and E-cadherin started to appear in dysplasia, and overexpression of Cyclin D1 emerged from basal cell hyperplasia. From well to poorly differentiated ESCC, the expression of APC, E-cadherin and cyclin D1 were gradually reduced, while beta-catenin was increased. The expression of beta-catenin was not correlated with APC (r = -0.10, p > 0.05), was negatively correlated with E-cadherin (r = -0.31,p < 0.01) and positively correlated with cyclin D1(r = 0.49, p < 0.01). CONCLUSION: APC, E-cadherin, beta-catenin and cyclin D1 may play important roles in tumorigenesis of ESCC. Therefore, detection of E-cadherin, beta-catenin and cyclin D1 proteins may be helpful for the early diagnosis of ESCC.

[Expression and methylation of adenomatous polyposis coli gene in endometrioid adenocarcinoma].

BACKGROUND & OBJECTIVE: Endometrial carcinoma is a common malignant tumor of female reproductive system, with an increasing incidence in China. Adenomatous polyposis coli (APC) gene, a tumor suppressor gene, is expressed in many tissues, and has a certain relationship with ovarian cancer. This study was to observe the expression and DNA methylation of APC gene in endometrioid adenocarcinoma, and explore its correlations to the occurrence and development of this disease. METHODS: The methylation, mRNA and protein expression of APC gene were detected by methylation-specific polymerase chain reaction (PCR), reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry in 30 specimens of normal proliferative endometrium, 30 specimens of atypical hyperplastic endometrium and 60 specimens of endometrioid adenocarcinoma. RESULTS: The methylation rate of APC gene was significantly higher, the positive rates of APC mRNA and protein were significantly lower in endometrioid adenocarcinoma than in atypical hyperplastic endometrium and normal proliferative endometrium (65.0% vs. 33.3% and 23.3%, 33.3% vs. 63.3% and 73.3%, 30.0% vs. 50.0% and 66.7%,P<0.05). There was no significant difference between atypical hyperplastic endometrium and normal endometrium (P>0.05). APC methylation was positively correlated to APC mRNA expression. CONCLUSION: The expression and DNA methylation of APC gene are certainly related with the occurrence and development of endometrioid adenocarcinoma.

APC nuclear membrane association and microtubule polarity.

BACKGROUND INFORMATION: Directional cell migration is a fundamental feature of embryonic development, the inflammatory response and the metastatic spread of cancer. Migrating cells have a polarized morphology with an asymmetric distribution of signalling molecules and of the actin and microtubule cytoskeletons. The dynamic reorganization of the actin cytoskeleton provides the major driving force for migration in all mammalian cell types, but microtubules also play an important role in many cells, most notably neuronal precursors. RESULTS: We previously showed, using primary fibroblasts and astrocytes in in vitro scratch-induced migration assays, that the accumulation of APC (adenomatous polyposis coli; the APC tumour suppressor protein) at microtubule plus-ends promotes their association with the plasma membrane at the leading edge. This is required for polarization of the microtubule cytoskeleton during directional migration. Here, we have examined the organization of microtubules in the soma of migrating neurons and fibroblasts. CONCLUSIONS: We find that APC, through a direct interaction with the NPC (nuclear pore complex) protein Nup153 (nucleoporin 153), promotes the association of microtubules with the nuclear membrane.

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 Coli (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.

Wnt/beta-catenin signaling pathway is active in pancreatic development of rat embryo.

AIM: To elucidate the role of Wnt/beta-catenin signaling pathway in pancreatic development of rat embryo. METHODS: The mRNAs of beta-catenin, APC, cyclin D1 genes were amplified by means of semiquantitative reverse transcription polymerase chain reaction (RT-PCR) from embryonic pancreas in different periods and normal pancreas of rat, respectively. Protein expression of these genes in embryonic pancreas of E14.5-E18.5 was examined by immunohistochemical method. RESULTS: In embryonic pancreas of E14.5, the transcript amplification of beta-catenin and cyclinD1 genes was detected. In embryonic pancreas of E18.5, the transcription levels of beta-catenin and cyclinD1 genes became much higher than in other periods. But in adult rat pancreas the transcription of cyclinD1 gene could not be observed. Only until E18.5, the transcript amplification of mRNA of APC gene could be detected. Surprisingly, the transcription level of APC gene became much higher in adult rat pancreas than in embryonic pancreas. By means of immunohistochemical staining, identical results were obtained to the above by RP-PCR, except for beta-catenin protein in adult rat pancreas. CONCLUSION: Active Wnt/beta-catenin signaling occurs in rat embryonic pancreas and is probably important for pancreatic development and organ formation.

Adenomatous polyposis coli on microtubule plus ends in cell extensions can promote microtubule net growth with or without EB1.

In interphase cells, the adenomatous polyposis coli (APC) protein accumulates on a small subset of microtubules (MTs) in cell protrusions, suggesting that APC may regulate the dynamics of these MTs. We comicroinjected a nonperturbing fluorescently labeled monoclonal antibody and labeled tubulin to simultaneously visualize dynamics of endogenous APC and MTs in living cells. MTs decorated with APC spent more time growing and had a decreased catastrophe frequency compared with non-APC-decorated MTs. Endogenous APC associated briefly with shortening MTs. To determine the relationship between APC and its binding partner EB1, we monitored EB1-green fluorescent protein and endogenous APC concomitantly in living cells. Only a small fraction of EB1 colocalized with APC at any one time. APC-deficient cells and EB1 small interfering RNA showed that EB1 and APC localized at MT ends independently. Depletion of EB1 did not change the growth-stabilizing effects of APC on MT plus ends. In addition, APC remained bound to MTs stabilized with low nocodazole, whereas EB1 did not. Thus, we demonstrate that the association of endogenous APC with MT ends correlates directly with their increased growth stability, that this can occur independently of its association with EB1, and that APC and EB1 can associate with MT plus ends by distinct mechanisms.